SECTION-A
1. Define BOD. What does it indicate?
Ans. Biological Oxygen Demand. It indicates presence of sewage in water.
2. 20 parrots, 50 sparrows and 150 crows are found in one part of seven senses garden which has
large number of trees. Which parameter- species richness or species evenness can be easily
assessed from this information?
Ans. Species richness.
3. Why do farmers face the problems in Agro chemical based farming?
Ans. 1. Too expensive
2. Conventional breeding not able to increase production.
4. Give the meaning of Green revolution, White revolution, Blue revolution.
Ans. Green revolution - Crop production
White revolution - Milk production
Blue revolution - Fish production
5. What are the various sources of drugs?
Ans. Opioids, Cannabinoids, Cocaine, LSD.
6. If a given segment of a double stranded DNA has 30% thymine, whatpercentage of guanine and
adenine does this segment of DNA has respectively?
Ans. Guanine-20%, Adenine-30%
7. What do you mean by the term parthenogenesis? Explain with an example.
Ans. Sometimes the female gametes may develop into a new organism without fertilisation. In Rotifers,
honeybees-unfertilized eggs develop into adults.
8. Abingdon tortoise in Galapagos Island became extinct with in a decade after goatswere introduced
on the island. Why? What could be principle behind this situation?
Ans. Greater browsing efficiency of goat’s. Gause’s Competitive Exclusion Principle.
SECTION-B
9. Biomass is a more meaningful measure of population size. Explain with an example.
Ans. (i) Population large Total number is not an easily adoptable measure. Counting takes long time or
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practically impossible
(ii) There is no need to know the absolute population size for some investigations.
(iii) Number may sometimes be misleading e.g. In a given area there are 200Parthenium plants and a single
banyan tree. Here biomass size of the banyan tree is much more than those of 200 Parthenium plants.
10. Explain Downstreaming process.
Ans. It refers to the recovery and purification of biosynthetic products, particularly pharmaceuticals, from
natural sources such as animal or plant tissue or fermentation broth.
Stages in Downstream Processing
A widely recognized heuristic for categorizing downstream processing operations divides them into four
groups which are applied in order to bring a product from its natural state as a component of a tissue, cell or
fermentation broth through progressive improvements in purity and concentration.
11. If total number of base pair is multiplied with distance between two consecutive bases,length of
DNA comes out to be appropriate 2.2 m. How is the packaging of DNA helix done in a tiny nucleus of
dimensions of approximately 10-6 m?
Ans. Negatively charged DNA is wrapped around positively changed histone protein octamer to form
nucleosome each containing 200 bp. Nucleosomes are the reapting units of chromatin which are packed to
form chromatin fibers which are further coiled & condensed to form chromosome.
12. What is ecosan?
Ans. Ecological sanitation (Ecosan): A sustainable system for handling humanexcreta without using water
but with composting method.
Advantages of ecosan:
(a) Wastage of water is reduced
(b) Practical and efficient
(c) Hygienic and cheap
(d) Excreta can be recycled and used as natural fertilizer.
13. Conservation of bio-diversity is a collective responsibility of all nations. Mention the steps taken
by various countries in this direction.
Ans. Earth Summit held at Rio de Janerio and World Summit on sustainable development held in 2002
in Johannesburg South Africa where 190 countries pledged their commitment to achieve by 2010, a
significant reduction in the current rate of biodiversity loss at global, regional and local levels.
14. Describe pond as an ecosystem.
Ans. Pond has biotic and abiotic components
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a) Biotic – Phytoplankton ,Zooplankton , small fishes , large fishes , frogs , snake ,etc.
b) Abiotic - water , dissolved organic and inorganic substances ,sunlight , temp . Phytoplankton (microscopic
plants ) – producers . Zooplankton (microscopic animals ) – primary consumers Small fishes - secondary
consumers Large fishes , frog, snails – tertiary consumers.
15. What is interference competition? Define competitive exclusion principles.
Ans. (i) Feeding efficiency may be reduced due to interference of another species. E.g. –Tiger and deer.
(ii)Two closely related species need same resource can not co-exist indefinitely.
16. Shoib Akthar is very much particular about his performance. Recently he was medically unfit and
was not allowed to play the match. What went wrong and what do the sportspersons do to enhance
their performance?
Ans. Detection of banned drugs in a blood test. Steroids are used to temporarily enhance the performance.
They misuse narcotic analgesic, anabolic steroids, diuretics and certain hormones to increase muscle
strength.
17. What are plasmids?
Ans. Plasmids are the most commonly used vector system. Several types available for cloning of foreign
DNA in the host organism Escherichia coli. Many E. coli plasmids allow the expression of proteins encoded
by the cloned DNA.
18. What do you understand by the term infertility?
Ans. Infertility when a couple fails to conceive after one year of sexual life withoutcontraception. 80% of all
women desiring children, conceive within 1 year of marriage and another 10% within the second year.
According to the World Health Organisation, incidence of infertility is about 10 % worldwide. Another 1012% of all the other couples have only one child and wish to have more. The incidence of infertility is
gradually increasing all over the world.
SECTION-C
19. What are the post-fertilisation changes?
Ans. POST FERTILISATION CHANGES:
STAGES OF EMBRYO DEVELOPMENT AFTER FERTILISATION:
1. Zygote divides by mitosis into suspensor & embryo cells
2. Suspensor cell forms a globular basal cell which remains embedded in the endosperm & a multicellular
suspensor bearing the embryo
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3. Globular embryo becomes heart-shaped & then grows into mature embryo with radicle, plumule &
Cotyledons
Primary endosperm nucleus – divides repeatedly to form endosperm, food for the embryo. Further ature
ovary becomes fruit and mature ovule becomes seed.
20. Explain the term OUTBREEDING DEVICES.
Ans. Continuation of self-pollination results in breeding depression. Flowering plants have developed
many devices to discourage self-pollination & encourage cross-pollination these are:
(i) Bearing unisexual flowers
(ii) Anther & stigma mature at different times
(iii) Anther & stigma placed at different positions
(iv) Self-incompatibility where pollen grains of a flower do not germinate on the stigma of the same flower
21. Define the terms:
(i) Stabilising Selection
(ii) Directional Selection
Ans. (i) Stabilizing selection favours the norm, the common, average traits in a population .In nature,
natural selection is most commonly stabilizing. The average members of the population, with intermediate
body sizes, have higher fitness than the extremes. Stabilizing selection culls extreme variants from the
populations.
(ii) Directional selection shifts the overall makeup of the population by favoring variants of one extreme
within a population. Natural selection may be directional: it may favor, for example, smaller individuals and
will, if the character is inherited, produce a decrease in average body size. Directional selection could, of
course, also produce an evolutionary increase in body size if larger individuals had higher fitness.
22. In snapdragon species a plants with red flowers are crossed with a plant with white flowers.
Phenotype different from the parents in obtained in F1 generation. Why? Write scientific name of this
plants and also genotypic ratio obtained in F2 generation.
Ans. Red flowers with White flowers
RR x r r-gametes
Rr
Pink flower-progeny
selfing
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Rr x Rr-Gametes
Progeny
Red: Pink: white
RR: Rr : rr
1: 2: 1
This is due to incomplete dominance. In this phenomenon neither of the two alleles of a gene is completely
dominant over the other.
Antirrhinum majus
Genotypic ratio 1: 2: 1
RR:Rr:rr
23. Describe the parts of female reproductive system.
Ans. Ovary:
(i) Each ovary contains immature ova (eggs) in follicles
Fallopian tubes
(i) Two thin tubes attached to the upper sides of uterus tubes.
Uterus:
(i) Pear-shaped organ located in lower abdomen
Vagina: Birth canal:
(i) Menstrual blood leaves the body
(ii) Organ of intercourse
Cervix:
(i) Located at inner end of vagina
(ii) Opening of uterus into vagina
25. What is artificial hybridisation?
Ans. ARTIFICIAL HYBRIDISATION: Types of cross-pollination performed by man for crop improvement. It
is achieved by
(i) Emasculation i.e. removal of anthers from the flower bud of a bisexual flower before the anther dehisces
using a pair of forceps
(ii) Bagging i.e. covering the emasculated flowers with a bag of suitable size to protect them from
contamination with unwanted pollen
If flower is unisexual, emasculation is not needed. Flower bud is bagged & once the stigma becomes
receptive, pollination is done using desired pollen & the flower is rebagged.
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26. What is the difference b/w endometrium and myometrium?
Ans.
Endometrium
Myometrium
It is innermost glandular layer that It is the middle thick layer of smooth
lines the uterine cavity
muscles of the uterine wall.
Implantation occurs in this layer
It is responsible for the uterine
movement.
It undergo cyclic changes during
the menstrual cycle
It does not undergo any cyclic
changes during the menstrual cycle
27. Explain the process of tissue culture in details.
Ans. Tissue culture- cultured with any plant part called explant.
Types –
1. Meristem Culture –When apical part is taken and cultured. Uses: a)Rapid clonal multiplication
b)Production of virus free plants c)Production of transgenic plants d)Germplasm collection
2. Protoplast culture and somatic hybridization- The plant cell lacking cell wall is protoplast. Fusion of
protoplast is done by Polyethylene glycol. Pomato is somatic hybrid of potato and tomato.
3. Micropropagation-Tissue culture technique used for rapid vegetative propagation of ornamental plants
and fruit trees
4.Somaclone-Plants obtained from single plants by vegetative propagation.
SECTION-D
28. Explain the term multiple alleles.
Ans. Although any individual has at most two different alleles, most genes exist in a large number of allelic
forms in the population as a whole. In some cases, the alleles have different effects on the phenotype, and
their dominance interactions with each other can be described as a series. For example, the best known
human blood groups, the ABO system comprises three sets of alleles at the I locus, IA, IB, and IO. The first
two are dominant to the latter: that is, the AA and AO genotypes produce indistinguishable blood group
phenotypes, called "Type A", as do BB and BO, which produce "Type B"
Blood, see the details in the diagram given below:
Allele from
Parent 1
IA
IA
Allele from
Parent 2
IA
IB
IA
i
B
I
IA
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Genotype of
offspring
Blood types of
offspring
IA IB
IA IB
A
AB
IA i
IA IB
A
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IB
IB
IB
i
IB IB
IB i
B
B
i
i
ii
O
29. Name few common STD’s with their symptons.
Ans. Human Papilloma Virus: Thought to be one of the main causes of cervical cancer. Has been linked
with other types of cancers of female reproductive system. HPV can be treated to reduce signs and
symptoms. Currently no cure for this virus. HPV vaccine recently developed to prevent HPV infection.
Herpes Virus: STD that presently with no cure. Treatment available. Home remedies & natural treatment
available. Herpes symptoms include blisters or sores that periodically break out on the genitals.
Hepatitis: To cure for those already infected, a Hepatitis B (HBV) vaccine available to prevent spread of this
infection. Many are asymptomatic, however those who do suffer from Hepatitis B symptoms may have many
unpleasant discomforts. Infection may clear up on its own. Some people may suffer from chronic infections
for many years. Treatment available for chronic sufferers. Other types of hepatitis infections that can be
passed through sexual contact include Hepatitis A and Hepatitis C.
HIV/AIDS: Most dreaded STD. New ways of treating this infection significantly prolongs an infected person''s
life. For many this infection eventually progresses to AIDS and, ulitmately, death. More than 40 million
people worldwide are infected with the HIV virus; women account for 50% of those infected.
Syphilis: Throughout history, cases of syphilis have been recorded. Can easily be treated and cured.
Without treatment, syphilis symptoms can progress and affect the nervous system and brain leading to
dementia and even death.
Trichomoniasis: most common, curable STDs. However, symptoms may be mistaken for a yeast infection
causing women to use wrong type of treatment for her vaginal discharge.
Common Infections:Chlamydia and gonorrhea often infect a person at the same time. Although the
symptoms of chlamydia are different from gonorrhea not unusual for person to be asymptomatic. If testing
for chlamydia, good idea to test for gonorrhea. Both STDs can be cured but can damage reproductive
system if left untreated.
Pubic Lice: Crabs are very similar to head lice. Itchy symptoms can be hard to miss. Treatment for pubic
lice can easily take care of the discomfort these pests can cause.
Rare Infections: Granuloma inguinale and chancroid,. Other lesser-talked about STDs include
nongonococcal urethritis and molluscum contagiosum.
30. Draw a neat and well labelled diagrma of human sperm.
Ans.
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SECTION-A
1. Why is internal fertilisation considered to be more advanced method than external fertilisation?
Ans. Internal fertilisation ensures more chances of fertilisation with less wastage of gametes.
2. Which category of bacteria is used in production of bio-gas?
Ans. Methanogens
3. What is hirudin? How do you get it?
Ans. Anti coagulant. Obtained from transgenic brassica napus.
4. Body has a large reservoir of erythrocytes. Is it a passive or active store house? Validate your
answer?
