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Master The NCERT for NEET Biology - Vol.2

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Complete Practice of NCERT for
NEET 11& 12
ASTER THE CERT
BIOLOGY-II
Thousands of MCQs Based on
Each & Every Topic of Latest NCERT
Class-XII
SANJAY SHARMA
Co-authored by
Sanubia
Kavita Thareja
ARIHANT PRAKASHAN (Series), MEERUT
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Arihant Prakashan (Series), Meerut
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PREFACE
In the present dynamic scenario of competitions, NCERT Books are gaining importance day
by day. On an average about 30% questions asked in various competitions are from NCERT.
Similarly with the incorporation of Board weightage in competitions the necessity of dual
synchronous preparation i.e., to study NCERT for School Exams and for Competitive Exams,
is increasing day by day. Arihant’s Master the NCERT Series is framed with the philosophy
of such synchronous preparation in mind.
The book consists of 16 chapters, in each of which questions are framed on each & every
line of NCERT text. Some special features of Master the NCERT books which make these
books stand apart from other NCERT based books are
— Each chapter has a NEET Key Notes for quick revision of whole NCERT content.
— Each chapter has topically divided objective questions based on NCERT content to
cover all the topics of NCERT text.
— Separate section in each chapter having special types questions for NEET.
— Complete coverage of NCERT Exemplar objective questions in each chapter.
— Detailed explanations for selected questions.
— Appendix given at the end contains some Important Multicolored Diagrams from the
whole NCERT curriculum.
The variety in types of questions framed will be helpful in analysis of self-performance and
exposures to face tough problems of competitions. Previous Years' Medical Entrance
Questions have also been incorporated at appropriate places so that the students get the
exposure of type of questions asked in various competitions on the same topic.
Huge efforts have been made from our side to keep this book error free, but inspite of that
if any error or whatsoever is skipped in the book then that is purely incidental, apology for
the same, please write to us about that so that it can be corrected in the further edition of
the book. Suggestions for further improvement of the book will also be welcomed &
incorporated in further editions.
Publisher
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CONTENTS
1. REPRODUCTION IN ORGANISMS
1-18
NEET Key Notes
1-4
Mastering NCERT with MCQs
— Lifespan and Asexual Reproduction
— Sexual Reproduction
4-6
7-9
NEET Special Types Questions
NCERT Exemplar Questions
Answers & Explanations
2. SEXUAL REPRODUCTION IN FLOWERING PLANTS
9-12
13-14
15-18
19-44
NEET Key Notes
19-23
—
Mastering NCERT with MCQs
Flower and Development of Gametes
— Pollination
— Double Fertilisation and Development of Endosperm
— Embryo, Seed and Fruit Formation
— Apomixis and Polyembryony
24-28
28-30
30-31
31-32
33
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
33-37
37-38
39-44
3. HUMAN REPRODUCTION
45-71
NEET Key Notes
45-49
Mastering NCERT with MCQs
— Male Reproductive System
— Female Reproductive System
— Gametogenesis
— Menstrual Cycle
— Fertilisation and Implantation
— Pregnancy and Embryonic Development
— Parturition and Lactation
50-51
51-52
53-54
54-56
57-58
58-59
59
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
60-64
64-65
66-71
4. REPRODUCTIVE HEALTH
72-90
NEET Key Notes
Mastering NCERT with MCQs
Reproductive Health-Problems and Strategies
—
72-74
75
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ASTER THE CERT
BIOLOGY-II
—
—
—
Population Stabilisation and Birth Control
Medical Termination of Pregnancy and Sexually Transmitted Infections
Infertility
NEET Special Types Questions
NCERT Exemplar Questions
Answers & Explanations
5. PRINCIPLES OF INHERITANCE AND VARIATION
NEET Key Notes
Class-XII
75-77
77-78
78-79
79-84
84-85
85-90
91-123
91-96
Mastering NCERT with MCQs
— Mendel's Laws of Inheritance
— Inheritance of One Gene
— Inheritance of Two Genes
— Polygenic Inheritance and Pleiotropy
— Sex-Determination
— Mutation
— Genetic Disorders
97
97-100
100-102
102
103
103
104-106
NEET Special Types Questions
NCERT Exemplar Questions
Answers & Explanations
107-112
112-113
114-123
6. MOLECULAR BASIS OF INHERITANCE
124-160
NEET Key Notes
124-130
—
Mastering NCERT with MCQs
The DNA
— The Search for Genetic Material and RNA World
— Replication
— Transcription
— Genetic Code
— Translation
— Regulation of Gene Expression
— Human Genome Project (HGP)
— DNA Fingerprinting
131-133
133-134
134-135
136-137
138-139
139-140
140-141
142
143
NEET Special Types Questions
NCERT Exemplar Questions
Answers & Explanations
144-149
150-151
152-160
7. EVOLUTION
161-188
NEET Key Notes
161-164
Mastering NCERT with MCQs
— Origin of Life and Evolution of Life Forms
165-166
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ASTER THE CERT
BIOLOGY-II
—
—
—
—
—
—
Evidences of Evolution
Adaptive Radiation
Biological Evolution and its Mechanism
Hardy-Weinberg Principle
A Brief Account of Evolution
Origin and Evolution of Man
NEET Special Types Questions
NCERT Exemplar Questions
Answers & Explanations
8. HUMAN HEALTH AND DISEASES
Class-XII
166-168
168-169
169-170
170-172
172-173
173
174-179
180-181
182-188
189-218
NEET Key Notes
189-195
—
Mastering NCERT with MCQs
Human Health and Common Diseases in Humans
— Immunity
— AIDS (Acquired Immuno Deficiency Syndrome)
— Cancer
— Drug and Alcohol Abuse
195-198
198-201
202
203
204-205
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
206-209
210-211
212-218
9. STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION
219-241
NEET Key Notes
219-223
Mastering NCERT with MCQs
— Animal Husbandry, Management of Farms and Farm Animals
— Animal Breeding, Bee-keeping and Fisheries
— Plant Breeding and Single Cell Protein
— Tissue Culture
223-224
224-226
226-229
229-230
NEET Special Types Questions
NCERT Exemplar Questions
Answers & Explanations
230-234
235-236
237-241
10. MICROBES IN HUMAN WELFARE
242-260
NEET Key Notes
242-244
Mastering NCERT with MCQs
— Basic Concepts and Microbes in Household Products
— Microbes in Industrial Products
— Microbes in Sewage Treatment
245-246
246-247
247-248
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ASTER THE CERT
BIOLOGY-II
—
—
Microbes in Production of Biogas
Microbes as Biocontrol Agents and Biofertilisers
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
11. BIOTECHNOLOGY : PRINCIPLES AND PROCESSES
Class-XII
249
249-250
251-254
254-256
256-260
261-283
NEET Key Notes
261-265
Mastering NCERT with MCQs
— Principles of Biotechnology and Restriction Enzymes
— Cloning Vectors and Competent Host
— Processes of Recombinant DNA Technology
— Bioreactors and Downstream Processing
266-269
269-270
271-272
272-273
NEET Special Types Questions
NCERT Exemplar Questions
Answers & Explanations
273-277
277-278
279-283
12. BIOTECHNOLOGY AND ITS APPLICATIONS
284-302
NEET Key Notes
284-286
Mastering NCERT with MCQs
— Biotechnological Applications in Agriculture
— Biotechnological Applications in Medicine
— Transgenic Animals
— Ethical Issues
287-288
289-290
290-291
291
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
292-296
296-297
298-302
13. ORGANISMS AND POPULATION
303-334
NEET Key Notes
303-308
Mastering NCERT with MCQs
— Organism and its Environment
— Population Attributes
— Population Interactions
308-312
313-316
316-319
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
319-324
324-325
326-334
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ASTER THE CERT
BIOLOGY-II
Class-XII
14. ECOSYSTEM
335-364
NEET Key Notes
335-339
Mastering NCERT with MCQs
— Ecosystem-Structure and Function, Productivity and Decomposition
— Energy Flow and Food Chain
— Ecological Pyramids
— Ecological Succession
— Nutrient Cycling and Ecosystem Services
339-341
341-344
345-346
347-348
348-349
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
350-355
355-356
357-364
15. BIODIVERSITY AND CONSERVATION
365-383
NEET Key Notes
365-368
Mastering NCERT with MCQs
— Biodiversity : Levels and Patterns
— Importance and Loss of Biodiversity
— Conservation of Biodiversity
368-370
371
372-373
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
374-377
377-378
379-383
16. ENVIRONMENTAL ISSUES
384-408
NEET Key Notes
384-388
Mastering NCERT with MCQs
— Air Pollution and its Control Measures
— Water Pollution and its Control Measures
— Solid Wastes, Agrochemicals and Radioactive Wastes
— Greenhouse Effect, Global Warming and Ozone Depletion
— Improper Resource Utilisation and Deforestation
389-390
391-392
392-393
393-394
394-395
NEET Special Types Questions
NCERT & NCERT Exemplar Questions
Answers & Explanations
396-401
402-403
404-408
Some Important Diagrams of NCERT (Multicolored Diagrams)
1-8
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CHAPTER 01 > Reproduction in Organisms
1
CHAPTER > 01
Reproduction
in Organisms
NEET
KEY NOTES
Å
The period from birth to the natural death of an organism represents its lifespan. Whatever be the lifespan, death of every
individual organism is a certainty, i.e. no individual is immortal, except single-celled organisms.
Å
Reproduction is a vital biological process by which living organisms produce new individuals of their own species.
It enables continuity of species. Reproduction is of two types asexual and sexual.
Asexual Reproduction
Å
Å
Å
Å
Å
It involves the participation of a single parent to produce an offspring. As a result, the offspring produced are morphologically
and genetically similar to one another and also to their parents and can be referred to as clones.
The unit of reproduction is commonly formed from the somatic cells of the parent. Meiosis does not occur in asexual reproduction.
Asexual reproduction is common among single-celled organisms and in plants and animals with relatively simpler body
organisation.
Cell division itself is a mode of reproduction in protists, e.g. Amoeba and monerans. In bacteria, the parent cell divides into two
to give rise to new individuals.
It may take place by following methods
Asexual Reproduction
Fission
Budding
Binary Parent body divides
into two daughter individuals,
e.g. Amoeba.
Multiple Parent body
divides into many
daughter individuals,
e.g. Plasmodium.
Å
External An outgrowth
(bud) formed on the
parent body constricts
and separates to form a
new organism, e.g. Hydra,
yeast.
Internal Small, gemmules
(internal buds) form new
individuals, e.g. Spongilla
(sponge).
Spore formation
Fragmentation
Spores are
propagules which
germinate to produce
new individuals,
e.g. fungi.
Breaking of
parent body
into fragments and
each fragment
develops into a new
organism,
e.g. Spirogyra.
Regeneration
Formation of the whole
body of an organism from
a small fragment or by
replacement of the lost
body part, e.g. sponge
and Planaria.
During unfavourable conditions, the products of multiple fission become individually surrounded by resistant coats, i.e. cyst
(encystation) and gets released, once favourable condition arises sporulation occurs. It is seen in Amoeba.
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Master The NCERT > BIOLOGY (Vol-II )
2
Å
In Monera, Protista, Fungi and Algae, spores formed can
be of following main types
Pseudopodiospore (with fine pseudopodia) – Amoeba
Zoospores (motile and flagellated) – Chlamydomonas
and Ulothrix
Conidia (non-motile) – Penicillium
n
Sexual Reproduction
Å
In sexual reproduction, there is formation of male and
female gametes either by same individual or by different
individuals of opposite sex. These gametes fuse to form a
new cell called zygote, e.g. occurs in all flowering plants,
humans, etc.
Å
The period of growth from birth up to the reproductive
maturity in an organism is called as juvenile phase. In
plants, this period of growth starting from seed
germination up to initiation of flowering is called
vegetative phase.
Å
The later phase, when the organisms start reproducing
sexually, is called reproductive phase. The end of
reproductive phase is marked by the onset of another
phase called senescent phase which is the last phase in life
cycle after which the organism dies.
Å
A few plants exhibit unusual flowering phenomenon;
some of them such as bamboo species flower only once in
their lifetime, generally after 50-100 years, produce large
number of fruits and die. Another plant, Strobilanthes
kunthiana (Neelakurinji), flowers once in 12 years.
Å
In non-primate mammals like cows, sheep, rats, deers,
dogs, tigers, etc., the cyclical changes during reproduction
are called oestrous cycle whereas in primates (monkeys,
apes and humans) it is called as menstrual cycle.
Å
Many mammals exhibit such cycles only during
favourable seasons in their reproductive phase and are
called seasonal breeders. While those are reproductively
active throughout their reproductive phase are called
continuous breeders.
n
n
n
Sporangiospores (non-motile) – Rhizopus
Å
While in animals and other simple organisms, the term
asexual is used unambiguously, in plants, the term
vegetative reproduction is frequently used.
Å
In plants, units of vegetative propagation such as runner,
rhizome, sucker, tuber, offset, bulb, etc., have capability to
give rise to new offspring. These structures are known as
vegetative propagules.
Types of Vegetative Propagation in Plants
and their Description
Types of Vegetative
Propagation in Plants
Description
1. Natural Vegetative Propagation
Root (Root tubers)
Buds on the roots grow into leafy shoots above
the ground and adventitious roots at the bases,
e.g. sweet potato, guava, etc.
Underground Modified stems possess buds
which grow into new plants. Few types are
Suckers, e.g. mint, Chrysanthemum
Rhizomes, e.g. ginger, turmeric
Bulbs, e.g. onion, garlic
Tubers, e.g. potato
Corms, e.g. Colocasia, Gladiolus.
Creeping Few types include
Runners, e.g. Oxalis, water hyacinth
Offsets, e.g. Pistia.
Aerial modified stems develop new plants when
stem segments fall on the ground, e.g. cacti,
Opuntia.
˜
˜
Stem
˜
˜
˜
˜
˜
Adventitious buds develop on leaves, detach
and form new plants, e.g. Bryophyllum.
Leaves
2. Artificial Vegetative Propagation
Å
Cutting
A small piece of any plant organ is used for
propagation, e.g. leaves (Bryophyllum), roots
(tamarind), stems (sugarcane), etc.
Layering
Roots are artificially induced on stem branches
before these detach from the parent plant, e.g.
jasmine, litchi, etc.
Grafting
Two plant parts, root system (stock) and shoot
system (scion) from two different plants are
joined to form a new plant, e.g. rose, apple, etc.
Micropropagation
Involves culturing of cells, tissues or organs to
form callus which later differentiates to form a
large number of plantlets.
Water hyacinth (scourage of the water bodies or Terror of
Bengal) propagates very quickly by vegetative mode and
drains out dissolved O2 from water bodies.
NEET
Events in Sexual Reproduction
The events of sexual reproduction may be grouped into three
distinct stages namely, the pre-fertilisation, fertilisation and
the post-fertilisation events.
1. Pre-fertilisation Events
Å
These are the events of sexual reproduction which take
place before the fusion of gametes. These include
gametogenesis and gamete transfer.
Gametogenesis
Å
The process of formation of gametes is known as
gametogenesis.
Å
The reproductive units in sexual reproduction are
specialised cells called gametes.
Å
Depending upon the morphological similarity, gametes
can be classified into homogametes or isogametes (in
Cladophora) and heterogametes (in human). The gametes
are generally of two kinds, i.e. male (antherozoid or
sperm) and female (egg or ovum).
KEY NOTES
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3
CHAPTER 01 > Reproduction in Organisms
Å
Sexuality in organisms On the basis of location of
reproductive structure, sexuality in organisms can be
classified as follows
n
n
n
n
Å
Å
Homothallic and monoecious Both male and female
reproductive structures are present on same individual
(bisexual condition), e.g. in several fungi like Mucor and
plants like maize, cucurbits and coconuts.
Å
When the female gamete undergoes development to form
new organisms without fertilisation, the process is called
as parthenogenesis, e.g. rotifers, honeybees, some lizards
and birds (turkey).
Å
Depending upon, where does the syngamy occur,
fertilisation may be of two types
n
Heterothallic and dioecious Male and female
reproductive structures are present on separate
individuals (unisexual condition), e.g. papaya and date
palm. In flowering plants, the unisexual male flower is
staminate, while female is pistillate.
n
Bisexual animals have both male and female
reproductive organs in single individual, e.g.
earthworm, sponge, leech, tapeworm, etc. These are also
called as hermaphrodites.
Unisexual animals have male and female reproductive
organs in different individuals, e.g. cockroach, human,
dog, etc.
Cell division during gamete formation Gametes are
always haploid, but they divide either by mitotic or meiotic
division. The organisms belonging to Monera, Fungi, Algae
and Bryophyta have haploid plant body. These organisms
produce gametes by mitotic division.
In pteridophytes, gymnosperms, angiosperms and most of
the animals including humans, the parental body is
diploid. In these organisms, specialised cells called
meiocytes or gamete mother cells undergo meiosis that
results in the formation of haploid gametes.
It occurs in various ways in different organisms.
n
n
n
After the fusion of male and female gametes, following
processes occur
Zygote
Å
It is the beginning of new life. It is always diploid and
ensures the continuity of race from generation to
generation.
Å
Organism such as fungi, develops a thick wall around it
that is resistant to external damaging factors.
Å
Zygote divides by meiosis to form haploid spores that
grow into haploid individuals in case of organisms which
lead haplontic life cycle, e.g. Volvox, Spirogyra, etc.
Å
In organisms with diplontic life cycle, zygote undergoes
mitotic division and develops into an embryo, e.g. all
flowering plants.
In most organisms, male gamete is motile and female
gamete is non-motile.
Both gametes are motile in few fungi and algae.
In algae, bryophytes and pteridophytes, gamete transfer
takes place through water by producing many male
gametes to ensure fertilisation because during gamete
transfer, large number of male gametes are lost. In
bryophytes and pteridophytes, male gametes are known
as antherozoid.
Embryogenesis
Å
Å
It is the process of development of embryo from zygote.
The events which occur in animals during embryogenesis
are
Mitosis (cell division or cleavage) occurs leading to
the growth of embryo.
n
n
n
In self-fertilising or bisexual plants, e.g. peas, gamete
transfer is easy as the anthers and stigma are closely
located. In cross-fertilising plants, gamete transfer occurs
by pollination. It is the process of transfer of pollen
grains from anther to stigma, e.g. dioecious plants.
2. Fertilisation
Å
It is the complete and permanent fusion of two gametes
from different parents or from the same parent to form a
diploid zygote. This process is also called as syngamy.
Internal fertilisation It is the fusion of gametes that
take place inside the body, e.g. in fungi, higher
animals such as birds, mammals and majority of
plants. The number of ova produced is less, but a large
number of male gametes are formed, as many of them
fail to reach the ova.
3. Post-fertilisation Events
Gamete Transfer
Å
External fertilisation It is the fusion of gametes that
take place outside the body of an organism in external
medium such as water, e.g. in bony fishes, frogs, etc.
A large number of gametes are released in the
surrounding medium by such animals.
n
Å
Cells of embryo undergo differentiation and attain
specific shape, size and function.
Cell differentiation leads to the production of different
tissues, organs and organ systems.
Depending on the development of embryo the animals
can be
(i) Oviparous animals, e.g. reptiles and birds. Here,
embryo develops outside the body of female (eggs).
In these animals, the fertilised eggs are covered by
hard calcareous shell.
NEET
KEY NOTES
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Master The NCERT > BIOLOGY (Vol-II )
4
(ii) Viviparous animals, e.g. majority of mammals
including humans. Here, embryo develops inside
the body of female.
Å
(iii) Ovoviviparous animals, e.g. sharks and rattle
snakes. Here, the female retains the eggs inside
its body after fertilisation and allows the
development of the embryo inside the body
without providing extra nourishment to the
developing embryo as the placenta is absent.
The post-fertilisation events that occur in flowering plants are
n
n
n
n
n
Sepals, petals and stamens wither and shed off.
Pistil remains attached to the plant.
Zygote develops into embryo and the ovules develop into seed.
Ovary develops into the fruit.
Pericarp is produced as the wall of ovary. Seeds disperse by
different agents and germinate into new plants after getting
suitable conditions.
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1
~ Lifespan and Asexual Reproduction
5 Study the given figures and processes representing
1 Lifespan of tortoise is
(a)
(b)
(c)
(d)
the binary fission in Amoeba.
100-150 years
250 years
20 years
1 year
2 Single-celled animals are said to be immortal because
(a)
(b)
(c)
(d)
A
they grow indefinitely in size
they can tolerate any degree of change in temperature
they can reproduce throughout their lifespan
they continue to live as their daughter cells
3 Arrange the organisms shown below in the increasing
order of their lifespans.
Parrot
(a)
(b)
(c)
(d)
Crocodile
Parrot < Crow < Crocodile
Crow < Crocodile < Parrot
Crocodile < Parrot < Crow
Parrot < Crocodile < Crow
4 Reproduction can be considered as
(a)
(b)
(c)
(d)
a biological process
a cycle of birth, growth and death
a process that enables continuity of species
All of the above
Crow
B
D
C
E
A. Daughter cells formation
B. Enlargement of nucleus
C. Parent cell
D. Constricted cell formation
E. Minimisation of pseudopodia
Arrange the figures and processes in the correct
sequence and select the correct answer.
(a)
(b)
(c)
(d)
D→ C→ A→ B→ E
C→ D→ A→ B→ E
C→ E→ B→ D→ A
D→ C→ B→ E→ A
6 Asexual reproduction is a method of reproduction in
which participation of ……… takes place.
(a)
(b)
(c)
(d)
one individual
two individuals (same species)
multi-individuals
two individuals (different species)
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CHAPTER 01 > Reproduction in Organisms
7 Clones are
(a)
(b)
(c)
(d)
5
17 Study the following diagram and the information
morphologically similar individuals
genetically similar individuals
Both (a) and (b)
None of the above
given below.
Conidia
8 ....... is the fastest method to obtain clones.
(a)
(b)
(c)
(d)
Induced mutation
Parasexual hybridisation
Vegetative reproduction
Parthenogenesis
A
B
9 Asexual reproduction is common in
(a)
(b)
(c)
(d)
Mouth
single-celled organisms
plants with relatively simple organisation
animals with relatively simple organisation
All of the above
Bud
10 Cell division is the mode of reproduction in
(a)
(b)
(c)
(d)
monerans
protists
Both (a) and (b)
None of the above
11 Reproduction in Amoeba is carried out through
(a) gemmule formation
(c) budding
(b) binary fission
(d) plasmotomy
12 In Amoeba, under unfavourable conditions, …A…
takes place but under favourable conditions …B…
occurs.
Identify A and B.
(a)
(b)
(c)
(d)
A
Sporulation
Encystation
Binary fission
Multiple fission
B
Encystation
Sporulation
Encystation
Encystation
13 Zoospores are
(a)
(b)
(c)
(d)
D
C
A.
B.
C.
D.
Zoospore of Chlamydomonas.
Conidia of Penicillium.
Buds in Hydra.
Gemmules in sponge.
All the above are
(a)
(b)
(c)
(d)
bodies involved in sexual reproduction
bodies involved in asexual reproduction
bodies of young ones
All the above are correct
18 Refer the given figures which show three different
types of fission.
A.
B.
motile gametes of Chlamydomonas
non-motile gametes of sponges
motile gametes of Hydra
non-motile gametes of Penicillium
C.
14 Asexual reproductive structures found in Penicillium
are
(a) conidia
(c) gemmules
(b) buds
(d) zoospore
15 Gemmule formation is a common mode of
reproduction in
(a) Hydra
(c) Penicillium
(b) sponge
(d) Amoeba
16 Hydra reproduces by
(a) Budding
(c) Gemmule formation
(b) Fragmentation
(d) Both (a) and (b)
A. Longitudinal fission
B. Transverse fission
C. Multiple fission
Select the option which correctly matches them with
the organism in which they occur.
A
B
C
(a)
(b)
(c)
(d)
Euglena
Plasmodium
Euglena
Euglena
Plasmodium
Paramecium
Paramecium
Paramecium
Amoeba
Euglena
Escherichia
Amoeba
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Master The NCERT > BIOLOGY (Vol-II )
6
19 Which one of the following pairs is not correctly
match?
CBSE-AIPMT 2015
Modes of
reproduction
Offset
Rhizome
Binary fission
Conidia
(a)
(b)
(c)
(d)
Examples
(a) 2X
(b) mitotic divisions
(d) parthenogenesis
Y
X–Buds, Y–Nodes
X–Nodes, Y–Adventitious buds
X–Nodes, Y–Adventitious roots
X–Eyes, Y–Nodes
(d) X/2
(b)
(c)
(d)
27 The site of origin of the new plantlets in potato,
Dahlia, ginger and banana is
CBSE-AIPMT 2012
Onion – Bulb
Ginger – Sucker
Chlamydomonas – Conidia
Yeast – Zoospores
(c) X/4
below.
I. The plant was introduced in India because of its
beautiful flowers and shape of leaves.
II. It can propagate vegetatively at a phenomenal rate and
spread all over water body in a short period.
III. It is very difficult to get rid of these plants.
(a)
22 Which one of the following is correctly matched?
(a)
(b)
(c)
(d)
(b) X
26 Identify the plant which contains the features given
21 Refer to the given figures and identify X and Y in these.
(a)
(b)
(c)
(d)
(b) Antherozoid
(d) Bulbil
will be the number of chromosomes in a cell of its
bulbil?
NEET 2018
X
(a) Offset
(c) Rhizome
25 If a leaf cell of Agave have X chromosome, then what
Water hyacinth
Banana
Sargassum
Penicillium
20 Offsets are produced by
(a) parthenocarpy
(c) meiotic divisions
24 Which of the following is not a vegetative propagule?
(a)
(b)
(c)
(d)
floral buds present on stem
internodes of modified stem
nodes of modified stem
adventitious buds present on root
28 Which one of the following options shows two plants
23 Choose the option with correct identification of A, B,
C, D and E given below.
Germinating
Eyes eye buds
Buds
in which new plantlets arise from the same organ?
(a)
(b)
(c)
(d)
Guava and ginger
Potato and sweet potato
Dahlia and mint
Potato and sugarcane
29 Some organisms are capable of asexual or sexual
Adventitious roots
B
A
Leaves
Adventitious
roots
C
D
E
A
B
(a)
Tuber
Rhizome
Eyes
C
Leaf bud
Offset
(b)
Offset
Eyes
Leaf bud
Stolon
Sucker
(c)
Offset
Leaf buds Eyes
Stolon
Sucker
(d)
Tuber
Rhizome
Leaf buds Offset
Bulbil
D
E
reproduction. Under favourable conditions,
reproduction proceeds asexually. When conditions
become more stressful reproduction switches to a
sexual mode. Why?
(a) Sexual reproduction is simple and more rapid allowing
larger numbers of offspring to be produced
(b) Sexual reproduction requires two separate individuals,
who can mutually provide nutrient support during stress
(c) Sexual reproduction produces individuals with new
combinations of recombined chromosomes increasing
diversity
(d) Asexual reproduction requires more energy
30 A scion is grafted to a stock. The quality of fruits
produced will be determined by the genotype of
AIIMS 2018
(a) stock
(c) Both (a) and (b)
(b) scion
(d) Neither (a) nor (b)
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CHAPTER 01 > Reproduction in Organisms
7
TOPIC 2 ~ Sexual Reproduction
31 Which one of the following generates new genetic
combinations leading to variation?
(a)
(b)
(c)
(d)
Vegetative reproduction
Parthenogenesis
Sexual reproduction
Nucellar polyembryony
32 Sexual reproduction involves formation of male and
female gametes by
(a)
(b)
(c)
(d)
same individual
different individual of opposite sex
Both (a) and (b)
All of the above
33 The growth phase of an organism before attaining
sexual maturity is referred to as
(a) juvenile phase
(c) Both (a) and (b)
(b) pre-reproductive phase
(d) None of these
34 Select the correct sequence from the following.
I. Juvenile phase→ Senescent phase→ Reproductive
phase
II. Juvenile phase→ Reproductive phase→ Senescent
phase
III. Reproductive phase→ Juvenile phase→ Senescent
phase
IV. Pre-reproductive phase→ Reproductive phase→
Senescent phase
(a) I and II
(c) III and IV
(b) I and IV
(d) II and IV
35 Which one of the following flowers only once in its
lifetime?
(a) Mango
(c) Bamboo species
39 Select the correct sequence of events.
NEET (Odisha) 2019
NEET 2016, 13
NEET 2018
(a) Gametogenesis → Gamete transfer → Syngamy →
Zygote → Cell division (Cleavage) → Cell
differentiation → Organogenesis
(b) Gametogenesis → Gamete transfer → Syngamy →
Zygote → Cell divison (Cleavage) → Organogenesis→
Cell differentiation
(c) Gametogenesis → Syngamy → Gamete transfer →
Zygote → Cell division (Cleavage) → Cell
differentiation → Organogenesis
(d) Gametogenesis → Gamete transfer → Syngamy →
Zygote → Cell differentiation → Cell division
(Cleavage) → Organogenesis
40 Identify the events (A, B, D and E) of sexual
reproduction given below.
n
Pre-fertilisation event
A E
B CD
Post-fertilisation event
Fertilisation 2n
Choose the correct option.
(a) A–Gamete transfer, B–Gametogeneis, D–Zygote
formation, E–Embryogenesis
(b) A–Gametogeneis, B–Gamete transfer, D–Zygote
formation, E–Embryogenesis
(c) A–Gametogeneis, B–Zygote formation, D–Gamete
transfer, E–Embryogenesis
(d) A–Gametogeneis, B–Gamete transfer,
D–Embryogenesis, E–Zygote formation
41 Identify the type of gametes shown in figure A, B and
C, respectively.
(b) Jackfruit
(d) Papaya
Macrogamete (female)
Flagella
36 Strobilanthes kunthiana is also called
(a) Neelakurinji
(c) Hara kuranji
(b) Peela kuranji
(d) Kala kuranji
Microgamete (male)
A
37 Oestrus cycle is cyclic change in the activities of
ovaries and accessory duct in non-primates during
B
Female gamete (ovum)
(a) reproductive (seasonal) period
(b) maturation period
(c) ageing period
(d) juvenile period
Male gametes (sperms)
38 Organisms reproducing throughout the year are called
…… breeders, e.g. … and those who show recurring
sexual activity are called …… breeders, e.g. … .
(a)
(b)
(c)
(d)
continuous, sparrow, seasonal, hen
seasonal, lizard, continuous, hen
continuous, man, seasonal, tiger
seasonal, hen, continuous, tiger
C
(a)
(b)
(c)
(d)
A–Heterogametes, B–Isogametes, C–Homogametes
A–Homogametes, B–Isogametes, C–Heterogametes
A–Isogametes, B–Heterogametes, C–Heterogametes
A–Heterogametes, B–Heterogametes, C–Isogametes
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Master The NCERT > BIOLOGY (Vol-II )
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42 Name the type of gametes found in algae.
(a) Homogametes
(c) Anisogametes
(b) Heterogametes
(d) All of these
43 What is male gamete called in heterogametic
51 If the parent body is haploid then the gametes are
(a) haploid
(c) triploid
(b) diploid
(d) None of these
52 In diploid organism the gamete producing cells are
called
condition?
(a) Antherozoid
(c) Egg
(b) Sperm
(d) Both (a) and (b)
44 The condition, in which, both male and female
reproductive organs are found on the same plant, is
called
(a) unisexual
(c) monoecious
(a) gamete mother cell
(c) Both (a) and (b)
53 Which of the following is an incorrect combination of
organism with its correct chromosome number in
meiocyte and in gamete?
(b) bisexual
(d) Both (b) and (c)
45 Figure P represents the reproductive organs of a
plant, Chara and figure Q represents the reproductive
organs of an animal, earthworm. Select the option
which correctly identifies male reproductive organs of
the two organisms.
(b) meiocytes
(d) None of these
Name of
organisms
Chromosomes
Chromosomes
number in meiocyte number in gamete
(a)
Butterfly
380
190
(b)
Potato
16
08
(c)
Maize
20
10
(d)
Apple
34
17
54 Identify the sequence of events shown in the diagram
below.
C
A
D
B
P
Q
(a) A and D (b) B and C (c) A and C
(d) B and D
46 The condition in which male and female parts are
present on different organisms, is called
(a) heterothallic
(c) unisexual
(b) dioecious
(d) All of these
47 In flowering plants, the unisexual male flower is
called …A… while the female is called …B… .
Flowering plants may be monoecious, e.g. …C… or
dioecious, e.g. …D… .
Complete the paragraph by filling up the blanks.
(a)
(b)
(c)
(d)
A–staminate, B–pistillate, C–date palm, D–coconut
A–pistillate, B–staminate, C–date palm, D–papaya
A–pistillate, B–staminate, C–Cucurbita, D–coconut
A–staminate, B–pistillate, C–Cucurbita, D–papaya
48 Name the type of gametes formed in staminate and
pistillate flower, respectively.
(a) Stamen, pollen
(c) Stamen, ovum
(b) Antherozoid, egg
(d) Ovum, antherozoid
49 Which of the following is hermaphrodite?
(a) Ant
(b) Aphids (c) Earthworm (d) Cockroach
50 Which among the following is unisexual species?
(a) Tapeworm
(c) Cockroach
(b) Leech
(d) All of these
(a) Fission of gametes → New individual → Zygote
(b) Fusion of gametes → Zygote → New individual
(cell 2n)
(c) Fission of gametes → Zygote → New individual
(cell 2n)
(d) Stages in the gametogenesis
55 Self-fertilisation occurs in the
(a) bisexual flower
(c) Both (a) and (b)
(b) unisexual flower
(d) dioecious flower
56 In which of the following organisms self-fertilisation
is seen?
(a) Peas
(c) Sweet potato
(b) Mustard
(d) All of these
57 Which of the following options is/are correct about
pollination?
(a)
(b)
(c)
(d)
Occurs in almost all flowering plants
Facilitates pollen transfer to stigma
Both (a) and (b)
None of the above
58 Essential and most critical event in sexual
reproduction is
(a)
(b)
(c)
(d)
fertilisation
division in male and female gametes
Both (a) and (b)
None of the above
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CHAPTER 01 > Reproduction in Organisms
66 Embryogenesis involves
59 Fusion of male and female gametes is called
(a) syngamy
(c) Both (a) and (b)
(b) fertilisation
(d) heterogamy
60 In some plants, the female gamete develops into
embryo without fertilisation.
This phenomenon is known as
(a) parthenocarpy
(c) parthenogenesis
NEET 2019
(b) syngamy
(d) autogamy
61 Syngamy may occur in ………… .
(a) external medium
(c) Both (a) and (b)
(b) internal medium
(d) None of these
62 ‘Organisms exhibiting external fertilisation release a
large number of gametes’. Why?
(a) These organisms shows great synchrony between the
sexes
(b) In order to enhance the chances of syngamy
(c) To produce large number of offsprings as they are
vulnerable to predators
(d) All of the above
63 Internal fertilisation is the one in which syngamy
(a)
(b)
(c)
(d)
9
occur outside the body
occur inside the body
is followed by meiosis
None of the above
(a)
(b)
(c)
(d)
formation of embryo from zygote
cell division via meiosis and differentiation
Both (a) and (b)
None of the above
67 Choose the incorrect pair.
(a) Cell division in embryo – Increase the number of cells
(b) Cell differentiation – Form specialised tissues and
organs
(c) Eggs covered by hard calcareous shell – Oviparous
animals
(d) Zygote develops outside the body –Viviparous animals
68 Chances of survival of young ones are more in the case
of............. individuals.
(a) oviparous
(c) ovoviviparous
(b) viviparous
(d) None of these
69 Offsprings of oviparous animals have less chances of
survival as compared to those of viviparous animals
because
(a)
(b)
(c)
(d)
proper embryonic care and protection is absent
embryo does not develop completely
progenies are of smaller size
genetic variations do not occur
70 What does ‘P’ signifies in the diagram given below?
64 Diploid zygote is universal in
(a)
(b)
(c)
(d)
All sexually reproducing organisms
All asexually reproducing organisms
All sexually and asexually reproducing organisms
Only plants and animals
S
S
P
P
65 Life begins in all sexually reproducing organism from a
(a) single-celled zygote
(c) thick-walled zygote
(b) double-celled zygote
(d) All of these
(a) Pistil
(c) Thin pericarp
(b) Thick pericarp
(d) Pollen tube
NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
■ Direction (Q. No. 71-80) In each of the following
questions, a statement of Assertion (A) is given followed
by corresponding statement of Reason (R).
Of the statements, mark the correct answer as
(a) If both A and R are true and R is correct explanation of A
(b) If both A and R are true, but R is not the correct
explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true
71 Assertion (A) A plant can be retained and multiplied
indefinitely without any change or variation through
asexual reproduction.
Reason (R) Asexual reproduction does not involve
meiosis and syngamy.
72 Assertion (A) Offspring formed by asexual
reproduction are called clones.
Reason (R) Clones are morphologically similar.
73 Assertion (A) Reproduction by zoospores occur in
some higher fungi.
Reason (R) Zoospores are motile and flagellated spores.
74 Assertion (A) Zygote is the link between two
generations.
Reason (R) Zygote is the product of two gametes and
the producer of the next generation.
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Master The NCERT > BIOLOGY (Vol-II )
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75 Assertion (A) Vegetative reproduction is a kind of
asexual reproduction in plants.
Reason (R) Vegetative propagules give rise to
offspring.
76 Assertion (A) In perennial plant species, it is difficult
to define vegetative, reproductive and senescent
phases.
Reason (R) Perennial plants have very short lifespan.
77 Assertion (A) Gametes formed in sexual reproduction
are haploid in nature.
Reason (R) Meiocytes undergo meiosis to form
gametes.
78 Assertion (A) Papaya is a dioecious plant.
Reason (R) Dioecious plants are those that have their
reproductive structures on same plants.
79 Assertion (A) In external fertilisation, syngamy
occurs inside the female.
Reason (R) The offspring produced by external
fertilisation are vulnerable to predators.
80 Assertion (A) In flowering plants, zygote is formed
inside the ovule.
Reason (R) The ovule develop into seed after
fertilisation.
II. Statement Based Questions
81 Which one of the following statement regarding
post-fertilisation development in flowering plants is
NEET 2019
incorrect?
(a) Zygote develops into embryo
(b) Central cell develops into endosperm
(c) Ovules develop into embryo sac
(d) Ovary develops into fruit
82 Choose the incorrect statement about gemmules.
(a) They resist dessication
JIPMER 2019
(b) They are internal buds
(c) They are asexual structure which are produce by binary
fission
(d) They can give rise to new organisms
83 Which of the following statements is correct?
(a) All the individuals of a species have exactly the same
lifespan
(b) Smaller organisms always have shorter lifespan and
vice-versa
(c) Lifespan of an organism is the time period from its
birth to its natural death
(d) No organism may have a lifespan of several hundred
years
84 Which one of the following statements is incorrect?
NEET 2016
(a) Offspring produced by the asexual reproduction are
called clone
(b) Microscopic motile asexual reproductive structures are
called zoospores
(c) In potato, banana and ginger, the plantlets arise from
the internodes present in the modified stem
(d) Water hyacinth, growing in the standing water, drains
oxygen from water that leads to the death of fishes
85 Mark the incorrect statement.
(a) Perennial species shows clear cut vegetative,
reproductive and senescent phases
(b) End of vegetative phase mark the beginning of
reproductive phase
(c) Bamboo species flower only once in their lifetime
(d) The reproductive phase is of variable duration in
different organisms
86 Choose the incorrect statement for events in sexual
reproduction.
(a) All sexually reproducing organisms exhibits events and
processess having fundamental similarity
(b) Structures associated with sexual reproduction vary
among different groups of organisms
(c) Pre-fertilisation, fertilisation and post-fertilisation is the
exact sequence of events occurring in sexual
reproduction
(d) None of the above
87 Which one of the following statements is incorrect?
(a) Gamete receive only one set of chromosomes
(b) Meiosis is a reductional division occurring in both
haploid and diploid organisms
(c) Male gametes are always produced in less quantity than
female gametes
(d) In seed plants, pollen grains are the carriers of male
gametes
88 Go through the following statements.
I. Cell division is a mode of reproduction in algae and
fungi.
II. Amoeba and Paramecium divide by fragmentation.
III. In yeast, cell division is unequal and small buds are
produced.
IV. Zoospores are macroscopic non-motile structures.
Choose the incorrect statements.
(a) I and III
(c) I, II and IV
(b) III and IV
(d) Only III
89 Read the following statements about asexual
reproduction and select the correct ones.
I. It involves a single parent.
II. It is slower than sexual reproduction.
III. It produces progeny that are genetically identical with
the parent, but not with one another.
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CHAPTER 01 > Reproduction in Organisms
IV. The progeny of asexual reproduction can be termed as
clones.
(a) I and II
(c) I and IV
(b) II and III
(d) I, III and IV
90 Read the following statements and select the correct
ones.
I. Conidia are the asexual propagules restricted to
kingdom–Fungi.
II. A piece of potato tuber having at least one eye (or
node) is capable of giving rise to a new plant.
III. Ginger propagates vegetatively with the help of its
underground roots.
IV. Fleshy buds which take part in vegetative propagation
are called bulbils, present in Dioscorea, Agave, etc.
(a) II and III
(c) I, II and IV
(b) I and IV
(d) I, II and III
91 Find out the incorrect statement.
I. Lifespans of organisms are necessarily correlated with
their sizes.
II. The sizes of crows and parrots are not very different,
but still their lifespans vary extremely.
III. A peepal tree has much shorter lifespan as compared to
a mango tree.
IV. Reproduction is essential for continuity of species on
the earth.
(a) I and III
(c) Only IV
(b) I, II and III
(d) II and III
92 Consider the following statements.
I. Many plants propagate vegetatively even though they
bear seeds.
II. Sweet potatoes multiply vegetatively by root tubers.
Select the correct option.
(a)
(b)
(c)
(d)
I is true, but II is false
Both I and II are false
I is false, but II is true
Both I and II are true
93 Read the following statements.
I. Organisms exhibiting external fertilisation show great
synchrony between the sexes and release a large
number of gametes.
II. A major disadvantage of external fertilisation is that
the offspring are extremely vulnerable to predators.
III. In gymnosperms, male gametes reach egg with the
help of water as a medium.
IV. Zygote is a vital link that ensures continuity of species
between organisms of one generation and the next.
V. Every sexually reproducing organisms begin their life
as a single-celled zygote.
Which of the above statements are correct?
(a) I, II and III
(c) I, II, IV and V
(b) I, II, III and V
(d) I, II, III and IV
11
94 Read the following statements.
I. Eichhornia contributes extra oxygen to the water
bodies which reduces the mortality of fishes.
II. Zingiber propagates vegetatively by tap roots.
III. Fleshy buds which take part in vegetative propagation
are called bulbils, e.g. Agave.
IV. A potato tuber having atleast one eye, i.e. axillary bud
can form a new plant.
V. Bryophyllum posssesss leaf buds.
Which of the above statements is/are correct?
(a)
(b)
(c)
(d)
I, II and III
III, IV and V
I, II and V
I, II, III, IV and V
95 Read the following statements.
I. The vegetative phase is of same duration in different
organisms.
II. Clear-cut vegetative, reproductive and senescent
phases can be observed in monocarpic plants.
III. Bambusa differs from Strobilanthes kunthiana
(Neelakurinji) in the length of juvenile phase and being
monocarpic.
IV. The end of juvenile/vegetative phase in angiosperms is
seen when they come to flower.
V. Sexual mode of reproduction is present in most
animals.
Which of the above statement is/are incorrect?
(a) II, IV and V
(c) III, IV and V
(b) II and III
(d) I and III
96 Read the following statements.
I. Interaction between hormones and certain
environmental factors regulate the reproductive
processes and the associated behavioural expression of
organisms.
II. In animals, but not in plants, hormones are responsible
for the transitions between juvenile, reproductive and
senescent phases.
III. After attainment of maturity, all sexually reproducing
organisms exhibit events and processes that have
remarkable fundamental similarity, though the
structure associated with sexual reproduction are
indeed very different.
IV. The post-fertilisation events include gametogenesis
and gamete transfer.
V. In majority of the sexually reproducing organisms, the
gametes produced are morphologically distinct types,
i.e. heterogametes.
Which of the above statements are correct?
(a)
(b)
(c)
(d)
I, III and V
I, II and IV
III, IV and V
II, III and V
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Master The NCERT > BIOLOGY (Vol-II )
12
III. Matching Type Questions
Codes
A
(a) 1
(b) 4
(c) 4
(d) 2
97 Match the following columns.
A.
B.
C.
D.
E.
Column I
(Asexual reproduction
types)
Binary fission
Zoospore
Conidium
Budding
Gemmules
Codes
A
(a) 1
(b) 2
(c) 1
(d) 1
B
4
1
2
4
C
5
4
3
3
D
3
3
4
2
Column II
(Examples)
1.
2.
3.
4.
5.
Algae
Amoeba
Hydra
Penicillium
Sponge
B. Dioecious
2. Fucus
C. Isogametes
3. Coconut
D. Heterogametes
4. Papaya
Codes
A
(a) 4
(c) 3
B
3
4
C
1
1
D
2
2
A
(b) 1
(d) 3
C
2
2
D
4
1
Column II
A.
External fertilisation
1. Human beings
B.
Internal fertilisation
2. Algae and fishes
C.
Ovipary
3. Bryophytes,
pteridophytes and birds
Codes
A
(a) 4
(c) 2
B
1
3
4
C
2
4
D
3
1
2n = 12
B.
Fruit fly
2.
2n = 16
C.
Onion
3.
2n = 46
D.
House fly
4.
2n = 08
A
(b) 3
(d) 4
B
2
4
1
4
C
4
3
4
2
D
3
2
3
1
B
1
2
C
4
1
Column II
(Reproduce by)
A.
Ginger
1. Tuber
B.
Yeast
2. Offset
C.
Potato
3. Rhizome
D.
Water hyacinth
4. Budding
Codes
A
(a) 4
(c) 3
B
1
4
C
2
1
D
3
2
Column I
(Floral parts)
D
2
3
Column II
A. Oestrus cycle
1. Spirogyra
B. Conjugation
2. Rose
C. Stem cuttings
3. Monkey, apes, humans
D. Menstrual cycle
4. Cows, sheeps, rats
A
(b) 3
(d) 4
B
1
2
C
4
1
D
2
3
103 Match the following columns.
Reptiles and birds
100 Match the following columns.
Column I
1.
Column I
(Organisms)
B
3
4
Column I
Vivipary
Human
102 Match the following columns.
99 Match the following columns.
D.
Column II
(Number of chromosomes)
A.
Codes
A
(a) 1
(b) 1
(c) 2
(d) 3
Column II
(Examples)
1. Cladophora
D
4
3
2
3
Column I
(Organisms)
98 Match the following columns.
A. Monoecious
C
2
2
3
4
101 Match the following columns.
E
2
5
5
5
Column I
(Terms)
B
3
1
1
1
Column II
(Converted to)
A.
Ovary
1. Pericarp
B.
Ovule
2. Perisperm
C.
Ovary wall
3. Fruit
D.
Nucellus
4. Seed
Codes
A
(a) 3
(b) 3
(c) 1
(d) 1
B
4
2
2
3
C
1
1
3
2
D
2
4
4
4
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CHAPTER 01 > Reproduction in Organisms
13
NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
104 A few statements with regard to sexual reproduction
are given below.
I. Sexual reproduction does not always require two
individuals.
II. Sexual reproduction generally involves gametic fusion.
III. Meiosis never occurs during sexual reproduction.
IV. External fertilisation is a rule during sexual
reproduction.
Choose the correct statements from the options given
below.
(a) I and IV (b) I and II (c) II and III
(d) II and IV
105 The term ‘clone’ cannot be applied to offspring
formed by sexual reproduction because
(a) offspring do not possess exact copies of parental DNA
(b) DNA of only one parent is copied and passed on to the
offspring
(c) offspring are formed at different times
(d) DNA of parent and offspring are completely different
106 The male gametes of rice plant have 12 chromosomes
in their nucleus. The chromosome number in the
female gamete, zygote and the cells of the seedling
will be, respectively
(a) 12, 24, 12
(c) 12, 24, 24
(b) 24, 12, 12
(d) 24, 12, 24
107 Amoeba and yeast reproduce asexually by fission and
budding, respectively because they are
(a) microscopic organisms (b) heterotrophic organisms
(c) unicellular organisms (d) uninucleate organisms
108 Appearance of vegetative propagules from the nodes
of plants such as sugarcane and ginger is mainly
because
(a)
(b)
(c)
(d)
nodes are shorter than internodes
nodes have meristematic cells
nodes are located near the soil
nodes have non-photosynthetic cells
109 Choose the correct statement from amongst the
following.
(a)
(b)
(c)
(d)
Dioecious organisms are seen only in animals
Dioecious organisms are seen only in plants
Dioecious organisms are seen in both plants and animals
Dioecious organisms are seen only in vertebrates
110 There are various types of reproduction. The type of
reproduction adopted by an organism depends on
(a)
(b)
(c)
(d)
the habitat and morphology of the organism
morphology of the organism
morphology and physiology of the organism
the organism’s habitat, physiology and genetic makeup
111 Which of the following is a post-fertilisation event in
flowering plants?
(a) Transfer of pollen grains (b) Embryo development
(d) Formation of pollen grains
(c) Formation of flower
112 A few statements describing certain features of
reproduction are given below.
I. Gametic fusion takes place.
II. Transfer of genetic material takes place.
III. Reduction division takes place.
IV. Progeny have some resemblance with parents.
Select the options that are true for both asexual and
sexual reproduction from the options given below.
(a) I and II
(b) II and III (c) II and IV (d) I and III
113 Asexual method of reproduction by binary fission is
common to which of the following?
I. Some eukaryotes
II. All eukaryotes
III. Some prokaryotes
IV. All prokaryotes
(a) I and II
(b) II and III (c) I and III
(d) III and IV
114 A multicellular, filamentous alga exhibits a type of
sexual life cycle in which the meiotic division occurs
after the formation of zygote. The adult filament of
this alga has
(a)
(b)
(c)
(d)
haploid vegetative cells and diploid gametangia
diploid vegetative cells and diploid gametangia
diploid vegetative cells and haploid gametangia
haploid vegetative cells and haploid gametangia
115 Given below are a few statements related to external
fertilisation. Choose the correct statements.
I. The male and female gametes are formed and released
simultaneously.
II. Only a few gametes are released into the medium.
III. Water is the medium in a majority of organisms
exhibiting external fertilisation.
IV. Offspring formed as a result of external fertilisation
have better chance of survival than those formed inside
an organism.
(a) III and IV (b) I and III (c) II and IV
(d) I and IV
116 The statements given below describe certain features
that are observed in the pistil of flowers.
I. Pistil may have many carpels.
II. Each carpel may have more than one ovule.
III. Each carpel has only one ovule.
IV. Pistil have only one carpel.
Choose the statements that are true from the options
given below.
(a) I and II
(b) I and III (c) II and IV
(d) III and IV
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117 Which of the following situations correctly describe
the similarity between an angiosperm egg and a
human egg?
I. Eggs of both are formed once in a lifetime.
II. Both the angiosperm egg and human egg are
stationary.
III. Both the angiosperm egg and human egg are motile
transported.
IV. Syngamy in both results in the formation of zygote.
Choose the correct answer from the options given
below.
(a)
(b)
(c)
(d)
119 Offspring formed by sexual reproduction exhibit
more variation than those formed by asexual
reproduction because
(a) sexual reproduction is a lengthy process
(b) gametes of parents have qualitatively different genetic
composition
(c) genetic material comes from parents of two different
species
(d) greater amount of DNA is involved in sexual
reproduction
120 There is no natural death in single-celled organisms
like Amoeba and bacteria because
II and IV
Only IV
III and IV
I and IV
(a)
(b)
(c)
(d)
118 Which of the following statements, support the view
that elaborate sexual reproductive process appeared
much later in the organic evolution?
I. Lower groups of organisms have simpler body design.
II. Asexual reproduction is common in lower groups.
III. Asexual reproduction is common in higher groups of
organisms.
IV. The high incidence of sexual reproduction in
angiosperms and vertebrates.
Choose the correct answer from the options given
below.
(a) I, II and III
(c) I, II and IV
they cannot reproduce sexually
they reproduce by binary fission
parental body is distributed among the offspring
they are microscopic
121 Identify the incorrect statement.
(a) In asexual reproduction, the offspring produced are
morphologically and genetically identical to the parent
(b) Zoospores are sexual reproductive structures
(c) In asexual reproduction, a single parent produces
offspring with or without the formation of gametes
(d) Conidia are asexual structures in Penicillium
122 The number of chromosomes in the shoot tip cells of
a maize plant is 20. The number of chromosomes in
the microspore mother cells of the same plant will
be
(a) 20
(c) 40
(b) I, III and IV
(d) II, III and IV
(b) 10
(d) 15
Answers
‡ Mastering NCERT with MCQs
1
11
21
31
41
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61
(a)
(b)
(b)
(c)
(c)
(a)
(c)
2
12
22
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(d)
(b)
(a)
(c)
(d)
(c)
(d)
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13
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(b)
(a)
(d)
(c)
(d)
(b)
(b)
4
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(d)
(a)
(b)
(d)
(d)
(b)
(a)
5
15
25
35
45
55
65
(c)
(b)
(b)
(c)
(b)
(a)
(a)
6
16
26
36
46
56
66
(a)
(d)
(b)
(a)
(d)
(d)
(a)
7
17
27
37
47
57
67
(c)
(b)
(c)
(a)
(d)
(c)
(d)
8
18
28
38
48
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(c)
(d)
(d)
(c)
(b)
(c)
(b)
9
19
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49
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(d)
(c)
(c)
(a)
(c)
(c)
(a)
10
20
30
40
50
60
70
(c)
(b)
(b)
(b)
(c)
(c)
(b)
‡ NEET Special Types Questions
71
81
91
101
(a)
(c)
(a)
(d)
72
82
92
102
(b)
(c)
(d)
(c)
73
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93
103
(d)
(c)
(c)
(a)
74 (a)
84 (c)
94 (b)
75 (b)
85 (a)
95 (d)
76 (c)
86 (d)
96 (a)
77 (a)
87 (c)
97 (b)
78 (c)
88 (c)
98 (c)
79 (d)
89 (c)
99 (c)
80 (a)
90 (c)
100 (b)
107 (c)
117 (b)
108 (b)
118 (c)
109 (c)
119 (b)
110 (d)
120 (c)
111 (b)
121 (b)
112 (c)
122 (a)
113 (c)
‡ NCERT Exemplar Questions
104 (b)
114 (d)
105 (a)
115 (b)
106 (c)
116 (a)
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CHAPTER 01 > Reproduction in Organisms
Answers & Explanations
organisms (e.g. Amoeba). It is due to the fact that they
divide and continue to live as their daughter cells.
3 (b) The organisms with the increasing order of their
lifespans are crow (15 years) < crocodile (60 years)
< parrot (140 years).
7 (c) Offspring produced by asexual (vegetative)
reproduction are called as clones. They are
morphologically and genetically similar individuals.
26 (b) The figure in option (b) represents water hyacinth.
28
29
10 (c) Cell division is the common mode of reproduction in
Monera and Protista as these contain single-celled
organisms. In this process, the cell divides by mitosis
into two parts and each part continues to live on as a
daughter cell.
13 (a) Zoospores are motile gametes. These are commonly
found in the fungi and plant kingdom, e.g.
Chlamydomonas.
30
14 (a) Conidia are the asexual reproductive structures found
in Penicillium. They are non-motile gametes which
develops singly or in chain on the parent body.
15 (b) Gemmule formation is a common mode of asexual
reproduction in sponges. In this, the buds are formed
within the parent body and later get released into the
environment to form a new organism.
31
19 (c) Option (c) contains the incorrectly matched pair. It
can be corrected as
Binary fission is observed in Amoeba and Sargassum
reproduces through fragmentation. Rest of the pairs are
correctly matched.
20 (b) Offsets are produced by mitotic divisions. These are
one internode long runners that occur in some aquatic
plants. Breaking of offsets helps in vegetative
propagation. These give rise to new plants, e.g.
Eichhornia.
22 (a) Option (a) contains the correctly matched pair.
Rest of the matches are incorrect and can be corrected as
l
l
l
Ginger propagates by rhizome formation.
Chlamydomonas reproduces by zoospores.
Yeast reproduces by budding.
32 (c) Sexual reproduction involves formation of the male
33
34
35
24 (b) Antherozoid is not a vegetative propagule. In
majority of the sexually reproducing organisms, the
motile male gamete is called as antherozoid or sperm
whereas the other options represent vegetative
propagules which have the capability of giving rise to
new offspring.
25 (b) In Agave, bulbils are modified floral buds that
develop on the flowering axis, so chromosome number
in a cell of bulbil will be equal to that of the leaf cell of
Agave, i.e. n = X.
This plant was introduced in India because of its
beautiful flowers and the shape of its leaves. This plant
can propagate at a very fast rate, spreading all over the
water body in a short amount of time. However, this
plant becomes invasive and is very difficult to get rid of.
(d) In both potato and sugarcane, new plantlets arise
from the nodes present in their modified stems.
(c) Sexual reproduction produces individuals with new
combinations of recombined chromosomes. This
produces variations among offspring. When conditions
become more stressful, an organism switches to sexual
mode of reproduction so as to produce offspring with
variations. These enable the offspring to adapt to the
stressful conditions and successfully survive and
reproduce.
(b) In grafting technique, parts of two plants are joined
to form a composite plant. One part represents the
strong root system called stock and the other part
having better flower or fruit yield on shoot is called the
scion. Hence, the fruit produced in such plants would
have the genotype of the scion.
(c) Sexual reproduction brings about variation through
genetic recombinations due to the participation of two
parents. In this, the random union of gametes
contributes in forming new combinations of characters.
37
43
and female gametes, either by the same individual or
by different individuals of the opposite sex.
(c) The growth phase of an organism before attaining
sexual maturity is referred to as juvenile phase and
pre-reproductive phase. In plants it is known as
vegetative phase.
(d) Before reproducing sexually, organisms reach a
stage of growth and maturity in their life which is
known as juvenile phase or pre-reproductive phase.
The end of this phase, marks the beginning of the
reproductive phase and this phase finally leads to old
age or senescent phase.
(c) Bamboo plants are perennial, monocarpic plants.
They flower only once in their lifetime, usually after
50-100 years producing a large number of fruits and
then these plants die.
(a) Generally, oestrus cycle takes place in the seasonal
breeders, e.g. non-primates. It is the cyclic change in
the activity of ovaries and accessory duct during the
reproductive (seasonal) period.
(d) Male gametes are called antherozoids in case of
lower organisms like fungi and algae, and in higher
organisms like mammals, reptiles, etc., these are called
sperms.
Answers & Explanations
2 (d) No individual is immortal except some single-celled
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44 (d) Hermaphrodite/bisexual/monoecious/homothallic
45
46
51
52
53
54
59
Answers & Explanations
60
63
64
are terms used when both the male and female
reproductive organs are present in same organism.
Hermaphrodite is used for animals. Bisexual and
monoecious are used for both animal and plant.
Homothallic is used for fungi.
(b) In figure P, B–represents the antheridium (male sex
organ) of Chara. In figure Q, C–represents the testis
sac with testis of earthworm.
(d) Heterothallic/dioecious/unisexual are terms used
when the sexes, i.e. male and female reproductive parts
are present on different organisms. Heterothallic is used
for fungi. Unisexual and dioecious used for both
animals and plants.
(a) Irrespective of the fact, whether the organism is
haploid or diploid, it has haploid gametes.
In haploid parents, mitosis produces haploid gametes.
In diploid parents, meiosis produces haploid gametes.
(c) Gamete mother cells are called gamete producing
cells. In these, meiotic cell division takes place for the
production of haploid gametes. These are also called
meiocytes (diploid).
(b) Option (b) represents the incorrect combination. It
can be corrected as
16 and 8 are the chromosome numbers in meiocyte and
gametes, respectively in Allium cepa (onion). Potato
has 48 and 24 chromosomes in meiocyte and in
gametes, respectively.
Rest all options are correct combinations.
(b) In the given diagram, three figures are shown. First
figure indicates the fusion of male and female gametes.
Second figure indicates the formed zygote because
there are two nuclei visible in completely fused
condition.
Third figure indicates a complete new cell after fusion
is completed. Now, it can be called as a new individual.
(c) Syngamy or Fertilisation refers to the phenomenon
of the haploid fusion of male and female gametes that
leads to the formation of a diploid cell.
(c) Parthenogenesis is the process by which the female
gamete develops into embryo without fertilisation. It is
of two types, i.e. haploid and diploid. In the former,
embryo develops from haploid egg and in the later a
diploid egg develops into embryo.
(b) In internal fertilisation, fusion of gametes
(syngamy) takes place inside the female reproductive
tract. This process provides direct protection from the
environment to the developing progeny.
(a) The presence of diploid zygote is universal in all
sexually reproducing organisms irrespective of the fact
that, the parents are haploid or diploid.
In haploid parent condition, the diploid zygote
undergoes meiosis and becomes haploid body again,
while in diploid organisms, the diploid zygote changes
to diploid individual after undergoing mitosis.
65 (a) During fertilisation two haploid cells, a female and a
67
68
71
72
73
74
75
76
77
male gamete combine to form a single diploid cell (2n)
called zygote, from where every sexually reproducing
organism begin its life.
(d) Option (d) contains the incorrect match. It can be
corrected as
In viviparous animals, zygote develops inside the body
of female.
Rest of the pairs are correct.
(b) In viviparous animals, the zygote develops into a
young one inside the body of female organism. Thus, the
chances of survival of young ones are greater in these
animals because these young ones are provided with
proper embryo care and protection.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
In asexual mode of reproduction, there is no variation
and the genetic constituent of offspring remains the
same.
Because in this process, offspring is produced without
the involvement of gametic fusion (syngamy) and
involves only mitotic cell division.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Asexual reproduction involves the participation of a
single parent to produce an offspring. As a result, the
offspring produced are morphologically and genetically
similar to one another and also to their parents and can
be referred to as clone.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Reproduction by zoospores occurs in some lower fungi,
e.g. Albugo.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Zygote is the product of fusion of two gametes. It is a
vital link that ensures the continuity of species between
the organisms of one generation and the next.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Vegetative reproduction is a kind of asexual
reproduction in plants in which offspring are formed by
vegetative propagules like tuber, sucker, runner, etc.,
rather than by fusion of gametes.
(c) Assertion is true, but Reason is false and it can be
corrected as
Perennial plants have a long lifespan. Hence, it becomes
very difficult to define and study their vegetative,
reproductive and senescent phases.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Meiocytes (gamete mother cell) are specialised cells in
diploid organisms that undergo meiosis to form haploid
gametes. Gametes have only one set of chromosome as
that of meiocytes.
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CHAPTER 01 > Reproduction in Organisms
79
80
81
82
83
corrected as
Dioecious is the term used to describe unisexual
condition. Dioecious plants have their reproductive
structures on different plants, e.g. papaya and
Marchantia.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
In external fertilisation, fertilisation or syngamy occurs
outside the female body.
(a) Both Assertion and Reason are true and Reason is the
correct explanation of Assertion.
In flowering plants, the zygote is formed inside the
ovule and after fertilisation, the zygote develops into
embryo and the ovules into seeds.
(c) The statement in option (c) is incorrect and it can be
corrected as
During post-fertilisation event, ovule develops into
seed not embryo sac.
Rest of the statements regarding post-fertilisation
development in flowering plants are correct.
(c) Statement in option (c) is incorrect. It can be
corrected as
Gemmules are asexual structures, produced by
organisms (e.g. sponge) during unfavourable condition
by the process of internal budding.
Rest of the statements are correct about gemmules.
(c) Statement in option (c) is correct. Rest of the
statements are incorrect and can be corrected as
l
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l
All the individuals of a species have different lifespan.
Smaller organisms do not always have a shorter
lifespan and vice-versa.
Some organisms may have a lifespan of several
hundred years.
84 (c) Statement in option (c) is incorrect. It can be
corrected as
In potato, banana and ginger, new plantlets always arise
from the nodes of the modified stem.
Rest of the statements are correct.
85 (a) Statement in option (a) is incorrect. It can be
corrected as
Perennial species do not show clear cut vegetative,
reproductive and senescent phases.
Rest of the statements are correct.
87 (c) Statement in option (c) is incorrect. It can be
corrected as
The number of male gametes produced is several
thousand times more than the number of female
gametes produced.
Rest of the statements are correct.
88 (c) Statements I, II and IV are incorrect and can be
corrected as.
l
Cell division is a mode of reproduction in monerans
and protists.
l
l
Amoeba and Paramecium mostly divide by binary
fission.
The zoospores are microscopic and motile asexual
reproductive bodies.
Remaining statement III is correct.
89 (c) Statements I and IV are correct. But statements II
and III are incorrect and can be corrected as
l
l
Asexual reproduction is faster than sexual reproduction.
Asexual reproduction produces progeny that are
genetically identical with one another as well as with
the parent.
90 (c) Statements I, II and IV are correct, but statement III
is incorrect and can be corrected as
l
Ginger propagates vegetatively with the help of
rhizome. Rhizomes are main underground stems which
store food for perennation during unfavourable
conditions. These have buds for the formation of new
aerial shoots during favourable conditions.
91 (a) Statements II and IV are correct. But statements
I and III are incorrect and can be corrected as
l
l
Lifespans of organisms are not necessarily correlated
with their sizes.
A mango tree has a much storter lifespan as compared
to a peepal tree.
93 (c) Statements I, II, IV and V are correct. Statement III
is incorrect and can be corrected as
In gymnosperms, the non-motile male gametes are
carried to the female gamete through pollen tube.
94 (b) Statements III, IV and V are correct. Statements I
and II are incorrect and can be corrected as
l
l
Eichhornia drains oxygen from the water bodies which
increases the mortality of fishes.
Zingiber propagates vegetatively by rhizome
(underground stem).
95 (d) Statements I and III are incorrect and can be
corrected as
l
l
The vegetative phase is of different durartion in
different organisms.
Bambusa differs from Strobilanthes kunthiana in the
length of juvenile phase, but both plants are
monocarpic.
Rest of the statements are correct.
96 (a) Statements I, III and V are correct. Statements II and
IV are incorrect and can be corrected as
l
l
In both plants and animals, hormones are responsible
for transitions between the three phases, i.e. juvenile,
reproductive and senescent.
The pre-fertilisation events include gametogenesis and
gamete transfer.
104 (b) Statements I and II are correct. Statements III and IV
are incorrect and can be corrected as
l
l
Meiosis is required for the production of haploid
gametes during sexual reproduction.
External fertilisation is not a rule during sexual
reproduction, it can occur internally also.
Answers & Explanations
78 (c) Assertion is true, but Reason is false and it can be
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105 (a) The term ‘clone’ cannot be applied to offspring
106
107
108
109
110
Answers & Explanations
111
112
formed by sexual reproduction because offspring do not
possess exact copies of parental DNA. Offspring
produced by sexual reproduction has half DNA from
one parent and half from another parent, thus is not an
exact copy of any one parent, i.e. it is not a clone. But
there DNA is still similar to their parents DNA.
(c) In female gamete of rice plant the chromosome
number will be same as that of the male gamete (12).
Zygote is formed by fertilisation of male and female
gametes thus, the chromosome number will be 24 (2n).
A seedling is young plant sporophyte developing out of
embryo. So, chromosome number will be 24 (2n).
Thus, option (c) is correct.
(c) Unicellular organisms (like Amoeba and yeast) have
a relatively simple body organisation. So, asexual mode
of reproduction is common in them because by asexual
reproduction unicellular organisms can multiply very
fast. In Amoeba, it occurs by binary fission and in yeast
by budding.
(b) The appearance of vegetative propagules from the
nodes of plants like sugarcane and ginger is due to the
presence of meristematic cells at the nodes. These cells
have the capacity of rapid cell division, thus are
responsible for growth and development of tissues and
organs in plants.
(c) Statement in option (c) is correct. Dioecious is the
term used to describe unisexual condition in plants and
animals, e.g. Marchantia (plants) and cockroach
(animals).
(d) There is a large diversity in the biological world and
each organism has evolved its own mechanism to
multiply and produce offspring. The type of
reproduction adopted by an organism depends on the
organism’s habitat, its internal physiology, genetic
makeup and several other factors.
(b) Embryo development takes place after the event of
fertilisation, i.e. fusion of male and female gametes (n)
and results in the formation of zygote (2n). Thus, it is a
post-fertilisation event. Rest of the events takes place
before the occurrence of fertilisation and hence, are
pre-fertilisation events.
(c) Statements II and IV are true for both asexual and
sexual reproduction. But gametic fusion and reduction
division take place only in sexual reproduction.
114 (d) Option (d) is correct and can be explained as
In a multicellular filamentous alga (e.g. Ulothrix), the
sexual life cycle have meiotic division after the zygote
(2n) formation. It mean meiosis in zygote will produce
haploid spores or vegetative cells (n ) and when these
vegetative cells undergo asexual reproduction the
gametophyte or gametangia formed will be haploid (n )
too.
115 (b) Statements I and III are correct regarding external
fertilisation. Statements II and IV are incorrect and can
be corrected as
l
l
A large number of gametes are released into the
medium (water) to increase the chances of fertilisation.
The chances of survival of offspring from external
fertilisation are lesser than those of internal fertilisation
as they face more risk from predators.
116 (a) Statements I and II are correct. Statements III and
IV are incorrect and can be corrected as
Gynoecium is the female part of the flower, a unit of
which is called pistil. A pistil may have one or more
than one carpels (monocarpellary, bicarpellary, etc).
Each carpel may have more than one ovules.
119 (b) In sexual reproduction genetic variation is observed.
In this mode of reproduction, gametes of two parents
(opposite sex) having qualitatively different genetic
composition participate in the reproductive process, (i.e.
fusion of male and female gametes).
This gives rise to a new individual having an entirely
new genetic makeup.
120 (c) There is no natural death in single-celled organisms
like Amoeba and bacteria. It is so, because of asexual
reproduction, the body of parent is divided or
distributed into daughter cells or offspring. In such
organisms, reproduction occurs by cell division where
the parent cell divides into two halves.
121 (b) Statement in option (b) is incorrect and can be
corrected as
Zoospores are asexually reproducing structures.
Rest of the statements are correct.
122 (a) Shoot tip cells and microspore mother cells both are
diploid in maize plant. If number of chromosomes in
shoot tip cell is (2n) = 20, then number of chromosomes
in microspore mother cell will be (2n) = 20.
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CHAPTER > 02
Sexual Reproduction
in Flowering Plants
NEET
Å
Å
KEY NOTES
Sexual reproduction occurs in all flowering plants, i.e.
angiosperms. It is the process of fusion of haploid gametes,
resulting in the production of a diploid zygote. Which
ultimately develops into new organism.
Stamen, Microsporangium and
Pollen Grain
Different types of adaptations are shown in angiosperms by
the diversified structures of the inflorescences, flowers and
floral parts, to ensure the formation of the end products of
sexual reproduction, i.e. the fruits and seeds.
Stamen
The male gametophyte includes the following parts
Å
It is the male reproductive unit of angiosperms. It consists
of two parts
n
Flower
Å
Å
It is the modified condensed shoot arising on the axil of small
leaf-like structure called bract and consists of four whorls or
floral appendages, attached on the receptacle.
Of these, the two lower whorls, i.e. calyx and corolla are sterile
and considered as non-essential/accessory/helping whorls and
the two upper whorls, i.e. androecium and gynoecium are
fertile and are considered as essential or reproductive whorls.
Pre-fertilisation: Structures and
Events
Å
Several hormonal and structural changes in plants lead to the
differentiation and further development of the floral
primordium.
Å
Inflorescences are formed which bear the floral buds and then
the flowers.
Å
In the flower, the androecium (male reproductive part) and
gynoecium (female reproductive part) differentiate and
develop to form the male and female gametophyte.
n
The long and slender stalk called the filament.
The terminal, generally bilobed structure called the
anther.
Å
The proximal end of the filament is attached to the
thalamus or the petal (i.e. epipetalous) of the flower. The
number and length of the stamens are variable in flowers of
different species.
Å
A typical angiospermic anther is a bilobed structure with
each lobe having two theca (dithecous) and are separated
by a longitudinal groove running lengthwise.
Å
In a cross section, the anther is a tetragonal structure
consisting of four microsporangia located at the corners,
two in each lobe. Later, the microsporangia develop and
become pollen sacs, which are packed with pollen grains.
Structure of Microsporangium
Å
A typical microsporangium is surrounded by four wall
layers, i.e. the epidermis, endothecium, middle layers and
the tapetum. The outer three wall layers are protective in
function and help in dehiscence of anther to release pollen
grains.
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20
Å
Tapetum (innermost layer) nourishes the developing
microspores or pollen grains and the cells of tapetum
possess dense cytoplasm and generally have more than
one nucleus.
Middle
layers
Exine Intine
Pollen grain
Å
The vegetative cell is larger, has abundant reserve food
material and a large nucleus, which is irregular in shape.
Whereas, the generative cell is small, spindle-shaped and
floats in the cytoplasm of the vegetative cell.
Å
Pollen grains are generally shed at this 2-celled stage in over
60% of angiosperms. In the remaining species, the
generative cell divides mitotically and gives rise to two
male gametes before pollen grains are shed (3-celled stage).
Å
Pollen grains of several plant species may cause severe
allergies and bronchial infections leading to asthma,
bronchitis, etc., e.g. Parthenium or carrot grass came to
India as a contaminant with imported wheat, became
ubiquitous in occurrence and caused pollen allergy.
Å
Pollen grains are rich in nutrients. In Western countries,
large number of pollen products in the form of tablets and
syrups are used to increase the performance of athletes
and race horses.
Å
Viability of pollen depends on temperature and
humidity. It varies from species to species, e.g. 30 minutes
in case of wheat, rice and several months as in some
members of Solanaceae, Rosaceae, Leguminosae, etc.
Å
It is possible to store pollen grains for years in liquid
nitrogen (–196°C) in pollen banks for later use in plant
breeding programmes.
(b)
When the anther is young, a group of compactly arranged
homogenous cells called the sporogenous tissue occupies
the centre of each microsporangium.
Microsporogenesis
Å
Å
Å
Each cell of the sporogenous tissue is a potential
Pollen Mother Cell (PMC) or microspore mother cell and
can give rise to microspore tetrad. This process of
formation of microspore from a pollen mother cell
through the process of meiosis is called
microsporogenesis.
As the anthers mature and dehydrate, the microspores
dissociate from one another and form tetrad and develop
into pollen grains. Inside each microsporangium, several
thousands of microspores or pollen grains are formed that
are released with the dehiscence of anther.
In general, dehiscence of anther occurs through the
rupture of the anther lobe walls, which causes the release
of the pollen grains.
Male Gametophyte (Pollen Grain)
Å
Å
Å
A pollen grain is a partly germinated microspore
representing the male gametophyte. It is a haploid,
uninucleate and minute spore produced in large numbers
by meiosis in the microspore mother cell. They vary in
their size, shape, colour, design, etc., from species to
species.
Pollen grains are generally spherical measuring about
25-50 micrometre in diameter. It has a two layered wall
(also called sporoderm), outer hard layer exine is made up
of sporopollenin. It is the most resistant organic material
as it can withstand high temperature as well as strong
acids and alkali. No known enzyme can degrade it. Thus,
pollens are well-preserved as fossils.
Pollen grains have prominent distal aperture for
germination called germ pore, where sporopollenin is
absent. The inner layer intine is thin and chiefly composed
of cellulose and pectin.
NEET
Generative cell
Vegetative cell
(a) Transverse section of a young anther (b) Enlarged view of a
microsporangium showing four wall layers
Å
Each mature pollen grain in angiosperms has two cells, the
generative cell and vegetative cell.
Epidermis
Endothecium
Middle layers
Microspore
mother cells
Tapetum
Connective
Epidermis
Endothecium
Sporogenous
tissue
Tapetum
(a)
Å
The Pistil, Megasporangium (Ovule)
and Embryo Sac
The female gametophyte includes the following parts
Pistil
Å
The pistil or gynoecium represents the female reproductive
part of the flower. It may consist of one pistil or carpel
(monocarpellary), two carpels (bicarpellary), three carpels
(tricarpellary) or many carpels (multicarpellary).
Å
Pistil may be syncarpous (i.e. more than one pistils are
fused together) as in Papaver, Solanum, etc., or apocarpous,
i.e. (carpels remain free) as in Michelia, rose, etc.
Å
A typical pistil consists of the hollow basal swollen ovary,
the elongated style and the terminal stigma (serves as a
landing platform for pollen grains). Inside the ovary, is the
ovarian cavity (locule) in which placenta is located.
Megasporangium (ovules) arises from placenta.
KEY NOTES
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
Structure of Megasporangium (Ovule)
Å
Å
Å
n
The ovule is an integumented megasporangium within which
meiosis and megaspore formation takes place. It is attached to
the placenta by means of a stalk called funicle. It develops
into a seed after fertilisation. The junction between an ovule
and funicle is called hilum, which later becomes a scar on the
seed.
n
Each ovule has one or two protective envelops called
integuments, which encircle the ovule except at the tip where
a small opening called micropyle is located.
Three cells present towards the micropylar end are
grouped together and constitute the egg apparatus,
i.e. two synergids and one egg cell.
Three cells of the chalazal end are called the
antipodals. The large central cell is formed by the
fusion of 2 polar nuclei. Thus, a typical angiospermic
embryo sac or female gametophyte at maturity
consists of eight nuclei and seven cells.
Chalazal end
Antipodals
The basal part of an ovule just opposite to micropyle is
called chalaza. Enclosed within the integuments is a mass of
cells called nucellus, whose cells are rich in reserve food
materials. An ovule generally has a single embryo sac or
female gametophyte, developed from a megaspore through
reductional division and located within the nucellus.
Polar nuclei
Central cell
Egg
Synergids
Megasporogenesis
Å
The process of formation of megaspores from Megaspore
Mother Cell or MMC (diploid) is called megasporogenesis.
Å
It occurs inside the nucellus of the developing ovule of
angiosperms. The process begins very early when nucellus
is not completely surrounded by the integuments.
Å
The MMC (a large cell containing dense cytoplasm and a
prominent nucleus) enlarges in size and divides by meiosis.
It first divides transversely into two cells called megaspore
dyad.
Å
These two cells again divide transversely forming a linear
row of four haploid cells which is called megaspore tetrad
or linear tetrad.
Female Gametophyte (Embryo Sac)
Å
In general, the development of embryo sac is monosporic, e.g.
in Polygonum. In this type of development, only one megaspore
situated towards chalazal end remains functional, while the
remaining three megaspores gradually degenerate and finally
disappear.
Å
Following are the different stages in development of female
gametophyte
n
n
n
n
The functional haploid megaspore is the first cell of
female gametophyte of angiosperms.
Its nucleus undergoes mitotic division to form 2-nuclei that
move to opposite poles forming 2-nucleate embryo sac.
The 2-nucleate embryo sac undergoes two more
sequential mitotic divisions giving rise to the 4-nucleate
stage and later 8-nucleate stage of embryo sac. This stage
comprises of a micropylar end and a chalazal end with
four nuclei at each end.
Six of the eight nuclei are surrounded by cell walls and
get organised into cells. The remaining two nuclei, called
polar nuclei are situated below the egg apparatus in the
large central cell.
Filiform apparatus
Micropylar end
A diagrammatic representation of mature embryo sac
Pollination
The transfer of pollen grains from the anther of the stamen
to the receptive stigma of the carpel/pistil is called
pollination.
Depending upon the source of pollen grains, pollination is
of following three types
Å
Autogamy (Self-pollination) It is the kind of pollination
achieved within the same flower. The pollens from the
anthers of a flower are transferred to the stigma of the
same flower, e.g. wheat, rice, pea, etc.
Å
Plants show following adaptations for autogamy.
n
n
Cleistogamous flowers These are closed flowers and
their anthers and stigma lie close to each other, e.g.
Viola (common pansy), Mirabilis, Commelina and
Oxalis. Almost all the cleistogamous flowers are
invariably autogamous as there is no chance of
cross-pollination.
Chasmogamous flowers These are opened flowers
with exposed sex organs. On these, pollens from
another flower can land on the stigma as well, e.g.
Catharanthus and Mirabilis.
Å
Geitonogamy It is the kind of self-pollination where the
pollen grains from the anther of a flower are transferred
to the stigma of another flower borne on the same plant,
but at different branches. It usually occurs in plants
which show monoecious condition, e.g. Cucurbita.
Å
Xenogamy (Cross-pollination) It involves the transfer of
pollen grains from the anther of one plant to the stigma
of another plant. This is the only type of pollination
which brings genetically different types of pollen grains
to the stigma during pollination, e.g. papaya, maize, etc.
NEET
KEY NOTES
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22
Agents of Pollination
Outbreeding Devices
Pollination in plants occurs via various abiotic and biotic
agents as follows
These are developed by bisexual flowers to avoid
self-pollination and promote cross-pollination because
continuous self-pollination results in poor yield and poor
quality of seeds. This phenomenon is called inbreeding
depression. Such devices are
1. Abiotic agents of pollination are wind (anemophily)
and water (hydrophily).
(a) Wind pollinated flowers have
Å
Light and non-sticky pollen grains.
Å
Generally a single ovule in each ovary and
numerous flowers packed into an inflorescence,
e.g. corn cob.
Well-exposed stamens and large feathery stigma
to trap air-borne pollen grains.
Å
Wind pollination is common in grass, maize, date
palm, etc.
Å
(b) Water pollination occurs in mostly monocotyledons
(in about 30 genera). Some examples of water
pollinated plants are Hydrilla, Vallisneria and
Zostera.
Å
Å
Å
Å
Self-sterility
Unisexuality
Chasmogamous flowers
Å
Protandry (Maturation of male parts prior to female parts)
Å
Protogyny (Maturation of female parts before male parts)
Å
Note In castor and maize, unisexuality prevents autogamy. In
papaya, it prevents both autogamy and
geitonogamy.
Pollen-Pistil Interaction
Å
The female flower reaches the surface of water by
the long stalk and pollen grains are released onto
the surface of water, e.g. Vallisneria.
It involves pollen recognition followed by inhibition of
pollen (sexual incompatibility) or promotion of pollen
(sexual compatibility).
Å
In most of the water pollinated species, pollen
grains are protected from wetting by
mucilaginous covering.
Pistil accepts the compatible pollen of the same species and
rejects the incompatible pollen either of the same species or
of other species.
Å
After compatible pollination, the pollen grain germinates
and produces pollen tube (carries two male gametes) which
moves through the style and reaches to the egg, which is
known as ‘siphonogamy’ in angiosperms.
Insect pollinated flowers are generally large,
colourful, fragrant and rich in nectar.
Å
The pollen grains and stigmatic surface are sticky.
Å
The animal pollinated flowers offer certain rewards
to the pollinators. Some of them are
Å
Å
It consists of all the events from the deposition of pollen on
stigma to entry of pollen tube into the ovule.
Å
n
Dichogamy (Production of male and female reproductive
parts at different times)
Å
In majority of aquatic plants, the flowers emerge
above the level of water and are pollinated by
insects or wind, e.g. water hyacinth and water
lily.
2. Biotic agents of pollination are insects (entomophily),
bats (chiropterophily), snails (malacophily), birds
(ornithophily) etc.
n
Å
Artificial Hybridisation
Å
It is the crossing of different species to generate a progeny
containing all the desirable characters. These are
commercially superior varieties.
Å
It is used for crop improvement programmes. This process
involves
Emasculation anther removal before dehiscence.
Bagging covering emasculated flower in a bag to
prevent its contamination by unwanted pollen grains.
These offer nectar and (edible) pollen grains.
Some species provide safe place for laying eggs,
e.g. Amorphophallus and Yucca.
A relationship exists between a species of moth
and the plant Yucca, where both the species cannot
complete their life cycles without each other. The
moth deposits its eggs in the locule of the ovary
and the flower, in turn, gets pollinated by the
moth. The larvae of the moth come out of the egg
as the seeds start developing.
Many insects may consume pollen or the nectar
without bringing about pollination. Such floral
visitors are referred to as pollen/nectar robbers.
NEET
n
n
Å
After the maturity of the stigma of the bagged flowers,
collected pollen grains are dusted over it. The flowers are
then rebagged at fruits are allowed to develop.
Double Fertilisation
It occurs after the pollen tube reaches the ovary. It is the
characteristic of angiosperms.
Å
The pollen tube releases two male gametes into the
cytoplasm of a synergid.
KEY NOTES
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
Å
One of the male gamete fuses with egg cell (syngamy), which
results in the formation of zygote.
Å
The second male gamete fuses with the two polar nuclei to
form a triploid Primary Endosperm Nucleus (PEN). This is
called triple fusion.
Since, two fusions, i.e. syngamy and triple fusion occur in an
embryo sac, this is called double fertilisation.
Central cell after the triple fusion called as Primary
Endosperm Cell (PEC) develops into the endosperm and
zygote develops into an embryo.
Å
Å
Post-fertilisation : Structures
and Events
n
n
Seed
Å
Å
Å
Å
Endosperm
Å
Å
It is a mass of nutritive cell produced as a result of triple
fusion through mitotic division.
On the basis of development, it is of three types
In nuclear type, which is a common method, the Primary
Endosperm Nucleus (PEN) undergoes repeated mitotic
division without cytokinesis. At this stage, the endosperm
is called free- nuclear endosperm.
In cellular type, cell wall formation occurs and the
endosperm becomes cellular. The number of free nuclei
formed before cellularisation varies greatly, e.g. in
coconut the water is free nuclear endosperm and
surrounding white kernel is cellular endosperm.
In helobial type endosperm formation, one half of
endosperm is nuclear type and other half is cellular type.
n
Å
n
n
Fruits
Å
n
Embryo
It develops at the micropylar end of the embryo sac where
the zygote is situated.
Å
Embryo formation occurs when certain amount of
endosperm is formed, because endosperm provides nutrition
for embryo development.
Ovary develops into fruit and ovule matures into seeds.
The wall of ovary becomes wall of fruit, i.e. pericarp.
In true fruits, ovary contributes to fruit formation.
Fruits may be fleshy such as, guava, orange, mango
or dry such as groundnut, mustard, etc.
In false fruits, thalamus (swollen end of stems that
bear floral parts) also contributes to fruit formation,
e.g. apple, cashewnut, etc.
Parthenocarpic fruits develop without fertilisation
and are seedless, e.g. banana.
Seedless fruits can be reproduced artificially through
the application of growth hormones.
n
n
Å
It is the fertilised ovule formed inside the fruits.
It consists of seed coat (hardened ovule integuments),
cotyledons and an embryonal axis.
Two types of mature seeds are
Non-albuminous in which endosperm is completely
consumed, e.g. in pea and groundnut.
Albuminous that retain part of endosperm, e.g.
wheat, maize and barley.
In some seeds, remnants of nucellus are persistant which
is called perisperm, e.g. black pepper and beet root.
Micropyle of the ovule remains as the small pore in the
seed coat. It facilitates the entry of oxygen and water
into seed during germination.
Dormancy In this condition, water content reduces,
seed become dry, metabolic activities of embryo slow
down and the seed may enter into a state of inactivity
called dormancy. If conditions are not favourable seed
will not germinate and it may germinate, if conditions
are favourable.
n
Development of endosperm, embryo, maturation of ovule into
seed and ovary into fruit are collectively termed as
post-fertilisation events.
Å
Embryonal axis has the radicle on its lower end
(hypocotyl), the radicle is covered by an
undifferentiated sheath called coleorhiza.
At the upper end (epicotyl), the embryonal axis has
plumule. It is covered by a hollow foliar sheath called
coleoptile.
n
n
n
n
Å
Zygote divides by mitosis and forms proembryo.
This results in the formation of globular and
heart-shaped embryo that finally becomes horse
shoe-shaped (mature embryo) having cotyledon.
Apomixis and Polyembryony
Å
Dicot embryo consists of two cotyledons and an embryonal
axis between them
n
n
Å
n
The part of embryonal axis above the level of cotyledons
is the epicotyl which becomes plumule (shoot).
The part of embryonal axis below the level of cotyledons
is the hypocotyl which becomes radicle or root tip.
Monocot embryo consists of only one cotyledon (called
scutellum in grass family), e.g. rice, maize plants, etc.
Å
Apomixis is the special mechanism to produce seeds
without fertilisation, e.g. grass and is a form of asexual
reproduction that mimics sexual reproduction and is
useful for the hybrid industry. The modes by which
apomictic seeds can be produced are agamospermy,
adventive embryony, etc.
Polyembryony is the presence of more than one embryo
in a seed. In many Citrus and Mangifera varieties, some
of the nucellar cells surrounding the embryo sac start
dividing, protrude into the embryo sac and develop into
embryos.
NEET
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24
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1
~ Flower and Development of Gametes
1 Identify A to G in following figure and answer
accordingly.
(a) pollen
(c) anther
E D
F
4 The terminal structure of stamen is called
(b) filament
(d) All of these
5 The lengthwise running groove on anther which
separate theca is called
G
C
(a)
(b)
(c)
(d)
B
rupture line
line of dehiscence
suture of anther
None of the above
6 Number of microsporangia in an angiospermic
A
anther is
(a) A–Ovary, B–Filament, C–Sepal, D–Petal, E–Style,
F–Stigma, G–Anther
(b) A–Sepal, B–Ovary, C–Petal, D–Filament, E–Anther,
F–Stigma, G–Style
(c) A–Ovary, B–Sepal, C–Filament, D–Petal, E–Anther,
F–Stigma, G–Style
(d) A–Petal, B–Anther, C–Stigma, D–Style, E–Filament,
F–Sepal, G–Ovary
2 Find odd one out.
(a) 1
(b) 2
(a) pollens
(c) megagametes
(d) 4
(b) microgametes
(d) pollen sac
8 Identify A to E in the following diagram.
A
B
C
JIPMER 2019
(b) Stigma
(d) Ovary
(a) Stamen
(c) Style
(c) 3
7 Microsporangium develops into
D
3 Identify A to D in the following diagram.
E
D
C
B
A
(a) A – Filament (stalk) , B – Pollen sac,
C – Pollen grain, D – Line of dehiscence
(b) A – Filament (stalk), B – Pollen sac,
C – Line of dehiscence, D – Pollen grain
(c) A – Line of dehiscence, B – Filament (stalk) ,
C – Pollen sac, D – Pollen grains
(d) A – Filament (stalk), B – Line of dehiscence,
C – Pollen sac, D – Pollen grains
(a) A–Tapetum, B–Microspore mother cell, C–Middle
layer, D–Endothecium, E–Epidermis
(b) A–Epidermis, B–Middle layer, C–Microspore mother
cell, D–Tapetum, E–Endothecium
(c) A–Middle layer, B–Epidermis, C–Tapetum,
D–Microspore mother cell, E–Endothecium
(d) A–Epidermis, B–Endothecium, C–Middle layer,
D–Microspore mother cell, E–Tapetum
9 The innermost layer of microsporangium is
(a) tapetum
(c) middle layer
(b) endothecium
(d) epidermis
10 Centre of each microsporangium is occupied by
(a)
(b)
(c)
(d)
sporogenous tissue
tapetum
central tissue
microspore mother cell
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11 Identify A to E in the following diagram.
25
18 Intine is made up of
(a) cellulose
(c) Both (a) and (b)
A
B
C
D
F
E
(a) A–Epidermis, B–Endodermis, C–Connective,
D–Sporogenous tissue, E–Middle layers, F–Tapetum
(b) A–Endodermis, B–Connective, C–Epidermis,
D–Tapetum, E–Sporogenous tissue, F–Middle layers
(c) A–Tapetum, B–Middle layers, C–Sporogenous tissue,
D–Connective, E–Endodermis, F–Epidermis
(d) A–Connective, B–Epidermis, C–Endothecium,
D–Sporogenous tissue, E–Tapetum, F–Middle layers
12 The outermost wall layer of microsporangium in
anther is
(a) endothecium
(c) middle layer
(b) tapetum
(d) epidermis
13 Which of the following perform microsporogenesis?
(a) Microspore mother cell (b) Pollen mother cell
(c) Both (a) and (b)
(d) None of these
14 The process of formation of microspores from pollen
mother cell through … A… is called … B... .
Microspores are arranged in … C … . As the anthers
matures and dehydrate, microspores develop into the
…D… .
Fill in the blanks A to D.
(a) A–pollen grains, B–microspore tetrad,
C–microsporogenesis, D–meiosis
(b) A–microspore tetrad, B–microsporogenesis,
C–meiosis, D–pollen grains
(c) A–microsporogenesis, B–microspore tetrad,
C–pollen grain, D–meiosis
(d) A–meiosis, B–microsporogenesis, C–microspore tetrad,
D–pollen grains
15 Microspore tetrad (pollen grains) is the result of
(a) mitotic cell division
(c) Both (a) and (b)
(b) meiotic cell division
(d) None of these
16 Dehiscence of anther in mesophytes is caused by
(a) hydration of anthers
(c) mechanical injury
(b) dehydration of anthers
(d) None of these
17 Pollens have two prominant walls which are …A…
19 Exine of pollen is made up of
(a)
(b)
(c)
(d)
sporopollenin
sporogenous tissue
spongiform tissue
inorganic material
20 Patterns and designs of exine of pollen grains are the
characteristic features of
(a) species of plant
(c) order of plants
(b) genus of plants
(d) None of these
21 Hardest substance in plant kingdom is
(a) saple
(c) sporopollenin
JIPMER 2019
(b) corolla
(d) anther
22 The sporopollenin is non-degradable because
(a)
(b)
(c)
(d)
it can withstand strong acids
it is resistant at very high temperature
no enzyme degrade it
All of the above
23 Which of the following has proved helpful in
preserving pollen as fossils?
(a) Oil content
(c) Pollenkitt
NEET 2018
(b) Cellulosic intine
(d) Sporopollenin
24 The functions of germ pore is/are
(a)
(b)
(c)
(d)
emergence of radicle
absorption of water for seed germination
initiation of pollen tube
All of the above
25 Identify the structures marked A to F in the given
diagram.
B
A
C
E
D
F
(a) A–Asymmetric nucleus, B–Nucleus, C–Generative cell,
D–Vegetative cell, E–Pollen, F–Pollen tetrad
(b) A–Pollen tetrad, B–Pollen, C–Generative cell,
D–Vegetative cell, E–Asymmetric spindle, F–Nucleus
(c) A–Pollen tetrad, B–Vacuole, C–Nucleus,
D–Asymmetric spindle, E–Vegetative cell,
F–Generative cell
(d) A–Vacuole, B–Nucleus, C–Pollen tetrad, D–Vegetative
cell, E–Asymmetric spindle, F–Generative cell
26 When the pollen grain is mature, it contains two cells,
and …B… . Here A and B refers to
the … A … and … B ….
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
A–intine, B–protein coat
A–exine, B–intine
A–sporopollenin, B–intine
A–sporopollenin, B–exine
(b) pectin
(d) protein
A–generative cell, B–spore mother cell
A–vegetative cell, B–spore mother cell
A–spore mother cell, B–male gamete
A–vegetative cell, B–generative cell
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Master The NCERT > BIOLOGY (Vol-II )
26
27 To achieve 3-celled stage in angiosperms, which cell
35 Identify A to I in the given diagram.
of the pollen grain divides to form two male gametes ?
(a)
(b)
(c)
(d)
A
B
C
D
E
NEET 2018
Vegetative cell
Generative cell
Microspore mother cell
None of the above
F
G
H
28 60% of the angiosperms shed their pollens at the
(a) 2-celled stage
(c) 4-celled stage
(b) 3-celled stage
(d) 1-celled stage
29 Male gametophyte in angiosperms produces
I
CBSE-AIPMT 2015
(a)
(b)
(c)
(d)
two sperms and a vegetative cell
single sperm and a vegetative cell
single sperm and two vegetative cell
three sperms
30 Pollen tablets are available in the market for
CBSE-AIPMT 2014
(a) in vitro fertilisation
(c) supplementing food
(b) breeding programmes
(d) ex situ conservation
31 Pollen grains can be stored for several years in liquid
nitrogen having temperature of
(a) – 196°C (b) – 80°C (c) – 120°C
NEET 2018
(d) – 160°C
32 In the given diagram of pistil, in which part
fertilisation takes place?
(a) A–Chalazal end, B–Embryo sac, C–Nucellus, D–Inner
integuments, E–Outer integuments, F–Micropylar pole,
G–Micropyle, H–Funicle, I–Hilum
(b) A–Inner integuments, B–Nucellus, C–Embryo sac,
D–Chalazal end, E–Hilum, F–Funicle, G–Micropyle,
H–Micropylar end, I–Outer integuments
(c) A–Hilum, B–Funicle, C–Micropyle, D–Micropylar
pole, E–Outer integuments, F–Inner integuments,
G–Nucellus, H–Embryo sac, I–Chalazal pole
(d) A–Micropylar end, B–Micropyle, C–Funicle, D–Hilum,
E–Outer integuments, F–Inner integuments,
G–Nucellus, H–Embryo sac, I–Chalazal end
36 The stalk which joins ovule and placenta is called
(a) funicle
(c) chalaza
A
(b) hilum
(d) micropyle
37 The ovule of an angiosperm is technically
B
equivalent to
NEET 2016
(b) megasporophyll
(a) megasporangium
(c) megaspore mother cell (d) megaspore
38 An ovule is a
C
D
(a) D
(b) C
(c) B
(d) A
33 Identify the type of pistil in the diagram.
(a)
(b)
(c)
(d)
differentiated megasporangium
dedifferentiated megasporangium
integumented megasporangium
redifferentiated megasporangium
39 Chalazal pole is present
Stigma
(a)
(b)
(c)
(d)
opposite to micropyle
at the origin of integuments
opposite to nucellus
near the embryo sac
40 Mass of cells enclosed by integuments is called
(a)
(b)
(c)
(d)
(a) nucellus
(c) ova
Multicarpellary, apocarpous
Multicarpellary, syncarpous
Multicarpellary, pistillate
Monocarpellary, apocarpous
41 Embryo sac is also called
34 Identify the type of pistil in the diagram alongside.
(a)
(b)
(c)
(d)
Monocarpellary, syncarpous
Monocarpellary, apocarpous
Multicarpellary, syncarpous
Multicarpellary, apocarpus
(b) embryo
(d) pollen
Carpels
(a) female gamete
(c) female gametophyte
(b) synergids
(d) egg of angiosperm
42 Megasporogenesis is
(a)
(b)
(c)
(d)
formation of fruits
formation of seeds
formation of megaspores
Both (b) and (c)
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
43 Megaspore mother cell is found near the region of
(a) micropyle
(c) nucellus
(a)
(b)
(c)
(d)
50 Identify the labelling of given diagrams.
(b) chalaza
(d) integuments
44 In majority of angiosperms
egg has a filiform apparatus
there are numerous antipodal cells
reduction division occurs in the megaspore mother cells
a small central cell is present in the embryo sac
45 In angiosperms, microsporogenesis and
(a)
(b)
(c)
(d)
CBSE-AIPMT 2015
occur in anther
form gametes without further divisions
involves meiosis
occur in ovule
46 Functional megaspore in an angiosperm develops into
(a) ovule
(c) embryo sac
NEET 2017
(b) endosperm
(d) embryo
47 Which is the most common type of embryo sac in
angiosperms?
(a)
(b)
(c)
(d)
NEET (Odisha) 2019
Tetrasporic with one mitotic stage of divisions
Monosporic with three sequential mitotic divisions
Monosporic with two sequential mitotic divisions
Bisporic with two sequential mitotic divisions
A–MMC, B–Megaspore dyad, C–Nucellus, D–Nucleus
A–Nucellus, B–Megaspore dyad, C–Nucellus, D–MMC
A–Nucellus, B–MMC, C–Nucellus, D–Megaspore dyad
A–MMC, B–Nucellus, C–Megaspore dyad, D–Nucleus
51 Identify A to E in the diagram given below.
(a) A–Antipodal, B–2 polar nuclei, C–Central
cell, D–Egg, E–Synergids
(b) A–Antipodal, B–Central cell, C–2 polar
nuclei, D–Egg, E–Synergids
(c) A–2 polar nuclei, B–Central cell,
C–Antipodal cell, D–Egg, E–Synergids
(d) A–Synergids, B–Egg, C–Central cell,
D–2 polar nuclei, E–Antipodal cell
(a) 1–1–2–3
(c) 2–1–1–3
49 Identify A to F in the diagram given below.
A
B
C
D
E
(b) 2–1–3–2
(d) 3–2–1–2
53 Identify A to F in the diagram given below.
Degeneration
of three
cells
B
(a)
(b)
(c)
(d)
central cell → antipodal cell follows the order
(b) unisporic
(d) disporic
A
D
B
52 In embryo sac, the number of synergid → egg cell →
48 Single megasporic development is called
(a) single sporic
(c) monosporic
C
A
NEET 2016
megasporogenesis
27
F
Only one
remains
functional
E
D
C
B
C
A
F
E
D
(a) A–Mitosis, B–Meiosis-I, C–Meiosis-II, D–Mitosis,
E–Meiosis, F–Meiosis
(b) A–Meiosis-I, B– Meiosis-II, C–Mitosis, D–Mitosis,
E–Mitosis, F–Embryo sac
(c) A–Embryo, B–Meiosis-I, C–Meiosis-II, D–Mitosis,
E–Mitosis, F–Mitosis
(d) A–Mitosis, B–Mitosis, C–Mitosis, D–Meiosis,
E–Meiosis, F–Meiosis
(a) A–Egg, B–Filiform apparatus, C–Synergid,
D–Antipodals, E–Polar nuclei, F–Central cell
(b) A–Egg, B–Synergid, C–Filiform apparatus,
D–Antipodals, E–Central cell, F–Polar nuclei
(c) A–Central cell, B–Egg, C–Synergid, D–Antipodals,
E–Filiform apparatus, F–Polar nuclei
(d) A–Filiform apparatus, B–Synergid, C–Egg, D–Central
cell, E–Polar nuclei, F–Antipodals
54 Filiform apparatus are
(a)
(b)
(c)
(d)
special cellular thickenings at antipodal cell
special cellular thickenings at the micropylar end
special cellular thickenings at synergid cells
special cellular thickenings at nuclear end
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Master The NCERT > BIOLOGY (Vol-II )
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59 Egg apparatus consists of
55 Function of filiform apparatus is to
CBSE-AIPMT 2014, 08
(a) recognise the suitable pollen at stigma
(b) stimulate division of generative cell
(c) produce nectar
(d) guide the entry of pollen tube
(b) 7
(c) 6
chalazal end are called
(d) 5
(a) nucellar cells
(c) antipodal cells
57 How many cells are found in female gametophyte?
(a) 6
(c) 7
(b) 8
(d) 5
(b) synergids
(d) None of these
61 In an angiospermic anatropous ovule, the embryo sac
contains certain cells at the micropylar end. These are
called
58 Two nuclei within a single cell is
(a) antipodal cell
(c) central cell
2 synergids + 2 eggs
2 synergids + 2 eggs
2 synergids + 1 egg
2 synergids + 4 eggs
60 In an embryo sac of anatropous ovule, cells present at
56 How many nuclei are found in female gametophyte?
(a) 8
(a)
(b)
(c)
(d)
(b) chalazal cell
(d) synergid cell
(a) synergids
(c) nucellar cells
(b) antipodal cells
(d) None of these
TOPIC 2 ~ Pollination
68 Geitonogamy involves
62 Autogamy stands for
(a)
(b)
(c)
(d)
63 Cleistogamous flowers are strictly autogamous
because they remain
(a)
(b)
(c)
(d)
always open
always close
always fragrance
are brighty coloured
69 Transfer of pollen grains from the anther to stigma of
another flower of different plant is called
(a) geitonogamy
(c) chasmogamy
64 Identify the type of flower A and B.
(a) A–Cleistogamous;
B–Chasmogamous
(b) A–Homogamous;
B–Heterogamous
(c) A–Chasmogamous;
B–Cleistogamous
(d) A–Heterogamous;
B–Homogamous
flowering plant is/ are
(a) water
(c) Both (a) and (b)
(b) wind
(d) None of these
71 Characteristic of wind pollinated pollens is, they are
B
open flower
closed flower
large flower
geitonogamy flower
(a)
(b)
(c)
(d)
non-sticky
light
produced in large number
All of the above
72 The feathery long stigma is found in
(a) rice
(b) maize
(c) sugarcane (d) None of these
73 Flowers, which have single ovule in the ovary and are
66 Advantage of cleistogamy is
NEET 2013
(a) water
(a) lilies
CBSE-AIPMT 2012
(b) Zostera
(d) Fig
(b) bee
(c) wind
74 Wind pollination is common in
67 Even in the absence of pollinating agents seed-setting
is assured in
packed into inflorescence are usually pollinated by
NEET 2017
(a) higher genetic variability
(b) more vigorous offspring
(c) no dependence on pollinators
(d) vivipary
(a) Commelina
(c) Salvia
(b) xenogamy
(d) cleistogamy
70 The most common abiotic pollinating agency in
A
65 In chasmogamy pollination takes place in
(a)
(b)
(c)
(d)
CBSE-AIPMT 2014, 10, 1994
(a) fertilisation of a flower by the pollen from another
flower of the same plant
(b) fertilisation of a flower by the pollen from the same
flower
(c) fertilisation of a flower by the pollen from a flower of
another plant in the same population
(d) fertilisation of a flower by the pollen from a flower of
another plant belonging to a distant population
pollination in same flower
pollination between different plants
pollination in two flowers of same plant
division in embryo
(b) grasses
(d) bat
CBSE-AIPMT 2015, 14
(c) orchids
(d) legumes
75 Pollination in water hyacinth and water lily is brought
about by the agency of
(a) water
(c) birds
NEET 2016
(b) insects or wind
(d) bats
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
76 What type of pollination takes place in Vallisneria?
NEET 2019
(a) Pollination occurs in submerged condition by water
(b) Flowers emerge above surface of water and pollination
occurs by insects
(c) Flowers emerge above water surface and pollen is
carried by wind
(d) Male flowers are carried by water currents to female
flowers at the surface of water
77 Pollen grain of water pollinated plants are coated by
covering to prevent it from wetting
(a) mucilage
(c) exine
(b) cuticle
(d) intine
78 Wind pollinated and water pollinated flowers
(a)
(b)
(c)
(d)
are colourful
are non-colourful
are small in size
produce nectar
JIPMER 2018
anemophily
entomophily
malacophily
zoophily
80 Attractants and rewards are required for
(a)
(b)
(c)
(d)
NEET 2017
anemophily
entomophily
hydrophily
cleistogamy
81 Which one of the following plants shows a very close
relationship with a species of moth, where none of the
two can complete its life cycle without the other?
NEET 2018
(a) Banana
(c) Hydrilla
(b) Yucca
(d) Viola
82 Continued self-pollination results in
(a)
(b)
(c)
(d)
85 In which of the following, both autogamy and
geitonogamy are prevented?
NEET (Odisha) 2019, CBSE-AIPMT 2012
(a) Wheat
(b) Papaya
(c) Castor
(d) Maize
86 Identify A to F in the given diagram.
(a) A–Pollen tube, B–Ovary, C–Ovule,
D–Antipodal cell, E–Pollen grain,
F–Polar nuclei
(b) A–Polar nuclei, B–Antipodal cell,
C–Ovule, D–Ovary, E–Pollen tube,
F–Pollen grain
(c) A–Pollen grain, B–Pollen tube,
C–Ovary, D–Ovule, E–Antipodal cell,
F– Polar nuclei
(d) A–Antipodal cell, B–Ovule, C–Ovary,
D–Polar nuclei, E–Pollen grain,
F–Pollen tube
A
B
C
E
D
F
87 Diagram showing entry of pollen tube to the embryo
79 Pollenkitt is present in
(a)
(b)
(c)
(d)
29
inbreeding depression
out breeding depression
hybrid vigour
better result in offspring
sac. Identify A to G in the diagram.
(a) A–Synergid, B–Filiform
apparatus, C–Male gamete, F
A
D–Plasma membrane,
G
E–Central cell, F–Egg
nucleus, G–Vegetative
B
nucleus
(b) A–Filiform apparatus,
C
B–Central cell, C–Egg
nucleus, D–Vegetative
D
nucleus, E–Male gamete,
E
F–Synergid, G–Plasma
membrane
(c) A–Plasma membrane, B–Synergid, C–Filiform
apparatus, D–Male gametes, E–Vegetative nucleus,
F–Central cell, G–Egg nucleus
(d) A–Central cell, B–Egg nucleus, C–Vegetative nucleus,
D–Male gametes, E–Synergid, F–Plasma membrane,
G-Filiform apparatus
88 Diagram showing discharge of gametes in the egg
apparatus. Identify A, B and C.
A
83 Device to discourage self-pollination or increase
B
cross-pollination is
(a) pollen release and stigma receptivity are not
synchronised
(b) anther and stigma placed at different position
(c) same height of stamen and stigma
(d) Both (a) and (b)
C
84 A dioecious flowering plant prevents both NEET 2017
(a)
(b)
(c)
(d)
autogamy and xenogamy
autogamy and geitonogamy
geitonogamy and xenogamy
cleistogamy and xenogamy
(a)
(b)
(c)
(d)
A–Polar nuclei, B–Female gametes, C–Synergid cell
A–Male gametes, B–Synergid cell, C–Polar nuclei
A–Synergid cell, B–Male gametes, C–Polar nuclei
A–Polar nuclei, B–Male gametes, C–Synergid cell
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Master The NCERT > BIOLOGY (Vol-II )
30
91 The process of removal of anther from the flower bud
89 Generally pollen tube enters through
(a)
(b)
(c)
(d)
before it dehisces is called as
micropylar region
antipodal region
chalazal end
nuclear region
(a) emasculation
(c) embryo rescue
90 The ability of the pistil to recognise the pollen
followed by its acceptance or rejection is the result of
a continuous dialogue between pollen grain and the
pistil.
Which of the following chemicals mainly takes part
in this interaction.
(a) Nucleotides
(c) Minerals
(b) Proteins
(d) Lipid or Inulin
AIIMS 2019
(b) bagging
(d) budding
92 For artificial hybridisation experiment in bisexual
flower, which of the sequence is correct?
(a) Bagging → Emasculation → Cross-pollination
→ Rebagging
(b) Emasculation→ Bagging → Cross-pollination
→ Rebagging
(c) Cross-pollination → Bagging → Emasculation
→ Rebagging
(d) Self-pollination → Bagging → Emasculation
→ Rebagging
TOPIC 3 ~ Double Fertilisation and Development of Endosperm
93 Double fertilisation is
NEET 2018
(a) fusion of two male gametes with one egg
(b) fusion of one male gamete with two polar nuclei
(c) fusion of two male gametes of pollen tube with two
different eggs
(d) syngamy and triple fusion
94 Double fertilisation is exhibited by
(a) gymnosperms
(c) fungi
95
I.
III.
V.
VII.
96 What is the fate of the male gametes discharged in the
NEET 2019
(a) All fuse with the egg
(b) One fuses with the egg, other(s) fuse(s) with synergid
nucleus
(c) One fuses with the egg and other fuses with central cell
nuclei
(d) One fuses with the egg other(s) degenerate(s) in the
synergid
97 Find out A, B and C in the flowchart given below.
B
n
2n
A–Embryo, B–Male gamete, C–Female gamete
A–Male gamete, B–Female gamete, C–Embryo
A–Female gamete, B–Embryo, C–Male gamete
A–Male gamete, B–Embryo, C–Female gamete
99 How many number of nuclei are involved in
(b) II, IV, VI and VII
(d) II, IV, III and I
A
B
n
C
(a)
(b)
(c)
(d)
Out of the seven names given above, find out haploid
cells.
synergid?
A
n
2n
II. Egg cell
IV. Polar nuclei
VI. Nucellar cell
(a) I, II, IV and V
(c) I, II, III and V
98 Find out A, B and C in the flowchart given below.
NEET 2017
(b) algae
(d) angiosperms
Antipodal cell
Synergid cell
Male gamete
Central cell
(c) A–Male gamete, B–Polar nuclei, C–Endosperm
(d) A–Female gamete, B–Endosperm, C–Male gamete
C
3n
(a) A–Female gamete, B–Male gamete, C–Endosperm
(b) A−Endosperm, B–Female gamete, C–Male gamete
fertilisation?
(a) 1
(b) 1 + 1
(c) 2 + 1
(d) None of these
100 The total number of nuclei involved in triple fusion
is/are
(a) 2
(b) 3
(c) 4
(d) 1
101 Syngamy and triple fusion is called …A… . The
central cell becomes …B… develop into …C… and
zygote develops into …D… .
A, B, C and D in the above statements are
(a) A–fusion, B–haploid, C–diploid cell, D–embryo
(b) A–double fertilisation, B–PEC, C–endosperm,
D–embryo
(c) A–embryo, B–endosperm, C–PEC, D–diploid cell
(d) A–PEC, B–endosperm, C–syngamy, D–fertilisation
102 If stem has 2n = 10 number of chromosomes then
find out
A – number of chromosome in endosperm.
B – number of chromosome in egg cell.
C – number of chromosome in polar nuclei, respectively.
(a) 15, 15, 20
(c) 15, 5, 10
(b) 10, 15, 20
(d) 10, 5, 15
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
(a) A–Degenerating antipodal cell, B–Primary endosperm
nucleus, C–Primary endosperm cell, D–Synergid cell,
E–Zygote
(b) A–Synergid cell, B–Antipodal cell, C–Zygote,
D–Endosperm cell, E–Chalazal cell
(c) A–Degenerating synergids, B–Zygote, C–Primary
endosperm cell, D–Primary endosperm nucleus,
E–Degenerating antipodal cell
(d) A–Zygote, B–Synergid, C–Primary endosperm cell,
D–Primary endosperm nucleus, E–Degenerating
antipodal cell
103 If endosperm has 36 number of chromosomes then
find out the chromosome number of male and female
gamete.
(a) 18, 18
(b) 17, 18
(c) 20, 20
(d) 12, 12
104 PEC (Primary Endosperm Cell) is formed
(a) after triple fusion
(b) before triple fusion
(c) at the time of syngamy (d) always persisted
105 In an angiosperm, male plant is diploid and female
plant is tetraploid then endosperm will be
(a) haploid
(c) tetraploid
(b) triploid
(d) pentaploid
106 In angiosperm, pollen tube librates their male gametes
108 Out of the following choose the post-fertilisation
event(s).
into the
(a) central cell
(c) egg cell
31
(a) Endospermogenesis
(c) Both (a) and (b)
(b) antipodal cell
(d) synergids
107 In the given fertilised embryo sac, identify A to E.
(b) Embryogenesis
(d) Megasporogenesis
109 The morphological nature of the edible part of coconut
is
A
NEET 2017
(a) perisperm
(c) endosperm
B
(b) cotyledon
(d) pericarp
110 Coconut water from a tender coconut is
(a)
(b)
(c)
(d)
C
D
immature embryo
free-nuclear endosperm
innermost layers of the seed coat
degenerated nucellus
CBSE-AIPMT 2015
111 Endosperm is consumed by developing embryo in the
seed of
E
(a) pea
(c) coconut
(b) maize
(d) castor
TOPIC 4~ Embryo, Seed and Fruit Formation
112 Identify the different stages in embryogenesis in the given diagram A, B, C, D, E, F and G.
F
E
G
A
(a)
(b)
(c)
(d)
B
C
D
A–2-celled stage, B–Heart-shaped embryo, C–Globular embryo, D–Mature embryo, E–Radicle, F–Suspensor, G–Cotyledon
A–2-celled stage, B–Mature embryo, C–Heart-shaped embryo, D–Globular embryo, E–Cotyledon, F–Radicle, G–Suspensor
A–2-celled stage, B–Globular embryo, C–Heart-shaped embryo, D–Mature embryo, E–Suspensor, F–Radicle, G–Cotyledon
A–Mature embryo, B–Heart-shaped embryo, C–Globular embryo, D–2-celled stage, E–Suspensor, F–Cotyledon, G–Radicle
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113 Identify the A to E in the following diagram of typical
dicot embryo.
A
B
C
D
E
(a) A–Cotyledons, B–Hypocotyl, C–Plumule, D–Root cap,
E–Radicle
(b) A–Radicle, B–Root cap, C–Plumule, D–Hypocotyl,
E–Cotyledons
(c) A–Hypocotyl, B–Cotyledons, C–Plumule, D–Radicle,
E–Root cap
(d) A–Plumule, B–Cotyledons, C–Hypocotyl, D–Radicle,
E–Root cap
114 In figure given below, find out the type of seed and
identify coleoptile, coleorhiza and epiblast.
A
116 A typical dicotyledonous embryo consist of an …A…
axis and …B… cotyledons.
The portion of embryonal axis above the level of
cotyledons is …C… which terminates with the …D…
or stem tip.
A, B, C and D in the above statement are
(a)
(b)
(c)
(d)
A–plumule, B–epicotyl, C–cotyledons, D–embryonal
A–embryonal, B–two, C–epicotyl, D–plumule
A–embryonal, B–epicotyl, C–cotyledons, D–plumule
A–embryonal, B–plumule, C–cotyledons, D–epicotyl
117 The cylindrical portion below the cotyledons is
…A… that terminates to …B… and its tip is called
…C… . A, B and C here refers to
(a)
(b)
(c)
(d)
A–radicle, B–hypocotyl, C–root cap
A–root cap, B–radicle, C–hypocotyl
A–hypocotyl, B–root cap, C–radicle
A–hypocotyl, B–radicle, C–root cap
118 The wheat grain has an embryo with one large,
shield-shaped cotyledon known as CBSE-AIPMT 2015
(a) epiblast
(c) scutellum
(b) coleorhiza
(d) caleoptile
119 Number of seeds are equal to the
B
C
D
(a) number of ovules
(c) Both (a) and (b)
(b) number of ovaries
(d) None of these
120 Persistent nucellus in the seed is known as NEET 2019
(a) perisperm (b) hilum (c) tegmen
(d) chalaza
121 Which is most crucial for seed storage?
E
F
G
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
Dehydration and dormancy
Endosperm and water
Least amount of development
Endosperm in large quantity
122 True fruit is directly derived from
Monocots–A , B and C
Dicots–F, A and C
Monocots–B, G and D
Dicots–D, E and A
(a) stem
(c) ovary
(b) root
(d) None of these
123 False fruit is a fruit in which
115 Identify the parts labelled as A to D in structure of
seed given below.
(a)
(b)
(c)
(d)
only ovary take part in fruit development
only embryo take part in fruit development
only chalazal cells take part in fruit development
ovary and other floral part are included in fruit
development
124 Thalamus contributes in the fruit formation in
A
B
C
D
(a)
(b)
(c)
(d)
A–Coleoptile, B–Plumule, C–Radicle, D–Coleorhiza
A–Plumule, B–Coleoptile, C–Coleorhiza, D–Radicle
A–Coleorhiza, B–Radicle, C–Plumule, D–Coleoptile
A–Radicle, B–Plumule, C–Coleoptile, D–Coleorhiza
(a) apple
(c) cashewnut
(b) strawberry
(d) All of these
125 The world’s oldest viable seed, excavated from Arctic
Tundra is of
(a) lupine
(b) Ficus
(c) date palm
(d) Phoenix
126 Viability of date palm (Phoenix dactylifera) seed is
(a) 2000 yrs
(c) 500 yrs
(b) 1000 yrs
(d) 100 yrs
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
33
TOPIC 5 ~ Apomixis and Polyembryony
127 Seed formation without fertilisation in flowering
plants involves the process of
(a) budding
(c) apomixis
131 Vegetative/Asexual reproduction and apomixis are
common to each other in
NEET 2016
(a)
(b)
(c)
(d)
(b) somatic hybridisation
(d) sporulation
128 Type of cell division takes place in apomixis is
(a) reductional
(c) Both (a) and (b)
(b) meiosis
(d) mitosis
132 Nucellar polyembryony is reported in
(a) Gossypium
(c) Brassica
129 Ovules contain many embryo in
(a) Citrus
(c) mango
(b) apple
(d) Both (a) and (c)
(b) Triticum
(d) Citrus
133 Apomictic embryos in Citrus arise from
(a)
(b)
(c)
(d)
130 Occurrence of more than one embryo is called
(a) polyembryony
(c) parthenogenesis
type of cell division
clone nature of offspring
Both (a) and (b)
only in dicot plant
(b) embryony
(d) fertilisation
synergids
maternal sporophytic tissue in ovule
antipodal cell
haploid egg
NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
138 Assertion (A) Pollen grain of angiosperm is
■ Direction (Q. No. 134-148) In each of the following
questions, a statement of Assertion (A) is given followed
by corresponding statement of Reason (R). Of the
statements, mark the correct answer as
(a) If both A and R are true and R is correct explanation of A
(b) If both A and R are true, but R is not the correct
explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true
139
140
134 Assertion (A) Gynoecium consists of pistil.
Reason (R) It represents the male reproductive part in
flowering plants.
135 Assertion (A) Meiosis is the cell division which
occurs in the sexually reproducing organisms.
Reason (R) Meiotic cell division results into two cells
having exactly same genetic makeup.