Ans. Spleen. It acts as the filter of the blood by trapping blood borne micro-organism.
5. What is the principle of biotechnology?
Ans. Its principle is genetic engineering.
6. What is standing crop?
Ans. The living matter at a given trophic level at present time is called standing crop.
7. Name a scientist who proposed that species richness increases with increased explored area but
only up to a limit. What is the shape of a graph if species richness is plotted against area for a wide
variety of taxa.
Ans. Alexander von Humbolt / Rectangular hyperbola which on log scale appears as linear straight line.
8. Which act came into force in India in 1981?
Ans. Air (Prevention and control of pollution) act
SECTION-B
9. Biodiversity decreases as one move from equator towards pole. Justify this statement with a
suitable example.
Ans. Equator has tropical environment and hence harbour more species e.g. Columbia near the equator has
1400 species of birds , while New York at 410 N has 105 Species.
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10. Why the length of a food chain in an ecosystem is generally limited to 3--4 trophic levels ?
Ans. According to 10% law, 90% of energy is lost when it moves from trophic level to the next the residual
energy decreases drastically with 2-3 trophic levels. That is why a food chain in an ecosystem is generally
limited to 3-4 trophic levels.
11. What is vaccination?How does it help in producing immunity?
Ans. Vaccination is the process of introducing a preparation of antigenic protein of the pathogens or
weakened or killed pathogen into the body. -The vaccines include quick multiplication of B and Tlymphocytes;some of them are stored as memory cells -The B-lymphocytes quickly produced
antibodies,which neutralize the antigen during infection.
12. What are the rules of segregation and independent assortment?
Ans. Rule of segregation (Separation): Gametes (sex cells) only receive one allele from the original gene.
Rule of Independent assortment: One trait will not determine the random selection of another. Incomplete
dominance: When one allele of a gene is not completely dominant over the other and the
F1 hybrids are intermediate between two parents. The phenotypic and genotypic ratio is same.1:2:1 in F2
generation. E.g. Snapdragon orAntirrhinum majus.
13. What is indicated by a cross section of earth’s crust? Name the evolutionary evidence in which
different aged rock sediments containing fossil of life form are examined.
Ans. (i) Arrangement of sediments as layers one over the other during the long history of earth.
(ii) Pale-ontological evidence.
14. It is estimated that more than 70% of the world livestock population is in India and China. Yet
they contribute only 25% of the world’s farm produce. What does it indicates. How can we improve
it?
Ans. The per unit productivity is very low. So in addition to conventional practice ofanimal breeding & care,
new technologies also have to be an applied.
15. What are cloning vectors?
Ans. Cloning vectors are extra-chromosomal ''replicons'' of DNA which can be isolated and can replicate
independently of the chromosome. Vectors usually contain aselectable marker - a gene that allows
selection of cells carrying the vector e.g. by conferring resistance to a toxin. DNA of interest can be cloned
into the vector and replicated in host cells, usually one which has been well characterised.
16. What are the advantages of CNG?
Ans. Advantages of CNG:-
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(a) CNG burns most efficiently.
(b) Cheaper Cannot be siphoned.
(c) Cannot be adulterated.
17. Ecologists believe that communities with more species tend to be more stable than those with
less species. What attributes are taken into account while defining a stable community. Mention the
observation of David Tilman ecological experiments using outdoor plots.
Ans. Less variation in productivity from years to years, resilient to occasional disturbances, resistant to
invasions by alien species. Tilman found that plots with more species showed less year to year variations in
total biomass & increased diversity contributed to higher productivity.
18. Arrange the following terms in a correct developmental sequence Pollengrain ,sporogenous
tissue , microspore tetroid , pollen mother cell male gametes ?
Ans. (i) sporogenous tissue
(ii) pollen mother cell
(iii) microspore tetrod
(iv) pollen grain 1
(v) male gamete
SECTION-C
19. Differentiate b/w genotype and phenotype.
Ans.
GENOTYPE
PHENOTYPE
Genotype remains the same
Phenotype may change with time
throughout the life of an individual. and environment, e.g. infant.
Genotype cannot be studied
Phenotype can be known through
directly. It can be known through the direct observation.
study of ancestor, mating and
offspring.
In a given environment or time,
Individuals with similar phenotypes
individual with similar genotype will may not belong to same genotype.
produce similar character.
20. Describe Macrosporogenesis in detail.
Ans. MEGASPOROGENESIS
Megaspore mother cell (2n) undergo Meiosis, giving 4 Megaspores (n) (3 megaspores degenerate, 1
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remains functional)
Funtional Megaspore (n) divides 3 times by mitosis and then 8 Nucleated Embryo Sac formed, which
gives 3 cells group at micropylar end out of that one of them is the egg cell(n) & 2 synergids (n) and further
at the chalazal end cell called antipodals(n) 2 polar nuclei at center(n each ) are formed.
21. Give details of external genetilia of female reproductive system.
Ans. Labia:
(i) 2 layers of skin, which fold over the opening to vagina and urethra
(ii) Inner labia (labia minora)
(iii)Outer labia (labia majora) 1.Two folds of skin, surround vaginal area 2. Pubic hair grows on outer labia
Clitoris:
(i) Small organ, 5 to 10 millimeters long
(ii) Located at junction of inner labia near front of body
(iii) Contains erectile tissue & sexually sensitive
Mons pubis : Cushion like fatty tissue covered by skin and pubic hair
22. What is transforming principle? Explain with Griffith’s experiment.
Ans. Transformation experiment or Griffith effect.
• Griffith performed his experiments on Mice using Diplococcus pneumoniae.
• Two strains of bacteria are S-type and R-type cells.
• Experiments : Living S-strain Injected into mice →Mice killed
Living R-strain Injected into mice → Mice lived
Heat Killed S-strain Injected into mice → Mice lived
Living R-strain + Heat Killed S-strain Injected into mice → Mice killed
# Grffith concluded that R type bacteria is transformed into virulent form.
# Transformation is the change in the genetic constitution of an organism by picking up genes present in the
remains of its relatives.
23. “Allele frequencies in a population are stable and are constant from generation to generations”.
Who proposed this principle. State the factors that are known to affect it, How these five factors
mentioned can cause a change in a frequency of alleles of a population?
Ans. Hardy –Weinberg proposed this principle.
Factors affecting it areGene migration, genetic drift, mutation, genetic recombination & natural selection.
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Variation due to mutation or recombination during gametogenesis or due to gene flow or genetic drift results
in changed frequency of genes & alleles in future generation. Coupled to enhanced reproductive success,
natural selection makes it look like different population
24. What are the steps to plant breeding?
Ans. Steps in Plant breeding:1. Collection of variability-Collection and preservation of all different wild varieties, species, relatives of
cultivated species etc. are also called germplasm collection.
2. Evaluation and selection of parents-Germplasm is evaluated to identify plants with desirable traits.
3. Cross hybridization among the selected parents-Two plants having two desired characters are
hybridized to get new hybrid having two desired characters.
4. Selection and testing of superior recombinants-Selection of the plants having desired character
combinations.
5. Testing,release and commercialization of new cultivars-Newly selected lines are evaluated for their
yield, agronomic traits, disease resistance etc. and released into the market.
25. What are the characteristics of DNA vectors?
Ans. 1. Origin of replication (ORI: This process marks autonomous replication in vector. ORI is a specific
sequence of nucleotide in DNA from where replication starts. When foreign DNA is linked to this sequence
then along with vector replication, foreign (desirable) DNA also starts replicating within host cell.
Selectable Marker
2. Charecteristics of Selectable marker: A gene whose expression allows one to identify cells that have
been transforrned or transfected with a vector containing the marker gene. A marker gene is used to
determine if a piece of DNA has been successfully inserted into the host organism.. A gene, usually
encoding resistance to an antibiotic,.A selectable marker will protect the organism from a selective
agentthat would normally kill it or prevent its growth.
3. Restriction site: It should have restriction sites, to allow cleavage of specific sequence by specific
Restriction Endonuclease. Restriction sites in E.coli cloning vector pBR322 include HindIII , EcoRI , BamHI ,
SalI, PvuI, PstI, ClaI etc.
26. Biomass is a more meaningful measure of population size. Explain with an example.
Ans. (i) Population large Total number is not an easily adoptable measure. Counting takes long time or
practically impossible
(ii) There is no need to know the absolute population size for some investigations.
(iii) Number may sometimes be misleading e.g. In a given area there are 200Parthenium plants and a single
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banyan tree. Here biomass size of the banyan tree is much more than those of 200 Parthenium plants.
27. What are the causes of biodiversity loss?
Ans. Major causes of biodiversity loss:
(i) Habitat loss and fragmentation
(ii) Over exploitation
(iii) Alien species invasions
(iv) Co-extinctions and mass extinctions, ,
(v) Overexploitation ,
(vi) Urbanization
(vii) Pollution
(viii) Global climate change
SECTION-D
28. What are the different patterns of biodiversity?
Ans. 1) Latitudinal gradients – Generally, species diversity decreases, as we move from equator to
poles.e.g. However , Tropics(23.50N -23.50S) show richest species diversity. Speciation is generally a
function of time. Temperate region is subjected to glaciation. Tropical regions remained relatively
undisturbed for millions of years and thus had a long evolutionary time for species diversification. Moreover,
tropical environments are less seasonal, relatively more constant and predictable. Such constant
environment facilitates niche specialization and lead to greater species diversity. Tropical latitudes also get
huge solar radiations which promotes higher productivity.
2) Species - Area Relationship: ALEXANDER VON HUMBOLDT observed within a region species
richness increased with increasing explored area but only up to a limit. The relation between species
richness and area for a wide variety of taxa turns out to be a rectangular hyperbola. On a logarithmic scale
the relationship is a straight line describe by the equation LogS = logC +Z log A Where S= species
richness, A = Area, Z = slope of the line(regression coefficient),C = Y- intercept. It has been noted that
regardless of the taxonomic group or region the slope of the regression line are amazingly similar.
However, for a very large area like the entire continent theslope of the line is steeper.
29. Describe male reproductive system.
Ans. The Male reproductive system
1. Penis
a. Urination
b. Sexual intercourse
1. Corpus cavernosum- spongy tissue that fills with blood to make penis erect
2. Glans- the head, end of penis
3. Foreskin
i. Covers glans,
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ii. May be removed surgically in an operation (circumcision)
2. Scrotum
a. Located behind penis
b. Contains two testes
c. Temperature sensitive (Sperm must be made in cooler conditions i.e, 2-3 C lower than body temperature)
3. Testes
a. Sperm is produced by the seminiferous tubules due to FSH
b. Testosterone is produced by Leydig cells due to LH
1. Causes the development of the male sex organs at ~8 weeks after conception.
2. Responsible for facial, armpit, and pubic hair, bone growth and muscular development.
c. Testes formed in the abdomen before birth. Descend through the "inguinal canal" during fetal or post-natal
life. Sometimes it may take months/years to reach right place. Possible site for hernia.
4. Epididymis:
Stores sperm until they have matured.
5. Vas deferens:
Tube that leads from the epididymis to the urethra. Many sperm cells are stored here too.
6. Prostate gland:
Provides an alkaline fluid that can protect sperm from harsh vaginal acids.
7. Seminal Vesicles:
Produce food for sperm. Food "Fructose"
8. Cowper''s gland:
Produces clear lubricating fluid.
30. What are the few problems related to the adults? And what measures govt has taken to overcome
it?
Ans. Adolescence Reproductive and Sexual Health (ARSH) topics are to be taken care of to dispel the
myths and misconception about this important aspect with focus on: reducing risky behavior
Theories which explain what influences people''s sexual choices and behaviour reinforced message about
sexual behaviour and risk reduction
Providing accurate information about, the risks associated with sexual activity, about contraception birth
control, methods of avoiding or deferring intercourse
Dealing with peer and other social pressures on young people; providing opportunities to practice
communication, negotiation and assertion skills.
Uses a variety of approaches to teaching and learning that involve and engage young people and help
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them to personalise the information.
Uses approaches to teaching and learning which are appropriate to young people''s age, experience and
cultural background.
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SECTION-A
1. What is the special asexual reproductive structure in Chlamydomonas?
Ans. Zoospores
2. What is the function of FIMBRIAE in fallopian tubes?
Ans. "Fimbriae" are finger-like structures on the end of each tube,which helps in the collection of the
ovum after ovulation.
3. Which tissue located inside the ovarian cavity?
Ans. Placenta
4. Mendel followed a definite sequence of steps in making a cross between tall and dwarf pea plants to
study the inheritance of one gene. Mention them in proper order.
Ans. Plant tall and dwarf -removal of anthers [emasculation] from one -transfer of pollen from second to first
(pollination) - Syngamy - Seed production - Formation of pod.
5. Give salient features of the two strands of DNA.
Ans. Two chains are complementary to each other. Two chains are held together byhydrogen bond. AdenineThymine pair has two hydrogen bonds. Guanine-Cytosine pair has three hydrogen bonds.
6. A farmer in order to continue and enhance the benefits used to cross the siblings of the
domesticated cattle from his reserves. This he was doing for the past few generations. He was
surprised to notice that the breed which used to give him good returns has reduced itsproductivity.’
What does this tells you about the exploitation of scientific tech. Was he going wrong some where or
there was some other reason for reduced profits?
Ans. Continued inbreeding – accumulation of homozygotes- inbreeding depression – loss of productivity.
7. Which strain of yeast is used for production of swiss cheese?
Ans. Propionibacterium sharmanii.
8. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves. What is the
reason behind it?
Ans. Cry protein of bt toxin in Bacillus thuringiensis is produced in an inactive state (pro-toxin). It remains
inactive until subjected to alkaline pH.
SECTION-B
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9. Explain the female reproductive part.
Ans. GYNOECIUM / CARPEL (THE FEMALE REPRODUUCTIVE ORGAN) : Each Carpel consists of ovary,
style & stigma. Ovules are attached to ovary by placenta. The funicle is the stalk of ovule Hilum, a region
where funicle is attached , Integuments which cover embryo sac. Micropyle – a pore for entry of pollen tube &
to imbibe water.
10. What is emergency oral contraceptive?
Ans. Emergency Oral Contraception After unprotected sex, emergency oralcontraception can prevent
pregnancy. Sometimes called postcoital or morning after ‘contraception. Mainly stops ovulation. Regular use
of emergency contraceptives has serious health hazards. Eg is i-pill.
11. Give details of DNA packaging.
Ans. DNA of eukaryotes is wrapped around positively charged histone proteins to form nucleosome.
Nucleosome contains 200 base pairs of DNA helix.
Histone octamer =2(H2a+H2b+H3+H4) Linker DNA bears H1 protein # Chromatin fibres formed by
repeated units of nucleosomes.
Non histone proteins required for packaging. Regions of chromatin, loosely packed and stains lightly is
called euchromatin. Regions of chromatin, densely packed and stains darkly is called heterochromatin.
12. (a) Name the respective forms in which the malarial parasite gains entry into
(i) Human body and (ii) Body of female Anopheles
(b) Name the hosts where the sexual and the asexual reproduction of malarial parasite occur
respectively
(c) Name the toxin responsible for the appearance of symptoms of malaria in humans.Why do these
symptoms occur periodically ?
Ans. (a) (i)-Sporozoite (ii)-Gametocyte
(b) -sexual reproduction in mosquito -asexual reproduction in human body.
(c) Haemozoin - Haemozoin is released when the RBCs rupture and release the pathogen -some cells of
pathogen enter fresh RBCs and reproduce asexually and repeat the cycle; hence the symptoms appear
periodically.
13. A patient who has been suffering from myocardial infarction is found to be having clots in the
blood vessels. “Clot Buster” is used to dissolve the clots. Name the clot buster used to digest the clot
and the micro-organism from which it is extracted also.
Ans. (i) “Clot buster”- an enzyme Streptokinase
(ii) micro-organism-A bacterium – Streptococcus
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14. What are the potential risks of using GM food?
Ans. Potential risks(i) Products of transgene - allergic or toxic
(ii) Cause damage to natural environment
(iii) Weeds also become resistant
(iv) Can endanger native species
15. What is convergent evolution?
Ans. Convergent evolution takes place when species of different ancestry begin to share analogous traits
because of a shared environment or other selection pressure. For example, whales and fish have some similar
characteristics since both had to evolve methods of moving through the same medium that is water.
16. What is co-dominance?
Ans. Co-dominance occurs when the contributions of both alleles are visible in the phenotype. In
the ABO example, the IA and IB allele classes are co-dominant in producing the AB blood group phenotype, in
which both A-type and B-type antigens are made. A third allele class, IO, produces no antigens and
is recessive to both the others.
17. What are the objectives of animal breeding?
Ans. Animal Breeding-objectives:
1. Improved growth rate.
2. Increased production
3. Improve Desirable Qualities.
4. Improved resistance to diseases
5. Improved resistance to adverse environmental conditions.
18. How can a cell having 12 chromosomes produce two daughter cells, each with 12 chromosomes?
Ans. During asexual reproduction, each chromosome replicates. If the parent cell has 12 chromosomes, after
replication it has 24. When the cytoplasm divides, these 24 chromosomes are distributed equally so that each
daughter cell has 12 chromosomes.
SECTION-C
19. What are the three basic steps towards genetically modified organisms?
Ans. These are:
(i) Identification of DNA with desirable genes
(ii) Introduction of the identified DNA into the host
(iii) Manintenance of introduced Dna in the host and transfer of the DNA to its progeny
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20. Name and explain the kind of interaction in the following:
1. Algae and Fungi in Lichens
2. Head Louse Humans
3. Hermit Crab and Sea Anemone
Ans. 1. Algae and Fungi in Lichen: Interaction of mutualism where the two species are equally benefited.
Fungus provides protection, helps in absorption of water and minerals, Algae provide food for the Fungus.
2. Head Louse Human: This is case of Parasitism where the louse is an ectoparasite. Parasite takes shelter on
humans and also derives nutrition.
3. Hermit Crab and Sea Anemone: It is commensalisms where one species is benefited and the other is
neither benefited nor affected. Sea Anemone is benefited as it does not have to move to places rich in
nutrients, while hermit crab is neither benefited nor harmed.
21. During a visit, students found that a forest has been destroyed totally by fire.The students asked
their teacher, “Can the forest grow here again?” The teacher explained,” Yes, of course. Even a bare
rock in course of time can also convert into a forest. Growth of forest on a bare rock is known as
primary succession while community developed in the burnt forest is known secondary succession. “
Now answer the following ----(i) In your opinion, where will be the growth of community faster ---the burnt forest or the bare rock?
Why?
(ii) Why on bare rock succession is called primary while in a burnt forest, succession is secondary?
Ans. (A) Ecological succession on a burnt forest will be faster due to --(i) Presence of soil & organic matter.
(ii) Presence of seeds & spores beneath the soil.
(iii) Remains of previous flora like roots, underground stem etc.
(B) Ecological succession on bare rock is known as primary succession because there were no previous flora /
fauna, while secondary succession developed after the destruction of previous flora.
22. What are restriction type-II enzymes?
Ans. Type II enzymes are those used in the vast majority of molecular biology techniques. Many are now
commercially available.
Many Type II restriction endonucleases recognise PALINDROMIC sequences (From Greek
palindromos, running back again, recurring : palin, again)
A segment of double-stranded DNA in which the nucleotide sequence of one strand reads in reverse order
to that of the complementary strand. (always read from the same direction)
For example, EcoRI recognises the sequence
5''-G A A T T C-3''
3''-C T T A A G-5''
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23. Differentiate b/w tubectomy and vasectomy.
Ans.
Tubectomy
Vasectomy
Method of sterilisaion in females
Method of sterilization in males
Fallopian tubes of both sides are cut and tied.
Vas deference is cut and tied.
It prevents ova to reach the place of fertilization. It prevents sperms to reach the place of fertilization.
24. What is Double fertilization? Why it is called so? Elaborate the term Syngamy?
Ans. Fertilization: Pollen grains germinate on stigma & pollen tube grows through style. This pollen tube
reaches micropyle & releases two male gametes into embryo-sac. Fertilisation is the process of fusion of male
& female gametes (n+n) to form a diploid(2n) zygote.
SYNGAMY: Fusion of one male gamete(n) with egg (n) so that Zygote(2n) is produced
First Fusion is of two Polar Nuclei(n+n=2n)
Second Fusion is of Male Gamete which Fuses with the fusion product of the two polar nuclei(3n)
Third Fusion fusion of male gamete with egg cell.
DOUBLE FERTILIZATION: In an embryo sac, two type of fusions are seen,i)Fusion of male gamete with egg –
First fertilisation, ii)Fusion of fusion product of polar nuclei with male gamete-Second Fertilisation. Hence there
are two Fertilizations occurring hence this phenomenon is known as double fertilization.
25. Explain in details the process of STP.
Ans. Treatment is done in two stages.
Primary : Physical removal of particles large and small by filtration and sedimentation. Solids so left makes
primary sludge and the Supernatant becomes effluent.
Secondary: Primary effluent taken to large aeration tanks. Agitated mechanically and air pumped into it.
Aerobic microbes form masses with fungal filaments known as flocs.
Microbes consume organic matter in effluent for growth, thus BOD ( Biological oxygen demand) reduced.
Then it is passed into settling tank.
Bacterial flocs get sedimented , a small portion is kept to activate the sludge. Small part of activated sludge
used as inoculums in aeration tank and major part is pumped into large anaerobic sludge digesters
Anaerobic bacteria digest bacteria and fungi. Bacteria produce gases such as menthane, hydrogen sulphide
and CO2 – Biogas. And then secondary effluent is released into rivers and streams.
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26. What are the two keys to Darwinain theory of natural selection?
Ans. Branching descent and natural selection are the two key concepts of Darwinian Theory of evolution.
According to him all the species inhabiting earth today descended from ancestral species (descent with
modification)and natural selection is the mechanism for such descent with modification. Natural Selection
states that a population of organisms can change over the generations if individuals having certain heritable
traits leave more offspring than other individuals, resulting in a change in the populations genetic composition
over time.
27. “Fertilisation leads to the formation of an embryo”. On the basis of this statement answer the
following questions:
i. Give the technical term for the development of an embryo.
ii. What are the events that occur during embryo development?
iii. The development of a zygote depends on two factors. What are they?
iv. How will you categorise animals based on the development of a zygote inside or outside the female
body?
Ans. i. Embryogenesis.
ii. The two important events are cell division and cell differentiation. Cell divisions increase the number of cells
in the developing embryo while cell differentiation helps group of cells to undergoes certain modifications to
form specialised tissues and organs to form an organism.
iii. The development of the zygote depends on : The type of life cycle of the organism and the environmental
exposure of an organism.
iv. In external fertilisation, zygote is formed in the external medium (usually water), whereas in those exhibiting
internal fertilisation, zygote is formed inside the body of the organism.
SECTION-D
28. What are the accessory glands associated with male reproductive system?
Ans. Accessory glands
Three accessory glands provide fluids that lubricate the duct system and nourish the sperm cells. They are the
seminal vesicles, the prostate gland, and the bulbourethral glands (Cowper glands).
Seminal vesicles
Seminal vesicles are sac-like structures attached to the vas deferens at one side of the bladder. They produce
a sticky, yellowish fluid that contains fructose. This fluid provides sperm cells energy and aids in their motility.
Prostate gland
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The prostate gland surrounds the ejaculatory ducts at the base of the urethra, just below the bladder. The
prostate gland is responsible for the production of semen, a liquid mixture of sperm cells, prostate fluid and
seminal fluid.
Bulbourethral glands
The bulbourethral glands, also called Cowper glands, are two small glands located on the sides of the urethra
just below the prostate gland. These glands produce a clear, slippery fluid that empties directly into the urethra.
It produces substances related to nourishment of spermatozoa.
29. Explain Mendel’s breeding cross.
Ans. 1. Pure breeding parents for a pair of contrasting character (allelic Pair) is taken
e.g, Tall pure-bred pea plants (TT) & short pure-bred pea plants (tt)
2. Gamete formation (Meiosis)
3. Hybridization (crossing is done)
4. F1 generation - the product of the above cross (are called hybrids)
5. Selfing (allowed to self fertilize / self breeding )
6. Gamete formation (Meiosis)
7. F2 generation - the product of the above selfing
8. Analysis of result (Phenotype and Genotype)
30. Explain r-DNA technology.
Ans. Recombinant DNA technology:
An organism''s genome contains virtually all the information necessary for its growth and development
Steps in producing recombinant DNA
1. The required gene is cut from a DNA molecule using a restriction enzyme.
2. A bacterial plasmid is isolated and cut with the same restriction enzyme. This ensures cut ends are
complementary (same base sequence) to the ends of the required gene.
3. The required gene is joined to the plasmid using the enzyme DNA ligase in a process called ligation.
4. The resulting recombinant plasmid is returned to the bacterial cell.
5. The bacteria reproduce and the required gene is cloned.
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SECTION-A
1. What is emergency oral contraceptive?
Ans. Emergency Oral Contraception After unprotected sex, emergency oralcontraception can prevent
pregnancy. Sometimes called postcoital or morning after ‘contraception. Mainly stops ovulation. Regular
use of emergency contraceptives has serious health hazards. Eg is i-pill.
2. Explain the process of MICROSPOROGENESIS.
Ans. MICROSPOROGENESIS: It is the process of formation of pollen grains. Microspore mother cell (2n),
undergoes meiosis which gives microspore (n), and then this undergoes mitosis and gives pollen grains(n).