136 Assertion (A) Flowers are the structures related to
sexual reproduction in flowering plants.
Reason (R) Various embryological processes of
plants occur in a flower.
137 Assertion (A) Megaspore mother cell undergoes
meiosis to produce four megaspores.
Reason (R) Megaspore mother cell and megaspore
both are haploid.
141
142
143
144
considered as the male gametophyte.
Reason (R) Pollen grain contains stigma, style and
ovary.
Assertion (A) Geitonogamy is genetically similar to
autogamy.
Reason (R) In geitonogamy, pollen grains come from
the same plant.
Assertion (A) Cleistogamous flowers produce
assured seed set in the absence of pollinators.
Reason (R) Cleistogamous flowers do not open at all.
Assertion (A) Removal of anthers is first step in
artificial hybridisation.
Reason (R) It prevents contamination of anthers.
Assertion (A) Endosperm development preceds
embryo development.
Reason (R) It assures nutrition to the developing
embryo.
Assertion (A) Non-albuminous seeds have no
residual endosperm.
Reason (R) The endosperm is completely consumed
during embryo development.
Assertion (A) Mango is a false fruit.
Reason (R) The thalamus also contributes to fruit
formation in false fruits.
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145 Assertion (A) Some fruits are seedless or contain
non-viable seeds.
Reason (R) They are produced without fertilisation.
146 Assertion (A) In apomixis, plants of new genetic
variations are not produced.
Reason (R) In apomixis, reductional division
takes place.
147 Assertion Parthenocarpy involves the formation of
seedless fruits.
AIIMS 2019
Reason Apomixis occurs without fertilisation.
148 Assertion In apomixis, the plants of new genetic
sequence are produced.
AIIMS 2019
Reason In apomixis, two organisms of same genetic
sequence meet.
II. Statement Based Questions
149 Read the following statements and choose the correct
ones.
I. Non-essential floral organs in a flower are sepals and
petals.
II. Stamens represent microsporophylls.
III. A dithecious anther consists of four microsporangia
two in each lobe.
IV. The anther wall has middle layer lieing between
endothecium and tapetum.
(a) I and II
(c) III and IV
(b) II and III
(d) I, II, III and IV
150 Which one of the following statement is correct?
(a)
(b)
(c)
(d)
Hard outer layer of pollen is called intine
Sporogenous tissue is haploid
Endothecium produces the microspores
Tapetum nourishes the developing pollen
NEET 2013
151 Self-incompatibility is a device for
I. ensuring cross-pollination.
II. preventing self-fertilisation.
III. ensuring self-fertilisation.
IV. genetic control for self-fertilisation.
Choose the correct statements from those given
above.
(a) I, II and III
(c) I, III and IV
(b) I, II, III and IV
(d) I, II and IV
152 Which of the following statement(s) is/are correct?
I. The stigma serves as a landing platform for pollen
grains.
II. Ovarian cavity is also known as ovarian locule and is
present inside the ovary.
III. Placenta is located inside the ovarian cavity.
IV. The ovule is attached to the placenta by funicle.
(a) I, II and III
(c) I and III
(b) I, II and IV
(d) I, II, III and IV
153 Read the following statements.
I. Generative cell is bigger and contains abundant food
reserve.
II. Vegetative cell is small and floats in the cytoplasm of
the generative cell.
III. In angiosperms various stages of reductional divisions
can be studied in young anthers.
IV. Hilum represents the junctions between ovule and
funicle.
Choose the option with correct set of statements.
(a) I and II
(c) II and IV
(b) I and III
(d) III and IV
154 Read the following statements and choose the correct
statements.
I. Heterostyly as a contrivance for cross-pollination is
found in Primula vulgaris.
II. Cleistogamous flower is present in Commelina.
III. Tallest flower are of Amorphophallus.
IV. In monoecious condition, both male and female
flowers are borne on same plant, an example of such
plant is Cucurbita.
(a)
(b)
(c)
(d)
I and II
II and III
III and IV
I, II, III and IV
155 Read the following statements and choose the correct
ones.
I. Mature ovules in which micropyle comes to lie close to
the funiculus the ovule is anatropous.
II. When micropyle, chalaza and hilum lie in a straight
line the ovule is said to be orthotropous.
III. Megasporangium along with its protective integument
is called ovule.
(a) I and II
(c) I and III
(b) II and III
(d) I, II and III
156 Consider the following statements.
I. Pollination by bats is known as chiropterophily.
II. Pollination by ants is known as ornithophily.
(a)
(b)
(c)
(d)
Both statements I and II are true
Statements I is true, but II is false
Statements I is false, but II is true
Both statements I and II are false
157 Which one of the following statement is incorrect
about pollination?
(a) Anemophily is by wind and occurs in grasses and date
palm
(b) Hydrophily is by water and occurs in Zostera,
Vallisneria and Ceratophyllum
(c) Entomophily is by insects and occurs in rose, jasmine,
Salvia, etc.
(d) Ornithophily is by birds and occurs in Adansonia
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
158 Which of the following statement(s) is/are correct
about Parthenium (carrot grass)?
(a) Parthenium came into India as a contaminant with
imported wheat
(b) It has became ubiquitous in occurrence
(c) It causes pollen allergy
(d) All of the above
159 Choose the incorrect statement from the following.
(a) Long ribbon-like pollen grains are seen in some aquatic
plants
(b) In some insect species, the floral reward for pollination
is the safe place to lay eggs in the flower
(c) Insect robbers consume pollens or nectar without
bringing about pollination
(d) Majority of the flowering plants produce homosexual
flowers
160 Refer to the given characteristics of some flowers :
I. Flowers are small. They are often packed in
inflorescence.
II. Flowers are colourless, nectarless and odourless
III. Well exposed stamens.
IV. Pollen grains produced in large number, light and
non-sticky.
V. Flowers often have a single ovule in each ovary.
VI. Stigma-large, often feathery.
The above features are the characteristics of
(a)
(b)
(c)
(d)
Self-pollination
Anemophily (pollination by wind)
Ornithophily (pollination by birds)
Entomophily (pollination by insects)
161 The events in pollen-pistil interaction are given
below.
I. Pollen grain germinates to form pollen tube.
II. Pollen tube enters the ovule through micropyle.
III. Pollen grain reaches the stigma.
IV. Pollen tube grows through the tissues of stigma and
style and reaches the ovary.
The sequential order of their occurrence is
(a) III → I → IV → II
(b) II → IV → III → I
(c) III → IV → II → I
(d) II → III → I → IV
162 Which of the following statement is correct?
(a) Pollination gives the guarantee of the promotion of
post-pollination events that lead to fertilisation
(b) The events ‘from pollen deposition on stigma until
pollen tubes enter the ovule’ are together referred to as
pollen-pistil interaction
(c) Pollen-pistil interaction is a dynamic process involving
pollen recognition followed by only promotion (not
rejection) of the pollen
(d) Pistil has no ability to recognise the pollen, whether
right or wrong type
35
163 Study the following and find correct statement(s).
I. Pollination by water is quite rare in flowering plants
and is limited to about 50 genera, mostly
monocotyledons.
II. Water is a regular mode of transport for the male
gametes among higher plant groups.
III. Distribution of bryophytes and pteridophytes are
limited because of the need of water for transport of
male gametes and fertilisation.
(a) Only I
(c) Only III
(b) II and III
(d) Only II
164 Read the following statements.
I. Double fertilisation was discovered by Nawaschin in
Lilium and Fritillaria.
II. The total number of nuclei involved in double
fertilisation is five.
III. The central cell of embryo sac, as a result of triple
fusion becomes primary endosperm cell (PEC).
IV. Synergids are haploid.
Choose the correct set of statements.
(a)
(b)
(c)
(d)
I, II and III
II and IV
I, III and IV
I, II, III and IV
165 Find out the correct statement(s).
I. Most common endosperm is of nuclear type.
II. Coconut water is male gametophyte.
III. Coconut has both free-nuclear and cellular type of
endosperm.
(a) I, II and III
(c) II and III
(b) I and III
(d) I and II
166 Find out the correct statement(s).
I. Endosperm formation is the prior event than embryo
formation.
II. Angiospermic and gymnospermic endosperm are 3n
and n , respectively.
III. Endospermic seeds are found in castor, barley and
coconut.
IV. In albuminous seed, food is stored in endosperm and in
non-albuminous seeds, it is strored in cotyledons.
(a) I and IV
(c) I and III
(b) II and III
(d) I, II, III and IV
167 Observe the following diagrams.
Seed
Achene
Endocarp
(A)
A. Fruit of apple
Mesocarp
(B)
B. Fruit of strawberry
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Select correct statement regarding the above fruits.
(a) Both are parthenocarpic fruits which develops without
fertilisation
(b) Both are true fruits which develops only from the ovary
(c) Both are false fruits in which thalamus also contributes
to fruit formation
(d) A is false fruit and B is true fruit
168 The given diagram is related to castor seeds. Select
the incorrect statement regarding the labelled parts.
Seed coat
Endosperm
Shoot apical
meristem
Cotyledon
Hypocotyl
Column II
A.
Antipodal
1.
3n
B.
Central cell
2.
2n
C.
MMC
3.
(n + n)
D.
Endosperm
4.
n
Codes
A
(a) 4
(c) 4
B
3
3
C
1
2
D
2
1
A
3
3
(b)
(d)
B
2
4
169 Match the following columns.
Column I
(Seeds / Fruits)
A.
Endospermic seed
1.
Wheat
B.
Non-endospermic seed
2.
Mango
C.
True fruit
3.
Cashew
D.
False fruit
4.
Pea
A
(b) 1
(d) 4
B
4
3
Codes
A
(a) 4
(c) 1
B
2
3
C
3
2
D
1
4
C
2
2
Column I
(Agents of pollination)
B.
Inner integuments
2.
Tegmen
A.
Wind
1.
Anemophily
C.
Ovary
3.
Fruit
B.
Water
2.
Hydrophily
D.
Ovules
4.
Seed
C.
Insects
3.
Entomophily
D.
Birds
4.
Ornithophily
D
4
4
A
(b) 3
(d) 4
Testa
Column II
(Technical term)
Outer integuments
C
2
3
B
4
3
170 Match the following columns.
Column I
(Ovary)
Column II
(Pistil)
C
1
2
D
3
1
173 Match the following columns.
Column II
B
3
2
D
2
1
Codes
A
(a) 1
(c) 4
B
2
2
C
3
3
D
4
1
(b)
(d)
A
1
2
B
3
3
C
2
4
D
4
1
174 Match the following columns.
Column I
(Parts of seed)
Column II
(Features)
A.
Monocarpellary
1. Free pistil
B.
Multicarpellary
2. Fused pistil
A. Cotyledon
1.
Portion below the cotyledon
C.
Syncarpous
3. Many pistil
B. Epicotyl
2.
Portion above the cotyledon
D.
Apocarpous
4. Single pistil
C. Plumule
3.
Stem tip
D. Hypocotyl
4.
Leaf of embryo
Codes
A
(a) 1
(b) 4
(c) 3
(d) 4
B
2
3
4
3
C
3
2
2
1
D
4
1
1
2
D
4
2
Column II
(Examples)
A.
Codes
A
(a) 1
(c) 1
C
1
1
172 Match the following columns.
III. Matching Type Questions
1.
Column I
Root tip
(a) Seed coat protect the seed from physical, temperature
or water damage
(b) Endosperm provides nourishment to the developing
embryo
(c) Castor seed has single cotyledon, i.e.
monocotyledonous and is albuminous
(d) Hypocotyl terminates at its lower end in the root tip
Column I
171 Match the following columns.
Codes
A
(a) 1
(c) 4
B
2
2
C
3
3
D
4
1
(b)
(d)
A
1
1
B
3
2
C
2
4
D
4
3
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
175 Match the following columns.
Column I
(Other modes of
reproduction)
Column II
(Examples)
A.
Parthenocarpy
1.
Grasses
B.
Apomixis
2.
Citrus
C.
Polyembryony
3.
Banana
Codes
A
(a) 1
(c) 3
37
Codes
A
(a) 2
(b) 1
(c) 3
(d) 4
B
3
2
2
3
C
4
3
4
2
D
1
4
1
1
177 Match the following columns.
Column I
B
2
2
C
3
1
A
(b) 2
(d) 3
B
1
1
C
3
2
176 Match the following columns.
Column I
Column II
A.
Viability of pollen
grains
1. Genetically different pollen
grains
B.
Autogamy
2. Prevailing temperature and
humidity
C.
Pollen allergy
3. Genetically similar pollen grains
D.
Xenogamy
4. Carrot grass
Column II
A.
Ovary
1.
Groundnut, mustard
B.
Ovule
2.
Guava, orange, mango
C.
Wall of fruit
3.
Pericarp
D.
Fleshy fruits
4.
Seed
E.
Dry fruits
5.
Fruit
Codes
A
(a) 5
(b) 1
(c) 1
(d) 5
B
4
2
3
4
C
3
3
2
1
D
2
4
4
2
E
1
5
5
3
NCERT & NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
NCERT
183 Which type of pollination occurs in self-incompatible
178 What is the correct sequence of development of
microsporogenesis?
(a) Pollen grain → Sporogenous tissue → Microspore
tetrad → PMC → Male gametes
(b) Sporogenous tissue → Microspore tetrad → PMC
→ Male gametes
(c) Pollen grain → Male gametes → PMC → Microspore
tetrad – Sporogenous tissue
(d) Sporogenous tissue → PMC → Microspore tetrad
→ Pollen grain → Male gametes
179 Strategies to prevent self-pollination are
(a) dioecy
(c) Both (a) and (b)
(b) self-incompatibility
(d) None of these
180 The portion of embryonal axis above the level of
cotyledons is
(a) epicotyl (b) hypocotyl
(c) plumule (d) radicle
181 Perisperm is
(a) residual nucellus
(c) covering of fruit
(b) residual endosperm
(d) None of these
182 Name the part of gynoecium that determines the
compatible nature of pollen grain.
(a) Pistil
(c) Ovum
(b) Ovary
(d) Ovule
plant?
(a) Self-pollination
(c) Water pollination
(b) Cross-pollination
(d) Wind pollination
NCERT Exemplar
184 In a typical complete, bisexual and hypogynous
flower the arrangement of floral whorls on the
thalamus from the outermost to the innermost is
(a) calyx, corolla, androecium and gynoecium
(b) calyx, corolla, gynoecium and androecium
(c) gynoecium, androecium, corolla and calyx
(d) androecium, gynoecium, corolla and calyx
185 Among the terms listed below, those that are not
technically correct names for a floral whorl are
I. androecium
II. carpel
III. corolla
IV. sepal
(a) I and IV
(c) II and IV
(b) III and IV
(d) I and II
186 Embryo sac is to ovule as ...... is to an anther.
(a) stamen
(b) filament
(c) pollen grain
(d) androecium
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187 A dicotyledonous plant bears flowers, but never
produces fruits and seeds. The most probable cause
for the above situation is
(a) plant is dioecious and bears only pistillate flowers
(b) plant is dioecious and bears both pistillate and staminate
flowers
(c) plant is monoecious
(d) plant is dioecious and bears only staminate flowers
188 During microsporogenesis, meiosis occurs in
(a) endothecium
(b) microspore mother cells
(c) microspore tetrads
(d) pollen grains
195 In an embryo sac, the cells that degenerate after
fertilisation are
(a) synergids and primary endosperm cell
(b) synergids and antipodals
(c) antipodals and primary endosperm cell
(d) egg and antipodals
196 While planning for an artificial hybridisation
programme involving dioecious plants, which of the
following steps would not be relevant?
(a) Bagging of female flower
(b) Dusting of pollen on stigma
(c) Emasculation
(d) Collection of pollen
189 From among the sets of terms given below, identify
197 In the embryos of a typical dicot and a grass, true
those that are associated with the gynoecium.
homologous structures are
(a) Stigma, ovule, embryo sac, placenta
(b) Thalamus, pistil, style, ovule
(c) Ovule, ovary, embryo sac, tapetum
(d) Ovule, stamen, ovary, embryo sac
(a) coleorhiza and coleoptile (b) coleoptile and scutellum
(c) cotyledons and scutellum (d) hypocotyl and radicle
190 Starting from the innermost part, the correct sequence
of parts in an ovule are
(a) egg, nucellus, embryo sac, integument
(b) egg, embryo sac, nucellus, integument
(c) embryo sac, nucellus, integument, egg
(d) egg, integument, embryo sac, nucellus
191 From the statements given below choose the option
that are true for a typical female gametophyte.
I. It is 8-nucleate and 7-celled at maturity.
II. It is free-nuclear during the development.
III. It is situated inside the integument, but outside the
nucellus.
IV. It has an egg apparatus situated at the chalazal end.
(a) I and IV
(c) I and II
(b) II and III
(d) II and IV
192 Autogamy can occur in a chasmogamous flower if
(a) pollen matures before maturity of ovule
(b) ovules mature before maturity of pollen
(c) Both pollen and ovules mature simultaneously
(d) Both anther and stigma are of equal lengths
193 Choose the correct statement from the following.
(a) Cleistogamous flowers always exhibit autogamy
(b) Chasmogamous flowers always exhibit geitonogamy
(c) Cleistogamous flowers exhibit both autogamy and
geitonogamy
(d) Chasmogamous flowers never exhibit autogamy
194 From among the situations given below, choose
the one that prevents both autogamy and geitonogamy.
(a) Monoecious plant bearing unisexual flowers
(b) Dioecious plant bearing only male or female flowers
(c) Monoecious plant with bisexual flowers
(d) Dioecious plant with bisexual flowers
198 The phenomenon observed in some plants where in
parts of the sexual apparatus is used for forming
embryos without fertilisation is called
(a) parthenocarpy
(b) apomixis
(c) vegetative propagation (d) sexual reproduction
199 In a flower, if the megaspore mother cell forms
megaspores without undergoing meiosis and if one of
the megaspores develops into an embryo sac, its
nuclei would be
(a) haploid
(b) diploid
(c) a few haploid and a few diploid
(d) with varying ploidy
200 The phenomenon wherein, the ovary develops into a
fruit without fertilisation is called
(a) parthenocarpy
(c) asexual reproduction
(b) apomixis
(d) sexual reproduction
201 In a fertilised embryo sac, the haploid, diploid and
triploid structures are
(a) synergid, zygote and primary endosperm nucleus
(b) synergid, antipodal and polar nuclei
(c) antipodal, synergid and primary endosperm nucleus
(d) synergid, polar nuclei and zygote
202 The outermost and innermost wall layers of
microsporangium in an anther are respectively.
(a) Endothecium and tapetum
(b) Epidermis and endodermis
(c) Epidermis and middle layer
(d) Epidermis and tapetum
203 A particular species of plant produces light,
non-sticky pollen in large numbers and its stigmas are
long and feathery. These modifications facilitate
pollination by
(a) insects
(b) water
(c) wind
(d) animals
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
Answers
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1 (c)
2 (a)
3 (d)
4 (c)
5 (b)
6 (d)
7 (d)
8 (d)
9 (a)
10 (a)
11 (d)
12 (d)
13 (c)
14 (d)
15 (b)
16 (b)
17 (b)
18 (c)
19 (a)
20 (a)
21 (c)
22 (d)
23 (d)
24 (c)
25 (c)
26 (d)
27 (b)
28 (a)
29 (a)
30 (c)
31 (a)
32 (b)
33 (b)
34 (d)
35 (c)
36 (a)
37 (a)
38 (c)
39 (a)
40 (a)
41 (c)
42 (c)
43 (a)
44 (c)
45 (c)
46 (c)
47 (b)
48 (c)
49 (b)
50 (c)
51 (d)
52 (c)
53 (d)
54 (c)
55 (d)
56 (a)
57 (c)
58 (c)
59 (c)
60 (c)
61 (a)
62 (a)
63 (b)
64 (c)
65 (a)
66 (c)
67 (a)
68 (a)
69 (b)
70 (b)
71 (d)
72 (b)
73 (c)
74 (b)
75 (b)
85 (b)
86 (c)
87 (c)
88 (d)
89 (a)
90 (b)
76 (d)
77 (a)
78 (b)
79 (b)
80 (b)
81 (b)
82 (a)
83 (d)
84 (b)
91 (a)
92 (b)
93 (d)
94 (d)
95 (c)
96 (c)
97 (c)
98 (b)
99 (b) 100 (b) 101 (b) 102 (c) 103 (d) 104 (a) 105 (d)
106 (d) 107 (c) 108 (c) 109 (c) 110 (b) 111 (a) 112 (c) 113 (d) 114 (c) 115 (a) 116 (b) 117 (d) 118 (c) 119 (a) 120 (a)
121 (a) 122 (c) 123 (d) 124 (d) 125 (a) 126 (a) 127 (c) 128 (d) 129 (d) 130 (a) 131 (c) 132 (d) 133 (b)
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134 (c) 135 (c) 136 (a) 137 (c) 138 (c) 139 (a) 140 (a) 141 (c) 142 (a) 143 (a) 144 (d) 145 (a) 146 (c) 147 (b) 148 (d)
149 (d) 150 (d) 151 (d) 152 (d) 153 (d) 154 (d) 155 (d) 156 (b) 157 (d) 158 (d) 159 (d) 160 (b) 161 (a) 162 (b) 163 (c)
164 (d) 165 (b) 166 (d) 167 (c) 168 (c) 169 (c) 170 (b) 171 (c) 172 (b) 173 (a) 174 (c) 175 (d) 176 (a) 177 (a)
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178 (d) 179 (c) 180 (a) 181 (a) 182 (a) 183 (b) 184 (a) 185 (c) 186 (c) 187 (d) 188 (b) 189 (a) 190 (b) 191 (c) 192 (c)
193 (a) 194 (b) 195 (b) 196 (c) 197 (c) 198 (b) 199 (b) 200 (a) 201 (a) 202 (d) 203 (c)
Answers & Explanations
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Stamen represents the male reproductive part of a
flower, whereas stigma, style and ovary, are the parts of
a carpel or pistil which represents the female
reproductive part of a flower.
(c) The terminal structure of stamen is called anther,
which contains pollen grains (male gametophyte).
Pollen grains are haploid in nature.
(b) The dehiscence (release of pollen grain) of anther
occurs through the line of dehiscence which is the
running groove on anther longitudinally. It separates the
theca of anther.
(d) A typical angiosperm anther is bilobed with each
lobe having two theca. The anther is a four-sided
(tetragonal) structure consisting of four microsporangia
located at the corner with two in each theca.
(d) Microsporangium develops further and becomes
pollen sac. It is like a sac in which pollen develops. It is
called pollen sac at the time of maturity.
(a) Sporogenous tissue occupies the centre of each
microsporangium. Each cell of this tissue is a potential
pollen mother cell and can give rise to microspore tetrad.
(d) Microsporangium is surrounded by four wall layers.
The outermost layer is epidermis which is followed by
endothecium, the middle layer and the innermost layer
called tapetum. The three outer layers of
microsporangium perform the function of protection
and help in dehiscence of anther to release pollen.
13 (c) Microspore mother cell and pollen mother cell are
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the same terms and form male gametes (pollens) by the
process called microsporogenesis.
(b) As the anthers of angiospermic mesophytic plants
mature and dehydrate, the line of dehiscence ruptures
releasing the microspores in atmosphere. These
microspores dissociate from each other and develop into
pollen grains.
(c) The inner layer of pollen grain is called intine. It is
a continuous and thin layer made up of cellulose and
pectin.
(c) Sporopollenin is the hardest substance in plant
kingdom. It is the major constituent of outer layer, exine
of pollen grains and is non-degradable.
(d) Sporopollenin enables in preservation of pollen as
fossils. Since, sporopollenin cannot be degraded by any
enzyme. It is not affected by high temperature, strong
acid or strong alkali. Thus, it keeps pollen grains
well-preserved as fossils.
(c) The germ pores are apertures in the exine layer of a
pollen grain which help in the initiation of pollen tube
and the release of the male gametes during fertilisation.
There are usually three germ pores in dicots (tricolpate)
and one in monocots (monocolpate).
(d) When a pollen grain is mature it contains two cells,
a vegetative cell and generative cell. The vegetative cell
is bigger, has abundant food reserve and a large
irregularly shaped nucleus. The generative cell is small
Answers & Explanations
2 (a) Stamen is the odd one out among the other options.
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and floats in the cytoplasm of the vegetative cell. It is
spindle-shaped with dense cytoplasm and a nucleus.
(b) The generative cell of a pollen grain divides to form
two male gametes in order to achieve the 3-celled stage
in angiospermic plants.
(a) 60% of angiosperms shed their pollens at 2-celled
stage and in rest 40%, the pollens are shed at 3-celled
stage.
(c) Pollen grains are rich in nutrients. These are
available in the market in the form of tablets and are
used as food supplements to improve health. Pollen
consumption has been claimed to enhance the
performance of athletes and race horses.
(a) Pollen grains can be stored for several years in
liquid nitrogen having a temperature of −196°C
(cryopreservation). Pollen grains can be later used in
plant breeding programmes.
(b) The part labelled as C shows ovary. It is the site of
fertilisation, the process in which the fusion of male and
female gametes takes place. Fertilisation occurs in the
ovary of a pistil.
(b) The diagram represents the multicarpellary,
syncarpous pistil of Papaver. The gynoecium of this
plant consists of more than one pistil, showing
multicarpellary condition. These pistils are fused
together and hence are called syncarpous.
(d) The diagram shows the multicarpellary apocarpous
pistil of Michelia. The gynoecium of this ovary consists
of more than one pistil (multicarpellary) which are free
(apocarpous).
(a) Ovule of an angiosperm is equivalent to the
megasporangium which consists of 2 synergids, 1 egg,
3 antipodal cells and a secondary nucleus.
(c) An ovule is an integumented megasporangium
found in angiosperms, which develops into seeds after
fertilisation.
(a) Chalazal pole is present just opposite to the
micropylar end and represents the basal part of the ovule.
(a) Integuments enclose a mass of cells called the
nucellus. Cells of the nucellus have abundant reserve
food materials.
(c) Embryo sac is also called the female gametophyte.
In flowering plants, it is formed by the division of the
haploid megaspore nucleus and acts as the site of
fertilisation and development of the embryo.
(a) Megaspore Mother Cell (MMC) is found in the
micropylar region of the nucellus. It is a large cell
containing dense cytoplasm and prominent nucleus.
(c) In most of the angiosperms, the megaspore mother
cell ( 2n ) divides meiotically (reductional division) to
produce 4 cells.
Out of these, three degenerate and the remaining one
forms the functional megaspore. This further divides
mitotically and forms embryo sac.
(c) Microsporogenesis and megasporogenesis are the
processes involving the formation of male gamete and
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female gamete, respectively by meiotic cell division in
flowering plants.
(c) In angiosperms, functional megaspore develops into
an embryo sac. The functional megaspore is the first
cell of the female gametophyte.
(b) The most common type of female gametophyte
(embryo sac) in angiosperms is the monosporic embryo
sac in which the embryo sac develops from a single
functional megaspore (n), while the other three
megasproes degenerate. The functional megaspore
undergoes three sequential mitotic divisions and gives
rise to the 8-nucleate and 7-celled mature embryo sac.
(c) The functional megaspore develops into the embryo
sac containing 2 synergids, l egg cell, 1 central cell and
3 antipodal cells. Thus, option (c) gives the correct
number of different cells in an embryo sac.
(d) The function of filiform apparatus is to guide the
entry of pollen tube into the synergids and release of
sperm cells.
(a) A typical angiospermic embryo sac at maturity has
8-nuclei. Six out of the eight nuclei are surrounded by
cell walls and organised into cells (egg apparatus and
antipodal cells) and the remaining two nuclei, called
polar nuclei, are situated below the egg apparatus in the
large central cell.
(c) Female gametophyte is 7-celled structure. Out of
these, three cells are grouped together at the
micropylar end and constitute of two synergids and
one egg cell, three antipodal cells are at the chalazal
end and the large central cell.
(b) Cleistogamous flowers are strictly autogamous
because they always remain close for ensuring
self-pollination. In these flowers, there is no chance of
cross-pollination.
66 (c) Cleistogamous flowers are not dependent on
pollinators. These are bisexual flowers which never
open, i.e. always remain closed. In such flowers, the
anthers and stigma lie very close to each other. When
anthers dehisce in the flower buds, pollen grains come
in contact with the stigma of the same flower,
i.e. autogamy occurs. So, these flowers produce assured
seed set, even in the absence of pollinators.
67 (a) Commelina has flowers which does not open at all,
i.e. cleistogamous flowers. So, even in the absence of
pollinating agent, assured seed setting takes place in
Commelina.
68 (a) Geitonogamy is a type of self-pollination. In other
words, geitonogamy is the transfer of pollen grains from
the anther of one flower to the stigma of another flower
of either the same or a genetically similar plant.
69 (b) Xenogamy is also called cross-pollination. In this,
transfer of pollen grains takes place between the anther
and the stigma of different plants of same species.
71 (d) Wind pollinated pollens are non-sticky and light so
that they can go far away in wind currents. These are
produced in large numbers, because there is a lot of
wastage of pollens.
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
condition, flowers occur on different plants, i.e. male
and female flowers are present on different plants.
Hence, it does not favour autogamy and geitonogamy
because autogamy takes place in bisexual flowers and
geitonogamy takes place between different flowers of
the same plant.
72 (b) Maize (corn cob) stigma are feathery and long,
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85 (b) Autogamy and geitonogamy both are prevented in
the papaya plant. This is because in papaya, male and
female flowers are present on different plants that is
each plant is either male or female (dioecy).
91 (a) The process of removal of anther from flower bud
before it dehisces is called as emasculation. When an
emasculated flower is covered with a bag of suitable
size to prevent contamination of its stigma with
unwanted pollen it is called bagging. These methods are
a part of artificial hybridisation technique used in
plants.
93 (d) Double fertilisation is the fusion of two male
gametes to two different cells of the same female
gametophyte.
It consists of the following two events
l
l
Syngamy is the fusion of the egg nucleus with one
male gamete.
Triple fusion is the fusion of second male gamete and
polar nuclei of central cell.
95 (c) Out of the given structures, antipodal cell, egg cell,
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synergid cell and male gamete are haploid. Thus, option
(c) is correct. The ploidy of the remaining structures
mentioned is diploid.
(c) Out of the male gametes discharged in the synergid,
one fuses with the egg and other fuses with central cell
nuclei. The fusion between male gamete and egg is
called syngamy or true fertilisation which forms zygote
(2n). The fusion between male gamete and central cell
nuclei is called triple fusion and it results in the
formation of a triploid primary endosperm nucleus (3n).
(b) Two polar nuclei and one nuclei of the remaining
male gamete (total 3 nuclei) are involved in the triple
fusion of double fertilisation.
(c) Option (c) is correct. If stem has 2n = 10 number of
chromosomes, then
Endosperm = 3n = 5 × 3 = 15 chromosomes.
Egg cell = 1n = 1 × 5 = 5 chromosomes.
Polar nuclei = 2n = 2 × 5 = 10 chromosomes.
(d) Option (d) is correct. The ploidy of endosperm is 3n.
Now, Chromosome given = 36
36
Haploid number =
= 12
3
Chromosomes of male and female gametes are haploid,
so answer is 12 and 12, respectively.
(a) After triple fusion, i.e. the fusion of male gametes
and polar nuclei, the central cell of female gametophyte
becomes the Primary Endosperm Cell (PEC).
(d) Option (d) is correct. If a male plant is diploid ( 2n )
it will produce haploid male gamete (n ).
Answers & Explanations
73
which wave in the air to trap pollen grains.
(c) The flowers with packed inflorescence and single
ovary are wind pollinated. These flowers produce pollen
grains in large numbers and such pollen grains are light
weighted sometimes winged, e.g. cereals and grasses.
(b) Insect or Wind act as pollinating agents in the
majority of aquatic plants such as water hyacinth and
water lily. In these plants, the flowers emerge above the
level of water and are pollinated by insects or wind as in
most of the land plants.
(d) Vallisneria is a water pollinated plant. In
Vallisneria, the female flowers reach the surface of
water by the long stalk and the male flowers or pollen
grains are released on to the surface of water. These are
carried passively by water currents to the female
flowers at the surface of water.
(b) Wind pollinated and water pollinated flowers are
non-colourful. As these do not need any biotic agency
for pollination, there is no need for fragrance, nectar
and colourfulness.
(b) Pollenkitt is present in entomophily. It is a yellow,
sticky, viscous and oily layer that covers exine of some
insect pollinated pollen grains. Its major function is to
make the pollen to stick to the bugs. Thus, it helps in
pollination.
(b) Attractants and rewards are required for entomophily
(insect pollination). Flowers are colourful and produce a
specific odour to attract the insects for effective
pollination. To sustain animal visits, flowers also provide
nectar and pollen grains as rewards to them.
(b) Out of the given options, only Yucca gloriosa has
developed an obligate symbiotic relationship with the
moth, Pronuba yuccasella. The moth cannot complete
its life cycle without the association with Yucca flowers.
The moth deposits its eggs in the locule of the ovary
and the flower in turn gets pollinated by the moth. The
larvae of the moth come out of the eggs as the seeds
start developing.
(a) Continued self-pollination results in inbreeding
depression. Due to the continuous breeding of related
species the productivity of the progeny species is
reduced which leads to inbreeding depression.
(d) Both option (a) and (b) are correct as
Flowering plants have developed many devices to
discourage self-pollination. In some species, pollen
release and stigma receptivity is non-synchronised, i.e.
either the pollen is released before the stigma becomes
receptive or stigma becomes receptive much before the
release of pollen.
In other species, the anther and stigma are placed at
different positions, so that the pollen cannot come in
contact with the stigma of the same flower.
Both these devices prevent autogamy (self-pollination)
and increases cross-pollination.
(b) Dioecious flowering plants prevent the occurrence
both autogamy and geitonogamy in them. In dioecious
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If a female plant is tetraploid ( 4n ) it will produce
tetraploid polar nuclei ( 4n ).
Endosperm is formed by fusion of male gamete with
polar nuclei, i.e. fusion of tetraploid polar nuclei and
haploid male gamete will give pentaploid (5n )
endosperm.
(d) Pollen tube liberates both male gametes in
synergids, out of which one male gamete fuses with egg
cell and other with the polar nuclei.
(c) Endospermogenesis and embryogenesis are the
post-fertilisation event under which formation of
endosperm and embryo take place. Whereas,
megasporogenesis is the formation of megaspores and is
a pre-fertilisation event.
(a) Endosperm is consumed by the developing embryo
in seeds of pea plant. Endosperm may either be
completely consumed by the developing embryo in
plants like pea, groundnut, beans before seed maturation
or it may persist in mature seed in plants like castor,
maize and coconut and be used up during seed
germination.
(c) In wheat or maize (family–Poaceae), the scutellum
is thought to be a large, shield-shaped cotyledon or seed
leaf, which is situated towards one side (lateral) of the
embryonal axis.
(a) Persistent nucellus in the seed is known as
perisperm. The albuminous seeds usually retain a part of
endosperm as it is not completely used up during
embryo development. But in some seeds, remnants of
nucellus are also persistent. This residual persistens
nucellus is called perisperm, e.g. in black pepper and
beet root.
(a) Dehydration and dormancy are most crucial for seed
storage. In dehydration, there is less amount of water
due to which the seed enzymes cannot work and hence,
there will be no germination. Dormancy is the time
period in which seed cannot grow due to inactive state
of embryo or lacking of other necessary condition for
growing.
(d) Thalamus contributes to fruit formation in apple,
strawberry and cashewnut. In such plant species where
the thalamus contributes to fruit formation, the fruits are
called false fruits. But in most of the plants, the fruit
develops from the ovary (true fruits) and other floral
part degenerates and fall off.
(a) The oldest viable seed is that of a lupine, Lupinus
arcticus excavated from Arctic Tundra. The seed
germinated and flowered after an estimated record of
10,000 years of dormancy.
(c) Apomixis is a special mechanism found in flowering
plants to produce seeds without meiosis and fertilisation.
It is a type of asexual reproduction which mimics sexual
reproduction and is commonly found in species of
Asteraceae and grasses.
(d) In varieties of both Citrus and mango ovules contain
many embryos. In these varieties some of the nucellar
cell surrounding the embryo sac starts dividing, protrude
into the embryo sac and develop into many embryos.
130 (a) Occurrence of more than one embryo is called
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polyembryony. It is generally observed in Citrus
varieties. Orange and lemon are common examples of
polyembryony.
(c) Option (c) is correct as
In asexual/vegetative and apomictic reproduction,
mitotic cell divison takes place, due to which the
resultant progeny are identical to the parents and to
each other (clone nature of offspring).
(d) Nucellar polyembryony is a form of seed
production that occurs in Citrus varieties. During the
development of seeds in plants that possess this genetic
trait, the nucellar tissue which surrounds the
megagmetophyte can produce additional embryos
(polyembryony) which are genetically identical to the
parent plant. These nucellar seedling are clones of the
parent.
(b) Synergids, antipodal cell, haploid egg do not take
part in seed or apomictic seed formation because they
are haploid and can only take part in sexual
reproduction. Only maternal sporophytic tissue in ovule
takes part in seed formation in apomictic
embryogenesis as it is diploid.
(c) Assertion is true, but Reason is false and can be
corrected as
The gynoecium represents the female reproductive part
of the flower and consists of pistil.
(c) Assertion is true, but Reason is false and can be
corrected as
In meiosis, the resultant cells do not have exactly same
genetic makeup due to the process of crossing over.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
The structures related to sexual reproduction in
flowering plants are flowers. This is because
embryological processes during sexual reproduction
occur in ovary, which is a part of a flower.
(c) Assertion is true, but Reason is false and can be
corrected as
Megaspore mother cell is diploid and megaspore is
haploid.
(c) Assertion is true, but Reason is false and can be
corrected as
Pollen grain does not contain the stigma, style and
ovary. These are parts of the female reproductive
structure of flower, gynoecium.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Geitonogamy is functionally cross-pollination involving
a pollinating agent, but genetically it is similar to
autogamy. This is because the pollen grains come from
different flowers of the same plant.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Cleistogamous flowers do not open at all. This ensures
fertilisation and consequently leads to the production of
assured of seed-set even in the absence of pollinators.
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CHAPTER 02 > Sexual Reproduction in Flowering Plants
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corrected as
Removal of anthers (emasculation) is done in artificial
hybridisation as it prevents contamination of the pistil
(female reproductive structure).
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Endosperm is source of nutrition for the developing
embryo, thus the development of endosperm takes
place before the process of embryogenesis.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
In non-albuminous seeds, the endosperm is fully
consumed by the developing embryo and thus, no
residue is left in such seeds.
(d) Assertion is false, but Reason is true. Assertion
can be corrected as
Mango is a true fruit, which develops only from the
ovary.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Parthenocarpic fruits are either seedless or contain
non-viable seeds. This is because such fruits are
formed without fertilisation.
(c) Assertion is true, but Reason is false and can be
corrected as
Apomixis is the type of asexual reproduction in which
seeds are produced without meiosis (reductional
division) and syngamy.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion. The correct
explanation is as follows
Parthenocarpy involves the formation of seedless
fruits, because the fruit formation from parthenocarpy
does not involve pollination and fertilisation and
hence, fruits develop without seed formation.
Apomixis is a mechanism that mimics sexual
reproduction and produces seeds without the union of
male and female gametes. The diploid egg cell is
formed without meiotic division and develops into
embryo without fertilisation, e.g. members of
Asteraceae and grasses.
(d) Assertion is false, but Reason is true. Assertion
can be corrected as
In apomixis, sexual reproduction is completely
replaced by asexual reproduction. In this process, no
new genetic sequence is formed as the progeny is
genetically identical to the parent.
(d) The statement in option (d) is correct. Rest of the
statements are incorrect and can be corrected as
l
l
l
The inner wall of pollen grain is called intine.
Sporogenous tissue is diploid and undergoes meiotic
division to form microspore tetrads.
Endothecium is the wall around the microsporangium,
which provides protection and helps in the dehiscence
of anther to release the pollen.
151 (d) Statements I, II and IV are correct. Statement III is
incorrect and can be corrected as
Self-incompatibility is a device which ensures
cross-pollination, prevents self-fertilisation and keeps
genetic control for self-fertilisation.
153 (d) Statements III and IV are correct. Statements I and II
are incorrect and can be corrected as
l
l
In a mature pollen grain vegetative cell is bigger and has
abundant food reserve and a large irregular shaped
nucleus.
The generative cell is small and floats in the cytoplasm
of vegetative cell. It is spindle-shaped with dense
cytoplasm and nucleus.
156 (b) Statement I is true, but statement II is false. The false
statement can be corrected as
Pollination by ants is called myrmecophily.
157 (d) The statement in option (d) is incorrect and can be
corrected as
l
l
Ornithophily is pollination by birds and occurs in Butea,
Bignonia, etc.
In Adansonia, chiropterophily occurs (i.e. pollination
by bats).
Rest of the statements are correct.
159 (d) The statement in option (d) is incorrect and can be
corrected as
Majority of the flowering plants produce bisexual
flowers.
Rest of the statements are correct.
162 (b) The statement in option (b) is correct.
Rest of the statements are incorrect and can be corrected
as
l
l
l
Pollination does not give the guarantee of the promotion
of post-pollination events that lead to fertilisation.
Pollen-pistil interaction is a dynamic process involving
pollen recognition followed by promotion or inhibition
of the pollen.
The pistil has the ability to recognise the pollen, whether
it is of the right type (compatible) or of the wrong type
(in compatible).
163 (c) Statement III is correct. Statements I and II are
incorrect and can be corrected as
l
l
Pollination by water is quite rare in flowering plants and
is limited to about 30 genera, mostly monocotyledons.
Water is a regular mode of transport for the male
gametes among lower plant groups such as algae and
bryophytes.
165 (b) Statements I and III are correct, but statement II is
incorrect and can be corrected as
The coconut water from tender coconut represents
free-nuclear endosperm not male gametophyte and the
surrounding white kernel is the cellular endosperm.
167 (c) The statement in option (c) is correct. Rest of the
statements are incorrect and can be corrected as
Answers & Explanations
141 (c) Assertion is true, but Reason is false and it can be
43
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44
168
178
179
180
181
182
Answers & Explanations
184
185
186
187
The fruit of apple (A) and fruit of strawberry (B), are
false fruits, in which thalamus also contributes to fruit
formation alongside ovary. These fruits are not
parthenocarpic because parthenocarpic fruits are
seedless and are formed without fertilisation.
(c) The statement in option (c) is incorrect and can be
corrected as
Castor seed is dicotyledonous, i.e. with two cotyledons
and is albuminous, i.e. having residual endosperm.
Rest of the statements are correct.
(d) The correct sequence is given in option (d).
During microsporogenesis, the sporogenous tissue
initially forms Pollen Mother Cell (PMC). Then this
pollen mother cell undergoes meiotic division to form
microspore tetrad. The microspores further develop into
pollen grains, which contain the male gametes.
(c) Dioecy and self-incompatibility are the methods to
prevent self-pollination in plants. In dioecy, male and
female flowers are borne on separate plants. So, that
cross-pollination is promoted.
In self- incompatibility, pollens are prevented to fertilise
the ovules of same flower by inhibiting pollen
germination on the pistil.
(a) A typical dicotyledonous embryo consists of an
embryonal axis and two cotyledons. The portion of
embryonal axis above the level of cotyledon is the
epicotyl and below the level of cotyledon is hypocotyl.
(a) In some plants/seeds, such as black pepper remains
of nucellus are also persistent, this is called as
perisperm.
(a) The pistil is the part of gynoecium which has the
ability to recognise the pollen. Thus, determine the
compatible nature of pollen grain.
(a) In a typical complete, bisexual and hypogynous
flower, the arrangement of floral whorls on the
thalamus from the outermost to the innermost is
Calyx is the whorl of sepals is the outermost.
Corolla is the whorl of petals inside the calyx.
Androecium is the whorl of stamens inside the corolla.
Gynoecium is the whorl of pistils in the centre of the
flower forming the innermost whorl.
(c) Sepal and carpel are technically incorrect names for
a whorl. This is because sepals collectively form a
whorl called as calyx, while the carpel is technically
known as gynoecium.
(c) The pollen grains represent the male gametophyte.
As the anther matures and dehydrates, the microspore
dissociates from each other and develop into pollen
grains. So, embryo sac is to ovule as pollen grains is to
an anther.
(d) In dioecious plants, the unisexual flower is either
staminate, i.e. bearing stamens only or is pistillate
bearing only pistil or carpel. For the production of fruits
and seeds fertilisation must take place, which is possible
only in the presence of both male and female flowers.
So, in this situation plant is dioecious and bears only
staminate flowers.
188 (b) During microsporogenesis, meiosis occurs in
Microspore Mother Cell (MMC) and four haploid
microspores (microspore tetrad) are formed.
189 (a) Gynoecium is the female reproductive part of a
flower and is also called pistil. Each pistil has three
parts, i.e. stigma, style and ovary. Inside the ovarian
cavity, the placenta is located. Arising from placenta is
the ovule. The functional megaspore undergoing the
meiotic division develops into embryo sac. Thus, option
(a) is correct.
190 (b) Starting from the inner to the outer side of ovule,
the ovule bears egg cell, embryo sac, nucellus, and
integument.
191 (c) Statements I and II are correct. Statements III and
IV are incorrect and can be corrected as
l
l
Female gametophyte is present inside the nucellus.
Egg apparatus is situated at the micropylar end.
192 (c) Autogamy is self-pollination. In chasmogamous
193
194
195
196
197
199
202
203
flower, anthers and stigma are exposed. For autogamy
in such a flower to take place, pollen and ovule should
mature simultaneously and anther and stigma should lie
close to each other.
(a) The statement in option (a) is correct as
Cleistogamous flowers (that do not open at all) always
exhibit autogamy.
Rest of the statements are incorrect and can be corrected
as
Chasmogamous flowers (with exposed anther and
stigma) can exhibit autogamy, geitonogamy or
xenogamy.
(b) Dioecious plants (bearing only male or female
flowers) prevent both autogamy and geitonogamy.
(b) In a fertilised embryo sac, antipodals and synergids
gradually degenerate after the formation of zygote.
(c) If the female parent produces unisexual (dioecious)
flowers, there is no need for emasculation. Because in a
dioecious flower only single reproductive structure is
present thus chances of self-pollination are not there.
(c) In the embryos of a typical dicot and a grass
(monocot), true homologous structures are cotyledons
and scutellum. This is because in the monocots such as
the grass family a single cotyledon is present which is
called scutellum.
(b) Option (b) is correct.
Megaspore mother cell is diploid (2n). lf it forms
megaspores without meiosis, the megaspores will be
diploid (2n) too. If this diploid megaspore develops into
embryo sac, its nuclei would also be diploid.
(d) A typical microsporangium is generally surrounded
by four-wall layers, i.e. the epidermis (outermost
protective layer), then endothecium, then middle fibrous
layers and the tapetum (innermost nutritive layer).
(c) Wind pollination requires light and non-sticky
pollen grains so that, they can be transported with wind
currents and its stigma are long and feathery to easily
trap airborne pollen grains.
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CHAPTER > 03
Human
Reproduction
NEET
Å
KEY NOTES
Humans are sexually reproducing and viviparous (i.e. give
birth to young ones) organisms, having distinct male and
female sexes.
Å
The testes are situated outside the abdominal cavity within a
pouch called scrotum. The scrotum helps in maintaining the
low temperature of the testes (2-2.5°C lower than the normal
internal body temperature) necessary for the production of
sperms (spermatogenesis).
Male Reproductive System
Å
The male reproductive system is located in the pelvis region.
Å
Å
It includes a pair of testes, accessory ducts, glands and the
external genitalia (penis).
In adults, each testis is oval in shape, with a length of about
4-5 cm and width of about 2-3 cm.
Å
Each testis has about 250 compartments called testicular
lobules and each lobule contains one to three highly coiled
seminiferous tubules.
Å
Seminiferous tubules are lined inside by two types of
cells, i.e. male germ cells (spermatogonia), undergo
meiotic divisions leading to sperm formation and Sertoli
cells, provide nutrition to the dividing germ cells. Region
outside the seminiferous tubules has Leydig cells or
interstitial cells, which secrete testicular hormones called
androgens.
Å
The male sex accessory ducts include rete testis, vasa
efferentia, epididymis and vas deferens. These ducts store
and transport the sperms from the testis to the outside
through urethra. The urethra originates from urinary bladder
and extends through the penis to its external opening, i.e.
urethral meatus.
Ureter
Seminal vesicle
Urinary bladder
Vas deferens
Prostate gland
Penis
Urethra
Glans penis
Foreskin
Ejaculatory duct
Rectum
Anus
Bulbourethral gland
Testis
Scrotum
Diagrammatic sectional view of male pelvis showing reproductive
system
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Å
The penis is the highly vascularised external copulatory
organ in males. The enlarged end of penis called the glans
penis, covered by a loose fold of skin called foreskin.
Ureter
Å
Å
Urinary
bladder
Vas deferens
Seminal
vesicle
Prostate gland
Bulbourethral
gland
The oviducts (Fallopian tube), uterus and vagina
constitute the female accessory ducts.
Each Fallopian tube is about 10-12 cm long and extends
from the periphery of each ovary to the uterus, the part
closer to the ovary is the funnel-shaped infundibulum. The
edges of the infundibulum possess finger-like projections
called fimbriae, which help in collection of the ovum after
ovulation. The infundibulum leads to a wider part of the
oviduct called ampulla. The last part of the oviduct,
isthmus has a narrow lumen and it joins the uterus.
Uterine fundus
Epididymis
Uterine cavity
Urethra
Vasa efferentia
Rete testis
Testicular
lobules
Isthmus
Fallopian
Ampulla
tube
Infundibulum
Testis
Glans penis
Foreskin
Diagrammatic view of male reproductive system (part of testis is
open to show inner details)
Å
The male accessory glands include paired seminal
vesicles, a prostate and paired bulbourethral glands.
Secretions of these glands constitute the seminal plasma
which is rich in fructose, calcium and certain enzymes.
This secretion along with the sperm forms semen.
Female Reproductive System
Å
It includes a pair of ovaries, pair of Fallopian tubes
(oviducts), uterus, cervix, vagina and external genitalia
and a pair of mammary glands.
Endometrium
Myometrium
Perimetrium
Ovary
Fimbriae
Cervix
Cervical canal
Vagina
Diagrammatic sectional view of the female reproductive system
Å
Uterus (womb) opens into vagina through a narrow
cervix. The cavity of the cervix is called cervical canal
which forms the birth canal along with the vagina.
Å
The uterus has three layers of tissue, i.e. the external thin
membranous perimetrium, middle thick layer of smooth
muscle, myometrium and inner glandular layer called
endometrium.
The female external genitalia include
Mons pubis A cushion of fatty tissue covered by skin
and pubic hair.
Labia majora Fat padded skin folds, extend from mons
pubis and surround the vaginal opening.
Labia minora A pair of inner folds of tissue under labia
majora.
Hymen The membrane that partially covers the vaginal
opening.
Clitoris A tiny finger-like structure, lying at the upper
junction of two labia minora above the urethral
opening, is sensitive to stimulation.
In females, the mammary glands are one of the secondary
sexual characteristics. These are paired structures that
contain glandular tissue and variable amount of fat.
Glandular tissue is divided into 15-20 mammary lobes,
having clusters of cells called alveoli.
The mammary alveolus secretes milk and stores in its
lumen. These alveoli open into mammary tubules, which
join to form mammary duct. The numerous mammary
ducts connect to form wider ampulla which connects to
lactiferous duct from which milk is sucked out.
Å
n
Cervix
Uterus
Urinary bladder
Pubic symphysis
Urethra
Clitoris
Labium minora
Labium majora
n
Rectum
n
Vagina
n
Anus
n
Vaginal orifice
Diagrammatic sectional view of female
pelvis showing reproductive system
Å
Å
Ovaries are the primary female sex organ that produce
ova and ovarian hormones.
The ovaries are located one on each side of the lower
abdomen. Each ovary is about 2-4 cm in length and is
connected to the pelvic wall and uterus by ligaments. Each
ovary is covered by a thin epithelium which encloses the
ovarian stroma. The stroma is divided into two zones, i.e.
a peripheral cortex and an inner medulla.
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Å
Å
Å
KEY NOTES
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CHAPTER 03 > Human Reproduction
Gametogenesis
Å
It is the process by which the primary sex organs, the testis
in the males and the ovaries in the females produce gametes,
i.e. sperms and ovum.
Å
The increased level of GnRH acts at the anterior
pituitary and stimulates Luteinizing Hormone (LH) and
Follicle Stimulating Hormone (FSH).
Å
LH acts on the Leydig cells and stimulates synthesis and
secretion of androgens, which in turn stimulate the
process of spermatogenesis.
Å
FSH acts on the Sertoli cells and stimulates secretion of
some factors which help in the process of
spermiogenesis.
Å
A normal human sperm structure is composed of a
head, neck, a middle piece and a tail.
Å
Head contains anterior small acrosome, which is filled
with enzymes and help in the fertilisation of the ovum.
Å
Middle piece possesses numerous mitochondria, which
produce energy for the movement of tail that facilitates
sperm motility essential for fertilisation.
Spermatogenesis
Å
It is a process of formation of sperm through meiotic division
and later some structural modifications from germ cells
present in testes in males.
n
n
n
n
n
n
The germ cells called spermatogonia are present on the
inside wall of the seminiferous tubules.
These cells are diploid and increase in number through
mitosis.
Some of the spermatogonia, primary spermatocytes,
undergo meiosis, forming two equal cells called
secondary spermatocytes. They are haploid (with 23
chromosomes but are still duplicate).
Each of the two secondary spermatocytes undergoes
second cell division (to separate the duplicate
chromosomes) producing four haploid spermatids.
Each has only one set of 23 (unpaired, unduplicated)
chromosomes.
Oogenesis
Å
It is the process of formation of female gametes (oocyte)
through meiotic division of germ cells, present in the
ovary in females.
n
Spermatids transform into spermatozoa (sperm cells) by
developing a head, neck, middle piece and a tail. This
process is called spermiogenesis.
n
Sperm heads become embedded in the Sertoli cells that
provide nourishment and molecular signals.
n
n
Final release of sperms (spermiation) from seminiferous
tubules is under the influence of hormonal and
physiological signals.
n
Å
Spermatogenesis includes three phases as indicated in the
following figure
Spermatogonia
Mitosis and
differentiation
At puberty
Chromosomes
number per cell
(46)
n
n
Primary spermatocytes
1st meiotic
division
Secondary spermatocytes
n
(23)
2nd meiotic
division
(23)
n
Spermatids
Differentiation
Spermatozoa
n
Diagrammatic view of phases in spermatogenesis
Å
It starts at the age of puberty due to significant increase in
the secretion of Gonadotropin Releasing Hormone (GnRH).
Å
It is initiated during the embryonic development
stage when two million gamete mother cells
(oogonia) are formed in each foetal ovary.
Oogonia start meiotic division which gets arrested at
prophase-I stage. They are referred to as primary
oocytes.
Each oocyte gets surrounded by the layers of
granulosa cells that nourish it. Oocyte along with the
cell layers around, is called primary follicle.
More layers of granulosa cells and another theca
layer surround it and now it is called secondary
follicle.
Secondary follicle transforms into tertiary follicle
that has a fluid-filled cavity called antrum.
The primary oocyte within the tertiary follicle grows
in size and completes its first meiotic division now.
This is an unequal division that results in the
formation of a large haploid cell called secondary
oocyte and a tiny cell called first polar body.
Secondary oocyte keeps nearly all the nutrient rich
cytoplasm, leaving only a haploid nucleus to the
polar body.
The tertiary follicle undergoes certain changes to
mature into Graafian follicle. The oocyte gets
glycoprotein deposits that form a non-cellular
coating called zona pellucida, around it.
The Graafian follicle ruptures to release secondary
oocyte (ovum) from the ovary.
The release of haploid secondary oocyte from the ovary,
under the influence of LH surge, is called ovulation.
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48
Å
The first menstruation starts at puberty and is called
menarche, while its stoppage around 50 years of age is
called menopause.
Å
The menstruation and the related events are repeated
every 28-29 days (in normal females) in a cyclical fashion,
that is why it is called menstrual cycle.
Å
Changes in the levels of pituitary and ovarian hormones
bring about the cyclical changes in the ovary and uterus
during menstrual cycle. It takes place in ovaries.
Chromosome number
per cell
46
Foetal life
23
23
Birth
childhood
Puberty
Fertilisation and Implantation
Å
A sperm during fertilisation comes in contact with the
zona pellucida of the ovum and induces changes in the
membrane, which blocks the entry of the other sperms.
Thus, ensuring that only one sperm can fertilise an ovum,
i.e. prevents polyspermy.
Å
The secretions of the acrosome help the sperm to enter into
the cytoplasm of the ovum through zona pellucida and the
plasma membrane. Corona radiata is the innermost layer
of ovum. It is dissolved by corona-penetrating enzymes of
acrosome.
Å
This induces the completion of meiotic division of the
secondary oocyte. The secondary meiotic division results
in the formation of a secondary polar body and a haploid
ovum.
Å
The haploid nucleus of the sperm and that of ovum fuse
together to form a diploid zygote.
Å
Sex of the baby is decided at this stage. After fusion of the
male and female gametes, the zygote would carry either
XX or XY depending on whether the sperm carrying X or Y
fertilised the ovum. The zygote carrying XX would
develop into a female baby and XY would form a male
baby.
Å
The mitotic division starts as the zygote (fertilised ovum)
moves through the isthmus of the oviduct towards the
uterus, forming 2, 4, 8, 16 daughter cells called
blastomeres. This process is called cleavage.
Å
During cleavage, the young embryo slowly moves down
the Fallopian tube towards the uterus and events taking
place are during this route are as follows
Oogonia
Mitosis and
differentiation
Primary oocyte
Ist meiotic
division
(completed
prior to
ovulation)
Secondary oocyte
First
Adult
polar body
reproductive
life
Second
Ovum
polar body
Diagrammatic view of phases in oogenesis
Menstrual Cycle
Å
The reproductive cycle in female primates is called
menstrual cycle.
Å
The major events of menstrual cycle are
n
n
n
n
Å
Å
Menstrual (bleeding) phase lasts for about 3-5 days.
The endometrium lining of uterus breaks down due to
the deficiency of progesterone. Blood vessels rupture,
causing bleeding through vagina.
Follicular (proliferative) phase lasts for about
14 days. The endometrium rebuilds, FSH and LH
secretions increase that stimulate follicular
development as well as secretion of oestrogen.
Ovulatory phase occurs at about 14th day. Both LH
and FSH attain a peak level. Maximum level of LH
(LH surge) ruptures the Graafian follicle and thereby,
release the ovum.
Luteal (secretory) phase lasts for about 10 days. The
remaining part of Graafian follicle transforms into
corpus luteum, which secretes progesterone for the
maintenance of endometrium.
After menstruation, the process of ovulation will occur
again and the same process follows in a time period of
28-29 days.
Cyclic menstruation indicates the normal reproductive
phase and it continues from menarche to menopause.
NEET
n
n
n
n
n
The embryo with 8-16 blastomeres is called morula.
But, it is not larger than a zygote.
The morula continues to divide and transforms into
blastocyst, as it moves further into the uterus. This
process of transformation is called blastulation.
The blastomeres in the blastocyst are arranged into an
outer layer called trophoblast and the inner group of
cells attached to trophoblast called the inner cell
mass.
The trophoblast layer then gets attached to the
endometrium and the inner cell mass differentiates into
the embryo. After attachment, the uterine cells divide
rapidly and cover the blastocyst.
As a result, the blastocyst becomes embedded in the
endometrium of the uterus. This is called implantation
and it leads to pregnancy (i.e. the time from conception
to birth).
KEY NOTES
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CHAPTER 03 > Human Reproduction
Pregnancy and Embryonic
Development
Å
Å
Å
After implantation, finger-like projections appear on the
trophoblast called chorionic villi, which are surrounded by
the uterine tissue and maternal blood.
The chorionic villi and the uterine tissue become
inter-digitated with each other and jointly form a structural
and functional unit between foetus and maternal body called
placenta.
The placenta performs the following functions
It facilitates the supply of oxygen and nutrients to the
embryo.
Å
In humans, pregnancy lasts for 9 months and foetal
heart is formed after one month of pregnancy.
Å
The first sign of growing foetus may be noticed by
listening to the heart sound carefully through
stethoscope.
Å
By the end of second month, the foetus develops limbs
and digits. By the end of 12 weeks, major organ
systems and external genitalia are well-developed.
Å
The first movement of the foetus and appearance of
hair can be observed during the fifth month.
Å
By the end of 24 weeks (second trimester), the body is
covered with fine hair, eyelids get separated and
eyelashes are formed.
Å
By the end of nine months of pregnancy, the foetus
becomes fully developed and is ready for delivery.
n
n
n
n
n
Å
Å
It aids in the removal of carbon dioxide and waste
materials produced by the foetus.
The placenta is connected to the embryo through the
umbilical cord, which helps in the transport of substances
to and from the embryo.
Placenta also acts as an endocrine tissue and produces
several hormones like human Chorionic Gonadotropin
(hCG), human Placental Lactogen (hPL), oestrogen,
progestogens, etc.
In the later phase of pregnancy, hormone called relaxin is
also secreted by the ovary. It is important to note that
hCG, hPL and relaxin are produced in women only
during pregnancy.
Parturition and Lactation
Å
The time period during which the embryo remains in
the uterus is called gestation period. It is about 9
months in humans.
Å
Vigorous contraction of the uterus at the end of
pregnancy causes expulsion/delivery of the foetus.
This process of delivery of the foetus (childbirth) is
called parturition. It is induced by a complex
neuroendocrine mechanism.
Å
The signals of parturition originate from the fully
developed foetus and the placenta, which induce mild
uterine contractions called foetal-ejection reflex.
Immediately after implantation, the inner cell mass
differentiates into three germ layers, i.e. ectoderm (outer
layer), endoderm (inner layer) and mesoderm (develop
between ectoderm and endoderm).
n
These three layers give rise to all tissues (organs) in adults.
Inner cell mass contains stem cells which have the potency to
give rise to all the tissues and organs.
n
End Products of Embryonic Germ Layers
Ectoderm
Mesoderm
Endoderm
Epidermis
Dermis
Lining of the digestive
system
Hair, nails, sweat glands
All muscles of the
body
Lining of the respiratory
system
Brain and spinal cord
Cartilage
Urethra and urinary bladder
Cranial and spinal nerves
Bone
Gall bladder
Retina, lens and cornea
of eye
Blood
Liver and pancreas
Inner ear
All other
connective tissues
Thyroid gland
Epithelium of nose,
mouth and anus
Blood vessels
Parathyroid gland
Enamel of teeth
Reproductive
organs and kidneys
Thymus
n
This triggers the release of oxytocin from the
maternal pituitary. It promotes contractions of
uterine muscles, which in turn stimulate further
secretion of oxytocin.
The stimulatory reflex between the uterine
contraction and oxytocin secretion continues
resulting in stronger contractions. This leads to the
expulsion of the baby out of the uterus through the
birth canal.
Soon after the birth of baby, placenta is also expelled
out of the uterus. Relaxin hormone relaxes the
pelvic ligaments of mother to prepare for the
childbirth.
Å
The mammary glands in females undergo
differentiation during pregnancy. The production and
release of milk by the mammary glands of female after
birth of a young one is called lactation.
Å
The first milk, which comes out from the mother’s
mammary glands just after childbirth is called
colostrum. It is rich in proteins and energy along with
the antibodies that provide passive immunity to the
newborn.
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Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1 ~ Male Reproductive System
1 Pouch in which testes are suspended outside the
abdominal cavity, is
(a) tunica albuginea
(c) epididymis
vasa efferentia by
(b) inguinal canal
(d) scrotum
2 Function of scrotum is to maintain the
(a)
(b)
(c)
(d)
(b) 5-6 cm and 3-4 cm
(d) 7-8 cm and 8-9 cm
4 How many compartments (approximately) are there in
each human testis?
(b) 300
(c) 350
(d) 400
5 Compartments in mammalian testes are called
(a) testicular lobules
(c) Sertoli cells
(b) seminiferous tubules
(d) interstitial cells
6 Testicular lobules contain
(a)
(b)
(c)
(d)
3-5 seminiferous tubules
2-6 seminiferous tubules
5-7 seminiferous tubules
1-3 seminiferous tubules
7 The seminiferous tubules of the testis is lined on its
NEET 2019, 16
(a) Seminiferous tubules → Rete testis → Vasa efferentia
→ Epididymis → Vas deferens → Ejaculatory duct →
Urethra → Urethral meatus
(b) Seminiferous tubules → Vasa efferentia → Epididymis
→ Inguinal canal → Urethra
(c) Testis → Epididymis → Vasa efferentia → Vas
deferens → Ejaculatory duct → Inguinal canal →
Urethra → Urethral meatus
(d) Testis → Epididymis → Vasa efferentia → Rete testis
→ Inguinal canal → Urethra
13 Choose the incorrect pair.
(a)
(b)
(c)
(d)
Leydig cells — Secrete testicular hormone
Vasa efferentia and epididymis — Accessory ducts
Vas deferens — Loops over the urinary bladder
Ejaculatory duct — Vasa efferentia and seminal vesicle
14 Choose the correct option.
C
AIIMS 2019
B
D
inside by
(a) spermatocytes
(c) cells of Sertoli
(b) rete testis
(d) seminiferous tubules
cells in male reproductive system.
3 Approximate length and width of testis are
(a) 250
(a) vasa deferentia
(c) epididymis
12 Select the correct sequence for transport of sperm
temperature of testes
body temperature
level of growth hormone
level of male hormone
(a) 4-5 cm and 2-3 cm
(c) 6-7 cm and 4-5 cm
11 The seminiferous tubules of the testis open into the
(b) spermatogonia
(d) Both (b) and (c)
8 ……… provide nutrition to the male germ cells.
(a)
(b)
(c)
(d)
Interstitial cells
Leydig cells
Sertoli cells
Both (a) and (b)
A
9 Which of the following cells present in the
mammalian testes forms the sperms?
(a) Leydig cells
(c) Interstitial cells
(b) Spermatogonia
(d) Sertoli cells
(a) A– Testis–possesses 3-4 testicular lobule
(b) B– Seminal vesicle–storage of sperm
(c) C– Vas deferens–helps in sperm transfer
(d) D– Prostate gland–secretes seminal fluid
15 The shared terminal duct of the reproductive and
urinary system in the human male is
CBSE-AIPMT 2014
10 Region outside the seminiferous tubules is called
(a) interdigital space
(c) interstitial space
(b) interferous space
(d) blind space
(a) urethra
(c) vas deferens
(b) ureter
(d) vasa efferentia
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CHAPTER 03 > Human Reproduction
16 Identify A, B, C and D in the given diagram.
A
C
D
B
51
(a) A–Sertoli cells, B–Spermatozoa, C–Interstitial cells,
D–Sperms
(b) A–Sertoli cells, B–Secondary spermatocyte,
C–Interstitial cells, D–Spermatozoa
(c) A–Interstitial cells, B–Spermatogonia, C–Sertoli cells,
D–Sperms
(d) A–Sertoli cells, B–Spermatogonia, C–Interstitial cells,
D–Spermatozoa
19 The given digaram shows LS of testis showing
various parts. Identify the parts labelled (A-G) from
the list given below.
A
(a) A–Urinary bladder, B–Bulbourethral gland, C–Prostate
gland, D–Seminal vesicles
(b) A–Urinary bladder, B–Urethra, C–Vas deferens,
D–Bulbourethral gland
(c) A–Prostate gland, B–Seminal vesicles, C–Urinary
bladder, D–Bulbourethral gland
(d) A–Bulbourethral gland, B–Urinary bladder, C–Seminal
vesicles, D–Prostate gland
17 Identify the accessory glands found in males.
(a) Seminal vesicles
(c) Bulbourethral gland
(b) Prostate gland
(d) All of these
18 The given diagram refers to TS of testis showing
sectional view of a few seminiferous tubules. Identify
the parts labelled A-D and select the correct option.
D
A
B
C
B
G
C
D
F
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
E
Caput epididymis
Cauda epididymis
Vas deferens
Vasa efferentia
Corpus epididymis
Seminiferous tubules
Tunica vaginalis
Tunica albuginea
Tunica vasculosa
Rete testis
Codes
A
(a) II
(b) V
(c) I
(d) I
B
III
IV
IV
VI
C
IV
III
X
IV
D
X
VI
III
III
E
VI
I
II
V
F
I
X
VI
X
G
IX
VII
VIII
IX
TOPIC 2 ~ Female Reproductive System
20 The ovaries are located one on each side of the…A….
Each ovary is about 2-4 cm in length connected to the
…B… wall by …C… . Each ovary is covered by a
thin epithelium which encloses the ovarian stroma.
Stroma is divided into two zones …D… and …E… .
Fill the suitable choices for A-E.
(a) A–inner medulla, B–peripheral cortex, C–ligaments,
D–pelvic wall, E-lower abdomen
(b) A–lower abdomen B–pelvic, C–ligaments,
D–peripheral cortex, E–inner medulla
(c) A–pelvic wall, B–lower abdomen, C–ligaments,
D–inner medulla, E–peripheral cortex
(d) A–inner medulla, B–peripheral cortex, C–lower
abdomen, D–pelvic wall, E–ligaments
21 The following diagram refers to female reproductive
system of human. Identify A to E.
D
A
B
C
E
(a) A–Urethra, B–Urinary bladder, C–Uterus, D–Cervix,
E–Vagina
(b) A–Urethra, B–Urinary bladder, C–Uterus, D–Vagina,
E–Cervix
(c) A–Urethra, B–Urinary bladder, C–Uterus, D–Cervix,
E–Vagina
(d) A–Uterus, B–Urinary bladder, C–Urethra, D–Cervix,
E–Vagina
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Master The NCERT > BIOLOGY (Vol-II )
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22 Oviducts are also called
(a) Fallopian tubes
(c) vagina
31 Given the diagrammatic sectional view of mammary
gland. Identify A, B, C and D.
(b) uterus
(d) ovary
23 Human Fallopian tube is about
(a) 8-9 cm long
(c) 10-12 cm long
A
(b) 9-10 cm long
(d) 12-17 cm long
B
24 Funnel-shaped part of oviduct closer to the ovary is
C
called
(a) fimbriae
(c) ampulla
(b) infundibulum
(d) isthmus
25 Fimbriae are associated with which organ?
(a) Fallopian tube
(c) Vagina
26 The main function of fimbriae of Fallopian tube is
(a)
(b)
(c)
(d)
help in development of ovary
help in collection of the ovum after ovulation
help in development of ova
help in fertilisation
27 Choose the incorrect pair.
(a)
(b)
(c)
(d)
Finger-like projections – Fimbriae
Narrow part of oviduct – Ampulla
Part of oviduct joining the uterus – Isthmus
None of the above
28 The following diagram refers to the female
reproductive system of humans. Identify A-F.
F
A
B
C
D
E
(a) A–Ampulla, B–Isthmus, C–Infundibulum, D–Fallopian
tube, E–Ovary, F–Uterine fundus
(b) A–Isthmus, B–Infundibulum, C–Ampulla, D–Fallopian
tube, E–Ovary, F–Uterine fundus
(c) A–Isthmus, B–Ampulla, C–Infundibulum, D–Fallopian
tube, E–Ovary, F–Uterine fundus
(d) A–Ampulla, B–Infundibulum, C–Isthmus, D–Fallopian
tube, E–Ovary, F–Uterine fundus
29 Choose the incorrect pair.
(a) Cushion of fatty tissue covered by pubic hair
–Mons pubis
(b) Membrane covering opening of vagina–Hymen
(c) Finger-like structure above the urethral opening
–Clitoris
(d) Uterine layer exhibiting strong contraction during
delivery–Endometrium
30 The main tissue present in breast is ……… tissue.
(a) glandular
(c) ciliated
(b) squamous
(d) epithelium
D
JIPMER 2018
(b) Uterus
(d) Ovary
(a) A–Alveolus, B–Mammary duct, C–Lactiferous duct,
D–Areola
(b) A–Alveolus, B–Lactiferous duct, C–Mammary duct,
D–Areola
(c) A–Alveolus, B–Mammary duct, C–Lactiferous duct,
D–Lactogenic spot
(d) A–Fat, B–Mammary duct, C–Lactiferous duct,
D–Areola
32 Several mammary ducts join to form a wider
mammary ampulla, which is connected to
(a)
(b)
(c)
(d)
lactiferous duct
seminiferous duct
seminiferous tubules
nipple
33 Pick the odd one out from each series given below
and select the correct option.
I. Scrotum, rete testis, Fallopian tube, vas deferens.
II. Ovary, uterus, vagina, ejaculatory duct.
III. Acrosome, Graafian follicle, corpus luteum, cervix.
IV. Prostate, testis, seminal vesicles, Cowper’s gland.
I
(a) Vas deferens
(b) Rete testis
(c) Scrotum
(d) Fallopian
tube
II
Vagina
Ovary
III
Cervix
Graafian
follicle
Uterus
Corpus
luteum
Ejaculatory Acrosome
duct
IV
Cowper’s gland
Prostate
Seminal
vesicles
Testis
34 A sectional view of mammary gland shows
I. nipple and areola.
II. mammary lobes (alveolus) and duct.
III. ribs.
IV. ampulla and lactiferous duct.
Choose the correct option from the above.
(a) I, II, III and IV
(c) III, IV and II
(b) I, II and III
(d) I, IV and III
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CHAPTER 03 > Human Reproduction
53
TOPIC 3 ~ Gametogenesis
35 Number of chromosomes present in
44 The difference between spermiogenesis and
spermatogonium is
(a) 46
(b) 23
JIPMER 2019
(c) 48
(d) 43
36 Which cells come earliest in the sequence of sperm
production?
(a) Spermatozoa
(c) Spermatid
(b) Spermatocyte
(d) Spermatogonia
37 Which of the following undergoes meiosis-I division
during spermatogenesis?
(a) Primary spermatocytes (b) Secondary spermatocytes
(c) Sertoli cell
(d) Leydig cell
38 Number of chromosomes present in secondary
spermatocyte is
(a) 22
(b) 23
JIPMER 2019
(c) 24
(d) 25
39 Which one of the following cells have haploid
number of chromosome?
(a) Primary spermatocytes (b) Secondary spermatocytes
(c) Spermatid
(d) Both (b) and (c)
40 During spermatogenesis, which cells are the first to
contain haploid number of chromosomes?
(a)
(b)
(c)
(d)
Spermatogonium
Primary spermatocyte
Secondary spermatocyte
Spermatid
41 Find out spermatid and Sertoli cell in given below
diagram.
spermiation is
NEET 2018
(a) in spermiogenesis, spermatozoa from Sertoli cells are
released into the cavity of seminiferous tubules, while in
spermiation, spermatozoa are formed
(b) in spermiogenesis, spermatozoa are formed, while in
spermiation, spermatids are formed
(c) in spermiogenesis, spermatids are formed, while in
spermiation, spermatozoa are formed
(d) in spermiogenesis, spermatozoa are formed, while in
spermiation, spermatozoa are released through
seminiferous tubules
45 Spermatogenesis starts at puberty due to significant
increase in the secretion of
(a) GnRH
(c) testosterone
(b) prolactin
(d) oestrogen
46 GnRH, a hypothalamic hormone, needed in
reproduction, acts on
NEET 2017
(a) anterior pituitary gland and stimulates secretion of LH
and oxytocin
(b) anterior pituitary gland and stimulates secretion of LH
and FSH
(c) posterior pituitary gland and stimulates secretion of
oxytocin and FSH
(d) posterior pituitary gland and stimulates secretion of LH
and relaxin
47 Give the name of two hormones A and B in the figure
given below.
A
A
B
Acts on
Leydig
cells
(a) FSH and GH
(c) GH and LH
C
D
Secrete
B
Stimulate
spermatogenesis
(b) LH and androgens
(d) GH and lactin
48 Sperms of mammals depend for movement on
E
(a) only tail
(c) middle piece
F
(b) tail and middle piece
(d) Only head
49 Which one of the labelled part utilises fructose as a
source of energy?
(a) D and E (b) E and F (c) A and C
(d) B and E
Head
42 Spermiogenesis is
(a)
(b)
(c)
(d)
spermatids transformed into spermatozoa
spermatozoa transformed into spermatids
spermatozoa transformed to spermatocytes
spermatid to secondary spermatocytes
JIPMER 2019
Acrosome
Nucleus
Middle piece
Tail
43 What is the correct sequence of sperm formation?
NEET 2013
(a) Spermatid, Spermatocyte, Spermatogonia, Spermatozoa
(b) Spermatogonia, Spermatocyte, Spermatozoa, Spermatid
(c) Spermatogonia, Spermatozoa, Spermatocyte, Spermatid
(d) Spermatogonia, Spermatocyte, Spermatid, Spermatozoa
(a) Head
(c) Acrosome
(b) Tail
(d) Middle piece
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Master The NCERT > BIOLOGY (Vol-II )
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50 Choose the incorrect pair.
(a) Acrosome – Enzyme filled cap structure on sperm head
(b) Middle piece – Possesses numerous mitochondria
(c) Sperm tail – Facilitates sperm motility essential for
fertilisation
(d) Semen – Contains only sperms
51 Choose the incorrect pair.
D
F
(a)
Primary follicle
Secondary follicle
Corpus luteum
(b)
Secondary follicle
Graafian follicle
Corpus luteum
(c)
Tertiary follicle
Primary follicle
Secondary follicle
(d)
Tertiary follicle
Graafian follicle
Corpus luteum
56 Identify A, B and C in the figure given below.
(a) Antrum – Fluid-filled cavity in primary follicle
(b) Tertiary follicle – Primary oocyte completes its Ist
meiotic division inside it
(c) Secondary oocyte – Haploid cell formed after Ist
meiotic division
(d) Graafian follicle – Mature tertiary follicle which
ruptures during ovulation
A
I
Foetal life
B
secondary oocyte is called
zona granulosa
zona pellucida
plasma membrane
tertiary membrane
Adult
reproductive
life
53 Which of the following layers in an antral follicle is
acellular?
CBSE-AIPMT 2015
(a) Granulosa
(c) Stroma
(b) Theca interna
(d) Zona pellucida
54 At which stage of the development, ovum is released
(b) Oogonium
(d) Ootid
55 Consider the figure given below.
C
B
(a)
(b)
(c)
(d)
C
First
polar body
III
Ovum
Second
polar body
A–Secondary oocyte, B–Oogonia, C–Primary oocyte
A–Oogonia, B–Primary oocyte, C–Secondary oocyte
A–Secondary oocyte, B–Primary oocyte, C–Oogonia
A–Oogonia, B–Secondary oocyte, C–Primary oocyte
57 Mark the wrong item in each series and select the
from the ovary of the human female?
(a) Primary oocyte
(c) Secondary oocyte
II
Birth
Childhood
Puberty
52 The new membrane formed by follicular cells in
(a)
(b)
(c)
(d)
C
A
D
correct option.
I. Spermatocyte, polar body, spermatid,
spermatogonium
II. Endometrium, corpus luteum, acrosome, Graafian
follicle
III. Vas deferens, Fallopian tube, epididymis, Cowper’s
gland
IV. Testes, prostate, seminal vesicles, Cowper’s gland
I
(a) Spermatid
E
F
Select the option which correctly identifies the parts
labelled as C, D and F.
II
III
IV
Endometrium Epididymis
Prostate
(b) Polar body
Acrosome
Testes
(c) Spermatocyte
Corpus luteum Vas deferens
(d) Spermatogonium Graafian
follicle
Fallopian tube
Cowper’s
gland
Cowper’s gland Seminal
vesicles
TOPIC 4~ Menstrual Cycle
58 The reproductive cycle in the female primates such as
60 Menstrual flow occurs due to the lack of
monkeys, apes and human beings is called
(a) menstrual cycle
(c) circadian cycle
(b) oestrus cycle
(d) ovulatory cycle
59 The first menstruation that begins at puberty is called
(a) menopause
(c) gametogenesis
(b) ovulation
(d) menarch
CBSE-AIPMT 2012
(a) progesterone
(c) oxytocin
(b) FSH
(d) vasopressin
61 In an ideal menstrual cycle, the menstrual phase last
for
(a) 3-5 days (b) 5-6 days (c) 1-3 days
(d) 2-3 days
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CHAPTER 03 > Human Reproduction
55
62 A regular cycling woman is not menstruating, which
71 The main function of mammalian corpus luteum is to
one of the following is the most likely to be the root
cause?
(a) Maintenance of the hypertrophical endometrial lining
(b) Maintenance of high concentration of sex-hormones in
the bloodstream
(c) Regression of well-developed corpus luteum
(d) Fertilisation of the ovum
produce
72 Endometrium, epithelial glands and connective tissue
of uterus are broken due to the
63 What happens during the follicular phase of
(a) lack of oestrogen
(c) lack of FSH
menstrual cycle?
(a)
(b)
(c)
(d)
Proliferation of endometrium
Reduction in blood supply to endometrium
Regression of endometrium
No effect on endometrium
64 Level of LH is maximum
one of the following is likely to happen?
(a)
(b)
(c)
(d)
JIPMER 2019
(a) Proliferative phase–Rapid regeneration of myometrium
and maturation of Graafian follicle
(b) Secretory phase–Development of corpus luteum and
increased secretion of progesterone
(c) Menstruation–Breakdown of endometrium
(d) Ovulation–LH and FSH attain peak level and cause
rupture of Graafian follicle
female?
(b) 14-16 days
(d) 20-26 days
66 Rapid secretion of LH in ovulatory phase causes
rupturing of Graafian follicle
release of ova
ovulation
All of the above
75 Correct sequence of secretion of hormone from
beginning of menstrual cycle to the end is
(a)
(b)
(c)
(d)
67 Which of the following events is not associated with
ovulation in human female?
(a)
(b)
(c)
(d)
Corpus luteum will degenerate
Oestrogen secretion further decreases
Primary follicle starts developing
Progesterone secretion rapidly increases
74 Which of them is not a correct match?
65 When does ovulation occur in a healthy menstruating
(a)
(b)
(c)
(d)
(b) lack of progesterone
(d) excess of FSH
73 If the mammalian ovum fails to get fertilised, which
(a) just before ovulation
(b) just after ovulation
(c) at the time of ovulation
(d) during menstrual bleeding phase
(a) 9-14 days
(c) 16-28 days
CBSE-AIPMT 2014, 1995
(a) oestrogen only
(b) progesterone only
(c) human chorionic gonadotropin
(d) relaxin only
CBSE-AIPMT 2015
FSH, progesterone, LH
oestrogen, FSH and progesterone
FSH, oestrogen, progesterone
oestrogen, progesterone, FSH
76 Read the graph and correlate the uterine events that
Decrease in oestradiol
Full developement of Graafian follicle
Release of secondary oocyte
LH surge
take place according to the hormonal levels on
A. 6-15 days, B. 16-25 days, C. 3-5 days (if the ovum
is not fertilised).
menstrual cycle because
(a)
(b)
(c)
(d)
NEET (Odisha) 2019
follicles do not remain in the ovary after ovulation
FSH levels are high in the luteal phase
LH levels are high in the luteal phase
Both (b) and (c)
69 Formation of corpus luteum is induced by
JIPMER 2018
(a) LH
(b) oestrogen
(c) FSH
(d) progesterone
Oestrogen
Progesterone
1
70 A temporary endocrine gland in the human body is
NEET 2017
(a) pineal gland
(c) corpus luteum
Ovarian hormone levels
68 No new follicles develop in the luteal phase of the
(b) corpus cardiacum
(d) corpus allatum
5
10
15
Days
20
25
29
(a) A–Degeneration of endometrium, B–Myometrium
thickness, becomes vascularised ready to receive and
implant embryo, C–Regeneration of endometrium
(b) A–Degeneration of endometrium, B–Endometrium
thickness increases, becomes vascularised, ready to
receive and implant ovum, C–Regeneration of
endometrium
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Master The NCERT > BIOLOGY (Vol-II )
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(c) A–Regeneration of endometrium, B–Endometrium
becomes thick and vascularised ready to receive and
implant embryo, C–Degeneration of endometrium
(d) A–Regeneration of myometrium, B–Endometrium
becomes thick and vascularised, ready to receive and
implant embryo, C–Degeneration of endometrium
77 The following graph of relative concentrations of the
C
A
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 2122 23 24 25 26 27 28
Days
(a)
(b)
(c)
(d)
High
High
(b) High
(c) Low
(d) Low
High
Low
Low
High
Low
High
(a)
A–FSH, B–Progesterone, C–LH, D–Oestrogen
A–LH, B–Progesterone, C–FSH, D–Oestrogen
A–FSH, B–Oestrogen, C–LH, D–Progesterone
A–LH, B–Oestrogen, C–FSH, D–Progesterone
Increasing thickness
of endometrium
endometrium during a normal menstruation. Identify
A and B.
B
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
Days
(a)
(b)
(c)
(d)
Progesterone
Low
High
Low
High
Low
Low
High
Low
hormone concentration which occurs during the
menstrual cycle. Match A, B, C, D, E, F, G and H of
graph with the hormones and events given below.
A
B
C
FSH
0
7
14
21
D
0
7
14
Time/days
F
A
(a) IV
(b) VIII
(c) VIII
(d) I
E
21
G
Hormones and Events
I. Oestrogen
II.
III. Repair of endometrium IV.
V. Menstruation
VI.
VII. Progesterone
VIII.
B
I
III
VI
III
C
VI
IV
IV
V
D
V
II
I
VII
28
28
H
Ovulation
Luteinizing hormone
Luteal phase
Ovarian phase
E
F
G
III
VIII VII
I
VI VII
VII III
II
VIII VI
IV
H
II
V
V
II
81 Some important events in the human female
A–Ovulation, B–Menopause
A–Ovulation, B–Menstruation
A–Menstruation, B–Ovulation
A–Menopause, B–Ovulation
79 The events of the menstrual cycle are represented
below. In which of the following options the level of
FSH, LH and progesterone is mentioned correctly?
Proliferative phase
or
Follicular phase
(5-15 days)
Menstruation
(1-5 days)
Low
High
High
LH
80 The diagram shows some of the changes in blood
78 The diagram shows the changes that take place in the
A
LH
D
B
20-28 Days
Proges
FSH
-terone
Low
Low
FSH
Hormone concentration in the
blood/arbitrary units
Increasing concentration
of hormone
four hormones present in the blood plasma of a
woman during her menstrual cycle. Identify the
hormones A, B, C and D.
13-14 Days
Luteal phase
or
Secretory phase
(16-28 days)
reproductive cycle are given below. Arrange the
events in proper sequence.
I. Secretion of FSH.
II. Growth of corpus luteum.
III. Growth of the follicle and oogenesis.
IV. Ovulation.
V. Sudden increase in the levels of LH.
Choose the correct option.
(a)
(b)
(c)
(d)
III → I → IV → II → V
I → III → V → IV → II
I → IV → III → V → II
II → I → III → IV → V
82 Cessation of menstrual cycle at the age of 50 is called
(a) ovulation
(c) menses
(b) gametogenesis
(d) menopause
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CHAPTER 03 > Human Reproduction
57
TOPIC 5 ~ Fertilisation and Implantation
83 Capacitation occurs in
(a) rete testis
(c) vas deferens
NEET 2017
(b) epididymis
(d) female reproductive tract
84 Fertilisation in humans is practically feasible only if
NEET 2016
(a) the ovum and sperms are transported simultaneously to
ampullary-isthmic junction of the Fallopian tube
(b) the ovum and sperms are transported simultaneously to
ampullary-isthmic junction of the cervix
(c) the sperms are transported into cervix within 48 hrs of
release of ovum in uterus
(d) the sperms are transported into vagina just after the
release of ovum in Fallopian tube
91 Cleavage is the rapid mitotic division occurring on
the way through isthmus to oviduct. It occurs in
(a) gametes
(c) sperm
(b) zygote
(d) ova
92 Cleavage forms 2-4-8-16 cells. These cells are called
(a) blastocysts
(c) morula
(b) blastomeres
(d) trophoblast
93 Embryo at 8-16 cells stage is called
(a) blastula
(c) trophoblast
(b) morula
(d) All of these
94 Study the chart given below.
Blastocyst
Contains two types of cell
85 Everytime copulation does not lead to fertilisation and
pregnancy because of failure of sperm to reach the
(a) ampulla
(c) endometrium
(b) cervix
(d) myometrium
A
86 During fertilisation, a sperm comes in contact with
the zona pellucida layer of the ovum and induces
changes in the membrane that block the entry of
…A… . The secretions of the …B… help the sperm
enter into the cytoplasm of the ovum.
(a)
(b)
(c)
(d)
A
eggs
eggs
additional sperms
additional sperms
B
zona pellucida
acrosome
acrosome
zona pellucida
87 What is acrosomal reaction?
B
Select the option containing the correct identify of A
and B.
(a)
(b)
(c)
(d)
A–Trophoblast, B–Inner cell mass
A–Placenta, B–Embryoblast
A–Placenta, B–Trophoblast
None of the above
95 Trophoblast of blastocyst attaches to the
(a) endometrium
(c) perimetrium
JIPMER 2018
(a) Contact of sperms with eggs
(b) Digestion of zona pellucida
(c) Disintegration of acrosome
(d) Contact of acrosome and nucleus of egg
(b) myometrium
(d) mesoderm
96 Inner cell mass or embryoblast gives rise to
(a) foetal part
(c) notochord
(b) embryo
(d) nourishment cell
97 The given diagram refers to ovum surrounded by few
sperms. Identify A, B and C in the diagram.
88 Extrusion of second polar body from egg nucleus
occurs
NEET 2019
(a) after fertilisation
(b) before the entry of sperm into ovum
(c) simultaneously with first cleavage
(d) after the entry of sperm but before fertilisation
89 In human females, meiosis-II is not complete until
CBSE-AIPMT 2014
(a) puberty
(c) uterine implantion
(b) fertilisation
(d) birth
90 The sex of the foetus will be decided at
(a)
(b)
(c)
(d)
fertilisation by male gamete
implantation
fertilisation by female gamete
the start of cleavage
C
A
B
(a) A–Zona pellucida, B–Perivitelline space, C–Corona
reticulata
(b) A–Zona pellucida, B–Vitelline membrane, C–Corona
radiata
(c) A–Zona pellucida, B–Perivitelline space, C–Corona
radiata
(d) A–Oolemma, B–Perivitelline space, C–Corona radiata
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Master The NCERT > BIOLOGY (Vol-II )
58
98 Consider the figure given below which depicts the
99 Identify A and B and their respective functions.
sequence of embryonic development in humans.
Identify E and G.
A
B
A
B
C
D
E
A
B
(a) Trophoblast Inner cell
mass
F
(a)
(b)
(c)
(d)
E
Morula
Morula
Gastrula
Gastrula
(b) Inner cell
mass
G
G
Blastula
Blastocyst
Blastocyst
Blastula
Function of A
Function of B
Gets attached to Differentiated as
the endometrium embryo
Trophoblast Gets attached to Differentiated as
the endometrium embryo
(c) Trophoblast Inner cell
mass
Differentiated as Gets attached to
embryo
the endometrium
(d) Ectoderm
Differentiated as Gets attached to
embryo
the endometrium
Endoderm
TOPIC 6 ~ Pregnancy and Embryonic Development
100 After implantation, finger-like projections appear on
the trophoblast called … A… . They are surrounded
by … B… and maternal blood.
Here, A and B refer to
(a)
(b)
(c)
(d)
A–chorion, B–foetal cell
A–chorionic villi, B–uterine tissue
A–uterine tissue, B–chorionic villi
A–foetal cell, B–chorion
101 Chorionic villi and uterine tissue become
interdigitated with each other and jointly form
(a) trophoblast
(c) placenta
(b) inner cell mass
(d) embryo
102 In the given diagram, find out A, B and C.
B
(c) A–Umbilical cord, B–Plug of mucus in cervix,
C–Placental villi
(d) A–Placental villi, B–Plug of mucus in
cervix,C–Umbilical cord
103 Several hormones like hCG, hPL, oestrogen,
progesterone are produced by
(a) ovary
(c) Fallopian tube
NEET 2016
(b) placenta
(d) pituitary
104 Hormones secreted by the placenta to maintain
pregnancy are
(a)
(b)
(c)
(d)
NEET 2018
hCG, hPL, progestogens, oestrogens
hCG, hPL, oestrogens, relaxin, oxytocin
hCG, hPL, progestogens, prolactin
hCG, progestogens, oestrogens, glucocorticoids
105 Which one is present in the urine of pregnant woman?
JIPMER 2018
(a) hCG
A
(b) LH
(c) Oestrogen
(d) FSH
106 Structure analogous to the placenta in mammals.
JIPMER 2019
(a) Chorion
C
(a) A–Plug of mucus in cervix, B–Placental villi
C–Umbilical cord
(b) A–Umbilical cord, B–Placental villi,C–Plug of mucus
in cervix
(b) Amnion (c) Yolk sac
(d) Allantois
107 Relaxin (a hormone) is secreted by
(a)
(b)
(c)
(d)
placenta
ovary
anterior lobe of pituitary
posterior lobe of pituitary
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CHAPTER 03 > Human Reproduction
59
108 Soon after implantation, the inner cell mass
111 Gastrulation means
differentiates into outer …A…, middle …B… and an
inner …C… . A, B and C in the given sentence are
(a)
(b)
(c)
(d)
A–mesoderm, B–ectoderm, C–endoderm
A–ectoderm, B–mesoderm, C–endoderm
A–ectoderm, B–endoderm, C–mesoderm
A–mesoderm, B–endoderm, C–ectoderm
112 The correct sequence is
109 Identify the correctly matched pair/pairs of the germ
layers and their derivatives.
I. Ectoderm – Epidermis II. Endoderm – Dermis
III. Mesoderm – Muscles IV. Mesoderm – Cartilage
V. Endoderm – Enamel of teeth
Choose the option containing the correctly matched pairs.
(a) I and IV
(b) I and II
(c) I, III and IV
(d) I, II, III and V
110 The amnion of mammalian embryo is derived from
(a)
(b)
(c)
(d)
NEET 2018
mesoderm and trophoblast
endoderm and mesoderm
ectoderm and mesoderm
ectoderm and endoderm
JIPMER 2019
(a) conversion of blastula into morula
(b) formation of three germ layers
(c) a phase in which organogenesis takes places
(d) a phase chracterised by inner cell mass
JIPMER 2018
(a) Zygote → Cleavage → Morula → Blastula → Gastrula
(b) Cleavage → Zygote → Morula → Blastula → Gastrula
(c) Zygote → Morula → Blastula → Cleavage → Gastrula
(d) Zygote → Blastula → Morula → Cleavage → Gastrula
113 Choose the incorrect pair.
Time of development in
foetus
Organ
(a) Heart
After one month of pregnancy
(b) Limbs and digits
By the end of second month
(c) External genital organs
By the end of 24 weeks
(second trimester)
(d) First movement of foetus
During the fifth month
TOPIC 7 ~ Parturition and Lactation
114 Parturition is induced by
118 Which one of the following is not the function of
placenta? It
(a) neural mechanism
(b) endocrine mechanism
(c) neuroendocrine mechanism
(d) hormonal mechanism
115 Signals for parturition originate from
CBSE-AIPMT 2012, 10
116 Identify the correct sequence in which the various
stages of parturition take place.
(a) Shedding of placenta → Dilation of cervix
→ Delivery of the baby
(b) Dilation of the cervix → Shedding of placenta
→ Delivery of the baby
(c) Dilation of the cervix → Delivery of the baby
→ Shedding of placenta
(d) None of the above
117 Which of the following hormones is responsible for
both the milk-ejection reflex and the foetal-ejection
NEET (Odisha) 2019
reflex?
(a) Oestrogen
(c) Oxytocin
(b) Prolactin
(d) Relaxin
119 Name A, B and C hormones in the given figure.
A
From ovaries
Induces oxytocin
receptors on
uterus
B
From mother’s posterior pituitary
Stimulates uterus to contract
Stimulates placenta to make
C
Stimulates more
contractions of uterus
(a)
(b)
(c)
(d)
Positive feedback
(a) Both placenta as well as fully developed foetus
(b) oxytocin released from maternal pituitary
(c) placenta
(d) fully developed foetus
NEET 2013
(a) facilitates supply of oxygen and nutrients to embryo
(b) secretes oestrogen
(c) facilitates removal of carbon dioxide and waste material
from embryo
(d) secretes oxytocin during parturition
A–Prostaglandin, B–Oxytocin, C–Oestrogen
A–Oestrogen, B–Oxytocin, C–Prostaglandin
A–Oestrogen, B–Prostaglandin, C–Oxytocin
A–Prostaglandin, B–Oestrogen, C–Oxytocin
120 Colostrum is important for newly born because
(a)
(b)
(c)
(d)
it contains essential antigen
it contains essential antibodies
Both (a) and (b)
it has more nutrients than ordinary milk
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Master The NCERT > BIOLOGY (Vol-II )
60
NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
128 Assertion (A) Menstrual phase is also compared to
■ Direction (Q. No. 121-135) In each of the following
questions, a statement of Assertion (A) is given and
followed by corresponding statement of Reason (R). Of
the statements, mark the correct answer as
(a) If both A and R are true and R is the correct
explanation of the A
(b) If both A and R are true, but R is not the correct
explanation of the A
(c) If A is true, but R is false
(d) If A is false, but R is true
129
130
121 Assertion (A) The testes are situated outside the
122
123
124
125
126
127
abdominal cavity within scrotum.
Reason (R) Muscles in scrotum helps to maintain
low temperature of testes, necessary for
spermatogenesis.
Assertion (A) In the testis, spermatogenesis occurs in
the seminiferous tubules and testosterone secretion
takes place from the Sertoli cells.
Reason (R) Testosterone brings growth and
maturation of secondary sex organs and also the
development of accessory sex characters.
Assertion (A) The Sertoli cells are present in
seminiferous tubules.
Reason (R) Sertoli cells provide nutrition to the germ
cells and spermatozoa.
Assertion (A) The bulbourethral gland is a male
accessory gland.
Reason (R) Its secretion helps in the lubrication of
the penis, thereby facilitating reproduction.
Assertion (A) Fimbriae are finger-like projections of
infundibulum part of oviduct which is closest to ovary.
Reason (R) They are important for the collection of
ovum after ovulation from ovary.
Assertion (A) In females, parturition is the act of
giving birth to a baby.
AIIMS 2018
Reason (R) Signals for parturition originate from a
fully developed foetus.
Assertion (A) Ovum retains most of the contents of the
primary oocyte and is much larger than a spermatozoa.
Reason (R) Ovum needs energy to go about in search
of a spermatozoa for fertilisation.
131
132
133
134
135
shedding tears for the lost ovum.
Reason (R) In the menstrual phase, loss of
endometrial lining takes place due to reduced titre of
progesterone.
Assertion (A) Production of FSH and LH increases
in the ovulation phase.
Reason (R) Due to decrease in the level of LH
ovulation (releasing of ova) takes place.
Assertion (A) Progesterone is essential for
maintenance of the endometrium.
Reason (R) Endometrium is essential for implantation
of fertilised ovum.
Assertion (A) Not all copulations lead to pregnancy.
Reason (R) Fertilisation can only occur if the ovum
and sperms are transported simultaneously to the
ampullary-isthmic junction.
Assertion (A) In humans, the gamete contributed by
the male determines whether the child produced will
be male or female.
Reason (R) Sex in humans is a polygenic trait,
depending upon a cumulative effect of some genes on
X-chromosome.
Assertion (A) Placenta is an endocrine gland.
Reason (R) It secretes many hormones essential for
pregnancy.
Assertion (A) The presence of hCG in woman urine
is the basis for pregnancy test.
Reason (R) A woman passes out hCG in the urine
during pregnancy.
Assertion (A) Breastfeeding during initial period of
infant growth is recommended.
Reason (R) Colostrum contains several antibodies,
essential to render immunity in newborns.
II. Statement Based Questions
136 Choose the correct statement.
(a) Size of testis is 4-5 cm in length and 1 cm in width
(b) The scrotum is maintained at body temperature
(c) The testes are situated outside the abdominal cavity in
humans
(d) The earliest stages of spermatogenesis occur outside the
testis
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CHAPTER 03 > Human Reproduction
137 Choose the incorrect statement (s).
(a) Oogonia are formed and added after birth
(b) Oogenesis is initiated during the embryonic development
(c) No more gamete mother cells are formed in females
after birth
(d) All of the above
138 Which of the following statement is incorrect?
(a) Each ovary is about 2 to 4 cm in length and is
connected to the pelvic wall and uterus by ligaments
(b) Each ovary is covered by a thin epithelium which
encloses the ovarian stroma
(c) Ovaries produce several steroid hormones only
(d) the stroma of ovary is divided into a peripheral cortex
and an inner medulla
139 Read the following statements.
I. The uterus is present in single pair and is also called
womb.
II. The shape of uterus is like an inverted pear.
III. The uterus opens into vagina through a narrow cervix.
IV. Birth canal is formed by cervical canal and vagina.
V. Perimetrium of uterus wall is external and thick,
myometrium is middle thin layer of smooth muscles
and endometrium is inner glandular layer.
Which of the above statements are correct ?
(a) I, II and III
(c) IV and V
(b) II, III and IV
(d) I and V
140 Read the following statements.
I. Spermatogonia and spermatids are diploid.
II. The extrusion of second polar body from nucleus
occurs after the entry of sperm and completion of
fertilisation.
III. Spermatogenesis and sperm differentiation under the
control of FSH and testosterone.
IV. A change in ovum after penetration of sperm the
formation of second polar body.
V. The secondary oocyte in the Graaffian follicle forms a
new membrane called zona pellucida surrounding it.
Which of the above statements are correct?
(a) I, II, III and V
(c) Only III
(b) I and III
(d) II, III, IV and V
141 Read the following statements.
I. Each testis has about 25 compartments called testicular
lobules.
II. Each testicular lobule contains one to three highly
coiled seminiferous tubules in which sperms are
produced.
III. Sertoli cells act as nurse cells of testicles.
IV. Sertoli cells are activated by FSH secreted by the
adenohypophysis.
Which of the above statements are incorrect?
(a) I and III
(b) Only I
(c) II and IV
(d) III and IV
61
142 Which of the following statement/s is not correct?
(a) The external opening of penis is called urethral meatus
(b) Glans penis is covered by loose fold of skin called
foreskin
(c) Secretion of bulbourethral gland helps in lubrication of
penis
(d) None of the above
143 Which of the following statement is false for uterus?
(a) It is also called womb and its shape is like an inverted
pear
(b) It is supported by ligaments attached to the pelvic wall
(c) It opens into oviducts through cervix whose cavity is
called cervical canal
(d) It is bound by three layers, outer perimetrium, middle
myometrium and inner endometrium
144 Which one of the following statement is false in
respect of viability of mammalian sperm?
CBSE-AIPMT 2012
(a) Sperm is viable for only up to 24 hrs
(b) Survival of sperm depends on the pH of the medium and
is more active in alkaline medium
(c) Viability of sperm is determined by its motility
(d) Sperms must be concentrated in a thick suspension
145 Which of the following statement is not correct for
oogonia?
(a)
(b)
(c)
(d)
They are million gamete mother cells
They are formed within each foetal ovary
They are formed throughout the life of female
They start division and get arrested at prophase-I of
meiotic division
146 Select the incorrect statement.
NEET 2016
(a) LH and FSH trigger ovulation in ovary
(b) LH and FSH decrease gradually during the follicular
phase
(c) LH triggers secretion of androgens from the Leydig
cells
(d) FSH stimulates the Sertoli cells which help in
spermiogenesis
147 Identify the correct statement(s) for placenta.
(a) It facilitates the supply of O 2 and nutrients to embryo
(b) It is connected to embryo through umbilical cord
(c) It removes CO 2 and excretory material produced by
embryo
(d) All of the above
148 Identify the correct statement on ‘inhibin’. NEET 2016
(a) It is produced by granulosa cells in ovary and inhibits
the secretion of FSH
(b) It is produced by granulosa cells in ovary and inhibits
the secretion of LH
(c) It is produced by nurse cells in testes and inhibits the
secretion of LH
(d) It inhibits the secretion of LH, FSH and prolactin
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Master The NCERT > BIOLOGY (Vol-II )
62
149 Select the correct option describing gonadotropin
activity in a normal pregnant female.
CBSE-AIPMT 2014, 12
(a) High level of FSH and LH stimulates the thickening of
endometrium
(b) High level of FSH and LH facilitates implantation of
the embryo
(c) High level of hCG stimulates the synthesis of oestrogen
and progesterone
(d) High level of hCG stimulates the thickening of
endometrium
150 Consider the following three statements related to the
human male reproductive system and select the
correct option stating which ones are True (T) and
which ones are False (F).
I. Middle piece of spermatozoon is also termed as power
house of spermatozoon.
II. Vas deferens joins a duct from seminal vesicle and
form vasa efferentia.
III. Semen is a collection of secretions from the seminal
vesicles, prostate gland, Cowper’s glands and sperms
from testes.
I
(a) T
(c) T
II
F
T
III
T
F
I
(b) F
(d) F
II
F
T
III
T
T
151 Read the following statements and select the correct
option(s).
I. Maintenance of hygiene and sanitation during
menstruation is very important.
II. Primary oocytes surrounded by a layer of granulosa
cells and called primary follicle.
III. Seminal plasma is rich in fructose, calcium and certain
enzymes.
IV. In females, uterus is single and also called womb.
(a) Only I
(c) Only III
II. Each spermatogonium in seminiferous tubule is
diploid and contains 46 chromosomes.
(a) Both statements are incorrect
(b) Statement I is correct, but statement II is incorrect
(c) Both statements are correct
(d) Statement I is incorrect, but statement II is correct.
154 Which of the following statements is correct?
I. Oogenesis is initiated during the embryonic
development stage .
II. At puberty only 60, 000-80, 000 primary follicles are
left in each ovary.
III. The primary follicles surrounded with many layers of
granulosa cells and form a new theca called secondary
follicles.
IV. Changing of sanitary napkins or pads after every
4-5 hours is necessary for maintaining menstrual
hygiene.
(a) I and II
(c) I and III
(b) I, II, III and IV
(d) None of these
155 Regarding male pronucleus which among the
following statement is correct?
I. It is the sperm nucleus after entering the ovum at
fertilisation.
II. Both head and neck of sperm contribute to pronucleus
formation.
III. Male pronucleus contains mitochondria.
IV. Sperm head contains pronucleus having diploid set of
chromosomes.
(a) Only II
(b) III and IV
(c) Only I
(d) II and IV
156 Study the figure of the human female reproductive
system given below.
C
(b) I and II
(d) All of these
D
B
152 Given below are four statements (I-IV) regarding
embryonic development in humans.
I. Cleavage divisions bring about considerable increase
in the mass of protoplasm.
II. With more cleavage divisions, the resultant
blastomeres become smaller and smaller.
III. The blastomeres in the blastocyst are arranged into two
layers, i.e. trophoblast and endometrium.
IV. Cleavage divisions result in a solid ball of cells called
morula.
Which of the above two statements are correct?
(a) I and III
(b) II and IV (c) I and II
(d) III and IV
153 Read the given statements and select the correct option.
I. The production of sperms and ovum by the testis in
males and the ovaries in female, respectively, called
gametogenesis.
E
A
Read the following statements and select the option
containing the incorrect statement(s).
I. A–ovary produces oestrogen required for the
development of female primary sex characters.
II. A–Vagina receives the penis during copulation.
III. B–Uterus serves as the site for implantation of the
fertilised egg.
IV. C–Oviduct serves as the site for fertilisation of the egg.
(a) I and II
(c) Only II
(b) Only I
(d) II and IV
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CHAPTER 03 > Human Reproduction
63
III. Matching Type Questions
161 Match the following columns.
Column I
(Layers of uterus)
157 Match the following columns.
Column I
(Events)
Column II
(Features)
Column II
(Features)
A. Perimetrium
1. Inner glandular layer of uterus
A. Parturition
1. Attachment of zygote to endometrium
B. Endometrium
2. External thin membrane of uterus
B. Gestation
2. Release of egg
C. Myometrium
3. Middle thick membrane of uterus
C. Ovulation
3. Delivery of baby
D. Implantation
4. Period between fertilisation and the birth
E. Fertilisation
5. Fusion of male and female gametes
Codes
A
(a) 2
(c) 3
Codes
A
(a) 2
(b) 4
(c) 5
(d) 3
B
4
3
1
4
C
1
1
2
2
D
5
5
3
1
Column II
A. Testis
1. Gives specific constituents to semen
B.
Vulva
2. Oogenesis
C.
Prostate fluid
3. Scrotum
Codes
A
(a) 3
(c) 4
C
1
2
D
2
1
B
2
3
C
3
1
D
1
2
Column II
(Related to)
A. Ovaries
1.
Fertilisation
B. Oviduct
2.
Ovulation
C. Uterus
3.
Pregnancy
D. Cervix
4.
Childbirth
A
(b) 1
(d) 2
B
2
3
C
3
1
Column II
1. Breakdown of endometrial lining
B. Secretory phase
2. Follicular phase
C. Menstruation
3. Luteal phase
Codes
A
(a) 2
(c) 3
B
3
2
C
1
1
A
(b) 1
(d) 3
D
4
2
C
3
4
Column I
D
4
1
Column II
A.
Acrosome
1.
Rudimentary tissue
B.
Endometrium
2.
Uterus
C.
Polar body
3.
Oogenesis
D.
Clitoris
4.
Spermatozoa
B
1
2
C
4
1
B
3
1
C
2
2
D
3
3
A
(b) 4
(d) 4
B
2
3
C
3
1
D
1
2
Column II
(Names)
A. Stage-I
1.
Menstrual phase
B.
Stage-II
2.
Follicular proliferative
C.
Stage-III
3.
Ovulatory phase
D. Stage-IV
4.
Luteal/Secretory phase
Codes
A
(a) 4
(b) 4
(c) 1
(d) 4
160 Match the following columns.
Codes
A
(a) 2
(c) 4
NEET 2018
163 Match the following columns.
A
(b) 4
(d) 4
Column I
(Female reproductive parts)
B
1
3
C
3
2
A. Proliferative phase
Column I
(Stages of menstrual cycle)
B
4
3
B
2
1
4. Labia majora
159 Match the following columns.
Codes
A
(a) 2
(c) 4
A
(b) 1
(d) 3
Column I
158 Match the following columns.
D. Production of ova
C
3
1
162 Match the following columns.
E
3
2
4
5
Column I
B
1
2
B
3
1
2
3
C
1
2
3
2
D
2
3
4
1
164 Match the following columns.
Column I
Column II
A.
Hyaluronidase
1.
Acrosomal reaction
B.
Corpus luteum
2.
Morphogenetic movements
C.
Gastrulation
3.
Progesterone
D.
Capacitation
4.
Mammary gland
E.
Colostrum
5.
Sperm activation
Codes
A
(a) 5
(b) 1
(c) 3
(d) 1
B
2
3
2
2
C
4
2
5
3
D
1
5
4
4
E
3
4
1
5
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Master The NCERT > BIOLOGY (Vol-II )
64
Codes
A
(a) 3
(b) 4
(c) 4
(d) 3
165 Match the following columns.
Column I
Column II
A.
Endometrium
1.
Copulation site
B.
Menopause
2.
Site of implantation
C.
Fallopian tube
3.
Stopping of menstruation
D.
Vagina
4.
Site of fertilisation
Codes
A
(a) 2
(c) 1
B
3
4
C
4
3
D
1
2
(b)
(d)
A
1
4
B
2
3
C
1
2
2
2
D
2
1
3
4
167 Match the following columns.
C
3
2
D
4
1
166 Match the following columns.
Column I
(Hormones)
B
4
3
1
1
Column II
(Functions)
A.
FSH
1.
Prepares endometrium wall for
implantation
B.
LH
2.
Develops female secondary sexual
characters
C.
Progesterone
3.
Maturation of Graafian follicle
D.
Oestrogen
4.
Maintenance of corpus luteum
Column I
NEET 2016
Column II
A.
Mons pubis
1. Embryo formation
B.
Antrum
2. Sperm
C.
Trophectoderm
3. Female external genitalia
D.
Nebenkern
4. Graafian follicle
Codes
A
(a) 3
(b) 3
(c) 3
(d) 1
B
4
4
1
4
C
2
1
4
3
D
1
2
2
2
NCERT & NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
NCERT
171 How many eggs do you think were released by the
ovary of a female dog which gave birth to 6
puppies?
168 Name the hormones involved in the regulation of
spermatogenesis.
(a) LH and FSH
(c) Testosterone and LH
(a) One
(c) Six
(b) Testosterone only
(d) LH only
169 Read the following statements.
I. Androgens are produced by Sertoli cells.
II. Presence or absence of hymen is not a reliable indicator
of virginity or sexual experience.
III. Leydig cells synthesise androgens.
IV. Oogenesis takes place in corpus luteum.
Identify whether the given above statements are true
or false.
I
(a) T
(c) F
II
F
T
III
F
T
IV
T
F
(b)
(d)
I
T
F
II
F
F
III
T
T
IV
F
T
170 How many eggs do you think would have been
released by human ovary if the mother gave birth to
identical twins?
(a)
(b)
(c)
(d)
One, fertilised by two sperms
Two, fertilised by different sperms
One, fertilised by single sperm
Two, fertilised by single sperm
(b) Three
(d) Indefinite
NCERT Exemplar
172 Spot the odd one out from the following structures
with reference to the male reproductive system.
(a)
(b)
(c)
(d)
Rete testis
Epididymis
Vasa efferentia
Isthmus
173 The vasa deferens receives duct from the seminal
vesicle and opens into urethra as
(a)
(b)
(c)
(d)
epididymis
ejaculatory duct
efferent ductule
ureter
174 Urethral meatus refers to the
(a)
(b)
(c)
(d)
urinogenital duct
opening of vas deferens into urethra
external opening of the urinogenital duct
muscles surrounding the urinogenital duct
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CHAPTER 03 > Human Reproduction
175 Seminal plasma, the fluid part of semen is
contributed by
I. seminal vesicle
II. prostate gland
III. urethra
IV. bulbourethral gland
(a) I and II
(c) II, III and IV
(b) I, II and IV
(d) I and IV
176 Which one of the following is not a male accessory
gland?
(a) Seminal vesicle
(c) Prostate
(b) Mammary gland
(d) Bulbourethral gland
177 Mature Graafian follicle is generally present in the
ovary of a healthy human female around
(a)
(b)
(c)
(d)
5-8 days of menstrual cycle
11-17 days of menstrual cycle
18-23 days of menstrual cycle
24-28 days of menstrual cycle
178 Spermiation is the process of the release of sperms from
(a) seminiferous tubules
(c) epididymis
(b) vas deferens
(d) prostate gland
179 Acrosomal reaction of the sperm occurs due to
(a)
(b)
(c)
(d)
its contact with zona pellucida of the ova
reactions within the uterine environment of the female
reactions within the epididymal environment of the male
androgens produced in the uterus
180 Which of the following hormones is not secreted by
human placenta?
(a) hCG
(c) Progesterone
(b) Oestrogens
(d) LH
181 Morula is a developmental stage
(a)
(b)
(c)
(d)
between the zygote and blastocyst
between the blastocyst and gastrula
after the implantation
between implantation and parturition
182 Match the following columns.
Column I
Column II
A. Trophoblast
1. Embedding of blastocyst in the endometrium
B. Cleavage
2. Group of cells that would differentiate as
embryo
C. Inner cell
mass
3. Outer layer of blastocyst attached to the
endometrium
D. Implantation
4. Mitotic division of zygote
Codes
A
(a) 2
(b) 3
(c) 3
(d) 2
B
1
4
1
4
C
3
2
2
3
D
4
1
4
1
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183 Choose the incorrect statement from the following.
(a) In birds and mammals, internal fertilisation takes
place
(b) Colostrum contains antibodies and nutrients
(c) Polyspermy in mammals is prevented by the chemical
changes on the egg surface
(d) In the human female, implantation occurs almost seven
days after fertilisation
184 Identify the correct statement from the following.
(a) High levels of oestrogen triggers the ovulatory surge
(b) Oogonial cells start to proliferate and give rise to
functional ova in regular cycles from puberty
onwards
(c) Sperms released from seminiferous tubules are highly
motile
(d) Progesterone level is high during the post ovulatory
phase of menstrual cycle
185 The spermatogonia undergo division to produce
sperms by the process of spermatogenesis.
Choose the correct one with reference to above.
(a) Spermatogonia have 46 chromosomes and always
undergo meiotic cell division
(b) Primary spermatocytes divide by mitotic cell division
(c) Secondary spermatocytes have 23 chromosomes and
undergo second meiotic division
(d) Spermatozoa are transformed into spermatids
186 Match between the following representing parts of the
sperm and their functions and choose the correct
option.
Column I
Column II
A.
Head
1. Enzymes
B.
Middle piece
2. Sperm motility
C.
Acrosome
3. Energy
D.
Tail
4. Genetic material
Codes
A
(a) 2
(c) 4
B
4
1
C
1
2
D
3
3
(b)
(d)
A
4
2
B
3
1
C
1
3
D
2
4
187 Which among the following has 23 chromosomes?
(a) Spermatogonia
(c) Secondary oocyte
(b) Zygote
(d) Oogonia
188 The membranous cover of the ovum at ovulation is
(a)
(b)
(c)
(d)
corona radiata
zona radiata
zona pellucida
chorion
189 Identify the odd one from the following.
(a) Labia minora
(c) Infundibulum
(b) Fimbriae
(d) Isthmus
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Master The NCERT > BIOLOGY (Vol-II )
66
Answers
‡ Mastering NCERT with MCQs
1 (d)
2 (a)
3 (a)
4 (a)
5 (a)
6 (d)
7 (d)
8 (c)
9 (b)
10 (c)
11 (b)
12 (a)
13 (d)
14 (c)
15 (a)
16 (b)
17 (d)
18 (d)
19 (c)
20 (b)
21 (d)
22 (a)
23 (c)
24 (b)
25 (a)
26 (b)
27 (b)
28 (c)
29 (d)
30 (a)
31 (d)
32 (a)
33 (d)
34 (a)
35 (a)
36 (d)
37 (a)
38 (b)
39 (d)
40 (c)
41 (d)
42 (a)
43 (d)
44 (d)
45 (a)
46 (b)
47 (b)
48 (b)
49 (d)
50 (d)
51 (a)
52 (b)
53 (d)
54 (c)
55 (d)
56 (b)
57 (b)
58 (a)
59 (d)
60 (a)
61 (a)
62 (d)
63 (a)
64 (c)
65 (b)
66 (d)
67 (a)
68 (a)
69 (a)
70 (c)
71 (b)
72 (b)
73 (a)
74 (a)
75 (c)
76 (c)
77 (c)
78 (c)
79 (a)
80 (c)
81 (b)
82 (d)
83 (d)
84 (a)
85 (a)
86 (c)
87 (b)
88 (d)
89 (b)
90 (a)
91 (b)
92 (b)
93 (b)
94 (a)
95 (a)
96 (b)
97 (c)
98 (b)
99 (a) 100 (b) 101 (c) 102 (b) 103 (b) 104 (a) 105 (a)
106 (a) 107 (b) 108 (b) 109 (c) 110 (c) 111 (b) 112 (a) 113 (c) 114 (c) 115 (a) 116 (c) 117 (c) 118 (d) 119 (b) 120 (b)
‡ NEET Special Types Questions
121 (a) 122 (d) 123 (b) 124 (a) 125 (b) 126 (b) 127 (c) 128 (a) 129 (c) 130 (b) 131 (a) 132 (c) 133 (b) 134 (a) 135 (a)
136 (c) 137 (a) 138 (c) 139 (b) 140 (d) 141 (b) 142 (d) 143 (c) 144 (a) 145 (c) 146 (b) 147 (d) 148 (a) 149 (c) 150 (a)
151 (d) 152 (b) 153 (c) 154 (b) 155 (c) 156 (b) 157 (d) 158 (a) 159 (a) 160 (b) 161 (a) 162 (a) 163 (c) 164 (b) 165 (a)
166 (a) 167 (b)
‡ NCERT & NCERT Exemplar Questions
168 (a) 169 (c) 170 (c) 171 (c) 172 (d) 173 (b) 174 (c) 175 (b) 176 (b) 177 (b) 178 (a) 179 (a) 180 (d) 181 (a) 182 (b)
183 (b) 184 (d) 185 (c) 186 (b) 187 (c) 188 (a) 189 (a)
Answers & Explanations
2 (a) The testes are suspended outside the abdominal
3
7
9
Answers & Explanations
10
cavity within a pouch called scrotum. Scrotum
maintains the temperature of testes, i.e. 2-2.5°C below
the body temperature, necessary for spermatogenesis.
(a) Each human testis is oval in shape, with a length of
about 4-5 cm and a width of about 2-3 cm.
(d) Each seminiferous tubule is lined on its inside by
two types of cells called male germ cells
(spermatogonia) and Sertoli cells.
(b) Spermatogonia or male germ cells undergo meiotic
divisions finally leading to sperm formation.
(c) Region outside the seminiferous tubules is called
interstitial space, contains small blood vessels and
interstitial cells or Leydig cells.