3. Give mechanism of action of type-I restriction enzymes.
Ans. Type I Recognise specific sequences but then track along DNA (~1000-5000 bases) before cutting one
of the strands and releasing a number of nucleotides (~75) where the cut is made. A second molecule of the
endonuclease is required to cut the 2nd strand of the DNA e.g. EcoK.
4. Define the term life span.
Ans. The period between birth and the natural death of an organism is called its life span.
5. Give salient features of the two strands of DNA.
Ans. Two chains are complementary to each other. Two chains are held together byhydrogen bond.
Adenine-Thymine pair has two hydrogen bonds. Guanine-Cytosine pair has three hydrogen bonds.
6. Is evolution a process or the result of a process? Name the two key concepts of Darwinian Theory
of evolution.
Ans. When we describe the story of this world, evolution is described as a process. If we describe the story
of life on earth, we treat evolution as a consequence of a processcalled natural selection. Hence till the day it
is not clear.
7. As the population is continuously increasing and land for agriculture is decreasing. So how we
can overcome food scarcity problem. Suggest two measures.
Ans. Sea food fisheries
Use DNA modulation technique for better prospects in agriculture.
8. How do you think microorganisms are a foe to humans? What medical terminology has been
suggested for such organisms?
Ans. Microbes Cause several kind of diseases. Pathogens / disease causing microorganisms.
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SECTION-B
9. Explain MOET in detail.
Ans. MOET- This is a technique for herd improvement. Hormones(FSH) are given to the cow for inducing
follicular maturation and super ovulation. The cow is either mated with best bull or inseminated. It is done in
cattle, sheep, rabbits etc.
10. What is central dogma of life and who proposed it?
Ans. It was Proposed by F.Crick, it states that genetic information flows from DNA-RNA-Protein.
11. What similarities do you find in seed bank and pollen bank? Write their importance.
Ans. Pollen grain of different species of plants can be stored for years in liquid nitrogen (196ºC) like seeds.
Such type of storage is called pollen banks similar to seed banks, in crop breeding programme.
12. What are the three basic steps towards genetically modified organisms?
Ans. These are:
(i) Identification of DNA with desirable genes
(ii) Introduction of the identified DNA into the host
(iii) Manintenance of introduced Dna in the host and transfer of the DNA to its progeny
13. What are the advantages of people being healthy ?
Ans. When people are healthy,
(a) They are efficient at work which consequently increases productivity and brings economic prosperity
(b) Health increases longevity.
(c) It reduces infant and maternal mortality.
14. Generally thermo regulation is energetically expensive for many organisms. So, many smaller
animals are rarely found in extreme hot or cold climatic condition. Why? Write two specific reasons.
Ans. When it is cold out side, the animals tend to lose body heat quickly if they have large surface area
relative to their volume. They expend more energy to generate body heat by metabolism. Small animals
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have limited reserves of energy, so they cannot survive.
15. Rama and Shyama are very fond of enjoying fruit juices. Rama likes to drink fresh juice from a
local fruit juice shop while Shyama likes bottled juice. When compared, fresh juice appears to be
turbid while bottled juice does not. What is the reason for this observation?
Ans. (i) Fresh juice’s turbidity -cellular remnants
(ii) Bottled juice’s clarity – Pectinase and Proteases (of micro organismal origin) digest them, thus providing
clarity
16. Ecologists believe that communities with more species tend to be more stable than those with
less species. What attributes are taken into account while defining a stable community. Mention the
observation of David Tilman ecological experiments using outdoor plots.
Ans. Less variation in productivity from years to years, resilient to occasional disturbances, resistant to
invasions by alien species. Tilman found that plots with more species showed less year to year variations in
total biomass & increased diversity contributed to higher productivity.
17. What is disruptive selection?
Ans. Disruptive selection, like directional selection, favors the variants of opposite extremes
over intermediate individuals. Disruptive selection differs in that sudden changes in the environment creates
a sudden force favouring that In nature, sexual dimorphism is probably a common example.
18. Why it is essential that the chromosome number of an organism be the same from one
generation to the next generation?
Ans. Chromosomes contain the hereditary information of a cell. If daughter cell is produced with missing
chromosomes or additional chromosome, this error could result in the death of the cell in the absence of
inappropriate chromosome. For example, suppose the chromosome with the information needed to
produce digestive enzymes is missing; the cell would not have the enzymes needed to digest food.
19. SCP- One of the alternate source of protein for animal and human beings. Expand this term and
how it could ease the pressure on agriculture and dairy farming.
Ans. Single cell protein-Microbes like spirulina can be gown easily on materials like waste water from potato
processing plants, molasses, animal manure, even sewage in large quantities & serve as food as it is rich in
nutrients & specially proteins (microbial components).
SECTION-C
20. What is Double fertilization? Why it is called so? Elaborate the term Syngamy?
Ans. Fertilization: Pollen grains germinate on stigma & pollen tube grows through style. This pollen tube
reaches micropyle & releases two male gametes into embryo-sac. Fertilisation is the process of fusion of
male & female gametes (n+n) to form a diploid(2n) zygote.
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SYNGAMY: Fusion of one male gamete(n) with egg (n) so that Zygote(2n) is produced
First Fusion is of two Polar Nuclei(n+n=2n)
Second Fusion is of Male Gamete which Fuses with the fusion product of the two polar nuclei(3n)
Third Fusion fusion of male gamete with egg cell.
DOUBLE FERTILIZATION: In an embryo sac, two type of fusions are seen,i)Fusion of male gamete with
egg – First fertilisation, ii)Fusion of fusion product of polar nuclei with male gamete-Second Fertilisation.
Hence there are two Fertilizations occurring hence this phenomenon is known as double fertilization.
21. Differentiate b/w tubectomy and vasectomy.
Ans.
Tubectomy
Vasectomy
Method of sterilisaion in females
Method of sterilization in males
Fallopian tubes of both sides are cut and tied.
Vas deference is cut and tied.
It prevents ova to reach the place of fertilization. It prevents sperms to reach the place of fertilization.
22. With the help of a diagram show the double helix structure of DNA.
Ans.
23. What are restriction type-II enzymes?
Ans. Type II enzymes are those used in the vast majority of molecular biology techniques. Many are now
commercially available.
Many Type II restriction endonucleases recognise PALINDROMIC sequences (From Greek
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palindromos, running back again, recurring : palin, again)
A segment of double-stranded DNA in which the nucleotide sequence of one strand reads in reverse order
to that of the complementary strand. (always read from the same direction)
For example, EcoRI recognises the sequence
5''-G A A T T C-3''
3''-C T T A A G-5''
24. Give the difference b/w viral and cellular oncogenes.
Ans.
Viral Oncogenes
Cellular Oncogenes
These are the genes present in the oncogenic These are the genes present in normal cells
viruses, which effect oncogenic transformation and code for growth factors; when activated
of the cells they infect.
under certain conditions, can cause oncogenic
transformation of the cell.
25. Since the origin of life on earth and evolution there have been 5 episodes of mass extinction, but
the current rate of extinction is 100-1000 times. What are the main causes of high extinction rate and
how is it going to harm human beings?
Ans. Human activities are the basic cause for it.
Causes – 4 major causes (The evil Quartet along with suitable examples of each:(i) Habitat loss and fragmentation-decline in covered forest area from 14% to 6%.
(ii) Overexploitation- extinction of steller’s sea cow
(iii) Alien species invasion-Nile perch introduction into Lake Victoria resulted in extinction of 200 species
cichlid fish.
(iv) Co-extinction-coevolved plant pollinator mutualism.
Harms:
(a) Decline in plant production.
(b) Lowered resistance to Env. Perturbations like drought.
(c) Increased variability in certain ecosystem processes such as plant productivity, water use etc.
26. Explain in details the process of STP.
Ans. Treatment is done in two stages.
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Primary : Physical removal of particles large and small by filtration and sedimentation. Solids so left makes
primary sludge and the Supernatant becomes effluent.
Secondary: Primary effluent taken to large aeration tanks. Agitated mechanically and air pumped into it.
Aerobic microbes form masses with fungal filaments known as flocs.
Microbes consume organic matter in effluent for growth, thus BOD ( Biological oxygen demand) reduced.
Then it is passed into settling tank.
Bacterial flocs get sedimented , a small portion is kept to activate the sludge. Small part of activated
sludge used as inoculums in aeration tank and major part is pumped into large anaerobic sludge digesters
Anaerobic bacteria digest bacteria and fungi. Bacteria produce gases such as menthane, hydrogen
sulphide and CO2 – Biogas. And then secondary effluent is released into rivers and streams.
27. Most of the living organisms try to maintain the constancy of their internal environment in terms
of optimal temperature and osmotic concentration. What is the terminology used for this type of
constancy. How the following organisms do maintains it and also specifies the terms for that -:
a) Mammals
b) All plants
c) Birds in Siberia
d) Bacteria, Fungi & Lower Plants
Ans. Homeostasis.
a) Mammals regulate their body temperature by sweating profusely is summer and shivering in winterRegulators.
b) Conformers - Their body temperature and fluids changes with ambient temperature.
c) Migration -They move away temporarily from the stressful habitat to a more comfortable area and returns
when stressful period is over.
d) Bacteria fungi and lower plants produce various types of thick walled spores to survive unfavourable
condition. -Suspend.
SECTION-D
28. What are IUD’s?
Ans. Intra-Uterine Contraceptive Devices (IUCD):
IUCDs or IUDs are contraceptive devices which are placed inside the uterus. Small, flexible plastic frame.
Has copper wire or copper sleeves on it. Inserted into a woman‘s uterus through her vagina. Have two
strings, or threads, tied to them. Strings hang through the opening of the cervix into the vagina.
A provider can remove the IUD by pulling gently on the strings with forceps. Preventing sperm and egg
from meeting. Perhaps the IUD makes it hard for sperm to move through the woman‘s reproductive tract,
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and it reduces the ability of sperm to fertilize the egg. Prevent the egg from implanting itself in the wall of the
uterus. IUCDs prevent pregnancy by making the endometrium unreceptive to the fertilized ovum. It
stimulates the endometrium to release leukocytes (WBCs) and prostaglandins making it hostile to the sperm.
It also causes bizarre and irregular growth of the endometrium. This prevents implantation of 29 a fertilized
ovum. IUDs like Copper-Ts also come wrapped in copper. Copper is toxic to sperms and is a method of
enhancing the contraceptive effect of the IUDs.
The IUCDs can come in various shapes and sizes.
Lippes Loop: The Lippes loop consists of a thin plastic (or polyethylene)wire bent in a series of S-shapes
Copper T: T-shaped structure which stays inside the uterus with the long arm of the T along the uterine
cavity (endometrium) and the shorter arms transversely across the upper part of the endometrium.
Mirena: Releases a progesterone called levonorgestrel. It works by affecting ovulation, affecting the normal
growth of the endometrium and by affecting the cervical mucus so that the movement of sperm is obstructed.
In the United Kingdom, hormone based IUDs are known as Intra-uterine Systems (IUS).
29. Explain Hardy-Weinberg Principle.
Ans. Hardy-Weinberg principle: In population genetics, the idea that if a population experienced no
selection, no mutation, no migration, no genetic drift, and are random mating,then the frequency of each
allele and the frequencies of genotype in the population would remain the same (constant) from one
generation to the next generation.
p2 + 2pq + q2 = 1 or, (p + q)2 = 1
Calculation of allele frequencies Recessive traits:
If the frequency of a recessive trait such as cystic fibrosis or PKU is known, it is possible to calculate allele
frequencies and genotype frequencies using the Hardy Weinberg equation and its assumptions are as
follows:
i. Say 1 in 1, 2500 Indian newborns have cystic fibrosis which means that the frequency of homozygotes for
this recessive trait is q² = 1/2,500 = 0.0004
ii. The square root of the frequency of recessives is equal to the allele frequency of the cystic fibrosis allele q
= (0.0004)0.5 = 0.02
iii. The frequency of the normal allele is equal to 1 - the frequency of the cystic fibrosis allele p = 1- q = 1 0.02 = 0.98105
iv. The frequency of carriers (heterozygotes) for the cystic fibrosis allele is 2pq = 2 (0.98)(0.02) = 0.04 or
1/25
v. The frequency of homozygotes for the normal allele is p² = (0.98)² = 0.96
vi. Thus the population is composed of three genotypes at the calculated frequencies of homozygous normal
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= 0.96, heterozygous carriers = 0.04, homozygous affected = 0.0004.
30. What is family planning?And what are various methods involved to birth control?
Ans. Natural methods:

Behavioural methods: Behavioural methods depend on a good knowledge of the menstrual cycle
as well as adequate self control by the couple.

Coitus Interruptus: Coitus interruptus means ''interrupted sex". In this birth control method, the
penis is withdrawn from the vagina just before ejaculation.
The main advantage is that this method does not require the use of any drug, does not interfere with
normal body functions, and the couple can plan for pregnancy at any time they want. The main disadvantage
is that it is dependent almost wholly on the man''s self-control. The failure rate is high at 15 - 18%.