13 (d) Option (d) contains the incorrect pair. It can be
corrected as
Ejaculatory duct is formed by the union of vasa
deferentia and duct of the seminal vesicle.
Rest of the pairs are correct.
15
17
27
29
14 (c) Option (c) is the correct one. The correct
information about the remaining incorrect option is as
follows
Each testis (A) possesses about 250 compartments
called testicular lobules.
Seminal vesicle (B) secretes mucous and a watery
alkaline fluid rich in nutrients like fructose, citric acid,
32
inositol and prostaglandins. It provides energy to the
spermatozoa.
Prostate gland (D) releases an alkaline fluid that is rich
in citrate ions, calcium phosphate and proteolytic
enzymes to aid in sperm motility.
(a) The shared terminal duct of the reproductive and
urinary system in the human male is urethra. The
urethra is about 8 inches (20 cm) long and opens at the
end of the penis. The urethra provides an exit for urine
from the bladder as well as for as semen from vasa
efferentia during ejaculation.
(d) The accessory glands found in males are paired
seminal vesicles, the unpaired prostate gland and the
paired bulbourethral glands.
(b) Option (b) contains the incorrect pair. It can be
corrected as
Ampulla is the wider part of oviduct.
Rest all the pairs are correct.
(d) Option (d) contains the incorrect pair and can be
corrected as
Myometrium is the muscular layer of uterus which
exhibits strong contractions during delivery.
Endometrium is the glandular layer, which undergoes
cyclic changes during menstrual cycle.
Rest all the pairs are correct.
(a) Several mammary ducts join to form a wider
mammary ampulla which is connected to the lactiferous
duct through which milk is sucked out.
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CHAPTER 03 > Human Reproduction
35
37
40
43
44
45
46
48
49
In the first group, Fallopian tube is the odd one out as it
is a part of the female reproductive part. Rest are male
reproductive parts.
In the second series, ejaculatory duct is the odd one out
as it is a part of the male reproductive tract. Rest are
parts in females.
In the third series, acrosome is the odd one out as it is a
part of the sperm (male gamete). Rest are parts in
female.
In the fourth series, testis is odd one out as it is a
primary male reproductive organ. Rest are accessory
glands of male reproductive system.
(a) Spermatogonium is diploid (2n) and contains
46 chromosomes. These multiply by mitotic division to
form primary spermatocyte (2n).
(a) Primary spermatocytes (2n) undergo meiosis-I to
give rise to haploid secondary spermatocyes. The
secondary spermatocytes undergo meiosis-II to produce
spermatids which are then released as spermatids.
(c) Secondary spermatocytes are the first cells in
spermatogenesis in which the chromosome number
becomes half. Thus, they contain haploid number of
chromosomes.
(d) The correct sequence of sperm formation is
Spermatogonia → Spermatocyte → Spermatid →
Spermatozoa.
Spermatogonia are present on the inside wall of
seminiferous tubule which undergoes mitotic division
and increase their number. Primary spermatocytes are
some of the spermatogonia, which periodically undergo
meiosis and form secondary spermatocytes. These
undergo the second meiotic division to produce four,
equal haploid spermatids. The spermatids are further
transformed into spermatozoa (sperm) and are finally
released.
(d) Spermiogenesis is the process of transformation of
spermatids (n) into spermatozoa (n) or sperms. It
involves the differentiation phase in which one
spermatid develops into one spermatozoon.
Spermiation involves the release of sperms from
seminiferous tubules through Sertoli cells.
(a) Spermatogenesis is initiated at puberty due to the
increase in Gonadotropin Releasing Hormone (GnRH)
by hypothalamus.
(b) GnRH is a hypothalamic hormone. It stimulates the
anterior lobe of pituitary gland to secrete LH and FSH.
(b) Sperms of mammals depend for movement on tail
and middle piece. The middle piece possesses numerous
mitochondria, which produce energy for the movement
of tail that facilitates sperm motility essential for
fertilisation.
(d) The middle piece of the sperm utilises fructose as a
source of energy. It is packed with numerous
mitochondria which utilise fructose as a source of energy
to provide motility to sperm to reach out ovum (egg cell).
50 (d) Option (d) contains the incorrect match. It can be
51
53
57
58
60
63
64
67
68
corrected as
The combined secretion of three glands namely, seminal
vesicles, prostate gland, Cowper’s gland, together with
sperms collectively form semen.
Rest of the matches are correct.
(a) Option (a) contains the incorrect match. It can be
corrected as
Antrum is the fluid-filled cavity which is found in
tertiary follicle or Graafian follicle.
Rest of the matches are correct.
(d) The zona pellucida in an antral follicle is acellular. It
is a glycoprotein layer surrounding the plasma
membrane of the mammalian oocytes.
(b) Option (b) is correct.
In the first series, polar body is the odd one out as it is a
structure formed through oogenesis in females. Rest are
structure of spermatogenesis.
In the second series, acrosome is the odd one out as it is
a part of the sperm or the male gamete. Rest are parts in
females.
In the third series, Fallopian tube is the odd one out as it
is a part of the female reproductive system. Rest are
structure in males.
In the fourth series, testes is the odd one out as it is the
primary sex organ of the male reproductive system. Rest
are accessory glands of male reproductive system.
(a) The rhythmic series of changes that occurs in the
reproductive organs of female primates like monkeys,
apes and human beings, is called menstrual cycle.
It is repeated at an average interval of about 28/29 days.
(a) Menstrual flow occurs due to the lack of
progesterone. Progesterone is secreted by corpus luteum
and is essential for the maintenance of endometrium. In
the absence of progesterone, the endometrium starts to
degenerate. This leads to menstrual flow in which the
endometrial wall gets shed off.
(a) During the follicular phase of menstrual cycle, the
endometrium of the uterus regenerates through
proliferation.
(c) The level of LH is maximum at the time of ovulation
(i.e. ovulatory phase) in the menstrual cycle. It is called
as LH surge. It induces rupture of Graafian follicles and
thereby the release of ovum, i.e. ovulation.
(a) Decrease in oestradiol is not associated with
ovulation in human females. Oestradiol is also known as
oestrogen which is a primary female sex hormone.
During the ovulation in human females, level of
oestradiol increases. Its main function is to mature and
maintain the reproductive tract.
(a) No new follicles develop in the luteal phase of
menstrual cycle because after ovulation follicles do not
remain in the ovary. It is because during this phase,
Luteinizing Hormone (LH) and Follicle Stimulating
Hormone (FSH) levels decrease. Instead, the already
ruptured follicle closes after releasing the egg and forms
Answers & Explanations
33 (d) Option (d) is correct.
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Answers & Explanations
81
83
84
87
a corpus luteum during luteal phase, which produces
progesterone.
(a) The formation of corpus luteum is induced by LH
(Luteinizing Hormone). LH causes ovulation and
stimulates the remaining cells of the ovarian follicle to
develop corpus luteum.
(c) Corpus luteum is a temporary endocrine gland in the
human body. It secretes small amount of oestradiol and
significant amount of progesterone hormone. In the
absence of fertilisation, the corpus luteum degenerates.
(b) The main function of mammalian corpus luteum is
the secretion of progesterone, which is essential for the
maintenance of endometrium.
(a) Option (a) shows incorrect match. It can be
corrected as
Regeneration of endometrium under the influence of
oestrogen and maturation of Graafian follicle occurs
during the proliferative phase.
Rest of the options are correct matches.
(a) Option (a) depicts the correct levels of LH, FSH and
progesterone. On the 13-14 days (Proliferative phase)
FSH and LH have high concentration, whereas
progesterone has low concentration.
On the 20-28 days (Luteal phase), FSH and LH have
low concentration, whereas progesterone has high
concentration.
(b) The option depicting the correct sequence events
occurring in the female reproductive cycle is
I → III → V → IV → II.
In human female reproductive cycle or menstrual cycle,
during proliferative phase, the anterior lobe of pituitary
gland secretes the Follicle Stimulating Hormone (FSH),
which stimulates ovarian follicle to secrete oestrogen.
During the second week of reproductive cycle, most of
the developing follicle die and usually one follicle
continues to mature. Also, the Luteinizing Hormone
(LH) in blood level increases and a small surge of FSH
occurs. Ovulation takes place, which releases immature
egg into abdominal cavity.
During ovulation, the follicle breaks upon and collapses
under the continuous influence of Luteinizing Hormone
(LH). It begins to enlarge and forms a yellowish
structure called corpus luteum or yellow body.
(d) Capacitation is the process, where the spermatozoa
acquire the capacity to fertilise the eggs. It occurs in
female reproductive tract.
(a) Fertilisation in human, is practically feasible only if
the ovum and sperms are transported simultaneously at
the ampullary-isthmic junction of Fallopian tube. This is
the reason why every copulation does not lead to
fertilisation and pregnancy.
(b) Acrosomal reaction is the digestion of the zona
pellucida. It involves the progressive fusion of the
acrosomal membrane with the plasma membrane of the
sperm. It creates pores through which the acrosomal
enzymes can be released by exocytosis.
88
90
91
101
104
These enzymes include a protein digesting enzyme,
corona penetrating enzyme, zona lysin (acrosin) and
hyaluronidase. These enzymes allow the sperm to digest
and create a path through the zona pellucida to the
oocyte.
(d) Extrusion of second polar body from egg nucleus
occurs after the entry of sperm but before fertilisation.
The entry of sperm into female egg causes the
breakdown of Metaphase Promoting Factor (MPF) and
turns on Anaphase Promoting Factor (APF). Hence, the
secondary oocyte completes its meiotic division after
fertilisation and is said to be activated.
(a) The sex of the foetus will be decided at fertilisation
by male gamete. The chromosome pattern in the human
female is XX and in the male is XY. If the sperm
carrying X-chromosome fertilises the ovum, the zygote
would develop into a female and if Y fertilises the
ovum, the zygote would be a male. Thus, the sex of the
foetus depends on the type of chromosome present in
male gamete which fertilises the egg.
(b) Zygote divides rapidly by mitotic division when it
moves through the isthmus of the oviduct towards the
uterus. This rapid division is called cleavage.
(c) Chorionic villi and uterine tissue become
interdigitated with each other and jointly form a
structural and functional unit between the developing
embryo and the maternal body. This structure is called
placenta.
(a) Placenta acts as endocrine tissue and secretes the
following hormones to maintain pregnancy
l
l
l
human Chorionic Gonadotropin (hCG) It stimulates
and maintains the corpus luteum to secrete
progesterone until the end of pregnancy.
human Placental Lactogen (hPL) It is also known
Human Chorionic Somatomammotropin (HCS), it
stimulates the growth of mammary glands during
pregnancy.
Progesterone and oestrogen support foetal growth,
maintain pregnancy, inhibit uterine contractions, etc.
106 (a) Chorion serves as the structure analogous to
placenta in mammals. It completely encloses the
developing embryo and extraembryonic tissues like
placenta, it is also highly specialised to facilitate the
transfer of nutrients, gases and wastes between the
embryo and mother’s body. This is accomplished by
chorionic villi that emerge from the chorion and invade
the endometrium.
107 (b) Relaxin is secreted by the ovaries in the later phase
of pregnancy. Relaxin increases the flexibility of the
pubic symphysis and ligaments of the sacroiliac and
sacrococcygeal joints that help to dilate the cervix
during labour.
109 (c) Option (c) depicts the correctly matched pairs. Rest
of the incorrect pairs can be corrected as
l
l
Mesoderm gives rise to dermis.
Ectoderm gives rise to enamel of teeth.
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CHAPTER 03 > Human Reproduction
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112
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115
ectoderm and mesoderm. It is one of the extraembryonic
membrane which is formed by the amniogenic cells of
ectodermal origin on the inner side and somatopleuric
extraembryonic mesoderm on the outer side. This
membrane acts as a shock absorber for the foetus,
regulates foetal body temperature and prevents
desiccation.
(b) Gastrulation is a process by which blastocyst
transforms into the three layered (germ layers) structure
called gastrula. The three germ layers are inner
endoderm, middle mesoderm and outermost ectoderm.
These give rise to all the tissues and organs of the
developing foetus.
(a) The correct sequence of embryonic development is
Zygote → Cleavage → Morula → Blastula → Gastrula.
Fertilisation of the haploid egg by a haploid sperm gives
rise to a diploid zygote. At about 30-36 hrs after
fertilisation, the zygote divides into smaller cells by a
process called cleavage.
It is division of cells. It results in a solid ball of cells,
called morula. It is a 16-celled stage. It forms blastula
which is a 64-celled stage. It contains a fluid-filled
cavity called blastocoel. It ultimately leads to the
formation of multilayered gastrula.
(c) Option (c) contains the incorrect pair. It can
be corrected as
By the end of 12 weeks (first trimester), most of the
major organ systems like the limbs and external genital
organs are well-developed.
Rest of the options are correct pairs.
(a) The process of delivery of the foetus (childbirth) is
called parturition which is induced by a complex
neuroendocrine mechanism.
The signals for parturition originate from the fully
developed foetus and also from the placenta which
induce mild uterine contractions called foetal-ejection
reflex.
121 (a) Both Assertion and Reason are true and Reason is
122
123
124
125
126
127
117 (c) Oxytocin hormone is responsible for both the milk
ejection reflex and foetal-ejection reflex. It is a peptide
hormone normally produced in the hypothalamus and
released by the posterior pituitary gland.
118 (d) Option (d) is not correct function of placenta.
Pituitary secretes oxytocin during parturition. It is not a
function of the placenta.
The functions of placenta are to supply oxygen and
nutrients to embryo, secrete oestrogen, facilitate
removal of carbon dioxide and waste materials from
embryo.
120 (b) Colostrum is the milk produced during the initial
few days of lactation. It contains several essential
antibodies, which are absolutely essential to develop
resistance against pathogenicity in newborn. So, it is
recommended by doctors to feed newborn from breast
milk during the initial period of infant growth.
128
129
the correct explanation of Assertion.
The testes are situated outside the abdominal cavity
within a pouch called scrotum. The scrotum helps in
maintaining the low temperature of the testes (2-2.5°C)
lower than the normal internal body temperature
necessary for spermatogenesis.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
In the testis, spermatogenesis occurs in the seminiferous
tubules and testosterone secretion takes place in
interstitial cells.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Seminiferous tubule is lined on its inside by two types
of cells called male germ cells and Sertoli cells. The
male germ cells form sperm and Sertoli cells provide
nutrition to the germ cells.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
The bulbourethral gland is a male accessory gland. Its
secretions help in lubricating the penis to facilitate
reproduction.
(b) Both Assertion and Reason true, but Reason is not
the correct explanation of Assertion.
The correct explanation would be
Fimbrae are finger-like projections of infundibulum of
the oviduct which is closest to the ovary. Fimbrae
collect the released from ovary and move it down into
the Fallopian tube.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
The act of giving birth to a baby is called parturition. It
is induced by a complex neuroendocrine mechanism.
The signals originate from a fully developed foetus and
the placenta, which induces mild uterine contractions.
(c) Assertion is true, but Reason is false and it can be
corrected as
It is the sperm, which needs energy to move about in
female reproductive tract in search of ova so that
fertilisation can take place.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Menstrual phase is the phase of menstrual flow/menses
which continues for 3-5 days and involves discharge of
blood (a total of 50-100 mL) along with shedding off
endometrial lining (uterus, Fallopian tube and vagina)
due to reduced levels of both oestrogen and
progesterone hormones. As such menstrual phase is also
called funeral of unfertilised egg or shedding tears of
lost ovum.
(c) Assertion is true, but Reason is false. It can be
corrected as
In menstrual cycle, rapid secretion of LH leads to its
maximum level during mid-cycle. It is called LH surge.
It induces rupture of Graafian follicle, thereby releasing
ovum (ovulation).
Answers & Explanations
110 (c) Amnion of mammalian embryo is derived from
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70
130 (b) Both Assertion and Reason are true, but Reason is not
131
132
133
135
136
the correct explanation of Assertion.
Large amount of progesterone is essential for the
maintenance of the endometrium, to which fertilised
ovum gets attached (implantation).
(a) Both Assertion and Reason are true and Reason is the
correct explanation of Assertion.
All copulations do not lead to fertilisation as the
synchronisation of sperm and ova reaching the
ampullary-isthmic junction of the Fallopian tube is
important.
(c) Assertion is true, Reason is false. It can be corrected as
In human, the gametes contributed by the male
determines the sex of the child. Thus, sex in human is a
polygenic trait depending upon a cumulative effect of
some genes present on Y-chromosome and not on
X-chromosome.
(b) Both Assertion and Reason are true, but Reason is not
the correct explanation of Assertion.
Placenta acts as an endocrine tissue and produces several
hormones like hCG, hPL, oestrogens, progestogens, etc.,
which are essential for pregnancy.
(a) Both Assertion and Reason are true and Reason is the
correct explanation of Assertion.
Colostrum is the milk produced during the initial few
days of lactation. It is rich in antibodies essential to
render immunity for newborn babies. So, breastfeeding is
highly recommended during the initial period of infant
growth.
(c) The statement in option (c) is correct.
Rest of the statements are incorrect and can be corrected as
l
l
l
Size of testis is 4-5 cm in length and 2-3 cm in width.
The scrotum is maintained at a temperature 2-2.5°C
lower than normal body temperature.
The earliest stages of spermatogenesis occur within the
testis.
141 (b) Statement I is incorrect and can be corrected as
143
144
145
146
149
Each testis has about 250 compartments called
testicular lobules.
Rest of the statements are correct.
(c) Statement in option (c) represents the false
statement for uterus. It can be corrected as
It opens into vagina through a narrow cervix. The
cavity of the cervix is called cervical canal.
Rest of the statements are correct for uterus.
(a) Statement in option (a) is incorrect and can be
corrected as
Viability of a sperm means the capability of a sperm,
fertilising an egg. Sperms are viable for
24 hrs-48 hrs, whereas the ovum is viable for only 24
hrs.
Rest of the statements are correct.
(c) Statement in option (c) represents the incorrect
statement for oogonia and can be corrected as
Formation of millions of oogonia is initiated during
the embryonic development stage within each foetal
ovary, no more oogonia are formed and added after
birth.
Rest of the statements are correct.
(b) Statement in option (b) represents the incorrect
statement. It can be corrected as
The secretion of gonadotropins (LH and FSH)
increases gradually during the follicular phase and
stimulates follicular development as well as secretions
of oestrogens by growing follicles.
Rest of the statements are correct
(c) Statement in option (c) is correct. Rest of the
statements are incorrect and can be corrected as
l
l
Answers & Explanations
137 (a) The statement in option (a) is incorrect and can be
corrected as
Oogonia are formed in the female at the foetal stage and
no more oogonia are formed and added after birth.
Rest of the statements are correct.
138 (c) The statement in option (c) is incorrect and can be
corrected as
Ovaries produce several steroid hormones and the female
gamete (ovum).
139 (b) The statements II, III and IV are correct.
Statements I and V are incorrect and can be corrected as
l
l
The uterus is single and is also called womb.
Perimetrium of uterus is external and thin, myometrium
is the middle thick layer of smooth muscles and
endometrium is the inner glandular layer.
150 (a) The statements I and III are true, but II is false.
Statement II can be corrected as
Vas deferens joins a duct from seminal vesicle to form
ejaculatory duct.
152 (b) Statements II and IV are correct. Statements I and
III are incorrect and can be corrected as
l
l
Cleavage divisions bring about considerable decrease
in the mass of protoplasm.
Blastomeres arrange themselves to form inner cell
mass and trophoblast.
155 (c) Only statement I is correct regarding male
pronucleus. Others statements are incorrect and can be
corrected as
l
140 (d) Statements II, III, IV and V are correct.
l
Statement I is incorrect and can be corrected as
Spermatogonia are diploid and spermatids are haploid.
High levels of FSH and LH stimulates ovulation (not
the thickening of endometrium or implantation of the
embryo).
High levels of oestrogen stimulates the thickening of
the endometrium.
l
Only the head of the sperm contributes towards
pronucleus formation.
Male pronucleus lacks mitochondria.
Sperm head contains pronucleus having haploid set of
chromosomes.
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CHAPTER 03 > Human Reproduction
corrected as
D–Ovary produces oestrogen required for the
development of secondary sexual characters in females.
Rest of the statements are correct.
168 (a) LH and FSH regulate the process of
spermatogenesis. FSH acts on Sertoli cells whereas LH
acts on Leydig cells.
169 (c) Statements II and III and true. Statements I and IV
are false and can be corrected as
l
l
Androgens are produced by Leydig’s cells.
Oogenesis takes place in the ovary.
170 (c) Identical twins are produced from a single egg
171
172
173
174
175
176
177
179
(fertilised by single sperm) by the separation of early
blastomeres resulting from first zygotic cleavage. They
have same the genetic makeup.
(c) Dogs and rodents are polyovulatory species. In
these animals, more than one ovum is released from
ovary at the time of ovulation. Hence, six eggs were
released by the ovary of a female dog produce six
puppies.
(d) Isthmus is the odd one out of the given options as it
is a part of the Fallopian tube (of the female
reproductive system). Rest of the options, i.e. rete testis,
epididymis and vasa efferentia are a part of the male
reproductive system.
(b) The vas deferens joins a duct from the seminal
vesicle and opens into the urethra as the ejaculatory
duct. These ducts store and transport the sperms.
(c) The urethra originates from the urinary bladder and
extends through the penis to its external opening called
urethral meatus. In other words, it is the external
opening of the urinogenital duct.
(b) Seminal vesicles, prostate and the bulbourethral
glands are the male accessory glands whose secretions
constitute the seminal plasma (semen).
Urethra does not secrete semen. The transport of sperms
from the testis to the outside occurs through urethra.
(b) Mammary gland is a part of female reproductive
system. Rest are the male accessory glands.
(b) In humans, the menstrual cycle lasts for about
28/29 days. During 11–17 days of the menstrual cycle a
mature Graafian follicle is seen in healthy human
female.
(a) Binding of the sperm head to a receptor molecule on
the zona pellucida layer of the ova induces the
acrosome of the sperm to release its hydrolytic
enzymes.
180 (d) Placenta acts as an endocrine tissue and produces
several hormones like human chorionic gonadotropin,
oestrogen, progesterone, etc. LH is produced by the
anterior lobe of the pituitary gland.
181 (a) The embryo with 8-16 blastomeres is called a
morula. It is an embryonic developmental stage between
the zygote and the blastocyst.
183 (b) Statement in option (b) is incorrect and can be
corrected as
Colostrum contains several antibodies which are
absoutely essential to develop immunity in newborns.
Rest of the statements are correct.
184 (d) Option (d) represents the correct statement. Other
statements are incorrect and can be corrected as
l
l
l
Rapid secretion of LH leading to its maximum level
during the mid-cycle called LH surge.
Oogenesis is initiated during the early embryonal stage
when million of gamete mother cells (oogonia) are
formed within each foetal ovary, no more oogonia are
formed and added after birth.
Sperms released from epididymis are highly motile.
185 (c) Option (c) contains the correct statement. Rest of
the statements are incorrect and can be corrected as
l
l
l
Spermatogonia are diploid cells present on the inside
wall of seminiferous tubules that multiply by mitotic
divisions.
Primary spermatocyte undergo meiosis-I to give rise to
secondary spermatocytes (haploid).
Each secondary spermatocyte has 23 chromosomes and
undergoes meiosis-II to gives rise to two haploid
spermatids which are transferred to spermatozoa by
spermiogensis.
188 (a) The outermost membranous cover of the ovum at
ovulation is corona radiata. It is formed by follicular
cells. Inner to corona radiata is zona pellucida, which is
made up of three different glycoproteins secreted by the
ovum itself.
189 (a) Labia minora are paired folds of tissues under labia
majora which in turn surrounds the vaginal opening. It
is a part of the external genitalia of the female
reproductive system.
Fimbriae, infundibulum and isthmus along with ampulla
are parts of oviduct (Fallopian tube).
Answers & Explanations
156 (b) Statement I is the only incorrect statement. It can be
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CHAPTER > 04
Reproductive Health
NEET
Å
Å
KEY NOTES
According to World Health Organisation (WHO),
reproductive health means total well-being in all aspects of
reproduction, i.e. physical, emotional, behavioural and
social.
Therefore, a society with people having physically and
funtionally normal reproductive organs and normal
emotional and behavioural interactions among them in
all sex related aspects might be called reproductively
healthy.
Reproductive Health–Problems
and Strategies
Å
Å
Å
Å
Å
India initiated many action plans and programmes like
‘family planning’ (1951) at national level to attain total
reproductive health.
Currently, Reproductive and Child Healthcare (RCH)
programmes are under operation. RCH is an initiative to
create awareness among the people about reproduction
related aspects and providing facilities and support for
building up a reproductive healthy society.
Introduction of sex education in schools is also being
encouraged to provide right information to the young, so
as to discourage children from believes in myths and
misconception about sex-related aspects.
Proper information about reproductive organs,
adolescence and related changes, safe and hygienic
sexual practices and Sexually Transmitted Diseases
(STDs), it would help people to lead a reproductively
healthy life.
Successful implementation of various action plans have
improved reproductive health as indicated by better
awareness about sex related matters, increased number of
medically assisted deliveries, better detection and cure of
STDs, statutory ban on amniocentesis and overall
increased medical facilities for all reproduction related
problems.
Amniocentesis It is a technique used to find out genetic
disorders such as Down‘s syndrome, haemophilia, etc., in
developing foetus by using amniotic fluid.
It is also misused to check foetal sex. Sex-determination is based
on the chromosomal pattern in the amniotic fluid surrounding the
developing foetus.
A statutory ban has been implemented on this technique for
sex-determination to legally check increasing menace of female
foeticides.
Å
Å
Å
Population Stabilisation and Birth
Control
Å
Increased health facilities, rapid decline in death rate, Maternal
Mortality Rate (MMR) and Infant Mortality Rate (IMR) as well
as an increase in number of people in reproducible age and
better living conditions had an explosive impact on the growth
of population. This population explosion could lead to the
scarcity of even basic requirements like food, shelter, etc.
Å
The population growth can be controlled by motivating small
families, by using various contraceptive methods. Statutory
raising of marriageable age of the female to 18 years and male
to 21 years and incentives given to couples with small families
are two other methods to tackle population growth.
An ideal contraceptive should be user-friendly, easily
available, effective, reversible with no or least side effects. It
should also in no way interfere with sexual desire and sexual
act of the user.
Contraceptive methods could be divided into following categories
Å
1. Natural Methods
Å
It works on the principle of avoiding chances of ovum and
sperm meeting. It includes
Periodic abstinence in which couples avoid coitus from day
10 to 17 of menstrual cycle, as chances of fertilisation are
very high during this period.
n
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CHAPTER 04 > Reproductive Health
n
n
Withdrawal or Coitus interruptus in which male partner
withdraws penis from vagina just before ejaculation to
avoid insemination.
6. Surgical Methods
Å
Lactational amenorrhea method includes the absence of
menstruation after parturition and due to intense
lactation and no ovulation in this period, chances of
fertilisation is nil.
It is also called sterilisation. These are used as terminal
method of contraception in male and female to prevent
any more pregnancy by blocking gamete transport.
These include
n
2. Barrier Methods
Å
In this, ovum and sperms are prevented from physical
meeting with the help of barriers. These include
n
n
Å
Vasectomy is the surgical method in male, a small
part of the vas deferens is removed or tied up
through a small incision on the scrotum to prevent
release of sperms.
Condoms are barriers made up of rubber or latex sheath,
used to cover the penis in the male or vagina and cervix
in the female. They also prevent from STDs.
Vas deferens
tied and cut
Diaphragms, cervical caps and vaults are barriers made
of rubber that are inserted into the female reproductive
tract to cover the cervix during coitus.
Spermicidal creams, jellies and foams are usually used
along with these to increase their contraceptive efficiency.
These help to kill the sperms.
Vasectomy
3. Intra Uterine Devices (IUDs)
Å
Å
n
These are inserted by doctor or trained nurses into the
female uterus through vagina. IUDs may be non-medicated
(e.g. Lippes loop), copper releasing (Cu-T, Cu-7,
Multiload-375) and the hormone releasing (Progestasert,
LNG-20).
Tubectomy is the surgical method in females in
which small part of Fallopian tube is removed
surgically. These techniques are highly effective but
poorly reversible.
Fallopian tubes tied and cut
These IUDs increase phagocytosis of sperms within the
uterus, suppress the fertilising capacity and motility of
sperms and make the uterus unsuitable for implantation and
the cervix hostile to the sperms.
4. Oral Pills
Å
These are progesterone or progesterone-oestrogen
combination used by females in the form of tablets and hence
popularly called the pills.
Å
They inhibit ovulation and implantation as well as change
the quality of cervical mucus to prevent/retard entry of
sperms. For example, Saheli, developed by scientists at
Central Drug Research Institute (CDRI) Lucknow, India, is
once a week pill with non-steroidal preparation.
Å
Administration of pills within 72 hours of coitus is found to
be very effective as emergency contraceptives.
5. Injectable and Implants
Å
These are the methods in which progesterone alone or in
combination with oestrogen can be used by females under
the skin.
Å
Such injectables and implants are functionally similar to pills
and their effective period is much longer.
Tubectomy
Medical Termination of
Pregnancy (MTP)
Å
An intentional or voluntary termination of pregnancy
before full term or before the foetus becomes viable is
called Medical Termination of Pregnancy (MTP) or
induced abortion.
Å
Nearly 45 to 50 million, MTPs are performed in a year
all over the world which accounts to 1/5th of the total
number of conceived pregnancies in a year.
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KEY NOTES
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Master The NCERT > BIOLOGY (Vol-II )
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Å
Government of India legalised MTP in 1971 with some strict
conditions to avoid its misuse, especially to check
indiscriminate and illegal female foeticides, which are reported
to be high in India.
Å
The late detection leads to complications like Pelvic
Inflammatory Diseases (PIDs), abortions, still births,
ectopic pregnancies, infertility or even cancer of the
reproductive tract.
Å
The Medical Termination of Pregnancy (Amendment) Act,
2017 was enacted by the government of India with the
intension of reducing the incidence of illegal abortion and
consequent maternal mortality and morbidity.
Å
One should not panic because prevention from STIs is
possible and one could be free of these infections, by
following these simple principles as given below
Å
According to this Act, a pregnancy may be terminated on certain
considered grounds within the first 12 weeks of pregnancy on
the opinion of one registered medical practitioner. If the
pragnancy has lasted more than 12 weeks, but fewer than
24 weeks, two registered medical practitioners must be of the
opinion, formed in good faith, that the required ground exist.
Å
The grounds for such termination of pregnancies are
n
n
The continuation of the pregnancy would involve a risk to
the life of the pregnant woman or of grave injury physical
or mental health.
There is a substantial risk that of the child were born, it
would suffer from such physical or mental abnormalities as
to be seriously handicapped.
Sexually Transmitted
Infections (STIs)
Å
Å
Å
Diseases which are transmitted through sexual intercourse are
called Sexually Transmitted Infections (STIs) or Veneral
Diseases (VDs) or Reproductive Tract Infections (RTIs).
Genital herpes, syphilis, gonorrhoea, chlamydiasis, genital
warts, hepatitis-B and AIDS (caused by HIV) are some
common STIs.
STIs like hepatitis-B and HIV can also be transmitted by the
following
Sharing of contaminated injection needles, surgical
instruments, etc., with infected persons.
Transfusion of blood.
From infected mother to foetus.
n
n
n
Å
Å
Å
Å
Except for hepatitis-B, genital herpes and HIV infections, all
other diseases are completely curable, if detected early and
treated properly.
The early symptoms of STIs are minor and include itching, fluid
discharge, slight pain, swellings, etc., in the genital region.
Infected females may often be asymptomatic and hence may
remain undetected for long.
The patients remain undetected due to the following reasons
The absence or less significant symptoms in early stages of
infection.
Social stigma attached to the STIs.
n
n
NEET
(i) Avoid sex with unknown/multiple partners.
(ii) Always use condoms during coitus.
(iii) In case of doubt, consult a doctor as early as
possible for early detection and get completely
treated if diagnosed with disease.
Infertility
Å
Couples who are not able to produce children inspite
of unprotected sex are considered infertile. The
reason for this could be many physical, congenital,
diseases, drugs or even psychological.
Å
Various methods are now available to help such
couples. These techniques are together called Assisted
Reproductive Technologies (ARTs).
Å
In Vitro Fertilisation (IVF) is the fertilisation outside
the body followed by embryo transfer, which is
commonly called test tube baby programme.
n
Å
The zygote or early embryo (upto 8 blastomeres)
could be transferred into Fallopian tube called
ZIFT (Zygote Intra Fallopian Transfer) and embryo
with more than 8 blastomeres into the uterus called
IUT (Intra Uterine Transfer) to complete its further
development.
Embryos formed by in vivo fertilisation (fertilisation
within the female body) also could be used for such
transfer to assist those females who cannot conceive.
GIFT (Gamete Intra Fallopian Transfer) is the
transfer of gametes collected from a donor into
Fallopian tube of another female who do not
produce ovum.
ICSI (Intra Cytoplasmic Sperm Injection) is
specialised procedure to form an embryo in
laboratory in which sperm is directly injected into
the ovum.
n
n
n
Artificial Insemination (AI) used in the
infertility cases in which male partner is unable
to inseminate the female or have a very low
sperm counts (azospermia) in the ejaculates. In
this technique, semen collected from donor is
artificially introduced into the vagina or uterus
of the female by IUI (Intra Uterine Insemination).
KEY NOTES
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CHAPTER 04 > Reproductive Health
75
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1 ~ Reproductive Health–Problems and Strategies
1 Reproductive health is the well-being of
(a)
(b)
(c)
(d)
2 Family planning programme was initiated in
(a) 1951
(b) 1920
(c) 1930
(d) 1950
3 What is the full form of RCH?
(a)
(b)
(c)
(d)
5 Amniocentesis is the detection of
(a)
(b)
(c)
(d)
physical aspects
emotional and behavioural aspects
social aspects
All of the above
Reproductive and Child Healthcare
Reproduction, Contraception and Health
Reproduction and Child Health
None of the above
4 What are the various ways through which the
reproductive health can be improved?
I. Education
II. Awareness
III. Encouraging myths IV. Ban on amniocentesis
(a) I and II (b) II and III (c) III and IV (d) I, II and IV
chromosomal pattern by taking amniotic fluid
chorionic fluid from developing embryo
chromosomal pattern after childbirth
chromosomal pattern before fertilisation
6 Which of the following cannot be detected in a
developing foetus by amniocentesis?
NEET 2013
(a) Klinefelter’s syndrome
(b) Sex of the foetus
(c) Down’s syndrome
(d) Jaundice
7 Indicators of improved reproductive health of the
society are
(a)
(b)
(c)
(d)
better detection and cure of STDs
improved medical facilities
decreased maternal and infant mortality rates
All of the above
TOPIC 2 ~ Population Stabilisation and Birth Control
13 Natural methods of contraception are the natural
8 Population explosion is
(a)
(b)
(c)
(d)
increased frequency of diseases in population
rapid increase in population number
rapid decrease in population number
None of the above
9 India’s population cross 1 billion in
(a) May 2001
(c) May 2000
(b) Dec 1999
(d) Dec 1991
10 Causes for increased population growth in India is/are
(a)
(b)
(c)
(d)
increase in birth rate
decrease in maternal mortality rate
lack of education
All of the above
11 Which of the following are the consequences of over
population?
(a)
(b)
(c)
(d)
It increases the poverty of a country
It leads to shortage of food supply
It results in unemployment
All of the above
12 An ideal contraceptive should be
(a) user friendly
(c) Both (a) and (b)
(b) reversible
(d) decrease sexual drive
ways to
(a)
(b)
(c)
(d)
increase spermicidal activity
prevent fertilisation
decrease mortality
increase mortality
14 One of the legal method of birth control is
NEET 2013
(a) abortion by taking an appropriate medicine
(b) by abstaining from coitus from day 10-17 of the
menstrual cycle
(c) by having coitus at the time of day break
(d) by a premature ejaculation during coitus
15 Periodic abstinence is avoiding sex during
(a)
(b)
(c)
(d)
follicular phase
ovulatory phase
menstrual phase
None of the above
16 The lifespan of a sperm in female body is
(a) 1-2 days
(c) 4 days
(b) 3 days
(d) Only 1 day
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17 Coitus interruptus is the withdrawl method of natural
29 …A… makes the uterus unsuitable for implantation
contraception involving
and the cervix hostile to …B… .
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
withdrawl of penis from vagina before ejaculation
withdrawl of penis from vagina after ejaculation
sex during ovulation
no sex during ovulation
18 Lactational amenorrhea is the
(a)
(b)
(c)
(d)
30 The females wanting to delay pregnancy or space
absence of menses in adult age
absence of menses in elderly age
absence of menses during lactation
no menses during pregnancy
children should use
(a) Femidoms
(c) Tubectomy
(a) progesterone
(c) Both (a) and (b)
rubber/latex sheath which is used to cover
(b) cervix in female
(d) None of these
(b) for female use only
(d) None of these
21 Spermicidal creams are used in addition to condoms,
diaphragms, cervical cap and vaults for
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
(b) Cu-7
(d) Lippes loop
NEET 2019
35 Implants (the progesterone or progesterone-oestrogen
(b) Cu-7
(d) All of these
combination) are used by the females usually under
the
25 An injectible form of the hormone based
(a)
(b)
(c)
(d)
contraceptive is
(b) Depo-provera
(d) Saheli
26 Select the hormone releasing intrauterine devices.
(a) Multiload-375, Progestasert
(b) Progestasert, LNG-20
(c) Lippes loop, Multiload-375
(d) Vaults, LNG-20
A–ovulation, B–cervical mucus
A–oogenesis, B–structure
A–oogenesis, B–nucleus
A–spermatogenesis, B–cervical mucus
(a) is an IUD
(b) increases the concentration of oestrogen and prevents
ovulation in females
(c) blocks oestrogen receptors in the uterus preventing eggs
from getting implanted
(d) is a post-coital contraceptive
24 Example of copper releasing IUD is/are
(a) Norplant
(c) Mala-D
(b) A–21, B–7
(d) A–24, B–4
34 The contraceptive ‘Saheli’
23 Example of the non-medicated IUD is
(a) Cu-T
(c) Multiload-375
(a) A–27, B–1
(c) A–22, B–5
well as quality of …B… to prevent the entry of
sperms.
Inter Uterine Devices
Intra Uterine Devices
Inter Uterine Development
Intra Uterine Development
(a) Cu-T
(c) Multiload-375
starting preferably within first five days of menstrual
cycle. After a gap of …B… days, it has to be repeated
in the same pattern.
33 Oral contraceptives inhibit …A… and implantation as
lubrication
killing germs
increasing contraceptive effectiveness
None of the above
22 IUDs stands for
(a)
(b)
(c)
(d)
(b) oestrogen
(d) None of these
32 Pills have to be taken daily for period of …A… days
20 Diaphragms, cervical caps and vaults are
(a) non-usable
(c) for male use only
(b) IUDs
(d) Vaults and caps
31 Oral contraceptives have hormonal preparation of
19 Condoms or Femidoms are made up of thin
(a) penis in male
(c) Both (a) and (b)
A–Hormone releasing IUD; B–spermatogonia
A–Hormone releasing IUD; B–sperms
A–Sperms; B–hormonal releasing IUD
A–Sperms; B–ova
NEET 2019
skin of the inner arm above elbow
vagina
upper skin of stomach
cervix
36 Choose the correct option from A, B and C.
27 Copper releasing IUDs are used for suppressing the
(a) activity of ova
(b) activity of the uterus
(c) motility of the sperms (d) motility of ova
28 Lippes loop prevent contraception by
(a) preventing ovulation
(b) phagocytosis of sperms
(c) suppressing sperm motility (d) All of these
A
(a)
(b)
(c)
(d)
B
C
A–Condoms, B–Copper-T, C–Implants
A–Tubectomy, B–Implants, C–Copper-T
A–Vasectomy, B–Condoms, C–Copper-T
A–Copper-T, B–Condoms, C–Implants
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CHAPTER 04 > Reproductive Health
77
37 Administration of progesterone, progesterone-
oestrogen combination or IUDs are effective within
…… hours of coitus.
(a) 72
(b) 48
(c) 24
(d) 96
42 Which of the following approaches does not give the
defined action of contraceptive?
(a) Intra uterine
devices
Increase phagocytosis of sperms,
suppress sperm motility and fertilising
capacity of sperms
(b) Hormonal
contraceptives
Prevent/ retard entry of sperms, prevent
ovulation and fertilisation
38 What is the difference in oral contraceptives and
hormonal implants?
(a)
(b)
(c)
(d)
They differ in their sites of implantation
They differ in their duration of action
Both (a) and (b)
None of the above
(c) Vasectomy
Prevents spermatogenesis
(d) Barrier methods
Prevent fertilisation
43 What is the figure given below showing in particular?
39 Which of the following contraceptive methods do
involve a role of hormone?
(a)
(b)
(c)
(d)
NEET 2016
CBSE-AIPMT 2012
NEET 2019
Barrier method, lactational amenorrhea, pills
Cu-T, pills, emergency contraceptives
Pills, emergency contraceptives, barrier methods
Lactational amenorrhea, pills, emergency
contraceptives
40 Tubectomy is a method of sterilisation in which
CBSE-AIPMT 2014
(a) small part of the Fallopian tube is removed or tied up
(b) ovaries are removed surgically
(c) small part of vas deferens is removed or tied up
(d) uterus is removed surgically
41 Name the part cut and tied in male sterilisation. Also,
(a) Ovarian cancer
(b) Uterine cancer
(c) Tubectomy
(d) Vasectomy
44 Which of the following birth control measure can be
name the procedure.
considered as the most effective and reliable?
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
Vas deferens, tubectomy
Vas deferens, vasectomy
Vasa efferentia, tubectomy
Vasa efferentia, vasectomy
The rhythm method
Use of physical barriers
Intra uterine devices
Sterilisation techniques
TOPIC 3 ~ Medical Termination of Pregnancy and
Sexually Transmitted Infections
45 MTP stands for
(a)
(b)
(c)
(d)
Medical Termination of Pregnancy
Mental Trauma Phase
Menstrual Trauma Pain
Menstrual Temporary Pain
46 MTP helps to overcome pregnancy that result due to
(a)
(b)
(c)
(d)
rapes
unsafe sex
failure of contraceptives
All of the above
47 During which phase of the pregnancy MTP is safe?
(a)
(b)
(c)
(d)
1st trimester
2nd trimester
3rd trimester
4th trimester
48 MTP is of much risk in which phase of the
pregnancy?
(a) 2nd trimester
(c) 1st week
(b) 1st trimester
(d) 2nd week
49 MTP is being …A… to abort even normal foetus.
Specially when sex of the foetus is …B… .
Choose the correct option for A and B.
(a) A–used, B–male
(b) A–misused, B–female
(c) A–used, B–abnormal (d) A–misused, B–male
50 The other names for STIs or STDs are
(a) venereal diseases
(c) Both (a) and (b)
(b) reproductive tract infections
(d) None of these
51 Hepatitis-B and HIV spread through
(a) sharing needles
(b) transfusion of blood
(c) infected mother to child (d) All of these
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52 Which of the following sexually transmitted diseases
is not completely curable?
NEET 2019
(a) Genital warts
(b) Genital herpes
(c) Chlamydiasis
(d) Gonorrhoea
age group of
(a) 15-35 years
(c) 15-24 years
(b) 15-30 years
(d) 15-45 years
56 The timely detection of STIs is hindered by which of
53 Which of the following sexually transmitted diseases
do not specifically affect reproductive organs?
NEET (Odisha) 2019
(a) Genital warts and Hepatitis-B
(b) Syphilis and Genital herpes
(c) AIDS and Hepatitis-B
(d) Chlamydiasis and AIDS
the following factors?
(a)
(b)
(c)
(d)
Absence of advanced diagnostics
Social stigma attached to STIs
Initial asymptomatic condition of patients
Both (b) and (c)
57 The preventive measures of STIs include
(a)
(b)
(c)
(d)
54 STIs caused by bacteria include
(a) syphilis
(c) Both (a) and (b)
55 Incidence of STIs are very high among persons, in the
(b) gonorrhoea
(d) hepatitis
using condoms
avoid multiple sexual partner
hygienic sexual practices
All of the above
TOPIC 4 ~ Infertility
65 Difference between ZIFT and IUT lies in the
58 A couple can be infertile because of
(a) physical defect
(c) psychological defect
(b) congenital defect
(d) All of these
59 Assisted reproductive technology, IVF involves
transfer of
CBSE-AIPMT 2014
(a) ovum into the Fallopian tube
(b) zygote into the Fallopian tube
(c) zygote into the uterus
(d) embryo with 16 blastomeres into the Fallopian tube
60 IVF in which the early zygote with up to 8
blastomeres is transferred to the Fallopian tube is
called
(a) ZIFT
(c) ICSI
(b) GIFT
(d) IUI
CBSE-AIPMT 2012
(a) Intra Cytoplasmic Sperm Injection (ICSI)
(b) Intra Uterine Insemination (IUI)
(c) Gamete Intra Fallopian Transfer (GIFT)
(d) Zygote Intra Fallopian Transfer (ZIFT)
(a) Inter Uterine Transfer (b) Intra Uterine Transfer
(c) In-Uterus Transfer
(d) None of these
63 Embryo with more than 16 blastomeres formed due to
in vitro fertilisation is transferred into
NEET 2016
(b) Fallopian tube
(d) cervix
64 IVF in which embryo with more than 8 blastomeres is
transferred into female body is called
(a) IUT
(c) ZIFT
(b) GIFT
(d) ICSI
66 Specialised health care units help in diagnosis and
corrective treatment of disorders which result in
fertility. However, when such connections are not
possible, couples are advised
(a)
(b)
(c)
(d)
in vitro fertilisation
Artificial insemination
in vivo fertilisation
All of the above
(a) unable to produce eggs
(b) unable to support a foetus
(c) unable to provide suitable environment for fertilisation
and maturation of foetus
(d) All of the above
68 A childless couple can be assisted to have a child
62 IUT Stands for
(a) uterus
(c) fimbriae
methodology
nature of the sperms
nature of the cells
number of the cells
67 GIFT can be advised to couples where female partner is
61 The test tube baby programme employs which one of
the following techniques?
(a)
(b)
(c)
(d)
through a technique called GIFT. The full form of this
technique is
CBSE-AIPMT 2015
(a) Gamete Inseminated Fallopian Transfer
(b) Gamete Intra Fallopian Transfer
(c) Gamete Internal Fertilisation and Transfer
(d) Germ Cell Internal Fallopian Transfer
69 During ICSI technique,
(a)
(b)
(c)
(d)
fertilisation is done in vivo
embryo transfer is done at 32 blastomere stage
sperm directly injected into ovum
All of the above
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79
70 In case of a couple, where the male is having a very
low sperm count, which technique will be suitable for
NEET 2017
fertilisation ?
(a)
(b)
(c)
(d)
Intra Uterine Transfer
Gamete Intracytoplasmic Fallopian Transfer
Artificial Insemination
Intracytoplasmic Sperm Injection
(c) transfer of sperms to into Fallopian tube of surrogate
(d) transfer of sperms from husband/donor into a test tube
containing ova
72 The ‘ART’ in which the semen collected either from
the husband or a healthy donor and artificially
introduced either into the vagina or into the uterus is
71 Artificial insemination refers to
(a) artificial introduction of sperms from a donor into
female vagina
(b) direct introduction of sperms into ovaries
(a)
(b)
(c)
(d)
Intra uterine devices
Intra uterine insemination
Inter uterine insemination
Intra cytoplasmic sperm injection
NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
■ Directions (Q. No. 73-89) In each of the following
questions, a statement of Assertion (A) is given followed
by corresponding statement of Reason (R). Of the
statements, mark the correct answer as
(a) If both A and R are true and R is the correct
explanation of A
(b) If both A and R are true, but R is not the correct
explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true
73 Assertion (A) A person should be considered
74
75
76
77
reproductively healthy, if he has healthy reproductive
organs, but is emotionally imbalanced.
Reason (R) It is significant to maintain reproductive
health of people and society.
Assertion (A) Family planning is an action plan to
attain reproductive health.
Reason (R) Some additional improved programmes
covering reproduction related areas are currently in
operation under the Reproductive and child
Healthcare Programmes.
Assertion (A) Reproductive and Child Healthcare
Programme is for reproduction related areas.
Reason (R) It deals with creating awareness among
various reproduction related aspects.
Assertion (A) Amniocentesis is often misused.
Reason (R) It is meant for determining the genetic
disorders in the foetus, but it is being used to
determine the sex of the foetus, leading to increase in
the female foeticide.
Assertion (A) Rapid decline in death rate, MMR and
IMR have lead to staggering rise in population.
Reason (R) Such an alarming growth rate has lead to
an absolute scarcity of even the most basic
requirements, i.e. food and shelter.
78 Assertion (A) Overpopulation has become a serious
problem in the developing countries.
Reason (R) Developing countries show
characteristics such as high fertility, low or rapidly
falling mortality rate, rapid population growth and a
very young age distribution.
79 Assertion (A) Family planning is done by using
contraceptive methods.
Reason (R) Natural contraceptive methods include
condoms, diaphragms, etc., while barrier methods
include periodic abstinence, lactational amenorrhea,
etc.
80 Assertion (A) Reusable contraceptives are safe
methods of contraceptions.
Reason (R) Diaphragms, cervical caps and vaults are
barrier methods which prevent conceptions by
blocking entry of sperms through cervix. They are
reusable.
81 Assertion (A) Contraceptives are methods to prevent
unwanted pregnancies.
Reason (R) Unwanted pregnancies can only be
prevented by using oral contraceptives.
82 Assertion (A) There is chance of fertilisation during
10th-17th days of menstrual cycle.
Reason (R) Ovulation can be expected during these
days.
83 Assertion (A) Barrier methods prevent conception.
Reason (R) These prevent the physical meeting of
sperm and ova.
84 Assertion (A) Sterilisation is a surgical method of
contraception.
Reason (R) It blocks gamete transport and thereby
prevents conception.
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Master The NCERT > BIOLOGY (Vol-II )
80
85 Assertion (A) Use of condoms is a safeguard against
86
87
88
89
AIDS and sexual diseases besides preventing
pregnancy.
Reason (R) Certain contraceptives are planted under
the skin of the upper arm to prevent pregnancy.
Assertion (A) Syphilis, chlamydiasis, Genital herpes
and trichomoniasis are STIs.
Reason (R) Their incidences are reportedly high in
people belonging 15-24 years age groups.
Assertion (A) Both male and female can be infertile.
Reason (R) Infertile couples can have children with
the help of ARTs.
Assertion (A) In zygote intra Fallopian transfer, the
zygote is transferred to the Fallopian tubes of the
female.
Reason (R) ZIFT is an in vivo fertilisation method.
Assertion (A) Artificial insemination is method of
introduction of semen inside the female.
Reason (R) This technique is used in those cases
where males have low sperm count.
II. Statement Based Questions
90 Select the statement which is not a cause of
population growth.
(a)
(b)
(c)
(d)
Decline in death rate
Rapid increase in MMR and IMR
Rapid decline in MMR and IMR
Increase in the number of people in the reproductive
age group
91 Identify the incorrect statement(s) from those given
below.
(a) RCH programmes created awareness among people
about various reproduction related aspects
(b) Sexually transmitted diseases can be avoided by
educating people with proper information about
reproduction, adolescence and related changes, etc.
(c) Ultrasounds have been banned as it was used for foetal
sex-determination based on chromosomal studies
(d) All of the above
92 Select the correct statement(s) which includes the
steps implemented by government to control the
increasing population.
(a) Increasing the price of contraceptives so they are
available to all
(b) Advertising the benefits of small family, slogans like,
‘hum do hamare do’, etc.
(c) Raising the marriageable age, females 18 years, males
21 years
(d) Both (b) and (c)
93 Which one of the following statement is incorrect in
the context of amniocentesis?
(a)
(b)
(c)
(d)
NEET 2016
It is used for prenatal sex-determination
It can be used for detection of Down’s syndrome
It can be used for detection of cleft palate
It is usually done when a woman in between
14-16 weeks pregnant
94 Which statement is correct for natural methods of
contraception?
(a)
(b)
(c)
(d)
They increase phagocytosis of sperms
They employ barriers to prevent fertilisation
They are surgical methods and are terminal methods
They are natural ways of avoiding chances of
fertilisation
95 Diaphragms are the contraceptive devices, used by
the females.
I. They are introduced into the uterus.
II. They are placed to cover the cervical region.
III. They act as physical barriers to the sperm entry.
IV. They act as spermicidal agents.
Choose the correct statements.
(a)
(b)
(c)
(d)
I and II
I and III
II and III
III and IV
96 Consider the following statements for IUD and
choose the correct option.
(a) Increases phagocytosis of sperms
(b) Releases Cu 2+ ions, suppresses the sperm motility
(c) Reduces the fertilising capacity of sperms
(d) All of the above
97 Find out the incorrect statement for IUD.
(a) They can be self-inserted
(b) They are inserted by expert nurses/doctors
(c) They may be non-medicated IUDs, copper releasing
IUDs or hormone releasing IUDs
(d) They are intrauterine devices
98 Which of the following is a correct statement?
(a) IUDs once inserted need not be replaced
(b) Jellies and cream enable sperms to reach towards ovum
speedly
(c) IUDs increase phagocytosis of sperms in the uterus
(d) Pills suppress gametogenesis in males
99 Which of the following is incorrect regarding
vasectomy?
NEET 2016
(a) No sperm occurs in seminal fluid
(b) No sperm occurs in epididymis
(c) Vasa deferentia is cut and tied
(d) Irreversible sterility
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CHAPTER 04 > Reproductive Health
100 Identify the false statement from the below
statements.
(a) Genital herpes and hepatitis-B are sexually transmitted
diseases caused by virus
(b) Syphilis is an STD caused by bacterium Treponema
pallidum
(c) In India, there is rapid decline in infant mortality rate
and MMR
(d) Genital warts is a sexually transmitted disease caused
by herpes virus
101 Identify the correct statements.
(a) Infertility is the inability to produce viable offspring
due to the defects in the female or male partner
(b) Lactation have no role in preventing conception
(c) Abstaining from coitus from day 10-17 of menstrual
cycle when ovulation is expected constitutes natural
method of contraception
(d) Both (a) and (c)
102 Which of the following statements is incorrect about
ZIFT?
(a)
(b)
(c)
(d)
Zygote in the Fallopian transfer
Type of IVF
Embryo with more than 8 blastomeres are used
Zygote or embryo with up to 8 blastomeres are used
103 Which statement is false for GIFT?
(a)
(b)
(c)
(d)
It is Gamete Intra Fallopian Transfer
Ovum is transferred into the oviduct
Zygote is transferred into Fallopian tube
Used when the receptive is sterile
104 Choose the correct matched statements from the
following.
I. IUT – Embryo is transferred into the uterus after in
vitro fertilisation.
II. GIFT – Gametes are collected and injected in the
Fallopian tube.
III. AI – Taking semen from donor and transferring it into
female genital tract.
IV. ZIFT – Zygote inserted into the Fallopian tube.
V. ICSI – One sperm transferred into the ovum.
(a)
(b)
(c)
(d)
I, II and III
II, III and IV
III, IV and V
I, II, III, IV and V
105 Choose the WHOs statement about reproductive
health.
I. Healthy reproductive organs with normal functions.
II. Total well-being of physical, emotional, behavioural
and social aspects.
III. Free of all STD.
(a)
(b)
(c)
(d)
I and II
I and III
II and III
Only II
81
106 What is true for an ideal contraceptive?
I. It should be user-friendly.
II. It should be easily available.
III. It should be effective and reversible with least side
effects.
IV. It should be interfering in coitus.
V. It should be expensive and effective.
Choose the correct option.
(a) I, IV and III
(c) I, II and III
(b) I, IV and V
(d) II, IV and V
107 Which of the following statements are correctly
associated with Saheli?
I. It is a ‘once a week’ pill with very few side effects.
II. This contraceptive was a developed at CDRI
Lucknow.
III. Saheli is an oral pill containing a steroidal preparation.
IV. This oral contraceptive is known to cause multiple side
effects in women and has low contraceptive value.
(a) III and IV
(c) I, II and III
(b) I and II
(d) All of these
108 Identify the correct statements about lactational
amenorrhea.
I. Ovulation does not occur during the lactational period.
II. Chances of the failure of contraception are almost nil
up to six months following parturition.
III. Side effects are almost nil.
IV. It is a natural method of contraception.
V. It increases phagocytosis of sperms.
(a) II, III, IV and V
(c) I, III, IV and V
(b) All except V
(d) All of these
109 Which statements show the correct purpose of
contraceptive pills?
I. They inhibit ovulation and implantation.
II. They alter the quality of cervical mucus to prevent or
retard the entry of sperms.
III. They prevent the ejaculated semen from entering the
female vagina.
IV. They inhibit spermatogenesis.
(a) I, II and IV
(c) I and II
(b) I, II and III
(d) I, II, III and IV
110 Identify the false statements regarding the techniques
of contraception.
I. There are many side effects of tubectomy and
vasectomy.
II. Purpose of tubectomy is to prevent egg formation.
III. The most important component of the oral
contraceptive pills is progesterone.
IV. Contraceptive oral pills help in birth control by
preventing ovulation.
(a) I, II and III
(c) III, IV and II
(b) I and II
(d) II and IV
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Master The NCERT > BIOLOGY (Vol-II )
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111 Find out the correct statements about tubectomy.
I. The failure rate of this approach is almost zero per cent.
II. It is also known as tubal ligation.
III. It is more difficult than vasectomy and is even more
difficult to reverse.
(a) I and II
(c) I and III
(b) II and III
(d) All of these
112 Consider the following statements and choose the
correct statements.
I. Numerous children have been produced by in vitro
fertilisation but with some abnormalities.
II. Chances of conception are nil until mother breastfeeds
the child for two years.
III. Birth control pills are likely to cause cardiovascular
problems due to oestrogen present in them.
IV. Emergency contraceptive pills may be taken within
72 hours of coitus to prevent conception.
(a) III and IV (b) I and III (c) I and II
(d) II and III
113 Which of the following given statements are not
correct?
I. A statutory ban has been implemented on
amniocentesis because of its regular misuse.
II. Surgical methods are also called sterilisation as they
block the release of gametes into secretions.
III. All sexually transmitted diseases are completely
curable.
IV. MTPs are relatively safe up to 20 weeks of pregnancy.
(a) I and III
(c) II and III
(b) III and IV
(d) I and II
114 Which of the following statements are false?
I. Abortions could happen spontaneously too.
II. Oral pills are very popular contraceptives among the
rural women.
III. Removal of gonads can be considered as a
contraceptive option.
IV. Sex education is necessary in schools.
V. Amniocentesis for sex-determination is banned in our
country.
Correct option is
(a) I, II and III
(c) III, IV and V
(b) II, III and IV
(d) II and III
115 To avoid transmission of STDs.
I. Avoid sex with multiple partners.
II. Always have unprotected sex.
III. Use condoms during coitus.
IV. Avoid sex with unknown partners.
V. Avoid sharing of needles.
Choose the correct option.
(a) I and II
(c) I and III
(b) II, III and IV
(d) I, III, IV and V
116 STDs lead to the
I. minor complications like itching, fluid discharge,
slight pain, swellings.
II. major complications like pelvic inflammatory diseases
ectopic pregnancies.
III. problems like infertility, abortions.
IV. cancer of the reproductive tract.
Choose the correct option.
(a) I, II and IV
(c) I, III and IV
(b) I, II and III
(d) All of these
117 Which of the following statements are correct?
I. MTPs are generally advised during first trimester.
II. MTP (Amendment) Act, 2017 was enacted by the
government of India to reduce illegal abortions.
III. Government of India legalised MTP in 1971.
IV. MTP during the second trimester can be done in case
where the child after birth would suffer from some
physical or mental abnormalities.
(a) I, II, III, IV and V
(c) I, III, IV, V and VI
(b) I, II, III, V and VI
(d) All of these
III. Matching Type Questions
118 Match the following columns.
Column I
Column II
A. Amniocentesis
1. Venereal disease
B. Reproductive tract
infections
2. Deformed joints and paralysis
C. Syphilis
3. Foetal sex-determination
D. Gonorrhoea
4. Baby of infected person born
blind
Codes
A
(a) 3
(c) 2
B
1
3
C
2
1
D
4
4
A
(b) 1
(d) 4
B
2
3
C
3
2
D
4
1
119 Match the following columns.
Column I
Column II
A. Saheli
1. Intra uterine device
B. Diaphragms
2. Prevent ovulation and implantation
C. Spermicides
3. Prevent sperms from reaching the
cervix
D. Lippes loop
4. Sperm killing agent
Codes
A
(a) 1
(b) 2
(c) 2
(d) 4
B
2
3
3
3
C
4
4
1
2
D
3
1
4
1
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CHAPTER 04 > Reproductive Health
83
120 Match the following columns.
Column I
(Infertility conditions)
Column II
(Features)
A. Oligospermia
1.
Ovarian cyst formation
B. Azospermia
2.
Inflammation of ovary due to
infection
C. Cryptorchidism
3.
Decreased sperm count
D. Oophorocystosis
4.
Absence of living sperms
E. Oophoritis
5.
Non-descendence of testes
from abdominal cavity to
scrotum
Codes
A
(a) 3
(b) 1
(c) 5
(d) 4
B
4
2
4
1
C
5
3
3
2
D
1
4
2
5
Column I
(STDs)
Column II
(Causal agents)
A.
Chlamydiasis
1.
Chlamydia trachomatis
B.
Chancroid
2.
Haemophilus ducreyi
C.
Trichomoniasis
3.
Trichomonas vaginalis
D.
Genital herpes
4.
Herpes simplex virus
B
3
2
C
2
3
D
4
4
A
(b) 4
(d) 1
Column I
(STDs)
B
1
2
C
3
4
D
2
3
D
2
4
2
3
124 Match the following columns.
Column I
(Contraceptive methods)
Column II
(Categories)
A. Periodic abstinence
1.
Natural methods
B. Vasectomy
2.
Barrier methods
C. Coitus interruptus
3.
Surgical methods
1. Zidovudine drug
2. Cryosurgery
C. Syphilis
3. Penicillin and tetracycline
D. Enterobiasis
4. Antihelminthic tablets
E.
Lactational amenorrhea
F.
Cervical caps
Codes
A
(a) 1
(b) 1
(c) 2
(d) 1
B
1
3
1
3
C
2
2
2
1
D
3
1
1
2
E
2
3
3
1
F
3
2
3
2
Column I
(Names of IUDs)
Column II
(Examples of IUDs)
A. Non-medicated IUD
1. Progestasert and LNG-20
B. Copper releasing IUD
2. Lippes loop
C. Hormone releasing IUD 3. Cu-T, Cu-7 and Multiload-375
Codes
A
(a) 3
(b) 1
(c) 2
(d) 2
Column II
(Treatments)
B. Genital warts
Codes
A
(a) 4
(c) 2
C
1
1
4
2
125 Match the following columns.
122 Match the following columns.
A. AIDS
B
4
3
1
1
D. IUDs
E
2
5
1
3
121 Match the following columns.
Codes
A
(a) 1
(c) 1
Codes
A
(a) 3
(b) 2
(c) 3
(d) 4
B
2
2
3
1
C
1
3
1
3
126 Match the following columns.
Column I
B
3
4
C
2
1
D
1
3
A
(b) 1
(d) 1
B
3
2
C
4
3
D
2
4
A.
Government of India
legalised MTP in
1.
1951
B.
Family planning introduced 2.
in India
1971
C.
Nirodh
3.
Barrier method
D.
Mala-D and Mala-N
4.
Hormonal method
123 Given below are the four methods and their modes of
action in achieving contraception. Select their correct
matching from the four options that follows.
Column I
(Birth control measures)
Column II
(Modes of action)
A. Pill
1. Prevents sperms reaching cervix
B. Condom
2. Prevents implantation
C. Vasectomy
3. Prevents ovulation
D. Copper-T
4. Semen contains no sperms
Column II
Codes
A
(a) 1
(b) 2
(c) 4
(d) 1
B
2
1
3
4
C
3
3
2
3
D
4
4
1
2
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84
Column I
127 Match the following columns.
Column I
Column II
A.
Collected gametes are made to
form the zygote in the
laboratory.
1.
In vivo fertilisation
B.
Zygote or Early embryo with up
to 8 blastomeres is transferred
into the oviduct.
2.
IUT
C.
Zygote with more than 8
blastomeres, is transferred into
the uterus.
3.
ZIFT
D.
Fusion of the gametes in the
female reproductive tract.
4.
IVF
Codes
A
(a) 4
(b) 3
(b) 4
(d) 2
B
3
1
2
1
C
2
4
3
3
Column II
A.
Gonorrhoea
1.
HIV
B.
Syphilis
2.
Neisseria
C.
Genital warts
3.
Treponema
4.
Human papilloma virus
D. AIDS
Codes
A
(a) 2
(c) 4
B
3
2
C
4
3
D
1
1
A
(b) 3
(d) 4
B
4
3
C
1
2
D
2
1
129 Match Column I with Column II and select the correct
D
1
2
1
4
128 Match the following sexually transmitted diseases
(Column I) with their causative agent (Column II) and
select the correct option.
NEET 2017
option from the given codes.
Column I
(Diseases)
Column II
(Diagnostic tests)
A.
Syphilis
B.
Genital herpes
2.
VDRL Test
C.
AIDS
3.
Urine Test
D.
Gonorrhoea
4.
ELISA
Codes
A
(a) 1
(c) 4
B
2
3
C
3
2
1.
D
4
1
PCR Test
A
(b) 2
(d) 3
B
1
4
C
4
1
D
3
2
NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
130 A national level approach to build up a reproductively
healthy society was taken up in our country in
(a) 1950s
(c) 1980s
(b) 1960s
(d) 1990s
131 Increased IMR and decreased MMR in a population
will
(a) cause rapid increase in growth rate
(b) result in decline in growth rate
(c) not cause significant change in growth rate
(d) result in an explosive population
132 Intensely lactating mothers do not generally conceive
due to the
(a) suppression of gonadotropins
(b) hypersecretion of gonadotropins
(c) suppression of gametic transport
(d) suppression of fertilisation
133 Condoms are one of the most popular contraceptives
because of the following reasons.
(a) These are effective barriers for insemination
(b) They do not interfere with coital act
(c) These help in reducing the risk of STDs
(d) All of the above
134 Diaphragms are contraceptive devices used by the
females. Choose the correct option from the
statements given below.
I. They are introduced into the uterus.
II. They are placed to cover the cervical region.
III. They act as physical barriers for sperm entry.
IV. They act as spermicidal agents.
(a) I and II
(b) I and III (c) II and III
(d) III and IV
135 Choose the right one among the statements given
below.
NEET (Odisha) 2019
(a) IUDs are generally inserted by the user herself
(b) IUDs increase phagocytosis reaction in the uterus
(c) IUDs suppress gametogenesis
(d) IUDs once inserted need not be replaced
136 Emergency contraceptives are effective if used within
72 hrs of
(a) coitus
(c) menstruation
(b) ovulation
(d) implantation
137 The correct surgical procedure as a contraceptive
method is
(a) ovariectomy
(c) vasectomy
(b) hysterectomy
(d) castration
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CHAPTER 04 > Reproductive Health
85
141 Sterilisation techniques are generally foolproof
138 From the sexually transmitted diseases mentioned
methods of contraception with least side effects.
Yet, this is the last option for the couples because
I. it is almost irreversible.
II. of the misconception that it will reduce sexual
urge/drive.
III. it is a surgical procedure.
IV. of lack of sufficient facilities in many parts of the
country.
Choose the correct option.
below, identify the one which does not specifically
affect the sex organs.
(a) Syphilis
(b) AIDS
(c) Gonorrhoea
(d) Genital warts
139 Choose the correct statement regarding the ZIFT
procedure.
(a) Ova collected from a female donor are transferred to the
Fallopian tube to facilitate zygote formation
(b) Zygote is collected from a female donor and transferred
to the Fallopian tube
(c) Zygote is collected from a female donor and transferred
to the uterus
(d) Ova collected from a female donor and transferred to
the uterus
(a) I and III
(c) II and IV
(b) II and III
(d) I, II, III and IV
142 Following statements are given regarding MTP.
assisted by reproductive technology is called
Choose the correct option given below.
I. MTPs are generally advised during first trimester.
II. MTPs are used as a contraceptive method.
III. MTPs are always surgical.
IV. MTPs require the assistance of qualified medical
personnel.
(a) GIFT
(c) ICSI
Codes
(a) I and III
140 The method of directly injecting a sperm into ovum is
(b) ZIFT
(d) ET
(b) II and III (c) I and IV
(d) I and II
Answers
‡ Mastering NCERT with MCQs
1 (d)
2 (a)
3 (a)
4 (a)
5 (a)
6 (d)
7 (d)
8 (b)
9 (c)
10 (d)
11 (d)
12 (c)
13 (b)
14 (b)
15 (b)
16 (b)
17 (a)
18 (c)
19 (c)
20 (b)
21 (c)
22 (b)
23 (d)
24 (d)
25 (b)
26 (b)
27 (c)
28 (b)
29 (b)
30 (b)
31 (c)
32 (b)
33 (a)
34 (c)
35 (a)
36 (a)
37 (a)
38 (c)
39 (d)
40 (a)
41 (b)
42 (c)
43 (c)
44 (d)
45 (a)
46 (d)
47 (a)
48 (a)
49 (b)
50 (c)
51 (d)
52 (b)
53 (c)
54 (c)
55 (c)
56 (d)
57 (d)
58 (d)
59 (b)
60 (a)
61 (d)
62 (b)
63 (a)
64 (a)
65 (d)
66 (d)
67 (d)
68 (b)
69 (c)
70 (c)
71 (a)
72 (b)
77 (b)
78 (b)
79 (c)
80 (a)
81 (c)
82 (a)
83 (a)
84 (a)
85 (b)
86 (b)
87 (b)
92 (d)
93 (c)
94 (d)
95 (c)
96 (d)
97 (a)
98 (c)
99 (b) 100 (d) 101 (d) 102 (c)
‡ NEET Special Types Questions
73 (d)
88 (c)
103 (c)
74 (b)
75 (a)
76 (a)
89 (a)
90 (b)
91 (c)
104 (d) 105 (d) 106 (c)
118 (a) 119 (b) 120 (a) 121 (c)
107 (b) 108 (b) 109 (c)
122 (d) 123 (c)
110 (b) 111 (d) 112 (a) 113 (b) 114 (d) 115 (d) 116 (d) 117 (d)
124 (d) 125 (c)
126 (b) 127 (a) 128 (a) 129 (b)
‡ NCERT Exemplar Questions
130 (a) 131 (c)
132 (a) 133 (d) 134 (c)
135 (b) 136 (a) 137 (c)
138 (b) 139 (b) 140 (c)
141 (a) 142 (c)
Answers & Explanations
1 (d) The term ‘reproductive health’ simply refers to healthy
5 (a) Amniocentesis is a foetal sex-determination test based on
reproductive organs with normal functions. However, in
broader perspectives it includes a total well-being in all
aspects of reproduction, i.e. emotional, behavioural, physical
and social.
4 (a) Reproductive health can be improved by educating and
creating awareness among the people about various aspects
of reproductive health.
the analysis of chromosomal pattern using the amniotic fluid
surrounding the developing embryo.
6 (d) Jaundice is a condition not based on chromosomal
pattern, hence it cannot be detected by amniocentesis. It is a
disease related to liver dysfunctioning.
7 (d) There are some indicators of improved reproductive
health of the society. These include better awareness about
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14
15
18
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20
Answers & Explanations
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sex related problems, pre-natal care of the mother,
medically assisted deliveries, post-natal care of the
mother and infant, decrease maternal and infant
mortality, small families, better detection and cure of
Sexually Transmitted Diseases (STDs), increased
medical facilities for sex related problems, etc.
(c) An ideal contraceptive should be user-friendly,
easily available, effective and reversible with no or least
side effects. It also should in no way interfere with the
sexual drive, desire and/or the sexual act of the user.
(b) One of the legal method of birth control is periodic
abstinence in which couples abstain from coitus from
day 10-17 of the menstrual cycle. For other options,
Abortion by taking medicine is not a legal method.
A day break coitus may increase the chances of
contraception. A premature ejaculation during coitus
will result in fertilisation.
(b) Periodic abstinence is avoiding sex during ovulatory
phase, i.e. from day 10th-17th of the menstrual cycle. It
is also known rhythm method. It is done as a
contraceptive method because chances of fertilisation
are very high during this period.
(c) Lactational amenorrhea is the absence of
menstruation during lactation. It is a natural
contraception method in which the chances of
conception are almost nil in a breastfeeding mother due
to the absence of ovulation. This method is effective
only up to a maximum period of six months after
childbirth.
(c) Condoms or Femidoms are barriers made up of thin
rubber/ latex sheath that are used to cover the penis in
the male or vagina and cervix in the female, just before
coitus. So, that the ejaculated semen would not enter
into the female reproductive tract.
(b) Diaphragms, cervical caps and vaults are barrier
method used by females only. These are made up of
rubber that are inserted into the female reproductive
tract to cover the cervix during coitus. They prevent
conception by blocking the entry of sperms through the
cervix. They are reusable.
(c) Spermicidal creams contain chemicals, which kill
the sperms. If they are used along with the barrier
contraceptive methods, then these increases
contraceptive efficiency.
(b) Depo-provera is an injectible form of the hormone
based contraception. These are progesterone derivative
injections, which are taken every two-three months.
These release hormone slowly and prevent ovulation.
(b) Progestasert and LNG-20 are hormone releasing
Intra Uterine Devices (IUDs). These devices release
small quantities of hormone which suppresses
endometrial changes, ovulation and causes insufficient
luteal activity.
(c) The copper releasing IUDs, release Cu + ions which
suppress the sperm motility and the fertilising capacity
of sperms.
30 (b) The females wanting to delay pregnancy or space
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34
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38
39
40
42
children should use IUDs, i.e. Intra Uterine Devices.
These provide long term but reversible contraception.
Other options like tubectomy is an irreversible method
and femidoms, vaults and caps are barrier methods
which do not provide long term contraception.
(c) Oral contraceptives have hormonal preparation of
small doses of either progesterone or
progesterone-oestrogen combination in the form of
tablets. These are used by females.
(b) Pills have to be taken daily for 21 days starting
within the first 5 days of menstrual cycle. After a gap of
7 days (during which menstruation occurs) these has to
be repeated in the same pattern till the female desires to
prevent conception.
(c) The oral contraceptive ‘Saheli’ blocks oestrogen
receptors in the uterus preventing eggs from getting
implanted. It is a type of mini pill that contains a
non-steroidal preparation centchroman. It is taken once
in a week after an initial intake of twice a week dose for
3 months. This non-hormonal preparation contains
progestin only and no oestrogen.
(a) Implants, i.e. six matchstick-sized capsules
containing steroids are inserted under the skin of the inner
arm above the elbow. These steroid capsules slowly
release the synthetic progesterone or
progesterone-oestrogen combination for about 5 years.
(c) Option (c) is correct. As hormonal implants and oral
contraceptives have the same combination of oestrogen
and progesterone hormones. Their mode of working is
same but the site of implantation is different, i.e.
implants are placed under the skin, while oral
contraceptives are orally consumed. The duration of
their effective period also varies since implants have
long lasting effects compared to pills.
(d) Lactational amenorrhea, pills and emergency
contraceptives provide contraception due to the role of
hormones. In lactational amenorrhea, high prolactin
level during active lactation period decreases the
gonadotropin level in the blood.
Pills usually contain progesterone or
progesterone-oestrogen hormonal combinations which
prevent ovulation. Emergency contraceptives also
contain progesterone and oestradiol preparations.
Other contraceptive methods include barrier method,
represent a physical method of contraception. Also,
copper-T (Cu-T) acts by releasing copper and not any
hormone.
(a) Tubectomy is a sterilisation method of
contraception. During this procedure, a small part of the
Fallopian tube in females is removed or tied up and
blocked to restrict the entry of sperms reaching the ova.
It is a permanent birth control method.
(c) Option (c) does not give the defined action of
contraceptive. It can be corrected as
Vasectomy prevents transport of sperms and not its
production, i.e. spermatogenesis.
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50
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In this method of contraception, small part of vas
deferens is removed or tied up through a small incision
on the scrotum.
(d) Sterilisation techniques include vasectomy and
tubectomy. These are very reliable methods of birth
control, because their approximate failure rate is less
than 1%.
(a) MTP (Medical Termination of Pregnancy) is
considered as safe until Ist trimester (12 weeks) of the
pregnancy. It becomes more risky after the Ist trimester
period of pregnancy, as the foetus becomes intimately
associated with the maternal tissue.
(c) The other name for Sexually Transmitted Diseases
(STDs) are Venereal Diseases (VDs) or Reproductive
Tract Infections (RTIs). These diseases or infections
are transmitted through sexual intercourse with
infected persons.
(d) Mode of infection of AIDS and hepatitis-B are
same. These diseases spread from an infected person to
healthy person through sharing of needles, transfusion
of blood and from infected mother to child. Both
diseases are also incurable.
(b) Genital herpes is a sexually transmitted disease
which is not completely curable. It is caused by type-II
herpes simplex virus. Treatment is available for herpes
symptoms, but the virus is unaffected and remains in the
body, thus can becomes active again.
(c) AIDS and Hepatitis-B are sexually transmitted
diseases which do not specifically affect reproductive
organs. AIDS affects the overall immune system of the
individual and hepatitis-B affects the liver. These are
called STDs because they spread through via body
fluids unsafe sex or use of needles, etc.
(c) Incidence of STIs or STDs are very high among
persons in the age group of 15-24 years. This is due to
the fact that young people
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Have multiple sex partners.
Engage in unprotected sex.
Use drugs and alcohol at high rate.
Engage in high risk behaviours, while under the
influence of drugs and /or alcohol.
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65
66
68
69
70
73
74
58 (d) A large number of couples are unable to produce
children inspite of unprotected sex, i.e. are infertile. The
reasons for this could be physical, congenital diseases,
drugs, immunological or even psychological defect.
59 (b) IVF is an Assisted Reproductive Technology (ART)
that involves transfer of zygote into Fallopian tube. In
vitro fertilisation is a process in which an egg is
fertilised by sperm outside the woman’s womb and the
zygote up to 8-celled stage is implanted into the
Fallopian tube. IVF is a major treatment for infertility.
60 (a) In ZIFT (Zygote Intra Fallopian Transfer), the
zygote up to 8-celled stage is transferred to Fallopian
tube, rest of the development takes place as that of the
natural zygote in the uterus.
61 (d) The test tube baby programme is a method involving
In Vitro Fertilisation (IVF). It employs the technique of
75
Zygote Intra Fallopian Transfer (ZIFT) as only in this
technique, fertilisation allowed to occur outside the
body in laboratory.
(a) If an embryo containing more than 8 blastomeres
(cells) is transferred into uterus of female’s body then, it
is called as IUT (Intra Uterine Transfer). It is also a
method of IVF.
(d) Difference between ZIFT and IUT lies in the
number of the cells. As in ZIFT, the embryo or zygote
transfer is done up to 8 blastomere stage and in IUT, the
embryo transfer is done when embryo is above 8
blastomere stage.
(d) IVF (In Vitro Fertilisation), AI (Artificial
Insemination) and in vivo fertilisation are all procedures
of ART (Assisted Reproductive Technologies). When
the correction of infertility related disorders is not
possible couples are advised to have children through
these processes.
(b) The full form of GIFT is Gamete Intra Fallopian
Transfer. It is a technique in which ovum is transferred
into the Fallopian tube of another female, who cannot
produce one, but can provide suitable environment for
fertilisation and further development.
(c) ICSI (Intra Cytoplasmic Sperm Injection) is a
technique in which a sperm is directly injected into the
ovum to form the zygote and further into an embryo in
the laboratory (in vitro). This embryo is then transferred
into the uterus or Fallopian tube as required.
(c) Artificial insemination is commonly used in cases,
where male partners are unable to inseminate the female
due to very low sperm counts in the ejaculate. In this
method, the semen is collected either from husband or a
healthy donor and then artificially introduced into the
vagina or into the uterus of the female.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
According to the World Health Organisation (WHO), a
person is reproductively healthy when he is physically,
emotionally, behaviourally and socially healthy, i.e.
overall healthy.
(b) Both Assertion and Reason are correct, but Reason
is not the correct explanation of Assertion. The correct
explanation is as follows
Family planning is an action plan mediated by RCH (in
1952) to achieve population stabilisation goals and also
promotes reproductive health, reduces maternal, infant
and child mortality. This was achieved by delaying the
childbirth till mother is over 20 yrs of age, spacing
between children and limited size of family.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
Reproductive and Child Healthcare (RCH) programmes
were initiated in 1951 by government of India to deal
with reproduction related areas. These programmes are
aimed at creating awareness among people about
various aspects such as sex education, reproduction and
STDs, knowledge of birth control and pregnancy, sex
abuse, etc.
Answers & Explanations
87
CHAPTER 04 > Reproductive Health
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76 (a) Both Assertion and Reason are correct and Reason
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Answers & Explanations
80
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82
is the correct explanation of Assertion.
Amniocentesis, a medical procedure used in prenatal
diagnosis of chromosomal abnormalities and foetal
infections is being misused for determining the sex of
unborn foetus. If the sex comes is revealed as female,
it is followed by medical termination of foetus. This
has lead to an increase in the number of female
foeticide in our country and is major reason for a ban
being implemented on it.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion. The correct
explanation is as follows
Rapid decline in death rate, MMR (Maternal Mortality
Rate) and IMR (Infant Mortality Rate) have all
happened due to significant improvement in quality of
life, increased medical facilities, awareness about
reproduction related facts such as pre and post- natal
care of mother’s vaccination of children, etc., supported
by better living conditions.
As a result, there has been a staggering rise in
population.
(b) Both Assertion and Reason are correct, but Reason is
not the correct explanation of Assertion. The correct
explanation is as follows
Overpopulation has become a serious problem in the
developing countries because of the improved medical
facilities and quality of life.
(c) Assertion is true, but Reason is false. Reason can be
corrected as
Contraceptives help in family planning by inhibiting
fertilisation of gametes. Natural methods work on the
principle of avoiding chances of ovum and sperms
meeting, e.g. periodic abstinence, lactational
amenorrhea.
In barrier methods, ovum and sperm are prevented from
physically meeting with the help of barrier, e.g.
condoms, cervical caps, diaphragms, etc.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
Reusable contraceptives are safe methods because they
prevent exchange of body fluids during intercourse by
preventing the entry of sperms into vagina and uterus.
These include diaphragms, cervical caps, vaults, etc.,
and are inserted before intercourse and can be reused.
(c) Assertion is true, but Reason is false. Reason can be
corrected as
Contraceptive can be broadly grouped into natural,
barrier, IUDs, oral contraceptives, injectables, implants
and surgical methods. These all methods are used to
prevent unwanted pregnancies.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
There is a chance of fertilisation during 10-17 days of
menstruation cycle because most in females, ovulation
is expected to occur during these days. Thus, the couple
paracticing periodic abstinence refrains from sexual
intercourse during this period.
83 (a) Both Assertion and Reason are correct and Reason
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is the correct explanation of Assertion.
Barrier methods prevent conception because they do not
allow the ovum and sperms to physically meet, thereby
preventing fertilisation, e.g. condoms, diaphragms, etc.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
Sterilisation is a surgical method of contraception as it
blocks the transport of gametes and hence prevent
fertilisation. The process is called as vasectomy in
males and tubectomy in females.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion. The correct
explanation is as follows
Condoms act as a barrier that prevents the male
ejaculate from entering female body and thus avoids
conception and also prevents the transmission of STDs
such as AIDS.
In females, implants are placed under the skin as the
method of contraceptive.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion. The correct
explanation is as follows
Syphilis, chlamydiasis, genital herpes and
trichomoniasis are STIs because they spread from
infected person to other through sexual contact or
unsafe, unhygienic sexual practices.
(b) Both Assertion and Reason are correct, but Reason
is not the correct explanation of Assertion.
Both male and female can be infertile, i.e. unable to
conceive or bear children. This can happen because of
various reasons which can be physical congenital
immunological or even psychological disorders, e.g.
cryptorchidism, hyperthermia STDs, alcoholism (in
males), PCOs, blocked Fallopian tube, irregular
menstrual cycle, etc (in females).
(c) Assertion is true, but Reason is false. Reason can be
corrected as
ZIFT is an in vitro fertilisation method, in which zygote
is transferred into Fallopian tube of the female.
(b) Statements in option (b) is not a cause for population
growth. As a rapid increase in IMR and MMR
contributes to population growth.
Other options are correct.
(c) Statement in option (c) represents the incorrect
statement and can be corrected as
Amniocentesis was banned by government due to its
misuse in detection of sex of child based on
chromosomal studies. This information lead to an
increase in female foeticides.
Rest of the statements are correct.
(c) Statement in option (c) represents the incorrect
statement and can be corrected as
Cleft palate is a developmental abnormality which may
occur in the developing foetus. So, it can be detected by
sonography, not by amniocentesis.
Rest of the statements are correct.
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CHAPTER 04 > Reproductive Health
94 (d) Statement in option (d) is correct about natural method
106 (c) Statements I, II and III are characteristics of an
of contraception.
Natural methods of contraception include lactational
amenorrhea, coitus interruptus and periodic abstinence.
These methods work on the natural ways to avoiding
chances of ovum and sperm meeting.
While other statements are related to barrier methods.
97 (a) The statement in option (a) is incorrect about IUD. It
can be corrected as
Intra Uterine Devices (IUDs) are popular methods of
contraception. These devices are inserted by doctors or
expert nurses in the uterus through vagina.
Rest other statements are correct for IUDs.
98 (c) Statements in option (c) is correct.
Other statements are incorrect and can be corrected as
ideal contraceptive.
An ideal contraceptive should be user friendly, easily
available, effective and reversible with least
side-effects. It also should not interfere with the
sexual drive, desire and sexual act of the user.
107 (b) Statements I and II are correct for Saheli pills.
‘Saheli’ a new oral contraceptive for females was
developed at CDRI in Lucknow. It is once in a week
pill with non-steroidal preparation. It has few side
effects and a high contraceptive value.
108 (b) All statements are correct except (V). It can be
corrected as
Lactational amenorrhea is based on the fact that
ovulation does not occur during lactation, so chances
of conception are almost nil, up to six months
following parturition. It is a natural method of
contraception associated with the females, whereas
phagocytosis of sperms is associated with males.
109 (c) Statements I and II show the correct purpose of
contraceptive pills. Statements III and IV are incorrect
and can be corrected
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IUDs can be removed as these are a reversible
contraception method.
Jellies are cream are spermicidal and immobilise the
sperms.
Pills inhibits ovulation and implantation in females.
99 (b) Statement in option (b) gives incorrect information
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regarding vasectomy.It can be corrected as
Sperms are produced by testes in the male reproduction
system and sent to the epididymis by vasa efferentia and
are temporarily stored here. These sperms do not reach to
seminal vesicle when vas deferens is cut and tied in
vasectomy.
(d) Statement in option (d) is false. It can be corrected as
Genital warts is a sexually transmitted disease caused by
Human Papilloma Virus. (HPV).
(d) Statements in option (a) and (c) are correct. Statement
in option (b) is incorrect. It can be corrected as
Lactation prevents conception because ovulation and
menstrual cycle does not occur during the period of
intense lactation up to 6 months following parturition.
(c) Statement in option (c) represents the incorrect
statement about ZIFT. It can be corrected as
In ZIFT, zygote or embryo up to 8-cells is transferred to
the Fallopian tubes. Embryos with more than 8
blastomeres are used in IUT (Intra Uterine Transfer).
(c) Statement in option (c) represents the false statement.
It can be corrected as
In GIFT (Gamete Intra Fallopian Transfer), gamete
(ovum) from donor is transferred into the Fallopian tube
of female who can provide suitable environment for
fertilisation and foetal growth, but cannot produce ova.
(d) Statement II is correct about WHOs. According to the
World Health Organisation (WHO), reproductive health
means a total well-being in all aspects of reproduction,
i.e. physical, emotional, behavioural and social.
Therefore, a society with people having physically and
functionally normal reproductive organs and normal
emotional and behavioural interactions among them in
all sex related aspects might be called reproductively
healthy.
l
l
Condoms prevent the ejaculated semen from entering
the female vagina.
Contraceptive pills have not effect on
spermatogenesis.
110 (b) Statements I and II are false and can be corrected
as
l
l
There are little or no side effects of tubectomy and
vasectomy.
The purpose of tubectomy is to block the passage of
ova.
Rest of the statements are correct.
112 (a) Statements III and IV show the correct statement.
Statements I and II are incorrect. These can be
corrected as
l
l
Chances of conception are nil until the mother
breastfeeds child up to six months following
parturition.
Children produced by IVF are not born with
abnormalities. An abnormality will only occur if the
donor gamete has some genetical abnormality in it.
113 (b) Statements III and IV are incorrect. They can be
corrected as
l
l
Sexually transmitted diseases are completely curable
except hepatitis-B, genital herpes and HIV infections.
MTPs are relatively safer up to 12 weeks of
pregnancy. Rest other statements are correct.
114 (d) Statements II and III are correct and can be
corrected as
l
l
Contraceptive oral pills are most popular among urban
women.
Removal of gonads is not a contraceptive procedure.
Rest other statements are true.
Answers & Explanations
l
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115 (d) Statements I, III, IV and V are correct. Statement II
is incorrect and can be corrected as
To avoid transmission of sexually transmitted diseases,
one should always practice safe sex, i.e. have protected
sex by using condoms during coitus.
130 (a) India was amongst the first country in the world to
initiate action plans and programmes at a national level
to attain total reproductive health as a social goal. These
programmes called ‘family planning’ were initiated in
1950s and were periodically assessed over the past
decades to determine their effects.
131 (c) IMR (Infant Mortality Rate) and MMR (Maternal
Mortality Rate) both are responsible for affecting the
growth rate inversely.
Here, if IMR has been increased then it will result in
decline in growth rate. While, decreased MMR will
cause rapid increase in growth rate.
Therefore, in the above situation, if IMR has been
increased and MMR has been decreased in a population,
it will not cause any significant change in growth rate.
132 (a) Breastfeeding is one of the natural contraceptive
methods. It is known to suppress the production of
Gonadotropin-Releasing Hormone (GnRH) and Follicle
Stimulating Hormone (FSH).
The release of these hormones triggers ovulation.
Breastfeeding also leads to increased level of
prolactin, a hormone that inhibits ovulation. So,
intensely lactating mothers do not generally conceive
due to the suppression of gonadotropins.
133 (d) Condoms are barriers made of thin rubber/latex
Answers & Explanations
sheath used to cover the penis in the males or vagina
and cervix in females. It prevents the deposition of
ejaculated semen into the vagina of the female. They do
not interfere with coital activity and protects the user
from contracting STDs.
134 (c) Option (c) represents the correct statements.
Diaphragms are physical barriers made of rubber that
are inserted into the female reproductive tract to cover
the cervix during coitus. They prevent the entry of
sperms through cervix.
135 (b) Option (b) represents the right statement. Other
statements are incorrect and can be corrected as
l
l
l
IUDs are inserted by doctors or expert nurses in the
uterus through vagina.
They do not suppress gametogenesis.
IUDs can be replaced whenever needed by the females.
136 (a) Administration of higher doses of progestogens or
progestogen-oestrogen combinations within 72 hrs of
137
138
139
140
141
coitus have been found to be very effective as
emergency contraceptives as they could be used to
avoid possible pregnancy due to rape or casual
unprotected intercourse. These drugs delay/disrupt the
ovulation and fertilisation process.
(c) The correct surgical procedure as a contraceptive
method is vasectomy performed in males, while in
females, is called tubectomy.
(b) AIDS (Acquired Immuno Deficiency Syndrome) is
a set of symptoms caused by HIV virus in humans. It is
transmitted through sexual contact from infected to a
healthy person. The HIV virus does not directly affect
sex organs as such but produces other set of symptoms
in the body of infected person.
(b) The correct statement regarding ZIFT is option (b).
The zygote or early embryo with up to 8 blastomeres is
collected from a female donor and transferred into the
Fallopian tube, this process is called Zygote Intra
Fallopian Transfer or ZIFT. Embryo more than 8
blastomeres is transferred into the uterus by the process
called Intra Uterine Transfer or IUT.
When ovum is collected from donor and transferred to
Fallopian tube of other female who cannot produce
ovum, this is known as Gamete Intra Fallopian Transfer
(GIFT).
(c) ICSI (Intra Cytoplasmic Sperm Injection) is a
specialised procedure to form an embryo in the
laboratory in which a sperm is directly injected into the
ovum placed in a nutrient broth.
(a) Statements I and III represent the correct reason for
why couples choose sterilisation techniques as a last
option for contraception.
Statements II and IV are incorrect and can be corrected
as
l
l
Sterilisation techniques have no effect on the sexual
urge/drive.
At present sufficient facilities are available in most
parts of our country for couples who want to undergo
sterilisation procedures.
142 (c) Statements I and IV are correct, while statements II
and III are incorrect regarding MTPs.
MTPs are done to get rid of unwanted pregnancies
either due to casual unprotected intercourse or failure of
the contraceptive used during coitus or rapes. MTPs are
also essential in certain cases where continuation of the
pregnancy could be harmful or even fatal either to the
mother or to the foetus or both. So, it requires the
assistance of qualified medical personnel.
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CHAPTER > 05
Principles of
Inheritance and
Variation
NEET
Å
KEY NOTES
Genetics is the branch of biology which deals with the
inheritance and variation of characters from parents to their
offspring.
Mendel’s Laws of Inheritance
Å
Gregor Mendel conducted hybridisation experiments on
garden peas for seven years (1856-1863). He applied
statistical analysis and mathematical logic while studying
inheritance patterns.
Å
Mendel investigated two opposing traits of 14 characters in
true breeding pea plant (produced by continuous
self-pollination and which showed stable trait inheritance).
The characters selected by Mendel are tabulated below
Contrasting Traits Studied by Mendel in Pea
Traits
Inheritance of One Gene
Å
Mendel observed one trait or character at a time, e.g. he
crossed a tall and a dwarf pea plants to study the inheritance
of one gene.
Å
He hybridised plants with alternate forms of a single trait
(monohybrid cross). The seeds produced by these crosses
were grown to develop into plants of Filial1 progeny or
F1-generation (F1 -plants).
Å
Mendel then self-pollinated the tall F1-plants to produce
plants of Filial 2 progeny or F2 -generation ( F2 -plants).
Å
In later experiments, Mendel also crossed pea plants with
two contrasting characters known as dihybrid cross.
Mendel’s Observation
Å
S. No. Characters
Dominant
Recessive
1.
Stem height
Tall
Dwarf
2.
Flower colour
Violet
White
3.
Flower position
Axial
Terminal
4.
Pod shape
Inflated
Constricted
5.
Pod colour
Green
Yellow
6.
Seed shape
Round
Wrinkled
7.
Seed colour
Yellow
Green
Å
Å
Å
Å
In F1 -generation, Mendel found that all pea plants were tall
and none was dwarf.
He also observed other pair of traits and found that F1-plant
always resembled either one of its parent and the trait of
other parent was not found.
In F2 -generation, he found that some of the offspring were
‘dwarf ’, i.e. the characters which were not seen in
F1-generation were expressed in F2 - generation.
The proportion of plants that were dwarf, were 1/4th of the
F2 -plants, while 3/4th of the F2 -plants were tall.
These contrasting traits (tall/dwarf) did not show any mixing
either in F1 or in F2 - generation as none was of intermediate
height.
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Similar results were obtained with the other traits that he
studied. Only one of the parental traits was expressed in
F1-generation, while in F2 - generation stage, both the traits
were expressed in the ratio of 3 : 1.
Å
Mendel also found identical results in dihybrid cross as in
monohybrid cross.
Mendel’s Inferences
Following inferences were made by Mendel based on his
observations
Å Mendel proposed that factors or genes pass down from
parent to offspring through gametes over successive
generations.
Å Genes are units of inheritance and they code for a pair of
contrasting traits called alleles (different forms of the same
gene).
Å The alleles of a character are denoted as capital and small
letters, e.g. T(tall) and t(dwarf).
Å Genotype is the genetic constitution of an individual while
the phenotype is the external appearance.
Å Dominant allele The factor or an allele pair, which can
express itself in both homozygous and heterozygous states.
Å Recessive allele The factor or allele pair, which can express
only in homozygous state.
Å Homozygous condition The state in which an organism has
two similar genes or alleles of a particular character, e.g. TT
or tt for tallness or dwarfness.
Å Heterozygous condition In this, an organism contains two
different alleles for a particular character, e.g. Tt.
Å In a monohybrid cross, genes controlling one character (e.g.
height) are considered, e.g. cross between TT × tt (Tall ×
Dwarf plant).
The resultant F1 progeny in such a cross is heterozygous
(Tt).
In F2 -generation, the recessive parental trait is expressed
without any blending which represents that alleles of
parental pair segregate during gamete formation. It is a
random process.
Å
Punnett square is the diagrammatic representation of
gametes produced by the parents, the formation of the
zygotes and F1 , F2 plants. It helps to calculate the
probability of all possible genotypes of offspring in a
genetic cross. It was developed by British geneticist,
Reginald C Punnett.
Å
Test cross is performed between the dominant
phenotype (obtained in F1 or F2 ) and recessive parent, so
as to determine the genotype of former. The resultant
progeny appear in ratio 1 : 1.
ww
(White flowers)
Interpretation Result
Å
tt
(Dwarf)
Parental
TT
Tt
Tt
Selfing
tt
F2-generation
Phenotypic ratio – 3 : 1
Genotypic ratio – 1 : 2 : 1
NEET
Unknown flower is
heterozygous dominant
Based on his observations on monohybrid crosses,
Mendel proposed two general rules in order to
consolidate his understanding of inheritance in
monohybrid crosses. Today, these rules are called the
principles or laws of inheritance. These are
Law of Dominance (First Law)
Å
Å
F1-generation
t
Unknown flower is
homozygous dominant
Å
Å
T
(Violet flowers)
Ww Ww W Dominant phenotype w ww ww
All flowers violet (Genotype unknown) 50% flowers violet
50% flowers white
Reciprocal cross A cross in which same two parents are
used in such a way that if in one experiment ‘A’ is used
as female parent and ‘B’ is used as male parent, in other
experiment ‘A’ will be used as male parent and ‘B’ is
used as female parent is called reciprocal.
t
Tt
(Tall)
w w
W Ww Ww
Å
Å
T
WW or Ww
w
Back cross The cross of an organism with the organism
of its previous generation is known as back cross.
n
×
w
Å
n
TT
(Tall)
w w
w w
Ww Ww W
ww
Homozygous
(White flowers) recessive
Characters are controlled by discrete units called factors.
Factors occur in pairs.
In a dissimilar pair of factors, one member of the pair is
dominant while the other is recessive.
This law is used to explain the expression of only one of
the parental characters in a monohybrid cross in the
F1-generation and the expression of both in the
F2 -generation. It also explains the proportion of 3:1 ratio
obtained in the F2 -generation.
Law of Segregation (Second Law)
Å
This law states that, though the parents contain two
alleles during gamete formation, the factors or alleles of
a pair segregate from each other, such that a gamete
receives only one of the two factors.
KEY NOTES
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CHAPTER 05 > Principles of Inheritance and Variation
Å
Hence, alleles do not show any blending and both the
characters are recovered as such in the F2 -generation, though
one of these is not seen in the F1-generation.
Å
All the patterns of inheritance could not be explained
exclusively on the basis of Mendel’s original principles alone
and certain complexities were observed by later workers
which deviated from Mendel’s laws or Mendelism.
1. Incomplete Dominance
Å
The F1 -progeny develop a new phenotype which do not
resemble either of the two parents and lies in between the
two. For example, inheritance of flower colour in
snapdragon (Antirrhinum) .
Å
In this case, both phenotypic and genotypic ratio is 1 : 2 : 1. The
phenotypic ratio deviates from the Mendelian ratio of 3 : 1.
Å
Å
Based upon this, Mendel proposed a second set of
generalisations or postulates which is called law of
independent assortment.
Law of Independent Assortment
(Third Law)
This law states that ‘when two pairs of traits are combined
in a hybrid, segregation of one pair of characters is
independent of the other pair of characters’ at the time of
gamete formation. It also gets randomly rearranged in the
offspring producing both parental and new combinations
of characters. This can be understood from the figure
given below
Parents
(Round yellow)
RRYY
Incomplete dominance result due to the production of
non-functional enzyme or no enzyme by the recessive allele.
RY
(Wrinkled green)
rryy
ry
Gametes
2. Codominance
Å
Å
Å
The F1 -progeny resemble both the parents due to the equal
expression of both alleles.
For example, ABO blood group in humans is controlled by
gene I which exhibit three alleles–IA , I B and i. IA and I B are
codominant alleles and these both are dominant over i.
Due to the presence of three different alleles, six genotype of
human ABO blood groups are possible. These are tabulated
below
Table Showing the Genetic Basis of Blood
Group in Human Population
Allele from
Parent 1
Allele from
Parent 2
Genotype of
Offspring
Blood Group of
Offspring
IA
IA
IA IA
A
IA
AB
IB
IA IB
A
I
i
A
I i
A
IB
IA
IA IB
AB
IB
IB
IB IB
B
B
I
i
IB i
B
i
i
ii
O
3. Multiple Allelism
Å
More than two alleles governs the same character. These are
found during population studies. The human blood group
gene provides an example of multiple allele as well as an
interesting dominance relationship.
Inheritance of Two Genes
Å
Å
To verify his results of monohybrid cross, Mendel also
crossed pea plants differing in two characters (dihybrid
cross). This helped him to understand inheritance of two
genes (i.e. two pairs of alleles) at a time.
It was found that inheritance of one pair of allele (one trait)
does not interfere in the inheritance of other pair of allele
(second trait).
(Round yellow)
RrYy
On
selfing
RY
F1-generation
RY
Gametes
Gametes
rY
Ry
ry
RRYy
RrYy
RrYy
RRyy
Rryy
ry
RRYy
rrYY
rrYy
Ry
RrYY
RrYY
RrYy
rY
RRYY
RrYy
rrYy
F2-generation
Rryy
rryy
Phenotypic Ratio Round yellow : Round green :
Wrinkled yellow : Wrinkled green = 9 : 3 : 3 : 1
Result of dihybrid cross where the two parents differed in two
pairs of contrasting traits, i.e. seed colour and seed shape
In 1900, de Vries, Correns and von Tschermak
rediscovered Mendel’s results independently. Due to
microscopy, they carefully observed cell division. This led
to discovery of chromosomes (structure in the nucleus that
appeared in pairs and divide just before each cell
division).
Chromosomal Theory of
Inheritance
It was proposed independently by Walter Sutton and
Theodore Boveri in 1902. They united the knowledge of
chromosomal segregation with Mendelian principles and
NEET
KEY NOTES
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called it chromosomal theory of inheritance. According to this
theory
Å
All hereditary characters must be with sperms and egg cells
as they provide bridge from one generation to the other.
Å
The hereditary factors must be carried by the nuclear material.
Å
Chromosomes are also found in pairs like the Mendelian
alleles.
Å
The two alleles of a gene pair are located on homologous
sites on the homologous chromosomes.
Å
The sperms and eggs have haploid sets of chromosomes,
which fuse to re-establish the diploid state.
The genes are carried on to the chromosomes.
Homologous chromosomes synapse during meiosis and get
separated to pass into different cells. This is the basis for
segregation and independent assortment.
Comparison between the Behaviour of
Chromosomes and Genes
Å
Å
Chromosomes
Genes
These occur in pairs.
These also occur in pairs.
Å
Thus, linkage is a phenomenon of genetic inheritance in
which genes of a particular chromosome show their
tendency to inherit together.
Å
Morgan and his group also found that even when genes
were grouped on the same chromosome, some genes
were tightly linked, i.e. linkage is stronger between two
genes, if the frequency of recombination is low.
Å
Whereas, the frequency of recombinations is higher, if
genes are loosely linked, i.e. linkage is weak between
two genes.
Å
Recombination of linked genes is by crossing over
(exchange of corresponding parts between the
chromatids of homologous chromosomes).
Polygenic Inheritance
Å
It was given by Galton in 1833. In this, traits are
controlled by three or more genes (multiple genes).
These traits are called polygenic traits.
Å
The phenotype shows participation of each allele and is
also influenced by the environment and is called
quantitative inheritance as the character/phenotype
can be quantified. For example, human skin colour
which is caused by a pigment melanin. The quantity of
melanin is due to three pairs of polygenes (A, B and C).
Å
If a black or very dark (AA BB CC) and white or very
light (aa bb cc) individuals marry each other, the
offspring show intermediate colour, also called mulatto
(Aa Ba Ca). A total of eight allele combinations are
possible in the gametes, forming 27 distinct genotypes.
Segregate at the time of gamete
Segregate at gamete formation and
formation such that only one of
only one of each pair is transmitted to a
each pair is transmitted to a gamete. gamete.
One pair segregates independently
of other pairs.
Å
Å
Å
One pair segregates independently of
another pairs situated on different
chromosome. However, segregation of
linked genes shows dependency on
each other.
It was done by Thomas Hunt Morgan and his colleagues.
Morgan carried out various dihybrid crosses in Drosophila
with the genes that were sex-linked, i.e. the genes present on
the X-chromosome.
Morgan selected fruitfly, Drosophila melanogaster for his
experiments because
They could be grown on simple artificial medium in the
laboratory.
Their life cycle is only about two weeks.
A single mating could produce a large number of flies.
It has four pairs of chromosomes which differ in size.
There was a clear differentiation of the sexes, i.e. male
(smaller) and female (bigger).
Pleiotropy
Å
It is the phenomenon in which a single gene product
may produce multiple or more than one phenotypic
effect.
Å
For example, phenylketonuria, a disorder caused by
mutation in the gene coding the enzyme phenylalanine
hydroxylase. The affected individuals show hair and
skin pigmentation and mental retardation.
Å
Therefore, it can be said that dominance is not an
autonomous feature of the gene, or its product, but it
depends on the production of a particular phenotype
from the gene product.
n
n
n
n
n
n
It has many types of hereditary variation, which can be
easily seen through low power microscope.
Linkage and Recombination
Å
Å
Morgan and his group observed in Drosophila that when the
two genes in a dihybrid cross were situated on the same
chromosome, the proportion of parental gene combinations
were much higher than the non-parental type.
They attributed this due to physical association of the two
genes and coined the term ‘linkage’ to describe this physical
association of genes on a chromosome and the term
‘recombination’ to describe the generation of non-parental
gene combinations.
NEET
Sex-Determination
Å
The establishment of sex through differential
development in an individual at the time of zygote
formation is called sex-determination.
Å
Henking in 1891, could trace a specific nuclear structure
all through spermatogenesis in few insects. He observed
that 50% of sperms received this specific structure after
spermatogenesis, whereas the other 50% of sperms did
not receive it. He named this structure as X-body.
KEY NOTES
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CHAPTER 05 > Principles of Inheritance and Variation
Scientists further explained that X-body was a chromosome
and called it as X-chromosome.
Å
Å
The chromosomal theory of sex-determination was worked
out by EB Wilson and Stevens (1902-1905). They named
XY-chromosomes as allosome or sex chromosomes and
other chromosomes, which have no relation with the sex and
contain genes, which determine the somatic characters as
autosomes (AA).
Å
The mutations are of following types
Mutation
Gene mutations
Point
mutation
Thus, on the basis of the type of allosome present in the
gamete, the parents can be of two types
Homogametic, i.e. producing similar gametes.
Frameshift
mutation
Chromosomal mutations
Structural variation
aberrations
Aneuploidy
Numerical
variations
Polyploidy
n
n
Å
Heterogametic, i.e. producing different gametes.
Sex-determination pattern in different organisms is as
follows
Types of sexdetermination
mechanism
Features
Examples
XX-XY method
Females are homogametic as all
the chromosomes bear only
X-chromosome.
Males are heterogametic as half
of the gametes have
X-chromosomes and the other
half bears Y-chromosomes.
Humans,
Drosophila, etc.
Females are homogametic as all
gametes bear only
X-chromosome.
Males are heterogametic as half
of the gametes bear
X-chromosome and the other
half does not have any
sex-chromosome.
Roundworms,
insects, etc.
ZW-ZZ method
Females are heterogametic
half of the gametes have
Z-chromosome and the other
half have W-chromosome.
Males are homogametic as all
the gametes possess only
Z-chromosome.
Fishes, reptiles etc.
ZO-ZZ method
Females are heterogametic as
half of the gametes have
Z-chromosome and the other
half has no chromosome.
Males are homogametic and all
the gametes bear only
Z-chromosome.
Moths, butterflies,
etc.
Unfertilised egg produces a
haploid male.
Fertilised egg produces a
diploid gamete.
Honeybees, etc.
XX-XO method
Monosomy
Å
Å
Å
Å
Trisomy
Autopolyploidy
Allopolyploidy
Mutation occurring due to change in a single base pair
of DNA. This is called point mutation, e.g. sickle-cell
anaemia.
Deletions and insertions of base pairs of DNA cause
frameshift mutation.
The loss or gain of a segment of DNA, results in
structural alteration in chromosomes because genes are
located on the chromosomes. This alteration in
chromosomes results in abnormalities and is common in
cancerous cells.
When members of a homologous pair of chromosomes
fail to segregate during meiosis, aneuploidy occurs. It
means, there is loss or gain of one or more chromosomes.
Monosomy, i.e. lack of one chromosome of normal
complement.
Trisomy, i.e. three instead of normal two
chromosomes.
n
n
Å
Polyploidy occurs when there is failure of cytokinesis
after telophase stage of cell division resulting in an
increase in a whole set of chromosomes in an organism.
In this phenomenon, the cell has loss or gain of three,
four or more sets of chromosomes.
Autopolyploids are polyploids with multiple
chromosome sets derived from a single species.
Allopolyploids where chromosomes are derived
from different species, i.e. result of multiplying the
chromosome number and forming a hybrid.
n
Haplodiploidy
n
Mutation
Å
Å
It is a sudden, stable and inheritable change in genetic
material or DNA sequences of an organism. The organism,
which undergoes mutation is called mutant.
The chemical and physical factors that induce mutations are
called mutagens, e.g. UV radiations, etc.
Pedigree Analysis
Å
Å
The analysis of traits in several generations of a human
family in the form of a family tree or diagram is called
pedigree analysis. It serves as a strong tool, which is
utilised to trace the inheritance of a specific trait,
abnormality or disease.
Inheritance pattern of traits in human beings cannot be
studied by crosses as in case of other organisms due to
following reasons
The progeny produced is very small (usually one)
and therefore, takes long time.
Controlled crosses cannot be performed.
n
n
NEET
KEY NOTES
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The symbols used in pedigree analysis are given below
Å
Various Mendelian disorders are tabulated below
Male
Disorders
Characteristics
Female
Colour blindness
˜
Sex unspecified
˜
Affected individual
Mating
˜
Haemophilia
˜
Heterozygous or Carrier male
˜
Heterozygous or Carrier female
Mating between relatives
(consanguineous mating)
Sickle-cell
anaemia
Parents above and
children below
(in order of birth-left to right)
˜
˜
˜
Phenylketonuria
Parents with male child
affected with disease
˜
˜
Thalassemia
Dizygous twins
˜
˜
˜
Monozygous twins
˜
5
Five unaffected offspring
Sex-linked recessive disorder caused due to
mutation in genes present on X-chromosome.
Mostly females are carrier while males contract
the disease.
Affected person fails to discriminate red and
green colour.
Sex-linked recessive disorder which prevent
clotting of blood.
Heterozygote females are carrier who transmit
the disease to sons.
Autosome linked recessive trait.
Caused due to the substitution of glutamic acid
by valine as the sixth codon of β-globin gene
gets substituted from GAG to GUG.
RBCs become sickle-shaped under low O2
tension.
Autosomal recessive trait.
Individual lack enzyme that convert
phenylalanine into tyrosine leading to
accumulation of phenylpyruvic acid in body,
brain, etc.
Autosome linked recessive trait.
α-thalassemia is caused due to the mutation in
HBA1 and HBA2 genes on chromosome 16.
β-thalassemia is caused due to the mutation in
HBB gene on chromosome 11.
The rate of synthesis of α or β-chain gets
reduced leading to the formation of abnormal
haemoglobin.
Symbols used in the human pedigree analysis
Genetic Disorders
Å
Å
Chromosomal Disorders
Å
These are disorders or illness which caused by one or more
abnormalities in the autosomes or sex chromosomes of the
person. Thus, referred to as autosomal disorders or
sex-linked disorders, respectively.
n
The genetic disorders are divided into
n
Genetic Disorders
Å
Mendelian Disorders
e.g. Haemophilia, cystic
fibrosis, colour blindness,
Sickle-cell anaemia, thalassemia,
phenylketonuria, etc.
Chromosomal Disorders
e.g. Down’s
syndrome, Turner’s syndrome,
Klinefelter’s syndrome, etc.
Mendelian Disorders
Å
It caused due to excess, the absence or abnormal
arrangement of one or more chromosomes. These are of
two types as follows
Autosomal abnormality or disorder, e.g. Down’s
syndrome (Mongolian idiocy).
Sex chromosome abnormality, e.g. Klinefelter’s
syndrome and Turner’s syndrome.
Various chromosomal disorders are tabulated below
Disorders
Down’s syndrome
Sex-linked recessive disorder, e.g. colour blindness and
haemophilia.
˜
˜
Klinefelter’s syndrome
It caused due to alteration or mutation in a single gene.
These are of two types
n
Characteristics
˜
˜
Turner’s syndrome
˜
˜
n
Autosomal recessive disorder, e.g. thalassemia,
phenylketonuria and sickle-cell anaemia.
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21 trisomy (described by Langdon Down)
Cause short statured, furrowed tongue,
small round head, palm crease, retarded
mental development and physical
appearance.
Presence of an additional
X-chromosome (XXY).
Cause sterility, gynaecomastia, overall
masuline development, etc.
Absence of one X-chromosome (XO).
Sterile females, rudimentary ovaries,
lack of secondary sexual characters.
KEY NOTES
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97
CHAPTER 05 > Principles of Inheritance and Variation
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1
~ Mendel's Laws of Inheritance
1 Genetics is the branch of biology which deals with
(a) variation
(c) Both (a) and (b)
8 How many pairs of true breeding varieties were
selected by Mendel for his experiment on pea plant?
(b) inheritance
(d) study of characters
2 The inheritance of characters from parents to
(a) 12
(a)
(b)
(c)
(d)
is called
considered by Mendel in his experiments on pea?
(a)
(b)
(c)
(d)
(b) Lathyrus odoratus
(d) Mirabilis jalapa
5 Which one from those given below is the period of
Mendel’s hybridisation experiments?
(a) 1856-1863
(c) 1857-1869
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(a)
(b)
(c)
(d)
manifested in two traits which were
7 A true breeding line is characterised by the presence of
(a) stable trait inheritance due to the continuous selfpollination
(b) varying traits in different generations due to the cross
pollination
(c) single trait in all generations due to allogamy
(d) varying trait inheritance in a single generation due to
geitonogamy
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his experiment on pea plant?
(b) 1840-1850
(d) 1870-1877
(b) non-zygote
(d) opposite
Stem – Tall or Dwarf
Trichomes – Glandular or Non-glandular
Seed – Green or Yellow
Pod – Inflated or Constricted
11 Which is correct about traits choosen by Mendel for
6 Mendel investigated characters in garden pea plant
(a) similar
(c) identical
7 and 7
8 and 6
6 and 8
5 and 9
10 Among the following characters, which one was not
(b) heredity
(d) resemblance
4 Mendel’s hybridisation experimental material was
(a) Pisum sativum
(c) Oryza sativa
(d) 15
how many traits were dominant and recessive?
(b) heredity
(d) resemblance
3 The tendency of offspring to differ from their parents
(a) variation
(c) inheritance
(c) 14
9 Out of 7 contrasting trait pairs selected by Mendel,
offspring is
(a) variation
(c) inheritance
(b) 13
Terminal pod was dominant
Constricted pod was dominant
Green coloured pod was dominant
Tall plants were recessive
12 What contributed to Mendel’s success?
I. Selection of pureline pea varieties.
II. Knowledge of history.
III. Selecting one character at a time.
IV. Statistical analysis and mathematical logic.
Choose the correct option.
(a) I, II, III and IV
(c) I, III and IV
(b) II and III
(d) II, III and IV
TOPIC 2 ~ Inheritance of One Gene
13 The first hybrid progeny obtained by Mendel were
called
(a) F1 -progeny
(c) F 2 -progeny
(b) F 0 -progeny
(d) F 3 -progeny
14 F1 -progeny of a cross between pure tall and dwarf
plant is always
(a)
(b)
(c)
(d)
tall
short
intermediate
None of these
15 According to Mendel’s observation, which generation
of progeny always represents the phenotype of the
dominant parent?
(a) F4
(b) F2
(c) F1
(d) F0
16 The Mendel crossed true breeding tall and dwarf plant
varieties in his experiment. Tallness was the dominant
character and dwarfness was recessive. The recessive
character appeared in
(a) F1
(c) F3
(b) F 2
(d) F2 and F 3
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17 How did Mendel obtained recessive (dwarf) character
in F2 -generation?
(a) By self-pollinating F1 (b) By self-pollinating F2
(c) By cross-pollinating F1 (d) By cross-pollinating F2
18 The proportion of plants that were dwarf and tall,
respectively in F2 -generation of Mendel’s experiment
was
1
th and
4
2
(c) rd and
3
(a)
3
th
4
1
rd
3
3
th and
4
1
(d) rd and
3
(b)
1
th
4
4
rd
3
19 Mendel crossed tall and dwarf plants. In
F2 -generation both the tall and dwarf plants were
produced. This shows
(a)
(b)
(c)
(d)
blending of characters
atavism
non-blending of characters
intermediate characters
20 During his experiments, Mendel used the term factor
for
(a) genes
(c) characters
(b) traits
(d) qualities
21 Genes which codes for a pair of contrasting characters
are
(a) recessive character
(c) alleles
(b) dominant character
(d) alternative gene
22 Choose the incorrect match.
(a) Phenotype – Physical appearance of an organism
(b) Genotype – Expressed genes
(c) Homozygous – Identical alleles of a gene present at the
same locus
(d) Heterozygous – Genes of an allelic pair are not same
23 Number of gametes produced by a homozygous and a
heterozygous individuals of genotype AA and Aa,
respectively are
(a) 1 and 2
(c) 3 and 5
(b) 2 and 3
(d) many
24 A cross in which parents differ in a single pair of
contrasting character is called
(a) monohybrid cross
(c) trihybrid cross
(b) dihybrid cross
(d) tetrahybrid cross
25 The phenotypic ratio of a monohybrid cross in
F2 -generation is
(a) 3 : 1
(c) 2 : 1 : 1
(b) 1 : 2 : 1
(d) 9 : 3 : 3 : 1
26 The genotypic ratio of a monohybrid cross in
F2 -generation is
(a) 3 : 1
(c) 2 : 1 : 1
(b) 1 : 2 : 1
(d) 9 : 3 : 3 : 1
27 F2 -generation in a Mendelian cross showed that both
genotypic and phenotypic ratios are same as 1 : 2 : 1.
It represents a case of
CBSE-AIPMT 2012
(a) codominance
(b) dihybrid cross
(c) monohybrid cross with complete dominance
(d) monohybrid cross with incomplete dominance
28 If the male plant has the genotype TT and the female
plant has the genotype tt then they contribute pollen
and egg, respectively with
(a) T and T gametes
(c) TT and tt gametes
(b) tt and TT gametes
(d) T and t gametes
29 Graphical representation to calculate the probability
of all possible genotype of an offspring in genetic
cross is called
(a) Bunett square
(c) Punnett square
(b) Morgan square
(d) Mendel square
30 Test cross involves a cross between
(a)
(b)
(c)
(d)
recessive F1 -plant and dominant F2 -plant
recessive F2 -plant and dominant F3 -plant
dominant F2 -plant and recessive parent plants
dominant F2 -plant and heterozygous parent plants
31 Mendel performed test cross to know the
(a) genotype of F1
(c) genotype of F 3
(b) genotype of F 2
(d) genotype of F 4
32 When alleles of two contrasting characters are present
together and one of the character expresses itself
during the cross while the other remains hidden gives
the
(a)
(b)
(c)
(d)
law of purity of gametes
law of segregation
law of dominance
law of independent assortment
33 The allele which expresses itself in both homozygous
and heterozygous condition is called
(a)
(b)
(c)
(d)
dominant allele
recessive allele
incomplete dominant allele
split allele
34 3:1 ratio in F2 -generation is explained by
(a)
(b)
(c)
(d)
law of partial dominance
law of dominance
law of incomplete dominance
law of purity of gametes
35 The law of dominance is applicable in inheritance of
(a)
(b)
(c)
(d)
seed colour in pea
flower colour in Mirabilis jalapa
starch grain size in pea
roan coat colour in cattles
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CHAPTER 05 > Principles of Inheritance and Variation
36 Mendel’s principle of segregation means that the
germ cells always receive
(a)
(b)
(c)
(d)
one pair to alleles
one quarter of the genes
either one allele of father or one allele of mother
any pair of alleles
37 The law based on fact that the characters do not show
any blending and both the characters are recovered as
such in F2 -generation although one character was
absent in F1 -progeny, is
(a)
(b)
(c)
(d)
law of purity of gametes
law of independent assortment
law of incomplete dominance
law of dominance
38 Mendel crossed tall and dwarf plant. In F2 -generation
the observed ratio was 3:1 (tall : short). From this
result, he deduced
I. law of dominance.
II. law of independent assortment.
III. law of segregation.
IV. incomplete dominance.
Choose the correct option.
(a) I, II, III and IV
(c) II, III and IV
(b) I and III
(d) I, II and III
39 Correctly select the genotype and phenotype of
F1 -generation (R = dominant and red, r = recessive
and white) from the given cross in plant snapdragon
showing incomplete dominance.
42 TtRr represents (heterozygous tall, heterozygous
pink). If this plant is self crossed then
(T–dominant, t–recessive, R–dominant, r–recessive)
I. 25% plants have red flowers.
II. 25% plants have white flowers.
III. 50% plants have pink flowers.
IV. 50% plants are tall.
Choose the correct option.
(a) I and II
(c) II, III and IV
(b) I, II and III
(d) I, II, III and IV
43 Which Mendelian idea is depicted by a cross in which
the F1 -generation resembles both the parents?
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(a) Incomplete dominance (b) Law of dominance
(c) Inheritance of one gene (d) Codominance
44 What will be the ratio of offspring in a cross between
the red coloured and pink coloured flowers of
Mirabilis jalapa.
(a) Red : Pink = 1 : 1
(c) Red : Pink = 1 : 3
(b) Red : Pink = 3 : 1
(d) Red : Pink = 2 : 3
45 The recessive trait in case of incomplete dominance is
seen due to the
(a) non-functional enzyme produced by modified gene
(b) absence of any enzyme that may otherwise be produced
by modified gene
(c) normal or less efficient enzyme produced by recessive
allele
(d) Both (a) and (b)
46 The ABO blood groups are controlled by
RR
rr
P-generation
R
r
Gametes
F1-generation
(a) Rr and white
(c) Rr and pink
(b) Rr and red
(d) cannot predict
40 Theoretically in incomplete dominance one allele
functions as normal, while another allele may
function as
(a)
(b)
(c)
(d)
normal allele
non-functional allele
normal but less efficient allele
All of the above
41 Incomplete dominance is similar to codominance in
having identical
(a)
(b)
(c)
(d)
phenotypic ratio
genotypic ratio
Both (a) and (b)
None of the above
(a) I-gene
(c) B-gene
(b) c-gene
(d) n-gene
47 Out of the three alleles of gene I, the sugar polymers
on the plasma membrane of RBCs is controlled by
how many alleles?
(a) All three
(c) One
(b) Two
(d) O
48 In human blood group inheritance
(a)
(b)
(c)
(d)
IA and IB are codominant
IA and IB are dominant over i
IA is dominant over IB
Both (a) and (b)
49 If two persons with ‘AB’ blood group marry and have
sufficiently large number of children, these children
could be classified as ‘A’ blood group : ‘AB’ blood
group : ‘B’ blood group in 1 : 2 : 1 ratio. Modern
technique of protein electrophoresis reveals presence
of both ‘A’ and ‘B’ type proteins in ‘AB’ blood group
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individuals. This is an example of
(a) codominance
(c) partial dominance
(b) incomplete dominance
(d) complete dominance
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100
50 In a marriage between male with blood group A and
female with blood group B, the progeny had either
blood group AB or B. What could be the possible
genotype of parents?
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(a)
(b)
(c)
(d)
IA i (Male) : IBIB (Female)
IA IA (Male) : IBIB (Female)
IA IA (Male) : IBi (Female)
IA i (Male) : IBi (Female)
(b) I, II and III
(d) I, III and V
54 When there are more than two alleles controlling the
mother is ‘B’. Then predict the blood group of the
AIIMS 2019
progeny.
A, AB
A, B, AB, O
B, AB
O, A, B
same character. These are called
(a) pleiotropy
(c) multiple alleles
(b) polyalleles
(d) All of these
55 Which of the following option (s) is/are correct for
starch synthesis in pea seeds controlled by single gene
which has two allelic forms B and b?
52 The genotypes of a husband and wife are I A I B and
I A i. Among the blood types of their children, how
many different genotypes and phenotypes are
possible?
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(a)
(b)
(c)
(d)
Dominance
Codominance
Multiple allele
Incomplete dominance
Polygenic inheritance
(a) I, IV and V
(c) II, III and V
51 Blood group of the father is ‘A’ and blood group of
(a)
(b)
(c)
(d)
I.
II.
III.
IV.
V.
3 genotypes; 3 phenotypes
3 genotypes; 4 phenotypes
4 genotypes; 3 phenotypes
4 genotypes; 4 phenotypes
(a)
(b)
(c)
(d)
BB is round seed with large starch synthesis
bb is wrinkled seed with large starch synthesis
Bb is round seed with less starch synthesis
All of the above
56 Starch synthesis gene in pea plant in heterozygous
condition produces starch grain of intermediate size.
This shows
53 Which of the following characteristics represents
‘Inheritance of blood groups’ in humans? NEET 2018
(a)
(b)
(c)
(d)
complete dominance
incomplete dominance
codominance
None of the above
TOPIC 3 ~ Inheritance of Two Genes
57 The types of gametes formed by the genotype RrYy
are
(a) RY, Ry, rY, ry
(c) Ry, Ry, Yy, ry
(b) RY, Ry, ry, ry
(d) Rr, RR, Yy, YY
58 In law of independent assortment how many factors
are involved (for a dihybrid cross)
(a) 2
(b) 3
(c) 4
shape (RR) was dominant over wrinkled seeds (rr)
and yellow colour (YY) was dominant over green
colour (yy). What are the expected phenotypes in the
F1 -generation of the cross RRYY × rryy?
Only round seeds with yellow cotyledons
Only wrinkled seeds with yellow cotyledons
Only wrinkled seeds with green cotyledons
Round seeds with yellow cotyledons and wrinkled
seeds with yellow cotyledons
60 In cross between pure breeding pea plants having
yellow round (YYRR) and green wrinkled (yyrr)
seeds, find out the total seeds (plants) having yellow
colour in F2 -generation.
(a) 12
(c) 14
(b) 10
(d) 11
(YYRR) and green wrinkled (yyrr) seeds, what will
be the ratio between seeds having yellow and green
seed colour?
(a) 3 : 2
(b) 3 : 1
(c) 9 : 7
(d) 7 : 9
62 Total number of round seed in the F2 -generation of a
(d) 1
59 In Mendel’s experiments with garden pea, round seed
(a)
(b)
(c)
(d)
61 In a cross between plants having yellow round
cross between plants having pure yellow round and
pure green wrinkled seeds is
(a) 9
(b) 12
(c) 11
(d) 1
63 Ratio observed in dihybrid cross (phenotypically)
(a) 3 : 1
(c) 9 : 7
(b) 1 : 2 : 1
(d) 9 : 3 : 3 : 1
64 The number of different genotypes observed in the
F2 -generation of a dihybrid cross are
(a) 9
(b) 12
(c) 4
(d) 6
65 Mendel’s result on inheritance of characters were
rediscovered by
(a) de Vries
(c) von Tschermak
(b) Correns
(d) All of these
66 The literal meaning of chromosome is
(a) painted body
(c) doubling body
(b) coloured body
(d) thread-like body
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CHAPTER 05 > Principles of Inheritance and Variation
67 The concept of chromosome movement during
meiosis to explain Mendel’s laws was used by
(a)
(b)
(c)
(d)
Sutton and Boveri
Malthus
Correns
Morgan
68 The chromosomes as well as genes occur in pair and
the two alleles of a gene pair are located on
(a)
(b)
(c)
(d)
homologous chromosomes
non-homologous chromosomes
single chromosome
All of the above
69 Who proposed the chromosomal theory of inheritance?
(a)
(b)
(c)
(d)
Sutton and Mendel
Boveri and Morgan
Morgan and Mendel
Sutton and Boveri
70 Experimental evidences of chromosomal theory of
inheritance was given by
(a) S Boveri
(c) de Vries
Drosophila melanogaster
Mangifera indica
Mirabilis jalapa
Drosophila indica
whether dominant or recessive are transmitted from
generation to generation in
changed form
unaltered form
altered form
disintegrated form
present on
(a)
(b)
(c)
(d)
X-chromosome
different chromosome
heterologous chromosome
paired chromosome
76 Strength of the linkage between the two genes is
(a)
(b)
(c)
(d)
proportionate to the distance between them
inversely proportionate to the distance between them
depend on the chromosomes
depend upon the size of chromosomes
(a)
(b)
(c)
(d)
50% each
72% and 8.3%, respectively
0.3% and 53%, respectively
1.3% and 37.2%, respectively
78 In a test cross involving F1 dihybrid flies, more
parental-type offspring were produced than the
recombinant type offspring. This indicates
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73 The figure depicts.
Possibility I
75 Linked genes that were observed by Morgan were
were linked tightly, while white and miniature wing
were loosely linked. The per cent recombination
shown by these genes were
72 Both chromosome and gene (Mendelian factors)
(a)
(b)
(c)
(d)
(a) Sutton and Boveri – Chromosome theory
(b) Walter and Boveri – Behaviour of chromosome during
cell divisions
(c) TH Morgan
– Mutation
(d) Henking
– Barr bodies
77 In Morgan’s experiment, white and yellow genes
(b) TH Morgan
(d) W Sutton
71 Morgan’s experimental organism was
(a)
(b)
(c)
(d)
74 Choose the incorrect pairing among the following.
Possibility II
Two pair of
homologous
chromosomes
(a) chromosomes failed to separate during meiosis
(b) the two genes are linked and present on the same
chromosome
(c) Both of the characters are controlled by more than one
gene
(d) the genes are located on two different chromosomes
79 The frequency of recombination between gene pairs
Anaphase-I (Meiosis-I) Anaphase-I (Meiosis-I)
on the same chromosome as a measure of the distance
between genes was explained by
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(a) Gregor J Mendel
(c) Sutton-Boveri
Anaphase-II (Meiosis-II) Anaphase-II (Meiosis-II)
(b) Alfred Sturtevant
(d) TH Morgan
80 What map unit (centi Morgan) is adopted in the
construction of genetic maps?
Germ cells
(a)
(b)
(c)
(d)
Linkage
Independent assortment
Law of dominance
Equational division
Germ cells
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(a) A unit of distance between two expressed genes
representing 100% cross over
(b) A unit of distance between genes on chromosomes,
representing 1% cross over
(c) A unit of distance between genes on chromosomes,
representing 50% cross over
(d) A unit of distance between two expressed genes
representing 10% cross over
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102
81 Map units on linkage map cannot be relied upon to
calculate physical distances on a chromosome for
which of the following reasons?
(a) The relationship between recombination frequency and
map units is different in every individual
(b) Physical distances between genes change during the
coures of cell cycle
(c) Linkage map distances are identical between males and
females
(d) The frequency of crossing over varies along the length
of the chromosome
82 Linkage group is
(a)
(b)
(c)
(d)
linearly arranged group of linked gene
non-linearly arranged group of linked gene
non-linearly arranged group of unlinked gene
non-linearly arranged group of single gene
83 Linkage groups are always present on the
(a) homologous chromosomes
(b) analogous chromosomes
(c) sex chromosomes
(d) heterologous chromosomes
84 Genetic maps can be used in human genome project
(a)
(b)
(c)
(d)
starting point in the sequencing of whole genome
measure the distance between genes
map the position of genes on chromosomes
All of the above
85 Genes A, B and C are linked. Genes A and B are more
close than A and C.
I. A might be before B and C.
II. B might be between A and C.
III. C might be between A and B.
IV. More crosses cannot occur between A and C than
A and B.
Find out the correct option for the given information.
(a)
(b)
(c)
(d)
I and II
II and III
III and IV
I, II and IV
TOPIC 4 ~ Polygenic Inheritance and Pleiotropy
86 Polygenic traits are controlled by
(a)
(b)
(c)
(d)
one gene
two genes
three or more genes
mutant genes
87 The polygenic traits
(a)
(b)
(c)
(d)
are influenced by environment
phenotype reflect the contribution of each allele
effect of each allele is additive
All of the above
88 In human skin colour which is a polygenic trait, all
dominant and all recessive alleles show
(a)
(b)
(c)
(d)
Darkest and lightest skin colour, respectively
Lightest and darkest skin colour, respectively
Only darkest skin colour
Only lightest skin colour
89 In human skin colour inheritance, the genotype with
three dominant and three recessive alleles will
produce
(a) darkest skin colour
(b) lightest skin colour
(c) intermediate skin colour
(d) patches of black and white
90 A pleiotropic gene
(a) is not found in humans
(b) is a single gene which exhibit multiple phenotypic
expressions
(c) show effect on metabolic pathways, so as to produce
various phenotypes
(d) Both (b) and (c)
91 Phenylketonuria is caused due to
(a)
(b)
(c)
(d)
pleiotropy
multiple alleles
codominance
incomplete dominance
92 Phenylketonuria in human
(a)
(b)
(c)
(d)
manifests through phenotypic expressions
is characterised by mental retardation
leads to hair reduction and skin pigmentation
All of the above
93 Which one of the following pairs is wrongly
matched?
(a)
(b)
(c)
(d)
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XO type of sex-determination – Grasshopper
ABO blood grouping – Codominance
Starch synthesis in pea – Multiple allele
TH Morgan – Linkage
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CHAPTER 05 > Principles of Inheritance and Variation
TOPIC 5 ~ Sex-Determination
94 Sex-determination is controlled by … A… and the
remaining chromosomes which are not involved in
sex-determination are …B… .
(a)
(b)
(c)
(d)
A
Allosomes
Allosomes
Sex-chromosomes
Autosomes
B
Autosomes
Sex-chromosomes
Allosomes
Sex-chromosomes
(c) Male Drosophila – Heterogametic
(d) None of the above
99 The chromosomal denotation for heterogametic
female and homogametic males are
(a) ZW and ZZ
(c) XX–XO
100 A human male contains the karyotype of … A… and a
human female has …B… chromosomes.
95 Choose the incorrect pair with respect to sex
determination in different organisms.
(a)
(b)
(c)
(d)
Grasshopper
Birds
Drosophila
Human
= XO type
= ZZ-ZW type
= XX-XO type
= XX-XY type
96 In XX and XY type of sex-determination,
(a)
(b)
(c)
(d)
males are heterogametic
females are isogametic
Both (a) and (b)
None of the option is correct
97 Male heterogamety is seen in
(a) Humans
(c) Drosophila
(b) Grasshopper
(d) All of these
98 Choose the incorrect pair amongst the following.
(a) Male bird – Homogametic
(b) Female bird – Heterogametic
(b) ZO–ZZ
(d) Both (a) and (b)
(a)
(b)
(c)
(d)
A
44 + XX
44 + XY
44 + XO
44 + XX
B
44 + XY
44 + XX
44 + XX
44 + XO
101 The number of chromosomes in females and males
honeybees are
(a)
(b)
(c)
(d)
32
16
32 and 16, respectively
16 and 32, respectively
102 The unfertilised eggs in honeybees develop into
(a) males
(c) worker
(b) queen
(d) Both (a) and (c)
103 In honeybees, male and female gametes are produced
through
(a) mitosis
(c) meiosis
(b) mitosis and meiosis, respectively
(d) meiosis and mitosis, respectively
TOPIC 6 ~ Mutation
104 Mutation is a phenomena which results in alteration
in sequences of
(a) DNA
(c) proteins
(b) RNA
(d) Both (a) and (b)
(a) change in genotype
(b) change in phenotype
(c) change in metabolism (d) All of these
106 Chromosomal abberation is commonly found in the
(b) normal cells
(d) autosomal cells
107 Point mutation arises due to the change in
(a)
(b)
(c)
(d)
Transition = 8, Transversion = 4
Transition = 4, Transversion = 4
Transition = 8, Transversion = 4
Transition = 4, Transversion = 8
109 Sickle-cell anaemia is a classical example of
105 Mutation may result in
(a) cancer cells
(c) healthy cells
(a)
(b)
(c)
(d)
single base DNA
single base pair of DNA
segment of DNA
double base pair of DNA
108 If there are four different types of nitrogenous bases
(A, T, G and C) then how many different types of
transitions and transversion are possible?
(a)
(b)
(c)
(d)
frame-shift mutation
point mutation
Both (a) and (b)
None of the above
110 Frame-shift mutation arises due to
(a)
(b)
(c)
(d)
deletion of base pair of DNA
insertion of base pair of DNA
Both (a) and (b)
change in single base pair of DNA
111 Mutagens are
(a)
(b)
(c)
(d)
chemical agents which cause change in DNA
physical agents which cause mutation
Both (a) and (b)
None of the abvoe
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104
TOPIC 7 ~ Genetic Disorders
112 Analysis of traits of several generation of a family in
the form of diagram is called
(a) gene analysis
(c) allele analysis
(b) chromosome analysis
(d) pedigree analysis
113 Pedigree analysis is very important in human beings
because
(a)
(b)
(c)
(d)
it helps genetic counselors to avoid disorders
it shows origin of traits
it shows the flow of traits in family
All of the above
(a)
(b)
(c)
(d)
character is carried by Y-chromosome
character is sex-linked recessive
character is sex-linked dominant
character is recessive autosomal
118 In the following human pedigree, the filled symbols
represent the affected individuals. Identify the type of
given pedigree.
114 Identify the correct choice for given symbols
(A and B).
A
(a)
(b)
(c)
(d)
B
A–Consanguineous mating; B–Mating
A–Mating; B–Mating between relatives
A–Mating; B–Consanguineous mating
Both (b) and (c)
115 Identify the symbols given below and the correct
option with respect of A, B , C and D.
A
B
C
D
(a) A–Male, B–Female, C–Sex unspecified, D–Affected
male
(b) A–Male, B–Female, C–Sterile, D–Carrier male
(c) A–Male, B–Female, C–Fertile, D–Affected female
(d) A–Female, B–Male, C–Sex unspecified, D–Carrier
female
(a) X-linked dominant
(c) Autosomal dominant
(b) Autosomal recessive
(d) X-linked recessive
119 In a family, father had a trait but mother did not. All
their sons and daughter had this trait. The same trait
was found in some grand daughters, though daughter
were married to the normal persons.
Choose the correct pedigree chart for this condition.
(a)
116 Identify the type of inheritance in the given diagram.
(b)
(c)
(a)
(b)
(c)
(d)
Dominant X-linked
Recessive X-linked
Dominant Y-linked
Cytoplasmic or Mitochondrial inheritance
117 Following pedigree chart shows
(d)
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CHAPTER 05 > Principles of Inheritance and Variation
120 Observe the pedigree chart given below. Find out the
126 A man whose father was colourblind marries a
woman, who had a colourblind mother and normal
father. What percentage of male children of this
CBSE-AIPMT 2014
couple will be colourblind ?
cause of trait, i.e. it is due to
(a) 25%
(c) 50%
(b) 0%
(d) 75%
127 A normal woman whose father was colourblind,
(a)
(b)
(c)
(d)
marries a normal man. What kinds of children can be
AIIMS 2018
expected and in what proportion ?
Incompletely dominant allele
Dominant allele
Either dominant or recessive allele
Recessive allele
121 The diagram given below show the inheritance of
haemophilia in a family. What will be the genotype of
the individual marked M?
(a) All daughters normal, 50% of sons colourblind
(b) All daughters normal, all sons colourblind
(c) 50% daughters colourblind, all sons normal
(d) All daughters colourblind, all sons normal
128 Which of the following most appropriately describes
haemophilia?
(a)
(b)
(c)
(d)
M
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X-linked recessive gene disorder
Chromosomal disorder
Dominant gene disorder
Recessive gene disorder
129 In haemophilia, the affected protein is a part of a
cascade of protein which is involved in the
(a) M − XY
(c) M − X h X h
(b) M − XX
(d) M − X h X
122 Given below is a pedigree chart of a family with five
children. It shows the inheritance of attached ear lobes
as opposed to the free ones. Which of the following
condition can be drawn?
(a)
(b)
(c)
(d)
Parents are heterozygous
Parents are homozygous recessive
Parents are homozygous dominant
All are incorrect
(a)
(b)
(c)
(d)
formation of RBCs
formation of WBCs and platelets
coagulation of blood
anticoagulation
130 Sickle-cell anaemia is an autosomal linked recessive
trait that can be transmitted from parents to the
offspring when both the partners are carriers for all
the genes or heterozygous.
The disease is controlled by a single pair of allele,
Hb A and HbS . Identify X, Y and Z.
GAG
Normal Hb (A) Gene
123 Colour blindness in humans
mRNA
(a) results in defect in either red or green cone of eyes
(b) is caused due to the mutation in gene found on
X-chromosome
(c) affects males more frequently than females
(d) All of the above
GAG
Val
His
Leu
Thr
Pro
Glu
Glu
1
2
3
4
5
6
7
HbA
124 A woman has an X-linked condition on one of her
X-chromosomes. This chromosome can be inherited by
Peptide
Sickle-cell Hb (S) Gene
NEET 2018
(a) Only grand children
(c) Only daughters
CTC
X
Y
(b) Only sons
(d) Both (b) and (c)
mRNA
Z
125 A normal-visioned man whose father was colourblind,
marries a woman whose father was also colourblind.
They have their first child as a daughter. What are the
chances that this child would be colourblind?
(a) 100%
(c) 25%
(b) 0%
(d) 50%
CBSE-AIPMT 2012
Val
His
Leu
Thr
Pro
Val
Glu
1
2
3
4
5
6
7
HbS
Peptide
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106
X
(a) GTG
(b) CAC
(c) GTA
(d) GTC
Y
CAC
CTC
GAG
GAC
Z
Val (GUG)
Val (GUG)
Val (GUG)
Val (GUG)
139 A disease caused by an autosomal primary
non-disjunction is
(a) Down’s syndrome
(c) Turner’s syndrome
140 Karyotype of Down’s syndrome has how many
131 In sickle-cell anaemia,
chromosomes?
(a) Both parents are heterozygous carriers, but are
unaffected
(b) Single pair of allele controls the disease
(c) Only Hb s Hb s show diseased phenotype
(d) All of the above
132 In individual suffering from phenylketonuria,
(a)
(b)
(c)
(d)
enzyme phenylalanine hydroxylase is absent
phenylalanine do not convert to tyrosine
phenylpyruvic acid is formed
All of the above
133 Thalassemia in humans
(a) is an autosome linked recessive blood disorder
(b) can transmit from parents to offspring when both
parents are unaffected carriers (heterozygous)
(c) caused due to the mutation or deletion of one of the α
or β-globin chain
(d) All of the above
134 α-thalassemia in humans is controlled by
(a) HBA1 and HBA2 genes on chromosome 16
(b) HBA1 gene on chromosome 12
(c) HBA2 gene on chromosome 11
(d) HBA1 and HBA2 genes on chromosome 9
(a) 43
141
I.
II.
III.
IV.
(b) 46
Short statured body with small round head.
Furrowed tongue and partially opened mouth.
Palm is broad with characteristic palm crease.
Slow physical, psycomotor and mental development.
These are the characters of
(a) Down’s syndrome
(b) Turner’s syndrome
(c) Klinefelter’s syndrome (d) Edward syndrome
142 Choose the correct pair.
(a) Gynacoemastia – Development of breasts
(b) Turner’s syndrome – Loss of an X-chromosome in
females
(c) Polyploidy – Seen in plants
(d) All of the above
143 What is the genetic disorder in which an individual
has an overall masculine development gynaecomastia
and is sterile?
NEET (National) 2019
(a)
(b)
(c)
(d)
XX egg and Y from sperm
XX egg and XY sperm
X egg and XY sperm
Both (a) and (c)
145 In which genetic condition, each cell in the affected
person, has three sex chromosomes XXY?
NEET (Odisha) 2019
136 Failure of segregation of chromatid during cell
(a) Thalassemia
(c) Phenylketonuria
division cycle results in the gain or loss of
chromosome which as called
(b) hypopolyploidy
(d) polyploidy
plant brought from the field. He tells his teacher that
this cell is not like other cells at telophase stage.
There is no formation of cell plate and thus the cell is
containing more number of chromosomes as
compared to other dividing cells. This would result in
NEET 2016
polyploidy
somaclonal variation
polyteny
aneuploidy
(a) trisomy
(c) gene mutation
JIPMER 2018
(b) normal diploid
(d) None of these
(b) Klinefelter’s syndrome
(d) Turner’s syndrome
146 Monosomy and trisomy are represented respectively as
137 A cell telophase stage is observed by a student in a
138 Non-disjunction in meiosis results in
(d) 45
144 Klinefelter’s syndrome results from
(a) HBA2 gene on chromosome 16
(b) HBB gene on chromosome 11
(c) HBA1 gene on chromosome 15
(d) HBA1 and HBA2 gene on chromosome 8
(a)
(b)
(c)
(d)
JIPMER 2019
(c) 47
(a) Klinefelter’s syndrome (b) Edward syndrome
(c) Down’s syndrome
(d) Turner’s syndrome
135 β-thalassemia in humans is controlled by
(a) aneuploidy
(c) hyperpolyploidy
NEET 2017
(b) Klinefelter’s syndrome
(d) Sickle-cell anaemia
(a) n − 1, n + 2
(c) 2n − 1, 2n + 1
(b) 2n + 2, 2n + 1
(d) 2n − 2, 2n + 1
147 Female suffering from Turner’s syndrome possess
(a) 45 + XO
(b) rudimentary ovaries
(c) lack of secondary sexual characters
(d) All of the above
148 Which of the following are chromosomal disorders.
I. Colour blindness
II. Down’s syndrome
III. Phenylketonuria IV. Turner’s syndrome
V. Thalassaemia
(a) I, II and III
(c) III, IV and V
(b) II, IV and V
(d) II and IV
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CHAPTER 05 > Principles of Inheritance and Variation
NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
■ Direction (Q. No. 149-163) In each of the following
questions, a statement of Assertion (A) is given followed
by corresponding statement of Reason (R). Of the
statements, mark the correct answer as
(a) If both A and R are true and R is the correct
explanation of A
(b) If both A and R are true, but R is not the correct
explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true
149 Assertion (A) Offspring have characteristics of both
150
151
152
153
154
155
156
157
the parents.
Reason (R) Characters pass from the parents to their
progeny.
Assertion (A) True breeding lines have stable trait
inheritance for several generations.
Reason (R) Mendel conducted cross-pollination
experiments on true breeding lines.
Assertion (A) In F2 -generation, the traits seen in the
progeny were identical to their parents.
Reason (R) The progeny of the F2 -generation show
no blending of traits.
Assertion (A) Genes are not passed on from one
generation to the next.
Reason (R) Genes serves as the units of inheritance.
Assertion (A) Gametes receives only one allele of a
gene.
Reason (R) Mitosis occurs during gamete formation
leading to the formation of haploid gametes.
Assertion (A) In codominance, the F1 -generation
resembles both the parents.
Reason (R) An example is different type of red blood
cells that determine ABO blood grouping in humans.
Assertion (A) Behaviour of chromosome is parallel
to gene.
Reason (R) Genes are located on the chromosome.
Assertion (A) Some genes tend to pass together from
one generation to another.
Reason (R) Such genes are located for away from
each other on a chromosome.
Assertion (A) Insects show female heterogamety.
Reason (R) In insects, males have XO sex
chromosome and females have XX sex
chromosome.
158 Assertion (A) The mechanism of sex-determination
in honeybee is called haplodiploidy.
Reason (R) Female honeybees are haploid while male
honeybees are diploid.
159 Assertion (A) The non-allelic genes for red hair and
prickles are usually inherited together.
AIIMS 2018
Reason (R) The genes for red hair and prickles are
located on the same chromosome in close
association.
160 Assertion (A) Down’s syndrome, Klinefelter’s
syndrome and Turner’s syndrome are chromosomal
disorders.
Reason (R) In Klinefelter’s syndrome females are
AIIMS 2019
sterile.
161 Assertion (A) Phenylketonuria is recessive hereditary
disease caused by body’s failure to oxidise an amino
acid phenylalanine to tyrosine, because of defective
enzyme.
AIIMS 2018
Reason (R) It is characterised by in the presence of
phenylalanine acid in urine.
162 Assertion (A) Sickle-cell anaemia is an autosome
linked recessive trait.
Reason (R) It is controlled by a single pair of allele.
163 Assertion (A) Down’s syndrome is a Mendelian
disorder.
Reason (R) It is caused due to the presence of an
additional copy of chromosome 21.
II. Statement Based Questions
164 Which of the following statement is not true for two
genes that show 50% recombination frequency?
NEET 2013
(a) The genes may be on different chromosomes
(b) The genes are tightly linked
(c) The genes show independent assortment
(d) If the genes are present on the same chromosome, they
undergo more than one cross overs in every meiosis
165 In Antirrhinum (Snapdragon), a red flower was
crossed with a white flower and in F1 -generation, pink
flowers were obtained.
When pink flowers were selfed, the F2 -generation
showed white, red and pink flowers. Choose the
incorrect statement from the following.
NEET (National) 2019
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108
(a) Pink colour in F1 is due to incomplete dominance
1
2
1
(b) Ratio of F 2 is (Red) : (Pink) : (White)
4
4
4
(c) Law of segregation does not apply in this experiment
(d) This experiment does not follow the principle of
dominance
166 Select the incorrect statement. NEET (National) 2019
(a) In male grasshoppers, 50% of sperms have no
sex-chromosome
(b) In domesticated fowls, sex of progeny depends on the
type of sperm rather than egg
(c) Human males have one of their sex-chromosomes much
shorter than the other
(d) Male fruitfly is heterogametic
167 Which one of the following conditions correctly
describes the manner of determining the sex?
AIIMS 2018
(a) Homozygous sex chromosomes (ZZ) determine female
sex in birds
(b) XO type of sex chromosomes determine male sex in
grasshopper
(c) XO condition in humans as found in Turner’s syndrome
determines female sex
(d) Homozygous sex-chromosomes (XX) produce males in
Drosophila
168 The following statements are regarding sex-
determination. Choose the incorrect one.
(a) There are two types of sex-determining mechanism
(b) In male heterogamety, male has autosomes and sex
chromosome XY
(c) In female heterogamety, it has autosomes and one Z
and one W chromosomes
(d) Female heterogamety is found in mammals
169 Which of the following statement is incorrect?
(a) X-body of Henking was given the name
X-chromosomes
(b) In many insects, all eggs bear an additional
X-chromosomes besides autosomes
(c) X-chromosomes is a sex chromosomes as it is involved
in sex-determination
(d) None of the above
170 Identify the incorrect statement for sex-determination
in humans.
(a)
(b)
(c)
(d)
Humans contain 23 pairs of autosomes
Females produce only one type of ovum
Genetic makeup of sperm determine the sex of the child
In males, two types of gametes are produced
171 Which among the following statement is not true for
haemophilia?
(a) It is a sex-linked dominant disease
(b) It is transmitted to unaffected carrier female to male
progeny
(c) The possibility of a female becoming a haemophilic is
extremely rare
(d) The family pedigree of Queen Victoria shows a number
of haemophilic descendents
172 Thalassemia and sickle-cell anaemia are caused due
to a problem in globin molecule synthesis. Select the
correct statement.
(a) Both are due to a qualitative defect in global chain
synthesis
(b) Both are due to a quantitative defect in globin chain
synthesis
(c) Thalassemia is due to the synthesis of abnormal
haemoglobin molecules
(d) None of the above
173 Select the incorrect statement.
(a) RBCs become sickle-shaped under low oxygen tension
in sickle-cell anaemia
(b) Phenylpyruvic acid gets accumulated in brain and
excreted in urine due to poor absorption by kidney
(c) In thalassemia, α and β-globin chains are altogether
absent in body
(d) Thalassemia is an autosome linked recesive disease
174 Which of the following statement is correct with
respect to monohybrid and dihybrid cross?
(a) A monohybrid cross is performed for one generation
whereas dihybrid cross is performed for two generations
(b) A monohybrid cross involves a single parent, whereas a
dihybrid cross involved two parents
(c) A monohybrid cross produces a single progeny whereas
a dihybrid cross produce two progenies
(d) A monohybrid cross involves individuals with one
heterozygous character, whereas a dihybrid corss
involves individuals with two heterozygous characters
175 Which of the following statement(s) is/are correct
with respect to the law of segregation?
(a) Alleles do not show blending
(b) The paired factors or alleles segregate from each other
such that a gamete receives the two factors as in the
original paired form
(c) Homozygous parent produce similar types of gametes
whereas heterozygous ones produce two types of
gametes each having one allele with unequal proportion
(d) All of the above
176 Which of the following statement(s) is/are true with
respect to sickle-cell anaemia?
(a) The mutant haemoglobin of sickle-cell anaemic
individual undergo polymerisation under low oxygen
tension causing sicking of RBCs
(b) Sickle-cell anaemia occur due to the single base
substitution (GAG → GUG) at the sixth codon of
β-globin gene
(c) Individuals heterozygous for sicke-cell anaemia
( Hb SHb A ) are resistant towards malaria
(d) All of the above
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CHAPTER 05 > Principles of Inheritance and Variation
177 Which of the following statement is incorrect?
(a) Mutations provide variations on which natural selection
acts
(b) The vast majority of mutations produce dominant
alleles
(c) Mutations arise spontaneously, infrequently and
randomly
(d) Rate of mutation can be increased by artificial means
178 Read the following statements.
I. Mendelian factors are now called genes.
II. Characters blend in homozygous condition only.
III. All characters in human show dominance.
IV. Hugo de Vries was involved in rediscovery of
Mendel’s works.
Which of the above statements are true?
(a) I and II
(c) I and IV
(b) II and III
(d) IV and III
179 Which of the following is true about linkage ?
I. It is phenomenon in which more recombinants are
produced in F2 -generation.
II. More parental combinations are produced in
F 2 -generation.
III. Genotype which are present in F1 hybrid, reappear in
high frequency in F2 -generation.
IV. It is a phenomenon in which two chromosomes are
linked.
182 Consider the following statements regarding ABO
blood group in human.
I. It is controlled by multiple alleles.
II. It shows codominance.
III. Codominance can be manifested phenotypically in
human.
IV. It follows the Mendel’s law of inheritance.
Which of the statments(s) given above are correct?
(a) Only I
(c) II and III
(b) I and II
(d) IV and II
183 Consider the following statements.
I. 100% parental combinations are found in
F 2 -generation.
II. F 2 phenotypic ratio is 3 : 1 in dihybrid cross.
III. Dihybrid test cross ratio is 1 : 1 inF 2 -generation.
IV. Linked genes tends to separate frequently.
Which of the statement given above are correct?
(a) I, II and IV
(c) II, III and IV
(b) I, III and IV
(d) I and II
184 Select the incorrect statement(s) from the options
Choose the correct option.
given below with respect to dihybrid cross. AIIMS 2018
I. Tightly linked genes on the same chromosome show
higher recombinations.
II. Genes far apart on the same chromosome show very
few recombinations.
III. Genes loosely linked on the same chromosome show
similar recombinations.
(a) Only I
(c) I and III
(a) I and II
(c) I and III
(b) Only II
(d) III and IV
180 Which of the following statements are false?
I. A dominant allele determines the phenotype when
paired with a recessive allele.
II. A recessive allele is weaker than a dominant allele.
III. A recessive allele do not shows its effects when paired
with a dominant allele.
IV. A dominant allele is always better for an organism.
(a) II, I and IV
(c) I, II and III
(b) II, III and IV
(d) I, III and IV
181 Which of the following statements are false?
I. Specific mutations are acquired and occur only when
required.
II. Inheritance of specific trait can be determined using
pedigree analysis.
III. Like recombination, mutations cause variations in the
DNA sequence.
IV. Chromosomal aberrations are observed in cancer cells
randomly irrespective of the alleles present.
Choose the correct option.
(a) II and III
(c) II, III and IV
(b) Only I
(d) I, II and IV
(b) III and II
(d) All of these
185 Consider the following statements and select the
statement(s) which are correct with respect to the
reasons as to why Mendel could not find out about
linkage?
I. Some genes are linked, but they are too far apart for
crossing over to be distinguished from independent
assortment.
II. Linked genes, were never tested for the same time in
same cross.
III. All seven genes, were present on the same
chromosomes.
IV. All seven genes were present on 4 chromosomes, but
they were present far apart.
(a) I and II
(c) III and IV
(b) II and III
(d) Only IV
186 Consider the following statement and select the
statements which are correct with respect to the
reasons as to why Mendel’s work remain
unrecognised for a long time.
I. Communication was not easy.
II. Concept of factors which did not blend was not
accepted.
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110
III. Use of mathematics to explain biological problem was
unacceptable.
IV He could not provide any physical proof for the
existance of factors.
(a) I and II
(c) III and IV
(b) II and III
(d) All of these
187 Consider the following statements.
I. Henking found specific nuclear structures through
spermatogenesis in the 50% sperms of few insects.
II. The sex-determination in honeybee is based on the
number of sets of chromosomes an individual receives.
Select the correct option.
188 Which of the following statements are correct reasons
for why fruitfly is excellent model for genetics?
I. Small life cycle (two week).
II. Can be feed on simple synthetic medium.
III. Single mating produce large number of progeny.
IV. Clear differentiation of sexes.
V. Many heredity variation can be seen with low power
microscopes.
Choose the correct option.
(b) I, III and IV
(d) I and IV
III. Matching Type Questions
Column I
(Genetic crosses)
Select the correct option.
(b) I is false, II is true
(d) Both I and II are false
190 Consider the following statements.
I. The number of chromosomes in male and female
insects is same.
II. The female insects are heterozygous while male insect
is homozygous.
Column II
(Phenotypic ratios)
A. Test cross
1.
9:3:3:1
B. Monohybrid cross
2.
1:1
C. Dihybrid cross
3.
3:1
Codes
A
(a) 2
(c) 3
B
1
2
C
3
1
A
(b) 2
(d) 1
B
3
3
C
1
2
194 Match the following columns.
(b) III, IV and V
(d) All of these
189 Consider the following statements.
I. The crosses carried out by Morgan on Drosophila were
sex-linked dihybrid crosses.
II. The F2 -ratio in Morgan’s experiment deviated
significantly from 9 : 3 : 3 : 1 ratio.
(a) I is true, II is false
(c) Both I and II are true
(a) II and IV
(c) I, II and III
193 Match the following columns.
(a) Both I and II are true (b) I is true, II is false
(c) Both I and II are false (d) I is false, II is true
(a) I, II and III
(c) I, IV and V
192 Pick out the correct statements.
NEET 2016
I. Haemophilia is a sex-linked recessive disease.
II. Down's syndrome is due to aneuploidy.
III. Phenylketonuria is an autosomal recessive gene
disorder.
IV. Sickle-cell anaemia is an X - linked recessive gene
disorder.
Column I
(Chromosomal
abberation)
AIIMS 2019
Column II
(Features)
A. Inversion
1.
Change in linear order of genes
by 180º rotation
B. Duplication
2.
Loss of part of chromosome
C. Deletion
3.
Addition of part of chromosome
so that it is represented twice
D. Translocation
4.
Shifting of a part of chromosome
to another non-homologous
chromosome
Codes
A
(a) 1
(c) 1
B
2
3
C
3
2
D
4
4
(b)
(d)
A
4
2
B
3
1
C
2
4
D
1
3
195 Match the following columns.
Select the correct option.
(a) I is true, II is false
(c) I is false, II is true
Column I
(Genetic interactions)
(b) Both I and II are true
(d) Both I and II are false
191 Consider the following statements.
I. Both colour blindness and haemophilia are sex-linked
recessive traits.
II. In sex-linked recessive traits, heterozygous or carrier
female transmit disease to sons.
Select the correct option.
(a) Both I and II are true (b) I is true, II is false
(c) Both I and II are false (d) I is false, II is true
Column II
(Genetic cross ratios)
A. Incomplete dominance
1.
12 : 3 : 1
B. Dominant epistasis
2.
1:2:1
C. Recessive epistasis
3.
9:7
D. Complementary genes
4.
9:3:4
Codes
A
(a) 2
(c) 3
B
1
4
C
4
1
D
3
2
A
(b) 1
(d) 4
B
2
3
C
3
2
D
4
1
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CHAPTER 05 > Principles of Inheritance and Variation
199 Match the following columns.
196 Match the following columns.
Column I
(Scientists)
Column I
Column II
(Discoveries)
Column II
A.
Non-parental gene exchange
1.
Crossing over
Non-sister chromatids
2.
X and Y
A.
Gregor Mendel
1.
Chromosomal theory of
inheritance
B.
C.
Sex chromosome
3.
Polyploidy
B.
Sutton and Boveri
2.
Law of inheritance
D.
More than two sets of
chromosomes
4.
Recombination
C.
Henking
3.
Linkage
D.
Morgan
4.
Discovered X-body
E.
de Vries
5.
Mutation
Codes
A
(a) 4
(b) 2
(c) 4
(d) 2
B
2
1
1
3
C
1
4
5
4
D
3
3
3
5
Codes
A
(a) 4
(c) 2
D
3
1
A
(b) 2
(d) 2
Column I
Column II
ABO blood groups
1.
Dihybrid cross
B.
Law of segregation
2.
Monohybrid cross
C.
Law of independent
assortment
3.
Base pairs
substitution
D.
Gene mutation
4.
Multiple allelism
1.
Codominance.
2.
Change in nucleotides
C.
Epistasis
3.
One gene shows multiple
phenotypic expression
D. Mutation
4.
Non-allelic gene inheritance
Codes
A
(a) 1
(c) 3
B
2
1
C
3
4
D
4
2
(b)
(d)
A.
Dominance
1. Many genes govern a single character
B.
Codominance
2. In a heterozygous organism only
one allele expresses itself
C.
Pleiotropy
3. In a heterozygous organism both
alleles express themselves fully
D.
Polygenic
inheritance
4. A single gene influences many
characters
B
1
3
3
1
C
2
4
1
4
D
3
1
2
3
B
3
3
C
4
4
D
1
2
NEET (Odisha) 2019
Column II
A.
XX-XO method of
sex-determination
1. Turner’s syndrome
B.
XX-XY method of
sex-determination
2. Female heterogamety
C.
Karyotype-45
3. Grasshopper
D.
ZW-ZZ method of sexdetermination
4. Female homogamety
NEET 2016
Column II
(Description)
A
2
1
201 Match the items of Column I with Column II.
198 Match the terms in Column I with their description in
Column II and choose the correct option.
AIIMS 2019
B.
D
3
1
3
3
Column I
(Terms)
D
3
3
Both alleles express equally
Column I
C
4
4
2
1
C
4
1
Column II
A. Pleiotropic gene
A.
B
1
3
1
2
B
1
4
option from the codes given below.
Column I
Codes
A
(a) 4
(b) 2
(c) 4
(d) 2
C
2
3
200 Match the following columns and choose the correct
E
5
5
2
1
197 Match the following columns.
Codes
A
(a) 2
(b) 2
(c) 4
(d) 4
B
1
4
Codes
A
(a) 2
(c) 3
B
4
4
C
1
1
D
3
2
A
(b) 1
(d) 4
B
4
2
C
2
1
D
3
3
202 Match the following columns.
Column II
(Chromosome complement)
A.
Column I
(Animals)
Fruitfly
1.
2n = 6 + XY
B.
Fowl
2.
2n = 14 + XX
C.
Grasshopper
3.
2n = 16 + XO
D.
Human
4.
2n = 44 + XY
Codes
A
(a) 1
(c) 3
B
2
4
C
3
1
D
4
2
A
(b) 2
(d) 2
B
3
1
C
4
4
D
1
3
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112
203 Match the following columns.
Column I
(Pedigree symbols)
A.
1.
Column II
(Refers to)
Death
B.
2.
Five unaffected offspring
C.
5
3.
Sex unspecified
D.
5
4.
Female
5.
Male
E.
Codes
A
(a) 1
(b) 1
(c) 1
(d) 5
B
2
2
2
4
C
5
4
3
3
D
4
3
4
2
E
3
5
5
1
204 Match the following columns.
A.
B.
C.
D.
E.
Column I
(Types of polyploid)
Monoploidy
Monosomy
Nulisomy
Trisomy
Tetrasomy
1.
2.
3.
4.
5.
Column II
(Chromosomes constitution)
2 n–1
2 n+1
2 n+2
2 n–2
n
Codes
A
B
C
D
E
(a) 2
1
3
4
5
(b) 5
2
4
1
3
(c) 1
5
3
4
2
(d) 5
1
4
2
3
205 Match the following columns.
Column I
(Genetical trait)
Column II
(Name of disorders)
A.
Autosomal linked recessive trait
1. Down’s syndrome
B.
Sex-linked recessive disease
2. Phenylketonuria
C.
Inborn metabolic error linked to
autosomal recessive trait
3. Haemophilia
D.
Additional 21st chromosome
4. Sickle-cell anaemia
Codes
A
(a) 3
B
4
C
1
D
2
(b) 4
(c) 2
(d) 4
1
1
3
2
4
2
3
3
1
NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
206 Which of the following is/are Mendelian disorder?
(a) Thalassemia
(c) Phenylketonuria
(b) Cystic fibrosis
(d) All of these
207 All genes located on the same chromosome
(a) form different groups depending upon their relative
distance
(b) form one linkage group
(c) will not form any linkage group
(d) form interactive groups that affect the phenotype
208 A cross between two tall plants resulted in offspring
having few dwarf plants. What would be the
genotypes of both the parents?
(a) TT and Tt (b) Tt and Tt (c) TT and TT (d) Tt and tt
209 In a dihybrid cross, if you get 9 : 3 : 3 : 1 ratio it
denotes that
(a) the alleles of two genes are interacting with each
other
(b) it is a multigenic inheritance
(c) it is a case of multiple allelism
(d) the alleles of two genes are segregating independently
210 In the F2 -generation of a Mendelian dihybrid cross
the number of phenotypes and genotypes are
(a) phenotypes-4, genotypes-16
(b) phenotypes-9, genotypes-4
(c) phenotypes-4, genotypes-8
(d) phenotypes-4, genotypes-9
211 Two genes ‘A’ and ‘B’ are linked. In a dihybrid cross
involving these two genes, the F1 heterozygote is
crossed with homozygous recessive parental type (aa
bb). What would be the ratio of offspring in the next
generation?
(a) 1 : 1 : 1 : 1
(b) 9 : 3 : 3 : 1
(c) 3 : 1
(d) 1 : 1
212 Mendel’s law of independent assortment holds good
for genes situated on the
(a) non-homologous chromosomes
(b) homologous chromosomes
(c) extra nuclear genetic element
(d) same chromosome
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CHAPTER 05 > Principles of Inheritance and Variation
213 It is said that Mendel proposed that the factor
controlling any character is discrete and independent.
This proposition was based on the
(a ) results of F3 -generation of a cross
(b) observations that the offspring of a cross made between
the plants having two contrasting characters shows only
one character without any blending
(c) self-pollination of F1 offsprings
(d) cross-pollination of F1 -generation with recessive parent
214 Occasionally, a single gene may express more than
one effect. The phenomenon is called
(a) multiple allelism
(b) mosaicism
(c) pleiotropy
(d) polygeny
215 Person having genotype I A I B would show the blood
group as AB. This is because of
(a) pleiotropy
(b) codominance
(c) segregation
(d) incomplete dominance
216 Mother and father of a person with ‘O’ blood group
have ‘A’ and ‘B’ blood group, respectively. What
would be the genotype of both mother and father?
(a) Mother is homozygous for ‘A’ blood group and father is
heterozygous for ‘B’
(b) Mother is heterozygous for ‘A’ blood group and father
is homozygous for ‘B’
(c) Both mother and father are heterozygous for ‘A’ and ‘B’
blood group, respectively
(d) Both mother and father are homozygous for ‘A’ and ‘B’
blood group, respectively
217 Distance between the genes and percentage of
recombination shows
(a) a direct relationship
(b) an inverse relationship
(c) a parallel relationship
(d) no relationship
218 ZZ/ZW type of sex-determination is seen in
(a) platypus
(b) snails
(c) cockroach
(d) peacock
219 In a certain taxon of insects some have 17
chromosomes and the others have 18 chromosomes.
The 17 and 18 chromosome-bearing organisms are
(a) males and females, respectively
(b) females and males, respectively
(c) all males
(d) all females
220 The inheritance pattern of a gene over generations
among humans is studied by the pedigree analysis.
Character studied in the pedigree analysis is
equivalent to
(a) quantitative trait
(b) Mendelian trait
(c) polygenic trait
(d) maternal trait
221 If a genetic disease is transferred from a
phenotypically normal, but carrier female to only
some of the male progeny, the disease is
(a) autosomal dominant
(b) autosomal recessive
(c) sex-linked dominant
(d) sex-linked recessive
222 In sickle-cell anaemia glutamic acid is replaced by
valine. Which one of the following triplet codes for
valine?
(a) G G G
(c) G A A
(b) A A G
(d) G U G
223 Conditions of a karyotype 2n ± 1 and 2n ± 2 are called
(a) aneuploidy
(b) polyploidy
(c) allopolyploidy
(d) monosomy
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114
Answers
‡ Mastering NCERT with MCQs
1
11
21
31
41
51
61
71
81
91
101
111
121
131
141
(c)
(c)
(c)
(b)
(c)
(b)
(b)
(a)
(d)
(a)
(c)
(c)
(d)
(d)
(a)
2
12
22
32
42
52
62
72
82
92
102
112
122
132
142
(b)
(c)
(b)
(c)
(b)
(c)
(b)
(b)
(a)
(d)
(a)
(d)
(a)
(d)
(d)
3
13
23
33
43
53
63
73
83
93
103
113
123
133
143
(a)
(a)
(a)
(a)
(d)
(b)
(d)
(b)
(a)
(c)
(b)
(d)
(d)
(d)
(a)
4
14
24
34
44
54
64
74
84
94
104
114
124
134
144
(a)
(a)
(a)
(b)
(a)
(c)
(a)
(c)
(d)
(a)
(a)
(d)
(d)
(a)
(d)
5
15
25
35
45
55
65
75
85
95
105
115
125
135
145
(a)
(c)
(a)
(a)
(d)
(a)
(d)
(a)
(a)
(c)
(d)
(a)
(b)
(b)
(b)
6
16
26
36
46
56
66
76
86
96
106
116
126
136
146
(d)
(b)
(b)
(c)
(a)
(b)
(b)
(b)
(c)
(a)
(a)
(d)
(a)
(a)
(c)
7
17
27
37
47
57
67
77
87
97
107
117
127
137
147
(a)
(a)
(d)
(a)
(b)
(a)
(a)
(d)
(d)
(d)
(b)
(a)
(a)
(a)
(d)
8
18
28
38
48
58
68
78
88
98
108
118
128
138
148
(c)
(a)
(d)
(b)
(d)
(a)
(a)
(b)
(a)
(d)
(d)
(b)
(a)
(a)
(b)
9
19
29
39
49
59
69
79
89
99
109
119
129
139
(a)
(c)
(c)
(c)
(a)
(a)
(d)
(b)
(c)
(d)
(b)
(a)
(c)
(a)
10
20
30
40
50
60
70
80
90
100
110
120
130
140
(b)
(a)
(c)
(d)
(a)
(a)
(b)
(b)
(d)
(b)
(c)
(c)
(a)
(c)
(d)
(b)
(c)
(b)
(c)
(a)
153
163
173
183
193
203
(c)
(d)
(c)
(d)
(b)
(d)
154
164
174
184
194
204
(a)
(b)
(d)
(d)
(c)
(d)
155
165
175
185
195
205
(b)
(c)
(a)
(a)
(a)
(d)
156
166
176
186
196
(c)
(b)
(d)
(d)
(b)
157
167
177
187
197
(d)
(b)
(b)
(a)
(d)
158
168
178
188
198
(c)
(d)
(c)
(d)
(b)
‡ NEET Special Types Questions
149
159
169
179
189
199
(a)
(a)
(d)
(a)
(c)
(a)
150
160
170
180
190
200
(b)
(c)
(a)
(b)
(d)
(c)
151
161
171
181
191
201
(a)
(b)
(a)
(b)
(a)
(c)
152
162
172
182
192
202
‡ NCERT Exemplar Questions
206 (d)
216 (c)
207 (b)
217 (a)
208 (b)
218 (d)
209 (d)
219 (a)
210 (d)
220 (b)
211 (d)
221 (d)
212 (b)
222 (d)
213 (b)
223 (a)
214 (c)
215 (b)
Answers & Explanations
Answers & Explanations
5 (a) Mendel performed his hybridisation experiment on
Pisum sativum (garden pea) for 7 years between 1856-1863.
6 (d) Mendel investigated characters in the garden pea plant
that were manifested as two opposite traits, e.g. tall or dwarf
plants, yellow or green seeds. This allowed him to set up a
basic framework of rules governing inheritance, which was
expanded on by later scientists to account for all the diverse
natural observations and the complexity inherent in them.
7 (a) A true breeding line is one that have undergone
continuous self-pollination, shows stable trait inheritance
and expression for several generations.
9 (a) Mendel selected 7 dominant traits and 7 recessive traits
out of the total 14 traits or 7 opposing pairs of traits. The
traits have been tabulated below
Characters
Dominant traits
Recessive traits
Seed shape
Round
Wrinkled
Seed colour
Yellow
Green
Flower colour
Violet
White
Pod shape
Inflated
Constricted
Pod colour
Green
Yellow
Flower position
Axial
Terminal
Stem height
Tall
Dwarf
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CHAPTER 05 > Principles of Inheritance and Variation
These are formed when epidermal cells become
glandular and hair like, called as trichomes. This
character was not amongst the seven pairs of characters
of the pea plant. Mendel selected for his hybridisation
experiments.
19 (c) In Mendel’s experiment dominant and recessive
traits were expressed or appeared separately. This
shows that there was no mixing of characters, thus
non-blending of character in F2 -generations is observed.
22 (b) Option (b) is incorrect and can be corrected as
The genetic composition of an organism, with respect
to one or more characters whether the gene is expressed
or not is called genotype.
36
37
38
23 (a) The formula to calculate the number of gametes
from a given genotype is 2n .
Where, n = number of heterozygosity in the given
genotype. Thus, number/types of gametes produced by
a homozygous individual of genotype AA is 2(0) = 1 and
by heterozygous individual of genotype Aa is 2(1) = 2.
40
27 (d) Monohybrid cross with incomplete dominance
shows the same genotypic and phenotypic ratio, i.e.
1 : 2 : 1, as depicted by the cross given below
AA
Red
aa
White
A
a
Parents
41
Aa
Pink
F1-generation
a
A
Gametes
Gametes
42
a
Aa A
a
Pink
A
aa
AA
Red White
Aa
Pink
F2-generation
Genotypic ratio – 1 (AA) : 2 (Aa) : 1 (aa)
Phenotypic ratio – 1 (Red) : 2 (Pink) : 1 (White)
28 (d) Since, both the male and female parents are
homozygous with genotype TT and tt, respectively they
will contribute only one type of gamete. The male will
produce gamete (pollen) of type T and the female will
produce a gamete (egg) of type t.
31 (b) Mendel performed test cross to know the genotype
of F2 . Test cross involves a cross between dominant F2
plant with the homozygous recessive parent plant. The
ratio of monohybrid test cross is 1 : 1 between Tt and tt.
So, if the ratio of test cross comes as mentioned, then
the F2 genotype is heterozygous tall and if it deviates
from this, then the F2 genotype is homozygous tall.
34 (b) 3:1 ratio in F2 -generation can be explained by the
law of dominance. It states that, only dominant allele
shows its effect even in the heterozygous condition and
masks the effect of recessive allele. In the given ratio, 3
represents the dominant phenotype, while 1 represents
the recessive phenotype.
(c) Mendel’s principle of segregation means that the
germ cells (gametes) always receive either one allele of
father or one allele of mother. The law of segregation
states that, hereditary characters in the form of allele
segregate from each other during the formation of
gametes. Half of the gametes carry one allele and other
half carry other allele for a character.
(a) Law of purity of gametes states that the characters
which were hidden or masked in F1 progeny get
recovered in the progeny of F2 -generation.
(b) Option (b) is correct as the ratio of 3 : 1 helped to
deduce law of dominance and law of segregation.
Whereas law of independent assortement was deduced
by Mendel by performing dihybrid cross ( 9 : 3 : 3 : 1).
Incomplete dominance was not deduced by Mendel.
(d) In incomplete dominance, the two genes of an
allelomorphic pair are not related as dominant or
recessive but each of them express themselves partially.
In this phenomenon, one allele may function normally
and the other may either function normally, may be
non-functional or may perform normally, but with less
efficiency. This occurs due to some changes in the allele
which modifies the information present in it.
Thus, option (d) is correct.
(c) Both codominance and incomplete dominance give
an identical genotypic and phenotypic ratio of 1 : 2 : 1.
Codominance and incomplete dominance differ in the
fact that in codominance both the alleles are dominant
and express themselves at the same time. But in
incomplete dominance, the two alleles are neither
dominant nor recessive to each other.
(b) On self-crossing TtRr plant, the following cross is
obtained
Tt Rr (heterozygous tall and pink)
↓ (self-crossed)
Tt Rr × Tt Rr
Gametes TR
Tr
tR
tr
TR
TTRR
(Tall red)
TTRr
(Tall pink)
TtRR
(Tall red)
TtRr
(Tall pink)
Tr
TTRr
TTrr
(Tall pink) (Tall white)
TtRr
(Tall pink)
Ttrr
(Tall white)
tR
TtRR
(Tall red)
ttRR
ttrR
(Dwarf red) (Dwarf pink)
tr
TtRr
Ttrr
ttRr
ttrr
(Tall pink) (Tall white) (Dwarf pink) (Dwarf white)
TtRr
(Tall pink)
Plants with pink flower = 8 = 50%
Plants with red flower = 4 = 25%
Plants with white flower = 4 = 25%
Tall plants = 75%
Dwarf plants = 25%
43 (d) Option (d) is correct as in codominance, both alleles
of a pair express themselves fully in F1 -generation, so it
resembles both the parents.
Answers & Explanations
10 (b) Trichomes are the epidermal tissues structure.
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Master The NCERT > BIOLOGY (Vol-II )
44 (a) The cross between red flowered and pink flowered
l
When only one parent is homozygous
plants of Mirabilis jalapa is depicted below
%
&
×
RR
Red
Rr
Pink
R
R
&
R
%
RR
R
Parents
r
r
l
Gametes
F1 - generation
Rr
Thus, the ratio of offspring produce would be
Red : Pink = 1 : 1
46 (a) The ABO blood groups are controlled by the
I-gene, which has three alleles (IA , IB, i).
47 (b) The plasma membrane of the red blood cells has
sugar polymers that protrude from its surface and the
kind of sugar is controlled by ‘I’ gene. It has three
alleles IA , IB and i. Out of these only two alleles IA and
IB produce a slightly different form of the sugar, while
allele i does not produce any sugar. Because humans are
diploid organisms, each person possesses any two of the
three I gene alleles. IA and IB are completely dominant
over i.
49 (a) AB blood group is characterised by the presence of
Answers & Explanations
l
both antigen A and B, i.e. IA and IB over the surface of
RBCs.
Phenotype AB
↓
Genotype IA IB
↓
Antigen A + Antigen B
Here, both alleles are able to express themselves
forming antigens A and B. This is called as
codominance, a phenomenon in which both the alleles
in a heterozygote are expressed.
50 (a) The possible genotype of parents, male with blood
group A and female with blood group B, having
progeny with either blood group AB or B is I A i (male) :
I BI B (female). It can be depicted by the cross given below
B
I i
A
I I
B
I AI B
Blood
group
AB
I Bi
Blood
group
B
I Bi
Blood
group
B
51 (b) Since, it has not been specified whether the parents
are homozygous or heterozygous for the alleles of gene
I the possible genotype of + and parent could be
I I
I i
Phenotype
A
B
B
or
&
A
B B
I i
I I
A
B
When both parents are homozygous
%
A A
&
Genotype
I I
I I
Phenotype
A
B
B B
When both parents are heterozygous
%
&
A
B
Genotype
I i
I i
Phenotype
A
B
Thus, when blood group of father is A and of mother is B,
then the blood group of progeny will be A, B, AB and O.
52 (c) A cross between a husband and wife one with AB
blood group and the other with A blood group will
produce four genotypes and three phenotypes. It has
been depicted by the cross given below
Husband
%
IA
IB
IA IA
IA IB
IA i
IB i
&
Wife
IA
i
Thus, the genotypes and the phenotypes of the offspring
would be
Genotypes : 4(IA IA , IA IB , IA i, IB i)
Phenotypes : 3 (A, B, AB)
53 (b) Dominance, codominance and multiple alleles are
the characteristics that represent ‘inheritance of blood
groups’ in humans. ABO blood groups are determined
by the gene I.
There are multiple (three) alleles; I A , I B and i of this
gene. Allele I A and I B are dominant over i. However,
when I A and I B alleles are present together, they show
codominance. Therefore, option (b) is correct.
55 (a) Option (a) is correct. This can be explained as
occasionally a single gene product may produce more
than one effect. Like in starch synthesis in pea seeds
controlled by one gene having two alleles (B and b).
Thus, the phenotype and genotype expressed are
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I AI B
Blood
group
AB
%
&
%
A A
Genotype
BB–round seed, large starch synthesis.
bb–wrinkled seed, less starch synthesis.
Bb–round seed, intermediate starch synthesis.
Thus, if we take size as a phenotype, allele B shows
complete dominance over ‘b’, but if we take starch
synthesis as a phenotype, allele B and b shows
incomplete dominance.
57 (a) The formula to determine the number of gametes is
2n = 2(2) = 4
Thus, RrYy would produce 4 gametes of the types RY,
Ry, rY, ry.
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59 (a) When plants bearing round yellow (RRYY) seeds
are crossed with plants bearing and wrinkled green
(rryy) seeds, all the plants in F1 -generation will have
yellow round seeds. It can be depicted by the cross
given below
%
&
RY
ry
rryy
RRYY
x
(Wrinkled, green)
(Round, yellow)
Parents
Gametes
69
RrYy
(Round, Yellow)
F1-generation
60 (a) A cross between pure yellow round seeded plants
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and pure green wrinkled seeded plants is shown below
Parents
(Wrinkled green)
rryy
RY
ry
Gametes
×
(Round yellow)
RRYY
74
(Round yellow)
RrYy
F1-generation
78
Selfing
RY
RY
Gametes
Gametes
rY
Ry
ry
RRYy
RrYy
F2-generation
RrYy
RRyy
rrYy
Rryy
ry
RRYy
rrYY
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Ry
RrYY
RrYY
RrYy
rY
RRYY
RrYy
rrYy
80
Rryy
rryy
Phenotypic ratio
Round yellow : Round green : Wrinkled yellow : Wrinkled green
9
:
3
:
3
:
1
Genotypic 1 (RRYY) : 2 (RRYy) : 2 (RrYY) : 4 (RrYy) : 1 (RRyy)
ratio
2 (Rryy) : 1 (rrYY) : 2 (rrYy) : 1(rryy)
Thus, the number of plants of F2 -generation having
yellow coloured seeds are 12 (out of 16).
64 (a) The genotypic ratio of a dihybrid cross is
1:2:2:4:1:2:1:2:1
Thus, we see that 9 different genotypes are observed in
the F2 -generation.
65 (d) In 1900, three scientists (de Vries, Correns and von
Tschermak) independently rediscovered Mendel’s
results on the inheritance of characters. Also, by this
time due to advancements in microscopy that were
85
taking place, scientists were able to carefully observe
cell division.
This led to the discovery of structures in the nucleus
that appeared to double and divide just before each cell
division.
(d) Sutton and Boveri proposed the chromosomal theory
of inheritance. In 1902, the chromosomal movement
during meiosis was worked out. Walter Sutton and
Theodore Boveri stated that pairing and separation of a
pair of chromosomes would lead to the segregation of a
pair of factors they carried. They united the knowledge
of chromosomal segregation with Mendelian principles
and called it chromosomal theory of inheritance.
(b) Both genes and chromosomes (Mendelian factors)
wheather dominant or recessive are transmitted from
generation to generation in the pure or unaltered form. It
is also called law of purity of gametes.
(c) The pair given in option (c) is incorrect. It can be
corrected as
TH Morgan – Linkage
de Vries – Mutation
Rest of the pairs are correct.
(b) When two genes in a dihybrid cross are situated on
the same chromosome, the proportion of the parental
gene combinations are much higher than the
non-parental or recombinant type as linked genes are
inherited together in offspring.
(b) Alfred Sturtevant was the first to explain the
concept of chromosomal mapping. It is constructed on
the basis of recombination frequency between gene
pairs on the same chromosome. This frequency is
directly proportional to the distance between these two
genes.
It can be used to determine the exact location of a gene
on the chromosome.
(b) In the construction of genetic maps, map unit or
centi Morgan is a unit or distance between genes on
chromosomes, representing 1% cross over,
i.e. 1 map unit = 1% cross over
Hence, the genetic distance between genes is based on
average number of cross over frequency between them.
(a) Since, genes A and B are more close than genes A
and C, therefore, gene A has to be present before genes
B and C with gene B present in between genes A and C.
Other options are incorrect and can be corrected as
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Gene C is not between genes A and B.
More crosses have occurred between A and C than A
and B.
88 (a) Human skin colour is another classic example for
polygenic trait the phenotype reflects the contribution of
each allele, i.e. the effect of each allele is additive. To
understand this better let us assume that three genes, i.e.
A, B and C control skin colour in human with the
dominant forms A, B and C responsible for dark skin
colour and the recessive forms a, b and c for light skin
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Answers & Explanations
CHAPTER 05 > Principles of Inheritance and Variation
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101
colour. The genotype with all the dominant alleles
(AABBCC) will have the darkest skin colour and that
with all the recessive alleles (aabbcc) will have the
lightest skin colour.
(c) In the given pairs, option (c) is wrongly matched. It
can be corrected as
Starch synthesis in pea is an example of pleiotropy.
Rest of the pairs are correctly matched.
(c) Option (c) contains the incorrect pair. It can be
corrected as
In Drosophila, XX-XY type of sex-determination is
seen, i.e. same as humans.
Rest of the pairs are correct.
(a) In XX-XY type of sex-determination, male are
heterogametic, i.e. produces two types of sperms with X
and Y. But females are homogametic, i.e. produces only
single type of ovum with X.
(c) Sex-determination in honeybee is called
haplo-diploid sex-determination system.
Parents
Gametes
F1 - generation
Female
32
Male
16
Meiosis
Mitosis
16
16
Male
16
16
Female
32
102 (a) The sex-determination in honeybee is based on the
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Answers & Explanations
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107
108
number of sets of chromosomes an individual receives.
An offspring formed from the union of a sperm and an
egg develops as a female (queen or worker) and an
unfertilised egg develops as a male (drone) by means of
parthenogenesis.
(a) Mutation is the phenomenon which results in
alteration of DNA sequences and consequently results
in change in the phenotype and genotype of an
organism. The term ‘mutation’ was introduced by Hugo
de Vries in 1901 in his mutation theory of evolution.
(d) In most cases if there is a change in genotype than it
ultimately leads to change in phenotype too. Mutation
may also involve change in the rate of metabolism in
some individuals.
(b) Point mutations refer to those mutations which arise
due to change in a single base pair of DNA. This change
may either be deletion or addition of one or more bases
or it may be due to substitution of one base by another.
(d) Transition occurs when a purine base (A or G) is
replaced by another purine base. Transversion occurs
when a purine base is substituted by a pyrimidine base
or vice-versa.
Thus, the number of possible transitions and
transversions among the four bases (A, T, G, C) are 4
and 8, respectivley and can be represented by the figure
given below
T
3
1
2
1
2
4
4
G
A
3
8
6
7
5
C
(Transition → and Transversion
)
110 (c) Deletion and insertion of one base leads to a change
in the entire DNA base pair sequence, which leads to
frame shift mutation. Since the deletion or insertion in
DNA base pair sequence is occurring in the reading
frame. This is named as frame shift mutation.
111 (c) Mutagens may be physical agents such as X-rays,
α-rays, etc., which cause mutation and chemical agents
such as mustard gas, etc., which cause changes in the
DNA sequence in an organism.
112 (d) The study of inheritance of genetic traits in several
generations of a family of human beings is done in the
form of a family tree diagram called the pedigree chart
and the method is called pedigree analysis.
116 (d) Cytoplasmic or Mitochondrial inheritance is the
inheritance in which a trait is passed only from the
mother to offspring. The genes involved in this mode of
inheritance are present in the cytoplasm of ova.
Since, after fertilisation, cytoplasm is contributed to the
zygote by ova, the genes for a specific trait are passed
on from the mother to the offspring.
117 (a) In the given pedigree chart only males are affected.
So, it can be easily inferred that the given trait is
connected to Y-chromosome.
118 (b) The type of pedigree given is autosomal recessive.
It can be explained by the detailed pedigree chart given
below
Let ‘a’ be the recessive autosomal allele.
Aa
aa
Aa
aa
aa
Aa or Aa
AA
or Aa AA
or
Aa
Aa
AA
or
Aa
aa
Aa
aa
Aa
AA
or Aa
Aa
aa AA or Aa
119 (a) Figure (a) is correct as the case is that of criss-cross
inheritance. It is a type of sex-linked inheritance, where
a parent passes the traits to the grand child of the same
sex through offspring of the opposite sex. The father
passes the traits to grandson through his daughter
(diagynic), while the mother transfers traits to her grand
daughter through her son (dia-andric).
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CHAPTER 05 > Principles of Inheritance and Variation
120 (c) For the pedigree chart given in the question, the
cause of the trait can either be due to a dominant allele
or a recessive allele.
It can be depicted by the two cases given below
I. When ‘A’ is the dominant allele for the trait and ‘a’ is
the normal recessive allele.
aa
Aa
aa
Parents
XY
×
XcX
(Normal man) (Carrier woman)
AA
aa
Aa
aa
Aa
Aa
aa
Aa
aa
aa
II. When ‘a’ is the recessive allele for the trait and ‘A’ is
the normal dominant allele.
AA
AA
or Aa
aa
aa
aa
AA
or Aa
aa
AA
or Aa
aa
aa
Aa
Aa
Aa
121 (d) The genotype of the individual marked ‘M’ has to
be X h X, i.e. she has to be the carrier, so as to produce
an individual who is affected, in the last generation.
122 (a) Inheritance of ear lobes is determined by an
autosomal gene with two alleles. The allele ‘F’ for free
ear lobe is dominant over allele ‘f ’ for attached ear
lobe. Thus, the type of pedigree chart can only the
obtained when the parents are heterozygous. It can be
explained by the chart given below
Ff
Hence, out of the 4 offspring possible 25% of sons are
diseased and 25% are normal. Similarly, 50% daughters
normal out of which half are carriers.
125 (b) Colour blindness is an X-linked disease. So, a
woman whose father is colourblind will be a carrier for
the disease.
Ff
X
Xc
Y
X
Gametes
XY F1-generation
XX
XXc
XcY
(Carrier (Normal (Colourblind (Normal
son)
daughter) daughter) son)
So, the possibility of a colourblind daughter (i.e. X cX c)
in F1 -generation is 0%.
126 (a) Colour blindness is a sex-linked recessive genetic
disorder involving the X-chromosome. Thus, according
to the situation given in the question, a man whose
father was colourblind will be, normal, i.e. XY and a
woman whose mother was colourblind and father was
normal is a carrier, i.e. XX c.
Thus, when marriage happens between two such
individuals percentage of a male child to be colourblind
is 25% (this can be easily observed from the cross given
below)
Carrier
mother
X
XX
Normal
father
Xc
×
X
Y
c
Xc X
XY
X Y
(Normal (Normal (Carrier (Colourblind
daughter) son) daughter)
son)
Ff
ff
Ff
Ff
condition and she can transmit the carrier allele to both
her son and daughter. The resulting son will affected
because X-linked disorder always affect males as males
contain a single X-chromosome. The daughter offspring
will be a carrier, but not diseased because females are
affected by X-linked disorder in homozygous recessive
condition only, i.e. two recessive alleles are required.
Parents
Gametes
XhX
XY
(Carrier mother) X (Normal father)
Xh
XhX
F1 -generation Carrier
X
XhY
X-linked
daughter diseased
son
X
XX
127 (a) A colourblind father (genotype X cY) would produce
carrier daughters (genotype XX c). When a carrier
female ( XX c ) marriages a normal man (XY), the types
of offspring produced would be all normal daughters
and half of the sons (50%) would be colourblind and the
remaining half would be normal. This pattern of
inheritance can be explained by the following cross
(Carrier mother) XXc
Gametes X
×
X
XY
X
c
X
c
XX
X
Y
Normal Normal
daughter
son
XY (Normal father)
c
X
X X
Y
X Y
c
Y
XY
128 (a) Haemophilia is an X-linked recessive gene disorder.
It is a blood clotting disorder and shows criss-cross
inheritance. In this, characters from father are
transmitted to daughter and from mother to son.
Answers & Explanations
ff
124 (d) In the given problem, the woman has an X-linked
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129 (c) Haemophilia is a sex-linked recessive disease, which
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Answers & Explanations
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shows its transmission from unaffected carrier female to
some of the male progeny has been widely studied. In
this disease, a single protein that is a part of the cascade
of proteins involved in the clotting of blood is affected.
Due to this, in an affected individual, a simple cut will
result in non-stop bleeding.
(d) During phenylketonuria the affected individual lacks
an enzyme that converts amino acid, phenylalanine into
tyrosine (i.e. phenylalanine hydroxylase is absent). As a
result of this phenylalanine is accumulated and
converted into phenylpyruvic acid and other derivatives.
This lack of the enzyme is due to the presence of
autosomal defective gene on chromosome number 12.
(d) Thalassemia is also an autosome linked recessive
blood disease transmitted from parents to the offspring
when both the partners are unaffected carrier for the
gene (or heterozygous). The defect could be due to
either mutation or deletion which ultimately results in
reduced rate of synthesis of one of the globin chains
(α and β-chains) that make up haemoglobin. This causes
the formation of abnormal haemoglobin molecules
resulting into anaemia which is characteristic of the
disease.
(a) Aneuploidy occurs when the chromatids fail to
segregate during cell division, resulting in gain or loss
of a chromosome.
(a) Polyploid cells have a chromosome number that is
more than double the haploid number, e.g. Triticum
aestivum (wheat) is a hexaploid ( 6n ).
(a) Non-disjunction in meiosis results in trisomy, i.e.
the presence of an extra chromosome. Such individuals
have 47 chromosomes instead of 46. Some examples of
such abnormalities include Down’s syndrome
(21-trisomy), Patau’s syndrome (13-trisomy) and
Edward’s syndrome (18-trisomy).
(a) Down’s syndrome is an abnormality caused by an
autosomal primary non-disjunction. Non-disjunction is
the failure of chromosomes to disjoin or separate and
move away to opposite poles. Non-disjunction of 21st
chromosome during oogenesis is the cause of Down’s
syndrome. It occurs due to the presence of an additional
copy of chromosome number 21 (trisomy of 21st
chromosome) in humans.
(c) Karyotype of people suffering from Down’s
syndrome have 47 chromosomes ( 45 + XY in males,
45 + XX in females) instead of 46. It is caused due to
the presence of an extra chromosome, i.e. chromosome
number 21. Thus, it is also known as 21 trisomy.
(a) In Klinefelter’s syndrome, the affected individual
has overall masculine development, gynaecomastia and
is sterile. This condition is represented by the karyotype
44 + X (47) due to the presence of an extra
X-chromosome in males.
(d) Both options (a) and (c) are correct. This can be
explained as
In klinefelter’s syndrome, the sex chromosomes
genotype is XXY, i.e. there is one extra X-chromosome.
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150
151
152
153
154
155
156
157
This extra X can come in two conditions, when there is
non-disjunction in egg, i.e. XX egg and Y sperm and
where is non-disjunction in sperm, i.e. X egg and XY
sperm.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
Offspring bear characteristics of both the parents. These
characters pass from the parents via their gametes into
their progeny. This is called inheritance.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
True breeding lines show inheritance of pure characters
for several generations. This is because true breeding
lines are homozygous for the traits. Therefore, Mendel
conducted cross-pollination experiments, between
different true breeding lines to study the concept of
inheritance.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
There was no blending of characters in the progeny of
F2 -generation. As a result, the offspring exhibited traits
which were exactly identical to their parents.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Genes are passed on from one generation to the next,
and thus called as the units of inheritance.
(c) Assertion is true, but Reason is false and it can be
corrected as
Meiosis occurs during the process of gamete formation
which leads to the formation of haploid gametes.
(a) Both Assertion and Reason are true, but Reason is
the correct explanation of Assertion.
In codominance, the progeny of F1 -generation resembles
both the parents due to the equal expression of the two
alleles involved.
An example of the phenomenon of codominance is
ABO blood grouping in humans. In this antigen A,
product of the alleles I A and antigen B, product of the
alleles I B are codominant in individual with AB blood
group.
(b) Both Assertion and Reason are correct, but Reason
is not the correct explanation of Assertion.
Behaviour of chromosomes is considered to be parallel
to that of the genes. This is because, as genes are passed
on from one generation to the next, chromosomes also
get passed on from one generation to the next.
(c) Assertion is true, but Reason is false and it can be
corrected as
Genes, which tend to get passed on together from one
generation to the next, are located very close to each
other on a chromosome. Such genes are called as linked
genes.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Insects show male heterogamety as females have XX
sex chromosomes and males have XO sex
chromosomes.
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CHAPTER 05 > Principles of Inheritance and Variation
159
160
161
162
163
164
165
166
corrected as
Male honeybees, i.e. drones are haploid whereas female
honeybees, i.e. queen and workers are diploid.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
The non-allelic genes for red hair and prickles are
inherited together as these are located in close
association on the same chromosome.
(c) Assertion is true, but Reason is false and it can be
corrected as
In Klinefelter’s syndrome males are sterile as individual
possess 47 chromosomes (44 + XXY ).
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Phenylketonuria is an autosomal herditary disease,
which occurs due to an autosomal defective gene on
chromosome number 12. The defective gene causes
body’s failure to oxidise amino acid, phenylalanine to
tyrosine because of defective enzyme, phenylalanine
hydroxylase. Thus, the patient shows the presence of
phenylalanine acid in urine.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation for Assertion.
Sickle-cell anaemia is an autosomal linked recessive
disorder. The gene for this disorder is present on an
autosome and an individual is said to be affected only
when both the genes or a pair of allele (mutated or
affected) are inherited from the carrier or affected
parents.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Down’s syndrome is a chromosomal disorder. It is
caused due to the presence of an additional copy
chromosome 21 (trisomy 21).
(b) The statement in option (b) is not true. It can be
corrected as
The tightly linked genes on chromosomes show 100%
parental types and 0% recombinants. Two genes that
undergo independent assortment indicated by a
recombinant frequency of 50% are on non-homologous
chromosomes indicated for apart in a single
chromosome. As the distance between two genes
increases, crossing over frequency increases. This
results in the formation of more recombinant gametes
and fewer parental gametes.
Rest of the statements are true.
(c) The statement is option (c) is incorrect and can be
corrected as
The law of segregation applies universally. The
reappearence of parental (red and white) flowers in the
F 2 -generation also confirms, that law of segregation
applies in this experiment.
Rest of the statements are correct.
(b) The statement in option (b) is incorrect and can be
corrected as
In domesticated fowls, sex of progeny depends on the
type of egg rather than type of sperm.
Rest of the statements are correct.
167 (b) The statement in option (b) correctly describes the
manner of determining the sex.
Rest of the statements are incorrect and can be
corrected as
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Heterozygous sex chromosomes (ZW) determine
female sex in birds.
XO condition in humans as found in Turner’s
syndrome determines male sex.
Heterozygous sex-chromosomes (XY) produces males
in Drosophila.
168 (d) The statement in option (d) is incorrect and can be
corrected as
Female homogamety is found in mammals.
Rest of the statements are correct.
170 (a) The statement in option (a) is incorrect and can be
corrected as
Humans contain 22 pairs of autosomes (XX) and one
pair of sex chromosome (XY).
Rest of the statements are correct.
171 (a) The statement in option (a) is incorrect for
haemophilia and can be corrected as
It is a sex-linked recessive disease.
Rest of the statements are correct.
172 (c) The statement in option (c) is correct. Rest of the
statements are incorrect and can be corrected as
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Sickle-cell anaemia is the qualitative defect of
synthesising an incorrectly function globin.
Thalassemia is the quantitative defect of synthesising to
few globin molecules.
173 (c) The statement in option (c) is incorrect and can be
corrected as
In thalassemia, the α and β-globin chains of
haemoglobin are not absent rather their production is
affected.
Rest of the statements are correct.
174 (d) The statement in option (d) is correct with respect
to monohybrid cross and dihybrid cross.
Rest of the statements are incorrect and can be corrected as
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Both monohybrid and dihybrid crosses can be
performed for one or more generations.
Both monohybrid cross and dihybrid cross involves
two parents.
Both monohybrid cross and dihybrid cross can produce
two or more progeny.
175 (a) The statement in option (a) is correct with respect to
the law of segregation.
Rest of the statements are incorrect and can be
corrected as
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The paired factors or alleles segregate from each other
such that a gamete recieves only one of the factor
present in the origin at paired form.
Answers & Explanations
158 (c) Assertion is true, but Reason is false and it can be
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Homozygous parent produces similar types of gametes
whereas heterozygous ones produce two types of
gametes each with one allele to equal proportion.
184 (d) Statements I, II and III all are incorrect and can be
corrected as
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177 (b) The statement in option (b) is incorrect and can be
corrected as
The vast majority of mutations produce recessive
alleles.
178 (c) Statements I and IV are correct. Statements II and III
are incorrect and can be corrected as
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Characters blend in both homozygous and
heterozygous conditions.
Not all characters (only some) show dominance in
humans.
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185 (a) Statements I and II are the correct reasons for why
Mendel could not find out about linkage. Statements III
and IV are incorrect and can be corrected as
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179 (a) Statement I is the only correct statement about
linkage.
Rest of the statements are incorrect and can be
corrected as
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Less parental combinations are produced in
F2-generation.
Genotype which were present in F1 hybrid, reappeared
in low frequency in F2-generation.
Linkage is the phenomenon in which two genes are
physically linked.
180 (b) Statement I is correct. Statements II, III and IV are
incorrect and can be corrected as
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A recessive allele is not weaker than the dominant
allele.
A recessive allele does not show its effect because of
modified or different enzymes. A recessive allele can
express in few cases, e.g. incomplete dominance.
It is not necessary that dominant allele is always better.
Lightly linked genes on the same chromosome show
low recombination.
Genes far apart on the same chromosome show high or
more recombination.
Genes loosely linked on the same chromosome show
higher recombination than tightly linked genes.
The genes for all the traits were present on different
chromosomes or were located for apart on the same
chromosomes.
190 (d) Both statements I and II are false and can be
corrected as
In male and female insects, the number of chromosomes
are not same.
The females are homozygous, containing XX
chromosomes, while males contain only one
X-chromosome and represented as XO.
207 (b) All the genes, present on a particular chromosome
form a linkage group. The number of linkage group of a
species corresponds to the total number of different
chromosomes of that species.
208 (b) If a cross between two tall plants resulted in a few
dwarf offspring, then the parental genotypes are Tt
and Tt.
It can be explained by the following example
The F1 plants of genotype, Tt are self-pollinated [both
tall (T), but with dwarf (t) alleles].
181 (b) Statement I is incorrect and can be corrected as
Mutations are not acquired as they occur by chance and
are selected by nature.
Rest of the statements are correct.
182 (b) Statements I and II are correct. Statements III and
IV are incorrect and can be corrected as
Answers & Explanations
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Codominance cannot be manifested phenotypically in
humans as ABO blood group in humans is three alleles
of gene I (IA ,IB ,i).
ABO blood grouping system in humans does not
follow Mendel’s laws of inheritance.
183 (d) Statements I and II are correct. Statements III and
IV are incorrect and can be corrected as
l
l
Dihybrid test cross ratio is 1 : 1 : 1 : 1 in F2-generation,
i.e. show 4 phenotypes and genotypes in equal
proportions.
Linked genes do not separate frequently.These genes
remain together because linked gene lie very closely to
each other.
t
T
TT
×
Tt
t
T
Tt
Selfing
tt F1-generation
Phenotypic ratio : Tall : Dwarf
3 : 1
Genotypic ratio : Pure tall : Hybrid : Pure dwarf
:
2 :
1
1
209 (d) If a 9 : 3 : 3 : 1 ratio is obtained in a dihybrid cross,
it denotes that alleles of two genes are segregate
independently.
It can be explained as follows
If a pea plant with round and yellow seeds is crossed
with a plant with wrinkled and green ones all F1 hybrids
possess yellow and round seeds. Since, yellow colour is
dominant over the green and the round shape is
dominant over the wrinkled.
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CHAPTER 05 > Principles of Inheritance and Variation
When IA and IB are present together, both express
equally and produce the surface antigens A and B.
Thus, a person having genotype IA IB would show the
blood group as AB.
216 (c) When both mother and father are heterozygous for
‘A’ and ‘B’ blood group, respectively. Then few of their
progeny would be with ‘O’ blood group. This can be
explained as
210 (d) Mendel’s dihybrid cross is depicted below
(Wrinkled green) Parental
rryy
generation
Gametes
ry
RY
(Round-yellow) RrYy
F1 -generation
Selfing
Parents
Phenotypic Round : Round : Wrinkled :
yellow
green
yellow
ratio
9
:
3
:
3
:
Genotypic
1:2 : 2 : 4 : 1 : 2 : 1
ratio
Wrinkled
green
1
: 2 :
Gametes
211 (d) The ratio of offspring will be 1 : 1 for the cross
mentioned in the question. This can be explained as
×
aabb
(Homozygous
recessive)
AB ab
ab
Only these two gametes
will be formed because
'A' and 'B' are linked genes
ab
AB
AaBb
1
ab
aabb
1
Thus, both genotypic and phenotypic ratio will be 1 : 1.
215 (b) ABO blood grouping in humans is an example of
codominance.
IB
Mother
(A group)
I Ai
IA
i
i
1
Thus, from the cross, it can be determined that the
number of phenotypes and genotypes in the
F2 -generation of a Mendelian dihybrid cross is 4 and 9,
respectively.
AaBb
(Heterozygous)
Father
(B group)
I Bi
F1 -generation
I AI B
AB blood
group
I Bi
B blood
group
I Ai
A blood
group
ii
O blood
group
217 (a) The distance between the genes and percentage of
recombination shows a direct relationship. This can be
explained as when genes are close together, or are
linked exhibit low recombination frequencies. And
when they are far apart the recombination is high.
219 (a) The 17 and 18 chromosomes bearing organisms are
males and females, respectively. In large number of
insects like cockroach and grasshopper, XX-XO type of
sex-determination is seen, which shows male
heterogamety. Here XX represent females and XO
(which is basically single X chromosome) represents
males. Therefore consequently the number of
chromosomes in them would be 17 in males and 18 in
females.
223 (a) Aneuploidy involves changes in the chromosome
number either by additions or deletions of less than a
whole set. In this case organism gains or loses one or
more chromosomes but not a complete set. Thus, the
karyotypic conditions of 2n ± 1 or 2n ± 2 denote
aneuploidy.
Answers & Explanations
(Round yellow)
RRYY
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CHAPTER > 06
Molecular Basis
of Inheritance
NEET
Å
Å
KEY NOTES
Mendel suggested that there are some factors or genes
which help to maintain the phenotypes and genotypes of
organisms for generation after generation.
It was later established that DNA (Deoxyribonucleic Acid)
is the genetic material in majority of organisms, while RNA
acts as the genetic material in some viruses, but has
additional roles as well. RNA functions as adapter,
structural and in some cases as catalytic molecule.
DNA (Deoxyribonucleic Acid)
Å
Å
It is a long polymer of deoxyribonucleotides. The length of
DNA is usually defined as number of nucleotides (or a pair
of nucleotide referred to as base pairs) present in it.
For example, a bacteriophage known as φ × 174 has 5386
nucleotides, bacteriophage lambda has 48502 bp,
Escherichia coli has 4.6 × 206 bp and haploid content of
human DNA is 3. 3 × 109 bp.
Structure of a Polynucleotide Chain
A nucleotide is composed of a nitrogenous base, pentose sugar
and a phosphate group.
1. A nitrogenous base It is the nitrogen containing organic
molecule having similar physical properties of a base.
Å There are two types of nitrogenous bases
Purines Adenine and Guanine.
Pyrimidines Cytosine, Uracil and Thymine.
Å Thymine is present in DNA, while uracil is present in
RNA in place of thymine (5-methyl uracil, another name
for thymine).
n
n
2. A pentose sugar Two types of sugars are present
Å
Discoveries Related to Structure of
DNA
Å
Friedrich Miescher in 1869, first identified DNA as an
acidic substance present in the nucleus and named it as
‘nuclein’.
Å
James Watson and Francis Crick, proposed a very simple
double helix model for the structure of DNA in 1953 based
on X-ray diffraction data.
Å
Erwin Chargaff proposed that for a double-stranded DNA,
the ratio between adenine and thymine and guanine and
cytosine are constant and equals one.
A+G
A + G = T + C or
=1
T+C
Ribose (in case of RNA)
Deoxyribose (in case of DNA)
3. A phosphate group It is in the form of H3 PO4 .
Å
Å
Nucleoside and nucleotide A nucleoside is formed when
a nitrogenous base is linked to a pentose sugar through
N-glycosidic linkage.
Å
Nucleotides are the phosphoric esters of nucleosides.
n
n
Nucleotides are joined by 3′−5′ phosphodiester bonds
to form a dinucleotide.
Alternate deoxyribose and phosphate residues joins to
form the polynucleotide chain.
Double Helix Structure of DNA
Å
Å
DNA is made up of two polynucleotide chains, where the
backbone is constituted by sugar, phosphate and the bases
project inside.
The two chains have anti-parallel polarity, i.e. 5′→ 3′ for one,
3′→ 5′ for another.
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CHAPTER 06 > Molecular Basis of Inheritance
Å
Å
Å
The bases in two strands are paired through hydrogen bond
(H—bonds) forming base pairs (bp). Adenine forms two
hydrogen bonds with thymine and vice-versa. Guanine bonds
with cytosine by three H—bonds and vice-versa. Thus, a
purine always comes opposite to a pyrimidine forming a
uniform distance between the two strands.
The two chains are coiled in a right-handed fashion. The
pitch of the helix is 3.4 nm and there are roughly 10 bp in
each turn. Due to this, the distance between a base pair in a
helix is about 0.34 nm.
The plane of one base pair stacks over the other in double
helix. This confers stability to the helical structure in addition
to H—bonds.
The Search for Genetic
Material
The experiments given below established that DNA is the
genetic material in majority of organisms.
Transforming Principle
Å
Å
Central Dogma
Å
Injection
S-strain → Mice → Mice died
In 1957, Francis Crick proposed the central dogma in
molecular biology. According to this, the genetic information
flows from DNA → RNA → Protein.
DNA
replication
DNA
Transcription
Translation
mRNA
Injection
R-strain → Mice →
S-strain → Mice → Mice live
(Heat-killed)
Injection
Protein
S-strain → Mice → Mice die
(Heat-killed)
+
R-strain (Live)
The flow of information can be in reverse direction also, i.e.
from RNA to DNA in some viruses, such as TMV.
Å
Packaging of DNA Helix
Å
Å
Å
Å
Å
Å
Mice lived
Injection
Central dogma
Å
Frederick Griffith (1928) carried out a series of
experiments with Streptococcus pneumoniae (bacterium
causing pneumonia).
He used two strains of this bacterium, i.e. one forming
smooth colonies with capsule (S-type) and the other
forming rough colonies without capsule (R-type) and
gave the following observations
In prokaryotes, such as E. coli, the DNA is not scattered
throughout the cell even though they do not have a defined
nucleus. DNA (being negatively charged) is held with some
proteins (that are positively charged) in a region termed as
nucleoid. The DNA in nucleoid is organised in large loops
held by proteins.
In eukaryotic cells, there is a set of positively charged
proteins called histones. Histones are rich in basic amino
acid residuces lysine and arginine. These are organised to
form a unit of eight molecules called histone octamer.
The negatively charged DNA is wrapped around the
positively charged histone octamer to form a structure called
nucleosome. A typical nucleosome contains 200 bp of DNA
helix.
Nucleosome constitutes the repeating unit of a structure in
the nucleus called chromatin, thread-like stained (coloured)
bodies seen in nucleus.
The ‘beads-on-string’ structure of nucleosome in chromatin
are packaged to form chromatin fibres which further coil and
condense at metaphase stage of cell division to form the
chromosomes. The packaging of chromatin at higher level
requires additional set of proteins that collectively are
referred to as Non-Histone Chromosomal (NHC) proteins.
Some regions of chromatin which are loosely packed (stain
light) are called euchromatin (active chromatin). In some
regions, chromatin is densely packed (stain dark), it is called
heterochromatin (inactive chromatin).
He concluded that the R-strain bacteria had somehow
been transformed by the heat-killed S-strain bacteria,
which must be due to the transfer of the genetic material
(transforming principle).
Biochemical Characterisation of
Transforming Principle
Å
Å
Å
Å
Å
Oswald Avery, Colin MacLeod and Maclyn McCarty
(1933-44) worked to determine the biochemical nature of
‘transforming principle’ in Griffith’s experiment in an in
vitro system.
From the heat-killed S-cells, they purified biochemicals
(proteins, DNA, RNA, etc.) to observe, which
biochemical could transform live R-cells into S-cells.
They discovered that DNA alone from heat-killed S-type
bacteria caused the transformation of non-virulent
R-type bacteria into virulent S-type bacteria.
Protein-digesting enzymes (proteases) and RNA
digesting enzymes (RNases) did not cause this
transformation. This proved that the ‘transforming
substance’ was neither protein nor RNA.
DNA-digesting enzyme (DNase) caused inhibition of
transformation, which suggested that DNA caused the
transformation. Thus, it was concluded that DNA is the
hereditary material.
The Genetic Material is DNA
Å
Å
Alfred Hershey and Martha Chase gave another
definitive evidence for DNA as genetic material in 1952.
In their work, they described that the phage DNA enters
the host cell and works as a genetic material.
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Å
Outline of their experiment is given below
[Viral DNA labelled]
32
DNA labelled with P
[Viral coat labelled]
Protein coat labelled with 35S
Viruses have infected bacteria
Viruses have infected bacteria
Blender separates viral coats
from bacteria
Blender separates viral coats
from bacteria
Viral replication occurs
Viral replication occurs
Å
Therefore, DNA has evolved from RNA with chemical
modifications which make it more stable.
Å
There are following three types of RNA, i.e. messenger
RNA ( mRNA), which provides the template for
transcription, transfer RNA (tRNA) which brings
amino acids and reads the genetic code and ribosomal
RNA ( rRNA), which plays structural and catalytic role
during translation.
DNA Replication
Å
Radioactivity within bacterial DNA
Radioactivity within viral coats
Radioactive DNA enters
Radioactive protein did not enter
from phage to bacteria indicating from virus to bacteria indicating that
that DNA acts as genetic material protein does not act as genetic material
(a)
(b)
The Hershey and Chase experiment
Properties of Genetic Material
(DNA v/s RNA)
Å
Å
Genetic material is the substance which controls the
inheritance of traits from one generation to next.
Following are the criteria that a molecule must fulfil to act as
a genetic material
It should be able to replicate itself.
It should be stable both chemically and structurally.
It should provide the scope for slow changes (mutation),
which are required for evolution.
It should be able to express itself in the form of ‘Mendelian
characters’.
Scheme for replication of DNA termed as
semiconservative DNA replication was proposed by
Watson and Crick (1953). According to this, the two
strands would separate and act as a template for the
synthesis of new complementary strands. Thus, each
DNA molecule formed would have one parental and
one newly synthesised strand.
The Experimental Proof
Matthew Meselson and Franklin Stahl (in 1958)
conducted the following experiment with Escherichia coli
to prove that DNA replicates semiconservatively.
Å
They grew many generations of E. coli in a medium that
contained 15 NH4Cl ( 15 N is the heavy isotope of
nitrogen) as the only source of nitrogen.
n
n
Å
n
n
Å
DNA from such bacterium had an intermediate density
(hybrid), one generation after the transfer from 15 N to
14
N. After another generation, it was composed of equal
amount of hybrid DNA and light DNA.
Å
Similar experiments on ‘Vicia faba’ (faba beans) were
conducted by Taylor and colleagues in 1958, involving
the use of radioactive thymidine. The results were that
the DNA in chromosomes also replicate
semiconservatively.
Differences between DNA and RNA
DNA
RNA
It is double-stranded with exception
of some viruses.
It is generally single-stranded.
It is the genetic material in all living
organisms.
It is the genetic material in some
viruses only.
The sugar is deoxyribose.
The sugar is ribose.
Nitrogenous bases present are adenine, Nitrogenous bases present are
guanine, thymine and cytosine.
adenine, guanine, cytosine and uracil.
It is chemically less reactive and
structurally more stable.
It is chemically more reactive and
structurally less stable.
It usually occurs inside the nucleus
and in some cell organelles.
Small amount of RNA occurs inside
the nucleus. Most of it is found in
the cytoplasm.
The Machinery and the Enzymes
The process of replication requires a set of catalysts
(enzymes) which are given below
Å
DNA-dependent DNA polymerase It is the main
enzyme which uses a DNA template to catalyse the
polymerisation of deoxynucleotides.
These enzymes are highly efficient and also help in
removing mismatched nucleotides by a mechanism
called proof reading.
Å
Helicase This enzyme unwinds the DNA strand, i.e.
separates the two strands from one point, for the
formation of a replication fork.
RNA World
Å
Å
Ribonucleic Acid (RNA) is said to be the first genetic material.
It is evident through various scientific researches that
essential life processes such as metabolism, translation and
splicing, etc., evolved around, RNA. RNA used to act as
genetic material as well as a catalyst. But RNA being a
catalyst was reactive and hence unstable.
NEET
They observed that 15 N was incorporated into the
newly synthesised strand of DNA. This heavy DNA
could be distinguished from the normal DNA by
centrifugation in a cesium chloride (CsCl) density
gradient.
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CHAPTER 06 > Molecular Basis of Inheritance
Å
Å
Topoisomerase The unwinding of DNA creates a tension in
the DNA strands, which gets released by the enzyme
topoisomerase.
DNA ligase It facilitates the joining of DNA strands
together by catalysing the formation of phosphodiester
bond. It also repairs single strand breaks in duplex DNA.
Process of DNA Replication
Å
Å
Å
Å
Å
Replication is an energy expensive process,
deoxyribonucleoside Triphosphates (dNTPs) serve the dual
purpose of acting as a substrate and providing energy (from
two terminal phosphates).
Transcription Unit and The Gene
Å
Gene is the functional unit of inheritance. The DNA
sequence coding for tRNA or rRNA molecule also
defines a gene.
Å
Cistron is the segment of DNA which codes for a
polypeptide.
Å
In a transcription unit, the structural gene could be
Å
In a long DNA molecule, replication takes place within a
small opening of the DNA helix, known as replication fork.
Replication begins at a definite region in a E. coli, DNA
molecule known as origin of replication (ori), which has
recognition site for DNA polymerase and also provides site
for attachment of RNA primer.
Monocistronic (mostly in eukaryotes).
Polycistronic (mostly in bacteria or prokaryotes).
The monocistronic structural genes in eukaryotes have
interrupted coding sequences. They are of two types
n
DNA-dependent DNA polymerases catalyse polymerisation
only in one direction, i.e. 5′→3′.
Due to this, on one strand called the leading strand with
polarity 3′→5′, replication is continuous. While on the other
strand called the lagging strand with polarity 5′ → 3′
replication is discontinuous, i.e. in small fragments called
Okazaki fragments. The fragments synthesised are joined by
DNA ligase.
n
n
n
Å
Exons are the coding sequences or expressed
sequences that appear in mature or processed RNA.
Introns are the intervening sequences which do not
appear in mature or processed RNA. These only
interrupt exons. The split gene, i.e. gene with both
exons and introns is a characteristic of eukaryotic
DNA.
The promoter and regulatory sequences of a structural
gene also affect the inheritance of a character. Hence, the
regulatory sequences are sometimes loosely defined as
regulatory genes.
Transcription in Prokaryotes
Å
Transcription
It is the process of copying genetic information from one strand
of the DNA into RNA. This process is governed by the
principle of complementarity, except adenosine now forms
base pair with uracil instead of thymine.
DNA-dependent RNA polymerase is the single enzyme
that catalyses transcription of all types of bacterial RNA,
and takes place in the following three steps
Initiation RNA polymerase binds to promoter and
initiates transcription by associating transiently with
initiation factor (σ).
Elongation Chain elongation proceeds in the 5′→ 3′
direction and the transcription bubble travels with
RNA polymerase. The RNA polymerase after
initiation of transcription loses the σ factor, but
continues the polymerisation of ribonucleotides to
form RNA.
Termination When RNA polymerase reaches the
terminator region of DNA, which is GC rich and has
a hairpin-like structure, the nascent RNA separates
and the RNA polymerase falls off resulting in
termination of transcription.
n
n
Transcription Unit
Å
A transcription unit of DNA is defined primarily by three
regions in the DNA
A promoter
The structural gene
A terminator
n
n
n
n
Å
Å
The enzyme DNA-dependent RNA polymerase catalyses
the polymerisation in only one direction (i.e. 5′→ 3′
direction).
The strand with 3′ → 5′ polarity is known as the template
strand. The strand with 5′ → 3′ polarity and same sequence
as RNA (except thymine at the place of uracil) displaced
during transcription, is known as coding strand.
Å
A promoter is a DNA sequence that provides binding site for
RNA polymerase. It is located at 5′ end (upstream) of the
structural gene and its presence defines the template and
coding strands.
Å
The structural gene in a transcription unit is flanked by the
promoter and terminator.
Å
A terminator is located towards the 3′ end (downstream) of
the coding strand. It usually defines the end of transcription.
Transcription in Eukaryotes
The process of transcription in eukaryotes is similar to that
in prokaryotes. Structural genes are monocistronic in
eukaryotes. Two additional complexities are present in
eukaryotes as given below
Å
The first complexity is that there are atleast three RNA
polymerases in nucleus in addition to RNA polymerase
found in organelles and these are
n
RNA polymerase-I transcribes rRNAs
(28S, 18S, 5.8S).
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RNA polymerase-II transcribes precursor of mRNA,
which is called heterogeneous nuclear RNA (hnRNA).
RNA polymerase-III transcribes tRNA,
5srRNA (small ribosomal RNA) and snRNAs
(small nuclear RNAs).
The second complexity is that the primary transcript contains
both exons and introns. Thus, the process of splicing is
performed to remove the introns and join the exons in a
proper order to allow translation.
The RNA formed is called hnRNA, which undergoes
additional processing as follows
Capping In capping, methyl guanosine triphosphate, an
unusual nucleotide is added to the 5′ end of hnRNA.
Tailing In tailing, adenylate residues are added at 3′ end
in a template independent manner.
n
Å
n
Å
Å
The tRNA has a secondary structure like clover leaf.
But its three dimensional structure depicts it as an
inverted L-shaped molecule. tRNA has five arms or
loops, as follows
n
n
n
n
n
Anticodon loop has bases complementary to the
code. tRNAs are specific for specific amino acid.
Amino acid acceptor end where amino acids bind.
T-loop helps in binding to ribosome.
D-loop helps in binding aminoacyl synthetase.
Variable loop is variable in both nucleotide
composition and in length.
n
Translation
n
Å
The fully processed hnRNA, now called mRNA, gets
transported out of the nucleus for translation.
Genetic Code
Å
Å
It is the relationship between the sequence of nucleotides on
mRNA and the sequence of amino acids in the polypeptide.
Important features of genetic code include
The codon is triplet. 61 codons code for all amino acids
and 3 codons do not code for any amino acids, hence, they
function as stop codons.
Some amino acids are coded by more than one codon
hence, the code is degenerate.
Genetic code is unambiguous and specific, i.e. one codon
codes for only one amino acid and is read in a contiguous
fashion without any punctuation marks.
The genetic code is nearly universal, i.e. one codon codes
for the same amino acid in all organisms.
AUG codon has dual function, i.e. it codes for the amino
acid methionine (met) and also acts as an initiation codon.
Three codons function as stop codon or non-sense codons,
which are UAA (ochre), UGA (amber), UAG (opal).
n
The process by which the triplet base sequence (codon)
on mRNA guides the linking of a specific sequence of
amino acids to form a polypeptide on ribosomes is
known as translation.
Translation Machinery
Translation requires a machinery which consists of
ribosome, mRNA, tRNAs, aminoacyl tRNA synthetase
(enzyme that helps in combining amino acid to particular
tRNA) and amino acids.
Å
Initiator tRNA It is a specific tRNA for the process of
initiation and there are no tRNAs for stop codons.
Å
Ribosome It is responsible for protein synthesis.
Ribosome exists as two subunits in its inactive stage
n
n
n
n
n
n
n
tRNA : The Adapter Molecule
Å
The presence of an adapter molecule, which could read the
code and would bind to specific amino acids during
translation was proposed by Francis Crick in 1961.
Å
tRNA was known before genetic code and was called sRNA
(soluble RNA), but later its role as an adapter molecule was
reported.
NEET
Large subunit It consists of two sites, where amino
acids can bind to and be close to each other for the
formation of a peptide bond. Ribosome also acts as
a catalyst (23S rRNA in bacteria is the enzyme,
ribozyme) for peptide bond formation.
Å
Translational unit It is the sequence of RNA flanked
by the start codon (AUG) and the stop codon in
mRNA. It codes for the polypeptide to be produced.
Å
Untranslated Regions (UTRs) These are some
additional sequences in an mRNA which are not
translated. These are present at both the ends, i.e. at
5′ end (before start codon) and at 3′ end (after stop
codon). These improve the efficiency of translation
process.
Mutations and Genetic Code
The sudden inheritable change in the genetic material is defined
as mutation. These include
Å Point mutation is mutation in a single base pair, which is
replaced by another base pair, e.g. in sickle-cell anaemia, a
point mutation in β-globin chain results in the change of
amino acid residue glutamate to valine.
Å Frameshift mutation is a change in the reading frame because
of insertion or deletion of base pairs.
Small subunit When the small subunit encounters
an mRNA, translation of mRNA to protein begins.
Stages of Protein Synthesis
Synthesis of proteins takes place in three stages which are
as follows
1. Initiation In prokaryotes, initiation requires ribosome
(large and small subunits), mRNA, initiation tRNA
and three Initiation Factors (IFs). For initiation to take
place, the ribosome first binds to mRNA at the start
codon (AUG) that is recognised only by the initiator
tRNA.
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Å
Å
Activation of amino acid The formation of peptide bond
requires energy and in first phase, the amino acids are
activated in the presence of ATP and linked to their
cognate tRNA by a process known as charging of tRNA
or aminoacylation of tRNA. In the presence of ATP and
Mg 2+ , amino acids become activated by binding with
aminoacyl tRNA synthetase enzyme.
Å
Å
Francois Jacob and Jacque Monod in 1961 were the first
to propose the concept of a transcriptionally regulated
system, where a polycistronic structural gene is
regulated by a common promoter and regulatory genes.
Å
Such an arrangement is referred as an operon, e.g. lac
(lactose) operon, trp (tryptophan) operon, ara (arabinose)
operon, his (histidine) operon and val (valine) operon,
etc.
Å
Let us take the example of lac operon. Its structure
consists of various genes as follows
Å
One regulatory gene (the i gene), which codes for the
repressor of the lac operon. The term i refers to the word
inhibitor.
Å
Three structural genes are
z gene codes for β-galactosidase (β-gal), that helps in
the hydrolysis of disaccharide into its monomeric
units, i.e. lactose into galactose and glucose.
The amino acids − AMP− enzyme complex is called an
activated amino acid.
2. Elongation of polypeptide chain In this step, another
charged aminoacyl tRNA complex binds to the A-site of
the ribosome.
Å
Lac Operon
A peptide bond forms between carboxyl group
(COOH) of amino acid at P-site and amino group
(  NH3 ) of amino acid at A-site in a reaction catalysed
by the enzyme peptidyl transferase.
n
During this stage, ribosome moves from one codon to
another codon along the mRNA in the 5′ 
→ 3′
direction. Amino acids are then added one-by-one in the
sequence of codons and translated into a polypeptide
sequences, dictated by DNA and represented by mRNA.
3. Termination of polypeptide When the A-site of ribosome
reaches a termination codon, then no tRNA binds to the
A-site of ribosome. At the end, a release factor binds to the
stop codon and which terminates translation and releases
the complete polypeptide from the ribosome.
n
n
Å
Gene expression results in the formation of a polypeptide.
Gene regulation is the mechanism of switching ‘off ’ and
switching ‘on’ of the genes depending upon the requirement
of the cells and the stage of development. The regulation of
gene expression may occur at various levels.
In eukaryotes, it takes place at the following levels
Transcriptional level A primary transcript is formed.
Processing level Regulation of splicing.
Transport of mRNA From nucleus to the cytoplasm.
Translational level
An inducer, i.e. lactose here which is the substrate for
the enzyme β-galactosidase.
Å
If lactose is provided as the carbon source in the growth
medium then in the absence of the preferred carbon
source such as glucose, the lactose is transported into
the cells by the action of enzyme permease. The lactose
then induces the operon.
Å
The i gene synthesises the repressor of the operon.
Repressor binds to the operator region of the operon,
preventing RNA polymerase from transcribing the
operon. However, when inducer such as lactose or
allolactose is present, it binds with the repressor and
inactivates it. Now, that the repressor is inactivated,
RNA polymerase is allowed access to the promoter and
transcription proceeds.
Å
Regulation of lac operon by repressor is referred to as
negative regulation. Lac operon can work under the
control of positive regulation also.
n
n
n
n
Å
In prokaryotes, control of the transcriptional rate of
initiation is the predominant site for control of gene
expression. In a transcription unit, the activity of RNA
polymerase at a given promoter is in turn regulated by the
interaction with accessory proteins, which affect its ability to
recognise start sites.
Å
The accessibility of promoter regions of prokaryotic DNA in
many cases is regulated by the interaction of operators.
Å
The operator region is adjacent to the promoter elements in
most operons and in most cases operator bind a repressor
protein. Each operon has its specific operator and specific
repressor, e.g. lac operator is present only in the lac operon
and it interacts with lac repressor only.
a gene codes for a transacetylase.
Å
Regulation of Gene Expression
Å
y gene codes for permease, that increases the
permeability of the cell to β-galactosides.
Human Genome Project (HGP)
Å
In 1990, a mega project was started to determine the
nucleotide sequence of the entire human nuclear
genome. It was called as Human Genome Project
(HGP).
Å
In addition, HGP was also entrusted to elucidate the
genomes of several other model organisms, e.g. E. coli,
Saccharomyces cerevisiae (yeast), roundworm and mouse.
It was closely associated with the rapid development of
a new area in biology called bioinformatics.
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KEY NOTES
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Master The NCERT > BIOLOGY (Vol-II )
130
Goals of HGP
Important goals of HGP were
Å To identify all the approximately 20,000-25,000 genes in
human DNA.
Å To determine the sequences of the 3 billion chemical base
pairs that constitute human DNA.
Å
Å
Å
Å
To store this information in databases in digital format.
To improve the tools required for data analysis.
To transfer the related technologies to other sectors (like
industries).
To address the Ethical, Legal and Social Issues (ELSI) that
could arise from the project.
Methodologies of HGP
Two major approaches involved were as follows
Å
Repeated sequences are stretches of DNA sequences,
which are repeated many times (some times 100-1000
times). These have no direct coding functions, but help
in understanding chromosome structure, dynamics and
evolution.
Å
Chromosome-1 has the maximum number of genes
(2968) and Chromosome-Y has the least number of
genes (231).
Å
There are about 1.4 million locations in human
genome, where single-base DNA differences occur
(SNPs− Single Nucleotide Polymorphisms). This
information is helpful in finding chromosomal locations
for disease-associated sequences and tracing human
history.
Applications and Future Challenges
Å
Expressed Sequence Tags (ESTs) This method was focused
on identifying all the genes that are expressed as RNA.
Å
Its knowledge is helpful in research involving biological
systems including human biology.
Å
Sequence annotation This method involved sequencing the
whole set of genome (that contained all coding and
non-coding sequence) and then assigning functions to the
different regions in the sequence.
Å
All the genes in a genome, e.g. all the transcripts in a
particular tissue/organ/tumour, can be studied.
Sequencing of Genome
Å
Å
Å
Å
Å
For the process of sequencing, the entire DNA from a cell is
isolated and broken into relatively smaller fragment.
DNA fragments are cloned in a suitable host, (such as
bacteria and yeast) using specialised vectors such as
BAC (Bacterial Artificial Chromosome) and YAC (Yeast
Artificial Chromosome).
Fragments of DNA are then sequenced by automated DNA
sequencers, which work on the principle of a method
developed by Frederick Sanger.
These sequences were arranged accordingly on the basis of
overlapping regions of DNA fragments and were then
aligned using special computer programmes.
DNA Fingerprinting
Å
It also called DNA typing or DNA profiling and is a
technique of determining nucleotide sequences of
certain areas of DNA which are unique to each
individual.
Å
It uses satellite DNA as probe showing high degree of
polymorphism and called it Variable Number of
Tandem Repeats (VNTRs). It was discovered by Alec
Jeffreys in 1985.
Å
The technique has the following steps
DNA isolation DNA is extracted from the cells in a
high speed centrifuge.
Amplification Many copies of the extracted DNA
can be made by the use of Polymerase Chain
Reaction (PCR).
Digestion of DNA by restriction endonucleases.
Separation of DNA fragments by electrophoresis.
Blotting-transfer of the separated DNA fragments to
synthetic membranes like nylon or nitrocellulose
(Southern blotting).
Hybridisation with the help of a radiolabelled VNTR
probe. These proteins target a specific nucleotide
sequence that is complementary to them.
n
n
At last, the genetic and physical maps of the genome were
constructed by collecting information about certain repetitive
DNA sequences and DNA polymorphism.
n
n
n
Salient Features/Observations of Human
Genome
Å
Å
Å
Å
Å
There are 3164.7 million nucleotide bases in the human
genome.
In an average gene, there are 3000 bases. The largest known
human gene is Dystrophin (2.4 million bases).
Total number of genes in human genome are estimated at
30, 000. Almost, all (99.9%) of the nucleotide bases are exactly
same in every human individual.
For over 50% of the discovered genes, the functions are
unknown.
Less than 2% of the genome codes for proteins.
NEET
n
n
Autoradiography Detection of hybridised DNA
fragments by autoradiography.
Applications of DNA Fingerprinting
Å
Å
Å
It helps to settle paternity or maternity disputes.
It is used to identify perpetrators of sexual assault cases.
It is used identify racial groups.
KEY NOTES
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CHAPTER 06 > Molecular Basis of Inheritance
131
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1 ~ The DNA
10 Which of the following are all nucleotides?
1 DNA is a
(a)
(b)
(c)
(d)
long polymer of deoxyribonucleotides
short polymer of deoxyribonucleotides
monomer polymer of deoxyribonucleotides
long polymer of ribonucleotides
11 A polymer or a polynucleotide chain has at one end a
2 The length of DNA usually depends on
(a)
(b)
(c)
(d)
free ........A....... at 5′ end of sugar, similarly at the
other end of the polymer the sugar has a free .....B.....
of 3′ group.
position of nucleotides
number of nucleotides
Both (a) and (b)
None of the above
3 Find the incorrect match.
(a) A bacteriophage (φ × 174) –5386 nucleotides
(b) Bacteriophage lamda – 48502 base pairs
(c) E. coli – 4.6 × 106 bp
(d) Haploid content of human DNA – 3.3 × 10 bp
6
4 Purines found both in DNA and RNA are NEET 2019
(a) adenine and guanine
(c) cytosine and thymine
(b) guanine and cytosine
(d) adenine and thymine
5 Nitrogenous bases are linked to sugar by
(a) hydrogen bond
(c) N-glycosidic bond
(b) phosphodiester bond
(d) O-glycosidic bond
6 Nucleoside is formed when the nitrogenous bases are
linked to
(a) sugar
(c) proteins
(b) phosphate
(d) fats
7 What is the difference between adenosine and
deoxyadenosine?
(a) Only sugar
(c) Only phosphate
(a) Adenosine, cytidilic acid, cytosine
AIIMS 2019
(b) Adenylic acid, cytidilic acid, guanylic acid
(c) Cytidine, adenine, adenylic acid
(d) Uracil, thymidine, thymidylic acid
(b) Only purine
(d) All of these
8 When a phosphate group is linked to ...A... group of
nucleoside through ...B... bond, a corresponding ...C...
is formed.
Choose the correct option for A, B and C.
(a) A–5′ OH, B–phosphodiester bond, C–nucleotide
(b) A–3′ OH, B–phosphodiester bond, C–nucleotide
(c) A–2′ OH, B–phosphodiester bond, C–nucleotide
(d) A–5′ OH, B–phosphodiester bond, C–nucleoside
9 Choose the correct option.
(a) Pyrimidines include adenine and guanine
(b) Pyrimidines include cytosine, uracil and thymine
(c) Purines include adenine and thymine
(d) Purines include guanine and cytosine
(a) A – Phosphate moiety, B – OH
(b) A – OH, B – Phosphate moiety
(c) A – COOH, B – Phosphate moiety
(d) A – Phosphate moiety, B–COOH
12 Backbone of DNA is formed by
(a)
(b)
(c)
(d)
sugar
phosphates
Both (a) and (b)
nitrogenous bases (purine and pyrimidine)
13 Thymine is also called
(a) 2 methyl uracil
(c) 4 methyl uracil
(b) 3 methyl uracil
(d) 5 methyl uracil
14 Choose the incorrect option.
(a) Friedrich Miescher in 1869 identified DNA as an acidic
substance and named it nuclein
(b) Erwin Chargaff said, the ratio between A and T and G
and C of dsDNA are constant and equals one
(c) The two strands of dsDNA are complementary to each
other
(d) None of the above
15 X-ray data diffraction of DNA was produced by
(a) Watson and Crick
(c) Bateson and Punnett
(b) Wilkins and Franklin
(d) Both (a) and (b)
16 In DNA 20% bases are adenine. What percentage of
bases are pyrimidines?
(a) 30%
(b) 60%
JIPMER 2019
(c) 50%
(d) 20%
17 In sea urchin DNA, which is double-stranded 17% of
the bases were shown to be cytosine. The percentages
of the other three bases expected to be present in this
CBSE-AIPMT 2015
DNA are
(a)
(b)
(c)
(d)
G/34%, A/24.5%, T/24.5%
G/17%, A/16.5%, T/32.5%
G/17%, A/33%, T/33%
G/8.5%, A/50%, T/24.5%
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18 In the given diagram of chemical structure of DNA,
identify the type of bonding shown by A, B and C.
H O
H
3′
H
HO
5′
H 2C
1
3
N
O
9
4
2
2
B
O
C
HO—P== O
O== P—OH
N
H
5
6
3
2
1N
4
3′
5′
O
O
H
H
O
Cytosine
O
N
O
1
6
5
2
3
N1
H
O
8
9
N
4
N
CH2
5′
3′
Guanine
N
O
H
HO
Deoxyribose
H
3′
O== P—OH
H
20 Which of the following is not the correct salient
feature of double-helix structure of DNA?
H
Deoxyribose
A
O
CH2
5′
N
3′
H
H2 C
O
3
N
Adenine
O
Thymine
O
8
N1
NH
O
7
5
6
6
4
1
4
5′
5
2
3′ 3
HO—P== O
N
N
H 3C
(a) A–0.34 Å, B–20 Å, C–3.4 Å, D–Phosphate backbone,
E–Major groove, F–Minor groove
(b) A–3.4 Å, B–20 Å, C–34 Å, D–Sugar backbone,
E–Major groove, F–Minor groove
(c) A–34 Å, B–20 Å, C–3.4 Å, D–Sugar phosphate
backbone, E–Major groove, F–Minor groove
(d) A–34 Å, B–20 Å, C–0.34 Å, D–Major groove,
E–Minor groove, F–Sugar phosphate bone
(a) Two polynucleotide chains have backbone of sugar
and phosphate and bases project inside
(b) Two chains have antiparallel polarity, i.e. one is
5′→ 3′ and other is 3′→ 5′
(c) Adenine forms three hydrogen bonds with thymine
and guanine forms two hydrogen bonds with cytosine
(d) The plane of one base pair stacks over the other in
double helix in addition to H-bond to confer extra
statbility to helical structure
21 The diagram shows an important concept in the
genetic implication of DNA. Fill in the blanks A to
C.