Rhythm method or Safe Period: This method requires a good knowledge of the female partner''s
menstrual cycle to identify the days on which sexual intercourse is possible without the risk of
pregnancy.

Avoiding vaginal Intercourse: Anal sex, oral sex or sex without penetrating the vagina
Artifical methods:

Barrier methods: In barrier methods of birth control, a barrier is placed between the penis and the
vagina during intercourse so that the sperm cannot meet the ovum for fertilization.

Male Condoms:, usually made of latex that covers the erect penis during penetration of the vagina.

Female Condoms: made of polyurethrane, loose sheath with two rings on either side. can be
inserted about 8 hours prior to sexual intercourse and can be kept in for about another 12 hours after
intercourse. Can be used more than once during this period.
o Condoms protect against pregnancy as well as sexually transmitted diseases (STDs), including
HIV/AIDS.
o Diaphragm: vaginal is a small saucer shaped rubber sheath with a metal coil in its rim which is fitted
across the mouth of the uterus (cervix). Cervical Cap: The cervical cap is a small dome-shaped rubber
device fitted on the cervix. It is uncomfortable to apply and is rarely used nowadays. Vaginal Sponge: The
sponge is a small polyurethrane round device which needs to be placed inside the vagina before sexual
intercourse. It releases spermicide which makes sperm inactive. It should be left in place for 8 hours after
use and can be used more than once during this time. The sponge also acts as a barrier contraceptive to
some extent since it swells up to fit across the cervix once it is inside the vagina.Hormonal Methods: Drugs
are used to either prevent ovulation or to prevent implantation of the embryo after fertilization.
Combined oral contraceptives contains two hormones similar to the natural hormones in a woman‘s body--an estrogen and a progestin
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SECTION-A
1. What are decomposers? Write their function.
Ans. a) Saprotrophs feed on dead bodies of organisms,
b) Decomposition and mineralization.
2. What is the difference between gaseous and sedimentary cycle?
Ans. a) Gaseous-Reservoir in atmosphere ,Nitrogen cycle
b) Sedimentary-Soil,e.g-phosphorus.
3. Why is the length of a food chain in an ecosystem generally limited to 3-4 trophic levels?
Ans. As 90% energy is lost in the form of heat from one trophic level to another, residual energy decreases
drastically within 2-3 trophic levels.
4. What are okazaki fragments?
Ans. Replication of the lagging strand takes place in small fragments called Okazaki fragments.
5. Give the name of enzymes used for DNA replication.
Ans. DNA ligases, DNA helicase, DNA polymerase
6. A flower is large in size, colorful and has notaries. Which pollination strategy it corresponds to?
Ans. Insect pollinated flowers.
7. What is pollen grain? Describe.
Ans. Pollen grains have two outer walls: i)Exine and ii) Intine
Exine is made up of sporopollenin (HARDEST NATURAL SUBSTANCE) . Mature pollen grains have two cells
– big vegetative cell & small generative cell. Generative cell forms two male gametes by mitotic division.
Pollen grains shed in 2-celled/3celled stage2
SECTION-B
8. Define commensalism and ammensalism.
Ans. Ammensalism One species hurts the other but the other is not affected.Penicillium secretes Penicillin
and kill Bacteria but by this Penicillium does not benefit. Algal bloom leads to death of fishes, but the death
of fishes is of no use to the algal bloom.
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Commensalism One species benefits and the other neither harmed nor benefited. The cattle egret catches
the insects disturbed by moving cattle, but the cattle neither harmed nor benefited.
9. A doctor was explaining to his students about a particular disease vector that booms particularly
during the rainy season (warm and humid). He also explained that one of the type of this disease can
show shivering effect and may be fatal. Name the type and its causative agent. Also explain the reason
for the other symptoms of the disease?
Ans. Malaria- C.O.(Pathogen).Plasomodium falciparum
Reasons for symptoms.- Parasite attack the RBCs and rupture then with the release of a toxin –haemozoin
which is responsible for chill and high fever .
10. Give the scientific term for the process of copying genetic message from one strand of DNA into
RNA. Only one strand of DNA is used during transcription. Why?
Ans. Transcription. If both are copied they would code for m-RNA molecules with different sequences hence
different proteins will be formed from same DNA sequence. If two strands of m-RNA are produced
simultaneously they would coil being complementary to each other.
11. Differentiate between true and false fruits.
Ans. True Fruit develops only from the ovary, e.g. mango, tomato False Fruitdevelops from other parts of
the flower as well as the ovary e.g. apple, peach etc. In case of apple thalamus is also involved for the
formation of the fruit.
12. What are the different types of gametes formed during sexual reproduction? Give examples.
Ans. Three types of gametes are formed in different organisms. These are
i. Isogametes or homogametes, e.g., an alga (Cladophora).
ii. Anisogametes,e.g., Spirogyra.
iii. Heterogametes, e.g., higher mammals including humans
13. Give the meaning of Green revolution, White revolution, Blue revolutio.
Ans. Green revolution - Crop production. White revolution - Milk production Bluerevolution - Fish production
14. What are the causes of biodiversity loss?
Ans. Major causes of biodiversity loss:
i) Habitat loss and fragmentation
ii) over exploitation
iii) Alien species invasions
iv) Co-extinctions and mass extinctions
v) overexploitation
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vi) urbanization
vii) pollution
viii) Global climate change
15. What does Oparin –Haldane hypothesis about the origin of life suggest. Who provided support to
their hypothesis?
Ans. They proposed that the life form could have come from the pre- existing non-living organic molecule(Like
RNA, proteins etc) .And formation of life was preceded by chemical evolution.Water vapour, CH4, CO2 and
NH3 were liberated from the molten mass.They formed earth’s atmosphere.These molecules would have
reacted to form organic molecules,(RNA, Proteins) due to UV rays, very high temperature. The theory was
supported by Harold Urey and Stanley Miller
16. What are the salient features of Genetic Code?
Ans. Nonambiguous—Particular codon will always code for same amino acid.
Degenerate—Number of codons can code for one amino acid.
Universal—Specific codon codes for same amino acid in all organisms.
17. What are special mechanism of reproduction?
Ans. Special mechanism of reproduction:
i) Apomixis- Production of seeds without fertilisation i.e. imitation of sexual reproduction process e.g. species
of Astereceae and grasses.
ii) Polyembryony- Occurrence of more than one embryo in a seed e.g.Orange.
SECTION-C
18. What do you understand by the term infertility?
Ans. Infertility‘ when a couple fails to conceive after one year of sexual life withoutcontraception. 80% of all
women desiring children, conceive within 1 year of marriage and another 10% within the second year.
According to the World Health Organisation, incidence of infertility is about 10 % worldwide. Another 1012% of all the other couples have only one child and wish to have more. The incidence of infertility is gradually
increasing all over the world.
19. Explain the process of tissue culture in details.
Ans. Tissue culture- cultured with any plant part called explant. Types –
1. Meristem Culture –When apical part is taken and cultured. Uses: a)Rapid clonal multiplication b)Production
of virus free plants c)Production of transgenic plants d)Germplasm collection
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2. Protoplast culture and somatic hybridization- The plant cell lacking cell wall is protoplast. Fusion of
protoplast is done by Polyethylene glycol. Pomato is somatic hybrid of potato and tomato.
3. Micropropagation-Tissue culture technique used for rapid vegetative propagation ofornamental plants and
fruit trees
4. Somaclone-Plants obtained from single plants by vegetative propagation.
20. What does Oparin –Haldane hypothesis about the origin of life suggest. Who provided support to
their hypothesis?
Ans. They proposed that the life form could have come from the pre- existing non-living organic molecule (Like
RNA, proteins etc) .And formation of life was preceded by chemical evolution.Water vapour, CH4, CO2 and
NH3 were liberated from the molten mass.They formed earth’s atmosphere.These molecules would have
reacted to form organic molecules,(RNA, Proteins) due to UV rays, very high temperature. The theory was
supported by Harold Urey and Stanley Miller
21. Define the following terms:
(a) IUI
(b) AIH
(c) AID
Ans. Intra-Uterine Insemination (IUI): This method is used in men with moderatelylow sperm count. the
semen is collected by masturbation, washed and centrifuged to increase the sperm density. This high density
sperm sample is now injected into the uterus, bypassing the vagina. The chances of hostile cervical mucus is
thus eliminated. Since the sperm is injected into the uterine cavity, chances of pregnancy is increased. The
procedure should be done within 2 hours of collecting the semen.
Insemination with Husband''s Semen (AIH) This is done in cases of impenetrable cervical mucous or when
disease or deformity of the cervix makes it impossible for the sperm to enter the uterus. It is also carried out in
cases of impotence or premature ejaculation.
Insemination with Donor Semen (AID) AID is usually carried out in couples where the husband suffers
from azoospermia
22. How replication of DNA takes place in eukaryotes?
Ans. Replication of DNA In Eukaryotes Definition: "Process by which DNA produces daughter DNA
molecules which are exact copies of the original DNA." In eukaryotes, DNA is double stranded. The two
strands are complementary to each other because of their base sequences.
Semi-conservative method of DNA replication
Important points:
(i) Most common method of DNA replication.
(ii) Takes place in the nucleus where the DNA is present in the chromosomes.
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(iii) Replication takes place in the S-phase (synthesis phase) of the interphase nucleus.
(iv) Deoxyribose nucleotides needed for formation of new DNA strands are present in nucleoplasm. At the time
of replication, the two strands of DNA first separate.
Each strand then acts as a template for the formation of a new strand. A new strand is constructed on each
old strand, and two exactly identical double stranded DNA molecules are formed. In each new DNA
molecule, one strand is old (original) while the other is newly formed. Hence, Watson and Crick described
this method as semi-conservative replication. (A) An overall process of DNA replication showing replication
fork and formation of new strands template and lagging template.
23. What is divergent evolution?
Ans. The evolutionary pattern in which two species gradually become increasingly different to each other. This
type of evolution often occurs when closely related species diversify to new habitats. On a large scale,
divergent evolution is responsible for the creation of the current diversity of life on earth from the first living
cells. On a smaller scale, it is responsible for the evolution of humans and apes from a common primate
ancestor.
24. What are the applications of HGP?
Ans. Application of Human genome project -: Identification of defective genes. -: Opportunity to offer early
treatment. -: Identification of genes that confer susceptibility to certain disease. -: Prediction of protein that the
genes produce. -: Drug designing to enhance or inhibit the activities of the proteins.
25. What are the different types of gametes formed during sexual reproduction? Give examples.
Ans. Three types of gametes are formed in different organisms. These are
i. Isogametes or homogametes, e.g., an alga (Cladophora).
ii. Anisogametes,e.g., Spirogyra.
iii. Heterogametes, e.g., higher mammals including humans
26. What is the difference between seasonal breeders and continuous breeders?
Ans.
Seasonal breeders.
Continuous breeders.
Mammals which exhibit oestrous
/menstrual cycle only during their
favorable seasons in their
reproductive phase.
Mammals which are reproductively
active throughout their reproductive
phase.
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27. A segment of DNA-3’—TTCACGGGGATG—5’ was translated into an oligopeptide lysine- serineproline- tyrosine in the respective sequence.
(i) Write the codons for these four amino acids.
(ii) If the first adenine in the DNA segment is substituted by Guanine, what will be the sequence of
amino acids in the new oligopeptide?
(iii) Write the anticodons for these amino acids.
Ans. 1-Lysine- AAG
Serine -UCC
Proline- CCC
Tyrosine- UAC
2- Lysine – Proline- Proline- Tyrosine
3-Anticodon for these amino Acid Lysine – UUC, Proline -GGG,
Tyrosine –AUG
SECTION-D
28. Biomass is a more meaningful measure of population size. Explain with an example.
Ans. (i) Population large Total number is not an easily adoptable measure. Counting takes long time or
practically impossible
(ii) There is no need to know the absolute population size for some investigations.
(iii) Number may sometimes be misleading e.g. In a given area there are 200Parthenium plants and a single
banyan tree. Here biomass size of the banyan tree is much more than those of 200 Parthenium plants.
29. Since the origin of life on earth and evolution there have been 5 episodes of mass extinction, but
the current rate of extinction is 100-1000 times. What are the main causes of high extinction rate and
how is it going to harm human beings?
Ans. Human activities are the basic cause for it.
Causes – 4 major causes (The evil Quartet along with suitable examples of each:(i) Habitat loss and fragmentation-decline in covered forest area from 14% to 6%.
(ii) Overexploitation- extinction of steller’s sea cow
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(iii) Alien species invasion-Nile perch introduction into Lake Victoria resulted in extinction of 200 species cichlid
fish.
(iv) Co-extinction-coevolved plant pollinator mutualism.
Harms:
(a) Decline in plant production.
(b) Lowered resistance to Env. Perturbations like drought.
(c) Increased variability in certain ecosystem processes such as plant productivity, water use etc.