NEET 2013
Proposed by C
O
(a) A–N-glycosidic bonding, B–Phosphodiester bonding,
C–Hydrogen bonding
(b) A–N-glycosidic bonding, B–Phosphodiester bonding,
C–Covalent bonding
(c) A–N-glycosidic bonding, B–Phosphodiester bonding,
C–Coordinate bonding
(d) A–N-glycosidic bonding, B–Hydrogen bonding,
C–Phosphodiester bonding
19 Given the diagram showing Watson and Crick model of
DNA structure. Identify the parameters of A, B and C.
B
Guanine
Cytosine
C
G
Thymine
Adenine
A
T
C G
DNA
A
mRNA
B
Protein
(a) A–transcription, B–replication, C–James Watson
(b) A–translation, B–transcription, C–Erwin Chargaff
(c) A–transcription, B–translation, C–Francis Crick
(d) A–translation, B–extension, C–Rosalind Franklin
22 In some viruses, the flow of information is in
reverse direction, i.e. from RNA to DNA. Can you
suggest a simple name to the process?
(a) Transcription
(b) Transception
(c) Reverse transcription (d) Translation
23 The length of DNA in a human cell is about
(a) 2.3 m
(b) 2.4 m
(c) 2.2 m
(d) 2.0 m
24 Find out the number of base pairs in E. coli DNA if
T
its DNA is 1.36 mm long.
A
A
C
G
T
A
E
G
D
C
G
C
C
T
G
A
Hydrogen bonds
5′
(b) 3 × 106 bp
(d) 7 × 106 bp
25 In prokaryotes (such as E. coli) ...A... nucleus is not
A
F
(a) 4 × 106 bp
(c) 2 × 106 bp
3′
present, the DNA is not scattered throughout the
cell. DNA is ...B... charged and holded by the ...C...
charged proteins. This structure in prokaryotes is
called ...D... .
Choose the correct option for A, B, C and D.
(a)
(b)
(c)
(d)
A–undefined, B–negatively, C–positively, D–nucleoid
A–undefined, B–negatively, C–positively, D–nucleus
A–defined, B–negatively, C–positively, D–nucleoid
A–defined, B–positively, C–negatively, D–nucleoid
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CHAPTER 06 > Molecular Basis of Inheritance
26 Positively charged basic proteins that are found in
133
31 In the given diagram, identify A, B and C.
eukaryotes are called
(a) histones
(c) arginine
B
A
(b) protamine
(d) lysine
27 Choose the incorrect pair.
(a) Basic amino residues in histones — Lysine and arginine
(b) Unit of 8 molecules in histones — Histone octamer
(c) Negative charged DNA wrapped around positive
charged DNA — Nucleosome
(d) Thread-like, colourless unit of structure — Chromatin
in nucleus
28 Linker-DNA is attached to
(a) H1
(b) H2A
JIPMER 2018
(c) H2B
(d) H3
29 The packaging of chromatin at higher level requires
an additional set of proteins that are collectively
referred to as
(a) histone proteins
(c) basic proteins
(b) non-histone proteins
(d) acidic packaging proteins
30 The association of histone H1 with a nucleosome
indicates
NEET 2017
(a) transcription is occurring
(b) DNA replication is occurring
(c) the DNA is condensed into chromatin fibre
(d) the DNA double helix is exposed
C
Core of histone molecules
(a)
(b)
(c)
(d)
A–DNA, B–H1 histone, C–Histone octamer
A–RNA, B–H1 histone, C–Histone octamer
A–DNA, B–H1 histone, C–Histone tetramer
A–RNA, B–H1 histone, C–Histone tetramer
32 Lightly stained part of chromatin which remains
loosely packed and is transcriptionally active named as
(a)
(b)
(c)
(d)
euchromatin
heterochromatin
chromatosome
chromonemata
33 Part of chromatin which is densely packed, stain
darkly and is transcriptionally inactive is called
(a) euchromatin
(c) heterochromatin
(b) chromatosome
(d) chromosome
TOPIC 2 ~ The Search for Genetic Material and RNA World
34 Experimental organism of Frederick Griffith was
(a) Variola virus
(c) Actinomycetes
(b) Tuberculosis bacteria
(d) Streptococcus pneumoniae
35 What was unique in Griffith’s experiments?
(a) DNA was found to be the genetic material
(b) RNA was found to be the genetic material
(c) Something from dead organisms could change the
living cells
(d) Viruses can live in bacteria
36 In Griffith experiment, what would be the effect of
following conditions on mice?
Form of Pneumococcus Injected
I.
II.
III.
IV.
Effect on Mice
Live R-strain
Live S-strain
Heat-killed S-strain
Heat-killed S-strain + live R-strain
A
B
C
D
Choose the correct option for effect on mice.
(a) A–Survived, B–Died, C–Died, D–Survived
(b) A–Survived, B–Died, C–Survived, D–Died
(c) A–Died, B–Survived, C–Survived, D–Died
(d) A–Died, B–Survived, C–Died, D–Died
37 Which scientist experimentally proved that DNA is
the sole genetic material in bacteriophage?
NEET (Odisha) 2019, 17
(a) Beadle and Tatum
(c) Hershey and Chase
(b) Meselson and Stahl
(d) Jacob and Monod
38 Isotopes used by Hershey and Chase were
(a)
(c)
32
34
P and 35S
P and 31S
(b)
(d)
35
30
P and 32S
P and 32S
39 Bacteriophage nucleic acids were labelled as
(in Hershey and Chase experiment)
(a)
(c)
32
35
P labelled phosphate (b) 3 H labelled H2O
S labelled sulphate (d) 14 C labelled CO2
40 Bacteriophage protein coat was labelled by growing
E. coli on
(a)
(b)
(c)
(d)
radioactive sulphur-35
radioactive sulphur-32
radioactive sulphur-30
radioactive phosphorus-32
41 Hershey and Chase concluded that viral infecting
agent in their experiment was
(a) Protein
(c) RNA
(b) DNA
(d) Both (b) and (c)
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Master The NCERT > BIOLOGY (Vol-II )
134
S and 32P to prove that
DNA is the genetic material. Their experiments proved
that DNA is genetic material because
42 Hershey and Chase used
35
(a) progeny viruses retained 32P but not 35S
(b) retention of 32P in progeny viruses indicated that
DNA was passed on
(c) loss of 35S in progeny viruses indicated that proteins
were not passed on
(d) All of the above
43 RNA is the genetic material in
(a)
(b)
(c)
(d)
All bacteria
Tobacco Mosaic Viruses (TMV)
QB bacteriophage
Both (b) and (c)
44 A molecule that can act as a genetic material must
fulfill the traits given below, except
NEET 2016
(a) it should be able to express itself in the form of
‘Mendelian characters’
(b) it should be able to generate its replica
(c) it should be unstable structurally and chemically
(d) it should provide the scope for slow changes that are
required for evolution
45 Which group present in RNA nucleotide is very
reactive and makes RNA liable and easily degradable
than DNA?
(a)
(b)
(c)
(d)
3–OH′ group at every nucleotide
2–OH′ group on ribose sugar
3–OH′ group on ribose sugar
4–OH′ group on ribose sugar
46 Stability of DNA is due to
(a)
(b)
(c)
(d)
deoxyribose sugar
presence of thymine in place of uracil
Both (a) and (b)
None of the above
47 Viruses having RNA genome and having shorter
lifespan, mutate and evolve faster because
(a)
(b)
(c)
(d)
RNA is unstable and mutates at faster rate
RNA is stable and mutates at faster rate
RNA is stable and mutates at slower rate
RNA is unstable and mutates at slower rate
48 DNA is dependent on ...A... for synthesis of proteins.
DNA and RNA both can function as genetic
material. But ...B... being more stable, preferred for
the storage of genetic information. For the
transmission of genetic information, ...C... is better.
Choose the correct option for A, B and C.
(a) A–DNA, B–RNA, C–RNA
(b) A–RNA, B–DNA, C–RNA
(c) A–RNA, B–RNA, C–DNA
(d) A–DNA, B–RNA, C–DNA
49 The first genetic material was
(a)
(b)
(c)
(d)
RNA
DNA
Both (a) and (b)
None of the above
50 Which one of the following is not applicable to RNA?
(a)
(b)
(c)
(d)
Complementary base pairing
CBSE-AIPMT 2015
5′ phosphoryl and 3′ hydroxyl ends
Heterocyclic nitrogenous bases
Chargaff’s rule
51 Which one of the following option is correct?
(a) DNA has evolved from RNA with chemical
modifications
(b) DNA being complementary double-stranded resists
changes by a process of repair
(c) RNA being a catalyst is reactive and unstable
(d) All of the above
TOPIC 3 ~ Replicaton
52 DNA replication is semiconservative. It was shown
(a) fungi
(b) E. coli
(c) Vicia faba (d) algae
53 Who experimentally proved the semiconservative
(a) AgCl density gradient (b) CaSO4 density gradient
(c) CsCl density gradient (d) KCl density gradient
56 In Meselson and Stahl’s experiment (1958), DNA
mode of DNA replication?
(a)
(b)
(c)
(d)
55 Heavy DNA can be differentiated from normal DNA
by which centrifugation technique?
first in
extracted from the culture one generation after the
transfer from 15 N to 14 N medium had a hybrid
(or intermediate) density. Why?
Mathew Meselson
Franklin Stahl
Both (a) and (b)
Watson and Crick
54 Name the heavy isotope used by Meselson and Stahl
for proving the semiconservative mode of DNA.
14
(a)
15
NH4 Cl
(b)
(c)
13
NH2 Cl 3
(d) All of these
NH3 Cl 2
(a) Because the generation time of E. coli (culture) was
about 20 minutes
(b) Because it would take 20 minutes for RNA replication
(c) Because it would take 20 minutes for replication of
DNA to RNA (transcription)
(d) Because it would take 20 minutes for translation RNA
to protein
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CHAPTER 06 > Molecular Basis of Inheritance
57 Given diagram depicts the experiment of Meselson
and Stahl. Identify the type of isotopic DNA formed
after 40 minutes (A, B, C and D).
Generation-I
14N-DNA
135
63 Replication occurs within the small opening of DNA
helix referred to as
(a) replication fork
(c) DNA fork
(b) duplication fork
(d) RNA fork
64 DNA-dependent DNA polymerases catalyses
15N-DNA
polymerisation in which direction?
15N-DNA
40 min
20 min
(a) 3′ → 5′
(c) 5′ → 3′
(b) 5′ → 2′
(d) 2′ → 5′
65 On which strand of DNA, replication is continuous?
Generation-II
A-DNA
B-DNA
C-DNA
D-DNA
(a)
(b)
(c)
(d)
5′ → 3′ polarity strand
3′ → 5′ polarity strand
3′ → 2′ polarity strand
3′ → 4′ polarity strand
66 Identify A, B and C strands.
5′ 3′
(a)
(b)
(c)
(d)
A–14 N-DNA, B–15 N-DNA, C–14 N-DNA, D–15 N-DNA
A–14 N-DNA, B–15 N-DNA, C–14 N-DNA, D–14 N-DNA
A–14 N-DNA, B–14 N-DNA, C–15 N-DNA, D–15 N-DNA
A–14 N-DNA, B–15 N-DNA, C–15 N-DNA, D–15 N-DNA
C
58 Similar experiments like Meselson and Stahl was
performed by Taylor in 1958. The experimental
organism of Taylor was
(a) Vicia faba
(c) E. coli
(b) Fungi
(d) Protista
59 Radioisotope used by Taylor in his experiment was
(a) iron
(c) thymidine
(b) titanium
(d) copper
3′
5′
(a) A–Continuous strand, B–Discontinuous strand,
C–Template strand
(b) A–Leading strand, B–Lagging strand, C–Parental strand
(c) A– 5′−3′ strand, B– 3′−5′ strand, C–Parental strand
(d) All of the above
(a) primase
(c) DNA topoisomerase
(b) polymerase
(d) SSBPs
68 During DNA replication, okazaki fragments are used
to elongate
61 DNA polymerisation rate of DNA polymerase is
(b) 2000 bp/s
(d) 5000 bp/s
62 For long DNA molecules, the two strands of DNA
cannot be separated in its entire length due to the
requirement of
(a)
(b)
(c)
(d)
B
Newly
synthesised
strands
JIPMER 2019
DNA dependent
DNA independent
RNA dependent
RNA independent
(a) 1000 bp/s
(c) 3000 bp/s
3′5′
5′
67 During DNA replication, supercoiling is relaxed by
60 DNA polymerase is
(a)
(b)
(c)
(d)
3′
A
enzymes
high energy
RNA
phosphate and nucleotide
NEET 2017
(a) The leading strand towards replication fork
(b) The lagging strand towards replication fork
(c) The leading strand away from replication fork
(d) The lagging strand away from the replication fork
69 Deoxyribonucleoside triphosphate serve dual
purposes. The purposes are
(a) act as substrate and decrease reaction rate
(b) provide energy for polymerisation and act as substrate
(c) decrease reaction rate and provide energy for
polymerisation
(d) Synthesise RNA primer and decrease reaction rate
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Master The NCERT > BIOLOGY (Vol-II )
136
TOPIC 4~ Transcription
70 Which one of the following is wrongly matched?
Codes
CBSE-AIPMT 2014
(a) Transcription – Writing information from DNA to
t RNA
(b) Translation–Using information in mRNA to make
proteins
(c) Repressor protein – Binds to operator to stop enzyme
synthesis
(d) Operon – Structural genes, operator and promoter
71 Why both the strands of DNA are not copied during
transcription?
(a) Because RNA molecule with different sequences will
be formed
(b) Because RNA molecule with same sequences will be
formed
(c) Because RNA molecule with identical sequences will
be formed
(d) Because DNA molecule with different sequences will
be formed
72 If both the strands copied during transcription, then
what will happen?
73 What will happen if the double-stranded RNA is
produced during transcription?
(a) This would prevent RNA from being translated into
protein
(b) This would not prevent RNA from being translated into
protein
(c) There will be the continuous synthesis of RNA
(d) Double-stranded RNA will have lower stability. It will
be degraded very fastly
74 Which strand of DNA works as template strand?
(a) 5′ – 3′ polarity strand (b) 3′ – 5′ polarity strand
(c) Both (a) and (b)
(d) None of these
75 The strand which do not code for anything is called
(a) coding strand
(c) template strand
(b) non-coding strand
(d) antisense strand
76 In given diagram find out
Transcription start site
5
5′
A. Promoter site
C. Terminator site
E. Coding strand
A
5
5
5
5
B
1
1
4
4
C
4
4
1
1
D
2
3
2
3
E
3
2
3
2
77 If the coding strand has the sequence
5 ′–ATCGATCG–3′ then find out the sequence of
non-coding strand.
(a)
(b)
(c)
(d)
3′ − TAGCTAGC − 5 ′
5′− TACGTACG − 3 ′
5′− UAGGUACG − 3 ′
5′− UACFUACG − 3 ′
78 AGGTATCGCAT is a sequence from the coding
strand of a gene. What will be the corresponding
sequence of the transcribed mRNA?
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(a) ACCUAUGCGAU
(c) AGGUAUCGCAU
(b) UGGTUTCGCAT
(d) UCCAUAGCGUA
79 Which of the following mRNA can be transcripted?
(a) The segment of DNA would be coding for two different
proteins
(b) Two RNA will be produced simultaneously
complementary to each other
(c) There will be formation of double helical RNA
(d) All of the above
3′
(a)
(b)
(c)
(d)
4
2
5′
B. Structural gene
D. Template strand
(b) UAA.UAV.UGG
(d) UGA.UUV.UGG
80 What will be the sequence of mRNA produced by the
following stretch of DNA?
3'–ATGCATGCATGCATG–5' Template strand
5'–TACGTACGTACGTAC–3' Coding strand
(a) 3' – AUGCAUGCAUGCAUG–5' NEET (Odisha) 2019
(b) 5' – UACGUACGUACGUAC–3'
(c) 3' – UACGUACGUACGUAC–5'
(d) 5'– AUGCAUGCAUGCAUG–3'
81 Promoter and terminator flanks the
(a) house-keeping gene
(c) recon
(b) structural gene
(d) transcription unit
82 Choose the incorrect pair.
(a)
Promoter
(b)
Terminator — Define the end of transcription process
— Binding site for RNA polymerase
(c)
Cistron
— Segment of RNA coding for a
polypeptide
(d)
Regulatory
genes
— Do not code for any RNA or protein
83 Identify the correct pair of mRNA type and its
1
3
JIPMER 2018
(a) AUG.UGA.UUU
(c) UAG.UGA.UUV
3′
function.
(a) Messenger RNA — Provides the template
(b) Transfer RNA — Brings amino acids and reads genetic
code
(c) Ribosomal RNA — Plays catalytic role during translation
(d) All of the above
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CHAPTER 06 > Molecular Basis of Inheritance
84 Which of the following RNAs should be most
abundant in animals cell?
(a) rRNA
(b) tRNA
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(c) mRNA
(d) miRNA
85 DNA-dependent RNA polymerase catalyses
137
92 In splicing, the sequences which are kept and those
which are removed, respectively, are
(a) exons and introns
(c) exons and cistrons
(b) introns and exons
(d) introns and cistrons
transcription on one strand of the DNA which is
called the
NEET 2016
93 Spliceosomes are not found in cells of
(a) template strand
(c) alpha strand
94 Name the nucleotide added to 5′ end of hnRNA in
(b) coding strand
(d) anti-strand
of all types of RNA (mRNA, tRNA and rRNA)?
DNA-dependent RNA polymerase
DNA-dependent DNA polymerase
RNA-dependent RNA polymerase
RNA-dependent DNA polymerase
(b) Elongation
(d) Aminoacylation
88 What initiation and termination factors are involved
in transcription in eukaryotes?
NEET (Odisha) 2019
(b) α and β, respectively
(d) α and σ, respectively
89
3′
(A)
RNA polymerase
(B)
(C)
5′
5′
3′
RNA
Polymerase
Rho factor
3′
5′
RNA
σ
Terminator
Identify A, B and C.
AIIMS 2019
(a) A–Elongation, B–Termination, C–Initiation
(b) A–Initiation, B–Termination, C–Elongation
(c) A–Initiation, B–Elongation, C–Termination
(d) A–Termination, B–Elongation, C–Initiation
90 In bacteria, transcription and translation takes place in
the same compartment. Why?
(a) No separation of cytosol and nucleus
(b) mRNA does not require any processing to become
active
(c) Both (a) and (b)
(d) Due to the presence of nucleus
91 In the process of transcription in eukaryotes, the RNA
polymerase-I transcribes
(a)
(b)
(c)
(d)
96 What happens in the tailing process of transcription?
(a)
(b)
(c)
(d)
Adenylate residues added at 5′ end of RNA
Adenylate residues added at 3′ end of RNA
Guanylate residues added at 5′ end of RNA
Guanylate residues added at 3′ end of RNA
97 Fully processed hnRNA to undergo translation is
called
(b) rRNA
(c) tRNA
(d) sRNA
5′
3′
5′
3′
A
Capping
B
Cap
5′
3′
(b) Modified C at 5′
(d) Poly-C
(a) Poly-A tail
(c) 7 mG
transcription in eukaryotes. Identify A, B, C and D.
3′
ρ
Ethyl cytosine triphosphate
Ethyl guanosine triphosphate
Methyl guanosine triphosphate
Methyl cytosine triphosphate
98 The following diagram refers to the process of
Sigma factor
RNA
(a)
(b)
(c)
(d)
(a) mRNA
3′
5′
DNA helix
5′
Promoter σ
(d) bacteria
JIPMER 2018
catalysed by RNA polymerase only?
(a) σ and ρ, respectively
(c) β and γ, respectively
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(c) animals
95 Which is present at 5′ end of eukaryotic mRNA?
87 In prokaryotes, which process of transcription is
(a) Initiation
(c) Termination
(b) fungi
capping.
86 In bacteria, which enzyme catalyses the transcription
(a)
(b)
(c)
(d)
(a) plants
NEET (Odisha) 2019
mRNA with additional processing, capping and tailing
tRNA, 5 srRNA and snRNAs
rRNAs-28 S, 18 S and 5.8 S
precursor of mRNA, hnRNA
mG
ppp
C
5′ m
Gppp
5′
RNA splicing
mG
ppp m
Gppp
5′
5′
Messenger RNA (mRNA)
3′ mRNA
Polyadenylation
or tailing
3′
D
3′
(a) A–RNA polymerase-II, B–Exon, C– Intron, D–Poly-A
tail
(b) A–RNA polymerase-III, B–Intron, C– Exon, D–Poly-A
tail
(c) A–RNA polymerase-II, B–Intron, C– Exon, D–Poly-A
tail
(d) A–RNA polymerase-III, B–Intron, C– Exon, D–Poly-G
tail
99 Choose the correct option.
(a) Splicing represent the dominance of RNA world
(b) The presence of introns is reminiscent of antiquity
(c) Split gene arrangements represent an ancient feature of
the genome
(d) All of the above
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138
TOPIC 5 ~ Genetic Code
100 Genetic code
112 From the following, identify the correct combination
(a) is a relationship between sequence of DNA or mRNA to
polypeptide
(b) triplet base on mRNA
(c) determines the sequence of amino acid in polypeptide
(d) All of the above
101 In order to code for all the 20 amino acids, the code
should be made up of three nucleotides.
This statement was suggested by
(a) Har Gobind Khorana
(c) Marshall Nirenberg
(b) George Gamow
(d) Servo Ochoa
molecules with well-defined combination of bases
(homopolymers and copolymers) to develop genetic
code?
(b) Har Gobind Khorana
(d) Nirenberg
103 Who used cell free system for protein synthesis?
(a) Marshall Nirenberg
(c) Khorana
(b) Ochoa
(d) Gamow
104 Polynucleotide phosphorylase enzymes are also called
(b) Servo Ochoa enzymes
(a) Crick et. al enzymes
(c) James Watson enzymes (d) Mendel enzymes
105 How many codons codes for amino acids?
(a) 25
(b) 50
(c) 61
(d) 60
106 The genetic codes of arginine are
(a) CGU, CGC, CGA
(c) AGU, AGC, AAC
AIIMS 2019
(b) CAU, CAC, CAA
(d) GAU, GAC, GAA
107 Codons of glycine are
AIIMS 2018
(a) CCU, CCC, CCA, CCG
(b) CGU, CGC, CGA, CGG
(c) GGU, GGC, GGA, GGG
(d) ACU, ACC, ACA, ACG
(b) histidine
(d) alanine
JIPMER 2019
(b) UAC
(c) UAG
(d) UGA
110 The one aspect, which is not a salient feature of
genetic code is, its being
(a) degenerate
(c) universal
(b) ambiguous
(d) specific
111 Codons are non-ambiguous, which means that one
codon codes for
(a)
(b)
(c)
(d)
more than one amino acid
two amino acids
Only one amino acid
non-sense amino acid
114 Which of the following features of genetic code does
allow bacteria to produce human insulin by
recombinant DNA technology?
NEET 2019
(a) Genetic code is redundant
(b) Genetic code is nearly universal
(c) Genetic code is specific
(d) Genetic code is not ambiguous
115 The relationship between genes and DNA are best
understood by
(a)
(b)
(c)
(d)
mutation
recombination
enzymatic synthesis of amino acid
enzymatic synthesis of codons
116 Sickle-cell anaemia is a classical example of point
mutation in which valine amino acid comes in
place of
(a) glutamate (b) tryptophane (c) alanine (d) guanine
no change in the reading frame of following mRNA?
NEET 2019
5′–AACAGCGGUGCUAUU–3 ′
109 Which of the following is not a stop condon?
(a) UAA
(a) one amino acid has more than one code triplet
(b) one amino acid has only one code triplet
(c) codons which specify the same amino acids differ only
in the third base of the triplet
(d) Both (a) and (c)
117 Under which of the following conditions will there be
108 The codon AUG codes for (in eukaryotes)
(a) methionine
(c) tryptophan
NEET (Odisha) 2019
(a) Universal, non-ambiguous, overlapping
(b) Degenerate, overlapping, commaless
(c) Universal, ambiguous, degenerate
(d) Degenerate, non-overlapping, non-ambiguous
113 Degeneracy refers to
102 Who developed the technique of synthesising RNA
(a) Crick et. al
(c) Matthaei
of salient features of genetic code.
(a) Deletion of G from 5th position
(b) Insertion of A and G at 4th and 5th positions,
respectively
(c) Deletion of GGU from 7th, 8th and 9th positions
(d) Insertion of G at 5th position
118 If there are 999 bases in an RNA that codes for a
protein with 333 amino acids and the base at position
901 is deleted such that the length of the RNA
becomes 998 bases, how many codons will be
NEET 2017
altered?
(a) 1
(c) 33
(b) 11
(d) 333
119 Which mutation of the genetic bases gives the proof
that codon is triplet and reads in a contagious
manner?
(a) Frameshift mutation
(c) Both (a) and (b)
(b) Point mutation
(d) Inversion mutation
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CHAPTER 06 > Molecular Basis of Inheritance
120 The presence of an adapter molecule that would on
one hand read the code and on other hand would bind
to specific amino acids was postulated by
(a) Francis Crick
(c) Rosalind Franklin
(b) James Watson
(d) Griffith
121 Before the genetic code was postulated, the tRNA
was called
(a)
(b)
(c)
(d)
rRNA (ribosomal RNA)
mRNA (messenger RNA)
sRNA (soluble RNA)
sRNA (sedimentary RNA)
(a) A–Variable arm, B–D-loop, C–T-loop, D–Anticodon
arm, E–Codon, F–Variable arm
(b) A–Amino acid arm, B–T-loop, C–Variable arm,
D–Anticodon arm, E–Codon, F–D- loop
(c) A–Amino acid arm, B–T-loop, C–Anticodon loop,
D–Anticodon, E–Codon, F–D-loop
(d) A–Amino acid arm, B–T-loop, C–Anticodon loop,
D–Anticodon, E–Codon, F–Variable arm
123 Choose the incorrect option for tRNA molecule.
122 Study the given figure and identify A to F.
Tyr
A
(a) It has an anticodon loop that has bases complementary
to the code
(b) It has an amino acid acceptor end to which it binds to
amino acids
(c) tRNA are not specific for each amino acid
(d) tRNA looks like a clover leaf
124 tRNA is a compact molecule which looks like
(a) M-shaped (b) P-shaped (c) L-shaped (d) K-shaped
F
125 RNA binds to mRNA through
B
A
U
U G
A C
JIPMER 2019
(a) anticodon loop
(b) T ψ C loop
(c) amino acid binding loop
(d) D-loop
C
D
E mRNA
126 Removal of RNA polymerase-III from nucleoplasm
will affect the synthesis of
3¢
(a) tRNA
CBSE-AIPMT 2012
(b) hnRNA (c) mRNA
(d) rRNA
TOPIC 6 ~ Translation
127 The process of polymerisation of amino acids to form
a polypeptide is
(a) transcription
(c) translation
(b) replication
(d) polymerisation
128 Many ribosomes may associate with a single mRNA
to form multiple copies of a polypeptide
simultaneously. Such strings of ribosomes are termed
as
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(a) plastidome
(c) polysome
(b) polyhedral bodies
(d) nucleosome
129 In the protein synthesis, tRNA carrying the amino
acid enters from which site of the ribosome?
(a) A-site
(c) Anticodon site
(b) P-site
(d) R-site
130 The order and sequences of amino acids are defined
by the sequences of the bases in
(a) rRNA
(b) mRNA (c) tRNA
(d) All of these
131 Which of the following enzymes are required in
protein synthesis?
I. Ligase
II. Permease
IV. Ribozyme
III. Endonuclease
V. RNA polymerase
VI. Peptidyl transferase
VII. Amino acid activating enzyme
Choose the correct option.
(a) IV, VI and VII
(c) II, III, IV and V
(b) I, II and III
(d) All of these
132 Which among the following process occur(s) during
charging or aminoacylation of tRNA?
(a)
(b)
(c)
(d)
Activation of amino acids in the presence of ATP
Linking of amino acids to their cognate tRNA
Both (a) and (b)
None of the above
133 The cellular factory responsible for the synthesis of
proteins is
(a)
(b)
(c)
(d)
mitochondria
endoplasmic reticulum
Golgi body
ribosome
134 Which of the following rRNAs act as structural RNA
as well as ribozyme in bacteria?
(a) 5 srRNA
(c) 23 srRNA
NEET 2016
(b) 18 srRNA
(d) 5.8 srRNA
135 UTRs present on mRNA refer to
(a)
(b)
(c)
(d)
Untranscribed regions at both 5′ end and 3′ end
Untranslated regions at 5′ end
Untranslated regions at both 5′ end and 3′ end
Untranslated regions at 3′ end
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Master The NCERT > BIOLOGY (Vol-II)
140
136 For initiation, the ribosomes binds to the ...A... at the
start codon and ...B... is recognised by the ...C... .
Choose the correct option for A, B and C.
(a)
(b)
(c)
(d)
A–mRNA, B–AUG, C–initiator tRNA
A–mRNA, B–AUG, C–tRNA
A–rRNA, B–AUG, C–tRNA
A–rRNA B–AUG, C–initiator mRNA
140 Study the diagram given below of translation and
choose the correct option for labels A, B, C, D and E.
Gly
Leu
Tyr
Growing
polypeptide chain
Ser
Leu
A
—
Kind to stop codon for
terminating translation
(c)
Translational
unit
—
Sequence of RNA with start
codon only
(d)
Elongation phase —
Ribosome moves from codons
to codons along mRNA
138 For the given DNA sequence
3′–TACATGGGTCCG–5′.
Choose the correct sequential code of tRNA
anticodon.
I. UAC
II. AUG
III. GGC
IV. CCA
(a) I, II, III and IV
(c) I, III, II and IV
(b) II, III, IV and I
(d) II, I, IV and III
139 RNA molecule
I
II
III
IV
Anti-codon pairing
UCA
AUG
AUU
AUC
Which of the following tRNA molecules does not
exist?
(b) II and III (c) III and IV (d) IV and I
G
Release factor
G
(b)
B
Ser
E
Val
tRNA
tRNA
A
Required for efficient
translation process
A
—
Asn
U
Untranslated
regions
Transferase enzyme
forming peptide bond
U
(a)
A-site
(Amino acyl tRNA site)
Gly
137 Choose the incorrect pair.
(a) I and II
P-site
(Peptidyl tRNA site)
CGU CAA
Amino acid
tRNA complex
Large ribosomal
subunit
C U C U UGGGU C CGC A G U U A AU U U C A U C
D
C
mRNA
Ribosome
A
B
(a) Charged/
Uncharged tRNA
Aminoacylated
tRNA
Small ribosomal subunit
C
D
E
5′ end 3′ end
Glycine
(b) Uncharged
tRNA
Charged/Aminoacy- 5′ end 3′ end
lated tRNA
Alanine
(c) Uncharged
tRNA
Charged/Aminoacy- 3′ end 5′ end
lated tRNA
Glycine
(d) Uncharged
tRNA
Charged/Aminoacy- 5′ end 3′ end
lated tRNA
Lysine
141 Termination of protein synthesis or translation
requires
(a) Both stop signal and starting codon
(b) Both starting codon and release factor
(c) Both release factor and stop codon
(d) GUG and AUG codon
TOPIC 7 ~ Regulation of Gene Expression
142 The regulation of gene expression in eukaryotes can be
exerted at
I. transcriptional level.
II. processing level.
III. transport of mRNA (from nucleus to cytoplasm).
IV. translational level.
Choose the correct combination to complete the
statement.
(a) I and II
(c) III and IV
(b) II and III
(d) All of these
143 In prokaryotes, control of the rate of ...A... is the
pre-dominant site for the control of gene expression.
In a transcription unit, the activity of ...B... at a given
promoter is in turn regulated by interaction with ...C...
proteins, which affects its ability to recognise the start
sites.
Complete the statement filling the correct options in
given blanks.
(a) A–RNA replication, B–DNA polymerase, C–accessory
(b) A–transcriptional initiation, B–RNA polymerase,
C–accessory
(c) A–translational initiation, B–RNA polymerase,
C–accessory
(d) A–DNA replication, B–RNA polymerase, C–accessory
144 Positively regulatory proteins are called
(a)
(b)
(c)
(d)
activator
repressors
necessary proteins
accessory proteins
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CHAPTER 06 > Molecular Basis of Inheritance
145 The accessibility of the promoter regions of
prokaryotic DNA is (in many cases) regulated by the
interaction of proteins with the sequences termed as
(a) regulator
(c) operator
(b) promoter
(d) structural genes
146 An operon is considered to regulate a
(a) translational unit
(c) protein unit
(b) genetic unit
(d) enzymatic unit
153 Lactose is a substrate for
147 1st operon model was
(b) lac operon
(d) val operon
(a) trp operon
(c) his operon
148 Select the correct match.
(a)
(b)
(c)
Matthew Meselson and F Stahl
Alfred Hershey and Martha Chase
Alec Jeffreys
(d)
Francois Jacob and Jacques Monod :
NEET 2018
Pisum sativum
TMV
:
:
:
Streptococcus
pneumoniae
Lac operon
149 Number of regulatory and structural genes present in
(a)
(b)
(c)
(d)
galactosidase
α-galactosidase
β-galactosidase
γ-galactosidase
154 Lactose is transported into cells through
(a)
(b)
(c)
(d)
β-galactosidase
permease
transacetylase
transferase
155 The given diagram of the lac operon showing an
operon of inducible enzymes. Identify components
and enzymes (A, B, C, D and E).
lac operon are
(a) one and two
(c) one and one
(a) A–Regulatory gene, B–Promoter, C–Operator,
D–Structural gene
(b) A–Regulatory gene, B–Promoter, C–Structural gene,
D–Operator
(c) A–Regulatory gene, B–Structural gene, C–Pormoter,
D–Operator
(d) A–Regulatory gene, B–Structural gene, C–Operator
gene, D–Promoter gene
(b) one and three
(d) three and one
i
p
o
z
y
a
150 Gene regulation governing lactose operon of E. coli
that involves the lac i gene products is
Transcription
lac mRNA
mRNA
CBSE-AIPMT 2015
(a) positive and inducible because it can be induced by
lactose
(b) negative and inducible because its repressor protein
prevents transcription
(c) negative and repressible because its repressor protein
prevents transcription
(d) feedback inhibition because excess of β-galactosidase
can switch off transcription
151 Which enzyme(s) will be produced in a cell in which
there is a non-sense mutation in the lac y-gene?
(a) β-galactosidase
(b) Lactose permease
(c) Transacetylase
(d) Lactose permease and transacetylase
NEET 2013
i
mRNA
p
C
(a) Operator
(c) Promoter
JIPMER 2018
(b) Inducer
(d) Structural gene
157 Why glucose and galactose cannot act as an inducer
C
o
B
(a) A–Galactosidase, B–Permease, C–Transacetylase,
D–Repressor protein, E–Inducer (lactose)
(b) A–Galactosidase, B–Permease, C–Transacetylase,
D–Inducer (lactose), E–Repressor protein
(c) A–Galactosidase, B–Transacetylase, C–Permease,
D–Repressor protein, E–Inducer (lactose)
(d) A–Permease, B–Transacetylase, C–-Galactosidase,
D–Repressor protein, E–Inducer (lactose)
attached?
operon.
B
A
E
156 To, which of the following, repressor protein is
152 Identify A, B, C and D in the given diagram of a lac
A
Translation
Enzymes
D
for lac operon?
z
y
Repressor
RNA
polymerase operator D
compound
a
(a)
(b)
(c)
(d)
Because they cannot bind with the repressor
Because they can bind with the repressor
Because they can bind with the operator
Because they can bind with the regulator
Repressor
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TOPIC 8 ~ Human Genome Project
158 Which of the following option is true for Human
Genome Project (HGP)?
(a) It was launched in the year 1990 and was called mega
project
(b) Total estimated cost of the project would be 9 billion
US dollars
(c) It aims to identify all 20000-25000 genes in human
DNA
(d) All of the above
159 Human genome project was co-ordinated by
(a)
(b)
(c)
(d)
Europian Department of Energy
US Department of Energy
National Institute of Health
Both (b) and (c)
160 Identify the incorrect option regarding human genome
project.
(a) It was completed in 2003
(b) It aims to determine the sequence of 3 billion chemical
base pairs and store it in data bases
(c) It associated ethical legal and social issues arising from
the project
(d) It is not associated with non-human organisms DNA
sequences
161 Gene library or DNA library has the collection of
(a) DNA and RNA
(b) Any one type of gene of organism
(c) cDNA
(d) All possible genes are organisms
AIIMS 2019
162 Which among the following are non-human model
whose genome are sequenced?
(a) Caenorhabditis elegans
(c) Plants (rice and Arabidopsis)
(b) Drosophila
(d) All of these
163 Identify the incorrect pair.
(a) Expressed sequence tags — Genes that are express as
RNA
— Sequencing genome with
(b) Sequence annotation
coding sequences
(c) Automated DNA sequences — Work on the principle
developed by Frederick
Sanger
(d) None of the above
164 How genetic and physical maps were generated in
HGP?
(a)
(b)
(c)
(d)
By using DNase
By using RNase
By using restriction endonuclease
By using automated DNA sequences
165 To make chromosomal studies easier, chromosomes
are classified into certain groups. So, the chromosome
JIPMER 2019
number 21, 22 and Y are listed in
(a) A
(b) D
(c) E
(d) G
166 Exact number of nucleotides contained in human
genome, revealed by human genome project are
(a) 3164.7 million bp
(c) 3162.7 million bp
(b) 3163.7 million bp
(d) 3160.7 million bp
167 Average gene consists of ...A... bases, but their size
vary greatly, with the largest known human gene
being ...B... with ...C... bases.
Complete the statement filling the correct option in
the given blanks.
(a)
(b)
(c)
(d)
A–3000 bases, B–dystrophin, C–2.4 million
A–2000 bases, B–dystrophin, C–2.4 million
A–1000 bases, B–dystrophin, C–2.0 million
A–3000 bases, B–dystrophin, C–2.0 million
168 Percentage of similarity between the nucleotides of
two individuals is
(a) 98%
(b) 99%
(c) 99.9%
(d) 99.8%
169 Total percentage of genes, which codes for proteins is
(a) 2%
(b) 3%
(c) 4%
(d) 5%
170 Repetitive DNA make up very large portion of human
genome and are important for studying
(a) chromosome structure (b) chromosome dynamics
(d) All of these
(c) evolution
171 Choose the incorrect option.
(a) HGP is closely associated with bioinformatics
(b) HGP will help in developing new ways to diagnose,
treat and some day prevent disorders affecting humans
(c) Fragment sequenced during HGP are done by method
developed by Frederick Sanger
(d) Repetitive DNA sequences are stretches of DNA
repeated 2-3 times in a DNA sequence
172 SNP–Single Nucleotide Polymorphisms is
(a) location on RNA where the single base differs
(b) location on proteins where the single base differs
(c) location on genome where the single base of DNA
differs
(d) location on genome where many bases of DNA differs
173 SNPs can be used for
(a) finding chromosome locations for disease associated
sequences
(b) tracing human history
(c) evolution
(d) All of the above
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CHAPTER 06 > Molecular Basis of Inheritance
TOPIC 9 ~ DNA Fingerprinting
174 DNA fingerprinting involves identifying the
differences in some specific regions in DNA sequence
called
(a)
(b)
(c)
(d)
non-repetitive DNA
coding DNA
non-coding DNA
repetitive DNA
(b) non-satellite DNA
(d) intronic DNA
176 Satellite DNA is important because it
CBSE-AIPMT 2015
(a) codes for proteins needed in cell cycle
(b) shows high degree of polymorphism in population and
also the same degree of polymorphism in an individual,
which is heritable from parents to children
(c) does not code for proteins and is same in all members of
the population
(d) codes for enzymes needed for DNA replication
177 Basis of DNA fingerprinting
high degree of polymorphism in sequences
low degree of polymorphism in sequences
intermediate degree of polymorphism in sequences
sequences show no polymorphism
178 The technique of DNA fingerprinting was initially
developed by
(a) Lalji Singh
(c) Frederick Sanger
(b) Alec Jeffreys
(d) Jacob and Monod
179 Alec Jeffreys used a satellite DNA as probe that
shows very high degree of polymorphism. It was
called as
(a)
(b)
(c)
(d)
Short Number of Tandem Repeats (SNTRs)
Large Number of Tandem Repeats (LNTRs)
Variable Number of Tandem Repeats (VNTRs)
All of the above
180 VNTR belongs to the class of satellite DNA referred
to as
(a)
(b)
(c)
(d)
microsatellite DNA
minisatellite DNA
megasatellite DNA
repetitive DNA
(b) 0.2-10 kb
(d) 0.4-15 kb
increased by
major peaks during density gradient centrifugation.
The other small peaks are referred to as
(a)
(b)
(c)
(d)
(a) 0.1-20 kb
(c) 0.3-30 kb
182 The sensitivity of DNA fingerprinting can be
175 The bulk of DNA (other than repetitive) forms the
(a) satellite DNA
(c) exonic DNA
181 VNTR varies in size from
(a)
(b)
(c)
(d)
using intron sequences
using exon sequences
using polymerase chain reactions
All of the above
183 Southern blotting technique involves the transfer of
DNA from
(a)
(b)
(c)
(d)
gel to membrane
membrane to gel
solution to gel
gel to solution
184 Steps in DNA fingerprinting are
Isolation of DNA
↓
Digestion of DNA by (A)
↓
Separation of DNA by (B)
↓
Transfering of DNA to (C)
↓
DNA hybridisation using (D)
↓
Detecting of hybridised DNA by (E)
Complete the accompanying A, B, C, D and E in the
flowchart are
(a) A–Restriction endonuclease, B–Electrophoresis,
C–Nitrocellulose or nylon, D–Labelled VNTR probe,
E–Autoradiography
(b) A–Electrophoresis, B–Restriction endonuclease,
C–Nitrocellulose or nylon, D–Labelled VNTR probe,
E–Autoradiography
(c) A–Restriction endonuclease, B–Electrophoresis,
C–Labelled VNTR probe, D–Nitrocellulose or nylon,
E–Autoradiography
(d) A–Restriction endonuclease, B–Electrophoresis,
C–Nitrocellulose or nylon, D–Autoradiography,
E–Labelled VNTR probe
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NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
■ Directions (Q. No. 185-199) In each of the following
questions, a statement of Assertion (A) is given by
corresponding statement of Reason (R). Of the
statements, mark the correct answer as
(a) If both A and R are true and R is the correct explanation
of A
(b) If both A and R are true, but R is not the correct
explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true
193 Assertion (A) hnRNA is larger than mRNA.
194
195
185 Assertion (A) DNA acts as a genetic material in all
organisms.
Reason (R) It is a double-stranded biomolecule in
most organisms.
196
186 Assertion (A) DNA has two chains having
antiparallel polarity.
Reason (R) In one chain of DNA at one end has a
free phosphate moiety 5′ end of ribose sugar and at
other end the ribose has a free 3′ OH group.
197
198
187 Assertion (A) Adenine cannot pair with cytosine.
Reason (R) Adenine and cytosine do not have
complementarity between their respective hydrogen
donor and hydrogen acceptor sites.
188 Assertion (A) Histones are basic in nature.
Reason (R) These are rich in the amino acids lysine
and arginine.
199
Reason (R) hnRNA has non-coding introns which are
not required for translation.
Assertion (A) Polycistronic mRNA is capable of
forming a number of different polypeptide chains.
Reason (R) Polycistronic mRNA has terminator
codons.
Assertion (A) In transcription, the strand with 3′ → 5′
polarity acts as the template strand.
Reason (R) The enzyme RNA polymerase catalyses
the polymerisation in only one direction, i.e. 5′ → 3′.
Assertion (A) In eukaryotes, transcription occurs in
nucleus.
AIIMS 2019
Reason (R) In bacteria, transcription and translation
occur in cytoplasm.
Assertion (A) The genetic code is degenerate.
Reason (R) Most amino acids are coded by more than
one codon.
Assertion (A) mRNA has some untranslated regions
that are not translated.
Reason (R) UTRs are required for efficient
translation.
Assertion (A) DNA fingerprinting is very
well-known for its application in paternity testing in
case of disputes.
Reason (R) It employs the principle of DNA
polymorphism.
189 Assertion (A) Heterochromatin is transcriptionally
inactive.
Reason (R) It is densely packed.
190 Assertion (A) Viruses having RNA genome and
shorter lifespan, mutate and evolve faster.
Reason (R) RNA is unstable and thus mutates faster.
191 Assertion (A) Replication on one strand of DNA is
continuous and on another it is discontinuous.
Reason (R) The DNA polymerase works in 3′ → 5′
direction.
192 Assertion (A) Replication and transcription occur in
the nucleus, but translation takes place in the
cytoplasm.
Reason (R) mRNA is transferred from the nucleus
into cytoplasm where ribosomes and amino acids are
available for protein synthesis.
II. Statement Based Questions
200 Read the following statements.
I. A purine is heterocyclic, 9-membered double ring
structure with nitrogen at 1st, 3rd, 7th and 9th positions.
II. A pyrimidine is heterocyclic, 6-membered single ring
structure with nitrogen at 1st and 3rd positions.
III. Purine nucleosides have1′-9 glycosidic linkage
whereas pyrimidine nucleosides have1′-1-glycosidic
linkage.
IV. Two nucleosides are linked by 3′-5′ phosphodiester
linkage to form a dinucleotide.
V. Ribose sugar can be represented as C5 H10 O4 whereas
deoxyribose sugar can be represented as C5 H10 O5 .
Which of the above statement(s) is/are correct?
(a) Only I
(c) III, IV and V
(b) I, II, III and IV
(d) IV and V
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CHAPTER 06 > Molecular Basis of Inheritance
201 Choose the incorrect statement.
(a) A nucleotide contains ribose sugar or deoxyribose sugar
(b) A nucleotide contains pyrimidine bases and purine
bases
(c) A nucleotide contains protein, carbohydrates and fats
(d) A phosphate group is present in a nucleotide
202 Which of the following statements about Griffith’s
experiment are correct?
I. S-strain have mucus (polysaccharide) coat.
II. S-strain are virulent is cause pneumonia infection,
while R-strain do not.
III. Transforming principle is associated with genetic
material of R-strain.
IV. Transformation of R-strain into S-strain can take place
in a test tube.
(a) I and III
(c) I, II and IV
(b) III and IV
(d) II, III and IV
203 Choose the correct statements about biochemical
characterisation of transforming principle in Griffith’s
experiment.
I. It was done by Oswald Avery, Colin MacLeod and
Maclyn McCarty.
II. Scientists purified biochemicals (proteins, DNA,
RNA, etc.) from heat killed S-cell.
III. It was seen that DNA alone from S-bacteria caused
R-bacteria to become transformed .
IV. Proteases and RNases did not affect transformation.
(a)
(b)
(c)
(d)
I and II
III and IV
I and III
All statements are correct
204 Which of the following statements about Hershey and
Chase experiment are correct?
I. Sulphur is present in proteins, but not in DNA.
II. Phosphorus is present in DNA, but not in proteins.
III. 32P will end up in the supernatant after centrifugation.
IV. Progeny generation of T 2 -bacteriophage contains 32P.
(a) I and II
(c) III and IV
(b) II and III
(d) I, II and IV
205 Choose the incorrect statement(s) about the
experiment conduted by Meselson and Stahl’s that
(a) equal amount of light DNA and hybrid DNA was
observed in E. coli culture after two generations
(b) the generation time of E. coli culture was 40 minutes
(c) the equal amount of light DNA and hybrid DNA was
observed in E. coli culture after three generations
(d) Both (a) and (b)
206 J Watson and F Crick proposed the double helix
model of DNA. Choose the correct statements with
respect to their model of DNA.
I. Based on X-ray diffraction of DNA produced by
M Wilkins and R Franklin.
II. One of the hall marks of their proposition was base
pairing between the two strands of polynucleotide
chains.
III. The two polynucleotide chains are antiparallel to each
other .
IV. Based on Chargaff’s rule(A + G / T + C = 1)
Choose the correct option.
(a)
(b)
(c)
(d)
I, II and III
II, III and IV
I, II, III and IV
All of the above
207 Choose the incorrect statement about the
semiconservative scheme of DNA replication.
(a) Watson and Crick proposed the scheme for replication
of DNA in 1953
(b) The scheme suggested that the two strands would
separate and act as a template for the synthesis of new
complementary strands
(c) Griffith proposed the scheme of semiconservative DNA
replication
(d) After the completion of replication, each DNA
molecule would have one parental and one newly
synthesised strand
208 Arrange the following events of replication of DNA.
I. Bonds between complementary bases breaks.
II. Bonds between complementary bases forms.
III. DNA molecules uncoils.
IV. Opposite strands separates.
V. Sugar phosphate bonds forms.
VI. Free nucleotides align with the complementary
nucleotides on each strand.
Choose the correct option.
(a)
(b)
(c)
(d)
VI → I → III → IV → V → II
III → VI → I → IV → V → II
I → III → VI → IV → II → V
III → I → IV → VI → II → V
209 Choose the correct statements about DNA replication.
I. Discontinuously synthesised fragments are later
joined by the enzyme DNA ligase.
II. There is a definite region in E. coli DNA where the
replication originates, known as origin of replication.
III. In eukaryotes, the replication of DNA takes place at
S-phase of the cell cycle.
IV. Failure of cell division after DNA replication results in
polyploidy.
V. E. coli having 4.6 × 106 bp completes DNA replication
within 38 minutes.
(a) I and II
(c) I and V
(b) III and IV
(d) All of these
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210 Choose the correct statement.
(a) The regions of transcriptional units are promoter,
structural gene and terminator
(b) The region of transcriptional units are exon, intron and
cistron
(c) The region of DNA where transcription stops is present
on promoter
(d) The terminator codes for enzyme or protein
211 Consider the following statements.
I. The presence of a promoter in a transcription unit
defines the template and coding strands.
II. DNA-dependent RNA polymerase catalyse the
polymerisation in only one direction that is 5′→3′.
III. The DNA sequence coding for tRNA or rRNA
molecules also define a gene.
IV. Regulatory sequences are loosely defined as
regulatory genes and these sequences do not code for
any RNA or protein.
Choose the correct statements.
(a) I and IV
(c) II and IV
(b) I, II and III
(d) I, II, III and IV
212 Which one of the following statement is incorrect?
(a) Structural gene in transcription unit is monocistronic in
eukaryotes and polycistronic in bacteria
(b) Monocistronic genes in eukaryotes are split
(c) Exons are non-coding and introns are coding sequences
of gene
(d) Intervening sequences do not appear in mature or
processed RNA
213 Choose the correct statement(s).
(a) The factors required for the synthesis of protein are
initiation code and ribosomes
(b) The factors required for the synthesis of protein are
GTP, ATP and amino acid pool
(c) The factors required for the synthesis of protein are
tRNA and mRNA
(d) All of the above
214 Consider the following statements.
I. rRNA provides the template for synthesis of proteins.
II. tRNA brings amino acids and reads the genetic code.
III. RNA polymerase binds to promoter and initiates
transcription.
IV. A segment of DNA coding for polypeptide is called
intron.
Which of the statements given above are correct?
(a) I and III (b) I and II (c) I, II and III (d) II and III
215 Following are the stages in the cellular synthesis of a
protein.
I. Movement of mRNA from the nucleus to cytoplasm.
II. Linking of adjacent amino acid molecules.
III. Transcription of mRNA from a DNA template.
IV. Formation of the polypeptide chain.
V. Attachment of the mRNA strand to a ribosome.
In which order do these stages take place?
(a) III I
(b) I III
(c) I V
(d) III IV
V
II
III
I
II
V
IV
II
IV
IV
II
V
216 The difference(s) between mRNA and tRNA is/are
that
I. mRNA has more elaborated 3-dimensional structure
due to extensive base pairing.
II. tRNA has more elaborated 3-dimensional structure
due to extensive pairing.
III. tRNA is usually smaller than mRNA.
IV. mRNA contains anticodons, but tRNA contains
codons.
Choose the correct statements.
(a) I, II, III and IV
(c) I and III
(b) II and III
(d) I, II and III
217 Few steps involved in polypeptide synthesis are given
below. In which of the following steps does tRNA
participates?
I. Activation of amino acids by binding with aminoacyl
tRNA synthetase enzyme.
II. Elongation of polypeptide chain.
III. Translation of mRNA to form a polypeptide.
IV. Transcription of DNA into RNA.
(a) I, III and IV
(c) I, II and IV
(b) II, III and IV
(d) I, II and III
218 Select the correct statements out of the four (I-IV)
given below about lac operon.
I. Glucose or galactose may bind with the repressor and
inactivate it.
II. In the absence of lactose, the repressor binds with the
operator region.
III. Tryptophan acts as an inducer for the gene expression.
IV. Regulatory gene is the one that produces the repressor
molecule.
Choose the correct option.
(a) II and III (b) I and III (c) II and IV
(d) I and II
219 Which of the following statements concerning the
regulatory genes (R), associated with the lac operon
are incorrect?
I. mRNA is transcribed from the R gene whether lactose
is present or not.
II. mRNA is transcribed from the R gene only when the
lactose is present.
III. mRNA is transcribed from the R gene only when the
lactose is not present.
IV. Lactose inhibits the translation of R gene mRNA.
(a) I and II
(c) III and IV
(b) II and III
(d) II, III and IV
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CHAPTER 06 > Molecular Basis of Inheritance
220 Identify the incorrect statement for lac operon model.
(a) Lactose acts as inducer which inactivates repressor
(b) RNA polymerase stay away from promoter in the
presence of repressor
(c) Regulation of lac operon by repressor is referred to as
negative regulation
(d) The repressor of the operon is synthesised during
specific periods from r-gene
221 Select the incorrect statement from the following.
AIIMS 2019
(a) The human genome contains 3164.7 million nucleotide
bases
(b) Less than 10% of the genome codes for proteins
(c) Repeated sequences make up very large portion of the
human genome
(d) Chromosome 1 has most genes (2968) and Y has the
fewest (231)
222 Consider the following statements.
I. Major countries who contributed or participated in
human genome project were Japan, France, Germany
and China.
II. Human genome project was a mega project of 13 years.
Choose the correct option.
(a) Statement I is true, but II is false
(b) Statement II is true, but I is false
(c) Both statement I and II are correct
(d) Both statement I and II are incorrect
225 Tandem Repeat DNA
I. is classified as microsatellites and minisatellites.
II. normally does not code for any protein.
III. shows polymorphism.
IV. is used in fingerprinting.
Choose the correct option to complete the statement.
(a) I and III
(c) I, III and IV
III. Matching Type Questions
226 Match the following columns.
Column I
(Scientists)
1.
DNA double helix
B.
Griffith
2.
Nuclein
C.
Hershey and Chase
3.
Streptococcus pneumoniae
D. Watson and Crick
4.
Bacteriophage
E.
5.
X-ray diffraction studies
are
I. isolation of total DNA.
II. cloning in suitable vectors.
III. sequence arrangment by computer.
IV. formation of physical and genetic maps.
V. converting the fragments.
VI. using automated sequencer.
VII. using restriction endonuclease recognition sites.
VIII. completition of human genome sequencing.
Choose the correct option in which the above given
steps are arranged properly.
(a)
(b)
(c)
(d)
I, II, III, IV, V, VI, VII, VIII
I, V, II, VI, III, VII, IV, VIII
I, II, V, VI, III, IV, VIII, VII
I, II, V, VI, III, VII, VIII, IV
Wilkins and Franklin
Codes
A
(a) 5
(b) 1
(c) 2
(d) 1
B
4
4
3
3
C
3
3
4
4
D
1
2
1
2
E
2
5
5
5
227 Match the following columns.
Column I
(Features)
Project (HGP).
224 Steps in sequencing Human Genome Project (HGP)
Column II
(Discoveries)
A. F Miescher
223 Choose the incorrect statement about Human Genome
(a) Commonly used host for cloning in HGP were PAC
(Plasmic Artificial Chromosome) and GMO
(Genetically Modified Organisms)
(b) The alignment of sequences obtained was done by
computer based programs
(c) The developed sequences were annotated and were
assigned to each chromosome
(d) The human genome has 22 autosomes, X and Y
(b) I, II and III
(d) I, II, III and IV
Column II
(Associated enzymes)
A.
RNA digesting enzymes
1. Lipase
B.
Protein digesting enzymes
2. DNase
C.
DNA digesting enzymes
3. Protease
D.
Fat digesting enzymes
4. RNase
Codes
A
(a) 3
(c) 4
B
4
3
C
2
2
D
1
1
A
(b) 1
(d) 1
B
2
2
C
4
3
D
3
4
228 Match the following columns.
Column I
(Enzymes)
Column II
(Functions)
A. Topoisomerase 1. Relaxes the DNA from its
super-coiled nature.
B. DNA gyrase
2. Relieves strain of unwinding by DNA
helicase; this is a specific type of
topoisomerase.
C. DNA ligase
3. Re-anneals the semiconservative
strands and joins okazaki fragments
of the lagging strand.
D. Telomerase
4. Provides a starting point of RNA
(or DNA) for DNA polymerase to
begin synthesis of the new DNA
strand.
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Master The NCERT > BIOLOGY (Vol-II)
148
Codes
A
(a) 1
(c) 2
232 Match the following columns.
B
2
4
C
4
3
D
3
1
A
(b) 1
(d) 1
B
2
3
C
3
2
D
4
4
229 Match the following columns.
Column I
Column II
A. Splicing
1.
Lac operon
B.
Okazaki fragment
2.
Lagging strand
C.
Jacob and Monod
3.
Lactose
4.
Removal of introns
D. Inducer
Codes
A
(a) 1
(c) 4
B
2
2
C
3
3
D
4
1
A
(b) 4
(d) 2
B
2
4
C
1
3
D
3
1
230 Match the given enzymes with their respective
function in DNA replication.
Column I
Column II
A. DNA helicase
1.
B. DNA
polymerase
2.
C. DNA clamp
3.
D. Single-Strand
Binding (SSB)
Proteins
Codes
A
(a) 1
(c) 4
B
2
3
C
4
2
4.
D
3
1
A protein which prevents DNA
polymerase-III form dissociating
from the DNA parent strand.
Bind to ssDNA and prevent the
DNA double helix from
re-annealing after DNA helicase
unwinds it thus maintaining the
strand separation.
Also known as helix destabilising
enzyme and unwinds the DNA
double helix at the replication fork.
Build a new duplex DNA strand by
adding nucleotides in the 5′ to 3′
direction. Also performs
proofreading and error correction.
A
(b) 3
(d) 1
B
4
2
C
1
3
D
2
4
231 Match the following columns.
Column I
Column II
A.
Sigma factor
1.
5′−3′
B.
Capping
2.
Initiation
C.
Tailing
3.
5′ end
D.
Coding strand
4.
3′ end
Codes
A
(a) 4
(c) 1
B
1
3
C
2
4
D
3
2
A
(b) 2
(d) 3
B
4
2
Column I
Column II
A. tRNA
1. Linking of amino acids
B. mRNA
2. Transfer of genetic information
C. rRNA
3. Nucleolar organising region
D. Peptidyl transferase
4. Transfer of amino acid from
cytoplasm to ribosome
Codes
A
(a) 4
(b) 1
(c) 1
(d) 1
B
2
4
2
3
C
3
3
3
2
D
1
2
4
4
233 Match the following columns.
Column I
Column II
A. Exon
1.
Coding sequence
B. Intron
2.
Non-coding sequence
C. Genetic code
3.
Triplet bases on mRNA
D. DNA packaging
4.
Nucleosome
Codes
A
(a) 1
(c) 1
B
3
2
C
2
3
D
4
4
A
(b) 1
(d) 4
B
4
1
C
2
2
D
3
3
234 Match the following columns.
Column I
Column II
A. 5′–AUG–3′
1.
Segment of DNA
B. RNA with introns and exon
2.
Chromatin
C. Gene
3.
hnRNA
D. Nucleosomes
4.
Initiation codon
Codes
A
(a) 4
(c) 2
B
3
1
C
1
4
D
2
3
A
(b) 4
(d) 2
B
2
3
C
1
1
D
3
4
235 Match the following columns.
Column I
(Functions)
C
3
1
D
1
4
Column II
(Segments of DNA)
A. Segment of DNA coding for
polypeptide
1.
Recon
B. Segment of DNA goes for
recombination
2.
Muton
C. Segment of DNA goes for
mutation
3.
Cistron
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CHAPTER 06 > Molecular Basis of Inheritance
Codes
A
(a) 1
(c) 3
B
2
1
C
3
2
A
(b) 3
(d) 1
B
2
3
C
1
2
236 Match the following RNA polymerases with their
transcribed products.
NEET (Odisha) 2019
A.
RNA polymerase-I
1. t RNA
B.
RNA polymerase-II
2. rRNA
C.
RNA polymerase-III
3. hnRNA
Codes
A
(a) 1
(c) 2
B
3
3
C
2
1
A
(b) 1
(d) 3
B
2
2
C
3
1
their respective products.
NEET 2019
Column II
i gene
1. β-galactosidase
B.
z gene
2. Permease
C.
a gene
3. Repressor
D.
y gene
4. Transacetylase
A.
Codes
A
(a) 1
(c) 3
C
3
1
1
2
D
4
2
4
1
Column I
237 Match the following genes of the lac operon with
Column I
B
2
4
2
1
239 Match the following columns.
Column II
Column I
Codes
A
(a) 1
(b) 3
(c) 3
(d) 4
Column II
A. Termination (Translation)
1. Aminoacyl tRNA
synthatase
B. Translation
2. Okazaki fragments
C. Transcription
3.
D. DNA replication
4. RNA polymerase
Codes
A
(a) 3
(b) 2
(c) 4
(d) 2
B
1
3
3
1
C
4
1
1
3
D
2
4
2
4
240 Identify the correct match between the codons and
coding functions.
Column I
B
2
4
C
3
1
D
4
2
A
(b) 3
(d) 1
B
1
3
C
4
2
D
2
4
238 Match the following columns.
Column I
(Enzymes)
Column II
(Functions)
A. β-galactosidase
1. Joining of DNA fragments
B. Permease
2. Peptide bond formation
GTP dependent release
factor
C. Ligase
3. Hydrolysis of lactose
D. Ribozyme
4. Increase permeability to β-lactose
Column II
A. AUG
1. Phenylalanine
B.
UAA
2. Methionine
C.
UUU
3. Tryptophan
D. UGG
4. Termination
Codes
A
(a) 1
(b) 2
(c) 4
(d) 4
B
4
4
3
1
C
2
1
2
3
D
3
3
1
2
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150
NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
241 In a DNA strand the nucleotides are linked together by
(a) glycosidic bonds
(c) peptide bonds
(b) phosphodiester bonds
(d) hydrogen bonds
242 A nucleoside differs from a nucleotide. It lacks the
(a) base
(c) phosphate group
(b) sugar
(d) hydroxyl group
243 Both deoxyribose and ribose belong to a class of
sugars called
(a) trioses
(c) pentoses
244 The fact that a purine always paired base through
hydrogen bonds with a pyrimidine base leads to, in
the DNA double helix
(a) the antiparallel nature
(b) the semiconservative nature
(c) uniform width throughout DNA
(d) uniform length in all DNA
245 Which of the following are the functions of RNA?
(a) It is carrier of genetic information from DNA to
ribosomes synthesising polypeptides
(b) It carries amino acids to ribosomes
(c) It is a constituent component of ribosomes
(d) All of the above
246 Who amongst the following scientists had no
contribution in the development of the double helix
model for the structure of DNA?
(b) Maurice Wilkins
(d) Meselson and Stahl
247 While analysing the DNA of an organism a total
number of 5386 nucleotides were found out of which
the proportion of different bases were Adenine =
29%, Guanine = 17%, Cytosine = 32%, Thymine =
17%. Considering the Chargaff’s rule it can be
concluded that
(a) it is a double-stranded circular DNA
(b) it is single-stranded DNA
(c) it is a double-stranded linear DNA
(d) No conclusion can be drawn
248 In some viruses, DNA is synthesised by using RNA
as template. Such a DNA is called
(a) A-DNA
(a) protein
(c) DNA
(b) B-DNA (c) cDNA
(d) rDNA
249 The net electric charge on DNA and histones is
(a) positive
(b) negative
(c) negative and positive, respectively
(d) zero
(b) carbohydrates
(d) RNA
251 If Meselson and Stahl’s experiment is continued for
four generations in bacteria, the ratio of
15
N / 15 N : 15 N / 14 N : 14 N / 14 N containing DNA in
the fourth generation would be
(a) 1:1:0
(b) hexoses
(d) polysaccharides
(a) Rosalind Franklin
(c) Erwin Chargaff
250 The first genetic material could be
(b) 1:4:0
(c) 0:1:3
(d) 0:1:7
252 DNA is a polymer of nucleotides which are linked to
each other by 3′–5′ phosphodiester bond. To prevent
polymerisation of nucleotides, which of the
following modifications would you choose?
(a) Replace purine with pyrimidines
(b) Remove/Replace 3′ OH group in deoxyribose
(c) Remove/Replace 2′ OH group with some other group in
deoxyribose
(d) Both (b) and (c)
253 Discontinuous synthesis of DNA occurs in one strand,
because
(a) DNA molecule being synthesised is very long
(b) DNA-dependent DNA polymerase catalyses
polymerisation only in one direction (5′ → 3′)
(c) it is a more efficient process
(d) DNA ligase has to have a role
254 If the sequence of nitrogen bases of the coding strand
of DNA in a transcription unit is
5' – A T G A A T G – 3',
the sequence of bases in its RNA transcript would be
(a) 5′ – A U G A A U G – 3′ (b) 5′ – U A C U U A C – 3′
(c) 5′ – C A U U C A U – 3′ (d) 5′ – G U A A G U A – 3′
255 The promoter site and the terminator site for
transcription are located at
(a) 3′ (downstream) end and 5′ (upstream) end, respectively
of the transcription unit
(b) 5′ (upstream) end and 3′ (downstream) end, respectively
of the transcription unit
(c) the 5′ (upstream) end
(d) the 3′ (downstream) end
256 The RNA polymerase holoenzyme transcribes
(a) the promoter, structural gene and the terminator region
(b) the promoter and the terminator region
(c) the structural gene and the terminator regions
(d) the structural gene only
257 Which one of the following steps in transcription is
catalysed by RNA polymerase?
(a) Initiation
(c) Termination
(b) Elongation
(d) All of these
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CHAPTER 06 > Molecular Basis of Inheritance
258 Which one of the following is true with respect to AUG?
(a) lactose is present and it binds to the repressor
(b) repressor binds to operator
(c) RNA polymerase binds to the operator
(d) lactose is present and it binds to RNA polymerase
(a) exons and introns do not appear in the mature RNA
(b) exons appear, but introns do not appear in the mature
RNA
(c) introns appear, but exons do not appear in the mature
RNA
(d) Both exons and introns appear in the mature RNA
265 Regulatory proteins are the accessory proteins that
interact with RNA polymerase and affect its role in
transcription. Which of the following statements is
correct about regulatory protein?
(a) They only increase expression
(b) They only decrease expression
(c) They interact with RNA polymerase, but do not
affect the expression
(d) They can act both as activators and as repressors
260 To initiate translation, the mRNA first binds to
(a) the smaller ribosomal subunit
(b) the larger ribosomal subunit
(c) the whole ribosome
(d) No such specificity exists
266 Which was the last human chromosome to be
261 If the base sequence of a codon in mRNA is 5'–AUG–3',
the sequence of tRNA pairing with it must be
completely sequenced?
(a) Chromosome 1
(c) Chromosome 21
(b) 5′ – CAU – 3′
(d) 5′ – GUA – 3′
(b) Chromosome 11
(d) Chromosome-X
267 The human chromosome with the highest and least
262 The amino acid attaches to the tRNA at its
(a) 5′-end
(c) Anticodon site
(b) transcription
(d) None of these
264 In E. coli, the lac operon gets switched on when
259 With regard to mature mRNA in eukaryotes
(a) 5′ – UAC – 3′
(c) 5′ – AUG – 3′
263 Control of gene expression takes place at the level of
(a) DNA-replication
(c) translation
(a) It codes for methionine only
(b) It is also an initiation codon
(c) It codes for methionine in both prokaryotes and
eukaryotes
(d) All of the above
number of genes in them are respectively
(b) 3′-end
(d) DHU loop
(a) chromosome 21 and Y (b) chromosome 1 and X
(c) chromosome 1 and Y (d) chromosome X and Y
Answers
> Mastering NCERT with MCQs
1 (a)
16 (c)
31 (a)
46 (b)
61 (b)
76 (c)
91 (c)
106 (a)
121 (c)
136 (a)
151 (a)
166 (a)
181 (a)
2 (b)
17 (c)
32 (a)
47 (a)
62 (b)
77 (a)
92 (a)
107 (c)
122 (c)
137 (c)
152 (a)
167 (a)
182 (c)
3 (d)
18 (d)
33 (c)
48 (b)
63 (a)
78 (c)
93 (d)
108 (a)
123 (c)
138 (d)
153 (c)
168 (c)
183 (a)
4 (a)
19 (c)
34 (d)
49 (a)
64 (c)
79 (a)
94 (c)
109 (b)
124 (c)
139 (c)
154 (b)
169 (a)
184 (a)
5 (c)
20 (c)
35 (c)
50 (d)
65 (b)
80 (b)
95 (c)
110 (b)
125 (a)
140 (b)
155 (a)
170 (d)
6 (a)
21 (c)
36 (b)
51 (d)
66 (a)
81 (b)
96 (b)
111 (c)
126 (a)
141 (c)
156 (a)
171 (d)
7 (a)
22 (c)
37 (c)
52 (b)
67 (c)
82 (c)
97 (a)
112 (d)
127 (c)
142 (d)
157 (a)
172 (c)
8 (a)
23 (c)
38 (a)
53 (c)
68 (d)
83 (d)
98 (c)
113 (d)
128 (c)
143 (b)
158 (d)
173 (d)
9 (b)
24 (a)
39 (a)
54 (a)
69 (b)
84 (a)
99 (d)
114 (b)
129 (a)
144 (a)
159 (d)
174 (d)
10 (b)
25 (c)
40 (a)
55 (c)
70 (a)
85 (a)
100 (d)
115 (a)
130 (b)
145 (c)
160 (d)
175 (a)
11 (a)
26 (a)
41 (b)
56 (a)
71 (a)
86 (a)
101 (b)
116 (a)
131 (a)
146 (b)
161 (c)
176 (b)
12 (c)
27 (d)
42 (d)
57 (b)
72 (d)
87 (b)
102 (b)
117 (c)
132 (c)
147 (b)
162 (d)
177 (a)
13 (d)
28 (a)
43 (d)
58 (a)
73 (a)
88 (*)
103 (a)
118 (c)
133 (d)
148 (d)
163 (b)
178 (b)
14 (d)
29 (b)
44 (c)
59 (c)
74 (b)
89 (c)
104 (b)
119 (a)
134 (c)
149 (b)
164 (c)
179 (c)
15 (b)
30 (c)
45 (b)
60 (a)
75 (a)
90 (c)
105 (c)
120 (a)
135 (c)
150 (b)
165 (d)
180 (b)
190 (a)
205 (c)
220 (d)
235 (c)
191 (a)
206 (d)
221 (b)
236 (c)
192 (a)
207 (c)
222 (c)
237 (b)
193 (a)
208 (d)
223 (a)
238 (b)
194 (b)
209 (d)
224 (b)
239 (a)
195 (a) 196 (b) 197 (a) 198 (b) 199 (a)
210 (a) 211 (d) 212 (c) 213 (d) 214 (d)
225 (d) 226 (c) 227 (c) 228 (b) 229 (b)
240 (b)
245 (d) 246 (d) 247 (b) 248 (c)
249 (c)
250 (d) 251 (d) 252 (b) 253 (b) 254 (a) 255 (b)
> NEET Special Types Questions
185 (d)
200 (b)
215 (a)
230 (b)
>
186 (a)
201 (c)
216 (b)
231 (b)
187 (a)
202 (c)
217 (d)
232 (a)
188 (a)
203 (d)
218 (c)
233 (c)
189 (a)
204 (d)
219 (d)
234 (a)
NCERT Exemplar Questions
241 (b) 242 (c)
256 (c)
243 (c)
244 (c)
257 (b) 258 (d) 259 (b) 260 (a) 261 (b) 262 (b) 263 (b,c) 264 (a) 265 (d) 266 (a) 267 (c)
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Answers & Explanations
1 (a) DNA is a long chain of polymer of
2
3
4
7
10
13
16
deoxyribonucleotide in which a phosphate group is
attached to 5′− OH of nucleoside through
phosphodiester linkage.
(b) Length of DNA is directly proportional to the
number of nucleotides. As the number of nucleotides
increases, the length of DNA also increases.
(d) Option (d) is the incorrect match and can be
corrected as
Haploid content of human DNA is 3.3 × 109 bp.
Rest of the matches are correct.
(a) Adenine and guanine are the purines which are
found both in DNA and RNA. Cytosine and thymine are
the pyrimidines which are found in DNA. In case of
RNA, thymine is replaced by uracil.
(a) Adenosine and deoxyadenosine differ in only sugar.
Nitrogenous bases are attached to the pentose sugar by
N-glycoside bond.
If ribose sugar is present then it is called nucleoside and
when deoxyribose sugar is present then it is called
deoxynucleoside, i.e. adenoside (sugar is ribose),
deoxyadenoside (sugar is deoxyribose), cytidine,
deoxycytidine, uridine or deoxythymine.
(b) Adenylic acid, cytidilic acid and guanylic acid are
nucleotides. A nucleotide is composed of three
components – nitrogen base (adenosine, cytosine,
guanine), ribose sugar and a phosphate group. These are
monomer unit of nucleic acid, i.e. RNA and DNA.
Adenine, cytidine, thymidine are nucleosides.
Uracil, cytosine and adenosine are nitrogenous bases.
(d) Thymine and uracil, both have similar structures and
are pyrimidine. Thymine ring has one additional methyl
group at 5′ position in its pyrimidine ring. Therefore it is
also called 5 methyl uracil.
(c) The percentage of bases which are pyrimidines is
50%. According to Chargaff’s rule
A + G = C + T = 50%
(Purines)
Answers & Explanations
∴
(Pyramidines)
If A = 20%, then T = 20%
C + T = 50%
C = 50% − 20% = 30%
Total percentage of pyrimidine bases
(T + C) are 20 + 30 = 50%
17 (c) Chargaff’s rule states that purine and pyrimidine
base pairs are present in equal amount in dsDNA, i.e.
A = T, G = C.
i.e. ( A + T ) = ( G + C )
A+T
=1
∴
G+ C
If cytosine = 17%, then G = 17%
If A + G + C + T = 100 and G = C, A = T
A + 17 + 17 + T = 100
A + T + 34 = 100
A + T = 100 − 34
A + T = 66
A = T = 66 / 2 = 33%
Hence, if cytosine is 17% then G = 17% and A and T
will be 33% each.
20 (c) Option (c) is incorrect and can be corrected as
Adenine forms two hydrogen bonds with thymine of
the opposite strand and vice-versa. On the other hand,
guanine is bounded with cytosine with three H-bonds.
Rest of the options are correct.
23 (c) The length of DNA in a human cell is about 2.2 m.
It can be calculated as
The distance between two consecutive base pairs
= 0.34 nm or 0.34 × 10−9 m
then
If the length of DNA double helix in a typical
mammalian cell
= The total number of bp × Distance between two
consecutive bp
= 6.6 × 109 bp × 0.34 × 10−9 m/bp = 2.2 m
24 (a) In the given case, the number of base pairs for
E. coli would be 4 × 106 bp. It can be calculated as
Average distance between two base pairs of DNA is
3.4 Å. Length of E. coli DNA is = 1.36 × 107 Å
1.36 × 107 Å
= 0.39 × 107
So, number of nucleotides =
3.4Å
~ 4 × 106 bp
= 3.9 × 106 =
26 (a) In a eukaryotic cell, the DNA packaging has
positively charged basic proteins called as histones. A
protein acquires charge depending upon the abundance
of amino acids residues with charged side chains.
Histones are rich in basic amino acid residues lysine
and arginine and hence are positively charged.
27 (d) Option (d) is the incorrect match and can be
corrected as
Chromatin are thread-like stained (coloured) bodies
seen in nucleus. The nucleosomes in chromatin are seen
as ‘beads on string’ when viewed under electron
microscope.
Rest of the matches are correct.
28 (a) Linker-DNA is attached to H1 histone protein.
Linker DNA connects two adjacent nucleosomes. Its
length is varied (about 145 Å with 70 bp). Nucleosome
and linker DNA together constitute chromatosome.
Chromatosome contains a histone octamer and DNA.
29 (b) The packaging of chromatin at higher level requires
an additional set of proteins that are collectively called
non-histone proteins (i.e. H2A and H2B).
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CHAPTER 06 > Molecular Basis of Inheritance
30 (c) The association of H1 histone with nucleosome
35
37
38
58
60
62
63
65
67
44 (c) Option (c) is the incorrect trait and can be
47
49
50
55
56
corrected as
A molecule that can act as a genetic material must be
stable structurally and chemically.
Rest of the options are correct.
(a) Both DNA and RNA are able to mutate. Infact
RNA being unstable, mutates at a faster rate.
Consequently, viruses having RNA genome and shorter
lifespan, mutate and evolve faster.
(a) RNA was the first genetic material. There is now
enough evidence to suggest that the essential life
processes has evolved around RNA.
(d) Chargaff’s rule is not applicable to RNA. It is the
generalised formula about DNA structure. The rule
states that DNA from any cell of an organism should
have a 1 : 1 ratio (base pair rule) of pyrimidine and
purine bases, i.e. the amount of guanine is equal to
cytosine and the amount of adenine is equal to thymine.
(c) Heavy DNA molecule could be distinguished from
the normal DNA by centrifugation in a cesium chloride
(CsCl) density gradient.
(a) In Meselson and Stahl’s experiment, the generation
time (replication time) of E. coli culture is about
68
20 minutes. Therefore, the DNA extracted after the
interval of 20 minutes in the experiment had heavy 15 N
incorporated in its genetic material and had a hybrid
density.
(a) An experiment similar to Meselson and Stahl
experiment was performed on Vicia faba (faba beans)
by Taylor and colleagues in 1958. The experiments
proved that the DNA in chromosomes also replicate
semiconservatively.
(a) DNA polymerase is DNA dependent because it uses
DNA template to catalyse the polymerisation of
deoxynucleotides.
(b) Separation of the entire length of DNA helix needs
a large amount of energy. Hence, only up to certain
extent separation of DNA helix can take place.
(a) Replication fork is a Y-shaped structure formed due
to small opening of DNA helix for replication to take
place. This is formed because long DNA molecules
cannot be separated along the entire length (due to very
high energy requirement).
(b) The replication is continuous on 3′ → 5′ polarity
strand because DNA polymerase can catalyse
polymerisation in 5′ → 3′ direction only and we know
that DNA strands are complementary to each other.
Thus, continuous synthesis occurs in 3′ → 5′ direction.
(c) During DNA replication, super coiling is relaxed by
DNA topoisomerase. These enzymes participate in
underwinding of DNA.
Other options functions as,
l SSBPs are single strand binding proteins which
stabilises the unwound parental DNA.
l
Primase is the enzyme which synthesise RNA primer
on DNA template to initiate DNA synthesis.
l
RNA polymerase enzyme helps in synthesis of new
DNA strand during replication.
(d) Okazaki fragments are short segments of replicating
DNA. These have 1000-2000 bp in prokaryotes and
100-200 bp in eukaryotes. These fragments are formed
discontinuously and are used to elongate the lagging
strand away from the replication fork.
69 (b) Option (b) is correct. The phosphorylated
nucleotides are deATP (deoxy Adenosine
Triphosphate), deCTP (deoxy Cytidine Triphosphate),
deTTP (deoxy Thymidine Triphosphate). These
triphosphates serve dual purpose. These act as substrate
as well as provide energy for polymerisation of
nucleotides by releasing energy after dissociating the
phosphate group.
70 (a) Option (a) contains the wrongly matched pair and
can be corrected as
Transcription is a process of RNA synthesis from a
DNA template.
Rest of the options contain correct pairs.
71 (a) The strands in the DNA are complementary to each
other, not identical. If the two RNAs are formed from
both strands then RNAs with different sequences would
be formed.
Answers & Explanations
34
indicates that DNA is condensed into chromatin fibre.
In eukaryotes, DNA packaging is carried out with the
help of histone proteins. Nucleosome is the unit of
compaction. Its core consists of four pairs of histones
(H2A, H2B, H3 and H4). The linker DNA, consisting of
H1 histone connects two adjacent nucleosomes.
These together constitute chromatosome. It gives rise to
a chromatin fibre after further condensation.
(d) Frederick Griffith (1920) conducted a series of
experiments on the bacterium Streptococcus
pneumoniae. Through his experiment he found out that
the heat-killed S-strain bacteria had changed the
R-strain to virulent form. He called this the
transforming principle.
(c) In Griffith’s experiment, he found out that
something from dead organism could change the living
cells. From his experiment he showed that dead
S-bacteria (virulent) are changing (transforming) the
R-bacteria (non-virulant) into S-type, i.e. the virulent
strain.
(c) Alfred Hershey and Martha Chase (1952)
experimentally proved that DNA is the sole genetic
material in bacteriophage.
On the other hand, Beadle and Tatum (1940s)
experimentally showed one gene-one enzyme
hypothesis using Neurospora.
Meselson and Stahl first showed that DNA replicates
semiconservatively through experiments on E. coli.
Jacob and Monod were first to explain lac operon.
(a) Hershey and Chase grew cultures of Escherichia
coli. One culture was supplied with radioactive sulpur
( 35 S) and the another with radioactive phosphorus ( 32 P).
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Master The NCERT > BIOLOGY (Vol-II)
structures are not a part of RNA polymerase. Thus,
RNA polymerase can perfom the function of elongation
only.
72 (d) Option (d) is correct.
73
75
78
79
80
81
Answers & Explanations
82
84
85
87
If both strands are copied during transcription, then two
complementary RNA strands will be produced
simultaneously. These would have the tendency to form
double-stranded RNA and if these two RNA strands do
not form double helix these would code for two different
types of proteins. Then, the whole exercise of
transcription would be futile.
(a) If double-stranded RNA is produced during
transcription this would prevent RNA from being
translated into proteins. Double-stranded RNA have
more stability than single-stranded RNA. If
double-stranded RNA is formed from transcription, then
it is difficult to separate the strands of RNA due to
which translation would be halted.
(a) The strand, which does not code for anything is
referred to as coding strand. All the reference point,
while defining a trancription unit is made with the
coding strand.
(c) Coding strand is the one that codes for mRNA. It has
same nucleotide sequence as that of mRNA except
thymine (T) is replaced by uracil (U) in mRNA. Hence,
the corresponding sequence of transcribed mRNA by
template or non-coding strand (complementary to RNA)
is AGGUAUCGCAU.
(a) Among the given options, only the mRNA given in
option (a) can be transcripted because it possesses an
initiation codon-AUG which codes for methionine. Rest
of the mRNA sequences start with termination codons,
i.e. UAA (Ochre), UAG (Amber) and UGA (Opal).
Therefore, these cannot be transcripted.
(b) Option (b) gives the sequence of mRNA produced
by the given stretch of DNA. The mRNA will be
complementary to the DNA strand, but in RNA, uracil
will be present in place of thymine. If the template
strand is 3′–ATGCATGCATGCATG–5 then the base
sequence of mRNA for the given DNA strand will be
5′–UACGUACGUACGUAC–3’.
(b) Promoter is present at the 5′-site of structural gene
and terminator is present at the 3′-site of structural
genes. Thus, we can say that promoter and terminator
flanks the structural genes.
(c) Option (c) is incorrect and can be corrected as
Cistron is a segment of DNA coding for a polypeptide.
Rest of the options are correct.
(a) rRNA is the most abundant form of RNA; because it
is responsible for coding and protein synthesis in the cell
and is also associated with ribosomes.
(a) DNA-dependent RNA polymerase catalyses
transcription on one strand of the DNA called as
template strand. A template can be considered as one of
those strands of DNA which decodes its information
directly through RNA polymerase.
(b) RNA polymerase only catalyses the elongation
process of transcription. The initiation of transcription is
done by sigma (σ) unit. The termination of the
transcription is acheived by rho (ρ) factor. These two
88 (*) This question is incorrect because out of the given
initiation and termination factors, none is involved in
transcription in eukaryotes.
However, option (a) contains initiation and termination
factors which are involved in transcription. These
factors (σ and ρ) initiate and terminate transcription in
prokaryotes (not in eukaryotes). Initiation and
termination factors involved in transcription in
eukaryotes are General Transcription Factors (TF IIA TF II H) and Transcription Termination Factor-1
(TTF-1), respectively.
90 (c) Option (c) is correct.
In prokaryotes, mRNA does not require any processing
to become active and there is no clear demarcation
between the nucleus and cytoplasm. Genetic material is
dispersed through out the cytoplasm. Thus,
transcription and translation takes place in the same
compartment in prokaryotes.
91 (c) In the process of transcription (i.e. copying of
92
93
95
97
genetic information from one strand of the DNA into
RNA) in eukaryotes, the enzyme RNA polymerase-I
transcribes rRNA - 28S, 18S and 5.8S.
On the other hand, tRNA, 5srRNA and snRNAs are
transcribed by RNA polymerase III. RNA
polymerase-II transcribes precursor of mRNA, i.e.
hnRNA.
(a) RNA undergoes a process where the introns
(non-coding parts) are removed and exons (coding
sequence) are joined to form mRNA. This process is
called splicing.
(d) Spliceosome is absent in cells of bacteria. It is a
large molecular complex found in nucleus of eukaryotic
cells of plants, animals and fungi. It is assembled from
snRNAs and protein complexes which play an
important role in splicing of introns.
(c) At the 5′ end of eukaryotic mRNA, 7 mG (7-methyl
guanosine) is present. In eukaryotes, primary transcript
is often larger than the functional RNAs. Therefore,
post-transcription processing is required to convert
primary transcript of all types of RNAs into functional
RNAs. It is of four types; cleavage, splicing, terminal
addition and nucleotide modification.
The terminal additions include capping and tailing. In
capping, 7 mG is added to 5′ end of mRNA.
(a) Fully processed hnRNA to undergo translation is
called mRNA. hn (heterogenous nuclear) RNA is the
raw form of mRNA containing both introns and exons.
After splicing and post-transcriptional modification of
hnRNA, mRNA is formed.
104 (b) Polynucleotide phosphorylase enzyme is used in
polymerising RNA with defined sequences in a
template independent manner (enzymatic synthesis of
RNA). It is also called Servo Ochoa enzyme.
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CHAPTER 06 > Molecular Basis of Inheritance
109
113
114
115
117
118
119
121
123
64 codons. The rest three are non-sense codons which
are used for stopping translation. These are also called
stop codons.
(b) UAC is not a stop codon. It codes for tyrosine amino
acid.
The last codon of a functional gene which helps in
termination of the polypeptide chain, is termed as stop or
termination codon. These are UAA, UAG and UGA.
These codons do not have tRNA to be translated.
(d) Degeneracy refers to the fact that one amino acid has
more than one code triplet and the codons which specify
the same amino acids differ only in the third base of the
triplet, e.g. both CAC and CAU code for the amino acid
histidine.
(b) Bacteria is able to produce human insulin because
genetic code is nearly universal in all organisms. For
example, the codon AGG specifies amino acid arginine in
bacteria, animals and plants.
But there are also some exceptions, e.g. in mitochondria,
the stop codon UGA for humans specifies amino acid
tryptophan.
(a) Mutation gives rise to alterations in the phenotype.
This is the reason as to why mutation is best for studying
the relationship between genes and DNA for their
expression.
(c) The reading frame of given mRNA will not change
even after the deletion of GGU from 7th, 8th and 9th
positions. However, only the amino acid glycine will not
be formed at third position in this case which is being
coded by GGU.
In rest of the cases, insertion or deletion of one or two
nucleotide bases would result in the complete alteration
in the reading frame of mRNA.
(c) 33 codons will be altered if the base at position 901 is
deleted from an mRNA having 999 bases. This can be
calculated as
Total number of bases in the given mRNA = 999
999
Number of codons for this mRNA =
= 333
3
If one base is deleted at position 901 then the number
900
bases unchanged are 900 which codes for
3
= 300amino acids
Thus, number of altered codons will be
333 − 300 = 33
(a) Frameshift mutation of the genetic bases (deletion or
addition) gives the proof that codon is triplet and reads in
contagious manner. Deletion or addition of a base pair
disturb the reading frame of DNA or mRNA.
(c) tRNA was known as sRNA (soluble RNA) before the
genetic code was postulated. Its role as an adaptor
molecule was reported later.
(c) Option (c) is incorrect and can be corrected as
tRNA are specific for each amino acid, e.g. for initiation
there is a specific initiator tRNA.
Rest of the options are correct for tRNA.
124 (c) Three dimensional structure or compact form of
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135
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139
tRNA was given by Klug in 1974. It looks like the
letter 'L' of English alphabet. Hence, it is called as the
L-form model of tRNA.
(a) tRNA binds to mRNA through anticodon loop, as
it bears bases complementary to those on mRNA being
translated.
The amino acid loop of tRNA is involved in binding
the respective amino acid. The T ψ C loop helps in
binding the amino acid, while the D-loop of tRNA is
the binding site for aminoacyl synthetase.
(a) RNA polymerase-III transcribes the synthesis of
tRNA, therefore tRNA synthesis will be affected if it
is removed from nucleoplasm. RNA polymerase-II
synthesises mRNA while, RNA polymerase-I
synthesis rRNA in eukaryotes.
(c) Polysome is a string of ribosomes associated with
a single mRNA. Polysome helps to produce a number
of copies of the same polypeptide.
(a) In the process of protein synthesis, tRNA carrying
the amino acids enters the A-site of the ribosome.
Peptide bonds that are formed between the amino
acids are present on P and A-site.
(b) According to the sequences present on the
mRNA, amino acids are produced. Thus, the order
and the sequence of the amino acids are defined by
mRNA.
(c) UTRs present on mRNA refer to Untranslated
Regions present at both 5′–end (before start codon)
and 3′–end (after stop codon). These are the additional
sequences that are not translated. These are required
for efficient translation process.
(c) Option (c) contains the incorrect match and can be
corrected as
A translational unit in mRNA is the sequence of RNA
that is flanked by the start codon (AUG) and ends at
the stop codon and codes for a polypeptide.
Rest of the matches are correct.
(d) Option (d) represents the correct sequential code
of tRNA. DNA and mRNA have complementary base
pairs.
If the DNA is 3′–TAC ATG GGT CCG–5′
than mRNA will have
II
I
IV
III
5′–AUG UAC CCA GGC–3′
tRNA and mRNA have complementary base pairs.
(c) Option (c) is correct as UAA, UAG and UGA are
stop codons on mRNA for which no tRNA molecules
are present. tRNA molecules have anticodon,
therefore anticodons for the mentioned stop codons
will AUU, AUC and ACU which does not exist.
144 (a) Positively regulatory proteins are called
activators. These activator proteins bind to regulatory
sites on DNA near to the promoter regions which act
as on / off switches. This binding facilitates RNA
polymerase activity and transcription of nearby genes.
Answers & Explanations
105 (c) 61 codons code for amino acids out of the total
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145 (c) In the operon system, the promoter is generally
situated beside the operator genes. In the prokaryotes,
the working of promoter region (binding of RNA
polymerase) is coordinated by the operator genes, e.g. if
operator genes are occupied by the repressor proteins
then RNA polymerase does not bind to the promoter
gene and there is no transcription.
157 (a) An inducer binds with the repressor protein and
160
146 (b) An operon is considered to regulate genetic unit or
DNA. It act as a single regulatory unit having one or
more structural genes, an operator gene, regulator
genes, a repressor and an inducer.
148 (d) Option (d) is the correct match.
Jacob and Monod (1916) discovered the lac operon.
Rest of the matches are incorrect and can be
corrected as
l Matthew Meselson and F Stahl discovered the
semiconservative mode of DNA replication in E. coli.
l Alfred Hershey and Martha Chase use
T2
bacteriophage in their experiments to infect E. coli
and proved that DNA is the genetic material.
l Alec Jeffreys (1984) invented the DNA
fingerprinting technique. This technique determines
nucleotide sequences of certain areas of DNA which
are unique to each individual.
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164
149 (b) A lac operon has one regulatory gene (i.e. i-gene)
150
Answers & Explanations
151
153
156
and three structural genes (i.e. z, y and a genes).
(b) Gene regulation governing lactose operon of E. coli
that involves the Lac i gene products is negative and
inducible because its repressor protein prevents
transcription.
Lac i gene produces an inhibitor or repressor that
induces negative regulation of lac operon.
The repressor binds to the operator gene and stops its
working. Repressor is meant to block the operator gene,
so that structural genes are unable to form mRNA, thus
stopping the transcription of genes.
On the other hand, lactose operon is inducible operon
system. It is a regulated unit of genetic material which
is switched on in response to the presence of a chemical.
(a) β-galactosidase enzyme will be produced in a cell in
which non-sense mutation takes place in the lac y gene.
Non-sense mutation stops polypeptide synthesis due to
the formation of non-sense codon. In lac operon,
sequence of structural genes is z (codes for
β-galactosidase), y (permease) and a gene
(transacetylase). Due to non-sense mutation at y-gene,
permease synthesis will be stopped resulting in
non-expression of both y and successive gene a also.
Thus, only β-galactosidase enzyme will be produced.
(c) Lactose is the substrate for the enzyme beta (β)
galactosidase and it regulates the switching on and off
of the lac operon. Hence, it is termed as inducer.
(a) Repressor protein attaches to the operator gene. It is
a regulatory protein synthesised by regulator gene.
Repressor is meant for blocking the operator gene, so
that the structural genes are unable to form mRNA.
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prevents the repressor protein from binding to the
operator.
Glucose and galactose cannot act as an inducer because
these do not have the binding sites for attaching the
repressor protein.
(d) Option (d) is incorrect and can be corrected as
During human genome project many non-human
organisms such as bacteria, yeast, C. elegans,
Drosophila, plants, etc. DNA were also sequenced.
Rest of the options are correct.
(c) Gene or DNA library is a collection cloned or copied
DNA (cDNA) of cells or tissues, organs of
an organism in a preserved form for future use.
(b) Option (b) is the incorrect match and can be
corrected as
Sequence annotation is simply sequencing the whole set
of genome that contained all the coding and non-coding
sequence and later assigning different regions in the
sequence with functions.
Rest of the matches are correct.
(c) For generating genetic and physical maps,
restriction endonuclease was used. For sequencing the
human DNA, the entire DNA from a cell is isolated and
converted into random fragments of relatively smaller
size by using restriction endonuclease enzyme and
cloned in suitable host using specialised vectors.
(d) Chromosome number 21, 22 and Y are listed in G
group. To make chromosomal studies easier,
chromosomes are classified into Groups A to G as given
below.
Group A contains 1-3 chromosomes
B contains 4-5 chromosomes
C contains 6-12 chromosomes and X-chromosome
D contains 13-15 chromosomes
E contains 16-18 chromosomes
F contains 19-20 chromosomes
G contains 21-22 chromosomes and Y- chromosome
(a) Human genome is said to have approximately
3 × 109 bp, but the exact number is 3164.7 million bp.
(d) Option (d) is correct as reptitive sequences are
stretches of DNA sequences that are repeated many
times, (sometimes hundred to thousand times). These
are thought to have no direct coding functions, but these
shed light on chromosome structure, dynamics and
evolution.
(d) Option (d) is incorrect and can be corrected as
Repetitive DNA sequences are stretches of DNA
sequences that are repeated many times, sometimes
hundred to thousand times.
Rest of the options are correct.
(c) There are about 1.4 million locations where single
base DNA differences occurs. These locations are called
SNPs (snips) or Single Nucleotide Polymorphism in
humans.
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176 (b) Sattelite DNA is important because it shows high
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189
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191
degree of polymorphism (variation at genetic level) in
population and also the same degree of polymorphism
in an individual, which is heritable from parents to
children. Also satellite DNA does not code for proteins
or enzymes but are different in all the members of a
population.
(c) PCR (Polymerase Chain Reaction) is the technique
in which many copies of DNA can be produced in a
short period of time. It can increase the sensitivity of
DNA fingerprinting.
(a) In Southern blotting DNA is transferred from
electrophoresis gel plate to the nitrocellulose or nylon
membrane sheet.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
DNA serves as the genetic material in most organisms,
but in some viruses like TMV, RNA acts as the genetic
material. DNA is a double-stranded biomolecule, but
can also exist as a single-stranded biomolecule.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
The two chains of DNA have antiparallel polarity. This
is because one chain has a free phosphate moiety at the
5′ end of the ribose sugar and another chain has a free
phosphate moiety at the 3′ end.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
Adenine cannot pair with cytosine. Adenine pairs with
thymine and cytosine pairs with guanine. This occurs
because adenine pairs with thymine with two hydrogen
bonds, i.e. have only two hydrogen donor / hydrogen
acceptor sites whereas cytosine has three hydrogen
donor / hydrogen acceptor sites. Thus, due to lack of
complementarity between the hydrogen donor and
hydrogen acceptor sites between adenine and cytosine,
these cannot pair.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
Histones are basic in nature because these are rich in
amino acids lysine and arginine which are basic in nature.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Heterochromatin is densely packed and inaccessible to
transcription factors. Hence, it is rendered
transcriptionally silent or inactive.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
RNA is an unstable catalytic molecule. It mutates at a
faster rate than DNA. Thus, viruses having RNA
genome and shorter lifespan, mutate and evolve faster
due to this unstability.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
The DNA-dependent DNA polymerase works in the
5′ → 3′ direction requiring a free 3′–OH of a
pre-existing polynucleotide for initiating DNA
192
193
194
195
196
197
replication. Thus, it continuously synthesises the strand
having polarity 3′ → 5′.
Replication of the lagging strand (5′→ 3′) generates
small polynucleotide fragments, okazaki fragments. The
replication of this strand is discontinuous.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
In eukaryotes, replication and transcription take place in
the nucleus.
The fully processed hnRNA now called mRNA, is
transferred from the nucleus into the cytoplasm, where
translation occurs.
This is because all the amino acids, tRNA and
ribosomes required for translation are present in the
cytoplasm.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
The primary transcript in eukaryotes, i.e. the hnRNA is
much larger as it contains both introns and exons. It is
the precussor of mRNA. During post-transcriptional
modification. Introns (the intervening sequences),
which do not code for proteins are removed and all
exons are joined to form fully prossessed mRNA.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Polycistronic mRNA, commonly found in prokaryotes,
two or more coding regions are present and can specify
a number of polypeptide chains or proteins. It further
contains multiple (open) reading frames to enable the
formation of two or more proteins.
Both polycistronic and monocistronic mRNAs have a 5′
leader sequence, the coding region (containing initiation
codon and termination codon) and a non-translated 3′
trailer sequence.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
In transcription, the strand with 3′ → 5′ polarity acts as
the template from which mRNA is transcribed as is
called the template strand.
This is because the enzyme DNA-dependent RNA
polymerase catalyses polymerisation in only 5′ → 3′
direction.
(b) Both the Assertion and Reason are true, but Reason
is not the correct explanation of Assertion.
In eukaryotes, transcription, i.e. synthesis of RNA from
DNA, occurs inside nucleus, because the genetic
material DNA is enclosed within the nucleus in
eukaryotes.
In prokaryotes like bacteria, the genetic material, DNA
remains suspended within the cytoplasm. Thus, in
prokaryotes the processes of transcription and
translation occur in cytoplasm.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
The genetic code is degenerate. It means that a given
amino acid can be coded by more than one codon. For
example, serine is an amino acid coded by UCU, UCC,
UCA, UCG, AGU and AGC.
Answers & Explanations
157
CHAPTER 06 > Molecular Basis of Inheritance
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198 (b) Both Assertion and Reason are true, but Reason is
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Answers & Explanations
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210
not the correct explanation of Assertion.
mRNA has some additional sequences that are not
translated known as Untranslated Regions (UTR). The
UTRs are present at both 5′ end (before start codon) and
at 3′ end (after stop codon). These are required for
efficient translation process.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
DNA fignerprinting is very well-known for its
application in paternity testing as it employs the
principle of DNA polymorphism. DNA fingerprinting
involves the use of satellite DNA. These sequences do
not code for any proteins, but show high degree of
polymorphism.
These serve as the basis of DNA fingerprinting. These
polymorphisms are inheritable from parents to children
and thus DNA fingerprinting is the basis of paternity
testing.
(b) Statements I, II, III and IV are correct.
Statement V is incorrect and can be corrected as
Ribose sugar can be represented as C5 H10 O5 whereas
deoxyribose sugar (has deficit of one oxygen atom) can
be represented as C5 H10 O4 .
(c) The statement in option (c) is incorrect and can be
corrected as
Nucleotides do not have proteins, carbohydrates and
fats. Nucleotides contain a sugar, a phosphate group and
a nitrogenous base.
Rest of the statements are correct.
(c) Statements I, II and IV are correct. Statement III is
incorrect and can be corrected as
Transforming principle is associated with genetic
material of S-strain.
(d) Statements I, II and IV are correct.
Statement III is incorrect and can be corrected as
35
S will end up in the supernatant after centrifugation as
sulphur is present in proteins.
(c) The statement in option (c) is incorrect and can be
corrected as
Equal amount of heavy DNA and light DNA was
observed in E. coli culture after the two generations.
Rest of the statements are correct.
(c) The statement in option (c) is incorrect and can be
corrected as
Meselson and Stahl proposed the semiconservative
DNA replication scheme.
Rest of the statements are correct.
(a) The statement in option (a) is correct.
Rest of the statements are incorrect and can be corrected
as
l
Exon is the coding or expressed sequence, intron is
the non-coding sequence and cistron is the segment
of DNA which codes for a polypeptide.
The region of DNA where transcription starts is
promoter.
l The terminator codes for the end of transcription.
212 (c) The statement in option (c) is incorrect and can be
corrected as
The coding sequences or expressed sequences are called
exons. Intervening sequences or non-coding sequences
in an unprocessed RNA are called introns.
Rest of the statements are correct.
214 (d) Statements II and III are correct. Statements I and
IV are incorrect and can be corrected as
l rRNA provides the site for protein synthesis.
l A segment of DNA coding for polypeptide is called
cistron.
l
216 (b) Statements II and III are correct.
Statements I and IV are incorrect and can be corrected
as
l
mRNA does not have an elaborated 3 D structure, it
is a linear chain.
l
mRNA contains codons and tRNA contains
anticodons.
217 (d) Steps in statements I, II and III are related with
tRNA as these are steps of polypeptide synthesis, i.e.
translation. Steps in statement IV is not related with
tRNA.
This is because transcription involves copying of
genetic information from the template DNA strand to
RNA. tRNA does not participates inthis process.
218 (c) Statements II and IV are correct. Statements I and
III are incorrect and can be corrected as
l
Glucose and galactose are formed from allolactose
by β-galactosidase. These bind with the lactose
repressor and activate it is enable the transcription
process.
l
Tryptophan acts as repressor to stop gene
expression.
219 (d) Statement II, III and IV are incorrect and only
statement I is correct.
This can be explained as in lac operon model,
regulatory gene is continuously working, whether
lactose (inducer) is present or not. It transcribes mRNA
which codes for repressor.
When this repressor binds with lactose (inducers) it
inhibits translation of operator gene (not R gene).
Thus, lactose presence affects operator gene not R
gene.
220 (d) The statement in option (d) is incorrect and can be
corrected as
The repressor of the operon is synthesised (all-the-timeconstitutively) from the i gene. The repressor protein
binds to the operator region of the operon and prevents
RNA polymerase from transcribing the operon.
Rest of the statements are correct.
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CHAPTER 06 > Molecular Basis of Inheritance
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243
244
245
246
247
248
corrected as
Less than 2% of the genome codes for proteins.
In most of organisms more than 98% of human genome is
composed of non-coding DNA (or Junk DNA).
Rest of the statements are correct.
(a) The statement in option (a) is incorrect and can be
corrected as
BAC or Bacterial Artificial Chromosome and YAC or
Yeast Artificial Chromosome are the two vectors
generally used in human genome project for cloning the
large fragments of human DNA.
Rest of the statements are correct.
(c) A nitrogenous base is attached to the pentose sugar by
an N-glycosidic linkage to form a nucleoside, i.e.
Nucleoside=Nitrogen base + Pentose sugar.
When a phosphate group is attached to the 5′-OH of a
nucleoside through phosphodiester linkage, a nucleotide is
formed, i.e. Nucleotide = Nitrogen base + Pentose sugar +
Phosphate (PO4 ).
So, a nucleoside differs from a nucleotide as it lacks
phosphate group.
(c) Both deoxyribose and ribose belong to the class of
sugar called pentoses as these sugars contain five carbon
atoms.
(c) The diameter of the strand is always constant due to
the pairing of a purine (adenine and guanine) with a
pyrimidine (cytosine and thymine). This specific bonding
gives uniform width throughout the DNA.
(d) Option (d) is correct. rRNA, mRNA and tRNA are the
major classes of RNAs that are involved in gene
expression. Their functions include
rRNA binds protein molecules and forms a ribosome.
mRNA carries coded information for translation and
polypeptide formation.
tRNA is called soluble or adaptor RNA which carries
amino acids to ribosomes during protein synthesis.
(d) Meselson and Stahl had no contribution in the
development of double helix model. In 1958, Meselson
and Stahl performed experiments on E. coli to prove that
DNA replication is semiconservative.
(b) According to Chargaff’s rule of base pairing
A G
i.e.
= =1
T C
For the given organism, the DNA does not follow
A 27 32 G
Chargaff’s rule as =
=/
= =/ 1
T 17 17 C
Hence, it can be concluded that it is a single-stranded
DNA, not double-stranded.
(c) In some viruses, like retroviruses (e.g. HIV),
complementary DNA (cDNA) is synthesised by using an
RNA template. This process is termed reverse
transcription and an enzyme called reverse transcriptase is
used.
249 (c) The net electric charge on DNA and histones is
negative and positive, respectively.
DNA consists of a nitrogenous base, pentose sugar
and a phosphate group. DNA has negative charge due
3−
to the presence of phosphate group (PO4 ). Histones
are rich in basic amino acid residues lysine and
arginine, which carry positive charge in their side
chains. Therefore, histones are positively charged.
250 (d) The first genetic material could be RNA. We
know that RNA is present as a genetic material in some
viruses, and it also works as a catalyst (there are some
important biochemical reactions in living systems that are
catalysed by RNA catalysts and not by protein enzymes).
But, RNA being a catalyst is reactive and hence unstable.
Therefore, it is considered that DNA has evolved
from RNA thereby making RNA the first genetic
material.
251 (d) Option (d) is correct.
Meselson and Stahl found that DNA of the first
generation was hybrid or intermediate (15 N and 14 N).
It settled in caesium chloride at a level higher than the
fully labelled DNA of parent bacteria (15 N 15N ).
The second generation of bacteria after 40 minutes,
contained two types of DNA, 50% light ( N14 N14 ) and
50% intermediate ( N15 N14 ).
The third generation of bacteria after 60 minutes
contained two types of DNA, 25% intermediate
( N15 N14 ) and 75% light ( N14 N14 ) in 1 : 3 ratio.
It can be assumed that the fourth generation after
80 minutes would contain 12.5% N15 N14 and 87.5%
N14 N14 DNA in 1:7 ratio.
Thus, if Meselson and Stahl’s experiment is continued
for four generations in bacteria, the ratio of 15 N / 15 N
:15 N / 14 N : 14 N / 14 N containing DNA in the fourth
generation would be 0 : 1 : 7.
252 (b) To prevent polymerisation of nucleotides, 3′ OH
group in deoxyribose should be replaced/removed.
This is because DNA polymerase enzyme requires a
free 3′–OH end of pre-existing polynucleotide to
enable polymerisation, leading to the formation of a
continuous strand in the 5′→ 3′ direction.
254 (a) Option (a) gives the correct sequence of bases in
the RNA transcript for the given DNA coding strand.
5′ - A T G A A T G - 3′ (coding strand)
↓
3′- T A C T T A C - 5′ (template strand)
↓
5′ -A U G A A U G - 3′ (RNA)
255 (b) The promoter is located towards 5′ end
(upstream) of the structural gene of coding strand and
provides the binding site for RNA polymerase to
initiate transcription. The terminator region is where
the transcription stops and it is present at the 3′ end
(downstream).
Answers & Explanations
221 (b) The statement in option (b) is incorrect and can be
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Master The NCERT > BIOLOGY (Vol-II)
257 (b) RNA polymerase catalyses elongation during
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260
261
263 (b, c) Both options (b) and (c) are correct.
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267
In eukaryotes, the regulation of gene expression is
exerted at transcriptional level (formation of primary
transcript), processing level (regulation of splicing),
transport of mRNA from nucleus to the cytoplasm
and translational level.
While, in prokaryotes, control of the rate of
transcriptional initiation is the predominant site for
control of gene expression.
(a) When lactose is present, it act as an inducer and
binds to the repressor and inactivates it. This
repressor fails to bind to operator. Therefore, the
RNA polymerase binds to the promoter and transcript
lac mRNA thus switching on the lac operon and
allowing transcription to proceed.
(d) Option (d) is correct.
In a transcription unit, the activity of RNA
polymerase at a given promoter is regulated by
interaction with accessory proteins, which affects its
ability to recognise start sites. These regulatory
proteins can act both positively (activators) and
negatively (repressors).
(a) Chromosome 1 was the last completed
chromosome, sequenced two decades after the
beginning of the human Genome Project (hGP). It is
designated as the largest human chromosome.
(c) The human chromosomes having the highest and
least number of genes, respectively are chromosome
1 with 2968 genes and chromosome-Y with
231 genes.
Answers & Explanations
262
transcription. During elongation RNA polymerase ‘walks’
along one strand of DNA known as the template strand in
the 3’ → 5’ direction. For each nucleotide in the template
RNA polymerase adds a matching (complementary) RNA
nucleotide to the 3’ end of the RNA strand. It associates
transiently with initiation factor (σ) and termination factor
(ρ ) to initiate and terminate the transcription, respectively.
(b) In mRNA of eukaryotes exons appear, but introns do
not. This is because introns are intervening or non-coding
sequences and exons are coding or expressed sequences.
Through splicing introns are removed and exons are joined
to form mRNA.
(a) To initiate translation, the mRNA first binds to the
smaller ribosomal subunit.
Ribosome consists of structural RNAs and about
80 different proteins. In its inactive state, it exist as two
subunits, a large subunit and a small subunit. When the
smaller subunit encounters the mRNA, the process of
translation of the mRNA to protein begins with the binding
of the mRNA to the smaller ribosome unit.
(b) The first base of anticodon in 5′ → 3′ direction binds
with the third base in codon (reading in 5′ → 3′ direction).
Thus, if the base sequence in codon of mRNA is 5′ – AUG
– 3′ the complementary anticodon will be 3′ – UAC – 5′ or
5′ – CAU – 3′.
(b) AA-binding site (amino acid binding site) lies at the
3′ end opposite the anticodon and has CCA-OH group.
Thus, the site where amino acid attaches to the tRNA is
the 3′ end of the tRNA molecule.
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CHAPTER > 07
Evolution
NEET
KEY NOTES
Å
The origin of life is considered a unique event in the history
of universe. The study of history of life forms on the earth is
called evolutionary biology.
Å
Evolution is the process that results in heritable changes in
population spread over many generations leading to
diversity of organisms on earth.
Origin of Life
Å
It is considered a unique event in the history of our universe.
Å
Our universe is about 20 billion years old. It comprises of
huge clusters of galaxies.
Å
Various theories given by different thinkers and scientists to
explain origin of life are described below
Å
The Big Bang theory attempted to explain the origin of
universe. According to this theory, a single huge explosion
resulted in universe expansion, decreased temperature,
condensation of gases, formation of hydrogen and helium,
etc., which resulted in formation of galaxies.
Å
Earth is about 4.5 billion years old.
Å
Life appeared 500 million years after the formation of earth.
Å
Theory of special creation states that God created life by his
divine act of creation.
Å
Theory of cosmic panspermia (by early Greek thinkers)
states that the spores or panspermia came from outer space
and developed into living forms.
Å
Theory of spontaneous generation states that the life
originated from decaying and rotting matter like straw, mud,
etc. Louis Pasteur rejected the theory of spontaneous
generation and demonstrated that life came from
pre-existing life and gave theory of biogenesis.
Å
Theory of chemical evolution or Oparin-Haldane theory
states that life originated from pre-existing non-living
organic molecules (e.g. RNA, protein, etc.) and the formation
of life was preceded by chemical evolution.
Å
The conditions on the earth that favoured chemical evolution
were very high temperature (800ºC), volcanic storms and
reducing atmosphere that contained CH4 , NH3 , water
vapours, etc.
Å
In 1953, SL Miller and his student H Urey created primitive
earth conditions in the laboratory and provided
experimental evidence for chemical evolution. They clearly
demonstrated that electrical discharges or UV radiations or
both can create organic compounds from mixture of gases
( CH4 , NH3 and H2 in the ratio of 2 : 1 : 2 and water vapours)
in the experiment.
Origin of First Cell
Å
First non-cellular life form originated 3 billion years ago.
These molecules were like RNA, protein and polysaccharides
inside a self-replicating metabolic capsule which later
reproduced its molecules.
Å
Cellular life form first evolved about 2000 million years ago.
These were single-celled and formed in aquatic environment.
Å
This form of abiogenesis, i.e. the first form of life arose
slowly through evolutionary forces from non-living
molecules, was accepted by many scientists.
Biological Evolution
Å
It is the process of inheritance of genetic changes over
several generations. Unlike chemical evolution, biological
evolution happens when organisms could replicate. It took
place in following steps – Coacervates formation, formation
of protobionts, origin of prokaryotes and eukaryotes.
Å
Coacervates were aggregate of organic biomolecules,
surrounded by film of water molecules. They lack definite
membrane, but do exhibit some life like characters.
Å
Microspheres were the non-living collections of organic
macromolecules double-layered and can be formed from
proteinoids, by heating a mixture of amino acids at 180ºC.
Å
The first organisms originated in reducing (oxygen free)
atmosphere were anaerobes (able to respire in the absence of
oxygen). They were called heterotrophs because they were
dependent on pre-existing organic molecules for obtaining
nutrition. Some of them might have evolved into autotrophs.
Å
The doctrine of organic evolution states that the present
complex organisms (eukaryotes) have been produced by
gradual changes in the earlier simpler forms (prokaryotes) of
life over ages.
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Å
Charles Darwin during a sea voyage on his ship HMS Beagle
concluded that existing living forms share similarities among
themselves and with life forms that existed million of years
ago.
n
Evidences of Evolution
Evidences that the evolution of life forms took place on earth
came from palaeontology, comparative anatomy and
morphology, biochemical evidences and biogeographical
evidences.
Å
Palaeontology is the study of fossils in different sedimentary
layers, indicating the geological period in which they existed.
Å
Geological time scale is a chronological order or history of
evolution based upon the study of fossils. It has been divided
into eras, periods and epochs.
Å
Embryological evidences These were given by Ernst Haeckel.
He observed structures common in embryonic stage of all
vertebrates, like presence of gill slits in all vertebrates embryo
including human, but these were functional only in fish and
absent in all other adult vertebrates. However, this proposal
was disapproved by Karl Ernst von Baer.
Å
Biochemical similarities These are seen in proteins and genes
performing a given function among diverse organisms. This
gives clue to common ancestry among diverse organisms.
Å
Comparative anatomy and morphology show similarities and
differences among the organisms of today and those of earlier
times.
n
n
n
Å
Various theories regarding evolution of species, i.e.
biological evolution have been postulated by different
evolutionists. Some of them are as follows
Lamarckism
Å
Lamarckism (‘Inheritance of Acquired Characters in
Organisms’) is given by Lamarck in 1809. It states that
changes in structure or function of organ acquired
during an individual’ lifetime in response to changes
in the environment are inherited by its offspring.
Major postulates of this theory are as follows
Å Internal vital force
Å Effect of environment and new needs
Å Use and disuse of organs
Å Inheritance of acquired characters
This theory was rejected by August Weismann
(1892) who proposed the ‘Theory of Continuity of
Germplasm’ that states characters influencing
germ cells are only inherited.
Å
Neo-Lamarckism proposed that environment
influences an organism directly or indirectly (i.e.
produced variation) and changes its heredity, only
those variations are passed on to next generation
which affects germ cells.
Analogous organs are the organs which show superficial
resemblance and perform similar function, but have
different internal structure, e.g. flippers of penguins and
dolphins. These organs suggest occurrence of convergent
evolution.
Vestigial organs are non-functional organs, which were
functional in the ancestors of present organisms, e.g
nictitating membrane (3rd eyelid), coccyx, etc., in humans.
Adaptive radiation It is the process of evolution of
different species in a given geographical area starting from
one point and radiating to other habitats, e.g. Darwin
finches, Australian marsupials, etc.
NEET
Adaptive convergence in mammals Australian
marsupials and placental mammals in North
America provide another example of convergent
evolution. Despite the temporal and geographical
separation, marsupials in Australia and placental
mammals in North America have produced
varieties of species living in similar habitat with
similar ways of living. They are not related, but
resemble each other because they fill similar niches
in each continent.
Theories of Evolution
Homologous organs are the organs which show same
structure, but different functions, e.g. forelimbs of whales,
bats and cheetah. These organs suggest occurrence of
divergent evolution.
Biogeographical evidences It suggests that species restricted
to a region, develop unique features. Also, species present in
widely separated regions show similarity of ancestry. Habitat
isolation had probably restricted these organisms to a
particular geography on the earth. This can be explained with
the help of following processes
n
n
Adaptive convergence/convergent evolution When
more than one adaptive radiation appeared to have
occurred in an isolated geographical area
(representing different habitats) and two or more
groups of unrelated animals come to resemble each
other for similar mode of life or habitat, it is called
adaptive convergence or convergent evolution.
Darwinism
Å
Darwinism (Theory of Natural Selection) is given by
Charles Darwin in 1859. The essence of this theory is
natural selection. The environment selects those
individuals which are better fitted, and have adaptive
ability to survive and reproduce.
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CHAPTER 07 > Evolution
Å
The two key concepts of Darwinian theory of evolution are
described as follows
n
p 2 + 2pq + q 2 = 1
(i) Branching descent is defined as a process by which new
species originate from a single common descent.
where, p and q are individual frequencies of
different alleles. This is a binomial expansion of
( p + q) 2 . When frequency measured, differs from
expected values, the difference indicates the extent
of evolutionary change.
(ii) Natural selection states that organisms better adapted to
environment are selected by nature and they survive,
reproduce and pass their characters to next generations.
It leads to speciation (formation of new species).
n
An example of natural selection is industrial melanism in
peppered moths of England.
Before industrialisation (in 1850s), white peppered moths
were able to escape predation due to trees covered by
white coloured lichen, but after industrialisation, black
peppered moths increased and selected by nature due to
trees covered by black soot present in that region, i.e. the
proportion was reversed.
Mutation Theory of Evolution
(Mechanism of Evolution)
Å
In 1901, Hugo de Vries carried out experiments on evening
primrose plant (Oenothera lamarckiana) and proposed the
mutation theory of evolution.
Å
This theory states that the evolution occurs by the sudden
large differences in the population. He believed that mutation
is the only cause of evolution and not the minor heritable
variations that Darwin talked about.
Å
He stated that the mutation caused speciation and named it
saltation (single step large mutation). Mutations are random
and without directions, while, Darwinian variations are small
and directional.
Modern Synthetic Theory
of Evolution
Å
Å
With progress in genetics, the sources of variation were
explained and Darwin’s theory was modified.
Now, the most accepted theory of evolution is known as
modern synthetic theory of evolution, designated by Huxley
in 1942 in which the origin of species is based on the
interaction of genetic variation in a population, natural
selection and reproductive isolation.
Hardy-Weinberg Principle
Å
This principle states that allele frequencies in a population are
stable and are constant from generation to generation, i.e.
gene pool is constant.
Å
It occurs when population is large and there is random
mating among members of the population. This is called
genetic equilibrium or Hardy-Weinberg equilibrium.
Sum total of all allelic frequencies is 1. It can be
expressed by the following equation
n
Any fluctuation in genetic equilibrium leads to
evolution.
Factors Affecting
Hardy-Weinberg Equilibrium
The factors that affect Hardy-Weinberg equilibrium are
given below
Å
Gene migration or Gene flow Due to migration, new
genes or alleles are added to the new population and
these are lost from the old population, in turn changing
the frequencies. There would be a gene flow if this gene
migration happens multiple times. So, gene flow
changes the frequency of allele.
Å
Genetic drift The changes occurring in frequencies by
chance are called genetic drift. Sometimes due to
changes in allele frequency in new population, some
different species are formed. This is called founder
effect and the original drifted population is called
founder.
Å
Mutations These occur randomly and at very slow
rates. They lead to new phenotypes and due to the
considerable genetic variation, speciation occurs.
Genetic recombination During gametogenesis,
crossing over in meiosis leads to new combination of
genes.
Å
Å
Natural selection It occurs due to the inheritance of
variations, which leads to the survival of the fittest. So,
if above five factors are absent in a population it means
there is no evolution going on in that population. It has
following effects
n
n
n
Stabilisation Large number of individuals acquire
mean character value.
Directional change Large number of individuals
acquire value other than mean character value. It
means natural selection is taking place in one
direction.
Disruption More individuals acquire peripheral
character value at both ends of the distribution
curve.
NEET
KEY NOTES
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Here, natural selection takes place in two different directions.
Å
Peak gets
higher
and
narrower
Phenotypes favoured by
natural selection
Å
(a)
Medium-sized
individuals
are favoured
Peak shifts
in one
direction
Å
Å
(b)
Number of individuals
with phenotype
Two peaks formed
(c)
Diagrammatic representation of the operation of natural selection
on different traits, (a) Stabilising, (b) Directional and (c) Disruptive
A Brief Account of Evolution
Å
Å
Å
About 2000 million years ago (mya), the first cellular form
of life appeared on earth.
Some of these cells had the ability to release O2 by splitting
water molecule with the help of solar energy.
Slowly, single-celled organisms became multicellular life
forms.
Evolution of Plants
Plant’s evolution occurred before animals.
Å Bryophytes were the first plants to colonise land and were
evolved before the vascular plants like pteridophytes and
gymnosperms.
Å Vascular plants first originated in Silurian period.
Å Existence of sea weeds and few plants was reported
around 320 million years ago.
Å
Herbaceous lycopods and arborescent lycopods evolved
from Zosterophyllum of Palaeozoic era.
Å
Psilophyton is the common ancestor for horsetails, ferns
and gymnosperms.
Evolution of Animals
Å
First animals were invertebrates, which were formed
around 500 mya.
Å
Jawless fish and amphibious fish with stout and strong
fins originated around 350 mya.
Å
The first amphibians and ancestors of modern day frogs
were lobefins (Coelacanth). In 1938, it was caught in South
Africa which was thought to be extinct. It is a living fossil.
Å
Reptiles were evolved from amphibians. They lay
thick-shelled eggs that do not dry up in the sun like those of
amphibians. Reptiles dominated the earth, around 200 mya.
NEET
Å
Land reptiles were dinosaurs of which Tyrannosaurus rex
(about 20 feet in height) was the biggest. Some land
reptiles went back to water and evolved as fish-like
reptiles, e.g. Ichthyosaurs. About 65 mya, dinosaurs
disappeared from the earth.
In Triassic period, mammals appeared and the first
mammals were like shrews.
Mammals were viviparous and protected their unborn
young ones inside the mother’s body.
Mammals were more intelligent in sensing and avoiding
the danger.
Before continental drift, horse, hippopotamus, bear, rabbit,
etc., were present in South America, but afterward when
South America joined North America, these animals were
overhidden by North American fauna.
Origin and Evolution of Man
The fossil evidence clearly indicates that origin of man
occurred in Central Asia, China, Java and India
(Shivalik hills). Thus, the common ancestor of apes and
man was Dryopithecus.
Å The next stage was Ramapithecus in the hominid
evolution. Both were hairy and walked like gorillas and
chimpanzees. Few fossils of man-like bones have been
discovered in Ethiopia and Tanzania.
Å These revealed hominid features leading to the belief that
around 3-4 mya, man-like primates walked in Eastern
Africa.
The human evolution took place as follows
Å
Human
Ancestors
Time of Origin
Dryopithecus
20-25 mya
Ape-like, hairy, ate soft fruits and
leaves. Arms and legs of same
length, large brain.
Ramapithecus
14-15 mya
More man-like, walked more erect,
teeth-like modern man.
Australopithecus 2 mya
(The first ape man)
General Feature
Probably lived in East African
grasslands and ate fruits, hunted
with stones, weapons, brain capacity
was 400-600 cc.
Homo habilis
(Handy man)
1.2-1.5 mya
Fossils found in East Africa , first
hominid, i.e. human-being like, brain
capacity 650-800 cc, did not eat meat.
Homo erectus
(Java man)
1.5 mya
Fossils found in Java in 1891, brain
capacity 900 cc, probably ate meat.
Homo sapiens
sapiens
neanderthalensis
(Primitive man)
1,00,000-40,000 Known as neanderthal man. Fossils
years ago
found in East and Central Asia, brain
size 1400 cc, used hides to protect
body, buried their dead body. They
became extinct 25,000 years ago.
Homo sapiens
sapiens
(Modern man)
75,000-10,000
years ago
(ice age)
Arose in Africa, developed cave art
around 18,000 years ago, agriculture
started around 10,000 years back and
thus human settlement and
civilisation started.
KEY NOTES
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CHAPTER 07 > Evolution
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1
~ Origin of Life and Evolution of Life Forms
1 Evolutionary biology is
(a)
(b)
(c)
(d)
the study of history of life forms on earth
study of pedigrees of life forms on earth
equivalent to demography
equivalent to anthropology
2 According to one of the most widely accepted
theories, earth’s atmosphere before origin of life
consisted of a mixture of
(a)
(b)
(c)
(d)
O3 , CH4 , O2 and H2 O
O3 , NH3 , CH4 and H2 O
H2 , CO2 , NH3 and CH4
CH4 , NH3 , H2 and H2 O vapours
3 Which theory arguments that life on earth came from
outer space through spores?
(a)
(b)
(c)
(d)
Theory of panspermia
Cosmozoic theory
Spore theory
More than one option are correct
4 For a long time, it was believed that life came out of
decaying and rotting matter like straw, mud, etc. This
was the theory of
(a) catastrophism
(c) panspermia
(b) spontaneous generation
(d) chemogeny
5 Who discarded the theory of spontaneous generation
once and for all?
(a) Louis Pasteur
(c) Spallanzani
(b) Francesco Redi
(d) Aristotle
6 Who showed that life did not evolve from killed yeast
in pre-sterilised flasks?
(a) Oparin
(c) Louis Pasteur
following mixtures in his experiment
(a)
(b)
(c)
(d)
CH4 , NH3 , H2 and water vapours at 800ºC
H2 , O2 , N2 and water vapours at 200ºC
H2 , O2 , C2 and water vapours at 2000ºC
CH4 , NH3 , O2 and water vapours at 500ºC
10 What did Miller obtained from his experiment?
(a) Amino acids
(c) Nitrogen bases
(b) Organic compounds
(d) All of these
11 On early earth, organic acids were produced by the
combination of H 2 with
(a) ammonia and methane (b) hydrogen
(c) organic matter
(d) sulphates and nitrates
12 The first non-cellular forms of life that originated
3 billion years back was/were
(a) protein
(c) RNA
(b) polysaccharide
(d) All of these
13 The first single cell-like structure initially appeared in
(a) air
(b) mountain (c) ocean
(d) soil
14 The sequence of origin of life may be
(a) Inorganic materials → Organic materials → Colloidal
aggregate → Eobiont → Cell
(b) Organic materials → Inorganic materials → Colloidal
aggregate → Eobiont → Cell
(c) Inorganic materials → Organic materials → Eobiont
→ Cell → Colloidal aggregate
(d) Organic materials → Inorganic materials → Eobiont
→ Cell → Colloidal aggregate
15 The given diagram represents Miller’s experiment.
(b) Haldane
(d) Miller
7 Who proposed that the first form of life could have
come from pre-existing non-living organic molecules
and it precedes chemical evolution?
(a)
(b)
(c)
(d)
9 Miller synthesised simple amino acids from one of the
Choose the correct combination of labelling for
A, B, C and D.
A
B
SL Miller
Oparin and Haldane
Charles Darwin
Alfred Wallace
Mixture
of
gases
C
8 Experimental evidence of chemical evolution was
given by
(a) Miller
(c) Oparin
(b) Haldane
(d) All of these
D
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(a) A–Electrodes, B –NH3 + H2 + H2 O + CH4 ,
C–Condensor, D–U-trap
(b) A–Electrodes, B–NH4 + H2 + CO2 + CH3 ,
C–Vacuum pump, D–U-trap
(c) A–Electrodes, B–NH3 + H2 O, C–Condensor,
D–Vacuum pump
(d) A–Electrodes, B–NH3 + H2 + H2 O + CH4 ,
C–Boiling water, D–Vaccum pump
16 What was the name of the sail ship used by Charles
Darwin during his sea voyage?
(a) HMS Beagle
(c) HMS Eagle
(b) HSM Beagle
(d) HSM Eagle
17 According to Charles Darwin’s observations
(a) existing life forms share similarities to the life forms
that existed million of years ago
(b) life forms evolve gradually
(c) any population has built in variations which enable
them to survive in natural conditions
(d) All of the above
18 According to Darwin, those who are better fit in an
environment,
(a)
(b)
(c)
(d)
leave more progeny than others
leave less progeny than others
are eradicated rapidly due to competition
None of the above
19 Theory of natural selection as the mechanism of
evolution was given by
(a) Lamarck
(c) Alfred Wallace
(b) Darwin
(d) JBS Haldane
20 Scientist who also came to the similar conclusions
around the same time of Charles Darwin was
(a)
(b)
(c)
(d)
Alfred Wallace
Hugo de Vries
TH Morgan
Oparin and Haldane
21 Malay Archipelago is
(a)
(b)
(c)
(d)
a group of islands visited by Wallace
a research paper on evolution written by Wallace
a research paper on ecology written by Wallace
a group of organism studied by Wallace
22 The conclusions drawn by Darwin and Wallace were
(a) All existing life forms share similarities and common
ancestors
(b) The ancestors of existing life forms were present at
different periods in the history of earth
(c) The geological history of earth correlates with the
biological history of earth
(d) All of the above
TOPIC 2 ~ Evidences of Evolution
23 Evidence that evolution of life forms has indeed taken
27 Embryological support for evolution given by Ernst
place on earth has come from
Haeckel includes the
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
fossil studies (palaeontological evidences)
morphological and comparative anatomical studies
biochemical studies
All of the above
24 Fossils are the remains of
(a)
(b)
(c)
(d)
hard parts of life forms found in rocks
light parts of life forms found in rocks
proteins and bones of life forms found in rocks
fats and proteins of life forms found in rocks
25 A study of fossils in different sedimentary layers
indicates
(a)
(b)
(c)
(d)
physiological period in which they existed
geological period in which they existed
conditions in which they were living
All of the above
26 Fossils are useful in
(a)
(b)
(c)
(d)
studying extinct organisms
studying history of organisms
Both (a) and (b)
None of the above
presence of hair all over the body in adult human
absence of tail bone and presence of wisdom tooth
absence of vestigial gill slits in human’s embryo
presence of row of vestigial gill slits in embryo of all
vertebrates
28 The similarity of bone structure in the forelimbs of
many vertebrates is an example of
(a) convergent evolution
(c) homology
NEET 2018
(b) analogy
(d) adaptive radiation
29 Which one of the following options gives one correct
example each of convergent evolution and divergent
evolution?
CBSE-AIPMT 2012
(a)
Convergent evolution
Divergent evolution
Eyes of Octopus and
mammals
Bones of forelimbs of
vertebrates
(b) Thorns of Bougainvillea and Wings of butterflies and
tendrils of Cucurbita
birds
(c)
Bones of forelimbs of
vertebrates
Wings of butterfly and birds
(d) Thorns of Bougainvillea and Eyes of Octopus and
tendrils of Cucurbita
mammals
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CHAPTER 07 > Evolution
30 In the animals, the same structures developed along
the different directions due to the adaptations to
different needs. This is called
(a) convergent evolution
(c) disruptive evolution
(b) divergent evolution
(d) directional evolution
31 Divergent evolution gives rise to
(a) homologous organs
(c) Both (a) and (b)
(b) analogous organs
(d) None of these
32 Among the following sets of examples for divergent
evolution, select the incorrect option.
(a)
(b)
(c)
(d)
NEET 2018
Brain of bat, man and cheetah
Heart of bat, man and cheetah
Forelimbs of man, bat and cheetah
Eye of Octopus, bat and man
33 What does presence of homologous organs in
different animals indicate?
(a)
(b)
(c)
(d)
Different ancestry
Common ancestry
Independent development
Dependent development
34 Tendrils of Cucurbita and thorns of Bougainvillea are
examples of
(a) vestigial organs
(c) homologous organs
(b) analogous organs
(d) homoplasy
35 Which of the following structures is homologous to
the wing of a bird?
(a) Wing of a moth
(c) Flipper of whale
CBSE-AIPMT 2015
(b) Hindlimb of rabbit
(d) Dorsal fin of a shark
36 Diagram given below indicates
(c) phylogenetic structures and represent divergent
evolution
(d) homologous structures and represent convergent
evolution
38 The eyes of Octopus and eyes of cat show different
patterns of structure, yet they perform similar
function. This is an example of
NEET 2013
(a) homologous organs that have evolved due to convergent
evolution
(b) homologous organs that have evolved due to divergent
evolution
(c) analogous organs that have evolved due to convergent
evolution
(d) analogous organs that have evolved due to divergent
evolution
39 The process by which organisms with different
evolutionary history evolve similar phenotypic
adaptations in response to a common environmental
challenge, is called
NEET 2013
(a) natural selection
(b) convergent evolution
(c) non-random evolution
(d) adaptive radiation
40 Evolutionary convergence is the development of
(a) common set of characters in closely related groups
(b) common set of characters in the group of different
ancestry
(c) random mating
(d) dissimilar characters in the closely related groups
41 Biochemical similarities are based on study of
(a)
(b)
(c)
(d)
similarities in carbohydrates of organisms
similarities in fat (fatty acid) of organisms
similarities in protein and genes of organisms
All of the above
42 Change of lighter coloured variety of peppered moths
Man
Cheetah
Whale
Bat
(Biston betularia) to darker variety in the industrial
era occurred due to
(a)
(b)
(c)
(d)
selection of darker variety for survival
deletion of gene
industrial carbon deposited on the wings
translocation of gene
43 England in 1850s, i.e. before industrialisation set in, it
(a) analogous organs
(c) convergent evolution
(b) homologous organs
(d) All of these
37 The wings of a bird and the wings of an insect are
CBSE-AIPMT 2015
(a) homologous structures and represent divergent
evolution
(b) analogous structures and represent convergent evolution
was observed that there were more white-winged
moths on trees than dark-winged or melanised moths.
However, in the collection carried out from the same
area, but after industrialisation, i.e. in 1920, there
were more dark-winged moths in the same area, i.e.
the proportion was reversed.
Predict the possible reason for such change.
(a)
(b)
(c)
(d)
Natural selection
Artificial selection
Conditional selection
Divergent selection
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46 Industrial melanism is an example of
44 The peppered moth (Biston betularia), the
black-coloured form becomes dominant over the
light-coloured form of moth in England during
industrial revolution. This is an example of
AIIMS 2018
(a) appearance of the darker-coloured individuals due to
very poor sunlight
(b) protective mimicry
(c) inheritance of darker colour character acquired due to
the darker environment
(d) natural selection whereby the darker forms were
selected
45 Natural indicator of industrial pollution is
(a) algae
(b) fungi
(c) lichen
(d) bacteria
CBSE-AIPMT 2015
(a) neo Darwinism
(c) mutation
(b) natural selection
(d) neo Lamarckism
47 Example of anthropogenic evolution is
(a)
(b)
(c)
(d)
selection of resistant microbes to pesticides
antibiotic resistant eukaryotic cells
Industrial melanism is Biston betularia
All of the above
48 Evolution is
(a)
(b)
(c)
(d)
discontinuous process
stochastic process
Both (a) and (b)
non-essential process
TOPIC 3 ~ Adaptive Radiation
49 Development of different functional structures from a
55 When more than one adaptive radiation appeared to
common ancestral form is called
have occurred in an isolated geographical area, it is
(a) differential evolution (b) adaptive radiation
(c) non-adaptive radiation (d) regressive evolution
(a)
(b)
(c)
(d)
50 The process by which different type of finches were
evolved in Galapagos islands is a consequence of
(a)
(b)
(c)
(d)
adaptive radiation
geographic similarity
geographic dissimilarity
adaptive convergence
convergent evolution
divergent evolution
natural selection
genetic drift
56 Identify what is indicated in the given diagram?
51 The original finches from which other finches arose
on Galapagos island were
(a) seed-eating
(c) vegetarian
(b) insectivorous
(d) carnivorous
Common
Ancestor
52 Which one of the following aspects of evolution is
shown by Darwin’s finches?
(a)
(b)
(c)
(d)
Biogeographic evidence
Industrial melanism
Biochemical evidence
Embryological evidence
53 The diversity in the type of finches and adaptation to
different feeding habits on the Galapagos islands, as
observed by Darwin, provides an evidence of
(a)
(b)
(c)
(d)
origin of species by natural selection
intraspecific variation
intraspecific competition
interspecific competition
54 Australian marsupials are the example of
(a)
(b)
(c)
(d)
homologous radiation
analogous radiation
adaptive radiation
convergent radiation
I.
II.
III.
IV.
Recombination
Adaptive radiation
Ecological succession
Different species of penguins by mutation
Choose the correct option.
(a)
(b)
(c)
(d)
Only I
Only III
Only IV
Only II
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CHAPTER 07 > Evolution
57 Identify what the given diagram indicates?
adaptive radiation?
Tasmanian wolf
Koala bear
Australian
Marsupials
Marsupial rat
Kangaroo
(a)
(b)
(c)
(d)
Convergent evolution
Divergent evolution
Recapitulation
Parallel evolution
58 The classical example of adaptive radiation in
development of new species is
(a)
(b)
(c)
(d)
Darwin’s finches
marsupials of Australia
locomotion in mammals
All of the above
59 Example of convergent evolution is
(a)
(b)
(c)
(d)
60 Which of the following is not an examples of
Darwin finches and marsupial mouse
Placental wolf and Tasmanian wolf
Placental wolf and Darwin finches
Tasmanian wolf and marsupial mole
(a)
(b)
(c)
(d)
Wombat, numbat, flying phalanger
Darwin’s finches
Different mammals in other parts of world
Lemur and spotted cuscus
61 In Australia, marsupials and placental mammals have
evolved to share many similar characteristics. This
type of evolution may be referred to as
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(a)
(b)
(c)
(d)
adaptive radiation
divergent evolution
cyclical evolution
convergent evolution
62 A population of a species invades a new area. Which
of the following conditions will lead to adaptive
radiation?
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(a) Area with large number of habitats having very low
food supply
(b) Area with a single type of vacant habitat
(c) Area with many types of vacant habitats
(d) Area with many habitats occupied by a large number of
species
TOPIC 4 ~ Biological Evolution and its Mechanism
63 What is meant by the term ‘Darwin fitness’?
(a)
(b)
(c)
(d)
Ability to survive and reproduce
High aggressiveness
Healthy appearance
Physical strength
64 Survival of the fittest is possible due to the
(a)
(b)
(c)
(d)
overproduction
favourable variations
environmental changes
inheritance of acquired characters
65 Darwinian fitness can be estimated by
(a) how long different individual in a population survive
(b) number of offspring produced by different individuals
in population
(c) individual have a large size in population
(d) species recover after mass extinction
66 Which of the following are the two key concepts of
Darwinian theory of evolution?
(a)
(b)
(c)
(d)
Genetic drift and mutation
Adaptive radiation and homology
Mutation and natural selection
Branching descent and natural selection
67 Which concept was not included in Charles Darwin’s
theory of natural selection?
(a)
(b)
(c)
(d)
Survival of the fittest
Struggle for existence
Overproduction of offspring
Punctuated equilibrium
68 What is the difference between natural selection and
sexual selection?
(a)
(b)
(c)
(d)
Sexual selection occurs during sexual intercourse
Natural selection is a type of sexual selection
Sexual selection is an example of natural selection
Sexual selection occurs within demes
69 Which of the following situations would most likely
result in the highest rate of natural selection?
(a)
(b)
(c)
(d)
Reproduction by asexual method
Low mutation is an stable environment
Little competition
Reproduction by sexual method
70 According to Darwin, the organic evolution is due to the
(a)
(b)
(c)
(d)
intraspecific competition
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interspecific competition
competition within closely related species
reduced feeding efficiency in one species due to the
presence of interfering species
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Master The NCERT > Biology (Vol-II)
170
71 Which one of the following was not explained by
76 Which of the following differences between
Darwinism?
Lamarckism and Darwinism is incorrect?
(a)
(b)
(c)
(d)
Lamarckism
Darwinism
(a)
It does not consider struggle
for existence
Struggle for existence is
very important in this theory
(b)
Only useful variations are
transferred to the next
generation
All the acquired characters
are inherited to the next
generation.
(c)
Neglects survival of the
fittest
Based on survival of the
fittest
(d)
None of the above
Natural selection
Struggle for existence
Arrival of the fittest
Origin of species
72 Which of the following factors was not taken into
account by Darwin in his theory of natural selection?
(a)
(b)
(c)
(d)
Struggle for existence
Discontinuous variations
Parasites and predators as natural enemies
Survival of the fittest
73 Lamarck’s theory of evolution is also known as
(a)
(b)
(c)
(d)
theory of use and disuse of organs
theory of genetic characters
theory of spontaneous characters
theory of impose characters
74 Who proposed that long neck of giraffes evolved due
to foraging of leaves on tall trees?
(a)
(b)
(c)
(d)
Lamarck
Darwin
Malthus
Aristotle
75 What was the Lamarck’s explanation for long necked
giraffes?
(a)
(b)
(c)
(d)
Stretching of necks over many generations
Short neck suddenly changed into long one
Natural selection
Mutation
77 Hugo de Vries put forth his idea of mutation by his
work on
(a) pea plant
(c) evening primrose
(b) Drosophila
(d) maize plant
78 Who proposed the concept of saltation?
(a) Darwin
(c) de Vries
(b) Mendel
(d) Thomas Malthus
79 What does the term ‘Saltation’ imply?
(a)
(b)
(c)
(d)
Excess of species at a given area
Reduced number of species due to saline environment
Occurrence of variations gradually, step by step
Single step large mutations
80 Variations caused by mutation, as proposed by Hugo
de Vries are
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(a) random and directionless
(b) small and directional
(c) small and directionless
(d) random and directional
TOPIC 5 ~ Hardy-Weinberg Principle
81 Hardy-Weinberg principle is the
(a)
(b)
(c)
(d)
stable allele frequency in a population
genetic structure of an evolving population
varying allele frequency in a population
phenotypic structure of a non-evolving population
82 Genetic equilibrium refers to the phenomenon in which
(a)
(b)
(c)
(d)
the trait remains constant in a population
the total genes remain constant in a population
the total genes keeps on varying in a population
traits keeps on varying in a population
83 Change in gene frequency of a population means
(a)
(b)
(c)
(d)
evolution is in progress
Hardy-Weinberg equilibrium is not achieved
there may be a selection, migration or mutation
All of the above
84 Hardy-Weinberg principle can be expressed as
(a) p 2 − 2 pq − q 2 = 1
(b) p 2 + 2 pq + q 2 ≥ 1
(c) p 2 + 2 pq + q 2 ≤ 1
(d) p 2 + 2 pq + q 2 = 1
85 A gene locus has two alleles A, a. If the frequency of
dominant allele A is 0.4, then what will be the
frequency of homozygous dominant, heterozygous
and homozygous recessive individuals in the
population?
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(a) 0.16(AA); 0.24(Aa); 0.36(aa)
(b) 0.16(AA); 0.48(Aa); 0.36(aa)
(c) 0.16(AA); 0.36(Aa); 0.48(aa)
(d) 0.36(AA); 0.48(Aa); 0.16(aa)
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CHAPTER 07 > Evolution
86 Which of the following conditions represents the
extent of evolutionary change in Hardy-Weinberg
principle?
93 Name the type of natural selection depicted in the given
diagram (type I, type II and type III).
Type I
(a) Value of ( p + q )2
(b) Difference between measured value and expected
value
(c) Sum of measured value and expected value
(d) This principle cannot predict the extent of
evolutionary change
(d) q 2
e
at
in
im
El
Mean
Conserved
by selection
Eliminated
CBSE-AIPMT 2015
(c) pq
Conserved
d
Eliminated
heterozygous individual is represented by
(b) 2 pq
Mean
Conserved
87 In Hardy-Weinberg equation, the frequency of
(a) p 2
Type II
Mean
Mean
Eliminated
88 The tendency of population to remain in genetic
equilibrium may be disturbed by
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(a) random mating
(b) lack of migration
(c) lack of mutations
(d) lack of random mating
Type III
Mean
Conserved
89 Identify the phenomenon in which a new set of
Eliminated
population is formed from the set of existing
population due to the random excessive change in
the allele frequency.
(a) Founder effect
(c) Bottle-neck effect
(b) Genetic drift
(d) All of these
90 Genetic drift operates in
(a)
(b)
(c)
(d)
Eliminated
Mean
Mean
Conserved
CBSE-AIPMT 2015
small isolated population
large isolated population
non-reproductive population
slow reproductive population
91 ‘XX’ is a type of selection process in evolution
that promotes population changes in one particular
direction. ‘XX’ favours small or large sized
individuals mean size of population changes.
Identify ‘XX’.
(a)
(b)
(c)
(d)
Stabilising selection
Directional selection
Disruptive selection
None of the above
Type I
Disruptive
Directional
Stabilising
Stabilising
Type II
Directional
Disruptive
Directional
Disruptive
Type III
Stabilising
Stabilising
Disruptive
Directional
94 Artificial selection to obtain cows yielding high milk
output represents
92 ‘PP’ is a type of selection that favours both small
sized and large-sized individuals. ‘PP’ eliminates
most of the members with mean expression, so as
to produce two peaks in the distribution of the
tract that many leads to the development of two
different populations. Identify ‘PP’.
(a) Disruptive selection
(c) Directional selection
(a)
(b)
(c)
(d)
(b) Stabilising selection
(d) None of these
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(a) stabilising selection as it stabilises this character in the
population
(b) directional as it pushes the mean of the character in one
direction
(c) disruptive as it splits the population into two, one yielding
higher output and the other lower output
(d) stabilising followed by disruptive as stabilises the
population of produce higher yielding cows
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Master The NCERT > Biology (Vol-II)
172
95 In a large randomly mating population, only one
person in 10,000 is an albino. What will be the
frequency of carrier person of albinism?
(a) 1 in 100
(b) 99 in 10,000
(c) 2 in 10,000
(d) 1 in 50
96 Allopatric speciation occurs when
(a) genetically related populations inhabit widely separated
geographical area
(b) genetically unrelated populations inhabit widely
separated geographical area
(c) genetically related populations inhabit the same
geographical area
(d) genetically unrelated populations inhabit the same
geographical area
TOPIC 6 ~ A Brief Account of Evolution
97 Choose the incorrect pair.
(a) Invertebrates were formed and active – By 500 mya
(b) Seaweeds existed – Around 320 mya
(c) First organisms that invaded land – Single-celled
animals
(d) Fish with stout and strong fins – Around 350 mya
98 Name the animal that evolved into the first probable
amphibians and lived on both land and water.
(a) Whale
(c) Amphioxus
(b) Coelacanth (lobefins)
(d) Balanoglossus
99 There was no life in
(a) Cenozoic era
(c) Palaeozoic era
(b) Mesozoic era
(d) Azoic era
100 Which period in geological time scale is considered
the golden era of fish?
(a) Mississippian
(c) Devonian
Jurassic period. This period was also marked for the
evolution of higher insects and angiosperms, conifers,
cycads, etc. Jurassic period belongs to which era?
(b) Palaeozoic
(d) Proterozoic
102 During which period did the first seed plant appear?
(a) Silurian
(c) Carboniferous
(b) Devonian
(d) Cretaceous
103 The Cenozoic era is often designated as
(a) age of fish
(c) age of mammals
(a) Mesozoic
(c) Palaeozoic
(b) age of reptiles
(d) age of amphibians
(a)
(b)
(c)
(d)
Palaeozoic → Archaeozoic → Cenozoic
Archaeozoic → Palaeozoic → Proterozoic
Palaeozoic → Mesozoic → Cenozoic
Mesozoic → Archaeozoic → Proterozoic
109 First dinosaurs and first egg-laying mammals
originated in
(a) Jurassic period
(c) Permian period
(b) Azoic era
(d) Mesozoic era
given diagram.
Lizards
Turtles
Quaternary
(b) Equus
(d) Columba
106 Mesozoic era is called the age of
(a) fishes
(c) reptiles
(b) amphibians
(d) birds
Birds
Tuataras
Crocodiles
Snakes
Mammals
0
50
...C...
Dinosaurs
(extinct)
Cretaceous 100
...B...
150
Triassic
200
Therapsids
(extinct)
Thecodonts
(extinct)
...A...
250
Pelycosaurs
(extinct)
Sauropsids
Synapsids
Carboniferous 300
350
105 Which of the following is an extinct animal?
(a) Protopterus
(c) Archaeopteryx
(b) Triassic period
(d) Cambrian period
110 Identify the geographical periods ( A, B , C ) in the
104 In which era Protozoa, sponge and algae originate?
(a) Cenozoic era
(c) Proterozoic era
(b) Cenozoic
(d) Proterozoic
108 The correct order of evolutionary scale is
(b) Silurian
(d) Jurassic
101 Giant dinosaurs and reptiles predominated during the
(a) Cenozoic
(c) Mesozoic
107 The most recent era in geological time scale is
Early reptiles
(extinct)
(a)
(b)
(c)
(d)
A–Tertiary, B–Jurassic, C–Permian
A–Tertiary, B–Permian, C–Jurassic
A–Permian, B–Jurassic, C–Tertiary
A–Jurassic, B–Tertiary, C–Permian
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CHAPTER 07 > Evolution
111 Choose the incorrectly matched pair.
(a)
(b)
(c)
(d)
113 In which epoch, only modern humans prevail?
Reptiles — Thick-shelled eggs which do not dry up
Tyrannosaurus rex — Fish like reptile
Dinosaurs — May be evolved into birds
Continental drift — South America joined
North-America
112 The first viviparous mammals whose fossils are
small-sized were like
(a) shrews
(b) monkeys
(c) rats
(d) lobefins
(a) Pleiostocene (b) Holocene (c) Pliocene (d) Miocene
114 Which phenomena confined the pouched mammals to
Australia they survived because of lack of
competition from any other mammals?
(a)
(b)
(c)
(d)
Continental origination
Continental shifting
Continental drift
Continental evolution
TOPIC 7 ~ Origin and Evolution of Man
122 Who was more intelligent than modern man,
115 Choose the incorrect pair.
(a) Ramapithecus – Man-like
(b) Dryopithecus – Ape-like
(c) Fossil of man-like bones were discovered
– Ethopia and Tanzania
(d) Australopithecus – Probably lived in Western
Africa desert
cave-dweller, had prominent chin and appeared after
neanderthal man?
(a) Erect man
(c) Hominid tool maker
(b) Cro-Magnon man
(d) First ape man
123 What was the most significant trend in the evolution
of modern man (Homo sapiens) from his ancestors?
116 First human like hominid is known as
(a) Neanderthal man
(c) Dryopithecus
(b) Homo habilis
(d) Homo erectus
117 Brain (cranial) capacity of Homo habilis was
(a) 750-850 cc
(c) 650-800 cc
(b) 750-800 cc
(d) 550-700 cc
118 The fossil finding suggest that closest fossil to Homo
habilis was
(a) Homo erectus
(c) Dryopithecus
(b) Homo sapiens
(d) Neanderthal man
119 The extinct human who lived 10,00,00 to 40,000
years ago, in Europe, Asia and parts of Africa, with
short stature, heavy eyebrows, retreating fore heads,
large jaws with heavy teeth, stocky bodies, a
lumbering gait and stooped posture was
CBSE-AIPMT 2012
(a) Homo habilis
(b) Neanderthal human
(c) Cro-Magnon human
(d) Ramapithecus
120 Homo sapiens, neanderthalensis and Cro-Magnon
man, probably originated from
(a) Homo erectus
(c) Ramapithecus
(b) Homo habilis
(d) Proconsul
121 The difference between Homo sapiens and Homo
erectus was
(a) Homo sapiens originated in Africa, while Homo erectus
originated in Asia
(b) Homo erectus were much smaller in size than Homo
sapiens
(c) Homo erectus stayed in Africa, while Homo sapiens did
not
(d) the size of the brain of Homo erectus was smaller than
that of Homo sapiens
CBSE-AIPMT 2011, 12
(a) Shortening of jaws
(b) Binocular vision
(c) Increasing brain capacity (d) Upright posture
124 Who used hides to protect their body and buried their
dead?
(a) Neanderthal man
(c) Australopithecus
(b) Homo habilis
(d) Dryopithecus
125 Homo sapiens most likely arose in
(a) India
(b) America (c) England
(d) Africa
126 Homo sapiens arose during
(a)
(b)
(c)
(d)
ice age between 75000-10000 years ago
continental drift between 75000-10000 years ago
continental drift between 75000-5000 years ago
ice age between 50000-10000 years ago
127 The chronological order of human evolution from
early to the recent stages is
(a) Ramapithecus → Australopithecus → Homo habilis →
Homo erectus
(b) Australopithecus → Ramapithecus → Homo habilis →
Homo erectus
(c) Pithecanthropus pekinensis → Homo habilis → Homo
erectus
(d) Australopithecus → Ramapithecus → Pithecanthropus
pekinensis → Homo erectus
128 The diagram given here shows the skull of two
different mammals. Choose the most appropriate
difference between A and B.
A
(a)
(b)
(c)
(d)
B
Skull A has more teeth than skull B
Skull A has more brain capacity than skull B
Skull A is of a human and skull B is of an ape
Skull A is of an ape and skull B is of human
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SPECIAL TYPES QUESTIONS
I. Assertion and Reason
■ Direction (Q. No. 129-143) In each of the following
questions, a statement of Assertion (A) is given followed
by corresponding statement of Reason(R).
Of the statements, mark the correct answer as
(a) If both A and R are true and R is the correct
explanation of A
(b) If both A and R are true, but R is not the correct
explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true
129 Assertion (A) Theory of chemical evolution
130
131
132
133
134
135
proposed that life came from pre-existing non-living
organic molecules.
Reason (R) Primitive earth conditions led to the
production of organic molecules.
Assertion (A) The theory of special creation states
that God created life by his divine act of creation.
Reason (R) Louis Pasteur rejected the theory of
spontaneous generation.
Assertion (A) Earth is about 15 billion years old.
Reason (R) Life appeared 500 million back after the
formation of earth.
Assertion (A) Earliest organisms that appeared on
the Earth were non-green and presumably
anaerobes.
Reason (R) The first autotrophic organisms were the
chemoautotrophs that never released oxygen.
Assertion (A) Microspheres were aggregates of
organic biomolecules surrounded by film of water
molecule.
Reason (R) Coacervates lack definite membrane,
but do exhibit some life like characters.
Assertion (A) Ernst Haeckel supported the
embryological similarities as an evidence of
evolution.
Reason (R) The embryos of all vertebrates including
humans develop a row of vestigial gill slits which
are absent in adult vertebrates.
Assertion (A) Natural selection is an outcome of the
differences in survival and reproduction among
individuals that show variations in one or more
traits.
136
137
138
139
Reason (R) Adaptive forms of a given trait tend to
become more common. Less adaptive ones becomes
less common or disappear.
Assertion (A) Whales and mammals share similarities
in the pattern of bones of forelimbs.
Reason (R) These organisms suggest occurrence of
divergent evolution.
Assertion (A) Analogous structures are different in
appearance and have same function.
Reason (R) Divergent evolution leads to analogy.
Assertion (A) Lichens act as pollution indicators.
Reason (R) These do not grow in areas that are polluted.
Assertion (A) Lichens are symbiotic relationships of
algae and viruses.
Reason (R) These are sensitive to SO 2 levels in the air.
140 Assertion (A) Hugo de Vries said mutations cause
speciation.
Reason (R) Mutations are slow changes.
141 Assertion (A) The introduction of new alleles into the
local gene pool by interbreeding of migrating
individuals with members of local population is called
gene migration.
Reason (R) If gene migration happens multiple times,
it is called gene recombination.
142 Assertion (A) Sudden inheritable changes take place
in genome of an organism due to certain factors called
mutations.
Reason (R) Lamarck’s theory of evolution is popularly
called the theory of continuity of germplasm.
143 Assertion (A) Among the primates, chimpanzee is the
closest relative of the present day humans.
Reason (R) The banding pattern in the autosome number
3 and 6 of man and chimpanzee is remarkably similar.
II. Statement Based Questions
144 Which of the following statements about orgin of life is
incorrect?
(a) The universe is almost 20 billion years old
(b) Big Bang theory explained that universe originated by a
huge explosion
(c) Present day galaxies are formed by the condensation of
hydrogen and helium under gravitational pull
(d) None of the above
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CHAPTER 07 > Evolution
145 Identify the correct statement.
(a) Earth was formed about 4.5 billion years ago
(b) Early earth had no atmosphere
(c) The temperature of universe came down due to its
expansion
(d) All of the above
146 Which one of the following statements is true
regarding the theory of natural selection?
(a)
(b)
(c)
(d)
It was the first theory of organic evolution
It does explain information derived from fossils
It has failed to explain the origin of variations
It has succesfully explained concept of speciation
147 Which of the following statements would Darwinism
most likely disagree with?
(a) Individuals within a population vary in the
characteristics they possess
(b) Evolution is best viewed as a purpose less and nondirectional change over time
(c) Natural selection is the mechanism by which biological
evolution takes place
(d) The fossil record supports the view that biological
evolution has occurred
148 Identify the incorrect statement.
(a) In natural selection, heritable variations enable better
survival
(b) Variations due to gene flow changes allele frequency in
future generation
(c) Gene flow occurs due to multiple gene migration
(d) None of the above
149 Which one of the following statements is/are correct
about Australopithecus?
(a)
(b)
(c)
(d)
They essentially ate fruits
They hunted with stone weapons
They were transitional stage between ape and humans
All of the above
150 Which of the following is the correct sequence of
events in the origin of life?
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I. Formation of protobionts.
II. Synthesis of organic monomers.
III. Synthesis of organic polymers.
IV. Formation of DNA-based genetic systems.
Choose the correct option.
(a) I, II, III and IV
(c) II, III, I and IV
(b) I, III, II and IV
(d) II, III, IV and I
151 Which of the following statements are correct about
the characteristics of protobionts, like microspheres as
envisaged in the abiogenic origin of life?
I. They were able to reproduce.
II. They could separate the combinations of molecules
from the surroundings.
III. They were partially isolated from the surroundings.
IV. They could maintain an internal environment
absolutely.
Choose the correct option.
(a) I and II
(c) III and IV
(b) II and III
(d) I, II, III and IV
152 Which of the following statements stands in favour of
abiogenesis?
I. Spontaneous generation.
II. Origin of viruses and microbes.
III. Origin of life from living organisms.
IV. Origin of life from non-living matter.
The correct statement(s) is/are
(a) I and II
(c) III and IV
(b) II and III
(d) Only IV
153 Which of the following statements are the correct pair
of homologous organs?
I. Hands of man and wings of bat.
II. Wings of bat and wings of cockroach.
III. Wings of bird and wings of butterfly.
IV. Fins of fish and forelimbs of horse.
V. Forearm of human and forelimbs of horse.
Choose the correct option
(a) I and II
(b) I and V
(c) III and IV (d) IV and V
154 Which of the following statements are correct?
I. Wings of insects and birds are homologous organ.
II. Wings of bats and birds are homologous organ.
III. Wings of insects and bats are analogous.
IV. Wings of insects and birds are analogous.
Choose the correct option.
(a) I and II
(c) I and IV
(b) I and III
(d) II, III and IV
155 Select the incorrect statements.
I. Natural selection is essential for evolution.
II. Natural selection does not include variations.
III. Concept of natural selection was given by Hugo de
Vries.
IV. Mutation is a sudden inheritable change.
V. Synthetic theory is also called Neo-Darwinism theory
of evolution.
The correct combination is
(a) I, II and III
(c) III, IV and V
(b) II, III and IV
(d) II and III
156 Which of the following statements are correct?
I. Survival of the fittest is based upon the characteristics
that are inherited.
II. Darwin’s variations are small and directional.
III. The fitness is the end result of the ability to adapt.
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Master The NCERT > Biology (Vol-II)
176
IV. Genetic drift is operate in small populations.
V. Genetic drift operates in large populations.
VI. Presence of genetic drift upsets the Hardy-Weinberg
equilibrium.
Choose the correct option.
(a) I, II, III and IV
(c) I, II, III, V and VI
(b) IV, V, VI and II
(d) I, II, III, IV and VI
157 True statements regarding the genetic drift is/are
I. It mostly occurs in smaller populations.
II. Certain alleles can be lost forever because of genetic
drift.
III. Founder effects and bottle neck effects are caused by
genetic drift.
IV. Mutations are primarily responsible for genetic drift.
The correct combination showing true statements is
(a) Only I
(c) II and IV
(b) III and IV
(d) All except IV
158 Which of the following statements regarding the
evolution of plants and animals are correct?
I. Amphibians evolved into reptiles.
II. Fish with stout and strong fins could move on land and
go back to water. This was about 350 million years ago.
III. Giant ferns fell to form coal deposits slowly.
IV. About 65 million years ago dinosaurs died out.
V. Archaeopteryx is the connecting link between birds
and reptiles.
The correct combination is
(a) I and II
(c) V and I
(b) III and IV
(d) I, II, III, IV and V
159 Mark the correct statements.
I. Karl Ernst von Baer noted that embryo never pass
through adult stages of other animals and thus
discarded Ernst Haeckel’s embryological support for
evolution.
II. Homology in vertebrate brain indicates common
ancestry.
III. Theory of acquired character was given by de Vries.
IV. After industrialisation, the white moth population
decreased due to predators.
The correct option is
(a) I, II and III
(c) II, III and IV
(b) I, III and IV
(d) I, II and IV
160 Choose the incorrect statements.
I. The essence of Darwinian theory about evolution can
be seen in the phenomenon of natural selection.
II. The rate of appearance of new forms is not linked to the
evolution.
III. Adaptive ability is a complete evolution.
IV. Mutations are random and directionless.
Choose the correct option.
(a) I and II
(c) I and III
(b) II and III
(d) I and IV
161 When a species gets separated geographically, it
evolves separately? Which of the following
conditions would determine whether they are now
different species?
I. They fail to interbreed.
II. They failed to give fertile offspring.
III. They have different coloured body.
IV. They appear morphologically slightly different.
Choose the correct combination from given options.
(a) I and II
(c) III and IV
(b) II and III
(d) I and IV
162 Choose the correct statements with reference to
organic evolution.
AIIMS 2018
I. Flippers of whale and wings of bat exhibit analogy.
II. Wings of butterfly and wings of bird exhibit
homology.
III. Organs with dissimilar structure are called analogous
organs.
IV. Organs with similar structure and origin are called
homologous organs.
(a) I and IV
(c) III and IV
(b) I and III
(d) II and IV
163 Which of the following statements is correct
regarding the evolution of humans?
I. The skull of adult chimpanzee is more like adult human
skull than baby chimpanzee skull.
II. The skull of baby chimpanzee is more like adult human
than adult chimpanzee skull.
III. Dryopithecus is oldest human like fossil.
IV. Dryopithecus was found in Miocene rock of Africa and
Europe.
The correct option is
(a) I and II
(b) I and III
(c) I and IV (d) II, III and IV
164 Consider the following statements.
I. Darwin asserted that heritable variations and better
resource utilisation enable an individual to reproduce
efficiently.
II. Darwinian variations were small and directional select
the correct option.
(a) I is true, II is false
(c) Both I and II are true
(b) I is false, II is true
(d) Both I and II are false
165 In his theory of evolution, Lamarck explained
I. Internal vital force.
II. Effect of environment on organisms.
III. Inheritance of acquired characters.
IV. Use and disuse of organs.
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177
CHAPTER 07 > Evolution
Choose the correct combination.
(a) I and II
(c) I, II and IV
(b) II and III
(d) I, II, III and IV
166 Which of the following phenomena support the
Darwin’s concept of natural selection in organic
evolution?
I. Development of transgenic animals.
II. Production of Dolly.
III. Increased prevalance of pesticides has led to pesticide
resistance in insects.
IV. Industrial melanism.
Choose the correct statement.
(a) I and II
(b) II and III (c) III and IV (d) I and IV
167 Lamarck’s concept of inheritance of acquired
characters was discarded by
I. Mendel’s laws of inheritance.
II. Theory of natural selection.
III. Mutational theory.
IV. Theory of continuity of germplasm.
Choose the correct combination of the given options
to complete the given statement.
(a) I and II
(b) II and III (c) I and IV (d) III and IV
168 Which of the following features are connected with
the modern theory of evolution?
I. Genetic and chromosomal mutation.
II. Genetic recombination and natural selection.
III. Reproductive isolation.
The correct combination is
(a) I and II
(c) I and III
(b) II and III
(d) I, II and III
169 Which of the following statements correctly defines
the phenomenon of genetic drift?
I. It is random change in gene allele frequency.
II. It occurs by chance.
III. It is directional.
IV. It causes elimination of certain alleles.
V. It causes fixation of alleles.
The correct combination is
(a) I, II and III
(c) I, III and V
(b) III, IV and V
(d) I, II, IV and V
170 Consider the following statements.
I. Evolution by natural selection have started when
cellular forms of life with differences in metabolic
capability originated on earth.
II. The essence of Darwinian theory about evolution is
natural selection.
Select the correct option.
(a) I is true, II is false
(c) I is false, II is true
(b) Both I and II are true
(d) Both I and II are false
171 Consider the following statements.
I. Microbes are able to grow on new nutrient media due
to natural selection.
II. Adaptive ability is inherited and has genetic basis.
Select the correct option.
(a) Both I and II are true
(c) Both I and II are false
(b) I is true, II is false
(d) I is false, II is true
172 Natural selection
I. tends to decrease the survival and reproduction of an
organism.
II. acts on organism phenotype.
III. mechanism of evolution explained by Darwin.
Which of the following statements are correct?
(a) I, II and III
(c) II and III
(b) I and II
(d) I and III
173 Evidence which favours the theory of acquired
characters are
I. the absence of limbs in snakes.
II. the presence of webbed toes in aquatic bird.
III. lack of pigments in cave dwelling animals.
IV. Darwin finches.
V. melanisation peppered moths.
Choose the correct option.
(a) I and II
(c) I, II and IV
(b) II and III
(d) I, II and III
174 Consider the following statements and choose the
correct statements.
I. Gene mutations are directional changes in the bases of
sequences of genes.
II. Bottle neck effect is the fluctuation in population
density causing reshuffling of some of the genes in a
gene pool in random fashion.
III. Founder effect is called as Sewall Wright effect.
IV. Modern concept of evolution is also called synthetic
theory of evolution.
(a) II and IV (b) I and III (c) I and II
(d) III and IV
175 Consider the following statements.
I. Pre-historic cave art was developed earlier than
agriculture.
II. Human history of growth is proportional to decline of
civilisations.
Select the correct option.
(a) Both I and II are true
(c) Both I and II are false
(b) I is true, II is false
(d) I is false, II is true
176 Consider the following statements.
I. Fossils discovered in Ethiopia and Tanzania revealed
hominid features. Reflecting that about 3-4 mya man
like primates walked in Eastern Africa.
II. Home erectus fossils were discovered in Java in 1891.
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Master The NCERT > Biology (Vol-II)
178
Select the correct option.
(a) I is true, II is false
(c) I is false, II is true
(b) Both I and II are true
(d) Both I and II are false
177 Find out the incorrect statements about Homo habilis.
I. Also called able or skilful man.
II. Also called tool maker.
III. Fossil discovered from East Africa.
IV. 500 cc was its cranial capacity.
V. Have teeth like modern man.
VI. Lived nearly 2 million years ago.
Codes
A
(a) 1
(b) 3
(c) 3
(d) 4
B
2
4
4
3
C
3
1
2
2
D
4
2
1
1
181 Match the following columns.
Column I
Column II
A. Analogous organs
1. Ontogeny repeat phylogeny
B. Miller and Urey
2. Experiment (chemical
evolution)
C. Oparin and Haldane
3. Chemical evolution (theory)
The correct option is
(a) IV and V
(c) II, III and VI
(b) Only IV
(d) I, II, III, IV and VI
178 Consider the following statements.
I. Australopithecus africanus had brain capacity about
500 cc similar to that of ape.
II. Erect man or Homo erectus is skull was flatter than that
of modern man.
III. Cro-Magnon man had a slightly prognathous face.
IV. Neanderthal man is regarded as most recent ancestor
of today’s man.
D. Human embryo have gill 4. Wings of bird and butterfly
Codes
A
(a) 4
(b) 4
(c) 1
(d) 4
B
3
2
2
3
C
1
3
3
2
D
2
1
4
1
182 Match the following columns.
Choose the incorrect statements.
(a) III and IV
(b) II and III
(c) I and II
(d) I and III
A.
Genetic drift
1. Change in the population’s allele
frequency due to chance alone
III. Matching Type Questions
B.
Natural selection
2. Difference in survival individuals
C.
Gene flow
3. Immigration or emigration
changes the allele frequency
D.
Mutation
4. Source of the new alleles
Column I
(Terms)
179 Match the hominids with their correct brain size.
NEET 2019
Column II
Column I
A.
Homo habilis
1. 900 cc
B.
Homo neanderthalensis
2. 1350 cc
C.
Homo erectus
3. 650-800 cc
D.
Homo sapiens
4. 1400 cc
Codes
A
(a) 3
(c) 4
Column II
(Explanations)
Codes
A
(a) 1
(c) 1
B
2
4
C
3
2
D
4
3
A
(b) 1
(d) 4
C
1
1
D
4
2
A
(b) 3
(d) 3
B
4
1
C
1
4
180 Match the following columns.
Column I
C
4
1
D
3
3
183 Match the following columns.
Column I
B
2
3
B
2
2
D
2
2
Column II
A. Wallace
1. Natural selection
B.
Malthus
2. Essay of population
C.
Hardy-Weinberg law
D. Industrial melanism
3. Biston betularia
4.
p2 + 2 pq + q2 = 1
Column II
A.
Darwin
1.
Inherited
B.
Genetic drift
2.
Not inherited
C.
Mutation in germ cells
3.
HMS Beagle
D.
Mutation in somatic cells 4.
Founder effect
Codes
A
(a) 1
(b) 1
(c) 1
(d) 2
B
2
2
3
3
C
4
3
4
4
D
3
4
2
1
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179
CHAPTER 07 > Evolution
184 Match the following columns.
Column I
(Scientists)
Column II
(Related to)
A.
Darwin
1.
Natural selection
B.
Lamarck
2.
Inheritance of acquired character
C.
Pasteur
3.
Swan-necked experiment
D.
de Vries
4.
Mutational theory of inheritance
Codes
A
(a) 2
(b) 1
(c) 1
(d) 1
B
3
3
2
2
C
4
4
3
4
Codes
A
(a) 3
(b) 4
(c) 2
(d) 3
D
1
2
4
3
Column I
(Types of natural
selection)
Stabilisation
selection
1.
More individuals acquire value
other than mean character
value
B.
Directional
selection
2.
More individuals acquire mean
character value
C.
Disruption selection 3.
More individuals acquire
peripheral character value at
both ends of distribution curve
187 Match the Column I with Column II. Select the
correct option from the codes given below.
C
2
1
3
2
186 Match the following columns.
Column I
Mesozoic
1.
First amphibians
B.
Devonian
2.
Proliferation of reptiles
C.
Palaeocene
3.
160 million years
D.
Permian
4.
Radiation of primitive
mammals
Codes
A
(a) 1
(b) 3
(c) 4
(d) 2
B
4
1
1
1
C
3
4
2
4
D
2
2
3
3
188 Match the Column I with Column II. Select the
correct option from the codes given below.
Primates
Cranial Capacities
(in cubic centimetres)
A.
Chimpanzee and gorilla
1.
325-510 cc
B.
Australopithecus
2.
500 cc
C.
Homo habilis
3.
700 cc
D.
Java ape man
4.
800-1000 cc
Column II
A. Ichthyosaurus
1. Caught in South Africa in 1938
B.
Coelacanth
2. Fell to form coal deposits
C.
Giant pteridophytes
3. Disappeared about 65 mya
D. Dinosaurs
Column II
(Related to)
A.
Codes
(a)
(b)
(c)
(d)
D
4
3
1
1
Column II
(Explanations)
A.
B
3
2
1
1
C
1
2
4
2
Column I
(Time periods in
geological time scale)
185 Match the following columns.
A
1
3
2
3
B
2
1
3
4
4. Fish-like reptiles in 200 mya
Codes
A
(a) 4
(b) 2
(c) 1
(d) 3
B
3
3
2
2
C
2
4
3
1
D
1
1
4
4
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Master The NCERT > Biology (Vol-II)
180
NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
189 The theory of spontaneous generation stated that
(a)
(b)
(c)
(d)
life arose from living forms only
life can arise from both living and non-living
life can arise from non-living things only
life arises spontaneously, neither from living nor from
the non-living
190 In 1953, SL Miller created primitive earth conditions
197 Appearance of antibiotic-resistant bacteria is an
example of
(a)
(b)
(c)
(d)
adaptive radiation
transduction
pre-existing variation in the population
divergent evolution
198 Match the scientists listed under Column I with ideas
in the laboratory and gave experimental evidence for
origin of first form of life from pre-existing
non-living organic molecules. The primitive earth
conditions created include
listed Column II.
A.
Darwin
1.
Abiogenesis
(a) low temperature, volcanic storms, atmosphere rich in
oxygen
(b) low temperature, volcanic storms, reducing atmosphere
(c) high temperature, volcanic storms, non-reducing
atmosphere
(d) high temperature, volcanic storms, reducing atmosphere
containing CH4 , NH3 , etc.
B.
Oparin
2.
Use and disuse of organs
C.
Lamarck
3.
Continental drift theory
D.
Wagner
4,
Evolution by natural selection
191 Palaeontological evidences for evolution refer to the
(a) development of embryo (b) homologous organs
(c) fossils
(d) analogous organs
192 Fossils are generally found in
(a) sedimentary rocks
(c) metamorphic rocks
(b) igneous rocks
(d) any type of rock
193 The bones of forelimbs of whale, bat, cheetah and
man are similar in structure, because
(a)
(b)
(c)
(d)
one organism has given rise to another
they share a common ancestor
they perform the same function
they have biochemical similarities
194 Analogous organs arise due to
(a)
(b)
(c)
(d)
divergent evolution
artificial selection
genetic drift
convergent evolution
(b) Lichens
(d) Lycopodium
196 Animal husbandry and plant breeding programmes
(a)
(b)
(c)
(d)
reverse evolution
artificial selection
mutation
natural selection
B
4
1
4
3
C
2
2
3
2
D
3
3
1
1
199 Variations during mutations of meiotic
recombinations are
(a)
(b)
(c)
(d)
random and directionless
random and directional
random and small
random, small and directional
200 ( p + q ) 2 = p 2 + 2 pq + q 2 = 1, represents an
equation used in
(a)
(b)
(c)
(d)
Population genetics
Mendelian genetics
Biometrics
Molecular genetics
observed in moth, Biston betularia?
pollution indicator?
are the examples of
Codes
A
(a) 1
(b) 4
(c) 2
(d) 4
Column II
201 Which type of selection is industrial melanism
195 Which of the following is used as an atmospheric
(a) Lepidoptera
(c) Lycopersicon
Column I
(a)
(b)
(c)
(d)
Stabilising
Directional
Disruptive
Artificial
202 Evolution of life shows that life forms had a trend of
moving from
(a)
(b)
(c)
(d)
land to water
dryland to wetland
freshwater to sea water
water to land
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181
CHAPTER 07 > Evolution
(c) the young ones are protected inside the mother’s body
and are looked after they are born leading to more
chances of survival
(d) the embryo takes a long time to develop
203 Which of the following is an example for link species?
(a) Lobe fish
(c) Sea weed
(b) Dodo bird
(d) Chimpanzee
204 For the MN-blood group system, the frequencies of M
and N alleles are 0.7 and 0.3, respectively. The
expected frequency of MN blood group bearing
organisms is likely to be
(a) 42%
(b) 49%
(c) 9%
206 The most accepted line of descent in human evolution
is
NEET 2016
(a) Australopithecus → Ramapithecus → Homo sapiens
→ Homo habilis
(b) Homo erectus → Homo habilis → Homo sapiens
(c) Ramapithecus → Homo habilis → Homo sapiens
(d) Australopithecus → Ramapithecus → Homo erectus
→ Homo habilis → Homo sapiens
(d) 58%
205 Viviparity is considered to be more evolved because
(a) the young ones are left on their own
(b) the young ones are protected by a thick shell
Answers
‡
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(a)
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NEET Special Types Questions
129
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179
‡
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(a)
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NCERT Exemplar Questions
189 (c)
199 (a)
190 (d)
200 (a)
191 (c)
201 (b)
192 (a)
202 (d)
193 (b)
203 (a)
194 (d)
204 (a)
195 (b)
205 (c)
196 (b)
206 (c)
197 (c)
198 (b)
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Master The NCERT > Biology (Vol-II)
182
Answers & Explanations
4 (b) For a long time, it was believed that life came out of
5
6
7
9
10
Answers & Explanations
17
20
decaying and rotting matter like straw mud, etc.
This was the theory of spontaneous generation.
Theory of spontaneous generation (abiogenesis or
autogenesis) states that, life originated from non-living
things in a spontaneous manner.
(a) Louis Pasteur with his swan neck experiment
disapproved once and for all the abiogenesis
(spontaneous generation) and powered the concept of
biogenesis (life originated from pre-existing one).
(c) Louis Pasteur by careful experimentation
demonstrated that life comes only from pre-existing life.
They showed that in pre-sterilised flasks, life did not
come from killed yeast, while in another flask open to
air, new living organisms arose from ‘killed yeast’.
(b) Oparin and Haldane proposed that the first form of
life could have come from pre-existing non-living
organic molecules (e.g. RNA, protein, etc.) and that
formation of life was preceded by chemical evolution,
i.e. formation of diverse organic molecules from
inorganic constituents.
(a) Option (a) is correct. Experimentally, the chemical
theory of evolution was performed by SL Miller and
HC Urey in 1953.
They created electric discharge in a closed flask
containing CH4 , H2 , NH3 and water vapours at 800° C.
They observed formation of amino acids. The ratio of
methane, ammonia and hydrogen in Miller’s experiment
was 2 : 1 : 2.
(d) Miller added four gases methane, ammonia,
hydrogen and water vapours in an air tight apparatus
and passed electrical discharges from electrodes at
800°C. After a week, he found a large number of simple
organic compounds including amino acids such as
alanine, glycine, aspartic acid. In similar experiments,
other scientists observed the formation of sugar,
nitrogen bases, pigments and fats.
(d) Based on observations made during a sea voyage in
a sail ship called HMS Beagle round the world, Charles
Darwin concluded that existing living forms share
similarities to varying degrees not only among
themselves but also with life forms that existed millions
of years ago. There has been gradual evolution of life
forms. A population has been built on variations, in
characteristics. Those characteristics which enable some
to survive better in natural conditions (climate, food,
physical factors, etc.) would outbreed others that are
less-endowed to survive under such natural conditions.
(a) Alfred Wallace (1823-1913) was a British
naturalist. He wrote an essay tittle ‘On the Tendencies
of Varieties to Depart Indefinitely from the Original
Type’. Wallace was the scientist who came to the
similar conclusions around the same time of Charles
Darwin.
21 (a) Malay Archipelago is a group of islands visited by
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Alfred Wallace. It is present in South-East Asia
between Australia and the Asian mainland and it
separates the Indian and Pacific oceans. It includes
Indonesia, the Philippines and the Malaysia.
(a) Fossils are the remains of hard parts of life-forms
found in rocks. These rocks form sediments and a
cross-section of earth’s crust indicates the arrangement
of sediments one over the other during the long history
of earth.
(d) Embryological support for evolution given by Ernst
Haeckel includes the presence of row of vestigial gill
slits in embryo of all vertebrates. This proposal was
disapproved by Karl Ernst von Baer who noted that
embryos never pass these gill slits to their the adult
stages. He proposed that embryos start from few basic
forms similarly in different animals and then develop
into branching patterns.
(c) The similarity of bone structure in the forelimbs of
many vertebrates is an example of homology. The
homologous organs have the same fundamental
structure, but are adapted to perform different functions,
e.g. forelimbs of man, cheetah, whale and bat.
(a) Option (a) represents correct example of convergent
and divergent evolution. Rest of the pairs are incorrect
and the correct information is as follows
Convergent evolution involves the independent
development of similar structures in organisms that are
not directly related. It is represented by analogous
organs, e.g. eyes of Octopus and mammals, wings of
insects and birds.
In divergent evolution, same basic organs are adapted
by organisms to perform different and specialised
functions. It is represented by homologous organs, e.g.
forelimbs of vertebrates (like seal’s flipper, bat’s wing,
cat’s paw, horse’s front leg and human hand), thorns of
Bougainvillea and tendrils of Cucurbita.
(d) Eyes of Octopus, bat and man are examples of
analogous organs which show convergent evolution.
Therefore, option (d) is incorrect.
Divergent evolution results in homologous structures.
These organs have the same fundamental structure but
are different in functions. Structural homology is seen
in brain, heart and forelimbs of man, bat and cheetah.
(b) The given diagram indicates homologous organs.
Whales, bats, cheetah and human (all mammals) share
similarities in the pattern of bones of forelimbs. In
plants, the thorns and tendrils of Bougainvillea and
Cucurbita, respectively represent homology.
(c) The analogous organs are not anatomically similar
structures but these perform similar functions. Hence,
analogous structures are a result of convergent
evolution, i.e. different structures evolving for the same
functions and hence, show similarity.
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61 (d) In Australia, marsupials and placental mammals
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have evolved to share many similar characteristics. This
type of evolution is referred to as convergent evolution.
Convergent evolution is the independent evolution of
similar features in species of different lineages. For
example, a number of marsupials, each different from
the other evolved from an ancestral stock, but all within
the Australian Island continent. Also, marsupials in
Australia resemble placental mammals in the rest of the
world, they evolved in isolation after Australia separated
from other continents.
(c) Option (c) is correct.
Adaptive radiation occurs when a population of a
species invades a new area. It is because it provides the
organisms of the population a new habitat with plenty
of niche spaces. Darwin’s finches represent one of the
best examples of this phenomenon.
(a) Darwin’s fitness is related to and organism’s ability
to survive and reproduce better than the other members
of the species under abnormal environmental conditions.
(b) The organisms, which acquire or develop favourable
variations would survive because they are fittest to face
their surrounding, while unfit organisms are eliminated.
(b) Darwinian fitness can be estimated by the number
of offspring produced by different individuals in a
population. The organisms which bear favourable
variations in accordance to the environment have more
offspring than the others which do not have variations in
accordance with environment.
(c) Sexual selection is an example of natural selection
as it is the type of natural selection in which one sex is
preferred for certain characteristics by the individuals of
other sex.
Natural selection involves the selection of those animals
which are better adapted to an environment for
reproduction and growth (survival).
(d) Reproduction by sexual methods brings about
changes in genes of progeny. In genes of sexually
reproduced organisms, independent assortment of genes
and genetic recombination takes place. Due to these
events, the progeny have high rate of natural selection
than the asexually repoducing organisms.
(b) Darwin stated that the organic evolution is due to
the interspecific competition. It is the competition
between members of different species. Intraspecific
competition occurs amongst members of the same
species for obtaining optimum amounts of their food,
shelter, mate, water, light, etc.
(b) Natural selection theory of Darwin did not believe
in any role of discontinuous variation. Darwin called
these variations as sports, while Hugo de Vries used the
term mutation for these variations. These variations are
sudden heritable changes, which can occur in any stage
of development.
(a) Hugo de Vries proposed that the variations caused
by mutation are random and directionless. These are the
sudden, heritable changes in the genetic material and
these variations constitute the raw material for
Answers & Explanations
39
The eyes of Octopus and eyes of cat are examples of
analogous organs. That have evolved due to the
convergent evolution.
(b) Convergent evolution refers to independent
evolution of similar features in species of different
periods in time. These features evolve in response to
common environmental abnormalities.
Thus, option (b) is correct.
(c) Biochemical similarities are based on the study of
similarities in protein and genes of organisms. These
biochemical similarities point towards same shared
ancestry as structural similarities among diverse
organisms.
(a) Change of lighter coloured variety of peppered
moths (Biston betularia) to darker variety in the
industrial area
occurred due to the selection of darker variety for
survival. It is an excellent example which supports the
theory of natural selection by Charles Darwin.
(d) Industrial melanism is an adaptation where the
moths living in the industrial areas developed melanin
pigments to match their body to the black soot (smoke)
covered surroundings. Before industrialisation, all
moths were white and were unnoticed from predatory
birds. After industrialisation, white moths were more
evidently visible and thus, picked up by birds. But
black moths escaped unnoticed, so they managed to
survive resulting in more population of black moths and
less population of white moths.
(c) Lichens are very sensitive to air pollution specially
to gas sulphur dioxide. Lichens are the symbiotic
association of algae and fungi. Generally, lichens are
not found in polluted industrial areas.
(b) Industrial melanism is the term used to describe the
evolutionary process in which darker moths came to be
predominate over the lighter moths, since the industrial
revolution in England in 1850s as a result of natural
selection.
(c) Evolution is not a direct process and is based on
chance events and chance mutations in organisms.
Thus, it is a discontinuous and stochastic process.
(b) Development of different functional structures from
a common ancestral form is called adaptive radiation.
The concept of adaptive radiation in evolution was
developed by HF Osborn in 1902. Homologous organs
show adaptive radiation.
(a) The diversity in the type of finches and adaptation
to different feeding habits on the Galapagos islands was
observed by Darwin. He provides an evidence of origin
of species by natural selection.
(c) Darwin explained that adaptive radiation gave rise
to the varieties of marsupials (pouched mammals) in
Australia by the same process of adaptive radiation as
found in the finches of Galapagos Islands.
(d) Lemur and spotted cuscus are not examples of
adaptive radiation. These are examples of convergent
evolution.
Rest of the pairs are examples of adaptive radiation.
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evolution. He also proposed that mutations play a key
role in speciation and used the term saltation for single
step large mutations.
81 (a) Hardy-Weinberg principle is applicable for allelic
frequency of non-evolving population under stable
conditions.
82 (b) Hardy-Weinberg principle states that allele
frequencies remains constant from generation to
generation. This is called as genetic equilibrium.
85 (b) The frequency of homozygous dominant,
heterozygous and homozygous recessive individuals
would be 0.16 (AA); 0.48 (Aa); 0.36 (aa). The
frequencies are calculated as follows
Frequency of dominant allele (p) = 0.4 (given)
Frequency of recessive allele (q) = 1 − 0.4 = 0.6
Frequency of homozygous dominant individuals (AA) =
p 2 = (0.4)2 = 0.16
Frequency of heterozygous individual (Aa)= 2 pq
= 2 ( 0.4 ) ( 0.6 ) = 0.48
Frequency of homozygous recessive individual (aa)
= q 2 = ( 0.6 )2 = 0.36
87 (b) Hardy-Weinberg principle states that the allele
frequencies in a population are stable and remain
constant from generation to generation. This can be
expressed by the equation
p 2 + 2 pq + q 2 = 1 or ( p + q )2 = 1
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Answers & Explanations
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where, p 2 represents frequency of homozygous
dominant genotype, 2 pq represents the frequency of
heterozygous genotype and q 2 represents the frequency
of homozygous recessive genotype.
Hence, option (b) is correct.
(d) The tendency of population to remain in genetic
equilibrium may be disturbed by lack of random mating.
When in a population allele or gene frequencies remain
same over generations, the population is said to be
non-evolving and in genetic equilibrium. This
equilibrium is disturbed by following factors, i.e.
mutation, gene flow, geneic drift, natural selection and
no random mating.
(a) Sometimes the change in allele frequency is so
different in the new sample of population that they
become a different species. The original drifted
population becomes the founder of new population and
the effect is called founder effect.
(a) Genetic drift is a drastic change in allele frequency
when population size is very small. Its effects are more
marked in a small isolated population.
(c) Option (c) represents the correct labellings and the
description is as follows
l
Stabilising selection (Balancing selection) This type of
selection favours average sized individuals, while
eliminates small sized individuals. It reduces variation
and hence, does not promote evolutionary changes.
Hence, it is given by Type I graph
l
l
Directional selection (Progressive selection) In this
selection, the population changes towards one particular
direction. It means this type of selection favours small
or large-sized individuals and more individuals of that
type will be present in new generation. The mean size of
the population changes. Hence, it is given by Type II
graph.
Disruptive selection (Diversifying selection) This type
of selection favours both small-sized and large-sized
individuals. It eliminates most of the members with
mean expression, so as to produce two peaks in the
distribution of the trait that may lead to the development
of two different populations. This kind of selection is
opposite of stabilising selection and is rare nature but is
very important in bringing about evolutionary changes.
Hence, it is given by Type III graph.
94 (b) Directional selection leads to change in the
phenotypic characters of a population in one direction. In
the case of artificial selection to obtain high milk yielding
cows, it is intentionally done to increase the milk
production, hence, it is directional. This is because only
high milk yielding cows are produced.
95 (c) Option (c) is correct. Albinism is an autosomal
recessive genetic disorder. It is given that frequency of
an albino in a population is 1 in 10,000, i.e. 0.0001.
According to Hardy-Weinberg law p 2 + q 2 + 2 pq = 1
Now, q 2 = 0.0001
q = 0.0001 = 0.01
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Also, p + q = 1 So, p = 0.99
Hence, 2 pq = 2 × 0.01 × 0.99 = 0.02 or 2%
Accordingly, 2 individuals in 10000 will be carriers of
albinism.
(a) Allopatric speciation occurs when genetically
related populations inhabit widely separated
geographical area. The population becomes entirely
separated and finally constitutes a new species.
Formation of Darwin’s finches that formed separate
species in Galapagos islands is an example of allopatric
speciation.
(c) The pair in option (c) is incorrect and can be
corrected as follows.
First organisms that invaded land were supposed to be
plants and not single-celled animals.
Rest of the pairs are correct.
(d) Azoic means no life. It was the era which prevailed
during the origin of earth. At that time, there was no
hostile conditions for the survival of any living
organisms.
(c) Cenozoic era is also called the age of mammals. In
this era, the first mammals originated on earth.
(c) Archaeopteryx (Archlae –primitive; pteryx – wing )
is an extinct animal. It was found in the rocks of
Jurassic period. It was discovered by Andreas Wagnar
in 1861. It displayed the characters of both reptiles and
birds.
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CHAPTER 07 > Evolution
129 (a) Both Assertion and Reason are true and Reason is
Its corrected form is as follows
Tyrannosaurus rex was the biggest land reptile which
was about 20 feet in height and had huge dagger-like
teeth. Fish like reptile was Ichthyosaurus.
Rest of the pairs are correctly matched.
113 (b) In the quaternary period there were two epochs
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Holocene including only modern humans.
Pleiostocene including ice age and various human
species.
130
115 (d) Option (d) represents the incorrectly matched pair.
It can be corrected as
Two mya Australopithecus probably lived in East
African grasslands. Evidences show that they hunted
with stone weapons but essentially ate fruits.
Rest of the pairs are correct.
119 (b) Neanderthal man with a brain size of 1400 cc lived
in near East and Central Asia, Europe and North Africa
between 10,00,00 to 40,000 years back. It had slightly
prognathus face, sloping forehead, eyebrow ridges,
smaller or no chin, large receding jaws, thick-boned
skull and high domed head.
120 (a) Homo erectus (Erect man) appeared about
1.7 million years ago in middle Pleiostocene.
Homo erectus was evolved from Homo habilis. He was
about 1.5-1.8 metres tall. He was the progenitor of two
main sub species Neanderthal and Cro-Magnon man.
122 (b) Cro-Magnon man or Homo sapiens fossilis was
more intelligent than modern man. They were cave
dwellers having prominent chin and appeared after
Neanderthal man. The cranial capacity of Cro-Magnon
man was 1650 cm 3 and that of living modern man is
1450 cm 3 .
123 (c) The most significant trend in the evolution of
modern man is the increased brain capacity from the
ancestors. The first human being was the hominid,
called Homo habilis. Their brain capacity was between
650-800 cc.
126 (a) Homo sapiens arose in Africa and moved across
continents and developed into distinct races. During the
ice age between 75,000-10,000 years ago modern Homo
sapiens arose. Pre-historic cave art developed about
18,000 years ago. One such cave paintings by
Pre-historic humans can be seen at Bhimbetka rock
shelter in Raisen district of Madhya Pradesh.
Agriculture came around 10,000 years back and human
settlements started.
127 (a) The chronological order of human evolution is as
follows
Ramapithecus (earliest hominid fossil about 14-15 mya)
↓
Australopithecus (first ape man about 2 mya)
↓
Homo habilis (tool maker handyman about 1.2-1.5 mya)
↓
Homo erectus (Erect man about 1.5 mya)
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the correct explanation of Assertion.
Theory of chemical evolution states that life originated
from pre-existing non-living organic molecules and the
formation of life was preceded by chemical evolution.
The conditions on primitive earth which favoured
chemical evolution were high temperature (4800°C),
volcanic storms and a reducing atmosphere that
contained CH4 , NH3 , water vapours, etc.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
The theory of special creation states that God created
life by his divine act of creation. This theory lacked
scientific evidences and thus was not accepted.
Theory of spontaneous generation states that life
originated from decaying and rotting matter like straw,
mud, etc. Louis Pasteur rejected the theory of
spontaneous generation and demonstrated that life came
from pre-existing life froms.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Earth is about 4.5 billion years old. Primitive earth had
no atmosphere and contained water vapours,
CH4 , CO2 , NH3 . Life appeared 500 million years back
after the formation of earth.
(b) Both Assertion and Reason are correct, but Reason
is not the correct explanation of Assertion.
Primitive earth was devoid of oxygen and hence, only
those organisms which were able to survive in
anaerobic condition developed. All those organisms
were heterotrophic. Later, after autotrophic organisms
developed, which used inorganic sources such as H2 S,
NH3 , CH4 as source of energy. These organisms were
called chemoautotrophs.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Coacervates were aggregates of organic biomolecules
surrounded by film of water molecules. These lacked
definite membrane, but did exhibit some life like
characters. Microspheres were non-living collections of
organic macromolecules, double-layered and formed
from proteinoids, by heating a mixture of amino acids at
180°C.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Ernst Haeckel supported the embryological similarities
as an evidence of evolution. He gave the biogenetic law,
‘Ontogeny recapitulates phylogeny’ which states that an
organism repeats its ancestral history during its
development. The embryos of all vertebrates including
humans develop a row of vestigial gill slits which
degenerate and are absent in adult vertebrates.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Darwin believed that the small and useful variations
make some species more adapted to the changing
environment than others.
Answers & Explanations
111 (b) Option (b) represents the incorrectly matched pair.
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Answers & Explanations
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146
Out of heterogeneous population, nature selects the best
adaptative individuals, while less fit or unfit individuals
are rejected because they fail to survive and reproduce.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Whales and mammals share similarities the pattern of
bones of forelimbs because these organs are
homologous organs and suggest occurrence of divergent
evolution. Homologous organs follow the basic plan of
organisation during development, but in adult stage,
they modified to perform different functions as an
adaptation to different environments.
(c) Assertion is true, but Reason is false and it can be
corrected as
Divergent evolution gives rise to homology. Analogy
arises due to convergent evolution.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Lichens are good pollution indicators. These do not
grow in areas that are polluted because these organisms
are sensitive to SO 2 gas present in polluted areas up to
great concentration.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Lichens are the symbiotic relationship of algae and
fungi. These are good pollution indicators because these
are sensitive to SO2 levels in air.
(c) Assertion is true, but Reason is false and can be
corrected as
Mutations are sudden changes which bring sudden
variations in organism.
(c) Assertion is true, but Reason is false and can be
corrected as
If the gene migration happens multiple times, it is called
gene flow. Gene recombination occurs due to the
independent assortment of chromsomes, crossing over
during meiosis, random fusion of gametes and the
formation of new alleles.
(c) Assertion is true, but Reason is false and can be
corrected as
Mutations lead to speciation and hence, Lamarck called
it saltation and proposed Lamarckism. Lamarckism was
rejected by August Weismann who proposed the theory
of continuity of germplasm.
Sudden inheritable changes take place in genome of an
organism due to certain factors called mutations.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Among the primates, chimpanzee is the closest relative
of the present day humans. This is because the banding
pattern in the autosome number 3 and 6 of man and
chimpanzee is remarkably similar.
(c) The statement in option (c) is true regarding the
theory of natural selection. Other statements are
incorrect and can be corrected as
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Lamarckism is the first theory of organic evolution.
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Palaeontology explains the information derived from
fossils.
Modern synthetic theory of evolution explained the
concept of speciation.
147 (b) The statement in option (b) is incorrect for
Darwinism. It can be corrected as
Mutations are random and directionless, while
Darwinian variations are small and directional.
Evolution according to Darwin was a gradual process.
Rest of the statements are correct.
152 (d) Statement IV stands in favour of abiogenesis which
states that life originated from non-living matter.
Other statements are incorrect for biogenesis as these
statements support the theory of biogenesis.
153 (b) Statements I and V are correct representation of
homologous organs. Hands of man and wings of bat, as
well as forearm of humans and forelimbs of horses are
the examples of homology because these have same or
common origin (i.e. similarity in pattern of bones), but
have different functions.
Rest of the statements are incorrect and can be
corrected as
Wings of cockroach and wings of bats as well as wings
of birds and wings of butterfly are analogous organs.
154 (d) Statements II, III and IV are correct whereas I is
incorrect. Its correct form is as follows
Wings of insects and birds are analogous organs
because they perform the same function, but have
different origins.
155 (d) Statements II and III are incorrect and their
corrected forms are as follows
l
l
Natural selection includes variation.
Theory of natural selection was given by Charles
Darwin. This theory states that the variations which are
favourable to environment and inheritable are the major
cause of evolution.
Rest of the statements, i.e. statement I, IV and V are
correct.
156 (d) Statements I, II, III, IV and VI are correct, while
statement V is incorrect. Its corrected form is as follows
Genetic drift is the random change in the frequency of
alleles in a population over successive generation due to
the sampling error in gametes. It operates in small
populations.
157 (d) Statements I, II and III are true for genetic drift.
Statement IV is incorrect and can be corrected as
Migration rather than mutation is primary responsible
for genetic drift as it operates in small populations.
159 (d) Statements I, II and IV. But statement III is
incorrect and can be corrected as
Theory of acquired character was given by Lamarck
(also called Lamarckism). Mutational theory of
evolution was given by Hugo de Vries which states that
sudden inheritable change is the cause of evolution.
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CHAPTER 07 > Evolution
corrected as
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l
Evolution is always considered as the appearance of
characters should also be transmitted to the offspring
otherwise the changes are lost.
Adaptive ability cannot be considered as evolution
because this ability may be temporary due to the
environmental changes.
Rest of the statements are correct.
161 (a) Statement I and II are correct conditions to determine
that two species are different. This can be explained as
Species are a group of interbreeding individuals
producing fertile offsprings. If two individuals fails to
follow this criteria they belongs to different species.
But members of a species can have different body colour
and appear morphologically slightly different. Therefore,
these criterias do not justify that two individuals are of
different species.
162 (c) Statements III and IV are correct for organic
evolution, while statements I and II are incorrect. It can be
corrected as
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177 (b) Statement IV is incorrect about Homo habilis. It
can be corrected as
Homo habilis had about 700 cc cranial capacity. Ape
man had about 500 cc cranial capacity.
Rest of the statements are correct.
178 (a) Statements III and IV are incorrect and can be
corrected as
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189 (c) The theory of spontaneous generation stated that
190
Homologous structures have the same embryonic origin
and basic structure, but they do not perform same
function, e.g. flipper of whale and wings of bat.
Analogous organs are the structures which are different in
their basic structure and developmental origin, e.g. wings
of butterfly and wings of bird.
167 (c) Statements I and IV are correct.
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Mendel’s laws of inheritance and Weismann’s theory of
continuity of germplasm (1892) discarded Lamarck’s
concept of inheritance of acquired characters. These two
concepts gave the insight of inheritance pattern in
organisms and the mechanism inovled in it.
(d) According to modern theory of evolution, the five
factors involved in the process of organic evolution are as
mutations, genetic drift, gene migration (gene flow), gene
recombination and hybridisation.
Thus, statements I, II and III support the modern theory of
evolution.
(d) Statements I, II, IV and V are correct and statement
III is incorrect. It can be corrected as
Genetic drift is the random change in the allele frequency
caused by sampling error across generation in a definite
population. The consequences of genetic drift are not
predicted that is why it is called non-directional.
(c) Statements II and III are correct for natural selection.
Statement I is incorrect and it can be corrected as
Natural selection tends to increase the characters that
inturn increases the chances of survival and reproduction
of an organism.
(a) Statements II and IV are correct. Statements I and III
are incorrect and can be corrected as
l
l
Gene mutations are random changes in the bases of
sequences of genes.
Genetic drift is also called Sewall Wright effect.
Neanderthal man had a slightly prognathous face
(having a forward projecting face and jaws).
Cro-Magnon man is regarded as most recent ancestor
of today’s man.
Rest of the statements are correct.
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193
194
life can arise from non-living things only. It is also
known as the theory of abiogenesis.
Louis Pasteur by careful experimentation disapproved
this theory and demonstrated that life arose from
living forms (pre-existing life).
(d) The primitive earth conditions include high
temperature, volcanic storms and reducing
environment containing methane ( CH4 ), ammonia
( NH3 ), hydrogen ( H2 ) and water ( H2 O ).
The Miller-Urey experiment tested for the occurrence
of chemical evolution by stimulating hypothetical
conditions present on early earth.
They ultimately found that a large number of simple
organic compounds including some amino acids such
as alanine, glycine and aspartic acid can be
synthesised as during chemical origin of life.
(c) Palaeontological evidences for evolution refer to
the evidences obtained from fossils. Fossils are the
preserved remains or traces of organisms from the
distant past. The study of fossils is called
Palaeontology.
Homologous and analogous organs provide evidences
for comparative anatomy and morphology.
(a) Fossils are generally found in sedimentary rocks,
which are formed by the gradual deposition of silt,
sand or calcium carbonate over millions of years in
regions such as lakes or sea.
During their formation, the dead animals are carried
to the sea or large lake, sink down and get burried in
the rocks. The animals, thus preserved in the rocks,
are converted into fossils.
(b) The bones of forelimbs of whale, bat, cheetah and
man are similar in structure, because they have a
common ancestor.
These are homologous organs which have different
functions across diverse forms, but are developed
along the same pattern. These organs arise due to
divergent evolution.
(d) Analogous organs arise due to the convergent
evolution. These organs have similar functions, but
are different in their structural details and origin, e.g.
wings of insect and bird.
Answers & Explanations
160 (b) Statements II and III are incorrect and can be
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Master The NCERT > Biology (Vol-II)
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201 (b) Directional selection is observed in the moth, Biston
indicator. These do not grow in areas that are polluted,
as they are sensitive (especially phycobiont) to oxides
of nitrogen and sulphur hence, unable to synthesise
organic food and do not grow well.
197 (c) Appearance of antibiotic-resistant bacteria is an
example of pre-existing variation in the population.
When a bacterial population encounters a particular
antibiotic, those sensitive to it die. But some bacteria
having mutations become resistant to the antibiotic.
Soon, the resistance providing genes become
widespread and the entire population becomes
resistant to that particular antibiotic.
199 (a) Variations during mutations of meiotic
recombinations are random and directionless. Hugo de
Vries based on his work on evening primrose stated
that it is mutation, which causes sudden appearance of
variations that results in speciation.
He stated that mutations are sudden, heritable and
persistant in successive generation. He contradicted
Darwinian variations which are stated as small and
directional.
200 (a) (p + q) 2 = p 2 + 2 pq + q 2 = 1represents an
equation used in population genetics.
It is the mathematical representation of
‘Hardy-Weinberg principle’. This principle says that
allele frequencies in a population are stable and is
constant from generation to generation, i.e. the gene
pool remains a constant.
betularia during industrial melanism. Under this,
individuals at one end of the frequency distribution are
favoured and so more individuals of that type will be
present in the next generation.
202 (d) Evolution of life shows that life forms had a trend of
moving from water to land. The early vertebrates were
fishes (which lived in only water). Some fishes gradually
changed into amphibians (can live both on land and in
water). Certain amphibians then transformed into the
reptiles (live on land) some of the later finally evolved
into birds (can fly) and than mammals. Thus, showing
that life forms moved from water to land.
204 (a) The expected frequency of MN-blood group bearing
organisms is likely to be 42%. If the frequencies of M
and N alleles are 0.7 and 0.3, respectively, the frequency
of MN-blood group can be calculated as follows
Frequency of MN-blood group = 2 pq
= 2 × 0.7 × 0.3
= 0. 42 or 42%
205 (c) Viviparity is considered to be more evolved because
the youngs ones are protected inside the mother’s body
and are looked after once they are born, leading to more
chances of survival, e.g. mammals.
However, in oviparity, the female lays fertilised /
unfertilised eggs covered by a hard calcareous shell in a
safe place in the environment. The chances of survival
are less as the young ones are left on their own.
Answers & Explanations
195 (b) Lichens can be used as an atmospheric pollution
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CHAPTER > 08
Human Health
and Diseases
NEET
Å
Health is a state of complete physical, mental and social
well-being rather than only physical fitness or the absence of
disease.
n
n
Å
Å
KEY NOTES
Health is affected by genetic disorders, infections and life
style.
Balanced diet, personal hygiene, regular exercise, rest and
thinking are very important to maintain good physical
and mental health.
Awareness about diseases and their effect on different body
functions, vaccination against infectious diseases, proper
disposal of wastes, control of vectors, maintenance of hygienic
food and water resources all are necessary for health.
Disease is the condition of improper functioning or any
condition which interferes with the normal functioning of
one or more organs of the body and causes disorder of mind
or body. It is characterised by various signs and symptoms.
Diseases can be broadly classified into
n
n
Congenital diseases These diseases are present in human
since birth (genetic disorders) or are caused due to
mutation, e.g. Down‘s syndrome, sickle-cell anaemia, etc.
Acquired diseases These diseases develop after birth and
are not transferred from parents to offspring. These
diseases are further categorised into
n
n
Infectious diseases or Communicable diseases These
diseases are easily transmitted from a diseased person
to a healthy person. The infectious diseases are very
common, e.g. AIDS, common cold, etc.
Non-infectious diseases or Non-communicable
diseases These diseases cannot be transmitted from a
diseased person to a healthy person. These diseases are
caused by agents other than pathogens, e.g. cancer,
diabetes, etc.
Common Diseases in Humans
Å
Pathogen is an organism which can cause disease in human.
These can belong to bacteria, viruses, fungi, protozoans,
helminths, etc.
Å
Most parasites are therefore pathogens as these cause harm
to the host by inhabiting them.
Å
The pathogens can enter our body by various means,
multiply and interfere with normal vital activities and cause
morphological and functional damage.
Å
Pathogens have to adapt to life within the environment of
the host, e.g. the pathogens that enter the gut must know a
way of surviving in the stomach at low pH and resisting the
various digestive enzymes.
Å
Vectors, on the other hand, do not cause disease themselves,
but act as carriers to transmit the pathogen from an infected
person to a healthy person, i.e. spread the disease, e.g.
famale Anopheles mosquito.
Å
Some common diseases and their pathogenic members are
discussed as follows
Bacterial Diseases
Some common bacterial diseases are as follows
1. Typhoid is caused by a bacterium called Salmonella typhi.
Å
S. typhi enters the small intestine through contaminated
food and water and migrate to other organs through
food and blood.
Å
Symptoms are high fever (39-40°C), weakness, stomach
pain, constipation, headache and loss of appetite.
Intestinal perforation and in severe cases death may
occur.
Å
Widal test is the confirmatiory test for diagnosis of
typhoid.
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190
2. Pneumonia is caused by Streptococcus
pneumoniae and Haemophilus influenzae.
Å
These bacteria infect alveoli of the lungs.
The alveoli get filled with a fluid which
causes decrease of respiratory efficiency of
the lungs.
Å
Pneumonia spreads by inhaling
droplets/aerosol from infected individuals,
sharing glasses and utensils with an
infected person.
Å
Symptoms of pneumonia are fever, chills,
cough, headache, etc. In severe cases, the
lips and finger nails may turn grey bluish in
colour.
3. Plague is caused by Pasteurella/Yersinia pestis
and is also called black death.
4. Diphtheria is caused by Corynebacterium
diphtheriae and is characterised by difficulty in
breathing due to infection in the mucous
membrane of upper respiratory tract.
Å
When the mosquito
bites another human,
sporozoites are
injected with bite.
Mature infective stages
(sporozoites) escape
from gut and migrate
to the mosquito
salivary glands.
Sporozoites
Salivary glands
Mosquito Host
Fertilisation
and
development
take place in
the mosquito’s
gut.
s
yte
Female
toc
e
m
mosquito
Ga
takes up
Female
gametocytes
with blood
Male
meal.
Common cold occurs due to a group of viruses
called rhino viruses.
Å
These viruses infect the nose and the
respiratory passage, but not the lungs.
Å
Symptoms include nasal congestion and
discharge, sore throat, hoarseness, cough,
headache, tiredness, etc., which generally last
for 3-7 days.
Å
The infection occurs when droplets from cough
or sneeze of an infected person are either
inhaled directly or transmitted through
contaminated objects such as pen, books, cups,
computer’s keyboard or mouse, etc.
Parasites
(sporozoites)
reach the liver
through blood.
Human
Host
Sexual stages (gametocytes)
develop in red blood cells.
Viral Diseases
Å
Life cycle of Plasmodium is given in the figure below
Å
Thus, malarial parasite requires two hosts to complete its life
cycle, i.e. human and mosquito.
2. Amoebiasis (amoebic dysentery) is caused by an intestinal
endoparasite, Entamoeba histolytica, which is a protozoan parasite of
the large intestine of humans.
Å
Carrier of pathogens is housefly. It transmits the parasite from
faeces of an infected person to the food.
Å
Infection takes place through the contaminated food and water.
Å
Symptoms are abdominal pain, constipation, cramps, faeces with
excess mucus and blood clots.
Helminthic Diseases
Some common protozoan diseases are as
follows
Some common helminthic diseases are as follows
NEET
Parasites reproduce
asexually in red blood
cells, then bursting them
and release haemozoin
toxin which causes
cycles of fever and other
symptoms. Released
parasites infect
new red blood cells.
Stages in the life cycle of Plasmodium
Protozoan Diseases
1. Malaria is caused by different species of the
protozoan Plasmodium (vivax, malariae and
falciparum).
Å P. falciparum causes most serious kind of
malaria which can be fatal.
Å Female Anopheles mosquito is the vector of
Plasmodium which transfers the sporozoites
(infectious form).
The parasite
reproduces asexually
in liver cells, bursting
the cell and releasing
into the blood.
1. Ascariasis is caused by an intestinal endoparasite of human, Ascaris
lumbricoides commonly called as roundworm.
Å Infection occurs as the eggs of parasite excreted along with faeces
of infected person, contaminate water and soil.
Å
Å
Infection reaches human beings through contaminated
vegetables, fruits and water.
Symptoms of disease are abdominal pain, indigestion, muscular
pain, fever, anaemia, nausea, headache and the blockage of
intestinal passage.
KEY NOTES
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CHAPTER 08 > Human Health and Diseases
2. Filariasis/Elephantiasis is caused by filarial worms
Wuchereria bancrofti and Wuchereria malayi.
Å
Culex mosquito (female) is the vector.
Å
Symptoms are chronic inflammation of organs in
which they live, blockage of lymph vessels of lower
limbs resulting in swelling.
Å
Genital organs also get affected leading to their
deformation.
1. Innate Immunity
It is present from birth and is inherited from the parents. It
is non-specific and consists of following four types of
barriers
Å
Physical barriers prevent entry of microorganisms in the
body. For example, skin, mucus coating of epithelium
lining of respiratory, gastrointestinal and urogenital tracts.
Å
Physiological barriers prevent microbial growth in the
body. For example, acid in the stomach, saliva in the
mouth, tears from eyes.
Å
Cellular barriers phagocytose and destroy microbes. For
example, some WBCs like Polymorpho-Nuclear
Leucocytes (PMNL- neutrophils) and monocytes and
natural killer cells (type of lymphocytes) in the blood as
well as macrophages in tissues.
Å
Cytokine barriers Virus-infected cells secrete proteins
called interferons, which protect non-infected cells from
further viral infection.
Fungal Diseases
Ringworm is caused by fungi of the genera–Microsporum,
Trichophyton and Epidermophyton.
Å
Infection occurs through contact with an infected person or
from soil, through the use of towels, clothes, combs, etc., of
an infected person.
Å
Symptoms of ringworm are appearance of dry, scaly
lesions on various parts of the body such as skin, nails and
scalp accompanied by intense itching.
Å
Heat and moisture help these fungi to grow in regions like
folds as in groin or between the toes.
2. Acquired Immunity
Å
The immunity acquired after birth is called acquired
immunity.
Å
Acquired immunity is pathogen specific.
Å
It is characterised by memory. This means when our body
encounters a pathogen for the first time it produces a
response called primary response which is of low intensity.
Å
Subsequent encounter with the same pathogen elicits a
highly intensified secondary or anamnestic response. This
is ascribed to the fact that our body appears to have
memory of the first encounter.
Å
The primary and secondary immune responses are carried
out with the help of two special types of lymphocytes
present in our blood, i.e. B-lymphocytes and
T-lymphocytes.
Å
The B-lymphocytes produce an army of proteins in
response to pathogens into our blood to fight with them.
These proteins are called antibodies.
Å
The T-cells themselves do not secrete antibodies but help
the B-cells to produce them.
Immunity
Å
The acquired immunity may be active or passive.
It is the ability of the body (host) to fight against disease
causing agents. Immunity is of two types.
Å
Active immunity is generated by the body on exposure to
antigen. Active immunity can also be achieved through
vaccination, e.g. polio vaccine, tetanus vaccine, etc.,
(artificially acquired). On the basis of action of
responding cell, active immunity is of two types
Prevention and Control of
Infectious Diseases
Å
Å
Maintenance of personal and public hygiene is very
important for prevention and control of many infectious
diseases. Personal hygiene includes keeping the body
clean, consumption of clean drinking water, food, etc.
Public hygiene includes proper disposal of waste and
excreta, periodic cleaning of water reservoirs, etc.
Other preventive measures include
n
n
n
n
n
Eradication of vectors and destroying their breeding
sites.
Use of mosquito nets and repellants.
Introducing fishes like Gambusia in pond that feed on
mosquito larva.
Vaccination and immunisation programmes for diseases.
Use of antibiotics and other drugs can significantly and
effectively treat infectious diseases.
Immunity
Innate immunity
(inborn immunity)
Acquired immunity
(adaptive immunity)
Active immunity
Passive immunity
n
Cell-mediated immunity This immunity is due to
T-lymphocytes, which mature in thymus. The graft
rejection during organ transplantation is due to the
ability of the T-cells to differentiate between self and
non-self is cell-mediated immunity.
NEET
KEY NOTES
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Master The NCERT > Biology (Vol-II )
192
n
Å
Humoral immunity This is due to B-lymphocytes,
which secrete specific antibody when exposed to a
particular antigen. These antibodies flow into the body
fluids and neutralise the antigen.
Passive immunity develops due to direct transfer of
actively formed antibodies. For example, the yellowish
fluid colostrum secreted by mother during the initial
days of lactation has abundant antibodies (IgA) to protect
the infant. The foetus also receives some antibodies from
their mother, through the placenta during pregnancy.
Å
Allergy
Å
It is the exaggerated response of the immune system to
certain antigens present in the environment known as
allergens.
Å
These can be pollen grains, animal dander, dust, feathers,
penicillin drugs, etc.
Antibodies
Å
Å
Å
n
These are the proteins (immunoglobulin) produced within
the body by the plasma cells against antigens.
n
The basic structure of all antibody/ Immunoglobulin (Ig)
molecule consists of four polypeptide chains linked by
disulphide bonds. Two small chains called light chain and
two longer chains called heavy chain are present.
Five different types of immunoglobulins are known and
these are as follows
Antibody
Description
IgG
Most prevalent class of antibody, 75-80% of total
antibody.
It can cross placenta from mother to child and confer
immune protection to newborns.
IgM
They are the first to be produced in response to encounter
with a pathogen.
Responsible for blood transfusion reactions in ABO blood
system.
IgA
Found in colostrum, i.e. breast milk for newborns to
provide passive immune protection.
IgE
It is involved in allergic reactions.
IgD
It resembles IgG structurally and serves as a recognition
receptor for antigen. It activates and suppresses
lymphocyte activity.
Vaccination and Immunisation
Å
The process of introduction of inactivated or weakned
pathogen into the body to provide protection against a
disease is called vaccination.
Å
Immunisation is the process by which the body produces
antibodies against the vaccine (primary response) and
develops the ability to neutralise pathogens during actual
infection in the body (secondary response).
Å
Vaccine generates B and T-cells that recognise the
pathogens on subsequent exposure and produce an
intense immune response.
Å
In case of requirement of quick immune response like
tetanus or snake bite infection, pre-formed antibodies or
antitoxin (a preparation containing antibodies to the toxin)
are injected into the patient. This is called passive
immunisation.
NEET
Recombinant DNA technology has produced antigenic
polypeptides of pathogen in bacteria or yeast. This
allowed large scale production of vaccines, e.g. hepatitis-B
vaccine from yeast.
n
n
IgE antibodies are produced in response to allergens.
Causes of allergy are histamine and serotonin released
from the mast cells.
Symptoms of allergy are sneezing, watery eyes,
running nose, difficulty in breathing.
Treatment of allergy include doses of antihistamine,
adrenaline and steroids.
Autoimmunity
Å
Higher vertebrates’ immune system can distinguish
foreign molecules as well as foreign organisms and mount
a response to destroy them.
Å
But sometimes, due to genetic and other unknown
reasons, the body attacks self cells. This results in damage
to the body this is called autoimmunity and the disease is
called auto-immune disease.
Å
Rheumatoid arthritis which affects many people in our
society, myasthenia gravis, etc. are some examples of
auto-immune diseases.
Immune System in the Body
Å
The human immune system consists of lymphoid organs,
tissues, cells and soluble molecules like antibodies.
Å
The immune system also plays an important role in
allergic reactions, auto-immune diseases and organ
transplantation.
Lymphoid Organs
Å
These are the organs where origin and/or maturation and
proliferation of lymphocytes occur. The primary
lymphoid organs are bone marrow and thymus where
immature lymphocytes differentiate into antigen-sensitive
lymphocytes.
Å
After maturation, the lymphocytes migrate to secondary
lymphoid organs like spleen, lymph nodes, tonsils,
Peyer’s patches of small intestine and appendix. The
secondary lymphoid organs provide the sites for
interaction of lymphocytes with the antigen, which then
proliferate to become effector cells.
KEY NOTES
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CHAPTER 08 > Human Health and Diseases
Å
The bone marrow is the main lymphoid organ where all
blood cells including lymphocytes are produced.
Å
Both bone marrow and thymus provide micro-environments
for the development and maturation of T-lymphocytes.
Å
The spleen is a large bean-shaped organ. It mainly contains
lymphocytes and phagocytes. It acts as a filter of blood by
trapping blood-borne microorganisms. It is also called the
graveyard of RBCs.
Å
The lymph nodes are small solid structures located at
different points along the lymphatic system. Lymph nodes
serve to trap microorganisms or other antigens, which
happen to get into the lymph and tissue fluid.
Å
A lymphoid tissue is also located within the lining of the
major tracts (respiratory, digestive and urogenital tracts)
called Mucosal Associated Lymphoid Tissue (MALT). It
consititutes about 50 per cent of the lymphoid tissue in the
human body.
AIDS
Å
It refers to the deficiency of the immune system, acquired
during the life-time of an individual, indicating that it is not
a congenital disease. It was first reported in 1981 in USA.
Å
The causative agent is Human Immunodeficiency Virus
(HIV). It belongs to the group of viruses called retro virus. It
has single-stranded RNA genome enclosed in an envelope.
Å
These virus particles enter helper T-lymphocytes
(TH cells) in the blood, where they continue to replicate
and produce viral progeny.
Å
The number of helper T-lymphocytes progressively
decreases in the body of the infected people.
Å
As the number of T-cells decrease, immunity also
decreases. As a result, the person cannot produce any
immune response even against common bacteria like
Mycobacterium, parasites like Toxoplasma viruses and
fungi. During this period, person suffers from fever,
diarrhoea and weight loss.
Treatment and Diagnosis
Å
Å
Enzyme Linked Immuno-Sorbent Assay (ELISA) is
used as a diagnostic test for AIDS.
Treatment of AIDS with anti-retroviral drugs is only
partially effective. These can only prolong the life of the
patient, but cannot prevent death.
Prevention of AIDS
Å
As AIDS has no cure, prevention is the best option.
Preventive measures for HIV infection are
n
Å
HIV is transmitted by
Sexual contact with an infected person.
Transfusion of contaminated blood.
Sharing infected needles.
Infected mother to unborn child through placenta.
n
Å
n
n
n
n
n
n
n
Cancer
Å
HIV/AIDS spreads only through body fluids. There is
always a time-lag between the infection and appearance of
AIDS symptoms, i.e. it varies from a few months to many
years (usually 5-10 years).
It is the major cause of death all over the globe. It is
caused by the breakdown of normal regulatory
mechanisms of cell growth.
Å
Normal cells show a property called contact inhibition
by virtue of which contact with other cells inhibits their
uncontrolled growth.
Å
Cancer cells, however lose this property and continue to
divide giving rise to masses of cells called tumours.
Tumours are of two types–benign and malignant.
n
n
n
Mode of HIV Infection
Å
Virus enters the macrophage after entering the body of a
person.
Å
RNA gets replicated to form viral DNA by enzyme reverse
transcriptase.
Å
Viral DNA gets incorporated into the host cell DNA and
directs the infected cells to produce viruses.
Å
Discouraging unsafe sex and encouraging regular
checkups.
Individuals who are susceptible to infection are
Drug addicts due to intravenous drug injections.
Involved with multiple sexual partners.
Require repeated blood transfusion.
Children born to HIV positive mother.
n
Å
Role of WHO to prevent HIV infection.
Making blood (from blood banks) safe from HIV.
Ensure use of disposable syringes and needles.
Ensure keeping blood banks safe from HIV.
Free distribution of condoms.
Prevention of drug abuse.
n
n
Å
National AIDS Control Organisation (NACO) (1991)
and other NGOs educate peoples about AIDS.
Macrophages continue to produce virus particles and act like
HIV factory.
Å
n
n
Benign tumours normally remain confined to their
original location and do not spread to other parts of
the body and cause little damage.
Malignant tumours are a mass of proliferating cells
called neoplastic or tumour cells. These cells grow
very rapidly, invading and damaging the
surrounding normal tissues.
NEET
KEY NOTES
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194
n
n
As these cells actively divide and grow, these also
starve the normal cells by competing for vital
nutrients.
Cells sloughed from malignant tumours reach distant
sites through blood and wherever they get lodged in
the body, they start a new tumour there. This property
is called metastasis.
Causes of Cancer
Carcinogens are cancer-causing agents. These are
n
n
n
Å
Drugs and Alcohol Abuse
The use of drugs and alcohol has risen especially among the
youth. This is a cause of concern as it results in many harmful
effects. The drugs which are commonly abused are as follows
Å
Chemicals Cigarette smoke (cause lung cancer)
benzopyrene, dyes, paints, etc.
Biological Oncogenic viruses, some parasites, etc.
Cancer causing viruses called oncogenic viruses have
genes called viral oncogenes. Normal cells have genes
called cellular oncogenes (C-one) or proto-oncogenes
which are present in inactive state, but under certain
conditions (like mutation) get transferred to
cancer-causing oncogenes.
n
n
n
Å
Cancer can be detected by the following methods
Å
Blood and bone marrow tests to know number of cell
counts.
Å
Biopsy of a piece of suspected tissue done by cutting in
thin sections, stained and examined under microscope.
Å
Radiography by X-rays to detect cancer of the internal
organs.
Å
Computed tomography using X-rays to generate a 3D
image of internal tissue.
Å
Resonance imaging involves use of non-ionizing
radiation and strong magnetic field to detect pathological
and physiological changes in living tissue.
Å
Monoclonal antibodies against cancer-specific antigens
are also used for cancer detection.
Å
Treatment of cancer involves the following methods
Å
Surgery Tumours are removed by surgery to check
further spread of cancer cells.
Å
Radiation therapy Tumour cells are irradiated by a lethal
dose of radiation by protecting the surrounding normal
cells.
Å
Chemotherapy Several chemotherapeutic drugs are used
to kill cancer cells. But, their side effects like hair loss,
anaemia is also reported.
NEET
Heroine is obtained from the acetylation of morphine,
which is extracted from the latex of poppy plant,
Papaver somniferum.
It is taken either by snorting or through injection.
Heroine is a depressant which slows down the body
functions.
Morphine is an effective sedative, pain killer and very
useful in patients who have undergone surgery.
Cannabinoids are a group of chemicals which interact with
cannabinoid receptors present mainly in brain.
Cannabinoids are obtained from the inflorescence of the
plant Cannabis sativa.
Leaves, flower tops, resins of C. sativa in various
combinations produce hashish, charas, marijuana and
ganja.
These are inhaled or ingested orally.
n
n
n
These drugs affect cardiovascular system of the body.
Coca alkaloids or Cocaine has a potent stimulating action
on the central nervous system, producing a sense of
euphoria and increased energy.
n
Å
n
n
Molecular biology technique to detect genes in
individual with inherited susceptibility to certain cancers.
Treatment of Cancer
Opioids are the drugs which binds to specific opioid
receptors present in our central nervous system and
gastrointestinal tract.
Heroin is a common opioid and is also called as smack. It is
chemically diacetylmorphine, white, odourless, bitter
crystalline compound.
n
Physical Ionizing radiation like X-rays and γ-rays,
non-ionizing radiations like UV-rays (cause DNA
damage leading to neoplastic transformation).
Cancer Detection and Diagnosis
Immunotherapy biological modifiers like α-interferons are
used to activate the immune system and help in destroying
the tumour.
n
Å
Cocaine is derived from the leaves and young branches
of a South American plant called Erythroxylum coca.
Its mode of intake is either sniffting or snorting.
It is a strong stimulant and when taken in overdose
causes headache, convulsions, hallucination and death
due to cardiovascular or respiratory failure.
Hallucinogens are psychedelic drugs because of their effect
on the cerebrum and sense organs.
n
n
n
These are obtained from plants like Atropa belladonna and
Datura species.
Lysergic acid diethyl amide (LSD) is derived from the
fungus Claviceps purpurea.
Effect of these drugs occurs on thoughts, feelings and
perceptions of an individual. Drugs like barbiturates,
comphetamines, benzodiazepines, etc., normally used as
medicines.
KEY NOTES
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CHAPTER 08 > Human Health and Diseases
Å
Tobacco contains nicotine which stimulates the adrenal
gland to release adrenaline and nor-adrenaline which in turn
increases the blood pressure and heart rate.
n
n
n
n
Addiction and Dependence
Å
Addiction is the psychological attachment to certain
effects-such as euphoria and a temporary feeling of
well-being associated with drugs and alcohol.
Å
Dependence on drug/alcohol is the tendency of the body to
manifest a characteristic and unpleasant withdrawl
syndrome, if regular dose of drugs/alcohol is discontinued
abruptly. Withdrawl symptoms are characterised by anxiety,
shakiness, nausea and sweating.
It is obtained from tobacco plant.
Its mode of intake is smoking, chewing or can be used as
a snuff.
Tobacco can induce lung cancer, bronchitis, emphysema,
coronary heart disease, cancer of throat, oral cancer,
urinary bladder cancer, etc.
Smoking of tobacco leads to increase in carbon monoxide
content of blood and reduces the concentration of
haem-bound oxygen. This leads to oxygen deficiency in
the body.
Adolescence and Drug/Alcohol
Abuse
Adolescence is the period during which a child becomes
mature in terms of his/her attitudes and beliefs for
independent participation in the society.
Å
Age between 12-18 years is called adolescent period.
Å
Adolescence is accompanied by several biological and
behavioural changes. It is a vulnerable phase of mental and
psychological developemnt of an individual.
Å
In this age use of drugs or alcohol occurs out of curosity or
experimentation which later turns to addiction.
Effects of Drug/Alcohol Abuse
The common warning signals of drug/alcohol addiction are
Å Drop in academic performance.
Å Isolation from family and friends.
Å Lack of interest in personal hygiene.
Å Aggressive and rebellious behaviour.
Å Reckless behaviour, vandalism and violence.
Prevention and Control
The preventive measures are
Å Avoid undue peer pressure.
Å Accept failures and disappointments as part of life.
Å Seek help from parents and peers.
Å Seek professional and medical help for deaddiction.
Å Look for danger signs.
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1
~ Human Health and Common Diseases in Humans
1 Which of the following adversely affects human
health?
(a) Change in lifestyle
(c) Rest and exercise
(b) Genetic disorders
(d) Both (a) and (b)
2 Health is a combination of
I. physical fitness
II. presence of disease
III. mental and social well-being
Which of the options given above are correct?
(a) I and II
(c) II and III
(b) I and III
(d) I, II and III
3 Human health cannot be maintained by
(a)
(b)
(c)
(d)
maintaining personal hygiene
consuming a diet rich in carbohydrate only
regular physical exercise
None of the above
4 Necessary steps for achieving good health are
I. awareness about diseases.
II. vaccination.
III. proper disposal of wastes.
The correct combination having necessary steps are
(a) I, II and III
(c) I, III and IV
(b) II, III and IV
(d) II and IV
5 Measures for personal hygiene include.
(a)
(b)
(c)
(d)
Intake of clean drinking water
Keeping the body clean
Disinfection of water resources
Both (a) and (b)
6 A disease which can easily transmit from one person
to another is called
(a) non-infectious disease (b) infectious disease
(d) bacterial disease
(c) viral disease
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7 Which one of the following disease is non-infectious
15 Which of the following sets of diseases are caused by
as well as the major cause of death in humans?
bacteria?
(a) Cancer
(c) Asthma
(a) Cholera and tetanus
(c) Tetanus and mumps
(b) AIDS
(d) Typhoid
8 Identify the correct pair representing the causative
agent of typhoid fever and the confirmatory test for
typhoid.
NEET 2019
(a) Streptococcus pneumoniae/Widal test
(b) Salmonella typhi/Anthrone test
(c) Salmonella typhi/Widal test
(d) Plasmodium vivax/UTI test
9 Salmonella typhi generally enters the small intestine
through .......A......... and migrates to other body parts
through ........B........ .
The most appropriate combination to fill the blanks is
(a)
(b)
(c)
(d)
A–contaminated food and water; B–blood
A–contaminated food; B–blood
A–skin; B–blood
A–air; B–blood
10 Common symptoms of typhoid are
(a)
(b)
(c)
(d)
high fever 39°C to 40°C and weakness
stomach pain and constipation
headache and loss of appetite
All of the above
11 The name of Mary Mallon is related with the disease
(a) typhoid
(c) dengue
(b) pneumonia
(d) AIDS
12 Pneumonia is an infection of the ......A...... . The most
common cause of pneumonia is a type of bacteria
known as .....B.... and .....C....... .
Most suitable combination to fill the blanks is
(a) A–liver, B– Salmonella typhi, C–Streptococcus
pneumoniae
(b) A–lungs, B–Streptococcus pneumoniae,
C–Haemophilus influenzae
(c) A–blood, B–Streptococcus pneumoniae,
C–Haemophilus influenzae
(d) A–heart, B–Salmonella typhi, C–Haemophilus
influenzae
13 Which of the following health disorder includes
symptoms of fever, chills, cough, headache, grey to
bluish lips and fingers nails?
(a) Filariasis
(c) Pneumonia
(b) Typhoid
(d) Malaria
14 Infection of pneumonia occurs due to
(a) droplets released from an infected person
(b) released droplets/aerosols inhaled by healthy person
(c) sharing contaminated objects such as glasses and
utensils with an infected person
(d) All of the above
NEET 2016
(b) Typhoid and smallpox
(d) Herpes and influenza
16 Rhinovirus causes
(a) common cold
(c) AIDS
(b) malaria
(d) pneumonia
17 Common cold differs from pneumonia in, that
CBSE-AIPMT 2012
(a) pneumonia is a communicable disease, whereas the
common cold is a nutritional deficiency disease
(b) pneumonia can be prevented by a live attenuated
bacterial vaccine, whereas the common cold has no
effective vaccine
(c) pneumonia is caused by a virus, while the common cold
is caused by the bacterium Haemophilus influenzae
(d) pneumonia pathogen infects alveoli whereas the
common cold affects nose and respiratory passage but
not the lungs
18 Which of the following viruses is not transferred
through semen of an infected male? CBSE-AIPMT 2015
(a)
(b)
(c)
(d)
Hepatitis-B virus
Human immunodeficiency virus
Chikungunya virus
Ebola virus
19 Female Anopheles mosquito is a vector of
(a) filariasis
(c) typhoid
(b) malaria
(d) AIDS
20 Malaria is caused by
(a) Plasmodium vivax
(b) Plasmodium malariae
(c) Plasmodium falciparum
(d) All of the above
21 Malignant malaria is caused by
(a) Plasmodium falciparum (b) Plasmodium ovale
(c) Plasmodium vivax
(d) Plasmodium malariae
22 Where will you look for the sporozoites of the
malarial parasite?
(a) RBCs of humans suffering from malaria
(b) Spleen of infected person
(c) Salivary glands of freshly moulted female Anopheles
mosquito
(d) Saliva of infected female Anopheles mosquito
23 Infective stage of Plasmodium for man is
(a) merozoites
(c) sporozoites
(b) ookinetes
(d) None of these
24 Which of the following toxic substances is
responsible for the high malarial fever?
(a) Haemoglobin
(c) Haemozoin
(b) Haemocyanin
(d) Haemoriden
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CHAPTER 08 > Human Health and Diseases
25 Plasmodium completes its life cycle in two hosts.
Asexual phase in …… host and sexual phase in
…… host.
The correct option with words to fill the blanks is
(a)
(b)
(c)
(d)
human; Culex mosquito
human; female Anopheles mosquito
human; Aedes mosquito
human; male Anopheles mosquito
(a) Plasmodium
(c) houseflies
(a) large intestine
(c) lungs
(b) Entamoeba histolytica
(d) contaminated food and water
(b) liver
(d) kidney
31 Which one is not a symptom of disease caused by
E. histolytica ?
(b) male Culex
(d) female Anopheles
27 Study the given diagram and name the labelled A, B,
C and D.
(a)
(b)
(c)
(d)
Stools with excess mucus and blood clots
Constipation smacked
Abdominal pain and cramps
Nasal discharge
32 Which of the following is a protozoan disease?
When the mosquito
bites another human,
sporozoites are
injected with bite.
Mature infective stages
(sporozoites)
escape from
gut and
migrate to the
mosquito
salivary
glands.
organism
30 Entamoeba histolytica is a parasite of
26 The primary host of Plasmodium is
(a) man
(c) sheep
29 Amoebiasis (amoebic dysentery) is caused by
(a) Malaria
(c) Sleeping sickness
(b) Amoebiasis
(d) All of these
33 Which of the following disease is caused by a
protozoan?
(a) Syphilis
(c) Babesiosis
Sporozoites
Salivary glands
(A)
CBSE-AIPMT 2015
(b) Influenza
(d) Blastomycosis
34 Which of the following endoparasites of humans does
show viviparity?
(D)
Female
mosquito
takes up
gametocytes
with blood
meal.
Mosquito Host
es
cyt
Human
Host
The parasite
reproduces asexually
in liver cells, bursting
the cell and releasing
into the blood.
to
me
Ga
ascariasis and filariasis, respectively.
Male
(C)
(a) A–Sporozoites in spleen, B–Sexual reproduction of
Plasmodium in RBC, C–Gametocytes in RBC,
D–Fertilisation of gametocytes in mosquito’s intestine
(b) A–Sporozoites in liver, B–Asexual reproduction of
Plasmodium in RBC, C–Gametocytes in RBC,
D–Fertilisation of gametocytes in mosquito’s intestine
(gut)
(c) A–Sporozoites in liver, B–Asexual reproduction of
Plasmodium in RBC, C–Gametocytes in RBC,
D–Fertilisation of gametocytes in mosquito’s salivary
glands
(d) A–Sporozoites in kidney, B–Sexual reproduction of
Plasmodium in RBC, C–Gametocytes in RBC,
D–Fertilisation of gametocytes in mosquito’s intestine
28 Which one of the following diseases is spread by
(a)
(b)
(c)
(d)
Dengue fever
Encephalitis
Filariasis
Amoebiasis
CBSE-AIPMT 2015
Ancylostoma duodenale
Enterobius vermicularis
Trichinella spiralis
Ascaris lumbricoides
35 Give the name of two helminths, which cause
Female
(B)
housefly?
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
Ascaris and Wuchereria
Wuchereria and Ascaris
Roundworm and flatworm
Plasmodium and Wuchereria
36 Which of the following diseases causes internal
bleeding, muscular pain, fever, anaemia and blockage
of the intestinal passage?
(a) Ascariasis
(c) Amoebiasis
(b) Filariasis
(d) Trypanosomiasis
37 Infection of Ascaris usually occurs by
(a)
(b)
(c)
(d)
NEET 2013
drinking water containing egg of Ascaris
eating imperfectly cooked pork
tse-tse fly
mosquito bite
38 Elephantiasis, a chronic inflammation that results in
gross deformities is caused by
(a) Trichophyton
(c) E. coli
(b) Wuchereria
(d) Ascaris
39 Elephantiasis causing organism belongs to
(a) Aschelminthes
(c) Cnidaria
(b) Platyhelminthes
(d) Porifera
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198
40 The filariasis pathogen is transmitted to a healthy
person through the bite of
(a)
(b)
(c)
(d)
female Anopheles mosquito
female Aedes mosquito
female Culex mosquito
None of the above
41 Adults of Wuchereria bancrofti attack
(a) excretory system
(c) lymphatic system
AIIMS 2018
(b) digestive system
(d) nervous system
42 In which disease does mosquito transmitted pathogen
cause chronic inflammation of lymphatic vessels?
NEET 2018
(a) Ringworm disease
(c) Elephantiasis
(b) Ascariasis
(d) Amoebiasis
43 Which one of the following pairs is not correctly
(a) Filariasis — Wuchereria
(b) Syphilis — Trichuris trichiura
(c) Plague — Yersinia pestis
(d) Dengue fever — Flavi-ribo virus
44 The group of diseases carried (transmitted) by
insects are
typhoid, jaundice, tuberculosis
mumps, measles, smallpox
scabies, ringworm, swine flu
malaria, filaria, yellow fever
45 The following table shows certain diseases, their
causative organisms and symptoms.
Diseases
Causative
organisms
Symptoms
I. Filariasis
A
Inflammation of lymphatic
vessels
II. Typhoid
B
High fever, stomach pain
III.
C
IV. Ascariasis
Rhinoviruses
Nasal congestion and discharge
Ascaris
46 Fungi belonging to genera–Microsporum,
Trichophyton and Epidermophyton are responsible for
(a)
(b)
(c)
(d)
ringworm infection
skin allergy
amoebiasis
measles
47 Ringworm is a/an
(a) air borne disease
(b) infectious disease
(c) non-infectious disease (d) None of these
matched?
(a)
(b)
(c)
(d)
The correct option regarding A, B , C and D is
(a) A–Wuchereria, B–Salmonella typhi, C–Common cold,
D–Internal bleeding, fever, anaemia
(b) A–Salmonella typhi, B–Ascaris, C–Typhoid,
D–Stomach pain, headache
(c) A–Ascaris, B–Entamoeba histolytica, C–Pneumonia,
D–Constipation, fever
(d) A–Entamoeba histolytica, B–Salmonella typhi,
C–Common cold, D–Nasal discharge, high fever
D
48 Fill up the blanks.
I. Heat and moisture help ............ fungi to grow, which
makes them thrive in skin folds.
II. Maintenance of ............ and ............ hygiene is
important for the prevention of many infectious
diseases.
III. ............ gives the diseases its name, elephantiasis.
(a) I. Microsporum, II. public; personal, III. Swelling of
hand
(b) I. Trichophyton, II. personal; public, III. Enlargement
of eye
(c) I. Epidermophyton, II. personal; public,
III. Swelling of legs
(d) I. Wuchereria, II. personal; public; III. Enlargement of
tongue
49 Gambusia is a fish which can control the mosquito
borne disease like
(a) dengue
(c) chikungunya
(b) malaria
(d) All of these
TOPIC 2 ~ Immunity
50 Ability of the body to fight against the disease
causing organisms is called
(a) vulnerability
(c) irritability
(b) susceptibility
(d) immunity
51 Innate immunity is also called
(a) familiar immunity
(c) genetic immunity
(b) inborn immunity
(d) All of these
52 Non-specific host defence that exists prior to the
exposure to an antigen is called
(a) acquired immunity
(c) innate immunity
(b) passive immunity
(d) active immunity
53 Except skin, other physical barriers which also help to
prevent the entry of the microorganisms are mucus
coating of the epithelium lining of
I. the respiratory tract.
II. the gastrointestinal tract.
III. the urogenital tract.
Choose the correct option.