30. What is artificial hybridisation?
Ans. ARTIFICIAL HYBRIDISATION: Types of cross-pollination performed by man for crop improvement. It is
achieved by
i) Emasculation i.e. removal of anthers from the flower bud of a bisexual flower before the anther dehisces
using a pair of forceps
ii) Bagging i.e. covering the emasculated flowers with a bag of suitable size to protect them from contamination
with unwanted pollen
If flower is unisexual, emasculation is not needed. Flower bud is bagged & once the stigma becomes receptive,
pollination is done using desired pollen & the flower is rebagged
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SECTION-A
1. Give the process of creation of r-DNA.
Ans. Isolation - Digestion - Fractionation - Purification of the TARGET fragment - Cloning into vectors Transformation of host cell and selection - Replication - Analysis - Expression of DNA.
2. Any DNA flanked at its two borders by T-DNA can be integrated into the plant genome. Name the
vector used for this plant gene transfer?
Ans. Tumor inducing plasmids (Ti Plasmids)
3. Who gave the theory of Natural Selection?
Ans. Charles Darwin
4. What is Evolution?
Ans. Evolution: The process that results in heritable changes in a population spread over many generations
(change in allele frequencies over time) leading to diversity of organisms on earth. It is the genetic change in a
population or species over generations ( Genes mutate, individuals are selected, and populations evolve).
5. What are the differences between detritus and grazing food chains?
Ans. a) Begins with Detritus-dead and decaying organic matter.
b) Grazing-Begins with Living green plants.
6. Give account of factors affecting the rate of decomposition.
Ans. a) Climatic factor – i) temp ii) soil
b) Chemical quality of detritus Higher temp and moist condition – high rate of decomposition Dry soil, High
temp – Low rate
7. What are the various factors of environment?
Ans. Abiotic factors Biotic factors Temperature, soil, Microorganisms, plants, water, light
Biotic factors Microorganisms, plants, water, light Animals
8. Many mammals from colder climates generally have shorter ear and limbs in comparison to the
mammals of other biome . Why? Which general principle is followed?
Ans. To minimize heat lose. This is called the Allen''s Rule.
SECTION-B
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9. What are the basis to decide on biodiversity conservation?
Ans. Biodiversity conservation: Reasons for conservation can be grouped into three categories:
(a) Narrow utilitarian-for deriving direct economic benefit from nature.
(b) Broad utilitarian-as biodiversity plays a major role in many ecosystem services.
(c) Ethical-we need to realise that every species has an intrinsic value and we need to pass on our biological
legacy to future generations.
10. Categorize the followings statement into narrowly utilitarian, broadly utilitarian and ethical reason:(i) Every species in biodiversity has an intrinsic value even if it not of value to us.
(ii) Human beings device a number of economic benefits like food, fiber etc from biodiversity.
(iii) Biodiversity provides ecosystem services which can not be given price tag.
Ans. (i) Ethical
(ii) Narrowly utilitarian
(iii) Broadly utilitarian
11. What are radio-active waves and what are their disadvantages?
Ans. Radioactive wastes
(a) Emit radiations and damage biological organisms.
(b) Nuclear wastes are called potent pollutants, as they are lethal even in lower doses.
Disadvantages of nuclear plants
(a) Accidental leakages may happen.
(b) Unsafe disposal of radioactive wastes.
(c) Radiation emitted cause mutations in organisms.
(d) Radiation causes genetic disorders.
12. What are the effects of deforestation?
Ans. Effects of deforestatio:
(a) Leads to global warming due to excess carbon-dioxide
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(b) Loss of biodiversity
(c) Damage to hydrological cycle
(d) Leads to soil erosion
(e) Desertification of land
13. What are benefits of transgenic animals?
Ans. 1. To know how genes contribute to development of disease.
2. To use proteins for treatment of disease.
3. To verify vaccine and chemical safety.
14. A method to present infestation of a nematode Meloidegyne incognitia on roots of tobacco is
silencing the specific mRNA. What is the scientific name of the technique? How is this performed by
ds-RNA?
Ans. RNA interference (RNAi):
This technique involves silencing of specific mRNA due to a Complementary ds RNA molecule that binds to
and prevents translation of m RNA i.e. RNA has been silenced.
15. What are special mechanism of reproduction?
Ans. Special mechanism of reproduction:
(i) Apomixis- Production of seeds without fertilisation i.e. imitation of sexual reproduction process e.g. species
of Astereceae and grasses.
(ii) Polyembryony- Occurrence of more than one embryo in a seed e.g.Orange.
16. Differentiate between true and false fruits.
Ans. True Fruit develops only from the ovary, e.g. mango, tomato False Fruitdevelops from other parts of the
flower as well as the ovary e.g. apple, peach etc. In case of apple thalamus is also involved for the formation
of the fruit.
17. What are the different types of gametes formed during sexual reproduction? Give examples.
Ans. Three types of gametes are formed in different organisms. These are
i. Isogametes or homogametes, e.g., an alga (Cladophora).
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ii. Anisogametes,e.g., Spirogyra.
iii. Heterogametes, e.g., higher mammals including humans.
18. Why it is essential that the chromosome number of an organism be the same from one generation
to the next generation?
Ans. Chromosomes contain the hereditary information of a cell. If daughter cell is produced with missing
chromosomes or additional chromosome, this error could result in the death of the cell in the absence of
inappropriate chromosome. For example, suppose the chromosome with the information needed to
produce digestive enzymes is missing; the cell would not have the enzymes needed to digest food.
SECTION-C
19. What do you understand by the term infertility?
Ans. Infertility‘ when a couple fails to conceive after one year of sexual life withoutcontraception. 80% of all
women desiring children, conceive within 1 year of marriage and another 10% within the second year.
According to the World Health Organisation, incidence of infertility is about 10 % worldwide. Another 1012% of all the other couples have only one child and wish to have more. The incidence of infertility is gradually
increasing all over the world.
20. What are the rules of segregation and independent assortment?
Ans. Rule of segregation (Separation): Gametes (sex cells) only receive one allele from the original gene.
Rule of Independent assortment: One trait will not determine the random selection of another. Incomplete
dominance: When one allele of a gene is not completely dominant over the other and the F1 hybrids are
intermediate between two parents. The phenotypic and genotypic ratio is same.1:2:1 in F2 generation. E.g.
Snapdragon or Antirrhinum majus
21. Due to which reasons Mendel’s work of inheritance though published went unrecognized?
Ans. 3 reasons were there:
(i) Lack of communication means at that time
(ii) His concept of gene as controlling unit was not accepted,as his contemporaries observed variation
continuously in nature
(iii) His approach of using mathematics and stataistics to biology wasn’t accepted
22. Explain the process of tissue culture in details.
Ans. Tissue culture- cultured with any plant part called explant.
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Types –
1.Meristem Culture –When apical part is taken and cultured. Uses: a)Rapid clonal multiplication b)Production
of virus free plants c)Production of transgenic plants d)Germplasm collection
2. Protoplast culture and somatic hybridization- The plant cell lacking cell wall is protoplast. Fusion of
protoplast is done by Polyethylene glycol. Pomato is somatic hybrid of potato and tomato.
3.Micropropagation-Tissue culture technique used for rapid vegetative propagation ofornamental plants and
fruit trees
4.Somaclone-Plants obtained from single plants by vegetative propagation.
23. SCP- One of the alternate source of protein for animal and human beings. Expand this term and
how it could ease the pressure on agriculture and dairy farming.
Ans. Single cell protein-Microbes like spirulina can be gown easily on materials like waste water from
potato processing plants, molasses, animal manure, even sewage in large quantities & serve as food as it is
rich in nutrients & specially proteins (microbial components).
24. Define commensalism and ammensalism.
Ans. Ammensalism One species hurts the other but the other is not affected. Penicillium secretes Penicillin
and kill Bacteria but by this Penicillium does not benefit. Algal bloom leads to death of fishes, but the death
of fishes is of no use to the algal bloom.
Commensalism One species benefits and the other neither harmed nor benefited. The cattle egret catches
the insects disturbed by moving cattle, but the cattle neither harmed nor benefited.
25. Write the scientific name of the organism that T.H.Morgan selected for his experiment . Why did he
choose this organism ?
Ans. Drosophila melanogastar
Reasons
(a) could be grown on simple synthetic medium in the laboratory
(b) Short life cycle.----two weeks
(c) single mating could produce a large number of progeny flies
(d) clear differentiation of sex .
(e) has many types of valuation
26. Stanley Miller & Urey experimentally proved the chemical evolution of life by creating condition
similar to the primitive atmosphere, in the laboratory. Name the gases filled by them in the flask .In
what form was the energy supplied for the chemical reaction to occur?
For how long the experiments run continuously?
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Ans. (i) CH4 , H2, NH3 & water vapours at 800’c.
(ii) Electric discharge in closed flask containing gases (i.e. CH4 , H2, NH3 & water vapours)
(iii) Seven days.
27. Give details of evolution.
Ans. Precambrian: Origin of life, Oxygen evolution through photosynthesis
Cambrian Flourishing of the invertebrates, increase in algal diversity, appearance of vertebrates.
Ordovician Plants begin to colonize land. Silurian Increase in diversity of fish.
Devonian Amphibians appear
Carboniferous Extensive forest,dominance of amphibians,increase in diversity of insects,first reptiles appear.
Permian Age of reptiles begin
Triassic Dinosaurs evolve and spread, first mammal appear
Jurassic First bird and first flowering plant appear.
Cretaceous Dominance of flowering plants.
Tertiary Age of mammals begin
Quarternary Evolution of human, Large mammals and birds become extinct.
SECTION-D
28. Define the following terms :
(a) Acrosome
(b) Amniotic sac
(c) Birth
(d) Parturition Blastocyst
(e) Cervix
(f) Clitoris
(g) Coitus
Ans. Acrosome- the part of a sperm cell that contains an enzyme – (This enables a sperm cell to penetrate an
egg.) Afterbirth-placenta and fetal membrane expelled from the uterus after the birth of a baby
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Amniotic sac-fluid-filled membrane or sac that surrounds the developing embryo while in the uterus.(protects
baby from hard shocks, keeps it at a constant temperature. )
Birth-the process of being born. process by which baby moves from the uterus into the outside world.
Parturition Blastocyst = blastula = early stage of an embryo; a liquid-filled sphere whose wall is composed of
a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus
occurs
Cervix- lower part, or neck, of uterus. (Opening to the uterus.)
Clitoris-small, sensitive organ in front of the vagina
Coitus-synonym for sexual intercourse
29. Give the process of DNA replication in details.
Ans. The various steps involved in this process are summarized as follows:
i. Mechanism of replication starts at a specific point of the DNA molecule, called origin.
ii. At origin, DNA strand breaks because of an incision (nick). This is made by an enzyme called incision
enzyme (endonuclease).
iii. The hydrogen bonds joining the two strands are broken by the enzyme.
iv. The two strands start unwinding.
This takes place with the help of a DNA unwinding enzyme Helicases.Two polynucleotide strands are thus
separated.
v. The point where the two strands separate appears like a fork or a Y-shape. This is described as
a replicating fork.
vi. A new strand is constructed on each old strand. This takes place with the help of a small RNA
primer molecule which is complimentary to the DNA at that point.
vii. Each old DNA strand acts as a template (site) for the construction of new strand. The RNA primer attaches
itself to the old strand and attracts the enzymes(DNA polymerase III) which add new nucleotides
through base complementation. The deoxyribose nucleotides are present in the surrounding nucleoplasm.
New DNA strand is thus constructed opposite to each old strand
viii. Formation of new complementary strand always begins at the 3'' end of the template strand (original
strand) and progresses towards the 5'' end (i.e in 3'' - 5'' direction). Since the new strand is antiparallel to the
template strand, it is obvious that the new strand itself is always developed in the, 5''-3'' direction. For this
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reason when the two original strands separate (then with respect to the origin of separation), one acts as 3''-5''
template while the other acts as 5''- 3'' template.
ix. Of the two, the replication of 3''-5'' template begins first. Hence the new strand formed on it is called
the leading strand. The other template (5''-3'') must begin replication at the fork and progress back toward the
previously transcribed fragment. The new strand formed on it is called the lagging strand.
x. Replication of the lagging strand takes place in small fragments calledOkazaki fragments. These are then
connected together by the enzymeligase.
xi. Replication may take place in only one direction on the DNA helix (unidirectional) or in two directions
(bidirectional).
xii. At the end of the process, two double stranded DNA molecules are formed from the original DNA molecule.
30. Describe the relationship between genes and chromosome of diploid organism and the terms used
to describe them,with the help of a well labelled diagram.
Ans.