(a)
(b)
(c)
(d)
I and II
I and III
II and III
I, II and III
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CHAPTER 08 > Human Health and Diseases
54 Which type of barriers do saliva in the mouth, tears
form eyes and acid in the stomach belong?
(a) Cytokinin barriers
(b) Cellular barriers
(c) Physiological barriers (d) Physical barriers
55 Full form of PMNL is
(a)
(b)
(c)
(d)
Poly Morpho-Nuclear Leucocytes
Para Morpho-Nuclear Lymphocytes
Penta Morpho-Nuclear Leucocytes
Poly Morpho-Nuclear Lymphocytes
(b) antigen
(d) macrophages
57 Which of the following are considered as cellular
barrier of the body?
(a) Lymphocytes
(c) Macrophages
(a) proteins produced in response to pathogens in our
body
(b) secreted by the action of both T-lymphocytes and
B-lymphocytes
(c) molecules that specifically interacts with an antigen
(d) Both (a) and (b)
65 Each antibody has ...A... polypeptide chains, ..B..
56 The major phagocytic cells are
(a) antibody
(c) lymphocytes
64 Antibodies are
(b) Neutrophils
(d) All of these
58 Humans have acquired immune system that produces
antibodies to neutralise pathogens. Still innate
immune system is present at the time of birth because
NEET (Odisha) 2019
it
(a) is very specific and uses different macrophages
(b) produces memory cells for mounting fast secondary
response
(c) has natural killer cells which can phagocytose and
destroy microbes
(d) provides passive immunity
small chains called ...C... chains and ....D... longer
chains called ...E... chains.
The antibody, therefore, is represented as ... F..
Here A to F refers to
(a)
(b)
(c)
(d)
A–four, B–two, C–light, D–two, E–heavy, F–H 2 L 2
A–six, B–three, C–light, D–three, E–heavy, F–H 3 L 2
A–two, B–one, C–light, D–one, E–heavy, F–H 1 L1
A–five, B–two, C–light, D–three, E–heavy, F–H 2 L 2
66 Antigen binding site of immunoglobulin (antibody) is
(a)
(b)
(c)
(d)
variable region of heavy chain
variable region of light chain
constant region of light chain
variable region of both heavy and light chain
67 The figure given below shows an antibody molecule.
Name the parts A, B and C.
A
s
59 Which of the following is a suitable example of
cytokine barrier?
(a) Interferons
(c) B-lymphocytes
(b) T-lymphocytes
(d) T H cells
s
s
C
60 The interferons can be used as
(a) antibacterial drugs
(c) antibiotic drugs
s
s
s
s
s
s
B
homeostatic disorder
hepatitis caused by virus
common cold caused by virus
Both (b) and (c)
(a) typhoid
(b) filariasis
(c) malaria
63 Note the following words.
I. Skin
II.
III. B-cells
IV.
V. Antibodies
VI.
VII. Macrophages
VIII.
(d) measles
Phagocytes
Neutrophils
T-cells
NK-cells
Identify the factors involved in second line of defence.
(a) II, IV, VII and VIII
(c) IV, VI, VIII and VIII
(b) II, III, V and VI
(d) III, V, VII and VIII
s
s
s
ss
ss
counter
seems to carry an infection of
s
ss
ss
(b) antiviral drugs
(d) immunosuppressive
62 A person has developed interferons in his body. He
s
s
61 Interferon is a type of protein, which can be used to
(a)
(b)
(c)
(d)
s
s
s
s
s
D
ss
ss
ss
(a) A–Antigen binding site, B–Heavy chain, C–Light chain,
D–Disulphide bond
(b) A–Antibody binding site, B–Light chain, C–Heavy
chain, D–Phosphoester bond
(c) A–Antigen binding site, B–Short chain, C–Long chain,
D–Sulphur bond
(d) A–Antibody binding site, B–Long chain, C–Short
chain, D–Disulphide bond
68 The most abundant class of Immunoglobulins (Igs) in
the human body is
(a) IgA
(c) IgG
(b) IgM
(d) IgE
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Master The NCERT > Biology (Vol-II )
200
80 Choose the correct option regarding antibodies.
69 Humoral immunity is also called as
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
antibody mediated immunity
non-specific immune response
antigen mediated immunity
None of the above
70 Humoral immunity is mediated by
(a) B-cells
(c) macrophages
81 The principle of vaccination or immunisation depends
(b) T-cells
(d) monocytes
on the property of ..... of the immune system. The
most appropriate word to fill the blank is
71 Humoral immune system defends against viruses and
bacteria is present in
(a) blood
(c) Both (a) and (b)
(b) lymph
(d) None of these
carried out by
(a) memory
(c) pathogen
(b) antigen
(d) plasma cells
82 Which form of pathogen is used in vaccination?
72 The cell-mediated immunity inside the human body is
(a) T-lymphocytes
(c) thrombocytes
JIPMER 2019
IgA - Helps in allergic reaction
IgG - Cross placenta
IgE - Found in secretions
IgM - Exist as dimer
NEET 2013
(b) B-lymphocytes
(d) erythrocytes
(a) Activated and strong pathogens
(b) Preformed antigens and antibody
(c) Inactivated and weakened pathogenic agents
(d) None of the above
83 If a quick immune response is needed as in tetanus
damaged tissues or organs like heart, eye, liver,
kidney with healthy ones from a donor is called as
infection, preformed antibodies or antitoxin is
injected into the patient body. This type of
immunisation is called ……… .
(a) transplantation
(b) repair and replacement
(c) replacement theraphy (d) transformation
(a) active immunisation
(c) innate immunity
73 The process of removal and replacement of the
74 Which of the following immune responses is
responsible for rejection of kidney graft?
NEET 2019, CBSE-AIPMT 2015
(a)
(b)
(c)
(d)
Humoral immune response
Inflammatory immune response
Cell-mediated immune response
Auto-immune response
(b) exposure to live pathogen
(d) Both (a) and (b)
(b) memory cells
(d) suppressor T-cells
(a) transfer of lymphocyte directly
(b) transfer of maternal antibodies across placenta to the
foetus
(c) introduction of antibodies directly in the body
(d) Both (b) and (c)
78 Colostrum, the yellowish fluid, secreted by mother
during the initial days of lactation is very essential to
impart immunity to the new born infants because it
contains
NEET 2019
(b) macrophages
(d) natural killer cells
79 Which of the following is involved in passive
immunity?
(a) IgA
(c) IgM
JIPMER 2018
(b) IgE
(d) IgD
(b) gamma globulin
(d) activated pathogens
(a) yeast
(c) bacteria
(b) bacteriophage
(d) All of these
86 A substance that causes an allergic reaction is called
(a) allergen
(c) foreign substance
(b) pollen
(d) dander
87 Which of the following mediates allergic reaction?
JIPMER 2018
77 Passive immunisation includes
(a) monocytes
(c) immunoglobulin-A
while polio drops that are administered into the body
NEET 2016
contain
85 Hepatitis-B vaccine is produced from
76 Active immunity development is related to
(a) natural killer cells
(c) helper T-cells
84 Antivenom injection contains preformed antibodies
(a) harvested antibodies
(c) attenuated pathogens
75 Active immunity is an immunity gained after
(a) natural infection
(c) immunisation
(b) passive immunisation
(d) humoral immunity
(a) IgA
(b) IgG
(c) IgE
(d) IgD
88 Common examples of allergens are
(a) dust
(c) animal dander
(b) pollen grains
(d) All of these
89 An allergic response appears at the site of infection
causes sneezing, watery eyes, running nose, pain and
heat due to the certain chemicals (allergens), they are
(a) histamine and serotonin (b) histamine and cerumen
(c) cerumen and serotonin (d) mucus and cerumen
90 What is injected into the patient’s body for
determining the cause of allergy?
(a)
(b)
(c)
(d)
Allergen to which the patient is allergic
IgG
IgE
Steroids
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CHAPTER 08 > Human Health and Diseases
91 Which of the following drugs can be used to quickly
reduce the symptoms of allergic reaction?
I. Anti-histamine
II. Adrenaline
III. Steroids
(a) I and II
(c) II and III
and beneath the ....B.... . The most appropriate
combination for A and B is
(a)
(b)
(c)
(d)
(b) I and III
(d) I, II and III
92 Asthma may be attributed to
NEET 2016
(a) allergic reaction of the mast cells in the lungs
(b) inflammation of the trachea
(c) accumulation of fluid in the lungs
(d) bacterial infection of the lungs
93 In higher vertebrates, the immune system can
distinguish self and non-self cells. If this property is
lost due to the genetic abnormality and it attacks
self-cells, then it leads to
NEET 2016
(a) graft rejection
(b) autoimmune disease
(c) active immunity
(d) allergic response
disorder?
NEET (Odisha) 2019
(b) Arthritis
(d) Gout
95 Which of the following is not an autoimmune
disease?
(a)
(b)
(c)
(d)
A–heart; B–breast bone
A–liver; B–ribs
A–heart; B–ribs
A–intestine; B–ribs
100 What is the main lymphoid organ where all blood
cells including lymphocytes are produced?
(a) Bone marrow
(c) Liver
(b) Tonsils
(d) Spleen
101 T-lymphocytes mature in the ........... while
B-lymphocyte mature in the ........ .
Most appropriate combination of words to fill the
blanks is
(a)
(b)
(c)
(d)
thymus; bone marrow
bone marrow; thymus
thyroid; bone marrow
yellow bone marrow; red bone marrow
102 Full form of MALT is
94 Which of the following diseases is an autoimmune
(a) Myasthenia gravis
(c) Osteoporosis
99 Thymus is a lobed organ located near the...... A .....
NEET 2018
(a)
(b)
(c)
(d)
Mucosal Associated Lymphoid Tissue
Memory Associated Lymphoid Tissue
Memory Associated Lymphocyte Tissue
Mucosa Associated Lymphocyte Tissue
103 MALT constitutes about ...…… per cent of the
lymphoid tissue in human body.
(a) 50%
(c) 70%
Alzheimer’s disease
Rheumatoid arthritis
Psoriasis
Vitiligo
NEET 2017
(b) 20%
(d) 10%
104 Given below the diagrammatic representation of
lymph nodes.
96 The site where immature lymphocytes differentiate
into antigen sensitive lymphocytes are
(a)
(b)
(c)
(d)
primary lymphoid organs
secondary lymphoid organs
lymph nodes
tonsils
A
B
97 Which of the given sets include the primary lymphoid
organs?
(a)
(b)
(c)
(d)
Thymus, lymph nodes and spleen
Bone marrow and thymus
Bone marrow, Peyer’s patches and thymus
Thymus, liver and tonsils
98 Surgical removal of thymus of a newborn shall result
in the failure to produce
(a) Allergens
(c) B-lymphocyte
(b) Interferons
(d) T-lymphocytes
C
Label A, B and C.
(a)
(b)
(c)
(d)
A–Lymph nodes, B–Thymus, C–Lymphatic vessels
A–Lymphatic vessels, B–Thyroid, C–Lymph nodes
A–Tonsils, B–Peyer’s patchs, C–Lymphatic vessels
A–Tonsils, B–Thymus, C–Peyer’s patches
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TOPIC 3 ~ AIDS (Acquired Immuno Deficiency Syndrome)
(a) A–Bacteriophage, B–Viral DNA is produced, C–New
viral RNA is produced
105 Human immunodeficiency virus causes
(a)
(b)
(c)
(d)
Acquired Immuno Deficiency Syndrome
Anthrax
tuberculosis
polio
106 Genetic material found in Human Immunodeficiency
Virus (HIV) is
(a)
(b)
(c)
(d)
double-stranded RNA
single-stranded RNA
double-stranded DNA
single-stranded DNA
110 HIV is a ....A...... and has genetic material composed of
107 AIDS virus contains
(a)
(b)
(c)
(d)
(b) A–Transcriptase, B–Bacterial RNA is produced, C–New
viral DNA is produced by the infected cell
(c) A–Bacteriophage, B–Viral DNA is produced, C–New
viral RNA is produced by the infected cell
(d) A–Retrovirus, B–Viral DNA is produced by reverse
transcriptase, C–New viral RNA is produced by the
infected cell
...B...., HIV replicates inside the host cells. It is
considered a retrovirus because it uses an enzyme,
....C.... , to convert ...... D...... into .......E...... . Here
A to E refers to
RNA with protein
DNA with protein
RNA without protein
Only DNA
108 Transmission of HIV infection from infected mother
to her child occurs through
(a) liver
(b) placenta
(c) skin
(d) None of these
109 In the given flow chart, the replication of retrovirus
in a host cell is shown. Observe it carefully and fill
up the blank A, B and C.
(A)
(a) A–retrovirus, B–RNA, C–reverse transcriptase,
D–RNA, E–DNA
(b) A–retroviral, B–DNA, C–reverse transcriptase,
D–DNA, E–RNA
(c) A–rhinovirus, B–DNA, C–reverse transcriptase,
D–DNA, E–RNA
(d) A–adenovirus, B–RNA, C–reverse transcriptase,
D–RNA, E–DNA
111 In an infected human body the ‘HIV factory’ is
(a) sperm
(c) macrophages
(b) ova
(d) spleen cells
112 At which stage of HIV infection does one usually
Virus infects
normal cell
Plasma
membrane
Animal cell
(B)
Cytoplasm
Viral DNA incorporates
into host genome
show symptoms of AIDS?
CBSE-AIPMT 2014
(a) Within 15 days of sexual contact with an infected person
(b) When the infected retrovirus enters host cells
(c) When HIV damages large number of helper
T-lymphocytes
(d) When the viral DNA is produced by reverse transcriptase
113 A patient is suspected to be suffering from Acquired
Immuno Deficiency Syndrome (AIDS). Which
diagnostic technique will you recommend for its
detection?
(C)
(a) ELISA
Nucleus
DNA
(b) MRT
(c) Ultrasound (d) WIDAL
114 The word NACO stands for
(a)
(b)
(c)
(d)
National AIDS Control Organisation
Non-governmental AIDS Control Organisation
National Agrochemical Organistation
Both (b) and (c)
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203
CHAPTER 08 > Human Health and Diseases
TOPIC 4 ~ Cancer
115 The property of normal cells by virtue of which
contact with other cells inhibits their uncontrolled
growth is called
(a) contact inhibition
(c) benign tumour
(b) metastasis
(d) metagenesis
116 Cell division or mitosis is a normal process in living
cells but sudden and abnormal mitosis in an organ
will frequently result in
(a) zygote
(c) new organ
(b) cancer
(d) gastrula
117 The uncontrolled proliferation of cancerous cells
produces masses of cells, called
(a) tumours
(c) protooncomass
(b) neoplastic cells
(d) Both (a) and (b)
118 Which form of tumour remains confined to their
original location and do not spread to other parts of
the body?
(a) Malignant tumour
(c) Both (a) and (b)
(b) Benign tumour
(d) Leukaemia
119 Which of the following properties is possessed by
malignant tumours?
(a)
(b)
(c)
(d)
Metastasis
Uncontrolled cell division
Both (a) and (b)
Controlled cell division
cancerous cells, whereas the remaining three are?
CBSE-AIPMT 2012
(a) They compete with normal cells for vital nutrients
(b) They do not remain confined in the area of formation
(c) They divide in an uncontrolled manner
(d) They show contact inhibition
121 Transformation of normal cell into cancerous cell is
induced by
(b) lipids
(d) All of these
122 Physical carcinogens, e.g. UV-ray, X-ray and γ-rays
cause
(a) DNA damage
(c) Both (a) and (b)
(b) RNA damage
(d) Protein damage
123 Chemical carcinogens present in tobacco smoke have
been identified as a major cause of
(a) lung cancer
(c) oral cancer
(a) oncogenic viruses
(c) adenoviruses
(b) retroviruses
(d) poxviruses
125 The genes which can lead to the oncogenic
transformation of the cells in which these are present,
are called
(a) oncogenes
(c) cellular oncogenes
(b) proto-oncogenes
(d) Both (b) and (c)
126 Normal cell have genes called ........A..... which are
present in inactivated state but under certain
conditions like .....B... they get transformed to ...C....
Here A, B and C refers to
(a) A–cellular oncogenes, B–mutation, C–cancer causing
oncogenes
(b) A–viral oncogenes, B–mutation, C–disease causing
genes
(c) A–viral oncogenes, B–mutation, C–tumour causing
genes
(d) None of the above
127 Characteristics of cancer are
(a)
(b)
(c)
(d)
AIIMS 2018
All viruses are oncogenic
All tumours are cancers
Cancerous cells show property of contact inhibition
Cancer cells show metastasis
128 Which of the following techniques is used to detect
120 Which one of the following is not a property of
(a) carcinogens
(c) proteins
124 Cancer causing viruses are called
(b) liver cancer
(d) None of these
the of cancer of internal organs?
(a)
(b)
(c)
(d)
Magnetic Resonance Imaging (MRI)
Radiography (X-ray)
Computed Tomography (CT) scan
All of the above
129 Cancer cells are more easily damaged by radiation
than normal cells because they are
(a)
(b)
(c)
(d)
starved of mutation
undergoing rapid division
different in structure
non-dividing
130 Treatment and detection of cancer can be done by
(a) radiography
(c) surgery
(b) chemotherapy
(d) All of these
131 Alpha-interferons
(a)
(b)
(c)
(d)
activate the immune system
help in destroying the tumour
Both (a) and (b)
None of the above
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204
TOPIC 5 ~ Drug and Alcohol Abuse
132 Opioids are the drugs, which bind to specific opioid
141 Observe the molecules A and B given below and
select the right option giving their use and source.
receptors present in our
HO
(a) central nervous system
(b) gastrointestinal tract
(c) Both (a) and (b)
(d) urinogenital system
OH
O
133 Smack is chemically .....A..... which is white and
odourless and crystalline in nature. This is obtained
by ....B.... . Here A and B refers to
(a)
(b)
(c)
(d)
A–diacetylmorphine; B–acetylation of morphine
A–morphine; B–acetylation of hashish
A–stimulant; B–acetylation of morphine
A–hallucinogen; B–acetylation of hashish
134 Durg called ‘heroin’ is synthesised by
(a)
(b)
(c)
(d)
acetylation of morphine
glycosylation of morphine
nitration of morphine
methylation of morphine
NEET 2019
135 Which part of poppy plant is used to obtain the drug
smack?
(a) Roots
(c) Flowers
NEET 2018
(b) Latex
(d) Leaves
136 A drug called heroin is obtained from
(a)
(b)
(c)
(d)
Rauwolfia serpentina
Cannabis sativa
Cajanus cajan
Papaver somniferum
interact with cannabinoid receptors present
principally in
(a) brain
(c) nephron
(b) neuron
(d) dendron
138 Cannabinoids are obtained from
(a)
(b)
(c)
(d)
HO
B
Cannabinoid
A
Morphine
Molecules
inflorescence of the plant Cannabis sativa
fruits of the plant Papaver somniferum
latex of the plant Cannabis sativa
plant Papaver somniferum inflorescence
Taken by
Uses
(a) A–Morphine
Sedative and pain
killer
(b) B–Morphine
Product marijuana
Oral ingestion
(c) A–Cannabinoid
Produces
hallucinations
inhalation
(d) B–Cannabinoid
Accelerates the
transport of dopamine
injection
Snorting and
injection
142 Coca alkaloid or cocaine is obtained from
NEET (Odisha) 2019
(a) Papaver sonmiferum
(c) Erythoxylum coca
(b) Atropa belladonna
(d) Datura
143 Cocaine is commonly called as
(a) coke
(c) Both (a) and (b)
137 Cannabinoid are the group of chemicals, which
HO
N—CH3
H
(b) crack
(d) smack
144 Traditional anesthesia is obtained from JIPMER 2019
(a) Datura
(b) poppy
(c) Cannabis
(d) Erythoxylum
145 Which one of the following is a stimulant?
(a) LSD
(b) Cocaine (c) Opium
(d) Heroin
146 Plants with hallucinogenic properties are
(a) Atropa belladonna
(c) Both (a) and (b)
(b) Datura
(d) Papaver
147 Identify the pictures A, B and C.
139 The flower tops, leaves and the resin of Cannabis
sativa are used to produce
(a) marijuana
(c) charas
(b) hashish
(d) All of these
140 The drug that produces profound cardiovascular
effects in human beings is
(a) cocaine
(c) benzodiazepine
(b) ganja
(d) insulin
A
(a)
(b)
(c)
(d)
B
C
.
A–Opium poppy, B–Cannabis sativa, C–Datura
A–Cannabis sativa, B–Opium poppy, C–Datura
A–Datura, B–Opium poppy, C–Cannabis sativa
A–Opium poppy, B–Datura, C–Cannabis sativa
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CHAPTER 08 > Human Health and Diseases
148 Which is the particular type of drug that is obtained
from the plant whose one flowering branch is shown
below?
CBSE-AIPMT 2014
156 In heavy smokers, the alveoli of the lungs are
enlarged and damaged, which reduces the surface
area for the exchange of respiratory gases. This
condition is called
(a)
(b)
(c)
(d)
asthma
silicosis
emphysema
insomnia
157 Carcinogen present in cigarette smoke is
(a) benzopyrene
(c) carbon monoxide
(b) nicotine
JIPMER 2019
(d) All of these
158 Those who take drugs intravenously develop a risk of
(a) Hallucinogen
(c) Stimulant
(b) Depressant
(d) Pain killer
149 Drugs, that are normally used as medicines to help the
(a) AIDS
(c) Both (a) and (b)
(b) hepatitis-B
(d) malaria
159 Cirrhosis of liver is caused by the chronic intake of
CBSE-AIPMT 2012
patients cope with mental illness are
(a) barbiturates
(c) benzodiazepines
(b) amphetamines
(d) All of these
150 LSD is derived from
(a) Claviceps purpurea
(c) Cannabis indica
(b) Pseudomonas putida
(d) Cannabis sativa
151 Which one of the following is a correct matching pair
of a drug and its category?
(a)
(b)
(c)
(d)
Amphetamines
Lysergic acid diethylamide
Heroin
Benzodiazepies
— Stimulant
— Narcotic
— Psychotropic drug
— Pain killer
152 Which one of the following fungi contains
hallucinogens?
(a) Morchella esculenta
(c) Neurospora sp.
CBSE-AIPMT 2014
(b) Amanita muscaria
(d) Ustilago sp.
153 Nicotine is
(a) an alkaloid
(c) a stimulant
(b) a steroid
(d) Both (a) and (c)
154 Nicotine intake stimulates the ....A... to release ...B....
and ....C.... into blood circulation. This lead to
increase in ...D... and an increase.... E .... .
Identify A to E.
(a) A–adrenal gland, B–adrenaline, C–nor-adrenaline,
D–blood pressure, E–heart rate
(b) A–thyroid gland, B–thyroxine, C–parathyroxine,
D–blood pressure, E–heart rate
(c) A–adrenal gland, B–thyroxine, C–nor-adrenaline,
D–blood pressure, E–heart rate
(d) A–gonads B–adrenaline, C–nor-adrenaline, D–blood
pressure, E–heart rate
155 Smoking addiction is harmful because smoke produces
polycyclic aromatic hydrocarbons, which cause
(a)
(b)
(c)
(d)
reduction in oxygen transport
increase in blood pressure
cancer
retardation of growth of foetus
(a) opium
(c) tobacco (chewing)
(b) alcohol
(d) cocaine
160 Fill up the blanks.
I. The period between ....A....years of age may be thought
of as adolescence period.
II. Adolescence is a bridge linking ....B .... and ....C....
III. The chronic use of drug and alcohol damages ...D....
and ...E...
IV. Alcoholism during ....F.... adversely affects the foetus.
(a) A–12-18, B–childhood, C–adulthood, D–nervous
system, E–liver, F–pregnancy
(b) A–10-15, B–adulthood, C–childhood, D–heart,
E–stomach, F–adulthood
(c) A–15-20, B–adulthood, C–childhood, D–liver,
E–kidney, F–pregnancy
(d) A–20-28, B–adulthood, C– childhood, D–liver,
E–nervous system, F–pregnancy
161 Which part of the brain is involved in the loss of
control over speech when a person consumes
excessive alcohol?
(a)
(b)
(c)
(d)
Cerebellum
Medulla oblongata
Cerebrum
Pons varoli
162 Side effects of anabolic steroids in females include
I. masculinisation.
II. aggressiveness.
III. mood swings, depression.
IV. abnormal menstrual cycle.
V. excessive facial and body hair.
Choose the correct option.
(a)
(b)
(c)
(d)
I, II and III
I, II, III and IV
II, III, IV and V
I, II, III, IV and V
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Master The NCERT > Biology (Vol-II )
206
NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
171 Assertion (A) Cancer cells are virtually immortal
■ Direction (Q. No. 163-177) In each of the following
questions, a statement of Assertion (A) is given followed
by corresponding statement of Reason (R).
Of the statements, mark the correct answer as
(a) If both A and R are true and R is the correct
explanation of A
(b) If both A and R are true, but R is not the correct
explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true
163 Assertion (A) Escherichia coli, Shigella sp. and
164
165
166
167
168
169
170
Salmonella sp. are all responsible for diarrhoeal
diseases.
Reason (R) Dehydration is common to all types of
diarrhoeal diseases and adequate supply of fluids and
electrolytes should be ensured.
Assertion (A) Interferons help to eliminate the viral
infections.
Reason (R) Interferons released by infected cells,
reach the nearby uninfected cells and make them
resistant to viral infection.
Assertion (A) Interferons are a type of antibodies
produced by body cells infected by bacteria.
Reason (R) Interferons interferes with viral
replication at the site of injury.
Assertion (A) Antibody mediated immune response
is provided by B-cells.
Reason (R) B-cells work chiefly by secreting
substances called antibodies into the body fluids.
Assertion (A) A person who has received a cut and is
bleeding needs to be given anti-tetanus treatment.
Reason (R) Anti-tetanus injection stimulates the
production of antibodies for tetanus.
Assertion (A) Mast cells in the humans release
excessive amount of chemicals like histamine, which
cause allergy.
Reason (R) Allergens in the environment on reaching
human body stimulate mast cells.
Assertion (A) Many visitors of hills suffer from skin
and respiratory allergy problems.
Reason (R) Pinus trees produce a large quantity of
wind-borne pollen grains.
Assertion (A) AIDS is a disorder caused by HIV.
Reason (R) HIV is a virus that damages immune
system of its host.
172
173
174
175
176
177
until the body in which they reside dies.
Reason (R) Cancer is caused by damage to genes
regulation of the cell division cycle.
Assertion (A) Metastasis is the phenomenon in which
tumour cells detach and migrate to other parts of the
body where they give rise to secondary tumours.
Reason (R) Abnormal antigens on the surface of cell
and unusual number of chromosomes cause
metastasis.
Assertion (A) Cannabinoids are known for their
effects on cardiovascular system of the body.
Reason (R) Cannabinoids is a class of diverse
chemical compounds that activates cannabinoid
receptors present principally in brain.
Assertion (A) Alcohol consumption during
pregnancy is harmful.
Reason (R) Alcohol causes physical and mental
defects in the offspring called Foetal Alcohol
Syndrome (FAS).
Assertion (A) Dope test is used to estimate the level
of alcohol by analysing the breathe of alcohol
drinking person.
Reason (R) Athletes undergo dope test before major
tournaments or a match.
Assertion (A) Repeated use of drugs, increases the
tolerance level of receptors in our body.
Reason (R) Addiction occurs as receptors respond
only to higher doses of drugs.
Assertion (A) Pork should be properly cooked to
avoid Taenia infection.
Reason (R) Pork of pig contains hexacanth and
cysticercus larvae.
II. Statement Based Questions
178 Which of the following statement(s) is/are correct
regarding pathogens?
I. A pathogen or an infectious agent is a microorganism,
such as a virus, bacterium, fungus that causes disease
in its host.
II. Pathogens multiply in our body and interfere with the
normal vital activities, resulting in morphological and
functional damage.
(a) Only I
(c) I and II
(b) Only II
(d) None of these
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CHAPTER 08 > Human Health and Diseases
179 Which one of the following statements is correct with
respect to immunity?
CBSE-AIPMT 2012
(a) Preformed antibodies need to be injected to treat the bite
by a viper snake
(b) The antibodies against smallpox pathogen are produced
by T-lymphocytes
(c) Antibodies are protein molecules, each of which has
four light chains
(d) Rejection of a kidney graft is the function of
B-lymphocytes
180 Which of the following is correct regarding AIDS
causative agent HIV?
NEET 2016
(a) HIV is enveloped virus containing one molecule of
single-stranded RNA and one molecule of reverse
transcriptase
(b) HIV is enveloped virus that contains two identical
molecules of single-stranded RNA and two molecules
of reverse transcriptase
(c) HIV is unenveloped retrovirus
(d) HIV does not escape but attacks the acquired immune
response
181 Consider the following statements.
I. Adolescence is a very vulnerable phase of mental and
psychological developments of individual.
II. Adolescence is marked by accelerated physical
growth, development of reproductive organs and
changes in functioning of the neuroendocrine system.
(a)
(b)
(c)
(d)
Both statements I and II are correct
Both statements I and II are incorrect
Statement I is correct, but II is incorrect
Statement I is incorect, but II is correct
182 Choose the correct statements.
I. Innate immunity is accomplished by providing
different types of barriers.
II. Acquired immunity is present from the birth and is
inherited from parents.
III. Acquired immunity can be divided into antibody
mediated and cell-mediated immunity.
IV. Innate immunity is also called specific immunity.
V. Acquired immunity consists of specialised cells
(T-cell and B-cell) and antibodies that circulate in the
blood.
Codes
(a) I, II and V
(c) I, III and V
(b) II, III, IV and V
(d) I, II, III, IV and V
183 Consider the following statements.
I. People should get vaccination to avoid infection.
II. Vaccination is available against polio, cholera,
typhoid, tuberculosis and many other diseases.
III. Eradication of vectors are necessary in diseases like
malaria and filariasis.
IV. Dengue and chikungunya, both are spread by Culex
mosquitoes.
Which of the statements given above are correct?
(a) I, II and III
(c) I, III and IV
(b) I, II and IV
(d) III and IV
184 Which of the following statements given below is/are
correct?
I. Secondary lymphoid organs includes lymph nodes,
spleen and small masses of lymph tissue such as
Peyer’s patches, appendix and tonsils.
II. The secondary lymphoid organs provide the site for
interaction of lymphocyte with the antigens.
(a) Only I
(c) I and II
(b) Only II
(d) None of these
185 The lymph nodes
I. are small solid structures along the lymphatic system.
II. filter lymph fluid as it flows through them, trapping
bacteria, viruses and other antigens, which are then
destroyed by lymphocytes.
Which of the statements given above is/are corrcet?
(a) Only I
(c) I and II
(b) Only II
(d) None of these
186 Read the statements about a certain organ and choose
the correct option.
I. It is a large bean-shaped organ.
II. It mainly contains lymphocytes and phagocytes.
III. It acts as a filter of the blood by trapping blood-borne
microorganisms.
IV. It is a large reservoir of erythrocyte.
V. It is a secondary lymphoid organ.
(a) Thymus (b) Tonsils (c) Appendix
(d) Spleen
187 Select the true statements.
I. Cancer detection is based on biopsy and
histopathological study of the suspected tissue.
II. In biopsy, the suspected tissue is cut into thin sections,
stained and examined under microscope.
III. Certain chemotherapeutic drugs are used to kill the
cancerous cells, but majority of the drugs have side
effects like hair loss, anaemia, etc.
IV. MRI uses strong magnetic fields and ionising
radiations to accurately detect pathological and
physiological changes in the living tissues.
V. Techniques like radiography (use of X-rays), CT
(Computed Tomography) scan and MRI are very
useful to detect cancers of the internal organs.
(a) I and II
(c) II and III
(b) I and III
(d) All statements are true
188 Which of the following statements given below is/are
correct?
I. Growing number of people are taking LSD and other
drugs like barbiturates and amphetamines to help
themselves to cope with mental illness.
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Master The NCERT > Biology (Vol-II )
208
II. Several plants, fruits and seeds having hallucinogenic
properties have been used in folk-medicine.
(a)
(b)
(c)
(d)
Statement I is true, but II is false
Stetement I is false, but II is true
Both statements I and II are true
Both statements I and II are false
189 Warning signs of drug and alcohol abuse include
I. drop in academic performance.
II. absence from school/college.
III. lack of interest in personal hygiene.
IV. isolation, depression, fatigue, aggresssive and
rebellious behaviour.
Which of the statements given above are correct?
(a) I, II and III
(c) II, III and IV
(b) I, III and IV
(d) All of these
190 Reasons for alcohol abuse in adolescents are
I. social pressure.
II. curiosity and need for adventure, excitement and
experiment.
III. to escape from stress, depression and frustration.
IV. to overcome hardships of daily life.
Which of the statements given above are correct?
(a) I, II and III
(c) II, III and IV
(b) I, III and IV
(d) All of these
191 Read the following statements and select the incorrect
one.
(a) When the functioning of one or more organs or systems
of the body is adversely affected, characterised by
appearance of various signs and symptoms, i.e. we have
a disease
(b) Some of the infectious diseases like AIDS are fatal
(c) Pathogens cause harm to the host by living in (or on) them
(d) None of the above
192 Read the following statements and select the correct
statements.
I. Subsequent encounter with the same pathogen for the
second time elicits a highly intensified secondary
immune response.
II. The vaccines generate B and T-cells that recognise the
pathogen quikly on subsequent exposure and
overwhelm the invaders with massive production of
antibodies.
(a)
(b)
(c)
(d)
Both statements I and II are correct
Statement I is correct, but II is incorrect
Statement I is incorrect, but II is correct
Both statements I and II are incorrect
193 Which of the following statements are correct?
I. The exaggerated response of the immune system to
certain antigens present in the environment is called
allergy.
II. The allergic tendency is genetically passed from the
parents to the offspring and is characterised by the
presence of large quantities of IgG antibodies in the
blood.
III. Bone marrow and thymus are the organs where origin
and/or maturation and proliferation of lymphocytes
occur.
IV. Immunisation is the process by which the body
produces antibodies against the vaccine preventable
diseases through administration of specific vaccines.
(a) I and II
(c) I, III and IV
(b) II and IV
(d) All of these
194 Select the correct statements.
I. The word AIDS stands for Acquired Immuno
Deficiency Syndrome. This means deficiency of
immune system, acquired during the lifetime of an
individual.
II. AIDS was first reported in 1981 and the word
‘syndrome’ in this, means a group of symptoms.
III. There is always a time-lag between the infection and
appearance of AIDS symptoms, i.e. vary from a few
months to many years (usually 5-10 years).
IV. During HIV infection, the macrophages cells of body
continues produce virus and in this way acts like a HIV
factory.
(a) I, II and III
(c) I, and IV
(b) I, III and IV
(d) All of these
195 Read the given statements carefully.
I. In India, NACO and other NGOs are doing a lot to
educate people about AIDS.
II. To prevent HIV infections, use of disposable needles
and syringes in hospitals, use of condoms during sex,
control of drug abuse is necessary.
III. Ist December is celebrated as World AIDS Day.
IV. AIDS is characterised by decrease in the number of
killer T-cells.
Which of the above statements are correct?
(a) I, II and IV
(c) I and III
(b) I, II, III and IV
(d) I and IV
196 Read the following statements and select the correct
answer.
I. Psychoactive drugs have the ability to alter the activity
of the nervous system.
II. Addiction is a psychological attachment to certain
effects such as euphoria and temporary feeling of
well-being associated with drugs and alcohol.
III. When the drugs are taken for a purpose other than
medicinal use or in amounts/frequency that impairs
one’s physical, physiological or psychological
functions, it constitutes drug abuse.
IV. Smoking increases carbon monoxide content in blood
and reduces the concentration of oxygen. This causes
oxygen deficiency in the body.
(a) I and II
(c) I, II and IV
(b) III and IV
(d) I, II, III and IV
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CHAPTER 08 > Human Health and Diseases
197 Read the following statements and select the correct
option.
I. Dependence is the tendency of the body to manifest a
characteristic and unpleasant withdrawal syndrome if
regular dose of drugs/alcohol is abruptly discontinued.
II. Excessive doses of drugs may lead to coma and death
due to respiratory failure, heart failure or cerbral
hemorrhage.
III. Education about harmful effects of drugs and alcohol,
counselling professional and medical help would
relive the individuals from the drug and alcohol abuse.
IV. Sports persons often misuse drugs to enhance their
performance.
(a) I and II
(c) I, II and III
(b) II and IV
(d) All of these
III. Matching Type Questions
Codes
A
(a) 1
(c) 2
B
2
1
C
3
3
D
4
4
A
Column II
(Causative organisms)
Dysentery
1.
Entamoeba histolytica
B. Malignant malaria
2.
Plasmodium falciparum
C. Common cold
3.
Rhinovirus
D. Ringworm
4.
Trichophyton
Codes
A
(a) 1
(c) 3
B
2
4
C
3
1
D
4
2
A
(b) 2
(d) 4
B
3
1
C
4
2
D
1
3
Column II
Haemophilus influenzae
1.
Malignant malaria
B.
Entamoeba histolytica
2.
Elephantiasis
C.
Plasmodium falciparum
3.
Pneumonia
D.
Wuchereria bancrofti
4.
Typhoid
E.
Salmonella typhi
5.
Amoebiasis
B
5
5
1
3
C
3
1
3
2
D
2
2
4
5
E
4
4
2
4
200 Match the diseases in Column I with the appropriate
Column I
Column II
A. Active natural
immunity
1.
Injection of gamma globulins
B. First line of defence
2.
Complement proteins and
interferons
C. Passive natural
immunity
3.
Direct contact with the
pathogens that have entered
inside the body
D. Second line of defence
4.
Surface barriers
5.
Antibodies transferred
through the placenta
Codes
A
(a) 4
(c) 3
B
3
4
C
5
5
D
2
2
A
(b) 3
(d) 5
B
4
3
C
2
2
D
5
1
Chemical agent
1. Benzopyrene in cigarette
smoke
B.
Physical agent
2. X-rays
C.
Biological agent
3. Oncogenic viruses
Codes
A
(a) 1
(c) 3
B
2
1
C
3
2
A
(b) 3
(d) 1
Amoebiasis
1.
Treponema pallidum
B.
Diphtheria
2.
Use only sterilised food and water
C.
Cholera
3.
DPT vaccine
D.
Syphilis
4.
Use of oral rehydration therapy
B
2
3
C
1
2
203 Match the following columns.
Column I
(Biomedical techniques)
Column II
(Features)
A.
Biopsy
1.
B.
Radiography
2.
Leukaemia
C.
Blood or Bone marrow
test
3.
X-rays are used to detect
cancer of the internal organs
D.
Computed tomography
4.
A piece of the suspected
tissue cut into thin sections,
stained and examined under
Column II
A.
Column II
(Examples)
A.
items (pathogen/prevention/treatment) in Column II.
Column I
D
3
1
Column II lists the corresponding descriptions. Match
the two column, choose the correct option from those
given.
Column I
(Cancer causing agents)
A.
Codes
A
(a) 1
(b) 3
(c) 5
(d) 1
C
1
4
202 Match the following columns.
199 Match the causative organisms with their diseases.
Column I
B
4
3
201 Column I lists the components of body defence and
198 Match the following columns.
Column I
(Diseases)
A
(b) 2
(d) 2
Uses X-rays to generate a
three- dimentional image of
the internals of an object
microscope
Codes
A
(a) 4
(c) 3
B
2
2
C
1
1
D
3
4
A
(b) 4
(d) 2
B
3
1
C
2
4
D
1
3
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210
NCERT & NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
NCERT
211 Diseases are broadly grouped into infectious and
204 Which one of the following diseases causes dry, scaly
lesions on skin, nails and scalp?
(a) Ringworm disease
(c) Botulism
(b) Skin allergy
(d) None of these
205 Which one of the following pairs of diseases are viral
as well as transmitted by mosquitoes?
(a)
(b)
(c)
(d)
(d) II and IV
(b) ESR test
(d) Widal test
213 Many diseases can be diagnosed by observing the
use of highly effective vaccine
immunisation programmes
elimination of animal reservoir
international cooperation
NCERT Exemplar
207 The term ‘Health’ is defined in many ways. The most
accurate definition of the health would be
(a) health is the state of body and mind in a balanced
condition
(b) health is the reflection of a smiling face
(c) health is a state of complete physical, mental and social
well-being
(d) health is the symbol of economic prosperity
208 Transplantation of tissues/organs fails often due to the
non-acceptance by the patient’s body. Which type of
immune-response is responsible for such rejections?
NEET 2018
Autoimmune response
Cell-mediated immune response
Hormonal immune response
Physiological immune response
209 When an apparently healthy person is diagnosed as
unhealthy by a psychiatrist, the reason could be that
(a) the patient was not efficient at his work
(b) the patient was not economically prosperous
(c) the patient shows behavioural and social
maladjustment
(d) he does not take interest in sports
210 The organisms which cause diseases in plants and
symptoms in the patient. Which group of symptoms
are indicative of pneumonia?
(a) Difficulty in respiration, fever, chills, cough and
headache
(b) Constipation, abdominal pain, cramps and blood clots
(c) Nasal congestion and discharge, cough, sore throat and
headache
(d) High fever, weakness, stomach pain, loss of appetite
and constipation
214 The disease chikungunya is transmitted by
(a) house flies
(c) cockroach
(b) Aedes mosquitoes
(d) female Anopheles
215 The sporozoites that cause infection when a female
Anopheles mosquito bites a person, are found in
(a) liver of the person
(b) RBCs of mosquito
(c) salivary glands of mosquito
(d) gut of masquito
216 A person with sickle-cell anaemia is
(a) more prone to malaria (b) more prone to typhoid
(c) less prone to malaria (d) less prone to typhoid
217 Haemozoin is a
(a) precursor of haemoglobin
(b) toxin released from Streptococcus infected cells
(c) toxin released from Plasmodium infected cells
(d) toxin released from Haemophilus infected cells
218 Which of the following is not the causal organism for
ringworm?
(a) Microsporum
(c) Epidermophyton
(b) Trichophyton
(d) Macrosporum
219 The substance produced by a cell in viral infection
that can protect other cells from further infection is
animals are called
(a) pathogens
(c) insects
(b) II and III (c) III and IV
(a) ELISA test
(c) PCR test
following facts except
(a)
(b)
(c)
(d)
Codes
(a) I and II
212 The clinical test that is used for diagnosis of typhoid is
Elephantiasis and dengue
Malaria and yellow fever
Ringworm and dengue
Yellow fever and dengue
206 Eradication of smallpox has been possible due to the
(a)
(b)
(c)
(d)
non-infectious diseases. In the list given below,
identify the infectious diseases.
I. Cancer
II. Influenza
III. Allergy
IV. Smallpox
(b) vectors
(d) worms
(a) serotonin
(c) interferon
(b) colostrum
(d) histamine
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211
CHAPTER 08 > Human Health and Diseases
225 AIDS is caused by HIV. Among the following, which
220 Antibodies present in colostrum which protect the
newborn from certain diseases is of
one is not a mode of transmission of HIV?
(a) IgG type
(c) IgD type
(a) Transfusion of contaminated blood
(b) Sharing the infected needles
(c) Shaking hands with infected persons
(d) Sexual contact with infected persons
(b) IgA type
(d) IgE type
221 Antivenom against snake poison contains
(a) antigens
(c) antibodies
(b) antigen-antibody complexes
(d) enzymes
226 The genes causing cancer are
(a) structural genes
(b) expressor genes
(c) oncogenes
(d) regulatory genes
222 Which of the following are the reasons for
rheumatoid arthritis?
I. The ability to differentiate pathogens or foreign
molecules from self cells increases.
II. Body attacks self cells.
III. More antibodies are produced in the body.
IV. The ability to differentiate pathogens or foreign
molecules from self cells is lost.
Choose the correct option.
(a) I and II
(c) III and IV
227 In malignant tumours, the cells proliferate, grow
rapidly and move to other parts of the body to form
new tumours. This stage of disease is called
(a) metagenesis
(c) teratogenesis
228 ‘Smack’ is a drug obtained from the
(b) II and IV
(d) I and III
(a) latex of Papaver somniferum
(b) leaves of Cannabis sativa
(c) flowers of Datura pinata
(d) fruits of Erythroxylum coca
223 Which of the following is not a secondary lymphoid
tissue?
(a) Spleen
(b) Tonsils
(c) Appendix
(d) Thymus
(b) metastasis
(d) mitosis
229 Tobacco consumption is known to stimulate secretion
224 Which of the following glands is large sized at birth
but reduces in size with ageing?
of adrenaline and nor-adrenaline. The component
causing this could be
(a) Pineal
(c) Thymus
(a) nicotine
(c) curcumin
(b) Pituitary
(d) Thyroid
(b) tannic acid
(d) catechin
Answers
‡ Mastering NCERT with MCQs
1 (d)
16 (a)
31 (d)
46 (a)
61 (d)
76 (b)
91 (d)
106 (b)
121 (a)
136 (d)
151 (a)
2 (b)
17 (d)
32 (d)
47 (b)
62 (d)
77 (d)
92 (a)
107 (a)
122 (a)
137 (a)
152 (b)
3 (b)
18 (c)
33 (c)
48 (c)
63 (a)
78 (c)
93 (b)
108 (b)
123 (a)
138 (a)
153 (d)
4 (a)
19 (b)
34 (c)
49 (d)
64 (d)
79 (a)
94 (a)
109 (d)
124 (a)
139 (d)
154 (a)
5 (d)
20 (d)
35 (a)
50 (d)
65 (a)
80 (b)
95 (a)
110 (a)
125 (d)
140 (b)
155 (c)
6 (b)
21 (a)
36 (a)
51 (d)
66 (d)
81 (a)
96 (a)
111 (c)
126 (a)
141 (a)
156 (c)
7 (a)
22 (d)
37 (a)
52 (c)
67 (a)
82 (c)
97 (b)
112 (c)
127 (d)
142 (c)
157 (a)
8 (c)
23 (c)
38 (b)
53 (d)
68 (c)
83 (b)
98 (d)
113 (a)
128 (d)
143 (c)
158 (c)
9 (a)
24 (c)
39 (c)
54 (c)
69 (a)
84 (c)
99 (a)
114 (a)
129 (b)
144 (d)
159 (b)
10 (d)
25 (b)
40 (c)
55 (a)
70 (a)
85 (a)
100 (a)
115 (a)
130 (d)
145 (b)
160 (a)
11 (a)
26 (d)
41 (c)
56 (d)
71 (c)
86 (a)
101 (a)
116 (b)
131 (c)
146 (c)
161 (c)
12 (b)
27 (b)
42 (c)
57 (d)
72 (a)
87 (c)
102 (a)
117 (d)
132 (c)
147 (a)
162 (d)
13 (c)
28 (d)
43 (b)
58 (c)
73 (a)
88 (d)
103 (a)
118 (b)
133 (a)
148 (a)
14 (d)
29 (b)
44 (d)
59 (a)
74 (c)
89 (a)
104 (a)
119 (c)
134 (a)
149 (d)
15 (a)
30 (a)
45 (a)
60 (b)
75 (d)
90 (a)
105 (a)
120 (d)
135 (b)
150 (a)
‡ NEET Special Types Questions
163 (b) 164 (a) 165 (d) 166 (a) 167 (a) 168 (a) 169 (a) 170 (a) 171 (b) 172 (a) 173 (b) 174 (a) 175 (d) 176 (b) 177 (c)
178 (c) 179 (a) 180 (b) 181 (a) 182 (c) 183 (a) 184 (c) 185 (c) 186 (d) 187 (d) 188 (c) 189 (d) 190 (d) 191 (d) 192 (a)
193 (c) 194 (d) 195 (b) 196 (d) 197 (d) 198 (a) 199 (b) 200 (d) 201 (c) 202 (a) 203 (b)
‡ NCERT & NCERT Exemplar Questions
204 (a) 205 (d) 206 (c)
207 (c)
219 (c)
222 (b) 223 (d) 224 (c)
220 (b) 221 (c)
208 (b) 209 (c)
210 (a) 211 (d) 212 (d) 213 (a) 214 (b) 215 (c)
225 (c)
226 (c)
216 (c)
217 (c)
218 (d)
227 (b) 228 (a) 229 (a)
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212
Answers & Explanations
6 (b) A disease, which can be easily transmitted from one
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Answers & Explanations
18
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21
22
person to another is called infectious disease. Infectious
diseases are also known as transmissible disease or
communicable disease.
(c) Typhoid fever is caused by the bacterium
Salmonella typhi and widal test is the confirmatory test
for typhoid, which is based on antigen-antibody
interaction. Typhoid fever or Enteric fever has the
incubation period of 1 to 2 weeks.
(a) Mary Mallon (nick named Typhoid Mary, born on
September 23, 1869, Cookstown, Country Tyrone,
Ireland). She was a cook by profession and was a
famous typhoid carrier who allegedly gave rise to
multiple outbreaks of typhoid fever through the food
she prepared.
(b) The correct option is (b) as
Bacteria like Streptococcus pneumoniae and
Haemophilus influenzae are responsible for the disease
pneumonia in humans, which infects the alveoli (air
sacs) of the lungs.
(a) Cholera and tetanus are diseases caused by bacteria.
Cholera is caused by a bacterium Vibrio cholerae and
tetanus is caused by a bacterium Clostridium tetani.
Mumps, influenza, herpes and smallpox are viral
diseases. Typhoid is a bacterial disease but, it is not
paired with a bacterial disease.
Hence, option (a) is correct.
(a) Rhinoviruses represent one such group of viruses,
which cause one of the most infectious human
ailments– the common cold.
(d) Pneumonia is caused by the bacteria Streptococcus
pneumoniae and Haemophilus influenzae which infect
the alveoli of lungs.
On the other hand, common cold is caused by a variety
of viruses, most commonly by rhinovirus (RNA virus)
and affects the upper respiratory tract, but not the lungs.
(c) HIV, hepatitis-B and ebola virus spread through
direct contact between individuals. Direct transmission
of vectors or disease occurs through sexual contact,
exchange of body fluids like blood, semen, etc.
Chikungunya is caused by the bite of Aedes aegypti
mosquito, which requires no direct contact with body
fluids like blood, semen or saliva for its transmission.
(d) Different species of Plasmodium (P. vivax,
P. malariae, P. falciparum and P. ovale) are responsible
for causing different types of malaria.
(a) Malignant malaria is caused by Plasmodium
falciparum, which is the most serious type of malaria as
it can even be fatal.
(d) When an infected female Anopheles bites a healthy
person, Plasmodium in the form of ‘sporozoites’ are
transmitted from saliva of mosquito into the human
body. Thus, one can look for the sporozoites of the
malarial parasite in the saliva of the infected female
Anopheles mosquito.
23 (c) Infective stage of Plasmodium for man is sporozoite.
24
26
30
32
33
Plasmodium enters the human body as sporozoites
(infectious form) through the bite of infected female
Anopheles mosquito.
The sporozoites mature into schizonts in the liver cells
and releases merozoites upon rupture. These merozoites
infect RBCs. Ookinete is the motile zygote of the
parasite of the malarial mosquito that forms an oocyst in
the mosquito’s gut.
(c) Haemozoin is the toxic substance which is
responsible for the high malarial fever. It is released due
to the rupture of RBCs in the liver of human by the
malarial parasite.
(d) Female Anopheles is the primary host of the malarial
parasite (Plasmodium). It is called primary host, as it
serves as the place where Plasmodium lives and
reproduces sexually. Human is called the secondary
host of Plasmodium.
(a) Entamoeba histolytica causes amoebiasis. It is a
parasite of the large intestine of humans and is commonly
contracted by ingesting contaminated water or food.
(d) Malaria, amoebiasis and sleeping sickness all are
protozoan diseases caused by the species of the
protozoan Plasmodium, Amoeba and Trypanosoma,
respectively.
(c) Babesiosis is a malaria-like parasitic disease caused
by infection with Babesia bigemina, a genus of
protozoan piroplasms.
The diseases in the other options and their causative
agents are as follows
Syphilis
—
Influenza
—
Blastomycosis —
Treponema pallidum (bacterium)
Influenza virus
Blastomyces dermatitidis (fungus)
34 (c) Trichinella spiralis, a nematode parasite copulates in
the intestine, after which males dies and females
produce larvae which enter into the blood circulation to
reach the muscles. The production of larvae indicates
vivipary.
Ancylostoma, Enterobius and Ascaris are all egg laying
endoparasites.
35 (a) Ascariasis is caused by an intestinal endoparasite of
human, ‘Ascaris lumbricoides,’ commonly called
roundworm.
Filariasis is caused by filarial worms, Wuchereria
bancrofti and Wuchereria malayi.
Both of these causative agents are helminths.
36 (a) Symptoms of ascariasis includes internal bleeding,
muscular pain, fever, anaemia and blockage of the
intestinal passage. Ascariasis is caused by an
endoparasite of human, Ascaris lumbricoides
commonly called roundworm.
37 (a) Infection of Ascaris occurs in a healthy person due
to the drinking of water contaminated with eggs of
Ascaris, vegetables (raw or uncooked), fruits, etc.
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40 (c) The filariasis pathogens are transmitted to a healthy
59 (a) Interferon is a suitable example of cytokine barrier.
person through the bite of female of the pathogen
mosquito Culex vectors. Which also serves as
intermediate host.
42 (c) Elephantiasis is a helminthic disease caused by
Wuchereria bancrofti and W. malayi. The infestation is
transmitted by female Culex mosquitoes from one
individual to the others. The worms live in the
lymphatic system and slowly develops chronic
inflammation.
For the other options
These are the proteins secreted by virus-infected cells and
protect non-infected cells from further viral infection.
(d) Interferon (a kind of protein) is a polypeptide
produced by a T-cell infected with a virus that diffuses
to surrounding cells and stimulates them to manufacture
biochemicals that hinder viral replication. Thus,
interferons can be used to encounter diseases caused by
virus, i.e. hepatitis and common cold.
(d) Interferons block viral reproduction in healthy cells
and measles is caused by the measles virus.Thus, a
person will develop interferons in his body, for the
infection of measles.
(a) Option (a) represents the cells involved in second
line of defence. The second line of non-specific defence
is primarily dependent upon neutrophils and
macrophages, phagocytic white cells (phagocytes) in
blood and lymph. Second line of defence also includes
the functioning of interferons and the proteins of the
complement system.
(d) Option (a) and (b) both are correct as
Antibodies are proteins produced in our body in
response to antigens (pathogens).
Antibody molecule specifically interacts with an antigen
to produce an immune response. These are secreted by
the action of both B-lymphocytes and T-lymphocytes.
(c) IgG is the most abundant class of immunoglobulins
in the human body. IgA, IgM, IgE, IgG, etc., are some
of the different types of structurally related proteins
(immunoglobulins) that act as antibodies.
(a) Humoral immunity is also called as antibody
mediated immunity. It refers to immunity provided by
substances in the body fluid. Since, antibodies are found
in the blood, therefore antibody mediated immunity is
also referred to as humoral immunity.
(a) Humoral immunity consists of antibodies in the
blood and lymph. B-lymphocytes secrete antibodies.
Thus, humoral immunity is mediated by B-cells or
B-lymphocytes.
(a) The cell-mediated immunity is one of the type of
acquired immunity of human body which is carried out
by the T-lymphocytes.
(c) Cell-mediated immune response is responsible for
the rejection of kidney graft. It is conferred by
sensitised T-lymphocytes and here, antibodies are not
produced.
T-cells confer a long term memory and are able to
discriminate between self and non-self. These cells
sometimes consider graft as non-self and attack it,
which causes its rejection.
(d) Active immunity is an immunity, which is gained
after natural infection and on exposure to live
pathogens. In this type of immunity, the body produces
antibodies as a response to specific pathogens or
antigens.
(b) Active immunity development is related to memory
cells formed when B-cells and T-cells are activated by a
l
l
l
Ringworm is a fungal skin disease.
Ascariasis pathogen affects small intestine of human
beings.
Amoebiasis pathogen affects the large intestine of
humans.
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62
63
43 (b) Pair in option (b) is not correctly matched and can
be corrected as
Syphilis is caused by bacteria Trypanosoma pallidum.
Rest of the other pairs show correct match.
44 (d) The group of diseases carried (transmitted) by
insects are
64
Malaria transmitted by by Anopheles mosquito (female).
Filariasis transmitted by by Culex (female).
Yellow fever transmitted by Aedes (female).
46 (a) Fungi parasitic on the skin, usually belong to the
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49
51
56
57
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genera of Microsporum, Epidermophyton or
Trichophyton. Such fungi are responsible for ringworm
infection and are also called cutaneous fungus.
(b) Ringworm is an infectious disease. It is a skin
infection caused by a fungus that can affect the scalp,
skin, fingers, toes, nails or foot.
(d) Gambusia is a fish which can control mosquito
borne diseases like dengue, chikungunya, malaria, etc.
These fishes feeds on larvae and pupae of certain
mosquitoes and help in eradication of various insect
borne diseases.
(d) Innate immunity is also known as
inborn/familiar/natural or genetic immunity. Innate
immunity is the non-specific type of defence that is
present in an individual at the time of birth.
(d) The major phagocytic cells are macrophages. These
cells perform phagocytosis, i.e. the process of engulfing
a solid particle by a phagocyte.
(d) Option (d) is correct as
Cellular barrier of the body includes certain types of
leucocytes (WBC) of the body like Poly
Morpho-Nuclear Leucocytes (PMNL-neutrophils) .
Monocytes and natural killer (type of lymphocytes) in
the blood as well as macrophages in tissues which can
phagocytose and destroy microbes.
(c) Innate immunity is the non-specific type of defence
that is present at the time of birth because it has natural
killer cells which can phagocytose and destroy microbes
(cellular barriers). Other forms of innate immunity are
physical, physiological and cytokine barriers.
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pathogen. These cells recognise the pathogen quickly on
subsequent exposure and overwhelm the invaders with a
massive production of antibodies.
(d) Passive immunity results when antibodies are
directly given to an individual to protect the body
against foreign agents. The acquisition of the antibodies
in colostrum by an infant and the crossing of the
placenta by maternal antibodies are examples of
naturally acquird passive immunity.
(c) Colostrum, the yellowish fluid, secreted by mother
during the initial days of lactation is very essential to
impart immunity to the newborn infants because it
contains immunoglobulin-A. As IgA is secreted in
mother’s milk, it is also called secretory
immunoglobulin.
(a) IgA antibody is involved in passive immunity. In
this type of immunity, antibodies are directly given to
protect the body against foreign agents. It is short lived.
(b) Option (b) represents the correct information
regarding antibodies. IgG antibody can cross placenta
and provide natural passive immunity to the developing
foetus. Other options are incorrect and can be corrected
as follows
l
l
l
IgA is a dimer found in body secretions such as sweat,
tears, saliva, mucus, colostrum , etc. It provides
localised protections from pathogens.
IgE is involved in hypersensitive reactions and presents
in mast cells and basophill cells.
IgM is found in pentamer form not as dimer.
81 (a) The principle of vaccination or immunisation is
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Answers & Explanations
83
84
85
86
based on the property of memory of the immune
system. The memory cells recognise the pathogen
quickly and control the invaders by producing a large
number of antibodies.
(c) The pathogens used in vaccines are weakened and
inactivated pathogenic agents. This stimulates the body to
produce enough antibodies to protect against the disease.
(b) Passive immunity refers to when antibodies are
directly injected into the body to generate immune
response. Thus, if a person is infected with some deadly
microbes to which quick immune response is required
as in tetanus, we directly inject the preformed
antibodies or antitoxin into the body of the infected
person. This is passive immunisation.
(c) Oral polio vaccine consists of attenuated pathogens.
Attenuated pathogens are living microorganisms or
viruses cultured under adverse condition which leads to
the loss of their virulance.
But these organisms have the ability to induce lifelong
immunity. The oral vaccine of polio contains three live
polio strains in attenuated forms.
(a) Human hepatitis-B virus vaccine was prepared by
using antigen produced by recombinant strain of the
yeast, Saccharomyces cerevisiae.
(a) An allergen is any substance (antigen), most often
eaten or inhaled, that is recognised by the immune
system and causes an allergic reaction.
87 (c) IgE is an antibody which mediates allergic reactions.
It plays a pivotal role in response to allergens such as
anaphylactic drugs, bee stings, etc. They are synthesised
by plasma cells and are found in only mammals.
88 (d) Allergens such as pollen grains, animal dander, dust,
feathers, drugs like penicillin, etc., are non-infectious
foreign substances, which induce allergic reaction in the
body.
90 (a) For determining the cause of allergy, the patient is
exposed to or injected with very small doses of possible
allergens and the reactions displayed or observed.
92 (a) Asthma may be attributed to allergic reaction of the
mast cells in the lungs. It is an allergic reaction
characterised by spasm of bronchi muscles because of
the effect of histamine released by mast cells in the
lungs.
93 (b) In autoimmune disorder, the immune cells are
unable to distinguish between self-cells and non-self
cells and attack the self-cells. This occurs due to some
genetic abnormality, e.g. rheumatoid arthritis.
94 (a) Myasthenia gravis is a chronic autoimmune
neuromuscular disorder that causes fatigue, weakening
and paralysis of skeletal muscles. In this, neuromuscular
junctions are affected as the body produces antibodies
which block the muscle from receiving signal from the
nerve cells.
95 (a) Alzheimer’s disease is not an automimmune disease.
It is caused due to the destruction of a large number of
neurons in the hippocampus. It occurs due to a
combination of genetic factors, environmental or
lifestyle factors and the ageing process.
In this, there is loss of neurotransmitter acetylcholine.
Individuals with this disease have trouble remembering
recent events.
Rest all are autoimmune diseases.
97 (b) The primary lymphoid organs are bone marrow and
thymus.
The secondary lymphoid organs are spleen, lymph nodes,
tonsils, Peyer’s patches of small intestine and appendix.
98 (d) Thymus provides the micro-environment for the
development and maturation of T-lymphocytes. Thus,
surgical removal of thymus of a newborn shall result in
failure to produce T- lymphocytes.
99 (a) The thymus is a lobed gland located near the heart
and beneath the breast bone, consisting mainly of
lymphatic tissues and serving as the site of T-cell
differentiation.
103 (a) MALT is Mucosal Associated Lymphoid Tissue
located within the lining of the major tracts like
respiratory, digestive and urinogenital tracts. It
constitutes nearly 50% of the total lymphoid tissue in
the human body.
105 (a) Human Immunodeficiency Virus (HIV) is a
retrovirus (slowly replicating) that causes Acquired
Immuno Deficiency Syndrome (AIDS).
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person infected by AIDS. This can be explained as after
entering the body of a healthy person, the HIV enters
into macrophages where RNA genome of the virus
replicates to form viral DNA with the help of the
enzyme reverse transcriptase.
(c) When HIV damages a large number of helper
T-lymphocytes, the infected person starts showing
symptoms of AIDS like bouts of fever, diarrhoea and
weight loss.
(b) In our body, cell growth and differentiation is highly
controlled and regulated. But abnormal mitosis in an
organ results in cancer.
(c) The properties possessed by malignant tumour are
uncontrolled cell division and metastasis, i.e. they do
not remain confined in the area of formation and reach
distant sites through blood, and wherever they get
lodged in the body, these start the formation of a new
tumour there.
(d) Option (d) is not a property of cancerous cells.
Contact inhibition involves major histocompatibility
complex and is the natural process of arresting cell
growth when two or more cells come in contact with
each other. It is a property of normal cells. Cancer cells
divide in uncontrolled manner and do not show contact
inhibition.
Remaining three are the properties of cancerous cells.
(a) Transformation of normal cell into cancerous
neoplastic cells is induced by carcinogens. These
carcinogens can be physical, chemical or biological
agents.
(a) Physical carcinogens include a wide range of agents,
e.g. ionising radiations like X-rays and γ-rays and
non-ionising radiations like UV rays. These cause DNA
damage leading to neoplastic transformation.
(a) Tumour virus or cancer causing viruses are called
oncogenic viruses. These viruses have oncogenes. An
oncogene is a gene that has the potential to cause
cancer. In tumour cells, these are often mutated or
expressed at high levels.
(d) Cancer cells show metastasis. Cancerous cells are
actively dividing cells which starve the normal cells by
competing for vital nutrients. These cancerous cells
reach distant sites through blood and get lodged in the
body and start a new tumours (masses of cells). This
property of cancer cells is called metastasis.
(b) Cancer is caused by loss of control over cell's
reproductive capacity. They undergo rapid division and
therefore, they are more easily damaged by radiations
than normal cells.
(c) Tumour cells have been shown to avoid detection
and destruction by immune system. Therefore, the
patients are given substances called biological response
modifiers such as α-interferon, which activates their
immune system and helps in destroying the tumours.
134 (a) The drug ‘heroin’ is synthesised by the acetylation
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of morphine. Chemically heroin is diacetylmorphine and
commonly it is called smack. It is an opium derivative
which is used as a medicine. However, its excessive use
causes addiction.
(b) The latex of poppy plant (Papaver somniferum) is
used to obtain ‘smack’. It is a white, crystalline,
odourless, bitter compound, which acts as a depressant
and slows down the body functions.
(a) Natural cannabinoids are obtained from the leaves,
resin and inflorescence of Cannabis sativa.
(b) Cannabinoids such as ganja, charas, merijuana and
hashish are effect cardiovascular system of the body.
(a) Option (a) is correct.
Fig A represents morphine a potent opiate analgesic
drug that is used as sedative and to relieve severe pain.
It is given to patients who have undergone surgery. It is
taken by snorting and injection.
The other options can be corrected as
Fig B represents cannabinoids are known for its effect
on cardiovascular system of the body. These are taken
by inhalation and oral ingestion.
(c) Coca alkaloid or cocaine is obtained from the coca
plant Erythroxylum coca, native to South America. It is
a natural stimulant and interferes with the transport of
the neurotransmitter dopamine.
(c) Cocaine, is commonly called coke or crack. It is
usually snorted. Excessive dosage of cocaine causes
hallucinations.
(d) Traditionally, Erythroxylum (cocaine) was used to
obtain anesthesia. It has an anesthetic and analgesic
property which can alleviate the pain of headache,
rheumatism, wounds and sores, etc. It was also used for
broken bones, childbirth and during performing
trepanning operations on the skull.
(b) Cocaine is a potent stimulant drug as it directly
affects the central nervous system by producing a sense
of euphoria and increased energy.
(a) The plant shown in the given picture is Datura, which
produces natural hallucinogens. These drugs induce
behavioural abnormalities by changing thoughts, feelings
and perceptions without any actual sensory stimulus.
(d) Drugs like barbiturates, amphetamines,
benzodiazepines, Lysergic Acid Diethylamide (LSD)
and other similar drugs, are normally used as medicines
to help patients cope with mental illnesses like
depression and insomnia.
150 (a) Lysergic Acid Diethylamide (LSD) is an extremely
potent psychedelic ergot alkaloid derived from the
fungus, Claviceps purpurea. LSD is one of the most
powerful hallucinogenic drugs known. It was invented
in 1938 by the Swiss chemist, Albert Hoffman, who
was interested in developing medicines from
compounds in ergot, a fungus that attacks rye.
Answers & Explanations
111 (c) Macrophages are known as ‘HIV’ factory in a
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Master The NCERT > BIOLOGY (Vol-II)
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151 (a) Option (a) shows the correctly matched pair of drug
with its category.
Others matching pairs are incorrect and can be corrected as
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Lysergic acid diethylamide–Psychedelic drug.
Heroin–Analgesic
Benzodiazepines–Psychotropic drug.
152 (b) Amanita muscaria, is a fungus which is known for
containing hallucinogenic (profound misinterpretation in a
person’s perceptions of realty) properties.
153 (d) Nicotine is both an alkaloid and a steroid and it is
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Answers & Explanations
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extracted from the leaves of tobacco plant. An alkaloid is
a nitrogenous organic compound of plant origin which has
physiological actions on humans and steroids are synthetic
drugs that closely resemble, cortisol, a hormone of adrenal
gland.
(c) Smoking addiction is harmful because smoke produces
polycyclic aromatic hydrocarbons, currently classified as
human carcinogens as these cause cancer.
(c) Emphysema is a type of Chronic Obstructive
Pulmonary Disease (COPD) involving damage to the air
sacs (alveoli) in the lungs.
(a) Benzopyrene is the carcinogen present in cigarette
smoke. It is a polycyclic aromatic hydrocarbon formed as
a result of incomplete combustion of organic matter such
as coal, tar, tobacco, etc. It is a potential carcinogenic
compound listed as Group 1 carcinogen by the IARC or
International Agency for Research on Cancer. It reacts
and binds to DNA, resulting in mutation and eventually
leads to cancer.
(c) Those who take drugs intravenously (direct injection
into the vein using a needle and syringe), are much more
likely to acquire serious infections like AIDS and
hepatitis-B.
This is because the viruses, which are responsible for these
diseases, are transferred from one person to another by
sharing of infected needles and syringes.
(b) Cirrhosis of liver is caused by chronic intake of
alcohol, which may be fatal for an individual. On intake, a
part of alcohol is changed to acetaldehyde which causes
hangover. Acetaldehyde stimulates formation of fat which
is deposited on artery walls (causing coronary ailments)
and in the liver (causing fatty liver syndrome). Gradually,
the liver hardens and dries up as its cells are replaced by
fibrous tissue. This kind of liver degeneration is called
liver cirrhosis (Laennec’s cirrhosis). Excessive use of
alcohol may also lead to liver failure, liver cell carcinoma,
etc.
(c) Cerebrum is involved in the loss of control over
speech when a person consumes excessive alcohol. It
attacks Broca’s area which is related to speech
production. When a person consumes alcohol, it interfers
with the brain’s communication pathways and thus,
affects the brain’s information processing system and
speech.
(d) Option (d) is correct. The side effects of the use of
anabolic steroids in females include masculinisation
(features like males), increased aggressiveness, mood
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swings, depression, abnormal menstrual cycles,
excessive hair growth on the face and body,
enlargement of clitoris, deepening of voice.
In males, the side effects include acne, increased
aggressiveness, mood swings, depression and
reduction of size of the testicles, decreased sperm
production, potential for kidney and liver dysfunction,
breast enlargement, premature baldness, enlargement
of the prostate gland. These effects may be permanent
with prolonged use.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Shigella sp., Salmonella sp. and Escherichia coli are
quite closely related genera of pathogenic bacteria
that are responsible for diarrhoeal diseases.
Dehydration is common symptom to all types of
diarrhoeal diseases and adequate supply of fluids and
electrolytes that provide ions, should be ensured.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Virus infected cells secrete proteins called interferons,
which protect non-infected cells from further viral
infection.
(d) Assertion is false, but Reason is true. Assertion
can be corrected as
Interferon is a glycoprotein, production of which is
induced within viral infected cells. Interferon induces
an antiviral state within adjacent cells by interfering
with viral replication.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Antibody mediated immune response occurs due to
antibodies produced in the blood. These antibodies
are chiefly secreted by B-cells into the body fluids.
When an antigen (pathogen) enters the body the
B-cells produce antibodies (immunoglobulins) in
response to it.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Tetanus is bacterial disease which is caused by an
exotoxin produced by Clostridium tetani. The wound
anoxic conditions allows the germination of
endospores and growth of the microorganism. So, a
person with a bleeding wound needs anti-tetanus
treatment. Anti-tetanus injection or antitoxin is a
preparation of modified bacterical toxin that has been
made non-toxic, but retains the capacity to stimulate
the formation of antitoxins. It is usaually made in
horses.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
The exaggerated response of the immune system to
certain antigens present in the environment is called
allergy. The substances to which such an immune
response is produced are called allergens (antigens).
Allergens in the environment on reaching human
body stimulate mast cells, which release excessive
amount of chemicals like histamine. These chemicals
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CHAPTER 08 > Human Health and Diseases
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with alcohol. Thus, athletes undergo dope test major
tournaments or a match.
176 (b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Repeated use of drugs, increase the tolerance level of
receptors in our body because consumption or use of
drugs for a longer period of time increases the number
of receptors at neural junction which inturn, increases
the tolerance level. Consequently, receptors respond
only to higher doses of drugs thereby causing addiction.
177 (c) Assertion is true, but Reason is false. Reason can be
corrected as
Pork does not contain hexacanth larva as it gets
converted into cysticercus form in the voluntary
muscles of the pig.
Humans get Taenia infection through direct or oral
means. It occurs by eating raw or undercooked measly
pork (pig muscle with cysticercus larvae of Taenia).
Infection in vegetarians occurs through improperly
washed vegetables. So, proper cooking of pork and
properly washed vegetables can help to avoid Taenia
infection.
179 (a) The statement in option (a) is correct with respect to
immunity.
Rest of the statements are incorrect and can be corrected
as
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The antibodies against smallpox pathogen are produced
by memory cell is B-lymphocytes.
Antibody is a protein molecule having two light chains
and two heavy chains.
Rejection of kidney graft is the function of
T-lymphocytes.
180 (b) The statement in option (b) is correct. Rest of the
statements are incorrect and can be corrected as
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HIV is an enveloped retrovirus.
HIV escapes the immune cells and attacks helper T-cells
of immune system.
182 (c) Statements I, III and V are correct. Statements II and
IV are incorrect and can be corrected as
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Acquired immunity is not present from the birth and
develops during an individual’s lifetime. It is pathogen
specific. Thus, it is called specific immunity.
Innate immunity is non-specific immunity.
183 (a) Statements I, II and III are correct, but statement IV
is incorrect and can be corrected as
l
Dengue and chikungunya both are spread by Aedes
mosquitoes.
193 (c) Statements I, III and IV are correct, but statement II
is incorrect. It can be corrected as
Allergic tendency can be genetically passed from the
parents to their offspring and is characterised by the
presence of large quantities of IgE antibodies in the
blood.
204 (a) Ringworm disease causes symptoms like dry, scaly
and lesions on skin, nails and scalp. These lesions also
are also accompanied by intense itching.
Answers & Explanations
169
cause marked dilation of all the peripheral blood vessels
and the capillaries become highly permeable, so that
large amounts of fluid leak out from the blood into the
tissues thereby causing allergy.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Gymnosperms like Pinus usually grow on the slopes of
hills and form dense forests of evergreen trees. The
pollination of these plants takes place through wind and
during peak hours, the microspore of Pinus are liberated
as clouds of yellow dust (sulphur shower). On
inhalation, these microspores (pollens) cause various
allergies like dermatitis, asthma, allergic rhinitis, hay
fever, etc., in human beings.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
HIV or Human Immunodeficiency Virus is the
causative agent of AIDS. AIDS arises due to the
deficiency of the immune system acquired during the
life time of a host. HIV causes AIDS by damaging the
immune system of the human body.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Cancer is caused by damage to genes regulation of the
cell division cycle. It is an uncontrolled proliferation of
the cells. These cancerous cells become immortal
because of the breakdown of the cell growth and
differentiation regulatory mechanisms and the loss of a
property called contact inhibition.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Metastasis is the phenomenon in which tumour cells
detach and migrate to other parts of the body where they
give rise to secondary tumours (i.e. masses of cells
produced at different locations in the body). Metastasis
is the property of cancerous cells, which have abnormal
antigens on their surface and unusual number of
chromosome in their nucleus thereby causing
metastasis.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Cannabinoids are chemicals known for their effects on
cardiovascular system of the body, as these increase the
heart rate, blood pressure, etc. Cannabinoids interact
with cannabinoid receptors present in the brain and
cause hallucinogenic effects.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
High alcohol consumption is harmful during pregnancy.
This is because Foetal Alcohol Syndrome (FAS) is the
name given to a group of physical and mental defects
caused by foetal exposure to alcohol in the womb.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Dope test is the blood test used to estimate whether a
person taking part in a competition used any drug to
make their performance better. Dope test is not related
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Master The NCERT > BIOLOGY (Vol-II)
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206 (c) Option (c) is incorrect and can be corrected as
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Animal reservoir of the smallpox does not exist.
Rest all options contain facts which led to smallpox
eradication.
(b) Transplantation of tissue/organs may fail, when that
tissue is rejected by the recipient’s immune system leading
to its destruction. Tissue rejection is a function of
cell-mediated immune response that involves T-cells.These
cells have the ability to distinguish between self and nonself cells. After the recognition of non-self tissue the killer
T-cells induces apoptosis of the target tissue.
(c) Health can be defined as a state of complete physical,
mental and social well-being. So, when an apparently
healthy person is diagnosed as unhealthy by a psychiatrist,
the reason could be that the patient shows behavioural and
social maladjustment due to the mental discomfort.
(a) A wide range of organisms including bacteria, viruses,
fungi, protozoans, helminths, etc., cause diseases in plants
and animals. Such disease causing organisms are called
pathogens. On the other hand, vectors are the carriers of
pathogens which may be insects or worms.
(d) Influenza (commonly known as the ‘flu’) and smallpox
are infectious diseases.These diseases can get transmitted
from an unhealthy person to a healthy person by physical
means diseases.
Whereas, cancer and allergy are non-infectious and
non-transferable disease.
(a) Option (a) represents the group of symptoms which are
indicative of pneumonia. Rest of the symptoms and their
respective diseases are given below
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Constipation, abdominal pain, cramps and blood clots
indicate amoebiasis.
Nasal congestion and discharge, cough, sore throat and
headache indicate common cold influenza.
High fever, weakness, stomach pain, loss of appetite and
constipation indicate typhoid.
Answers & Explanations
215 (c) Sporozoites enter the female Anopheles mosquito when
they bite an infected person where these sporozoites
fertilise and multiply in the stomach wall of the female
Anopheles. These then get stored in the salivary glands of
the mosquito till it is again transferred to the human body
by a mosquito bite.
216 (c) People suffering from sickle-cell anaemia are less
prone to malarial parasite as RBC of sickle-cell anaemic
patients is distorted in shape. The membrane of the
sickle-cells are stretched due to their distorted shape and
thus, become porous. The cells leak all the nutrients
needed by the parasite to survive and the faulty cells along
with the parasite eventually get eliminated.
217 (c) Haemozoin is a toxin released by Plasmodium infected
cells. This substance is responsible for producing chills
and high fever recurring every three to four days.
218 (d) Ringworm infections are caused by fungi belonging to
the genera–Microsporum, Trichophyton and
Epidermophyton.
Macrosporum is not a causal organism for ringworm.
219 (c) The cytokine-barriers include interferons. These
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are the proteins secreted by virus infected cells,
which protect non-infected cells from further viral
infection.
(b) The yellowish fluid colostrum secreted by mother
during the initial days of lactation, has abundant
antibodies (IgA) to protect the infant from several
diseases during the initial six months.
(c) Antivenom against snake poison contains
antibodies. It is a biological product that typically
consists of venom neutralising antibodies derived
from a host animal, such as a horse or sheep. It is not
considered as antigen or antigen-antibody complex or
enzyme.
(b) Statements II and IV show the correct reasons for
rheumatoid arthritis. It is an autoimmune disorder.
Autoimmunity is an abnormal immune response in
which the immune system of the body starts rejecting
its own body cells or ‘self’ cells and molecules.
This happens as the body loses its ability to
differentiate the pathogen or foreign molecules from
self cell and attacks self-cells damaging them.
(d) Thymus is not a secondary lymphoid tissue rather
it is a primary lymphoid organ in which origin and/or
maturation and proliferation of lymphocytes occur.
The secondary lymphoid organs such as spleen,
tonsils, appendix, lymph nodes provide sites for
interaction of lymphocytes with the antigen, which
then proliferate to becomes effector cells.
(c) The thymus is a lobed organ located near the
heart and beneath the breastbone. The thymus is
quite large at the time of birth but keeps on reducing
in size with age and by the time puberty is attained it
reduces to a very small size.
(c) Shaking hands with infected people is not a mode
of transmission of HIV. Rest of the other options all
indicate different modes of HIV transmission.
(c) The genes which cause cancer are called
oncogenes. Normal cells have genes called cellular
oncogenes or proto-oncogenes, which are present in
inactivated state, but under certain conditions (like
mutation) these get transformed to cancer causing
oncogenes.
(a) ‘Smack’ is obtained by acetylation of morphine,
extracted from the latex of poppy plant (Papaver
somniferum). Smack (also called heroin) is
chemically diacetyl morphine and is a white,
odourless, bitter, crystalline compound.
(a) Tobacco has nicotine, which stimulates the
adrenal gland to release adrenaline and
nor-adrenaline which in turn increases the blood
pressure and heart rate. For rest of the other options.
Tannic acid is a type of polyphenol used as a
modrant.
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Curcumin is a pain reliever.
Catechin derived from catechu is an antioxidant.
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CHAPTER > 09
Strategies for
Enhancement in
Food Production
NEET
KEY NOTES
Animal Husbandry
Å
It is the agricultural practice of breeding and raising
livestock like buffaloes, cows, pigs, horses, cattle, sheep,
camel, goat, etc.
Strict cleanliness and hygiene are important while milking,
storage and transport of the milk and its products.
Å
Regulator inspections for stringent up keep and proper
record maintenance.
Å
It includes poultry farming and fisheries.
Å
Regular visits by a doctor would be mandatory.
Å
Fisheries include rearing, catching, selling, of fish, molluscs
(shell-fish) and crustaceans (prawns, crabs, etc).
Poultry Farm Management
Å
More than 70% of worlds livestock population is in India and
China. However, its contribution to the world farm produce
is only 25%.
Å
Management of Farms and Farm
Animals
Å
Poultry is the class of domesticated fowl (birds) used for
food or their eggs.
Å
It mainly includes chicken and ducks and sometimes turkey
and geese.
Å
Important components of poultry farm management include
Practices employed to enhance food production from animals
targeted management of farm and farm animals such as dairy
farm management and poultry farm management.
Dairy Farm Management
Å
Dairying is the management of animals for its milk and its
product for human consumption. In dairy farm
management, we deal with processes and systems that
increase yield and improve quality of milk.
Å
Selection of good breeds having high yielding potential,
combined with resistance to diseases is very important.
Å
Cattles have to be housed well, should have proper water
and be maintained disease free.
Å
The feeding of cattle should be carried out in a scientific
manner (quality and quantity of fodder).
Å
n
Selection of disease free and suitable breeds
n
Proper and safe farm condition
n
Proper feed and water
n
Hygiene and healthcare
A viral infection affecting poultry birds is bird flu. It is
caused by infection with bird flu virus or H5 N1 virus. It is
deadly to birds and can easily affect humans through
consumption of their products (eggs, meat, etc) and other
animals that come in contact with a carrier.
Animal Breeding
Å
It aims at increasing yields of animals and improving the
desirable qualities of the product.
Å
A breed is a group of animals related by descent and similar
in most of characters like general appearance, features, size,
configuration, etc.
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Master The NCERT > BIOLOGY (Vol-II)
220
Å
There are two kinds of breeding, i.e. inbreeding (breeding
between same breeds) or outbreeding (breeding between
different breeds).
Inbreeding
Å
Å
Å
Å
Outbreeding
Method of mating of more closely
related individuals within the
same breed, i.e. superior males
and superior females of the same
breed for 4-6 generations.
Method of mating of unrelated
animals for 4-6 generations. It is
of three types, i.e. outcrossing,
cross-breeding and interspecific
hybridisation.
Advantages It increases
homozygosity, so it is used for
developing purelines. It exposes
harmful recessive genes that are
eleminated by selection. It also
helps in accumulation of superior
genes and elimination of less
desirable genes.
Advantages It produces hybrids
with desirable characters of both
the parents like better lactation
period and high milk productions.
Continued inbreeding reduces fertility and even
productivity. This is called inbreeding depression.
Whenever this becomes a problem. Selected animals of the
breeding population should be mated with unrelated
superior animals of the same breed. This usually helps to
restore fertility and yield.
Outcrossing is the mating of animals within same breed but
having no common ancestors up to 4-6 generations. The
offspring are called outcross. This method helps in
increasing the milk production, growth rate in beef cattle etc.
Cross-breeding is the mating of superior male of one breed
with the superior female of another breed. The progeny
formed by this, may themselves be used for the commercial
production or alternatively used to develop new superior
breeds.
The genetic mother becomes available for another round
of superovulation. High milk-yielding breeds of
females and high quality (lean meat with less lipid)
meat- yielding bulls have been bred successfully this
technique to increases a herd size in short time.
Bee-keeping
Å
A remarkable growth in the practice of bee-keeping or
apiculture has been observed as it is a old cottage
industry requiring less manpower and management
skills. Also,demand for its products honey (high
nutritive value and indigenous medicine) and beeswax
(used in the preparation of cosmetics and polishes) has
increased significantly.
Å
Bee-keeping can be practiced in any area where
sufficient pasture is available. The most common species
of honybee is Apis indica.
Å
Few points are important for successful bee-keeping
like-knowledge of the nature and habits of bees,
selection of suitable location for beehives, catching and
hiving of swarms, management of beehives during
different seasons and proper handling and collection of
honey and beeswax.
Fisheries
Å
Fishery is another flourishing industry meeting the
ever-increasing demand for fish, fish products and other
aquatic foods. It includes catching, processing and
marketing of fishes.
Å
Freshwater fishes which are very common include catla,
rohu and common carp.
Common marine fishes are hilsa, sardines, mackerel and
pomfrets and selling of fish, shellfish and other aquatic
animals.
Å
By this technique, Hisardale (a new breed of sheep)
developed in Punjab by crossing Bikaneri ewes and Marino
rams.
Å
Å
Interspecific hybridisation is the mating of male and female
animals of two different related species. The progeny may be
of considerable economic value, e.g. mule.
Å
This industry provides employment to millions of
fisherman and farmers particularly in the coastal states.
Å
Different techniques have been applied to increase the
production of aquatic plants and animals such as
aquaculture and pisciculture.
Å
Blue revolution is implemented to increase fish
production.
Å
Å
Å
To improve the chances of successful production of hybrids,
controlled breeding methods such as MOET (Multiple
Ovulation Embryo Transfer) technique and artificial
insemination are applied. These methods have given better
results than the conventional selective hybridisation.
In artificial insemination, the semen is collected from the
male and injected into the reproductive tract of the selected
female. In this way, desirable matings are carried and it
helps us to overcome several problems of normal matings.
In MOET, cow is administered with FSH hormone, to induce
follicular maturation and superovulation and instead of 1,
they produce 6-8 eggs. After mating, all these fertilised eggs
at 8-32 cell stage are collected and transferred to surrogate
mothers.
NEET
Plant Breeding
Å
India‘s economy is based on agriculture and nearly
62% of the population is employed in this sector at
various levels. As only limited land is fit for cultivation,
India has to strive to increase yields per unit area from
existing farm lands.
Å
Plant breeding techniques led to a dramatic increase in
food production in 1960. This is often referred to as the
green revolution.
KEY NOTES
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CHAPTER 09 > Strategies for Enhancement in Food Production
What is Plant Breeding?
n
n
Å
Plant breeding involves purposeful manipulation of plant
species used to create varieties, which have increased crop
yield, improved quality, increased tolerance to environmental
stresses (extreme temperatures, salinity, drought), resistant to
pathogens and to insect pests. Eventually, achieving the goal
of increase in the yield of the food.
Å
Plant breeding programmes are carried out in a systematic
way. The main steps in plant breeding are
1. Collection of variability is the collection and
preservation of all the different wild varieties, species
and relatives of the cultivated species. The entire
collection of plants or seeds having all the diverse alleles
for all genes in a given crop is called germplasm
collection.
2. Evaluation and selection of parents is the identification
of plants with desirable characteristics. The selected
plants are multiplied and used in hybridisation process.
3. Cross hybridisation among the selected parents to
obtain desired crop characters, e.g. high protein quality
of one parent combined with disease resistance from
another parent. This is possible by cross hybidising the
two parents to produce hybrids that have genetically
combined characters in one plant.
4. Selection and testing of superior recombinants is the
selection of the plant having desired character
combination. This step requires scientific evaluation of
the progeny and yield plants that are superior to both of
the parents. These are self- pollinated for several
generations till they become uniform or homozyous.
5. Testing, release and commercialisation of new cultivars
The newly selected lines are evaluated for their yield and
other agronomic traits (of quality, disease resistance, etc.)
by
growing these in the research fields and
recording their performance under ideal fertiliser application,
irrigation and other crop management practices.
Final step involves testing the generated varieties in
farmer’s fields, for at least three growing seasons, at
several locations in the country, representing all the
agroclimatic zones, where the crop is usually grown.
Å
Hybrid varieties of crop plants, developed in India are
n
n
Wheat Varieties such as Sonalika and Kalyan Sona are
high yielding and disease resistant.These were derived
from semidwarf variety developed by Nobel laureate
Norman E Borlaug, at International Centre for Wheat and
Maize Improvement (CIMMYT) in Mexico.
Rice Semidwarf rice varieties were derived from IR-8
[developed at International Rice Research Institute (IRRI),
Philippines] and Taichung Native-1 (from Taiwan).
Jaya and Ratna were developed in India.
n
n
Sugarcane Saccharum barberi of North India had poor
sugar content and yield. Tropical canes grown in
South India Saccharum officinarum had thicker stems
and higher sugar content but did not grow well in
North India.
These two species were crossed to get sugarcane
varieties with high yield, thick stems, high sugar
content and ability to grow in North India.
Millets Hybrid varieties of maize, jowar and bajra
that are high yielding and resistant to water stress
have been developed in India.
Plant Breeding for Disease
Resistance
Å
Fungal, bacterial and viral infections in cultivated crop
species reduce the crop yield up to 20-30%, especially in
tropical climates.
Å
To reduce infections and to cut down the use of
fungicides and bactericides, disease resistant varieties
need to be developed.
Å
Resistance of the host plant is the ability to prevent the
pathogen from causing disease and is determined by the
genetic constitution of the host plant.
Some of the diseases caused by various pathogens
are
n
Fungi Brown rust of wheat, red rot of sugarcane and
late blight of potato.
n
Bacteria Black rot of crucifers.
n
Viruses Tobacco mosaic, turnip mosaic, etc.
Methods of Breeding for Disease
Resistance
Å
Conventional breeding The steps are
Screening germplasm for resistance sources.
Hybridisation of selected parents.
Selection and evaluation of the hybrids.
Testing and release of new varieties.
Some Important Varieties Developed
by Conventional Breeding
n
n
n
n
Crop
Variety
Resistance to diseases
Wheat
Himgiri
Leaf and stripe rust, hill bunt
Brassica
Pusa Swarnim
(Karan rai)
White rust
Cauliflower
Pusa Shubhra, Pusa
Snowball K-1
Black rot and curl blight
black rot
Cowpea
Pusa Komal
Bacterial blight
Chilli
Pusa Sadabahar
Chilli mosaic virus, Tobacco
mosaic virus and leaf curl.
NEET
KEY NOTES
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222
Å
Mutation breeding is the process of breeding by artificially
inducing mutations using chemicals or radiations (gamma
radiations).
Å
Mutation is the process by which base sequence within genes
changes, resulting in the creation of a new character or trait
not found in the parent plant, e.g.
n
n
Å
The objective of breeding for improved nutritional
quality is to improve
n
n
n
Å
By using biofortification technique, we had developed
In mung bean, resistance to yellow mosaic virus and
powdery mildew were induced by mutations.
n
In bhindi (Abelmoschus esculentus), resistance to yellow
mosaic virus was transferred from a wild species to the
crop species by sexual hybridisation and a new variety of
A. esculentus called Parbhani kranti was produced.
n
n
Plant Breeding for Developing
Resistance to Insect Pests
n
n
Å
Insect and pest infestations are another major cause for large
scale destruction of crop plant and crop production.
Insect resistance in host crop plants may be due to
morphological, biochemical or physiological characteristics.
n
n
Morphological pest deterrents Hairy leaves in several
plants are associated with resistance to insect pests,
e.g. resistance to jassids in cotton and cereal leaf beetle in
wheat. Solid stems in wheat, is not preferred by the stem
sawfly, smooth leaved and nectar less cotton varieties do
not attract bollworms.
Biochemical pest deterrents High aspartic acid, low
nitrogen and sugar content in maize leads to resistance to
maize stem borers. Breeding methods for insect pest
resistance are same as for disease resistance. Sources of
resistance genes may be cultivated varieties, germplasm
collections of the crop or wild relatives.
Some Crop Varieties Breed by Hybridisation
and Selection, for Insect Pest Resistance
Crop
Variety
Insect pests
Brassica
(rapeseed mustard)
Pusa Gaurav
Aphids
Flat bean
Pusa Sem 2 and Pusa
Sem 3
Jassids, aphids and
fruit borer
Pusa Sawani and Pusa
A-4
Shoot and fruit borer
Okra (bhindi)
n
n
Å
More than 840 million peoples in the world do not have
adequate food to meet their nutritional and daily food
requirements and about these billion people suffer from
micronutrient, protein and vitamin deficiencies, i.e. hidden
hunger.
Biofortification is the method of breeding crops with higher
levels of vitamins, minerals and healthier fats to improve
public healths.
NEET
Maize hybrids with twice the amount of the amino
acids, lysine and tryptophan, compared to existing
maize hybrids.
Wheat variety, Atlas 66, having a high protein
content.
An iron-fortified rice variety with five times higher
iron content than in commonly consumed varieties.
Vitamin-A enriched carrots, spinach, pumpkin.
Vitamin-C enriched bitter gourd, bathua, mustard,
tomato.
Iron and calcium enriched spinach and bathua.
Protein enriched beans - broad, lablab, French and
garden peas.
The Indian Agricultural Research Institute, New
Delhi has released above mentioned vegetable crops
rich in vitamins and minerals.
Single Cell Protein (SCP)
Å
It refers to the source of mixed proteins extracted from
pure or mixed culture of organisms or cells.
It acts as a supplement or alternative source of protein
that is not supplied by the traditional of conventional
agriculture production.
Å
Several microbes have also been used as source of good
proteins. Microbes like Spirulina and Methylophilus
methylotrophus are being grown on an industrial scale on
materials like waste water from potato processing plants
(containing starch), straw, molasses, animal manure and
even sewage.
Å
Advantages of SCP
n
n
Plant Breeding For Improved Food
Quality
Å
protein and oil content and quality
vitamin content.
micronutrients and mineral content.
Using waste as nutrient medium reduces
environmental pollution.
Because of their high rate of biomass production and
growth, microbes can produce much bigger amount
of protein than the larger animals, e.g. 250 gm of
Methylophilus methylotrophus produces 25 tonnes of
proteins.
Tissue Culture
Å
As traditional breeding techniques were slow new
technology called tissue culture was developed as a fast
and efficient systems for crop improvement.
Å
Plants have a special property called totipotency which
is the capacity to generate a whole plant from any cell.
KEY NOTES
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CHAPTER 09 > Strategies for Enhancement in Food Production
Å
Plants can be regenerated in lab from explants, i.e. any part of
a plant taken out and grown in a test tube, under sterile
conditions in special nutrient media.
Å
The nutrient medium must provide, a carbon source such as
sucrose, inorganic salts, vitamins, amino acids and growth
regulators like auxins and cytokinins.
Å
Micropropagation is the method of producing thousands of
plants through tissue culture.
Each of these plants will be genetically identical to the
original plant from which they were grown, i.e. they are
somaclones.
Many important food plants like tomato, banana, apple, etc.,
have been produced on commercial scale using this method.
Å
Å
Another application of tissue culture method is the
recovery of healthy plants from diseased plants. Even when
the plant is infected with a virus, the meristem (apical and
axillary) remains infection free; it can be removed, grown
in vitro to obtain virus-free plants. Meristems of banana,
sugarcane, potato, etc., have been isolated.
Somatic hybridisation is the process of in vitro fusion of
protoplasts of somatic cells obtained from different
varieties or species of plants on a suitable nutrient medium
to develop a hybrid. In this process, first the cell wall of
plant cells are removed.
The protoplasts of these cells are allowed of fuse in the
presence of PEG. Later, the fused protoplasts develop thin
own walls and are called as somatic hybrids, e.g. pomato.
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1
~ Animal Husbandry, Management
of Farms and Farm Animals
1 …… is the agricultural practice of feeding, breeding
6 The management of animals for milk and its
and raising livestock. Choose the most appropriate
word to fill in the blank.
products for human consumption is called
(a)
(b)
(c)
(d)
Animal husbandry
Cattle improvement
Both (a) and (b)
Cattle farming
(b) poultry farming
(d) All of these
3 Crustacean fishery is connected with exploitation of
(a)
(b)
(c)
(d)
oysters and crabs
mussels and squids
shell and cuttle fish
crabs and prawn
4 Livestock refers to
(a)
(b)
(c)
(d)
pet animals
poultry and pet animals
domestic animals which are kept for use or profit
None of the above
5 The practices concerned with the improvement in
animal husbandry include
(a)
(b)
(c)
(d)
(b) poultry farming
(d) livestock improvement
7 In dairy farm management
2 Animal husbandry includes
(a) fisheries
(c) dairying
(a) dairy farming
(c) white revolution
management of farm and farm animals
management of animals and plants at a same place
genetic engineering
None of the above
(a)
(b)
(c)
(d)
livestock improvement is done
milk yield and quality is improved
regular inspection of animals
All of the above
8 Choose the correct option.
(a) More than 70% of the world livestock population is in
India and China
(b) The contribution of India and china to the world farm
produce is about 25%
(c) Important livestock of India are cattle and buffaloes
(d) All of the above
9 Which of the following qualities is considered for
the selection of good breeds?
(a) High yielding potential
(c) Breed with pureline
(b) Resistance to diseases
(d) Both (a) and (b)
10 What measures should be taken for cattles, to
realise the yield potential?
(a)
(b)
(c)
(d)
They have to be housed well
Feeding should be in scientific manner
Hygienic milking, storage and transport of milk
All of the above
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224
11 Which of the following birds are domesticated in
14
poultry farm management?
(a) Chicken
(c) Turkey and geese
(b) Ducks
(d) All of these
12 Which of the following points should be kept into
consideration for management of poultry farm?
A. Selection of disease free and suitable breeds
B. Proper and safe farm conditions
C. Proper feed and water
D. Hygiene and healthcare
(a) A,B,C
(b) A,C,D
(c) A,B,C,D
(d) None of these
13 Bird flu is a ………… disease.
(a) viral
(c) fungal
(b) bacterial
(d) algal
Identify improved breed shown in diagram.
(a) A–Jersey, B–Leghorn (b) A–Surti, B–Sangamneri
(c) A–Marwari, B–Sirohi (d) A–Beetal, B–Jamunapari
15 An infectious bacterial disease of cattle, buffaloes,
sheeps and goats is
(a) anthrax
(c) tick fever
(b) rinderpest
(d) necrosis
TOPIC 2 ~ Animal Breeding, Bee-keeping and Fisheries
16 Which of the following is an aim of animal
breeding?
(a)
(b)
(c)
(d)
Increasing the yield of animals
Improving the desirable qualities of the produce
Producing better looking animals
Both (a) and (b)
17 The term ‘breed’ refers to
(a) a group of animals not related by descent but similar in
most characteristics
(b) a group of animals related by descent and similar in
most characteristics
(c) a group of animals related by descent but have almost
different characteristics
(d) a group of animals neither related by descent nor have
similar characteristics
18 The term ‘inbreeding’ refers to
(a) mating of more closely related individuals within the
same breed for 4-6 generations
(b) mating of unrelated animals of the same breed
(c) mating of animals within the same breed, but having no
common ancestors up to 4-6 generations
(d) superior males of one breed are mated with superior
females of another breed
19 A superior female, in the case of cattle is the …A…
that produces more milk per lactation. On the other
hand, a superior male is the …B…, which gives rise
to …C… as compared to those of other males. Here,
A to C refers to
(a)
(b)
(c)
(d)
A–cow, B–bull, C–superior progeny
A–buffalo, B–bull, C–inferior progeny
A–cow, B–bull, C–inferior progeny
A–cow, B–bull, C–normal progeny
20 Continued inbreeding
(a) reduces fertility
(b) reduces productivity
(c) causes inbreeding depression
(d) All of the above
21 Homozygous purelines in cattle can be obtained by
NEET 2017
(a) mating of related individuals of same breed
(b) mating of unrelated individuals of same breed
(c) mating of indviduals of different breed
(d) mating of individuals of different species
22 Suggest a way to overcome inbreeding depression.
(a) Selected animals should be mated with related superior
animals of different breed
(b) Selected animals should be mated with unrelated
superior animals of same breed
(c) Selected animals should be mated with related superior
animals of same breed
(d) Selected animals should be mated with unrelated
superior animals of different breed
23 Outbreeding is an important strategy of animal
husbandry because it
CBSE-AIPMT 2015
(a) helps in accumulation of superior genes
(b) is useful in producing purelines of animals
(c) is useful in overcoming inbreeding depression
(d) exposes harmful recessive genes that are eliminated by
selection
24 When breeding is between the unrelated animals,
including individuals of the same breed but having no
common ancestors for 4-6 generations or between
different breeds or different species, is called
(a) outbreeding
(c) controlled breeding
(b) inbreeding
(d) hybridisation
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CHAPTER 09 > Strategies for Enhancement in Food Production
25 Hissardale is a new breed of …A… developed in
Punjab by crossing …B… and …C… .
Here A to C refers to
(a)
(b)
(c)
(d)
A–sheep, B–Bikaneri ewes, C–Marino rams
A–chicken, B–Dorking, C–Sussex
A–chicken, B–Leghorn, C–Plymouth rock
A–cow, B–Jersey, C–Brown Swiss
26 Interspecific hybridisation is the mating of NEET 2016
(a) animals within same breed without having common
ancestors
(b) two different related species
(c) superior males and females of different breeds
(d) more closely related individuals within same breed for
4-6 generations
33 Fill up the blanks.
I. …… A ……refers to the cross of superior males of one
breed with superior females of another breed.
II. …… B …… is a method of controlled breeding in
which semen from the selected male parent is injected
into the reproductive tract of the selected female
parent.
III. …… C …… refers to crossing between male and
female animals of two different species.
IV. …… D …… is a programme for herd improvement in
animals like cattle, sheep, buffaloes, etc.
A
(a) MOET
27 A mule is produced by
(a)
(b)
(c)
(d)
cross-breeding
outcrossing
inbreeding
interspecific hybridisation
28 Controlled breeding experiments are carried out using
(a) interspecific hybridisation
(b) artificial insemination
(c) outcrossing
(d) intraspecific hybridisation
29 MOET stands for
(a)
(b)
(c)
(d)
Multiple Ovulation Embryo Transfer technology
Multiple Ovary and Embryo Transfer technology
Multiple Ovulation Embryo Test technology
Method of Egg Transfer
30 In MOET procedure, to induce follicular maturation
and superovulation which of the following hormones
are administered to the cow?
(a) Follicle stimulating hormone
(b) Progesterone
(c) Androgen
(d) Oxytocin
31 During MOET at which of the following stages,
embryo is transferred to surrogate mothers
(a)
(b)
(c)
(d)
Unfertilised ovules
2-celled stage
Fertilised egg
8-32 celled stage
32 In which of the following techniques high milk giving
breeds of females and high quality meat giving bulls
have been bred successfully to increase herd size
short time?
(a)
(b)
(c)
(d)
MOET
Artificial insemination
Interspecific hybridisation
Induced mutation
B
C
Interspecific Artificial
hybridisation insemination
(b) Cross-breeding Artificial
Interspecific
insemination hybridisation
(c) Artificial
insemination
MOET
(d) Interspecific
hybridisation
Artificial
MOET
insemination
D
Cross-breeding
MOET
Cross-breeding Interspecific
hybridisation
Cross-breeding
34 Rearing of honeybees for obtaining honey and
beeswax is called
(a) pisciculture
(c) apiculture
(b) sericulture
(d) aquaculture
35 Most common honeybee species in India
(a) Apis indica
(c) Apis mellifera
(b) Apis florea
(d) Apis dorsata
36 Which of the following given point is important for
successful bee-keeping?
(a) Knowledge of the nature and habits of bees
(b) Selection of suitable location for keeping the
beehives
(c) Catching and hiving of swarms (group of bees) and
their management during different seasons
(d) All of the above
37 Keeping beehives in crop field during flowering
period
(a)
(b)
(c)
(d)
improve honey and wax yield
improves crop yield
pollination efficiency
All of the above
38 Name the industry that includes catching, processing
or selling of aquatic animals.
(a) Fisheries
(c) Sericulture
(b) Apiculture
(d) None of these
39 Which of the following is not a freshwater fishes?
(a) catla
(c) common carp
(b) rohu
(d) mackerel
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Master The NCERT > BIOLOGY (Vol-II)
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40 Edible fishes found in marine water habitat is/are
(a)
(b)
(c)
(d)
42 Which of the following activities has contributed
towards increased production of aquatic organisms?
sardines
pomfrets
Hilsa
All of the above
41 Among the following edible fishes, which one is a
marine fish having rich source of omega-3 fatty
acids?
NEET 2016
(a) Mystus
(b) Magur
(c) Mrigala
(d) Mackerel
(a)
(b)
(c)
(d)
Pisciculture and sericulture
Pisciculture and aquaculture
Pisciculture and blue revolution
Blue and green revolution
43 The byproducts obtained from fisheries are
(a)
(b)
(c)
(d)
isinglass, oil, shagreen and fishmeal
eggs, meat, oil and leather
isinglass and eggs
None of the above
TOPIC 3 ~ Plant Breeding and Single Cell Protein
44 Green revolution in India was possible due to
(a)
(b)
(c)
(d)
exploitation of high yielding varieties
intensive cultivation
better irrigation, fertilisers and pesticide facilities
All of the above
45 Green revolution depended mainly on plant breeding
techniques for high yielding and disease resistant
varieties in
(a) wheat (b) rice (c) maize
(d) All of these
46 ……… is the purposeful manipulation of plant
species in order to create plant types that are better
suited for cultivation, give better yield and are disease
resistant. Fill up the blanks.
(a)
(b)
(c)
(d)
Aquaculture
Plant breeding
Animal husbandry
Apiculture
47 Following are the steps to produce a new genetic
variety of crop.
Collection of germplasm.
↓
A
↓
Cross-breeding /Hybridisation
↓
B
↓
Testing, release and commercialisation
of the new cultivars
Choose appropriate option for A and B.
(a) A–Selection of parents; B–Testing of superior
recombinants
(b) A–Evaluation of parents; B–Selection of superior
recombinants
(c) A–Testing of parents; B–Selection of superior
recombinants
(d) A–Evaluation and selection of parents; B–Selection and
testing of superior recombinants
48 Which of the following is considered as the root of
any breeding programme?
(a)
(b)
(c)
(d)
Genetic variability
Cross hybridisation
Hybrid vigour
Heterosis
49 In plant breeding programmes, the entire collection
(of plants/seeds) having all the diverse alleles for all
NEET 2013
genes in a given crop is called
(a) selection of superior recombinants
(b) cross-hybridisation among the selected parents
(c) evaluation and selection of parents
(d) germplasm collection
50 Which of the following is the main aim of evaluation
of germplasm in plant breeding programme?
(a) To identify plants with desirable combination of
characters
(b) For effective exploitation of the natural genes
(c) To look for harmful mutated gene
(d) For collection of variability
51 In case of plant breeding, cross hybridisation is a time
consuming and tedious process because
(a) pre-existing genetic variability is collected from wild
varieties, species and relatives of the cultivated crop
species
(b) it involves the selection of plants among the progeny of
the hybrids with desired combination of characters
(c) it involves emasculation and bagging techniques to
transfer desired pollen grains to the stigma of desired
plant
(d) None of the above
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CHAPTER 09 > Strategies for Enhancement in Food Production
63 Saccharum officinarum variety of sugarcane had
52 During selection and testing of superior
recombinants, selected superior plants are
self-pollinated for several generation. Why?
(a)
(b)
(c)
(d)
So that they reach a state of uniformity (homozygosity)
So that the characters will not segregate in the progeny
Both (a) and (b)
Selected superior plants are not self-pollinated but
cross-pollinated
53 After India independence, one of the main challenges
facing the country was
(a)
(b)
(c)
(d)
improving science and technology
producing enough food for increasing population
production of disease resistance varieties of crops
Both (b) and (c)
54 Semidwarf variety of wheat was developed by
(a) Norman E Borlaug
(c) WY Cheung
(b) MS Swaminathan
(d) Fontana
55 Semidwarf variety of wheat was developed at
(a) International Centre for Wheat and Maize Improvement
Brazil
(b) International Centre for Wheat and Maize Improvement
Mexico
(c) International Centre for Wheat and Rice Improvement
Japan
(d) International Centre for Wheat and Gram Improvement
Mexico
56 Example of high yielding and disease resistant wheat
variety is
(c) Ratna
(d) Jaya
57 Semidwarf varieties of rice were derived from
IR-8 and Taichung Native-I
Atlas 66
Kalyan Sona
Jaya and Ratna
situated at
(a) New York (USA)
(b) Tokyo (Japan)
(c) Manilla (Philippines) (d) Hyderabad (India)
59 Where Taichung Native-1 was developed?
(b) Tokyo
(c) Tallinn
(d) Taiwan
60 Jaya and Ratna are varieties of
(a) maize
64 The genetic ability of a plant to prevent pathogens
from causing disease is called
(a) resistance
(c) pathology
(b) wheat
(c) rice
(d) millet
61 Saccharum barberi and Saccharum officinarum are
varieties of
(a) sugarcane (b) maize
(c) wheat
(d) rice
62 The sugarcane growing in North India and having a
65 Which one of the following is a bacterial disease?
(a)
(b)
(c)
(d)
Tobacco mosaic
Turnip mosaic
Black rot of crucifer
Late blight of potato
66 Hairy root disease of dicot plants is caused by
AIIMS 2019
(a) Agrobacterium tumefaciens
(b) Agrobacterium rhizogene
(c) Bacillus thuringiensis
(d) Meloidogyne incognita
67 Method(s) of breeding plants for acquiring disease
resistance is/are
(a) conventional breeding techniques
(b) mutation breeding
(c) tissue culture
(d) Both (a) and (b)
68 The conventional method of breeding for disease
(a)
(b)
(c)
(d)
screening of germplasm for resistant sources.
hybridisation of selected parents.
induction of mutation.
Both (a) and (b)
disease resistance against rust pathogens is a
variety of
(a) chilli
(c) sugarcane
Saccharum officinarum
Saccharum barberi
Both (a) and (b)
None of the above
(b) maize
(d) wheat
70 Some crop varieties bred by hybridisation and
selection for disease resistance to fungi, bacteria and
viral disease are shown below. Fill up the blanks
A to D.
Crop
Variety
Resistance to
diseases
A
Himgiri
Leaf and stripe rust,
hill bunt
Brassica
Pusa Swarnim (Karan rai)
B
Cauliflower
Pusa Shubhra, Pusa
Snowball K-1
Black rot and curl
blight black rot
Cowpea
C
Bacterial blight
Chilli
D
Chilli mosaic virus,
tobacco mosaic
virus and leaf curl
poor sugar content and yield is
(a)
(b)
(c)
(d)
(b) prevention
(d) None of these
69 Himgiri developed by hybridisation and selection for
58 International Rice Research Institute (IRRI) is
(a) Taraiva
thin stems and higher sugar content
thick stems and higher sugar content
thick stems and poor sugar content
thin stems and poor sugar content
resistance includes
(a) Sonalika (b) IR-8
(a)
(b)
(c)
(d)
(a)
(b)
(c)
(d)
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Master The NCERT > BIOLOGY (Vol-II)
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(a) A–Wheat, B–White rust, C–Pusa Komal, D–Pusa
Sadabahar
(b) A–Pusa Sadabahar, B–Black rust, C–Pusa Komal,
D–Wheat
(c) A–Rice, B–White rust, C–Pusa Karan, D–Wheat
(d) A–Maize, B–Brown rust, C–Pusa Karan, D–Millet
71 Triticale is the first man-made cereal crop.
Mention the type of hybridisation through which it
AIIMS 2018
was produced
(a)
(b)
(c)
(d)
intervarietal hybridisation
interspecific hybridisation
intergeneric hybridisation
intravarietal hybridisation
Spray with bordeaux mixture
Use of disease-free seeds only
Use of varieties resistant to the disease
All of the above
73 The process by which genetic variations are created
through changes in the base sequences within genes is
(b) interspecific hybridisation
(d) mutation
74 The process of breeding by artificially inducing
mutations with chemicals or radiations is called
(a) artificial breeding
(c) synthetic breeding
(b) chemical breeding
(d) mutation breeding
75 In mutation breeding, mutations are induced by using
radiation like
(a) Gamma rays
(c) UV-rays
(b) X-rays
(d) All of these
76 In mung bean, resistance to yellow mosaic virus and
powdery mildew were brought about by
NEET (Odisha) 2019
(a)
(b)
(c)
(d)
mutation breeding
biofortification
tissue culture
hybridisation and selection
77 Resistance to yellow mosaic virus in bhindi was
transferred from a wild species and resulted in new
variety of A. esculentus called
(a) Golden Kranti
(c) IR-8
(b) Sonalika
(d) Parbhani Kranti
78 The host crop plants may be resistant to insect pests
due to the
(a) morphological characteristics
(b) biochemical characteristics
(c) physiological characteristics
(d) All of the above
(a) insect pests
(c) virus
(b) bacteria
(d) bollworm
80 Solid stem in wheat exhibits non-preference by
(a)
(b)
(c)
(d)
jassids
fruit borer
stem borer
stem sawfly
(a) sawfly
(c) beetle
to successfully grow chickpea in an area where
bacterial blight is common.
AIIMS 2018
(a) plant breeding
(c) outcrossing
resistance to …… .
81 In cotton, smooth leaf and the absence of nectar repel
72 Consider the following measures that could be taken
(a)
(b)
(c)
(d)
79 Hairy leaves of many plants are associated with
(b) bollworms
(d) jassids
82 In maize, the presence of high aspartic acid, low
nitrogen and sugar content protect them from
(a)
(b)
(c)
(d)
aphids
fruit borers
jassids
stem borers
83 Some released crop varieties bred by hybridisation
and selection, for insect pest resistance are given in
the table. Fill up the blanks.
Crops
Varieties
Brassica
Insect pests
Aphids
A
B
Pusa Sem 2, Pusa Sem-3
Jassids, aphids and fruit
borer
C
Pusa Sawani, Pusa A-4
Shoot and fruit borer
(a)
(b)
(c)
(d)
A–Pusa Karan, B–Flat bean, C–Bhindi
A–Pusa Gaurav, B–Flat bean, C–Okra
A–Pusa Shubhra, B–Wrinkled bean, C–Pea
A–Pusa Komal, B–Smooth bean, C–Bhindi
84 Which of the following are not disease resistant
varieties?
(a) Pusa Gaurav
(c) Pusa Sawani
(b) Pusa Sem-2
(d) All of these
85 Hidden hunger is best indicated as
(a) inability of majority of people to buy enough fruits,
vegetables, legumes, fish and meat and thus suffer from
deficiency of vitamin, protein, etc.
(b) people are unable to buy healthy drink item and thus
suffer from deficiency
(c) people are unable to buy junk food thus suffer from
deficiency
(d) All of the above
86 Majority of people suffer from malnutrition because
their food does not contain essential micronutrients
specially
(a) iron
(c) vitamin-A
(b) iodine and zinc
(d) All of these
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CHAPTER 09 > Strategies for Enhancement in Food Production
87 The deficiency of essential micronutrients in food
may
I. increase risk for disease.
II. reduce mental ability.
III. reduce lifespan.
Choose the correct option.
(a) I, II and III
(c) Only I
(a) I, II and IV
(c) II, III and IV
human nutrition is
(a)
(b)
(c)
(d)
(b) I and III
(d) I and II
animal and human nutrition formed from certain
beneficial microorganisms like
for improved nutritional quality?
Improve protein and oil content and quality
Improve content of micronutrients and minerals
Improved vitamin content
All of the above
90 A biofortified wheat variety is
(a) Altas 66
(c) Kalyan Sona
single cell protein
proteomix
double cell protein
All of these
93 Single cell protein is an alternative protein source for
crops with increased yield
crops with disease resistance
herbicide resistant crops
crops with high nutritive value
89 What objectives are undertaken during crop-breeding
(a)
(b)
(c)
(d)
(b) All of these
(d) None of these
92 One of the alternate sources of protein for animal and
88 Biofortified crops are
(a)
(b)
(c)
(d)
Choose the correct option.
(b) IR-8
(d) Sonalika
(a)
(b)
(c)
(d)
Spirulina
Methylophilus methylotrophus
Both (a) and (b)
None of the above
94 Microbes like Spirulina, can also be grown on
industrial scale as source of good
(a) fat
(c) minerals
(b) carbohydrate
(d) All of these
95 Single cell protein reduces
91 The Indian Agricultural Research Institute, New
Delhi has released several fortified vegetable crops
that are rich in vitamins and minerals. They are
I. Vitamin-A enriched carrot, spinach, pumpkin.
II. Vitamin-C enriched bitter gourd, bathua, mustard and
tomato.
III. Iron and calcium enriched spinach and bathua.
IV. Protein enriched broad beans, French bean, garden
pea.
(a)
(b)
(c)
(d)
environmental pollution
greenhouse effect
global warming
production and growth of crop
96 250 g of Methylophilus methylotrophus bacterium has
been used to produce
(a)
(b)
(c)
(d)
15 tonnes of proteins
25 tonnes of proteins
35 tonnes of proteins
50 tonnes of proteins
TOPIC 4~ Tissue Culture
97 The technique of regeneration of whole plant from
any part of a plant by allowing it to grow on a suitable
culture under aseptic sterile conditions in vitro is
called
(a)
(b)
(c)
(d)
tissue culture
plant culture
micropropagation
somatic hybridisation
(a) Hormones like auxin, cytokinin, agar-agar AIIMS 2019
(b) Inorganic salt, vitamin, amino acid only
(c) Carbon source like sucrose only
(d) All of the above
101 To meet the demands of the society, in vitro
98 Which one is used in tissue culture?
(a) Explant
(c) Hybridisation
100 What are the requirements in tissue culture?
JIPMER 2018
(b) Somaclones
(d) None of these
99 The capacity of a cell explant to grow into a whole
production of a large number of plantlets in a short
duration is practiced in floriculture and horticulture
industry today. It is called
(a) somatic hybridisation (b) micropropagation
(c) hybridoma technology (d) somaclonal variation
102 A technique of micropropagation is
plant is called
(a) callus
(c) cellular totipotency
CBSE-AIPMT 2015
(b) tissue culture
(d) All of these
(a) somatic hybridisation
(c) protoplast fusion
(b) somatic embryogenesis
(d) embryo rescue
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230
103 The plants produced from tissue culture are
108 Somatic hybrids are produced by the fusion of …… .
genetically identical to the original plant from which
they are grown so they are called
(a) somaclones
(c) para clones
(b) clones
(d) None of these
104 Virus free plants can be formed by
(a) meristem culture
(c) somatic cell culture
(a)
(b)
(c)
(d)
AIIMS 2019
109 The embryo which develops from somatic cell is called
(b) callus culture
(d) protoplast fusion
(a)
(b)
(c)
(d)
105 Meristem culture is practiced in
(a) floriculture
(c) horticulture
(b) aquaculture
(d) pisciculture
protoplasts of two cells
cytoplasm of two cells
nucleus of two cells
DNA of two cells
somatic embryo
reproductive embryo
sterile embryo
None of the above
110 The process of fusion of protoplast of somatic cells
one by tissue culture technique, which part/parts of
the diseased plant will be taken? CBSE-AIPMT 2014
obtained from different varieties or species of plant
on a suitable nutrient medium in vitro to develop a
somatic hybrid is called
(a) Apical meristem only
(b) Palisade parenchyma
(c) Both apical and axillary meristems
(d) Epidermis only
(a)
(b)
(c)
(d)
106 To obtain virus-free healthy plants from a diseased
107 A protoplast is a cell
CBSE-AIPMT 2015
somatic hybridisation
cross hybridisation
intravarietal hybridisation
interspecific hybridisation
111 Pomato is a somatic hybrid of
(a) potato and onion
(c) potato and brinjal
(a) without plasma membrane (b) without nucleus
(c) undergoing division
(d) without cell wall
(b) potato and tomato
(d) brinjal and tomato
NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
114 Assertion (A) Interspecific crosses are rare in nature
■ Direction (Q. Nos. 112-121) In each of the following
questions, a statement of Assertion (A) is given followed
by corresponding statement of Reason (R).
Of the statements, mark the correct answer as
(a) If both A and R are true and R is the correct explanation of
A
(b) It both A and R are true, but R is not the correct
explanation of A
(c) If A is true, but R is false
(d) If A is false, but R is true
115
116
112 Assertion (A) Bird flu disease is the disease of poultry.
Reason (R) It is caused by a bacterium.
113 Assertion (A) In tissue culture, whole plant can be
produced from any plant cell.
Reason (R) Plant cells possess totipotency which
allow any viable plant cell to differentiate into
somatic embryo that can give rise to different cells of
plants.
117
118
and intergeneric crosses almost unknown.
Reason (R) Interspecific cross combine undesirable
features of both the parents.
Assertion (A) Protoplast culture is an important
technique of somatic hybrids.
Reason (R) Protoplast culture technique results in the
production of somatic hybrids.
Assertion (A) Virus-free plants can be produced by
meristem tissue culture.
Reason (R) In virus infected plant, only apical
mesistem is free of virus.
Assertion (A) Inbreeding produces pureline.
Reason (R) It causes homozygosity.
Assertion (A) Hybrid vigour (heterosis) is the
phenotypic superiority of hybrid over both of its
parents.
Reason (R) Characters of both the parents get
expressed in the hybrid progeny.
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CHAPTER 09 > Strategies for Enhancement in Food Production
119 Assertion (A) Biofortification is the most practical
approach to improve the health of the people
suffering form hidden hunger.
Reason (R) Biofortification is used to increase
nutrient value of crops.
120 Assertion (A) Aquaculture practice is economically
very beneficial.
Reason (R) It involves breeding, rearing, harvesting
and management of useful aquatic plants and animals.
121 Assertion (A) Light is an essential component of
poultry farm management.
Reason (R) Exposure to 14-16 hours of light ensures
optimum production of eggs.
II. Statement Based Questions
122 Select the incorrect statement.
NEET 2019
(a) Inbreeding is essential to evolve purelines in any
animals
(b) Inbreeding selects harmful recessive genes that reduce
fertility and productivity
(c) Inbreeding helps in accumulation of superior genes and
elimination of undesirable genes
(d) Inbreeding increases homozygosity
123 Select the incorrect statement regarding inbreeding.
NEET (Odisha) 2019
(a) Inbreeding helps in the elimination of deleterious
alleles from the population
(b) Inbreeding is necessary to evolve a pureline in any
animals
(c) Continued inbreeding reduces fertility and leads to
inbreeding depression
(d) Inbreeding depression cannot be overcome by
outcrossing
124 Mark the incorrect statement for inbreeding.
AIIMS 2019
(a)
(b)
(c)
(d)
Inbreeding depression increases productivity
Inbreeding depression can be overcome by outcrossing
Produces purelines
Increases homozygosity
125 Which of the following statements is correct for
cross-breeding?
(b) In case of artificial insemination, the semen can be used
immediately or can be frozen for later use
(c) Controlled breeding experiments are carried out using
artificial insemination and multiple ovulation embryo
transfer technology
(d) All of the above
127 Which of the following statements are not the main
objective of animal breeding?
(a)
(b)
(c)
(d)
Improved growth rate
Increased production of milk, meat, egg, wool, etc.
Superior quality of milk, meat, eggs, wool, etc.
Improved resistance to various diseases
128 Go through the given statements and choose the
correct statement.
(a)
(b)
(c)
(d)
Hilsa, sardines, mackerel are freshwater fishes
Catla and common carp are marine fishes
Blue revolution is concerned with fisheries
Both the term aquaculture and pisciculture are used for
rearing fishes only
129 Which of the following statements are correct?
(a) Hybrid breeding have led to the development of several
high yielding varieties resistant to water stress
(b) A group of animals related by descent and similar in
most characters are called a breed
(c) The agriculture practice of breeding and raising
livestock is called animal husbandry
(d) All of the above
130 Read the following statements. Choose the option for
correct statement.
(a)
(b)
(c)
(d)
Pusa Gaurav is a maize variety resistant to aphids
Pusa A-4 is okra variety resistant to aphids
Himgiri is a wheat variety resistant to hill bunt
Parbhani Kranti is resistant to rust disease
131 Which statements are correct about Atlas-66?
(a) It has high protein content
(b) It has been used as a donor for improving cultivated
wheat
(c) Both (a) and (b)
(d) Protina, Shakti and Rattan are three improved and
biofortified hybrids of Atlas-66
132 The parameters carried out for managing dairy farm
correct?
are
I. selection of both the male and female animals having
high yielding potential and resistance to diseases.
II. regular visits by a veterinary doctor.
III. each animal should be fed with a balance diet.
IV. pay attention to good animal management and general
supervision.
Which of the above statements are correct?
(a) The progeny of cross-breeding may be used for
commercial production
(a) I and II
(c) II, III and IV
(a) Refers to the cross of superior male of one breed with
superior female of another breed
(b) Is used to produce purelines
(c) Causes reduction in fertility
(d) Is best for amimals below average in milk productivity,
growth rate, etc.
126 Which of the following statements given below are
(b) I, II and III
(d) All of these
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133 Animal husbandry deals with
I. breeding of livestock buffaloes, cows, sheep, camels,
etc. that are useful to humans.
II. rearing, catching, selling, etc. of fish, molluscs and
crustaceans.
III. breeding plants for human use.
137 Read the given statements.
I. Beehives are mostly kept close to crop fields of
sunflower.
II. Bee-keeping is a labour-intensive method.
III. Beeswax is used in cosmetic industry.
IV. Apis indica is the most common bee species.
Which of the statements given above are correct?
Choose the incorrect statement.
(a) I and II
(c) II and III
(a) II and III
(c) Only IV
(b) I and III
(d) All of these
134 Consider the following statements (I-IV) and select
(b) Only II
(d) None of these
138 Read the given statements. Which of them are correct
the option which includes all the correct ones only.
I. Single cell Spirulina can produce large quantities of
food rich in protein, minerals, vitamins, etc.
II. Body weight-wise the microorganism Methylophilus
methylotrophus may be able to produce several times
more proteins than the cows per day.
III. Common button mushrooms are a very rich source of
vitamin-C.
IV. A rice variety has been developed which is very rich in
calcium.
CBSE-AIPMT 2012
about testing, release and commercialisation of new
cutlivars.
I. The newly selected lines are evaluated for their yield,
quality and disease resistance.
II. The evalution is done by recording their performance
under ideal fertiliser, irrigation, etc.
III. After evaluation, crops should be grown in farmer’s
fields for at least three growing seasons.
IV. The crop is evaluated in comparison to the best
available local crop cultivar.
(a) III and IV
(c) II, III and IV
(a) I and II
(c) Only I
(b) I, III and IV
(d) I and II
135 Strategic steps for inbreeding are
I. identify superior male and superior female of the same
breed.
II. identified animals are then mated in pairs.
III. evaluate the progeny obtained from the mating to
identify superior males and females.
IV. in cattle, superior female is the cow or buffalo that
produce more milk per lactation and superior male is
the bull that gives rise to superior progenies.
V. superior progenies obtained are further mated.
Arrange the above given steps in correct sequence
and select the correct answer.
(a)
(b)
(c)
(d)
I → III → II →IV → V
I → II → III → IV → V
III → I → II → IV → V
III → II → I → V → IV
136 Read the given statements about outcrossing.
I. It is the breeding between animals within the same
breed which do not have common ancestors on either
side of their pedigree up to 4-6 generations.
II. It is done to increase milk production and growth rate
in animals.
Which of the statement (s) given above is/are correct?
(a) Only I
(c) I and II
(b) Only II
(d) None of these
(b) I, II and III
(d) All of these
139 When the breeders want to incorporate desired
characters into the crop plants. They should
I. increase and improve yield.
II. increase tolerance to salinity.
III. resistance to pathogen viruses, fungi and bacteria.
IV. increased tolerance to insect pests.
Choose the correct option.
(a) I and II
(c) II, III and IV
(b) I, II and III
(d) All of these
140 Given below are four statements (I-IV). Which two of
the following statements are correct?
I. It is estimated that more than 70% of the world
livestock population is in India and China.
II. Maintaining cleanliness and hygiene (both of the cattle
and the handlers) is important while milking, storage
and transport of the milk and its products.
III. Outbreeding is the breeding between animal of the
same breed only.
IV. Crosses between different breeds are called
inbreeding.
Choose the correct option
(a)
(b)
(c)
(d)
I and II
III and IV
I and IV
II and III
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CHAPTER 09 > Strategies for Enhancement in Food Production
141 Mutation breeding is carried out by
I. inducing mutations in plants by high energy rays.
II. screening the plant for resistance.
III. selecting the desirable plant for multiplication and
breeding.
Choose the correct option.
(a) I and II
(c) II and III
(b) I and III
(d) All of these
142 Read the given statements.
I. High aspartic acid, low nitrogen and sugar content in
maize leads to resistance to maize stem borers.
II. Pusa Sadabahar is a food variety resistant to chilli
mosaic virus.
III. Norman E Borlaug developed a semidwarf variety of
wheat.
IV. Germplasm collection is the collection of all sexual
genes of an individual.
III. Matching Type Questions
145 Match the following columns.
Column I
(Category of animals)
Column II
(Examples)
A.
Meat animals
1.
Beef, sheep and cattle
B.
Poultry animals
2.
Cows and buffaloes
C.
Milk animals
3.
Chickens, turkeys and ducks
D.
Domesticated animal
4.
Horse and camels
Codes
A
(a) 1
(c) 2
B
3
4
C
2
1
D
4
3
A
(b) 3
(d) 4
B
2
1
C
4
3
D
1
2
146 Match the following columns.
Column I
(Breeding types)
Column II
(Features)
Choose the incorrect statements.
A. Outcrossing
(a) I and IV
(c) Only IV
1. Exposes harmful recessive genes that are
usually eliminated by selection
B. Cross-breeding
2. Mating of animals belonging to different
breeds
C. Interspecific
hybridisation
3 Mating of animals of same breed but
having no common ancestors on either
side of their pedigree for 4-6 generations
D. Inbreeding
4 Mating of animals of different species
(b) II and III
(d) II, III and IV
143 Which of the following statement (s) is/are correct?
I. The shift from grains to meat diets creates more
demand for cereals.
II. SCP provides a protein rich supplement.
III. SCP can be produced by using bacteria, blue- green
algae and fungi.
IV. SCP helps to minimise environmental pollution.
V. 3-10 kg of grains are required to produce 1 kg of meat
by animal farming.
Codes
A
(a) 1
(c) 3
I, II and III
Only III
Only IV
All of the above
144 Consider the following statements. Which of
them are the advantages of tissue culture/
micropropagation?
I. A large number of plants can be grown in short time.
II. Disease free plants can be recovered from diseased
plants.
III. Genetically variable plants can be produced.
IV. Somatic hybrids such as pomato can be raised.
Choose the correct option.
(a)
(b)
(c)
(d)
I, II and III
II, III and IV
I, II and IV
All of the above
C
3
4
D
4
1
A
(b) 4
(d) 2
B
3
4
C
2
3
D
1
1
147 Match the following columns.
Choose the correct option.
(a)
(b)
(c)
(d)
B
2
2
Column I
(Terms)
Column II
(Related to)
A.
Blue revolution
1. Fish
B.
Green revolution
2. Agriculture
C.
White revolution
3. Milk
Codes
A
(a) 1
(c) 3
B
2
2
C
3
1
A
(b) 2
(d) 1
B
3
3
C
1
2
148 Match the following columns.
Column I
(Terms)
Column II
(Features)
A.
Pisciculture
1.
Rearing of fishes
B.
Aquaculture
2.
Rearing and management of
economically useful aquatic plants
and animals
C.
Apiculture
3.
Concerned with maintenance of
honeybees
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234
Codes
A
(a) 3
(c) 2
152 Match the following columns.
B
2
1
C
1
3
A
(b) 2
(d) 1
B
3
2
C
1
3
Column I
(Plants)
149 Match the following columns.
Column I
(Breeding types)
Column II
(Used for)
A.
MOET
1.
It is done to increase milk
production, growth rate in beef cattle
B.
Interspecific
hybridisation
2.
For herd improvement
C.
Cross-breeding
3.
The progeny may be of considerable
economic value
D.
Outcrossing
4.
The progeny hybrid animals may be
used for commercial production
Codes
A
(a) 2
(b) 2
(c) 3
(d) 4
B
4
3
4
1
C
3
4
1
2
Column II
(Infectious agents)
A.
Brown rust of wheat
1.
Xanthomonas oryzae
B.
Bacterial blight
2.
Phytophthora infestans
C.
Red rot of sugarcane
3.
Puccinia graminis tritici
D.
Late blight of potato
4.
Colletotrichum falcatum
C
3
1
D
2
3
A
(b) 1
(d) 3
B
4
1
C
2
4
D
3
2
151 Match the following columns.
Column I
(Plants)
1.
Protein
Bitter gourd, mustard and tomato
2.
Iron and calcium
C.
Spinach and bathua
3.
Vitamin-C
D.
Broad bean, lablab, French-bean
and garden pea
4.
Vitamin-A
Codes
A
(a) 4
(b) 3
(c) 2
(d) 4
B
2
2
1
3
C
3
1
4
2
D
1
4
3
1
Wheat
1.
Pusa Sadabahar
B.
Cauliflower
2.
Pusa Komal
C.
Cow pea
3.
Pusa Shubhra
D.
Chilli
4.
Himgiri
Column II
(Improved variety name)
A.
Cotton
1. Erectiferum and Erectoids
B.
Rice
2. NP-836
C.
Wheat
3. Reimi and Jagannath
D.
Barley
4. Indore-2
Codes
A
(a) 1
(c) 3
B
2
4
C
3
1
D
4
2
A
(b) 4
(d) 2
B
3
1
C
2
4
D
1
3
154 Match the following columns.
Column I
(Organisations)
Column II
(Location)
A.
Indian Agricultural
Research Institute (IARI)
1.
Hyderabad
B.
International Crop
Research Institute for Semi
Arid Tropics (ICRISAT)
2.
New Delhi
C.
National Environmental
Engineering Research
Institute (NEERI)
3.
Shimla
D.
Central Potato Research
Institute (CPRI)
4.
Nagpur
Column II
(Name of improved variety)
A.
Codes
A
(a) 4
(b) 3
(c) 2
(d) 1
Carrot, spinach and pumpkin
B.
Column I
(Plants)
Column I
(Plant diseases)
B
1
4
A.
153 Match the following columns.
D
1
1
2
3
150 Match the following columns.
Codes
A
(a) 4
(c) 2
Column II
(Nutrient present)
Codes
B
3
2
1
4
C
2
1
4
3
D
1
4
3
2
(a)
(b)
(c)
(d)
A
4
2
3
1
B
2
1
2
2
C
1
4
1
3
D
3
3
4
4
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CHAPTER 09 > Strategies for Enhancement in Food Production
NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
155 The chances of contacting bird flu from a properly
163 Use of certain chemicals and radiation to change the
cooked (above 100° C) chicken and egg are
base sequences of genes of crop plants is termed
(a) very high
(b) high
(c) moderate
(d) negligible
(a) recombinant DNA technology
(b) transgenic mechanism
(c) mutation breeding
(d) gene therapy
156 A group of animals which are related by descent and
share many similarities are referred to as
(a) breed
(c) variety
(b) race
(d) species
157 Inbreeding is carried out in animal husbandry
because it
(a) increases vigour
(b) improves the breed
(c) increases heterozygosity
(d) increases homozygosity
(b) rice
(d) tobacco
159 Which one of the following is not a fungal disease?
(a) Rust of wheat
(c) Black rot of crucifers
enriched with certain desirable nutrients is called
(a) crop protection
(c) biofortification
(b) breeding
(d) bioremediation
165 Lysine and tryptophan are
(a) proteins
(b) non-essential amino acids
(c) essential amino acids
(d) aromatic amino acids
166 The term ‘totipotency’ refers to the capacity of a
158 Sonalika and Kalyan Sona are varieties of
(a) wheat
(c) millet
164 The scientific process by which crop plants are
(b) Smut of bajra
(d) Red rot of sugarcane
160 In virus-infected plants, the meristematic tissues in
both apical and axillary buds are free of virus
because
(a) the dividing cells are virus resistant
(b) meristems have antiviral compounds
(c) the cell division of meristems is faster than the rate of
viral multiplication
(d) viruses cannot multiply within meristem cell(s)
161 Several South Indian states raise 2-3 crops of rice
annually. The agronomic feature that makes this
possible is because of
(a) shorter rice plant
(b) better irrigation facilities
(c) early yielding rice variety
(d) disease resistant rice variety
162 Which one of the following combination would a
sugarcane farmer look for in the sugarcane crop?
(a) Thick stem, long internodes, high sugar content and
disease resistant
(b) Thick stem, high sugar content and profuse flowering
(c) Thick stem, short internodes, high sugar content,
disease resistant
(d) Thick stem, low sugar content and disease resistant
(a) cell to generate whole plant
(b) bud to generate whole plant
(c) seed to germinate
(d) cell to enlarge in size
167 An explant is
(a) dead plant
(b) part of the plant
(c) part of the plant used in tissue culture
(d) part of the plant that expresses a specific gene
168 The biggest constraint of plant breeding is
(a) availability of desirable gene in the crop and its wild
relatives
(b) infrastructure
(c) trained manpower
(d) transfer of genes from unrelated sources
169 Micropropagation is
(a) propagation of microbes in vitro
(b) propagation of plants in vitro
(c) propagation of cells in vitro
(d) growing plants on smaller scale
170 Protoplast is
(a) another name for protoplasm
(b) an animal cell
(c) a plant cell without a cell wall
(d) a plant cell
171 More than 70% of livestock population is in
(a) Denmark
(c) China
(b) India
(d) India and China
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177 Given below are a few statements regarding somatic
172 To isolate protoplast in plants, one needs
(a) pectinase
(c) Both (a) and (b)
(b) cellulase
(d) chitinase
173 Which one of the following is a marine fish?
(a) Rohu
(c) Catla
(b) Hilsa
(d) Common carp
174 The agriculture sector of India employs
(a) 50% of the population (b) 70% of the population
(c) 30% of the population (d) 60% of the population
hybridisation.
I. Protoplasts of different cells of the same plant are fused.
II. Protoplasts from cells of different species can be fused.
III. Treatment of cells with cellulase and pectinase is
mandatory.
IV. The hybrid protoplast contains characters of only one
parental protoplast.
Choose the correct option.
(a) I and II
175 33% of India’s Gross Domestic Product comes
(b) I and III (c) I and IV
(d) II and III
178 Fungicides and antibiotics are chemicals that
from
(a) enhance yield and disease resistance
(b) kill pathogenic fungi and bacteria, respectively
(c) kill all pathogenic microbes
(d) kill pathogenic bacteria and fungi, respectively
(a) industry
(b) agriculture
(c) export
(d) small-scale cottage industries
176 A collection of all the alleles of all the genes of a
crop plant is called
179 Which one of the following products of apiculture is
used in cosmetics and polishes?
(a) germplasm collection
(c) herbarium
(b) protoplasm collection
(d) somaclonal collection
(a) Honey
(c) Wax
(b) Porp oil
(d) Royal jelly
Answers
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1 (a)
2 (d)
3 (d)
4 (c)
5 (a)
6 (a)
7 (d)
8 (d)
9 (d)
10 (d)
11 (d)
12 (c)
13 (a)
14 (a)
15 (a)
16 (d)
17 (b)
18 (a)
19 (a)
20 (d)
21 (a)
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23 (c)
24 (a)
25 (a)
26 (b)
27 (d)
28 (b)
29 (a)
30 (a)
31 (d)
32 (a)
33 (b)
34 (c)
35 (a)
36 (d)
37 (d)
38 (a)
39 (d)
40 (d)
41 (d)
42 (b)
43 (a)
44 (d)
45 (d)
46 (b)
47 (d)
48 (a)
49 (d)
50 (a)
51 (c)
52 (c)
53 (b)
54 (a)
55 (b)
56 (a)
57 (a)
58 (c)
59 (d)
60 (c)
61 (a)
62 (b)
63 (b)
64 (a)
65 (c)
66 (b)
67 (d)
68 (d)
69 (d)
70 (a)
71 (c)
72 (d)
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74 (d)
75 (d)
76 (a)
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81 (b)
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85 (a)
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90 (a)
91 (b)
92 (a)
93 (c)
94 (d)
95 (a)
96 (b)
97 (a)
98 (a)
99 (c)
100 (d)
101 (b)
102 (b)
103 (a)
104 (a)
105 (a)
106 (c)
107 (d)
108 (a)
109 (a)
110 (a)
111 (b)
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112 (c)
113 (a)
114 (c)
115 (d)
116 (c)
117 (a)
118 (a)
119 (a)
120 (a)
121 (a)
122 (b)
123 (d)
124 (a)
125 (a)
126 (d)
127 (d)
128 (c)
129 (d)
130 (c)
131 (c)
132 (d)
133 (a)
134 (d)
135 (b)
136 (c)
137 (b)
138 (d)
139 (d)
140 (a)
141 (d)
142 (c)
143 (d)
144 (c)
145 (a)
146 (c)
147 (a)
148 (d)
149 (b)
150 (d)
151 (a)
152 (d)
153 (b)
154 (b)
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155 (d)
156 (a)
157 (d)
158 (a)
159 (c)
160 (c)
161 (c)
162 (a)
163 (c)
164 (c)
165 (c)
166 (a)
167 (c)
168 (a)
169 (b)
170 (c)
171 (d)
172 (c)
173 (b)
174 (d)
175 (b)
176 (a)
177 (d)
178 (b)
179 (c)
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Answers & Explanations
9 (d) High yielding potential under the climatic conditions
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process semen from chosen male is injected into
reproductive tract of chosen females. By this desirable
matings are performed.
(a) MOET stands for Multiple Ovulation Embryo
Transfer technology. It is the programme for herd
improvement in animals like cattles, sheeps, rabbits,
buffaloes, mares, etc.
(a) In MOET, the selected cow is administered with a
hormone having follicle stimulating hormone like activity
to induce follicular maturation and superovulation. Due
to this instead of one egg, which they normally yield per
cycle, they produce 6-8 eggs.
(d) During MOET fertilised eggs at 8-32 cells stages,
are recovered non-surgically and transferred to
surrogate mothers. The genetic mother is available for
another round of superovulation. This technology has
been demonstrated for cattle, sheep, rabbits, buffaloes,
mares, etc.
(d) Keeping beehives in crop fields during flowering
period increases pollination efficiency and improves the
total yield, which is beneficial in terms of crop yield
and honey yield.
(a) Fisheries is an industry devoted to the catching,
processing or selling of fish, shell fish (prawns and
molluscs) or other aquatic animals such as crabs,
lobster, edible oyster, etc.
(b) Pisciculture and aquaculture has contributed towards
increased production of aquatic organisms. Aquaculture
involves production of useful aquatic plants and animals
such as fishes, prawns, shrimps, lobsters, crabs,
molluscs (edible and pearl oysters) by proper utilisation
of small and large bodies of water. The production of
fishes is called pisciculture. It involves proper
utilisation of fresh water, brackish water and coastal
areas. Quick growing fishes are selected for this
purpose.
(a) The by products of fisheries are as follows
Isinglass – Gelatinous substance obtained from the
air bladder of perches and salmons used for
clarification of wine and beer.
Fishoil – It is extracted from the liver of sharks, etc.,
and has medicinal value.
Manure or fishmeal – It is obtained from non-edible
(waste) part of fishes, i.e. fins and tails. It is a good
source of protein and given to poultry as food.
Shagreen – It is the skin of sharks and rays having
pointed scales used in polishing wood and other
materials.
(d) During the mid 1960s, Green revolution in India was
witnessed, i.e. a rapid increase in the production of
agricultural products (particularly wheat). It was
possible due to the introduction of high yielding
varieties, increased irrigation facilities, application of
fertilisers and pesticides, multiple cropping and better
agricultural management.
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Answers & Explanations
13
of that area and resistance to diseases are two most
important quality to be considered while selection of
good breeds.
(a) Bird flu is a viral disease affecting poultry birds. It
resembles influenza and caused by a virus H5 N1 .
(a) The improved breeds shown in the diagram are
Jersey (A) and Leghorn (B). Jersey is an exotic cattle
breed from Island of Jersey in english channel. Leghorn
is a Mediterranean breed of chicken. Other options like
Sangamneri, jamunapari and sirohi are breeds of goat.
Marwari is a horse breed and beetal is a type of insect.
(a) Anthrax is an infectious bacterial disease found in
cattle, buffaloes, sheeps and goats. Other options like
tick fever is a protozoan poultry disease. Necrosis is a
form of premature cell death. Rinderpest is an infectious
disease of cattle caused by virus.
(b) The term ‘breed’ refers to a group of animals related
by descent and similar in most characters like general
appearance, features, size, configuration, etc.
(a) Inbreeding refers to the mating of more closely
related individuals within the same breed for 4-6
generations. The breeding strategy is as
follows–superior males and superior females of the
same breed are identified and mated in pairs. The
progeny obtained from such matings are evaluated and
superior males and females among them are identified
for further mating.
(a) When closely related animals of same breed are
crossed continuously for few successive generations, it
results in increase of homozygosity. Thus, homozygous
purelines in cattles can be obtained by this method.
(c) Outbreeding is an important strategy of animal
husbandry because it is useful in overcoming inbreeding
depression. It is the breeding of stocks or individual
animals that are not closely related with each other.
Inbreeding depression is the condition in which the
fertility and the productivity of animals is reduced due
to the continuous inbreeding in same species. Thus,
outbreeding helps to restore the fertility and yield.
(a) Outbreeding refers to the mating of unrelated
animals belonging to
Individuals of the same breed but having no common
ancestors on either side for at least
4-6 generations (outcrossing).
Individuals of the different breeds (cross-breeding).
Individuals of different species (interspecific
hybridisation).
(b) The interspecific hybridisation is the mating or cross
between male and female animals of two different
related species belonging to same genus. This combines
the desirable features.
(b) Controlled breeding experiments are carried out
using artificial insemination (and MOET). In this
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45 (d) Green revolution was dependent mainly on plant
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breeding techniques for development of high yielding
and disease resistant varieties of wheat, rice and maize.
This was all done by the efforts of Prof. MS
Swaminathan who is also called as the father of green
revolution in India.
(a) Genetic variability is the root of any breeding
programme. Pre-existing genetic variability is collected
from wild varieties, species and relatives of the
cultivated crop species and preserved for later
evaluation.
(a) The main aim of germplasm evaluation in plant
breeding programme is to identify the plants with
desirable combination of characters.
The identified plants are then propagated and used in
the process of hybridisation to create improved progeny
or purelines.
(b) The sugarcane, Saccharum barberi was originally
grown in North India, but had poor sugar content and
yield.
(b) Tropical cane grown in South India is Saccharum
officinarum had thicker stems and higher sugar content.
Both varieties of sugar cane, i.e. Saccharum barberi and
Saccharum officinarum were suceessfully crossed to get
sugar cane varieties combining the desirable qualities of
high yield, thick stem, high sugar and ability to grow in
the sugar cane areas of North India.
(c) Black rot of crucifer is a bacterial disease. Tobacco
mosaic and turnip mosaic are viral diseases and late
blight of potato is caused by fungi.
(b) Hairy root disease of dicot plants is caused by
Agrobacterium rhizogene. Agrobacterium
tumefaciens causes stem gall of coriander.
Bacillus thuringiensis is soil dwelling Gram positive
bacterium, now being using as pesticide against cotton
stem borer insect.
Meloidgyne incognita causes root knot disease in
tomato and brinjal.
(d) Plant breeding is carried out by the conventional
breeding techniques or by mutation breeding. The
conventional method of breeding for disease resistance
is that of hybridisation and selection. Mutation breeding
is defined as the process of breeding by artificially
inducing mutations using chemicals (like aniline) or
radiations like (gamma radiation).
(d) The conventional method of breeding for disease
resistance includes screening of germplasm for resistant
sources and hybridisation of selected parents. Whereas,
induction of mutation is done under mutation breeding
technique.
(c) Intergeneric crosses are made between plants
belonging to different genera of the same family. The
hybrids produced by this method are both scientifically as
well as agronomically significant. For example, Triticale
the first man made cereal crop is an allopolyploid, which
was produced by intergenic hybridisation between wheat
(Triticale) and rye (Secale).
72 (d) All measures can be taken to cultivate disease free
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chickpea crop. Bacterial blight of chickpea is caused by
bacterium Xanthomonas campestris. The stem and the
leaves of infected plant give blighted or burnt up
appearance. Control measures include roguing 3-years
crop rotation, disease-free seeds, spray of copper
fungicides (bordeaux mixture) and use antibiotics
besides sowing disease resistant varieties.
(d) Mutation is the process by which genetic variations
are created through changes in the base sequence within
genes. It results in the creation of a new character or
trait not found in the parental type.
(d) Mutations to create a new character or trait can be
artificially induced through the use of chemicals (like
hydrazine, methyl methane sulphonate, etc.) or
radiations (like X-rays, UV-rays and γ-rays, etc). These
agents are called as mutagens.
(a) Hairy leaves of many plants are associated with
resistance to insect pests. For example, resistance to
jassids in cotton and cereal leaf beetle in wheat.
(d) All options are not the disease resistant varieties.
These all are insect pest resistant varieties. Pusa Gaurav
is the variety of Brassica which resistant to aphids, Pusa
Sem-2 is the variety of flat bean and resistant to jassids,
aphids and fruit borer, while Pusa Sawani is the variety
of okra which is resistant to shoot and fruit borers.
(a) Hidden hunger is indicated as the lack of protein,
vitamins and micronutrients deficiencies in the food.
This is because not all people can afford to buy
adequate vegetable, fruits, legumes, fish and meat.
Thus, more than 840 million people in the world
suffering from hidden hunger.
(d) Majority of people suffer from hidden hunger or
malnutrition because their food does not contain
essential micronutrients particularly iron, iodine, zinc
and vitamin-A.
(d) Biofortified crops are the crops with high nutritive
value. These crops have high levels of vitamins and
minerals or higher proteins and healthier fats. They are
developed by the process of biofortification.
(a) Atlas 66 is a biofortified wheat crop having high
amount of amino acid and protein content.
(a) One of the alternate sources of protein for animal
and human nutrition is single cell protein. It is the
production of edible proteins on a large scale by
cultivation of microorganisms.
(c) Single cell proteins are formed from certain
beneficial microorganisms like
— Methylophilus methylotrophus
Bacteria
Cyanobacteria
— Spirulina.
(d) Microbes are being grown on an industrial scale as
source of good protein. Blue-green algae like Spirulina
can be grown easily on materials like waste water from
potato processing plants (containing starch), straw,
molasses, animal manure and even sewage, to produce
large quantities and can serve as food rich in protein,
minerals, fats carbohydrate and vitamins.
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use substrates like sewage, animal manure, etc., which
cause pollution. Therefore, by utilisation of such kind of
substrates in the production of SCP helps in reduction
of environmental pollution.
(b) 250 g of microorganism like Methylophilus
methylotrophus, because of its high rate of biomass
production and growth, can be expected to produce
25 tonnes of protein.
(a) Explant is used in plant tissue culture. It is an
excised plant part which has the potential to give rise to
whole new plant, e.g. leaves, shoot, roots, nodes, etc.
The plants obtained through this techniques are
morphologically and genetically similar to each other
and to their parents plant.
(c) Cellular totipotency is the ability of a explant to give
rise to a complete plant, when cultured in a suitable
culture medium at appropriate temperature and aeration
conditions.
(d) The requirements of tissue culture are growth
hormones (auxin, cytokinin), agar-agar, inorganic salts,
vitamins, amino acids, carbon source like sucrose, etc.
In plants tissue culture, the medium on which explants
are cultured is known as nutrient or culture medium. It
acts as a source of important nutrient required for
proper development of explant.
(b) Somatic embryogenesis is a technique of
micropropagation. It is the growing of plants from
meristematic tissue of somatic cells of plants on suitable
nutrient media under controlled conditions.
(a) Somaclones are plants produced from tissue culture
which are genetically identical to the original plant from
which they are grown. Somaclones are produced by
micropropagation technique of tissue culture.
(a) Virus free plants can be formed by meristem cutlure.
The reason behind this is that virus cannot propagate in
rapidly dividing cells, so meristematic zones of plant
always remain virus free.
For other options,
Protoplast fusion technique is used for making
somatic hybrids.
Somatic cell culture technique is used to propagate
plants from somatic cells using nutrient medium and
combination of hormones.
Callus culture is undifferentiated mass of tissue.
Growing callus from plant organs is called callus
culture.
(a) In floriculture, the practice of meristem culture is
used. Floriculture refers to large scale production of
flowers for economic purposes. Other options like
aquaculture and pisciculture are related to fisheries.
(c) In virus infected plant, both apical and axillary
meristems are free of virus and use for the healthy plant
cultivation because of rapid cell divisions and strong
interferon activity in this region. These tissues form a
protective impermeable covering around themselves,
which is non-penetrable by any pathogen. Hence, these
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tissues are used in the production of diseased free plants
by tissue culture.
(d) A protoplast is a cell without cell wall . It is a cell
that had its cell wall completely or partially removed
using either mechanical or enzymatic means.
(a) Somatic hybrids are produced by the fusion of
protoplasts of two cells, each having a desirable
character.
(b) Pomato is a somatic hybrid obtained by a mating
between potato and tomato whereas bomato is a somatic
hybrid between brinjal and tomato.
(c) Assertion is true, but Reason is false. Reason can be
corrected as
Bird flu is a disease of poultry caused by a virus H5 N1 .
The virus enters the human body through contact with
sick birds or their products.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
In tissue culture, somatic embryos or embryoids are
non-zygotic embryo like structures that develop in vitro
cultures from somatic cells of any type of tissue.
Here ‘totipotency’ property of plants cells is used, which
allow whole plant to be produced from any one plant cell.
(c) Assertion is true, but Reason is false. Reason can be
corrected as
In interspecific crosses, male and female animals of the
different related species are mated. The resultant
progeny may combine desirable features of both the
parents are infertile. Thus, are rare in nature.
The same applies to intergeneric crosses. It is the
crossing of two different animals/plants of different
genus. It is almost unknown in nature as the gametes
show species specificity.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Protoplast culture is an important technique of tissue
culture and this technique results in the production of
somatic hybrid plants.
(c) Assertion is true, but Reason is false. Reason can be
corrected as
Virus-free plants can be produced from the virus
infected plants by means of meristem tissue culture. In a
diseased plant, both the apical and axillary meristems
are free of virus.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Inbreeding is breeding between animals of the same
breed for 4-6 generations. Continued inbreeding causes
homozygosity which produces purelines.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Heterosis (Hybrid vigour) is the phenotypic superiority
of the hybrid over both of its parents in one or more
traits. In other words, when two unrelated individuals or
lines are crossed, the performance of F1 hybrid is often
superior to both its parents.
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CHAPTER 09 > Strategies for Enhancement in Food Production
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119 (a) Both Assertion and Reason are true and Reason is
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the correct explanation of Assertion.
Biofortification is breeding of crops with higher levels
of vitamins and minerals or higher protein and
healthier fats.
This increase nutrient value of crops. Since billions of
people in the world suffer from nutrient deficiencies or
hidden hunger. Biofortification of crops is the most
practical approach to improve the health of these
people.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
Aquaculture is the breeding, rearing, harvesting and
management of economically useful aquatic organisms
like fishes, shellfish, molluscs, crustaceans and other
aquatic plants. It is done to procure food and other
commercial products, restore habitats and replenish the
depleted stocks, etc.
(a) Both Assertion and Reason are correct and Reason
is the correct explanation of Assertion.
Light is an essential component of poultry farm
management because it determines the quantity of egg
production. An exposure to 14-16 hours of light period
during daytime ensures optimum production of eggs.
(b) Statement in option (b) is incorrect. It can be
corrected as
Inbreeding does not select harmful recessive genes. It
exposes harmful recessive genes that reduce fertility
and productivity and these are eliminated by selection.
Statement in other options are correct.
(d) Statement in option (d) is incorrect. It can be
corrected as
Inbreeding depression can be overcome by
outcrossing. In this method, mating of animals within
the same breed, but no common ancestor for 4-6
generations.
Statements in other options are correct.
(a) Statement in option (a) is incorrect about
inbreeding. It can be corrected as
Inbreeding depression decreases the productivity.
Continued inbreeding, usually reduces fertility of
animals and even their productivity. This condition is
called as inbreeding depression.
(a) Only statement in option (a) is correct, while other
are incorrect. These can be corrected as
Mating of individuals from entirely different breed is
called cross-breeding. It is the method of breeding
superior male of one breed with superior female of
another breed in order to combine the desirable
qualities of two different breeds in the progeny.
(d) Statements in option (a), (b) and (c) are correct, but
(d) is incorrect. It can be corrected as
Animal breeding involves crosses between useful
animal breeds aiming to increase the yield of animals
and to improve the desirable qualities of the product. It
has no concern with the development of resistance
against diseases.
128 (c) Only statement in option (c) is correct, while the other
statements are incorrect and can be corrected as
Hilsa, sardines, mackerel are marine fishes.
Catla and common carp are freshwater fishes.
Only the term pisciculture is used for rearing fishes
only.
(c) Only statement in option (c) is correct. Rest other
statements are incorrect. These can be corrected as
Pusa Gaurav is variety of Brassica, resistant to aphids.
Pusa A-4 is okra variety resistant to shoot and fruit
borer.
Parbhani kranti is resistant to yellow mosaic virus.
(c) Statements in option (a) and (b) are correct for Altas
66. It is a soft wheat that has been used since 1953 as a
genetic source of higher protein in wheat. It has been
used as a donor for cultivated wheat.
Statement in option (d) is incorrect. The correct form of
this statement is
Protina, Shakti and Rattan are three lysine rich maize
hybrids developed in India.
(a) Statements I and II are correct for animal husbandry.
Statement III is incorrect and can be corrected as
Animal husbandry does not deal with breeding plants for
human use. It is a component of plant breeding
programmes.
(d) Out of the given statements I and II are correct, while
III and IV are incorrect. The correct form of these
statements is
Common button mushrooms are a very rich source of
vitamin-B
A rice variety has been developed, by IARI which is
rich in iron.
(b) Option (b) represents the correct answer.
Inbreeding involves
Identification of superior males and superior females
of the same breed.
Mating of the superior animals.
Progeny obtained from such mating are evaluated and
assessed for the desirable traits.
It should be kept in mind that a superior cow or
buffalo is that which gives more milk per lactation.
Similarly, a superior bull is that which gives rise to
superior progeny as compared to those of other bulls.
This process of mating of superior progenies is
continued for 4-6 generations.
(b) Only statement II is incorrect, while the rest are
correct. The incorrect statement can be corrected as
Bee-keeping is not a labour-intensive method.
(a) Statements I and II are correct, while III and IV are
incorrect. The correct form of these statement are
Outbreeding is the breeding between the animals of
the same breed but no common ancestors or different
breeds or different species.
Crosses between the same breeds are called
inbreeding.
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CHAPTER 09 > Strategies for Enhancement in Food Production
142 (c) Only statement IV is incorrect. The correct form of
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breeding. Use of radiations is not involved in other three
options.
(c) Biofortification is the scientific process by which
crop plants are enriched with higher levels of vitamins
and minerals or higher protein and healthier fats.
It is the most practical means to improve public health.
(a) The capacity of a cell or an explant to grow and
develop into a whole plant is called ‘totipotency’.
(c) Any part of a plant used in tissue culture, which is
taken out and grown in a test tube under sterile
conditions in a special nutrient media is called an
explant. A whole plant can be generated from an
explant.
(a) The biggest constraint of plant breeding (conventional)
is the availability of limited number of disease resistance
genes that are present and identified in various crop
varieties or wild relatives.
(b) Micropropagation is propagation of plants in vitro to
achieve a large number of plants in very short duration.
This results in the production of genetically identical
plants and is widely used in forestry and floriculture.
(c) A protoplast is a plant, bacterial or fungal cell whose
cell wall is completely or partially removed using either
mechanical or enzymatic means.
(c) Both option (a) and (b) are correct. As the cell wall
of plant cells consists of pectin and cellulose which can
be removed by digestion with combination of enzymes
pectinase and cellulase to isolate the protoplast.
(b) Hilsa, sardines, mackerel and pomfrets are some of
the marine fishes.Catla, rohu and common carp are
freshwater fishes.
(a) Germplasm collection is the entire collection of
plants/seeds having all the diverse alleles for all genes
in a given crop.
(d) Statements II and III are correct, while I and IV are
incorrect and can be corrected as
Protoplasts from two different varieties of plants are
fused in the somatic hybridisation.
The hybrid protoplast contains characters of both
parental protoplast.
(c) Beeswax is the most common product of apiculture
which finds many uses in industry, cosmetics and
polishes of various kinds.
Honey is a food of high nutritive value and also finds
use in the indigenous systems of medicine. Royal jelly,
is the queenbees extraordinary source of food. It is rich
in nutrition values and is believed to be a potent
antioxidant. Prop oil is not a product of apiculture.
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Answers & Explanations
144
this statement is
Germplasm collection is the entire collection of plants
or seeds having all the diverse alleles for all genes in a
given crop.
Rest other statements are correct.
(c) Statements I, II and IV represent the advantages of
tissue culture/micropropagation, while statement III is
incorrect and can be corrected as
Genetically, similar plants can be produced by the
method of tissue culture.
(d) The chances of contacting bird flu from a properly
cooked (above 100°C) chicken and egg are negligible.
Highly pathogenic strains of avian influenza can be
found inside and on the surface of eggs. In an infected
bird, it may spread to all the parts including the meat.
However, proper cooking at or above 70°C, prior to
eating, will inactivate the virus in the egg as well as in
the meat.
(a) A group of animals that are related by descent and
are similar in most characters like general appearance,
features, size, configuration, etc., are said to belong to a
breed.
(d) Inbreeding increases homozygosity, i.e. state of
possessing two identical alleles, one inherited from each
parent. It is necessary if we want to evolve a pureline in
any animal.
(a) Sonalika and Kalyan Sona are outstanding semi
dwarf varieties of wheat possessing good yield potential
and disease resistant. These were developed in 1963.
(c) Black rot of crucifers is not a fungal disease. It is
caused by a bacteria, Xanthomonas campestris. Other
three diseases are caused by fungal pathogens.
(c) Several South Indian states raise 2-3 crops of rice
annually. The agronomic feature that makes this
possible is early yielding rice variety. These varieties
are a group of crops created intentionally during the
green revolution to increase global food production.
(a) In the sugarcane crop, a sugarcane farmer looks for
a combination of thick stem, long internodes, high sugar
content and disease resistance. In practice, Saccharum
barberi and Saccharum officinarum are being crossed to
develop such a combination.
(c) It is possible to induce mutations artificially in crop
plants through the use of chemicals or radiations (like
gamma radiations), and then selecting and using those
plants that have the desirable character as a source of
further breeding. This process is called mutation
241
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CHAPTER > 10
Microbes in
Human Welfare
NEET
KEY NOTES
Å
Microbes are microscopic, single-celled, minute organisms
that individually are too small to be seen with naked eyes,
i.e. can be seen only under a microscope.
Å
Microbes constitute major groups of biological systems on
the earth, which are present almost everywhere, i.e. in soil,
air, water, on/in plants and animals and also even inside our
body. These can be found in extreme conditions of pH
(alkaline and acidic soil) and temperature (thermal vents or
geysers and below the several metre thick snow layers).
Å
Å
Microbes are diverse group of organisms including
protozoans, bacteria, fungi, microscopic plants, viruses,
viroids and prions (proteinaceous infectious agents), etc.
Some microbes cause infections and diseases in human
beings, animals and plants. But several microbes are useful
to man in diverse ways.
Microbes in Household Products
Å
Å
We use microbes and microbe derived products almost
everyday. Curd is made by Lactobacillus and other bacteria
commonly called Lactic Acid Bacteria (LAB), which grow in
milk and convert it to curd.
A small amount of curd added to the fresh milk as inoculum
or starter contains millions of LAB, which at suitable
temperature multiply and produce acids that coagulate and
partially digest the milk proteins. It also increases the
content of vitamin-B12 in curd making it more nutritious and
helps in replacing disease causing microbes in the stomach.
Å
The dough used for making foods such as dosa, idli, cakes
and bread is fermented by using baker’s yeast (Saccharomyces
cerevisiae). The puffed up appearance of dough is due to the
production of CO 2 .
Å
A traditional drink of Southern India called ‘toddy’ is also
made by fermenting sap from palms.
Å
Cheese of different textures, flavours, etc., are also made by
using different microbes, e.g. the holes in ‘Swiss cheese’ are
due to the production of a large amount of CO 2 by a
bacterium called ‘Propionibacterium shermanii’.
Å
The ‘Roquefort cheese’ is ripened by growing a specific
fungi (Penicillium roqueforti) on them, which gives them a
particular flavour.
Microbes in Industrial Products
In industry, microbes are used to make a number of products
such as beverages, enzymes and antibiotics, etc., valuable to
human beings. Industrial scale production requires growing
microbes in very large vessels called fermentors.
Fermented Beverages
Å
Large scale production of beer, brandy, whisky, rum, etc., is
done by fermenting malted cereals and fruit juices using
unicellular fungi Saccharomyces cerevisiae (brewer’s yeast).
Å
Different types of alcoholic drink like wine and beer are
produced without distillation. Whisky, brandy and rum are
produced by distillation of the fermented broth.
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CHAPTER 10 > Microbes in Human Welfare
disposed, in water bodies, it needs to be treated in
Sewage Treatment Plants (STPs) to make it less
polluting.
Antibiotics
Å
Å
These are the chemical substances which are produced by
some microbes to kill or retard the growth of other disease
causing microbes. Penicillin was the first antibiotic to be
discovered by Alexander Fleming.
Alexander Fleming had observed that if a mould of
Penicillium notatum grows on a nutrient medium, it does not
let a bacterium Staphylococcus grow around it. He isolated the
chemical produced by the mould and named it penicillin.
However, its full potential as an effective antibiotic was
established later on by Ernst Chain and Howard Florey. For
this discovery, Fleming, Chain and Florey were awarded the
Nobel Prize in 1945.
Å
Antibiotics are widely used in treating human and animal
bacterial diseases. Deadly diseases like plague, whooping
cough (kali khansi), diphtheria, leprosy (kusht rog) are
completely curable diseases now due to the use of antibiotics.
Å
One of the most productive sources of antibiotics has been
the genus–Streptomyces from which many antibiotics have
been derived. Some of them are streptomycin, tetracycline,
erythromycin, terramycin, which are obtained from
Streptomyces griseus, S. aureofaciens, S. erethreus and
S. remosus, respectively.
Chemicals, Enzymes and Other
Bioactive Molecules
Å
Yeast (Saccharomyces cerevisiae) is used for the commercial
production of ethanol.
Å
Microbes are also used for the production of enzymes.
Lipases are used in detergent formulations to remove oily
stains from laundry. Pectinases and proteases are used to
clarify bottled juices. Streptokinase produced from
Streptococcus (a bacterium) is used as a ‘clot buster’ for
removing blood clots from blood vessels of patients.
In organ transplant patients, a bioactive molecule
cyclosporin-A acts as an immunosuppressant and is
produced by Trichoderma polysporum (fungi) and statins act as
blood cholesterol lowering agent and are obtained from the
yeast, Monascus purpureus.
Microbes in Sewage Treatment
Å
Certain heterotrophic microbes naturally present in
sewage are used in its treatment. This treatment is
carried out in two stages, i.e. primary treatment and
secondary treatment.
Å
In primary treatment, physical removal of particles, i.e.
large and small, is done from the sewage through
filtration and sedimentation. All solids that settle down,
form the primary sludge and the supernatant forms the
effluent, which is taken for secondary treatment.
Å
In secondary treatment or biological treatment, the
primary effluent is passed into large aeration tanks
where it is constantly agitated mechanically. This
allows the growth of the aerobic microbes into flocs
(masses of bacteria associated with fungal filaments to
form mesh-like structures) which consume the major
part of the organic matter in the effluent that
significantly reduces the BOD (Biochemical Oxygen
Demand) of the effluent.
Å
BOD is the amount of oxygen that would be consumed,
if all the organic matter in one litre of water were
oxidised by bacteria. The sewage water is treated till the
BOD is reduced. The greater is the BOD of wastewater,
more is its polluting potential.
Å
The effluent is then passed into a settling tank where
the bacterial flocs are allowed to sediment. This
sediment is called activated sludge as it contains active
microbes. From here
Many fungi and bacteria are used for commercial production
of organic acids like citric acid produced by Aspergillus niger
(a fungus), acetic acid produced by Acetobacter aceti
(a bacterium), butyric acid produced by Clostridium butylicum
(a bacterium) and lactic acid produced by Lactobacillus
(a bacterium).
Å
Å
Å
Sewage is the municipal wastewater generated everyday in
cities and towns. It contains large amounts of organic matter
and many pathogenic microbes. That is why before being
n
n
n
A small part of the activated sludge is pumped back
into the aeration tank to serve as the inoculum.
The remaining major part of the sludge is pumped
into large tanks called anaerobic sludge digesters.
Here, lack of oxygen kills the aerobic bacteria which
are digested along with the other biomass by
anaerobic bacteria and fungi.
The effluent from the secondary treatment plant is
generally released into natural water bodies like
rivers and streams.
Å
During digestion of organic matter, bacteria produce a
mixture of gases such as methane, hydrogen sulphide
and carbon dioxide. These gases form biogas, which is
inflammable and can be used as a fuel.
Å
The ministry of environment and forests has initiated
the Ganga Action Plan and Yamuna Action Plan to
save these major rivers of our country from pollution.
These plans propose to build a large number of sewage
treatment plants, so that only treated sewage may be
discharged into the rivers.
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KEY NOTES
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244
Microbes in Production of
Biogas
Å
Biogas is a mixture of gases (mainly CH 4 , CO 2 , H 2 )
produced by certain bacteria, which grow anaerobically on
cellulosic material. These bacteria are collectively called
methanogens and are found in the anaerobic sludge
generated during sewage treatment and in the rumen (a
part of stomach) of cattle, helping in the breakdown of
cellulose. It plays an important role in the nutrition of
cattle. Thus, the excreta (dung) of cattle, commonly called
gobar (which is rich in methanogenic bacteria) can be used
for generation of biogas, commonly called as gobar gas.
Å
Biogas plant consists of a concrete tank (10-15 feet deep) in
which bio-wastes are collected and slurry of dung is fed.
Methanobacterium in the dung acts on the biowaste to
produce biogas (used for cooking and lighting).
Å
The biogas plant has an outlet, which is connected to a
pipe to supply biogas to nearby houses. Spent slurry
removed from plant can be used as fertiliser.
Å
Biogas production technology was developed in India
mainly by IARI (Indian Agricultural Research Institute)
and KVIC (Khadi and Village Industries Commission).
Microbes as Biocontrol Agents
Å
Biocontrol refers to the use of biological methods for
controlling various plant diseases and pests.
Å
This method is employed because the long time use of
chemical insecticides, pesticides and weedicides has been
proved to be harmful for all living organisms and the
environment (air, water, soil, etc).
Å
Biological control of pests and diseases The use of
biocontrol measures has become more preferable since it
greatly reduces our dependence on toxic chemicals. Here,
pests can be controlled by making use of natural predation
rather than chemicals.
by the insect larvae. In the gut of the larvae, the toxin is
released and the larvae get killed. This will kill the
caterpillars, but leave other insects unharmed.
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Å
Biocontrol involves creation of a system where
the insects/pests are not eradicated rather are
kept at manageable levels by a system of check and
balances within ecosystem. Various microbes can be
used as biocontrol agents, e.g.
Aphids and mosquitoes can be controlled by ladybird
beetle and dragonflies, respectively.
Butterfly caterpillars can be killed by using the bacteria
Bacillus thuringiensis. Bt is available as dried spores
which are mixed with water and sprayed on to plants
such as brassicas and fruit trees, where these are eaten
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NEET
Viruses (like baculoviruses belonging to genus
Nucleopolyhedrovirus) are excellent for species specific,
narrow spectrum insectivides. These do not have
negative impact on non-target insects and have narrow
spectrum insecticidal applications.
Integrated Pest Management (IPM) is an environmentally
sensitive and effective approach of pest management that
uses information on life cycles of organisms and their
interaction with environment. The integrated pest
management is done to control insects and pests of plants,
animals and humans.
Microbes as Biofertilisers
Å
To cut down the pollution caused by chemical fertilisers, it
is important to switch to organic farming (raising crops
through the use of components of biological origin, e.g.
biofertilisers).
Å
Biofertilisers are organisms, e.g. bacteria, fungi and
cyanobacteria that enrich the nutrient quality of the soil.
Å
The main sources of biofertilisers are as follows
n
Å
Fungi (like Trichoderma sp., a free-living fungi, that are
common in root ecosystems) are effective against
several fungal plant pathogens.
n
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Bacteria Rhizobium is a symbiotic bacterium living in
the root nodules of legumes and fixes atmospheric
nitrogen into organic compounds. Azotobacter and
Azospirillum are free-living bacteria, which fix
atmospheric nitrogen from the air and thus, enrich the
nitrogen content of the soil.
Fungi form symbiotic association with plants
(mycorrhiza), which absorb phosphorus from the soil
and pass it on to the plants. Many members of genus
Glomus form mycorrhiza. Plants with mycorrhizal
association show other benefits also, such as
Resistance to root borne pathogens.
Tolerance to salinity and drought.
Increase in plant growth and development.
Cyanobacteria are autotrophic microbes found in
aquatic and terrestrial environments. Many of them
fix-nitrogen, e.g. Anabaena, Nostoc, Oscillatoria, etc.
In paddy fields, cyanobacteria serve as important
biofertiliser, it also adds organic matter to the soil, thus
increasing its fertility.
KEY NOTES
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245
Mastering NCERT
MULTIPLE CHOICE QUESTIONS
TOPIC 1
~ Basic Concepts and Microbes in
Household Products
1 Microorganisms or microbes are found in
(a)
(b)
(c)
(d)
soil, air, water and inside the bodies of living organisms
thermal vents deep in soil
under snow and in highly acidic environments
All of the above
2 The microscopic proteinaceous infectious agents are
(a) viroids
(c) protozoans
called
(a)
(b)
(c)
(d)
Citric Acid Bacteria (CAB)
Lactic Acid Bacteria (LAB)
Tartaric Acid Bacteria (TAB)
Formic Acid Bacteria (FAB)
7 The most abundant prokaryotes helpful to human in
(b) prions
(d) bacteria
3 The nutritive medium for growing bacteria and many
fungi in the laboratory is called
(a)
(b)
(c)
(d)
6 Microorganisms such as Lactobacillus are commonly
culture media
fermentation media
baking media
None of the above
making curd from milk and in the production of
antibiotics are the ones categorised as
(a) cyanobacteria
(b) archaebacteria
(c) chemosynthetic autotrophs
(d) heterotrophic bacteria
8 The starter or inoculum is added to the fresh milk in
4 Given below is the diagram of a bacteriophage. In
which one of the option, all the six parts A, B, C, D, E
and F are correct?
A
order to convert milk into curd and improves its
nutritional quality by increasing
(a) vitamin-B12
(c) calcium
formation from milk and select the correct option for
A and B.
Curd is added as inoculum to the fresh milk
C
LAB shows growth in milk
D
Production of ..... A ..... starts
Coagulation and digestion of milk protein
E
(a) A–Head, B–Tail, C–Collar, D–Pins, E–Plate, F–Prongs
(b) A–Head, B–Collar, C–Tail, D–Plate, E–Pins, F–Prongs
(c) A–Head, B–Tail, C–Collar, D–Plate, E–Prongs, F–Pins
(d) A–Head, B–Collar, C–Tail, D–Pins, E–Plate, F–Prongs
5 Which of the following bacteria convert milk into
curd?
(a)
(b)
(c)
(d)
(b) protein
(d) All of these
9 Study the following flowchart that shows curd
B
F
CBSE-AIPMT 2012
Propionibacterium shermanii
Saccharomyces cerevisiae
Lactobacillus
Thermophilic bacteria
Improved nutritional quality by increased ..... B .....
(a)
(b)
(c)
(d)
A–citric acid, B–vitamin-B12
A–lactic acid, B–vitamin-B12
A–lactic acid, B–vitamin-C
A–citric acid, B–vitamin-B 2
10 Which gas is released during the process of
fermentation that gives the puffy appearance to dough
for making bread?
(a) CO2
(c) O2
(b) CO
(d) H2
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246
11 Toddy, a traditional drink of Southern India is made by
13 Roquefort cheese is formed by ripening with ...A...for
...A... of sap from …B… tree. Here, A and B refer to
a particular flavour. Here A refers to
(a) A–fermentation, B–palm
(b) A–fermentation, B–bamboo
(c) A–distillation, B–palm
(d) A–distillation, B–bamboo
(a) yeast
(c) bacteria
14 Which of the following food items are produced
through fermentation by the microorganisms?
I. Idli
II. Dosa
IV. Cheese
III. Toddy
Choose the correct option.
12 Swiss cheese is formed by the bacterium
(a)
(b)
(c)
(d)
(b) fungi
(d) None of these
Aspergillus niger
Lactobacillus
Propionibacterium shemanii
Penicillium roqueforti
(a) I, II and III
(c) II, III and IV
(b) I, III and IV
(d) All of these
TOPIC 2 ~ Microbes in Industrial Products
15 Which one of the following equipments is
essentially required for growing microbes on a large
scale, for industrial production of enzymes?
NEET 2019
(a) Sludge digester
(c) Bioreactor
(b) Industrial oven
(d) BOD incubator
16 The alcoholic beverages produced by the
distillation of the fermented broth are
(a)
(b)
(c)
(d)
wine and beer
wine, whisky and brandy
whisky, brandy and rum
whisky, beer and brandy
used to treat American soldiers wounded in World
War-II?
(a) Streptokinase
(c) Statins
production of beverages like wine, beer, whisky
brandy or rum?
22 Who got Nobel Prize in 1945 for the discovery of
penicillin as an antibiotic?
(a) Alexander Fleming
(c) Howard Florey
Clostridium butylicum
Aspergillus niger
Saccharomyces cerevisiae
Penicillium notatum
(a)
(b)
(c)
(d)
diphtheria, whooping cough
plague
leprosy
All of the above
following table and select the correct answer.
Types of microbes Scientific names
Bacterium
CBSE-AIPMT 2012
(a) citric acid and lactic acid
(b) lipase and pectinase
(c) bread and beer
(d) cheese and butter
19 Brewer’s yeast is
Penicillium notatum
Trichoderma polysporum
Propionibacterium shermanii
Saccharomyces cerevisiae
20 Who observed a mould growing in unwashed
culture plate while working on Staphylococcus
bacterium?
(a) Ernst Chain
(c) Lamarck
(b) Ernst Chain
(d) All of these
24 Identify the blank spaces A, B, C and D given in the
18 Yeast is used in the production of
(a)
(b)
(c)
(d)
(b) Penicillin
(d) Neomycin
23 Antibiotics are used to treat diseases like
17 Which of the following organisms is used in the
(a)
(b)
(c)
(d)
21 Which one of the following antibiotics was extensively
(b) Alexander Fleming
(d) Florey
A
Commercial
products
Lactic acid
Fungus
B
Citric acid
C
Acetobacter aceti
Acetic acid
Fungus
Penicillium notatum
D
(a) A–Lactobacillus, B–Aspergillus niger, C–Bacterium,
D–Penicillin
(b) A–Staphylococcus, B–Clostridium, C–Yeast, D–Penicillin
(c) A–Lactobacillus, B–Microsporum, C–Yeast, D–Penicillin
(d) A–Staphylococcus, B–Microsporum, C–Agaricus,
D–Penicillin
25 Which one of these microbes is used in the commercial
production of butyric acid?
(a)
(b)
(c)
(d)
Clostridium butylicum
Streptococcus butylicum
Trichoderma polysporum
Saccharomyces cerevisiae
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CHAPTER 10 > Microbes in Human Welfare
26 Which of the following is correctly matched for the
product produced by them?
(a)
(b)
(c)
(d)
NEET 2019
Acetobacter aceti – Antibiotics
Methanobacterium – Lactic acid
Penicillium notatum – Acetic acid
Saccharomyces cerevisiae – Ethanol
27 Choose the incorrect pair.
247
30 Monascus purpureus is a yeast used commercially in
the production of
31 Which of the following is a commercial blood
(a) Lipases – Used in detergents for removing oil stains
(b) Pectinases and proteases – Used in clarifying
bottled juices
(c) Statins – Competitively inhibit the enzyme
responsible for cholesterol synthesis
(d) None of the above
28 Which of the following is used as ‘clot buster’ for
cholesterol lowering agent?
(a)
(b)
(c)
(d)
(b) Statins
(d) Streptokinase
29 Identify the blank spaces A, B, C and D given in the
following table and select the correct answer.
Types of
microbes
Fungus
C
Scientific
names
A
Monascus
purpureus
Medical
Products
applications
Cyclosporin-A
B
Statin
D
(a) A–Trichoderma polysporum, B–As an
immunosuppressive agent in organ transplant patients,
C–Yeast, D–As blood-cholesterol lowering agent
(b) A–Trichoderma polysporum, B–As blood-cholesterol
lowering agent, C–Protozoa, D–As an
immunosuppressive agent in organ transplant patients
(c) A–Clostridium butylicum, B–Used as a clot-buster,
C–Yeast, D–As blood- cholesterol lowering agent
(d) A–Clostridium butylicum, B–As blood-cholesterol
lowering agent, C–Yeast, D–Used as a clot-buster
NEET 2019
Statin
Streptokinase
Lipases
Cyclosporin-A
32 Which of the following is incorrectly matched in the
given table?
removing clots from blood vessels of patient who
have undergone myocardial infarction?
(a) Ethanol
(c) Cyclosporin-A
CBSE-AIPMT 2012
(a) ethanol
(b) streptokinase for removing clots from the blood vessels
(c) citric acid
(d) blood cholesterol lowering agent, statins
Microbes
(a)
Monascus
purpureus
(b)
Streptococcus
(c)
Clostridium
butylicum
(d)
Trichoderma
polysporum
NEET 2016
Products
Statins
Applications
Lowering of blood
cholesterol
Streptokinase
Removal of clot from
blood vessel
Lipase
Removal of oil stains
Cyclosporin-A Immunosppressive drug
33 Which industrial products are synthesised from
microbes?
I. Antibiotics
II. Toddy
III. Bioactive molecules
IV. Bread
Choose the correct option.
(a)
(b)
(c)
(d)
I, II, III and IV
II, III and IV
I and IV
III and IV
TOPIC 3 ~ Microbes in Sewage Treatment
34 Sewage contains large amounts of …A… and …B… .
Here A and B refer to
(a)
(b)
(c)
(d)
A–inorganic matter, B–bacteria
A–organic matter, B–pathogenic microbes
A–organic matter, B–virus
A–inorganic matter, B–pathogenic microbes
35 Primary treatment of wastes is the
(a) physical removal of large and small particles from sewage
(b) biological removal of large and small particles from
sewage
(c) Both (a) and (b)
(d) chemical removal of large and small particles from
sewage
36 In the primary treatment of sewage, the floating
debris is removed by sequential ... by passing through
wire mesh screens. The most appropriate word for
filling the blank is
(a) filtration
(c) condensation
(b) sedimentation
(d) evaporation
37 In the primary treatment of sewage, the soil and small
pebbles are removed by
(a) filtration
(b) sedimentation
(c) condensation
(d) evaporation
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38 Which one of the following in sewage treatment
removes suspended solids?
(a) Tertiary treatment
(c) Primary treatment
NEET 2017
(b) Secondary treatment
(d) Sludge treatment
39 In the biological treatment of sewage, the masses of
bacteria held together by fungal filament to form
mesh-like structures called as
(a) activated sludge
(c) flocs
(b) aerobic process
(d) anaerobic sludge
40 Choose the correct option to fill in the blanks.
I. Primary treatment of sewage involves physical
removal of small and large particles through ...A... and
...B... .
II. Microbes consume the major part of organic matter in
the effluent and reduce ...C... of sewage.
III. ...D... particularly ...E... anaerobically breakdown
cellulosic material and produce CO2 and H2 from
anaerobic sludge during ...F... . treatment.
IV. When BOD of sewage has reduced, the effluent is
passed into ...G... . Here, A to G can be
(a) A–sedimentation, B–centrifugation, C–BOD,
D–Methanogen, E–Methanobacterium, F–water gas
plant, G–settling tank
(b) A–centrifugation, B–sedimentation, C–BOD,
D–Methanogen, E–Methanococcus, F–biogas plant,
G–sludge tank
(c) A–filtration, B–centrifugation, C–BOD,
D–Methanogen, E–Methanobacillus, F–gobar gas plant,
G–filtre tank
(d) A–filtration, B–sedimentation, C–BOD,
D–Methanogen, E–Methanobacterium, F–sewage
treatment plant, G–settling tank
41 In the sewage treatment, bacterial flocs are allowed to
sediment in a settling tank. This sediment is called as
(a) activated sludge
(c) anaerobic sludge
(b) primary sludge
(d) secondary sludge
42 Given below is the flowchart of sewage treatment.
Identify A, B, C, D and E and select the correct option.
Primary sludge
Primary
treatment
Effluent
from primary
settling tank
Secondary treatment
E
D
Sedimentation
C
43 Primary sludge
CBSE-AIPMT 2014
(a) possesses flocs of decomposer microbes
(b) requires aeration for formation
(c) involves little decomposition
(d) forms during secondary sewage treatment
44 During sewage treatment, biogas is produced, which
includes
NEET 2013
(a) methane, hydrogen sulphide and carbon dioxide
(b) methane, oxygen and hydrogen sulphide
(c) hydrogen sulphide, methane and sulphur dioxide
(d) hydrogen sulphide, nitrogen and methane
45 Microbes are used in
I. primary treatment of sewage.
II. secondary treatment of sewage.
III. anaerobic sludge digesters.
IV. production of biogas.
Choose the correct option.
(a)
(b)
(c)
(d)
I, II and III
I, III and IV
II, III and IV
All of the above
46 The BOD test measures the rate of uptake of oxygen
by microbes in water bodies. The greater BOD of
sample water, indicates that
(a) it is highly polluted
(b) it is not polluted
(c) it is moderately polluted
(d) pollution level cannot be determined
47 Which of the following plans has been initiated by the
A
B
Biogas
formation
(a) A–Small aeration tank, B–Microbial digestion, C–High
BOD, D–Activated sludge, E–Aerobic sludge digesters
(b) A–Large aeration tank, B–Mechanical agitation,
C–Increased BOD, D–Activated sludge, E–Aerobic
sludge digesters
(c) A–Small aeration tank, B–Microbial digestion, C–Low
BOD, D–Activated sludge, E–Anaerobic sludge
digesters
(d) A–Large aeration tank, B–Mechanical agitation,
C–Reduced BOD, D–Activated sludge, E–Anaerobic
sludge digesters
Flocs
Ministry of Environment and Forests to protect rivers
from water pollution?
(a)
(b)
(c)
(d)
Ganga action plan
Yamuna action plan
Both (a) and (b)
None of the above
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CHAPTER 10 > Microbes in Human Welfare
TOPIC 4 ~
Microbes in Production of Biogas
48 The most flammable gaseous component of biogas is
(a)
(b)
(c)
(d)
249
methane, CO2 , H2 and H2 S
methane
CO2 , H2 and H2 S
CO, methane and N2
(a)
(b)
(c)
(d)
A–Sludge, B–Dung + Water, C– Gas holder
A–Dung + Water, B–Sludge, C–CH4 + CO2
A–Sludge, B–Gas holder, C–Dung + Water
A–CH4 + CO2 , B–Dung + Water, C–Sludge
53 Study the following flowchart of biogas production
49 Methanogens are found in
I. organic acid
II. rumen of cattle
III. butanal
IV. anaerobic sludge
and select the correct option for A, B and C.
Stage III
C
B
Choose the correct option.
(a) I and II
(c) II and IV
(b) II and III
(d) III and IV
Organic acids
Stage II
A
50 Which of the following bacteria is present in the
rumen of cattle?
(a) Rhizobium
(c) Methanobacterium
production of biogas from the dung of ruminant
NEET 2016
animals, include the
(b) methanogens
(d) halophiles
52 The diagram given below represents a typical biogas
plant. Select the correct option for A, B and C,
respectively.
Gas
C
A
Digester
(b) biopesticide
(d) bioweapon
56 In Bt cotton, the Bt toxin present in plant tissue as
protoxin is converted into active toxin due to
(a)
(b)
(c)
(d)
Fats
Cellulose
Hemicellulose
(a) A–Methanogenic bacteria, B–Fermentative microbes,
C–CO2 and hydrogen (biogas)
(b) A–Anaerobic microorganisms, B–Methanococcus,
C–CO2 and nitrogen (biogas)
(c) A–Anaerobic microbes, B–Methanogenic bacteria,
C–CO2 and methane (biogas)
(d) A–Aerobic microorganism, B–Methanobacter, C–CO2
and methane (biogas)
54 Gobar gas generation technology in India was
(a) A–Rural Bank of India, B–Khadi and Village Industries
Commission
(b) A–Indian Agricultural Research Institute, B–Khadi and
Village Industries Commission
(c) A–National Bank for Agriculture and Development,
B–Indian Agricultural Research Institute
(d) A–National Bank for Agriculture and Development,
B–Khadi and Village Industries Commission
Microbes as Biocontrol Agents and Biofertilisers
55 Bacillus thuringiensis is used as
(a) biofungicide
(c) biocontrol agent
Proteins
developed by the collaboration of ...A... and ...B... .
Here, A and B refer to
B
TOPIC 5 ~
Soluble compounds
or monomers
(b) Azotobacter
(d) Clostridium
51 The primitive prokaryotes responsible for the
(a) thermoacidophiles
(c) eubacteria
Stage I
alkaline pH of the insect gut
CBSE-AIPMT 2015
acidic pH of the insect gut
action of gut microorganisms
the presence of conversion factors in insect gut
57 Cultivation of Bt cotton has been much in the news.
The prefix Bt means
(a) ‘Barium-treated’ cotton seeds
(b) ‘Bigger thread’ variety of cotton with better tensile
strength
(c) produced by ‘biotechnology’ using restriction enzymes
and ligases
(d) carrying an endotoxin gene from Bacillus
thuringiensis
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Master The NCERT > BIOLOGY (Vol-II )
250
58 Trichoderma species, free-living fungi, are present in
root ecosystems are potentially useful as
(a)
(b)
(c)
(d)
biopesticides
biofertilisers
methanogens
vectors for genetic engineering
agent in the treatment of plant disease?
NEET 2019
(b) Anabaena
(d) Trichoderma
host specificity
narrow spectrum applications
effects on non-target insects
utility in IPM programme
(a)
(b)
(c)
(d)
NEET (Odisha) 2019
species-specific and symbiotic
free-living and broad spectrum
narrow spectrum and symbiotic
species-specific and inactive on non-target organisms
out biological control of pests/diseases using
microbes?
CBSE-AIPMT 2012
(a) Trichoderma sp., against certain plant pathogens
(b) Nucleopolyhedrovirus against white rust in Brassica
(c) Bt cotton to increase cotton yield
(d) Ladybird beetle against aphids in mustard
63 Select the correct group of biocontrol agents.
NEET 2019
(a) Trichoderma, Baculovirus, Bacillus thuringiensis
(b) Oscillatoria, Rhizobium, Trichoderma
(c) Nostoc, Azospirillum, Nucleopolyhedrovirus
(d) Bacillus thuringiensis, Tobacco mosaic virus, Aphids
64 Organic farming includes
use of fertilisers and pesticides of biological origin
IPM (Integrated Pest Management)
locally developed pest resistant varieties
All of the above
65 The organisms which are used to enrich the nutrient
quality of the soil are
(a) bacteria
(c) fungi
(b) cyanobacteria
(d) All of these
66 The most important of the symbiotic nitrogen-fixing
bacteria, which forms nodules on the roots of legume
plants is
(a) Aspergillus
(c) Penicillium
(d) All of these
69 The symbiotic association of fungi with the roots of
(a) eubacteria
(c) mycorrhiza
62 Which one of the following is an example of carrying
(a)
(b)
(c)
(d)
(b) I and III (c) II and III
higher plants is called
61 A biocontrol agent to be a part of an integrated pest
management should be
nitrogen-fixing bacteria?
I. Rhizobium
II. Azospirillum
III. Azotobacter
Choose the correct option.
(a) I and II
60 Baculoviruses (Nucleopolyhedrovirus) do not show
(a)
(b)
(c)
(d)
Aspergillus and Rhizopus
Rhizobium and Rhizopus
Cyanobacteria and Rhizobium
Aspergillus and Cyanobacteria
68 Which of the following belongs to free-living
59 Which of the following can be used as a biocontrol
(a) Chlorella
(c) Lactobacillus
(a)
(b)
(c)
(d)
(b) Rhizobium
(d) Streptococcus
67 Among the following pairs of microbes, which pair
has both the microbes that can be used as
biofertilisers?
NEET (Odisha) 2019
(b) actinomycetes
(d) lichen
70 The most common fungal partner of mycorrhiza
belongs to genus
(a) Azotobacter (b) Glomus (c) Azolla
(d) Frankia
71 Which one of the following helps in absorption of
phosphorus from soil?
(a) Nostoc (b) Anabaena
(c) Glomus
(d) Yeast
72 Which of the following are the part or example of
symbiotic mutualistic association?
(a) Rhizobium
(b) Mycorrhiza
(c) Both (a) and (b)
(d) Oscillatoria
73 Which of the following is cyanobacteria and fix
atmospheric nitrogen?
(a) Oscillatoria
(b) Nostoc
(c) Anabaena
(d) All of these
74 Which of the following is common to Azospirillum,
Anabaena, Nostoc and Oscillatoria?
(a) N2 -fixer microbes
(c) Both (a) and (b)
(b) Prokaryotic organism
(d) Eukaryotic organism
75 Which of the following serves as biofertiliser in
paddy fields?
(a) Anabaena
(c) Nostoc
(b) Azospirillum
(d) Both (a) and (c)
76 Azolla is used as a biofertiliser because it AIIMS 2018
(a)
(b)
(c)
(d)
has association of mycorrhiza
multiplies at faster rate to produce massive biomass
has association of nitrogen-fixing Rhizobium
has association of nitrogen-fixing cyanobacteria
77 A biocontrol agent used for pest butterfly caterpillars is
(a) Trichoderma
(c) Pseudomonas
(b) Bacillus thuringiensis
(d) Rhizobium
78 Select the group of organisms that are used as
biofertilisers in organic farming.
(a) Clostridium, Beijerinckia, Glomus and Anabaena
(b) Trichoderma, Baculovirus and B. thuringiensis
(c) Nostoc, Azolla pinnata and Tobacco mosaic virus
(d) Penicillium, Streptococcus and Aspergillus
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251
NEET
SPECIAL TYPES QUESTIONS
I. Assertion and Reason
■ Direction (Q. No. 79-87) In each of the following
questions, a statement of Assertion (A) is given by
corresponding statement of Reason (R). Of the statements,
mark the correct answer as
(a) If both A and R are true and R is the correct explanation of
A
(b) If both A and R are true, but R is not correct explanation of
A
(c) If A is true, but R is false
(d) If A is false, but R is true
79 Assertion (A) Besides curdling of milk, LAB also
80
81
82
83
84
85
86
improve curd’s nutritional quality.
Reason (R) LAB, when presents in human stomach,
check disease causing microbes.
Assertion (A) Biogas is used as fuel for cooking and
lighting.
Reason (R) It is considered as an ecofriendly and a
pollution free source of energy.
Assertion (A) Disadvantages of synthetic pesticides
can be overcome by the use of biopesticides.
Reason (R) Biopesticides control weeds and pest
without causing any damage to living organisms.
Assertion (A) Chemical pesticides are preferred over
biopesticides.
Reason (R) Chemical pesticides are mostly
expensive, hazardous and pollute the atmosphere.
Assertion (A) Leguminous plants are best preferred
in rotation of crops.
Reason (R) They have root nodules, which have
nitrogen-fixing bacteria Clostridium.
Assertion (A) Use of fertilisers greatly enhances crop
productivity.
Reason (R) Irrigation is very important in increasing
crop productivity.
Assertion (A) Beer and wine are called soft liquours.
Reason (R) These beverages have lower percentage
of alcohol.
Assertion (A) An organ transplant patient is
administered regular dose of cyclosporin-A.
Reason (R) Cyclosporin-A is an immunosuppresant
agent.
87 Assertion (A) Baculoviruses are broad spectrum
insecticides.
Reason (R) These viruses are excellent choices for
biocontrol in an ecologically sensitive area for
integrated pest management.
II. Statement Based Questions
88 Which of the statement given below is incorrect?
(a) Yeast is used in making bread and beverages is a
prokaryotic fungus
(b) Streptokinase is produced by Streptococcus and
modified by genetic engineering is used as a clot
buster
(c) Lipases are added in detergent for removing oily stains
from laundry
(d) Pectinases are used in clearing of bottled fruit juices
89 Which of the following statements is incorrect?
(a) Methanogens are present in human intestine and acts on
fibrous component of food
(b) Methanobacterium is a methanogenic bacteria
(c) Methanogens play an important role in the nutrition of
cattle
(d) Gobar gas is rich in Methanobacterium
90 Which of the following statements is correct?
(a) Ethanol is produced by the fermentation of malted
cereals and fruit juices
(b) Wine is produced without distillation
(c) Saccharomyces is used for bread making
(d) All of the above
91 Which of the following statement (s) is/are correct
with regard to biocontrol agents?
(a) Ladybird beetles and dragonflies are used to get rid of
aphids and mosquitoes, respectively
(b) Bacillus thuringiensis bacteria are used to control
butterfly and caterpillars
(c) Trichoderma species are used to control several plant
pathogens
(d) All of the above
92 Which of the following statements about
methanogens is incorrect?
NEET (Odisha) 2019
(a) They can be used to produce biogas
(b) They are found in the rumen of cattle and their excreta
(c) They grow aerobically and breakdown cellulose rich
food
(d) They produce methane gas
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93 Which of the following statement is/are correct?
(a) Biochemical Oxygen Demand (BOD) represents the
amount of dissolved oxygen that would be consumed if
all the organic matter in 1 L of water were oxidised by
microorganism
(b) Sewage water is treated to reduce its BOD
(c) High value of BOD means the water is less polluted by
organic matter
(d) Both (a) and (b)
94 Benefits of mycorrhizae are indicated by which
statement?
(a) It shows resistance to root borne pathogen
(b) It shows tolerance to salinity and pathogen
(c) It helps in the overall increase in the plant growth and
development
(d) All of the above
95 Which of the following statements regarding
baculoviruses as biocontrol agents are correct?
(a) Baculoviruses are pathogens that attack insects and
other arthropods
(b) Most of these biocontrol agents belong to the genus
Nucleopolyhedrovirus
(c) They do not harm plants mammals, birds, fish and other
non-target insects
(d) All of the above
96 Consider the following statements about organic
farming. Which of the statement given below is
correct?
(a) Organic farming promotes the use of crop rotations,
cover crops and encourages balanced host/predator
relationships
(b) Integrated pest, weed management and soil
conservation systems are valuable tools of an organic
farm
(c) Organic farming protects the environment, minimise
soil degradation and erosion and decrease pollution
(d) All of the above
97 Consider the following statements. Which of the
statement given below is incorrect?
(a) Microbes are also used to ferment fish, soybean and
bamboo shoots to make foods
(b) Different varieties of cheese are known by their
characteristic texture, flavour and taste, the specificity
coming from the microbe used
(c) Trichoderma sp., free-living fungi, are present in root
ecosystems where they act against several plant
pathogens
(d) Rhizobium is a symbiotic bacterium that lives in the
stem of legumes
98 Which of the following statement(s) represents the
main benefits of LAB?
I. Increase vitamin-B12 amount, thus increasing nutrient
quality of milk.
II. Check disease causing microbes in stomach.
Choose the correct option.
(a) Only I
(c) I and II
(b) Only II
(d) None of these
99 Consider the following statements.
I. Antibiotics are chemical substances produced by some
microorganisms which can kill or retard the growth of
other disease-causing microorganisms.
II. Penicillin was the first antibiotic discovered by
Alexander Fleming (1928), while working on
bacterium Staphylococcus aureus.
III. The function of penicillin as an antibiotic was
established by Ernst Chain and Howard Florey.
Which of the statements given above are correct?
(a) I and II
(c) II and III
(b) I and III
(d) I, II and III
100 Which of the following statements are correct?
I. Wine and beer are produced without distillation of
fermented broth.
II. Byproducts of alcoholic fermentation are CO2 and
methane.
III. Penicillium species is used for fermenting malted
cereals to produce alcohol.
Choose the correct option.
(a) Only I
(b) I and II (c) II and III
(d) Only III
101 Sewage or municipal waste should not be directly
passed into rivers, streams and other water bodies
because
I. it contains human excreta and other organic waste.
II. it contains a number of pathogenic microbes.
Which of the statement (s) given above is/are correct?
(a) Only I
(c) I and II
(b) Only II
(d) None of these
102 Consider the following statements.
I. After primary treatment of sewage, all solids that settle
down forms the primary sludge and the supernatant
form the effluent.
II. Spent slurry of biogas plant is used as fertiliser.
Which of the statements given above are correct?
(a) Only I
(c) Only II
(b) I and II
(d) None of these
103 Consider the following statements about, secondary
sewage treatment.
I. In secondary treatment, useful aerobic microbes grow
rapidly and form flocs. Flocs are masses of bacteria
associated with fungal filaments to form mesh-like
structures.
II. The growing microbes consume organic matter and
thus, reduce the biochemical oxygen demand.
When BOD of sewage has reduced, the effluent is
passed into settling tank.
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CHAPTER 10 > Microbes in Human Welfare
III. In settling tank, the bacterial flocs settle and the
sediment is called activated sludge.
IV. A small part of the sludge is used as an inoculum in the
aeration tank and the remaining part is passed into
large tanks called anaerobic sludge digesters.
V. In the digesters, heterotrophic microbes anaerobically
digest bacteria and fungi in sludge producing mixture
of gases such as, carbon dioxide, nitrogen and carbon
monoxide which form the biogas.
Which of the statements given above are correct?
(a) I, II, III and IV
(c) II, III, IV and V
(b) I, III, IV and V
(d) I, II, III, IV and V
104 Consider the following statements about Bt.
I. The bacteria Bacillus thuringiensis (Bt) are used to
control butterfly catterpillars.
II. Fresh spores of Bt are mixed with water and sprayed on
to vulnerable plants such as brassicas and fruit trees.
III. Insect larvae, after eating Bt ,are killed by the toxin
released in their gut.
IV. Bt toxin genes have been introduced into plants to
provide resistance to pests.
253
(a)
(b)
(c)
(d)
Both statements I and II are correct
Statement I is correct, but statement II is incorrect
Statement I is incorrect, but statement II is correct
Both statements I and II are incorrect
108 Read the following statements about disadvantages of
chemical agents.
I. Chemicals are toxic and harmful to human beings and
animals.
II. Chemicals pollute the environment and plants.
III. Weedicides used to remove weeds also pollute the soil.
Choose the correct option.
(a) I, II and III
(c) I and III
(b) I and II
(d) II and III
109 Read the following statements.
AIIMS 2018
I. Colostrum is recommended for the newborns because
it is rich in antigens.
II. Chikungunya is caused by a Gram negative bacterium.
III. Tissue culture has proved useful in obtaining
virus-free plants.
IV. Beer is manufactured by distillation of fermented
grapes.
Which of the statements given above are correct?
How many of the statement(s) is/are correct ?
(a) I, II and III
(c) II, III and IV
(a) Two
(b) I, III and IV
(d) I, II, III and IV
105 Which of the following statement(s) is correct?
I. The dough, which is used for making bread, is
fermented using Baker’s yeast, i.e. Saccharomyces
cerevisiae.
II. Production on an industrial scale, requires growing
microbes in very large vessels called fermentors.
III. The municipal wastewater is also called sewage.
IV. It is necessary to treat sewage in Sewage Treatment
Plants (STPs) to make it less polluting.
Which of the statements given above are correct?
(a) I and II
(c) I, II and IV
(b) Only III
(d) I, II, III and IV
106 Which of the following is/are the approache(s) for
biological farming?
I. Familiarity with various life forms inhabiting the field.
II. Gain knowledge about the life cycles, patterns of
feeding and habitat of predators and pests.
Choose the correct option.
(a) Only I
(c) I and II
(b) Only II
(d) None of these
(b) One
(c) Three
(d) Four
III. Matching Type Questions
110 Match the following columns.
Column I
(Organisms)
Column II
(Uses)
A.
Lactobacillus
1.
Roquefort cheese
B.
Saccharomyces cerevisiae
2.
Swiss cheese
C.
Propionibacterium shermanii
3.
Bread
D.
Penicillium roqueforti
4.
Milk into curd
Codes
A
(a) 4
(c) 4
B
3
1
C
2
2
D
1
3
A
(b) 3
(d) 1
B
2
4
C
1
3
D
4
2
111 Match the following columns.
Column I
Column II
A.
Azolla
1.
Symbiotic N2-fixer
B.
Rotenone
2.
Symbiotic association with N2
-fixing cyanobacteria
C.
Crotolaria juncea
3.
Natural insecticide
D.
Frankia
4.
Green manure
Codes
A
(a) 2
(b) 2
(c) 2
(d) 1
B
3
4
1
3
107 Read the following statements and select the correct
option.
I. Biocontrol refers to the use of biological methods for
controlling plant diseases and pests.
II. Use of biocontrol measures will greatly reduce our
dependence on toxic chemicals and pesticides.
C
4
3
4
4
D
1
1
3
2
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254
112 Match the following columns.
NEET 2016
Column I
A.
1.
Trichoderma
B.
Cyclosporin
2.
Clostridium
C.
Statins
3.
Aspergillus
D.
Butyric acid
4.
Monascus
Codes
A
(a) 3
(c) 1
B
1
4
Column I
A. Symbiotic nitrogen-fixing
bacteria
B. Dragonflies
C. Bacillus thuringiensis
D. Free-living N 2-fixing bacteria
Column II
Citric acid
C
2
2
D
4
3
A
(b) 3
(d) 3
B
1
4
C
4
1
D
2
2
113 Match the following columns.
Column I
Column II
Mycorrhiza
1.
Nucleopolyhedrovirus
B.
Bacillus thuringiensis
2.
Rhizobium
C.
Root nodules
3.
Bt cotton
D.
Baculovirus
4.
Phosphorus nutrition
B
3
4
C
2
1
D
1
2
A
(b) 3
(d) 4
B
2
1
C
1
2
D
4
3
114 Match the following list of microbes and their
importance.
CBSE-AIPMT 2015
A. Saccharomyces
cerevisiae
1.
Production of
immunosuppressive agents
B. Monascus purpureus
2.
Ripening of Swiss cheese
C. Trichoderma
polysporum
3.
Commercial production of
ethanol
D. Propionibacterium
shermanii
Codes
A
(a) 3
(b) 4
(c) 4
(d) 3
Codes
A
(a) 1
(c) 2
4.
B
4
1
C
3
4
D
2
3
Column II
1. Mosquitoes
2. Rhizobium
3. Azotobacter
4. Butterfly, caterpillars
A
(b) 4
(d) 2
B
3
1
C
2
3
116 Match the following columns.
A.
Codes
A
(a) 4
(c) 3
115 Match the following columns.
Production of bloodcholesterol lowering agents
A.
B.
C.
D.
Column I
Lactobacillus
Saccharomyces cerevisiae
Aspergillus niger
Acetobacter aceti
D
1
4
NEET 2019
1.
2.
3.
4.
Column II
Cheese
Curd
Citric acid
Bread
5. Acetic acid
Codes
A
(a) 2
(c) 2
B
4
1
C
3
3
D
5
5
A
(b) 3
(d) 2
B
4
4
C
5
5
D
1
3
117 Match Column I (Antibiotic) with Column II
(Source).
AIIMS 2018
Column I
Column II
A. Fumagillin
1. Gliocladium virens
B. Bacitracin
2. Streptomyces griseus
C. Streptomycin
3. Bacillus polymyxa
D. Viridin
4. Aspergillus fumigatus
E. Polymixin
5. Bacillus licheniformis
Codes
B
4
3
2
1
C D
1 2
2 1
1 3
4 2
(a)
(b)
(c)
(d)
A
1
4
3
2
B
2
5
1
3
C
3
2
4
5
D
4
1
2
4
E
5
3
5
1
NCERT &NCERT Exemplar
MULTIPLE CHOICE QUESTIONS
NCERT
118 Which one of the following processes evidently
prove that microbes release gases during
metabolism?
(a) Making of curd from milk
(b) Rising of dough by yeast
(c) Making of alcohol from malt
(d) None of the above
119 Lactic acid bacteria are found in
(a) milk
(c) Both (a) and (b)
(b) curd
(d) None of these
120 Which of the following is antibiotic producing fungi?
(a) Monascus
(b) Peronospora
(c) Penicillium
(d) Rhizopus
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121 Find out the incorrect pair from the following.
(a) Biogas—Methanogens (b) Penicillium — Antibiotic
(c) Curd — LAB
(d) Citric acid — Trichoderma
122 Read the following and choose the incorrect statement.
(a) Most biofertilisers are obtained from microbes
(b) VAM is the example of biofertiliser giving organism
(c) SCP is used as source of biofertiliser
(d) None of the above
NCERT Exemplar
123 The vitamin whose content increases following the
conversion of milk into curd by lactic acid bacteria is
(a) vitamin-C
(c) vitamin-B12
(b) vitamin-D
(d) vitamin-E
124 Wastewater treatment generates a large quantity of
sludge, which can be treated by
(a) anaerobic digesters
(c) chemicals
(b) floc
(d) oxidation pond
(a) rumen of cattle
(b) gobar gas plant
(c) bottom of water-logged paddy fields
(d) activated sludge
126 Match the following columns of bacteria and their
commercially important products.
Aspergillus niger
1.
Lactic acid
B.
Acetobacter aceti
2.
Butyric acid
C.
Clostridium butylicum
3.
Acetic acid
D.
Lactobacillus
4.
Citric acid
A B C D
(b) 2 4 3 1
(d) 4 1 3 2
127 Which one of the following alcoholic drinks is
produced without distillation?
(a) Wine
130 Big holes in Swiss cheese are made by
(a) a machine
(b) a bacterium that produces methane gas
(c) a bacterium producing a large amount of carbon
dioxide
(d) a fungus that releases a lot of gases during its metabolic
activities
131 The residue left after methane production from cattle
dung is
(a) burnt
(c) used as manure
(b) burried in land fills
(d) used in civil construction
132 Methanogens do not produce
(a) oxygen
(c) hydrogen sulphide
(b) methane
(d) carbon dioxide
133 Activated sludge should have the ability to settle
(a) be rapidly pumped back from sedimentation tank to
aeration tank
(b) absorb pathogenic bacteria present in wastewater, while
sinking to the bottom of the settling tank
(c) be discarded and anaerobically digested
(d) absorb colloidal organic matter
134 Match the following list of bioactive substances and
Column II
(Products)
A.
Codes
A B C D
(a) 2 3 4 1
(c) 4 3 2 1
(c) Flocs would increase in size as anaerobic bacteria
would grow around flocs
(d) Protozoa would grow in large numbers
quickly, so that it can
125 Methanogenic bacteria are not found in
Column I
(Bacterium)
255
(b) Whisky (c) Rum
(d) Brandy
128 The free-living fungus Trichoderma can be used for
(a) killing insects
(b) biological control of plant diseases
(c) controlling butterfly caterpillars
(d) producing antibiotics
129 What would happen if oxygen availability to
activated sludge flocs is reduced?
(a) It will slow down the rate of degradation of organic
matter
(b) The centre of flocs will become anoxic, which would
cause death of bacteria and eventually breakage of
flocs
their roles.
Column I
(Bioactive substances)
Column II
(Roles)
A. Statin
1. Removal of oil stains
B.
Cyclosporin-A
2. Removal of clots from blood
vessels
C.
Streptokinase
3. Lowering of blood
cholesterol
D. Lipase
Codes
A
(a) 2
(c) 4
B
3
1
4. Immunosuppressive agent
C
1
3
D
4
2
A
(b) 4
(d) 3
B
2
4
C
1
2
D
3
1
135 The primary treatment of wastewater involves the
removal of
(a) dissolved impurities
(c) toxic substances
(b) stable particles
(d) harmful bacteria
136 BOD of wastewater is estimated by measuring the
amount of
(a) total organic matter
(b) biodegradable organic matter
(c) oxygen evolution
(d) oxygen consumption
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Master The NCERT > BIOLOGY (Vol-II )
256
137 The technology of biogas production from cow
139 Match the items in Column I and Column II and
dung was developed in India largely due to the
efforts of
choose correct answer.
(a) Gas Authority of India
(b) Oil and Natural Gas Commission
(c) Indian Agricultural Research Institute and Khadi and
Village Industries Commission
(d) Indian Oil Corporation
A.
B.
C.
D.
Column I
Ladybird
Mycorrhiza
Biological control
Biogas
Codes
A
(a) 2
(c) 4
138 Mycorrhiza does not help the host plant in
(a) enhancing its phosphorus uptake capacity
(b) increasing its tolerance to drought
(c) enhancing its resistance to root pathogens
(d) increasing its resistance to insects
B
4
1
C
3
2
D
1
3
1.
2.
3.
4.
A
(b) 3
(d) 3
Column II
Methanobacterium
Trichoderma
Aphids
Glomus
B
4
2
C
2
1
D
1
4
140 Which one of the following is not a nitrogen-fixing
organism?
(a) Anabaena (b) Nostoc (c) Azotobacter (d) Pseudomonas
Answers
‡ Mastering NCERT with MCQs
1 (d)
16 (c)
31 (a)
46 (a)
61 (d)
76 (d)
2 (b)
17 (c)
32 (c)
47 (c)
62 (a)
77 (b)
3 (a)
18 (c)
33 (c)
48 (b)
63 (a)
78 (a)
4 (b)
19 (d)
34 (b)
49 (c)
64 (d)
5 (c)
20 (b)
35 (a)
50 (c)
65 (d)
6 (b)
21 (b)
36 (a)
51 (b)
66 (b)
7 (d)
22 (d)
37 (b)
52 (c)
67 (c)
8 (a)
23 (d)
38 (c)
53 (c)
68 (c)
9 (b)
24 (a)
39 (c)
54 (b)
69 (c)
10 (a)
25 (a)
40 (d)
55 (c)
70 (b)
11 (a)
26 (d)
41 (a)
56 (a)
71 (c)
12 (c)
27 (d)
42 (d)
57 (d)
72 (c)
13 (b)
28 (d)
43 (a)
58 (a)
73 (d)
14 (b)
29 (a)
44 (a)
59 (d)
74 (c)
15 (c)
30 (d)
45 (c)
60 (c)
75 (d)
‡ NEET Special Types Questions
79 (b)
80 (b)
81 (a) 82 (d) 83 (c)
84 (b)
85 (a) 86 (a) 87 (d) 88 (a) 89 (a) 90 (d) 91 (d) 92 (c)
93 (d)
94 (d) 95 (d) 96 (d) 97 (d) 98 (c)
99 (d) 100 (a) 101 (c) 102 (b) 103 (a) 104 (d) 105 (d) 106 (c) 107 (a) 108 (a)
109 (b) 110 (a) 111 (a) 112 (b) 113 (a) 114 (a) 115 (c) 116 (a) 117 (b)
‡ NCERT & NCERT Exemplar Questions
118 (b) 119 (c)
120 (c)
121 (d) 122 (c)
133 (a) 134 (d) 135 (b) 136 (d) 137 (c)
123 (c)
124 (a) 125 (d) 126 (c)
127 (a) 128 (b) 129 (b) 130 (c)
131 (c)
132 (a)
138 (d) 139 (b) 140 (d)
Answers & Explanations
2 (b) Prions are the microscopic protein particles similar to a
7 (d) Heterotrophic bacteria are the most abundant life forms.
virus, but lack nucleic acid. These are assumed to be the
infectious agent, responsible for scrapie and certain other
degenerative diseases of the nervous system.
Many of them have a significant impact on humans, such as
these are helpful in making curd from milk, e.g.
Lactobacillus sp., and production of antibiotics, e.g.
Streptomyces sp.
10 (a) The dough, which is used for making foods such as dosa,
bread and idli are also fermented by bacteria. The puffed up
appearance of dough is due to the production of CO2 gas by
these bacteria.
12 (c) Swiss cheese is formed with the help of single strain of
Propionibacterium shermanii. Its characteristic feature is
the formation of large holes due to the production of a large
amount of CO2 .
15 (c) Bioreactor is an essential equipment required for
growing microbes on large scale, i.e. for the industrial
production of enzymes, antibiotics, beverages, etc. These
3 (a) The nutritive medium for growing bacteria and many
fungi in the laboratory is called culture media. This media
contains all the essential requirements necessary for
bacterial and fungal growth such as carbon, sugar, minerals,
etc. The growth of microbes is visible as colonies that can be
seen with the naked eyes. Such cultures are useful in studies
on microorganisms.
5 (c) Lactobacillus is added to milk which converts lactose
(sugar of milk) into lactic acid. Lactic acid causes
coagulation and partial conversion of milk protein casein to
calcium paracaseinate. These chemical changes in milk help
in its conversion into curd, yoghurt and cheese.
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large vessels provide biologically active environment
suitable for microbial production of such products.
(c) Distilled spritis are alcoholic beverages in which the
concentration of ethyl alcohol is more than the original
fermented mixture which is obtained by distillation.
These beverages are whisky, brandy and rum.
Other beverages like wine and beer are produced
without distillation.
(c) An yeast, Saccharomyces cerevisiae, is used in the
production of alcoholic beverages like wine, beer,
whisky, brandy or rum. Beverages are generally formed
by fermenting malted cereals and fruit juices with this
yeast to produce ethanol or alcohol.
(d) Penicillin was the first antibiotic to be discovered
by Alexander Fleming (1928). The antibiotic was,
however, commercially extracted by efforts of Ernst
Chain and Howard Florey. Fleming, Chain and Florey
were together awarded Nobel Prize in 1945, for this
discovery.
(d) Antibiotics have greatly improved our capacity to
treat deadly diseases such as diphtheria (gal ghotu),
whooping cough (kali khansi), plague, leprosy (kusht
rog), which is used to kill millions of people all over the
world.
(d) Only option (d) is correctly matched. Other options
are incorrectly matched and can be corrected as
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Acetobacter aceti produces acetic acid.
Methanobacterium produces methane.
Penicillium notatum produces penicillin.
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28 (d) Streptokinase produced by the bacterium
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Streptococcus and modified by genetic engineering is
used as a clot buster for removing clots from the blood
vessels of patients who have undergone myocardial
infarction leading to heart attack.
(a) Statins are the commercial blood cholesterol
lowering agents as these competitively inhibit the
enzymes involved in cholesterol synthesis. These are
obtained from the yeast, Monascus purpureus.
(c) Option (c) is incorrectly matched in the table. It can
be corrected as
Butyric acid is produced by fermentative activity of the
bacteria called Clostridium butylicum. It does not
produce lipase. Lipase is obtained from Candida
albicans.
Rest of the options contain correct matches.
(a) Primary treatment is the physical removal of large
and small particles from sewage through filtration and
sedimentation.
(c) In sewage treatment, suspended solids are removed
during primary treatment. It is also known as physical
treatment.
It consists of shredding, churning, screening and
sedimentation. Sequential filtration removes floating
and large suspended solids.
(c) In the biological treatment of sewage, flocs are
formed. These are masses of bacteria associated with
fungal filaments to form a mesh-like structure. The
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growing microbes consume organic matter and thus
reduce the Biochemical Oxygen Demand (BOD) and
lowers the level of pollutants.
(a) In the sewage treatment, when Biochemical Oxygen
Demand (BOD) of sewage has reduced, the effluent is
passed into settling tank. Here, the bacterial flocs settle
and the sediment thus formed is called activated sludge.
(a) Option (a) is correct.
Primary sludge possesses flocs of decomposer (aerobic)
microbes, which consume a major part of the organic
matter in the effluent to reduce the BOD.
(c) Primary treatment does not involve microbes. It is
the physical removal of large and small particles from
sewage.
However, secondary treatment of the effluent from the
primary settling tank is purely a biological treatment
involving microbial activity. Further, in the anaerobic
sludge digesters, heterotrophic microbes anaerobically
digest bacteria and fungi in the sludge producing
mixture of gases such as methane, hydrogen sulphide
and CO2 , which form biogas.
Thus, microbes are used in secondary treatment,
anaerobic sludge digesters and biogas production.
(a) BOD is a measure of the organic matter present in
water. Thus, greater the value of BOD in a sample of
water, more will be its polluting potential. This
indicates that the water body will be highly polluted.
(c) In order to protect the major rivers of India from
water pollution, the Ministry of Environment and
Forests, has initiated development of the sewage
treatment plants under the National River Conservation
Authority, so that only treated sewage may be
discharged in the rivers, e.g. Ganga Action Plan (GAP),
Yamuna Action Plan (YAP), Satluj Action Plan and
Gomti Action Plan.
(b) The major component of biogas is methane (about
50-68%), and it is highly inflammable. The other
gaseous components of biogas are carbon dioxide
(25-35%), hydrogen (1-7%) and rarely hydrogen
sulphide.
(c) Methanogens, particularly Methanobacterium, are
the anaerobic bacteria, which breakdown cellulosic
material to produce methane, CO2 and H2 . These are
found in the anaerobic sludge in sewage treatment
plants and rumen (a part of stomach) of cattle. These
play an important role in nutrition.
(b) Methanogens are a group of obligate anaerobic
ancient or primitive bacteria (prokaryote). These are
involved in methanogenesis and produce methane gas
(biogas) from the dung of ruminant animals.
(c) The correct option for A, B and C is (c) as
Anaerobic microbes, methanogenic bacteria, CO 2 and
methane (biogas), respectively.
In stage - I, anaerobic microorganisms, (A) bring about
enzymatic breakdown of complex organic compounds
into simple soluble compounds or monomers.
In stage -II, monomers are converted into organic acids
by fermentating microbes.
Answers & Explanations
257
CHAPTER 10 > Microbes in Human Welfare
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Answers & Explanations
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63
In stage -III, organic acids are acted upon by
methanogenic bacteria (B) to produce methane rich
mixture of gases called biogas (C).
(c) Bacillus thuringiensis is a soil bacterium used as
biocontrol agent that can control infestations by insect
pests such as butterfly, caterpillars, ants, moths, etc.
Some strains of these bacteria can kill animal and plant
parasitic nematodes, snails, protozoans, etc.
(a) The Bt toxin is an inactive protoxin, which gets
activated due to the alkaline pH of the insect gut.
Proteins are solubilised and proteolytically processed
when exposed to alkaline pH and thus are activated.
The toxins then attack the gut cells of the insect,
creating holes in the lining casusing lysis and death of
the insect.
(d) In Bt cotton, Bt means carrying an endotoxin gene
from Bacillus thuringiensis.
Specific Bt toxin genes were isolated from Bacillus
thuringiensis and incorporated into several crop plants
such as cotton, corn, etc. The toxin is coded by a gene
named cry and imparts resistance to a wide range of
insect pests.
(d) Trichoderma can be used as a biocontrol agent of
several plant pathogens. It is a filamentous soil fungus
having mycoparasitic activity.
On the other hand, Anabaena helps in nitrogen-fixation,
Lactobacillus helps in the production of organic acid,
e.g. lactic acid and Chlorella is a single cell protein,
which acts as food supplement.
(c) Baculoviruses (Nucleopolyhedrovirus) do not show
effect on non-target insects. These viruses are excellent
candidates for species-specific, narrow spectrum
insecticidal applications. These have been known to
shown no negative impacts on plants, mammals, birds,
fish or even on non-target insects.
(d) For a biocontrol agent to be a part of an Integrated
Pest Management (IPM) programme, it should be
species-specific and inactive or have no negative
impacts on non-target organisms like plants, mammals,
birds, fish and even another non-target insects. It should
kill only targeted insects/pests (organisms).
(a) Option (a) gives an example of biological
pest/disease control being carried out by microbes.
Trichoderma species are effective biocontrol agents of
several plant pathogens. They are free-living fungi that
are very common in the root ecosystems.
(a) The correct group of biocontrol agents is given by
option (a), i.e. Trichoderma, baculovirus and Bacillus
thuringiensis.
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Baculoviruses are pathogens that attack insects and
other arthropods. Most of baculoviruses used as
biocontrol agent belong to the
genus–Nucleopolyhedrovirus.
Trichoderma is extensively used against pathogenic
fungi which causes soil-borne diseases.
Bacillus thuringiensis secretes toxin cyrstals which kill
the insect larvae.
64 (d) Organic farming includes several methods to
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enhance soil fertility. In such farming, methods of
biological origin are used, e.g. biopesticide,
biofertilisers, IPM (Integrated Pest Management),
locally developed pest resistant varieties, green manure,
etc.
(b) Rhizobium is a soil bacterium that fixes nitrogen in
symbiotic association with root nodules of legumes
(Fabaceae). Rhizobium requires a plant host, as it cannot
independently fix atmospheric nitrogen.
(c) Cyanobacteria and Rhizobium can be used as
biofertilisers. Biofertilisers are the organisms that enrich
the nutrient quality of the soil. Whereas, Aspergillus
and Rhizopus are not used as biofertilisers.
(c) Azospirillum and Azotobacter are free-living
nitrogen-fixing bacteria. These bacteria fix atmospheric
nitrogen in the soil and make it available for the higher
plants. On the other hand, Rhizobium is the symbiotic
nitrogen-fixing bacterium.
(c) A mycorrhiza is a symbiotic (mutually beneficial)
association between a fungus and the roots of a vascular
(higher) plant. These are important components of soil
life and soil chemistry.
(c) Genus–Glomus forms mycorrhiza with roots of
higher plants. It is a fungus which helps in nutrient
uptake from soil, mainly aiding the absorption of
phosphorus.
( d ) Nostoc, Anabaena and Oscillatoria are all
cyanobacteria which fix atmospheric nitrogen and
increase the organic matter of the soil through
photosynthetic activity.
(d) Nostoc and Anabaena are cyanobacteria, which
serve as important biofertilisers in paddy fields. These
fix atmospheric nitrogen and increase the organic matter
of soil through their photosynthetic activity. These also
increase the soil fertility by adding organic matter to the
soil.
(d) Azolla is a pteridophyte and it is used as a
biofertiliser because it has association with a
nitrogen-fixing cyanobacteria called Anabaena azollae.
(b) Bacillus thuringiensis is the most effective
biocontrol agent for insect pests such as butterfly
caterpillars. Spores of this bacterium produce a toxic
insecticidal protein called Cry. These proteins enter the
host’s body and reach gut where on activation they kill
the host by lysis.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion. The correct
explanation is
LAB also improve curd’s nutritional quality during
coagulation of milk by increasing the content of
vitamin-B12 and other nutrients. It is present in curd and
also checks the growth of disease causing microbes in
stomach and other parts of digestive tract in humans.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion. The correct
explanation is as follows
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Baculoviruses are species-specific narrow spectrum
insecticides.
These features make them an excellent choice for
conservation of beneficial insects during integrated pest
management programme in an ecologically sensitive
area.
(a) The statement in option (a) is incorrect. It can be
corrected as
Yeast is used in making bread and beverages is a type
of eukaryotic fungus.
Rest of the statements are correct.
(a) The statement in option (a) is incorrect and can be
corrected as
Methanogens are present in the rumen (a part of
stomach) of cattle (runminant) where it acts on the
cellulosic content to yield a methane rich mixtrue of
gases.
Rest of the statements are correct.
(c) The statement in option (c) is incorrect and can be
corrected as
Certain bacteria, which grow anaerobically on cellulosic
material, produce large amount of methane along with
CO 2 and H 2 .
These bacteria are collectively called methanogens and
one such example is Methanobacterium.
Rest of the statements in other options are correct.
(d) The statements in options (a) and (b) are correct,
while the statement in option (c) is incorrect. It can be
corrected as
High value of BOD means that the water body is highly
polluted by organic matter.
(d) The statement in option (d) is incorrect and can be
corrected as
Rhizobium is a symbiotic bacterium that lives in the root
nodules of legumes and fixes atmospheric nitrogen.
Rest of the statements are correct.
(a) Statement I is correct. The correct form of the
incorrect statements II and III are
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The byproducts of alcoholic fermentation are CO 2 and
ethanol (not methane).
Saccharomyces cerevisiae is used for fermenting
malted cereals to produce alcohol. Penicillium on the
other hand is used for the production of the antibiotic,
penicillin.
103 (a) Statements I, II, III and IV are correct, but
statement V is incorrect and it can be corrected as
In the digesters, heterotrophic microbes anaerobically
digest the bacteria and fungi in the sludge. During this
digestion, bacteria produce mixture of gases such as
methane, hydrogen sulphide and CO2 , which form
biogas.
106 (c) Both the approaches given in statements I and II are
correct for biological farming.
An important part of the biological farming approach is
to become familiar with the various life forms that
inhabit the field, predators as well as pests and also their
Answers & Explanations
81
Biogas is used as fuel for heating, cooking, lighting
because it is flammable. It is an alternative of firewood,
kerosene, etc., and acts as an ecofriendly and a pollution
free source of energy.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Synthetic pesticides are chemicals which have several
disadvantages such as their high cost, long term
pollution, toxicity and tendency to accumulate in living
organisms, etc. These disadvantages can be overcome
by the use of biopesticides that are simple components
of biological origin because these cause no damage or
toxicity in living organisms.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
Chemical pesticides are not preferred over
biopesticides. This is because chemical fertilisers are
generally more expensive and hazardous in nature.
These unnecessarily pollute the natural resources like
soil and water over a long time.
(c) Assertion is true, but Reason is false. Reason can be
corrected as
Leguminous crops are grown in rotation of crops. These
plants have the ability to fix atmospheric nitrogen to
form nitrogen compounds through the help of certain
bacteria, like Rhizobium, present in their root nodules.
In rotation of crops, leguminous crops like pulses,
beans, peas, groundnut and Bengal gram are sown in
between the seasons of cereal crops like wheat, maize
and pearl millet. These are leguminous plants when
grown alternately with non-leguminous plants restore
the fertility of the soil.
(b) Both Assertion and Reason are true, but Reason is
not the correct explanation of Assertion.
Use of fertilisers greatly enhances crop productivity by
addition of nitrogen, phosphorus and potassium to the
soil. Irrigation practices are also helpful in enhancing
the crop yield by fulfilling the demand of water in
crops. In this way, both fertilisers and irrigation are
equally important for high crop yield.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
Beer and wine are called as soft liquours because these
are produced without undergoing distillation and have
lower percentage of alcohol content as compared to
hard liquours like rum, whisky, brandy, etc.
(a) Both Assertion and Reason are true and Reason is
the correct explanation of Assertion.
An organ transplant patient is kept on a regular dose of
cyclosporin-A to reduce the risk of transplant rejection.
Cyclosporin-A is used as immunosuppessive agent in
organ transplanted patients to inhibit the activation of
T-cells and interferes with the destruction of non-self
cells. It thus, increases the chances of graft being
accepted recepient’s body.
(d) Assertion is false, but Reason is true. Assertion can
be corrected as
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Master The NCERT > BIOLOGY (Vol-II )
260
life cycles, patterns of feeding and the habitats that they
prefer. This will help to develop appropriate means of
biocontrol.
109 (b) Only one statement, i.e. statement III is correct.
Rest statements are incorrect and can be corrected as
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Colostrum is the first breastmilk of mother, which
contains antibodies (especially IgA). It provides
immunity to infants against various pathogens.
Chikungunya is caused by chikungunya virus.
Beer is manufactured without distillation, by
fermentation of barley malt by yeast.
118 (b) The process given in option (b) evidently proves that
microbes release gases during metabolism. Rising of
dough occurs by the activity of yeast metabolism. It
happens due to the bubble formation because of the
release of CO2 . It is the easiest way to understand that
yeast releases CO2 .
119 (c) Lactic Acid Bacteria (LAB) found in curd and
especially, Lactobacillus casei are abundantly found in
raw milk. These are commonly used as probiotics.
121 (d) Option (d) shows the incorrect pair and can be
corrected as
Citric acid–Aspergillus niger.
Rest of the options contain the correct pairs.
122 (c) The statement in option (c) is incorrect and can be
corrected as
Single Cell Protein (SCP) is a source of protein, e.g.
Spirulina products.
Rest of the statements are correct.
123 (c) Microorganisms such as Lactobacillus and others
commonly called Lactic Acid Bacteria (LAB) grow in
milk and convert it into curd. LAB improve nutritional
quality of milk and curd by increasing the content of
vitamin-B12 .
124 (a) Wastewater treatment generates a large quantity of
sludge, which is further treated by anaerobic digesters.
These are large heated tanks in which various
methanogenic anaerobic bacteria digest the bacteria and
fungi present in the sludge.
Answers & Explanations
125 (d) Methanogenic bacteria (that produce methane) are
not found in activated sludge. The microbes present in
the activated sludge are aerobic bacteria that grow
rapidly and form flocs. On the other hand methanogens
are the anaerobic bacteria present in anaerobic sludge
digesters.
127 (a) Wine is an alcoholic drink produced without
distillation whereas whisky, brandy and rum are
produced by distillation of the fermented broth.
128 (b) Trichoderma species are free-living fungi that are
very common in root ecosystems or soil.
These are effective biocontrol agents of several plant
pathogens.
129 (b) Activated sludge microorganisms need oxygen as
they oxidise wastes to obtain energy for growth. Thus,
if oxygen availability to activated sludge flocs is
reduced, insufficient oxygen (anoxic) conditions will
slow down or kill off aerobic microorganisms, make
facultative organisms work less efficiently and
ultimately lead to the breakage of flocs.
130 (c) The large holes in ‘Swiss cheese’ are due to the
production of a large amount of CO2 by a bacterium
named, Propionibacterium shermanii.
132 (a) In the digesters (during secondary treatment of
waste water), heterotrophic microbes like methanogens
anaerobically digest biodegradable waste in sludge
producing mixture of gases such as methane, hydrogen
sulphide and CO2 which form the biogas. Thus, O2 is
not produced by methanogens.
133 (a) Activated sludge should have the ability to settle
quickly, so that it can be ready pumped back from
sedimentation tank to aeration tank because a small part
of the activated sludge is used as inoculum in the
aeration tank.
135 (b) The primary treatment of wastewater involves
physical removal of both larger and small particles
(stable particles) from the sewage through filtration
and sedimentation. These are removed in stages,
initially, floating debris is removed by sequential
filtration. Then, the grit (soil and small pebbles) are
removed by sedimentation.
138 (d) Mycorrhiza does not help the host plant in
increasing its resistance to insects. Infact, plants having
such associations show resistance only to root-borne
plant pathogens, tolerance to salinity and drought and
an overall increase in plant growth and development.
140 (d) Pseudomonas is a denitrifying bacterium, which
converts ammonia and nitrates into free nitrogen, i.e. to
liberate free nitrogen in the environment through
nitrogen cycle. Therefore, it is not a nitrogen-fixing
organism.
Other options (a), (b) and (c) show nitrogen-fixing
organisms.
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CHAPTER > 11
Biotechnology :
Principles and
Processes
NEET
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Å
Å
KEY NOTES
Biotechnology is the technique of using living organisms or
enzymes from organisms to produce products and processes
useful to humans.
Biotechnology deals with the large scale production and
marketing of products such as enzymes, insulin or
antibiotics, etc., that are of importance to mankind.
The European Federation of Biotechnology (EFB) has given
a definition of biotechnology as, the integration of natural
science and organisms cells, parts thereof and molecular
analogues for products and services’.
Å
Å
Principles of Biotechnology
Following two core techniques gave birth to modern
biotechnology
Å Genetic engineering It is the alteration of the chemistry of
genetic material (DNA/RNA), introduce these into host
organisms and consequently change the phenotype of the
host organism.
Å Bioprocess engineering It is the maintenance of sterile
conditions in order to enable the growth of only desired
microbes or eukaryotic cells in large quantities for the
production of antibiotics, enzymes, hormones, vaccines, etc.
Å
Å
Genetic Engineering
Å
Å
It is the deliberate modification of an organism’s DNA, using
various techniques. This altered DNA (recombinant DNA) is
then introduced into host organisms to change their
phenotype.
This is followed by growing this genetically modified cell in
large quantities, by maintaining sterile environment, for the
manufacture of biotechnological products like antibiotics,
vaccines, enzymes, etc.
Å
Techniques of genetic engineering include construction of
recombinant DNA, gene cloning and gene transfer. These
techniques allow the isolation and introduction of a set of
desirable genes without introducing undesirable genes into
the target organism.
Origin of replication (ori) is a specific DNA sequence in the
chromosome which can initiate DNA replication. The foreign
DNA introduced into the host genome has to be linked the
origin of replication in the host chromosome for the gene to
be able to multiply. This is also known as cloning which
involves making multiple identical copies of any template
DNA. If the foreign gene is not linked to the ori sequence it
may not be able to multiply.
In 1972, the first recombinant DNA was constructed by
Stanley Cohen and Herbert Boyer. They isolated the
antibiotic resistance gene by cutting out a piece of DNA from
a plasmid (autonomously replicating circular extrachromosomal DNA) of Salmonella typhimurium. The cutting
of DNA at specific locations become possible with the help
of restriction enzymes (molecular scissors).
The cut pieces of DNA were then linked with the plasmid
DNA using DNA ligase enzyme. These plasmids act as
vectors to transfer the piece of DNA attached to it into the
host organism. This makes a new circular autonomously
replicating DNA created in vitro and is known as the
recombinant DNA.
The recombinant DNA is transferred into Escherichia coli, a
bacterium closely related to Salmonella, where it replicates
using the new host’s DNA polymerase enzyme and makes
multiple copies of itself. It also produces multiple copies of
the antibiotic resistance gene in the new host (E. coli). This
process is called as cloning of antibiotic resistance gene in
E. coli.
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Master The NCERT > BIOLOGY (Vol-II)
262
Å
There are three basic steps involved in genetically
modifying an organism
n
Identification of DNA with desirable genes.
n
Introduction of the identified DNA into the host.
Types of Restriction Enzyme
Å
The restriction enzymes can be of three types, on the basis
of their chemical and physiological properties.
Type II
Enzyme
Type III
Enzyme
Bifunctional enzyme
with 3 subunits
Separate
endonuclease
and methylase
Bifunctional
enzyme with
2 subunits
Recognition
site
Genetic engineering or recombinant DNA technology can be
accomplished only if we have the key tools, i.e. restriction
enzymes, polymerase enzymes, ligases, vectors and the host
organism.
Bipartite and
asymmetrical
(e.g. TGAC
and TGCT)
Short sequence Asymmetrical
(4-6 bp), often sequence of 5-7
palindromic
bp
Cleavage site
Non-specific >1000 bp Same as or
24-26 bp
from recognition site
close to
downstream of
recognition site recognition site
1. Restriction Enzymes
Restriction and Mutually exclusive
methylation
Separate
reactions
Simultaneous
ATP needed
for restriction
Yes
No
Yes
Mg 2+needed
for restriction
Yes
Yes
Yes
Commonly
used in
Random cutting and
fragments making
Gene cloning
Gene cloning
n
Maintenance of introduced DNA in the host and
transfer of the DNA to its progeny.
Tools of Recombinant DNA
Technology
Å
Å
Å
Å
In the year 1963, the two enzymes responsible for restricting
the growth to bacteriophage in E. coli were isolated. One of
these added methyl group to DNA, while the other cut
DNA. The latter was called restriction endonuclease.
The first restriction endonuclease, i.e. Hind II was isolated
by Smith Wilcox and Kelley in 1968.
Hind II always cut the DNA at specific base sequences, i.e.
of six base pairs. Apart from Hind II, more than
900 restriction enzymes have been isolated from over
230 strains of bacteria.
Protein
structure
Examples of Restriction Enzymes
Names
Sources
Sites
Types of End
Hpa I
Haemophilus
parainfluenzae
5 ′ GTT - AAC 3 ′
3 ′ CAA - TTG 5 ′
Blunt
Ssp I
Sphaerotilus
species
5 ′ AAT - ATT 3 ′
3 ′ TTA - TAA 5 ′
Blunt
Pst I
Providencia
stuartii
5 ′ CTGCA - G 3 ′
3 ′ G - ACGTC 5 ′
Sticky
Hind II
5 ′ GTC - GAC 3 ′
3 ′ CAG - CTG 5 ′
Blunt
Restriction enzymes belong to a larger class of enzymes
called nucleases, which are of the following two types
Haemophilus
influenzae
Eco RI
Escherichia coli
5 ′ G - AATTC 3 ′
3 ′ CTTAA - G 5 ′
Sticky
Hae III
Haemophilus
aegyptius
5 ′ GG - CC 3 ′
Blunt
Bam HI
Bacillus
amyloliquefaciens
5 ′ GGAT - CC3 ′
3 ′ CCTA - GG 5 ′
n
Å
Type I Enzyme
Naming of restriction enzyme proceeds in a way that the
first letter of the name comes from the genus and the
second two letters come from the species of prokaryotic
cell. Roman number following the names indicate the order
in which the enzyme were isolated from that strain of
bacteria, e.g. Eco RI comes from E. coli RY13.
n
Å
Features
Exonucleases, which remove nucleotides from the ends
of the DNA (either 5′ or 3′) in one strand of duplex.
Endonucleases make cuts at specific positions within
the DNA by inspecting the length of a DNA sequence.
Once finds its specific recognition sequence, it will bind
to the DNA and cut each of the two strands of the
double helix at specific points in their sugar phosphate
to backbones.
These restriction enzymes recognise a palindromic
nucleotide sequence in the DNA and cut both the strands
of DNA at that point. Palindrome in the DNA is a sequence
of base pairs that reads same on the two strands when
orientation of reading is kept the