Terms
Locus
Allele
Homozygous
Heterozygous
Homozygous Dominant
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Meaning
Example
Address/ location of a gene in a
chromosome
Allelomorphs= alternative form
of a gene
Both alleles of a gene at a locus
similar
Both alleles of a gene at a locus
dissimilar
Both alleles of a gene at a locus
similar & dominant
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T,A.b,d etc
T and t OR A and a etc
AA or aa
Aa or Tt etc
AA
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Homozygous recessive

Save your marriage

Infertility

Process

Processing
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Both alleles of a gene at a locus aa
similar & recessive
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SECTION-A
1. What is water pollution?
Ans. Water pollution :Biological Oxygen Demand (BOD) indicates the amount of dissolved oxygen utilised
by the microorganisms for oxidising the oxdisable organic matter present in the water body. Greater the
organics, greater would be the pollution and lesser the dissolved oxygen.
2. Define bio-magnification.
Ans. Bio magnification Increase in concentration of the toxicant at successive tropic levels Bio
magnification of DDTIN Aquatic food chain
Water- Zooplankton- Small Fish- Large Fish -Fish-eating Birds,
0.0003 ppm- 0.04- ppm- 0.5 -ppm -2 ppm- 5 ppm
3. What is ART?
Ans. ART is assisted reproductive technologies.
4. What is MTP?
Ans. Termination of pregnancy before full term is called is MTP.
5. Give salient features of the two strands of DNA?
Ans. Two chains are complementary to each other. Two chains are held together byhydrogen bond.
Adenine-Thymine pair has two hydrogen bonds. Guanine-Cytosine pair has three hydrogen bonds.
6. Two villagers were arguing for the nutritive value of milk and curd? Being a normal science
student and having studied the biochemistry of both the products, tell which one is
more nutritive and justify it.
Ans. Curd is more nutritious because it have vitamin B12, and is synthesized by LAB (absent in milk).
7. The name virus generally brings in our mind havoc that they are our enemies. There is a category
of virus which has species specific narrow spectrum, has insecticidal application, having no impact
on plants and other animals. Name the category and give one example.
Ans. Baculloviruses is the category. Eg :- Nucleopolyhedrovirus
8. Define semen and spermiation.
Ans. SEMEN:- The mixture of seminal plasma and spermatozoa is called semen.
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SPERMIATION:- It is the process of transformation of spermatids into spermatozoa is known as spermiation
SECTION-B
9. Why it is essential that the chromosome number of an organism be the same from one generation
to the next generation?
Ans. Chromosomes contain the hereditary information of a cell. If daughter cell is produced with missing
chromosomes or additional chromosome, this error could result in the death of the cell in the absence of
unappropriate chromosome. For example, suppose the chromosome with the information needed to produce
digestive enzymes is missing; the cell would not have the enzymes needed to digest food
10. What is central dogma of life and who proposed it?
Ans.It was Propose by F.Crick, it states that genetic information flows from DNA-RNA-Protein
11. Differentiate b/w GIFT and ICSI.
Ans.
GIFT
ICSI
1. called as gamete intra
1. intra cytoplasmic sperm
fallopian transfer(b).transfer of transfer this is a special
ovum from a donor female to technique to prepare embryo
provide suitable environment . in lab .
2. sperm is not directly
injected to ovum
2. The sperm is directly
injected to ovum .
3. no artificial insemination is 3. artificial insemination is
done
done for infertile coupl
12. (i) Explain metastasis. Why is it fatal?
(ii) The lymphocytes are of two types B and T-cells. Why are they called so?
(iii) A person was injured in a road accident and required an urgent immune response. What should
be done?
Ans. (i) Metastasis is the property of tumor cells, which get separated from a tumor, spread to different sites
in the body through body fluids and produce secondary tumors wherever they are lodged. Since secondary
tumors are formed at several parts of the body, it is difficult to be diagnosed and treated; hence it is fatal.
(ii) Those lymphocytes which undergo maturation in the bone marrow are called B-cells while those which
undergo maturation in the thymus are called T-cells.
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(iii) Vaccine against Tetanus.
13. Dicot plants do show tumorous growth (crown gall disease) on the stem.
a. Name the microorganism responsible for this growth?
b. What causes the production of tumors?
Ans. a. Agro bacterium termifaciens
b. The transfer of bacterial DNA to the plant which integrates into the plant genome and produces hormones
for the over growth.
14. If total number of base pair is multiplied with distance between two consecutive bases,length of
DNA comes out to be appropriate 2.2 m .How is the packaging of DNA helix done in a tiny nucleus of
dimensions of approximately 10-6 m?
Ans. Negatively charged DNA is wrapped around positively changed histone protein octamer to form
nucleosome each containing 200 bp. Nucleosomes are the reapting units of chromatin which are packed to
form chromatin fibers which are further coiled & condensed to form chromosome
15. What is transforming principle? Explain with Griffith’s experiment.
Ans. Transformation experiment or Griffith effect.
• Griffith performed his experiments on Mice using Diplococcus pneumoniae. • Two strains of bacteria are
S-type and R-type cells.
• Experiments : Living S-strain Injected into mice →Mice killed
Living R-strain Injected into mice → Mice lived
Heat Killed S-strain Injected into mice → Mice lived
Living R-strain + Heat Killed S-strain Injected into mice→ Mice killed
# Grffith concluded that R type bacteria is transformed into virulent form. #Transformation is the change in
the genetic constitution of an organism by picking up genes present in the remains of its relatives.
16. Selection of recombinants due to inactivation of antibiotics is a cumbersome procedure. Why?
Explain the alternative method to overcome this difficulty?
Ans. (i) It requires simultaneous planting on two plants having different antibiotics.
(ii) Development & use of selectable marker which differentiate recombinats from nonrecombinats on the
basis of there ability to produce colour in the process of a chromogenic substance.
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17. What are e-wastes?
Ans. E-wastes
Unused or damaged computers, calculators, mobile phones etc.
Developed countries have plants for recycling e-wastes for recycling of metals.
In developing countries e-wastes are buried in landfills or incinerated
18. Madame Curie discovered Radium for the treatment of cancer. But she herself died of cancer.
What can be the reasons? Can virus and genes also cause cancer? Give some examples.
Ans. Prolonged exposure to ionic radiation is carcinogenic. Oncogenic viruses, cellular oncogenes or
protooncogenes on transformation can cause cancer.
SECTION-C
19. Explain the term OUTBREEDING DEVICES?
Ans. Continuation of self-pollination results in breeding depression. Flowering plants have developed
many devices to discourage self-pollination & encourage cross-pollination these are:
i) Bearing unisexual flowers
ii) Anther & stigma mature at different times
iii) Anther & stigma placed at different positions
iv) Self-incompatibility where pollen grains of a flower do not germinate on the stigma of the same flower
20. What is artificial hybridisation?
Ans. ARTIFICIAL HYBRIDISATION: Types of cross-pollination performed by man for crop improvement. It
is achieved by
i) Emasculation i.e. removal of anthers from the flower bud of a bisexual flower before the anther dehisces
using a pair of forceps
ii) Bagging i.e. covering the emasculated flowers with a bag of suitable size to protect them from
contamination with unwanted pollen
If flower is unisexual, emasculation is not needed. Flower bud is bagged & once the stigma becomes
receptive, pollination is done using desired pollen & the flower is rebagged.
21. State the qualities of a genetic material? Out of DNA & RNA, which one fulfills all the prerequisites of being a genetic material and why?
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Ans. Able to replicate, chemically & structurally stable, scope for mutation, able to express itself in the form
of Mendelian characters. DNA the genetic material.
As –OH functional group at 2` position of deoxy-ribose in RNA is a reactive group making RNA labile &
easily degradable, presence of Uralic instead of thiamine in RNA have more ability of RNA to mutation.
22. How to conserve biodiversity?
Ans. In-situConservation– Threatened /endangered plants and animals are provided with urgent measures
to save from extinction within their natural habitat( in wildlife sanctuaries, national parks & biosphere
reserves, sacred groves /lakes-i.e. inprotected areas) Biodiversity hotspots – regions with very high
levels of species richness and endemism. Norman Myers developed the concept of hotspots in 1998 to
designate priority areas for insitu conservation. They are the most threatened reservoir of biodiversity on
earth. In India 2 hotspots are there,e.g.Western ghats, and the Eastern Himalayas. Ex-situ Conservation –
Threatened animals & plants are taken out from their natural habitat & placed in a setting where they can
be protected and given care as in botanical gardens, zoological gardens, seed/pollen/gene banks.
23. Define the following: L-H SURGE, MENARCHE, OOGENESIS, PRIMARY SEX
ORGANS, SECONDARY Sex Organs
Ans. L-H SURGE:- it refers to maximum level of L-H during middle of menstrual cycle.
MENARCHE:- The beginning of menstruation at puberty in primate females is called as menarche.
OOGENESIS:- it is the formation of ova in the ovary by meiosis is known as oogenesis.
PRIMARY SEX ORGANS:- The organs producing male and female gametes are known as primary sex
organs.
SECONDARY Sex Organs:- The sex organs which perform important functions in the reproduction but do
not form gametes are called secondary sex organs.
24. What is Evolution?
Ans. Evolution: The process that results in heritable changes in a population spread over many generations
(change in allele frequencies over time) leading to diversity of organisms on earth. It is the genetic change in
a population or species over generations ( Genes mutate, individuals are selected, and populations evolve).
25. What do you understand by AI?
Ans. ARTIFICIAL INSEMINATION: Medical technological devices by which semen collected from a healthy
donor is artificially introduced into the vagina or uterus of female.
26. Mutualism often involves co-evolution of the mutualist . Explain this statement taking example of
plant animal relationship?
Ans. Evolution of the flowers & its pollinator species.
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Ex. Fig species can be pollinated only by its partner wasp species and no other species. In turn female fly
uses the fruit for laying its egg as well as nourishment of its larvae from the developing speed.
27. Gobar gas can be abundantly produced in rural areas from gobar with the help of gobar gas
plants. Slury acts as an exellent increase of soil fertility. Ecofriendly i.e. it does not cause pollution
when burnt, Assuming you as a chairman of KVIC, suggest the points of maximum utilization of
Gobar Gas, the mechanism of its production & ecofriendly aspects of Gobar gas to the villages.
Ans. Gobar gas can be abundantly produced in rural areas from gobar with the help of gobar gas plants.
Slury acts as an exellent increase of soil fertility. Ecofriendly i.e. it does not cause pollution when burnt
SECTION-D
28. What are the various methods of IVF?
Ans. Zygote intrafallopian transfer (ZIFT) infertility treatment where blockage in the fallopian tubes
prevents the normal binding of sperm to the egg. Egg cells removed from woman's ovaries, and in vitro
fertilised. Resulting zygote placed into the fallopian tube by laparoscopy. The procedure spin-off of the
gamete intrafallopian transfer (GIFT) procedure. ZIFT has a success rate of 64.8% in all cases.
Takes an average five weeks to complete a cycle of ZIFT. First, the woman must take a fertility medication
to stimulate egg production in the ovaries. The doctor will monitor growth of ovarian follicles, once they are
mature, woman will be injected with human chorionic gonadotropins (hCG). Eggs will be harvested
approximately 36 hours later, usually by transvaginal ovum retrieval. After fertilization in laboratory resulting
early embryos or zygotes are placed into the woman's fallopian tubes using laparoscope.
Gamete intrafallopian transfer (GIFT) assisted reproductive technology against infertility. Eggs removed
from a woman's ovaries, placed in one of the Fallopian tubes, along with the man's sperm. The technique,
which was pioneered by endocrinologist Ricardo Asch, allows fertilization to take place inside the woman's
body.
Takes, an average of four to six weeks to complete a cycle of GIFT. First, the woman must take a fertility
drug to stimulate egg production in the ovaries. The doctor will monitor growth of ovarian follicles, once they
mature, woman will be injected with Human chorionic gonadotropin (hCG). The eggs will be harvested
approximately 36 hours later, mixed with the man's sperm, and placed back into the woman's Fallopian
tubes using laparoscope.
Intracytoplasmic Sperm Injection (ICSI): technique in which a single sperm injected into the centre of the
egg, in order to achieve fertilization. Sperm is collected from the male partner by masturbation. Single
healthy sperm then injected into the prepared ovum. The advantage of this method is that only a single
sperm is needed - even men with a very low sperm count can become fathers with this treatment. Men found
to be azoospermic, that is with no sperm at all in the semen, sperm can be suctioned out of the vas deferens
( male tubes). Sperm can also be liberated from the testes itself by careful testicular biopsy and culture by a
method called MESA - Microepididymal sperm aspiration.
29. How replication of DNA takes place in eukaryotes?
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Ans. Replication of DNA In Eukaryotes Definition: "Process by which DNA produces daughter DNA
molecules which are exact copies of the original DNA." In eukaryotes, DNA is double stranded. The two
strands are complementary to each other because of their base sequences. Semi-conservative method of
DNA replication
Important points: (i) Most common method of DNA replication.
(ii) Takes place in the nucleus where the DNA is present in the chromosomes.
(iii) Replication takes place in the S-phase (synthesis phase) of the interphase nucleus.
(iv) Deoxyribose nucleotides needed for formation of new DNA strands are present in nucleoplasm. At the
time of replication, the two strands of DNA first separate.
Each strand then acts as a template for the formation of a new strand. A new strand is constructed on
each old strand, and two exactly identical double stranded DNA molecules are formed. In each new DNA
molecule, one strand is old (original) while the other is newly formed. Hence, Watson and Crick described
this method assemi-conservative replication. (A) An overall process of DNA replication showing replication
fork and formation of new strands template and lagging template.
30.How r-DNA is used in Diagnosis of diseases?
Ans. Genetic diagnosis
a. Diagnosing inherited disorders * Cystic fibrosis * Muscular dystrophy * Haemophilia A and B * Sickle cell
anaemia
b. Diagnosing cancer - certain cancers are caused by specific and reproducible mutations: e,g.
Retinoblastoma - childhood cancer of the eye. The heritable form (germ line mutation of one of the two
retinoblastoma allelles): mutation is detected in all cells. Spontaneous form: only detected in tumour tissue.
c. Blood group typing d. Prenatal diagnosis – eg determining the sex of foetus for those at risk of X-linked
disorders PCR is one of the most versatile techniques invented
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SECTION-A
1. What name is given to the individuals that are produced from one individual and are genetically
identical?
Ans. Clone
2. What is the special asexual reproductive structure in Chlamydomonas?
Ans. Zoospores
3. How does Penicillium (a fungus) reproduce asexually?
Ans. Penicillum reproduces asexually by means of conidia.
4. Define pollution.
Ans. Pollution: Any undesirable change in physical, chemical or biological characteristics of air, land, water or
soil which harms the human beings.
5. What is DNA?
Ans. DNA largest macromolecule made of helically twisted, two, antiparallel polydeoxyribonucleotide chains
held together by hydrogen bonds. X-ray diffraction pattern of DNA by Rosalind Franklin showed DNA a helix.
6. What are the different types of microbes present?
Ans. Protozoa, Bacteria, Fungi, Virus, Viroids, Prions (Proteinaceous infectious agents)
7. What benefits do microbes provide in kitchen?
Ans. Lactobacillus (LAB) Lactic acid Bacteria – form curd from milk,Fermentation of dough for dosa, idli (CO2
produced) Making bread –Baker‘s yeast. Saccharomyces cerevisiae. Cheese making
8. A person is physical fit, exercises, eats balanced diet but his neighborhood was always noisy which
disturbed his sleep. How can this situation affect the health of the person? Does this situation fit into
the definition of health?
Ans. No, he is not mentally fit. According to WHO- “health is the state of physical, mental and social wellbeing”.
SECTION-B
9. Why vegetative propagation is proved to be a boon to the agriculturists?
Ans. Vegetative propagation is especially beneficial to the agriculturists and horticulturists. The plants in which
viable seeds are not produced can be raised easily through vegetative propagation e.g. crops like bananas,
sugarcane, potato, etc. The seedless varieties of fruits are also grown by vegetative propagation.
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10. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves. What is the
reason behind it?
Ans. Cry protein of bt toxin in Bacillus thuringiensis is produced in an inactive state (pro-toxin). It remains
inactive until subjected to alkaline pH.
11. What are the various applications of biotechnology in medicine?
Ans. In medicine-genetically engineered insulin— Human insulin consists of Polypeptide chains A & B.
Insulin secreted as Prohormone, which contains C peptides, removed during maturation. In 1983, Eli Lilly, an
American company prepared 2 DNA sequences coding for chains A & B.
– Genes inserted into the cells and tissues to correct certain hereditary diseases.
Gene therapy Gene therapy corrects the gene defects in child or embryo. Deficiency of ADA causes SCID due
to the disorder of a gene. It can be cured by bone marrow transplantation. Functional ADA-cDNA is introduced
in lymphocyte and returned to the patient.
Molecular diagnosis -- PCR (Polymesase chain reaction) used for early diagnosis of
disorder. ELISA (Enzyme Linked Immunosorbent Assay) used to detect AIDS.
12. What is emergency oral contraceptive?
Ans. Emergency Oral Contraception After unprotected sex, emergency oralcontraception can prevent
pregnancy. Sometimes called postcoital or morning after ‘contraception. Mainly stops ovulation. Regular use
of emergency contraceptives has serious health hazards. Eg is i-pill.
13. What are the surgical methods towards birth control?
Ans. Surgical Methods: These are more or less permanent methods of contraception.
o Tubal Ligation: Both the female tubes are tied off and usually cut during tubal
ligation to prevent the sperm from reaching the
ovum during intercourse.
o Vasectomy: The two tubes which carry sperm from the testes to the penis are the
vas deferens. Tying them off and cut.
o Essure: Essure is a method in which small micro-inserts are placed at the mouth of the fallopian tubes to
cause scarring and block them. This prevents sperm from reaching the ovum for fertilization.
14. What are age pyramids?
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Ans. Age pyramids : Three ecological ages are: # Pre-reproductive, Reproductive and Post-Reproductive #
High proportion pre-reproductive individuals occur in expanding population # Pre-reproductive individuals are
uniform in stable population. # Pre-reproductive individuals are less in Declining population.
15. What is interference competition? Define competitive exclusion principles.
Ans. (i) Feeding efficiency may be reduced due to interference of another species. E.g. –Tiger and deer.
(ii)Two closely related species need same resource can not co-exist indefinitely.
16. Give the process of creation of r-DNA?
Ans. Isolation - Digestion - Fractionation - Purification of the TARGET fragment - Cloning into vectors Transformation of host cell and selection - Replication - Analysis - Expression of DNA
17. What measures should be taken to reduce global warming?
Ans. Reduce use of fossil fuel Efficient use of energy. Avoid deforestation Reduce human population Control
greenhouse gases.
18. What is the difference between the type of gametes and their transfer from male to female
organisms of higher animals and higher plants?
Ans. In higher animals, male gametes are motile and transferred to the female genital tract by insemination but
in higher plants male gametes are non-motile and they are carried to the embryo sac for fertilisation through
pollen tube.
SECTION-C
19. Why it is essential that the chromosome number of an organism be the same from one generation
to the next generation?
Ans. Chromosomes contain the hereditary information of a cell. If daughter cell is produced with missing
chromosomes or additional chromosome, this error could result in the death of the cell in the absence of
unappropriate chromosome. For example, suppose the chromosome with the information needed to
produce digestive enzymes is missing; the cell would not have the enzymes needed to digest food
20. Give details of DNA packaging.
Ans. DNA of eukaryotes is wrapped around positively charged histone proteins to form nucleosome.
Nucleosome contains 200 base pairs of DNA helix.
Histone octamer =2(H2a+H2b+H3+H4) Linker DNA bears H1 protein # Chromatin fibres formed by repeated
units of nucleosomes.
Non histone proteins required for packaging. Regions of chromatin, loosely packed and stains lightly is called
euchromatin. Regions of chromatin, densely packed and stains darkly is called heterochromatin.
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21. Rahul was suffering from the malfunctions of kidneys and need a replacement. His friend comes
forward to donate him a kidney but after through examination the doctors refused to accept the kidney.
Why he was refused to donate and what is it that the doctors check?
Ans. He underwent blood group and tissue typing / matching because the body is able to differentiate between
self non self .Defense systems may generate cell mediated immune response.
22. What is artificial hybridisation?
Ans. ARTIFICIAL HYBRIDISATION: Types of cross-pollination performed by man for crop improvement. It is
achieved by
i) Emasculation i.e. removal of anthers from the flower bud of a bisexual flower before the anther dehisces
using a pair of forceps
ii) Bagging i.e. covering the emasculated flowers with a bag of suitable size to protect them from contamination
with unwanted pollen
If flower is unisexual, emasculation is not needed. Flower bud is bagged & once the stigma becomes receptive,
pollination is done using desired pollen & the flower is rebagged
23. What are the common symptoms of STD’s in men and women?
Ans. Men






Swelling or tenderness in genital area.
Blisters ,sores or bumps around the mouth or genitals.
Fever,chills and aches.
Unusual itching.
Burning sensation when you pass urine or move your bowels.
White,watery or yellow disharge from the penis.
Women






Have fewer symptoms than men, often none at all. STDs can lead to cancer. Women should watch forBleeding that is not part of their period.
Pelvic or vaginal pain.
Discharge from the vagina.
Painful urination.
Unusual rash, sore or growth in the genital area.
24. What are special mechanism of reproduction?
Ans. Special mechanism of reproduction:
i) Apomixis- Production of seeds without fertilisation i.e. imitation of sexual reproduction process e.g. species
of Astereceae and grasses.
ii) Polyembryony- Occurrence of more than one embryo in a seed e.g.Orange.
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25. What are Restriction Enzymes?
Ans. Restriction enzymes are endonucleases
These are Bacterial enzymes
Different bacterial strains express different restriction enzymes
The names of restriction enzymes are derived from the name of the bacterial strain they are isolated from .
They cut (hydrolyse) DNA into defined and REPRODUCIBLE fragments
They are basic tools of gene cloning
26. What do you understand by the term infertility?
Ans. Infertility‘ when a couple fails to conceive after one year of sexual life without contraception. 80% of all
women desiring children, conceive within 1 year of marriage and another 10% within the second year.
According to the World Health Organisation, incidence of infertility is about 10 % worldwide. Another 10-12%
of all the other couples have only one child and wish to have more. The incidence of infertility is gradually
increasing all over the world.
27. What are cloning vectors?
Ans. Cloning vectors are extra-chromosomal 'replicons' of DNA which can be isolated and can replicate
independently of the chromosome. Vectors usually contain aselectable marker - a gene that allows selection
of cells carrying the vector e.g. by conferring resistance to a toxin. DNA of interest can be cloned into the
vector and replicated in host cells, usually one which has been well characterised.
SECTION-D
28. Give the details of Pest resistant plants
Ans. PEST RESISTANT PLANTS
Bt- cotton -- BT stands for Bacillus thuringiensis (Soil Bacteria). Bacterium produces proteins (Crystal Proteincry I AC, cry II AB). A crystalliane insecticidal protein that kills the insects. Hence cry-Genes have been
introduced in plants to produce crystal proteins as Protoxin (inactive toxin), which is converted to toxins in
alkaline medium (i.e. in the gut of insects) and cause death of the insect larva.
Protection of plants against nematodes – Nematode, Meloidogyne incognita infects tobacco plants &
reduces yield. Specific genes (DNA) from nematodes introduced into the plants using Agrobacterium
tumifecians (soil bacteria). Genes produce sense and antisense complementary RNA. Act as dsRNA and
initiates RNAi ( RNA interference) and silences the specific mRNA. Complementary RNA neutralizes the
specific RNA of nematodes by a process called RNA Interference and parasite cannot live in transgenic host.
29. What are the various methods of IVF?
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Ans. Zygote intrafallopian transfer (ZIFT) infertility treatment where blockage in the fallopian tubes prevents
the normal binding of sperm to the egg. Egg cells removed from woman's ovaries, and in vitro fertilised.
Resulting zygote placed into the fallopian tube by laparoscopy. The procedure spin-off of the gamete
intrafallopian transfer (GIFT) procedure. ZIFT has a success rate of 64.8% in all cases.
Takes an average five weeks to complete a cycle of ZIFT. First, the woman must take a fertility medication
to stimulate egg production in the ovaries. The doctor will monitor growth of ovarian follicles, once they are
mature, woman will be injected with human chorionic gonadotropins (hCG). Eggs will be harvested
approximately 36 hours later, usually by transvaginal ovum retrieval. After fertilization in laboratory resulting
early embryos or zygotes are placed into the woman's fallopian tubes using laparoscope.
30. Write a detail account of female reproductive system with its various parts and their functions.
Ans. Ovary: i) Each ovary contains immature ova (eggs) in follicles. ii) Females born with lifetime supply of
eggs(250,000-400,000 in each ovary) iii) Ovaries release ovum -. Almost all ova degenerate between birth and
puberty. iv) Approx. 400 eggs will be ovulated over woman's life. v) Egg is the largest human cell. vi) Ovaries
are located lower abdomen. 1 left and 1 on the right.
Fallopian tubes i) Two thin tubes attached to the upper sides of uterus ii) Tubes terminate near the ovaries
but are not attached iii) "Fimbriae" are finger-like structures on the end of each tube iv) Tubes conduct egg to
uterus by use of small hairs called "cilia" v) Fertilization of ovum takes place in the ampullary-isthmic
junction of the fallopian tubes. Egg viable for only 24-48 hours after ovulation.
Uterus: i) Pear-shaped organ located in lower abdomen ii) Muscles (myometrium) stretch to allow baby to
develop. Oxytocin starts labor contractions. iii) Lining of uterus (endometrium) thickens with blood-rich tissue
due to progesterone iv)Endometrium supports embryo/fetus during growth v) Placenta It is the interface
between baby and mother. If not pregnant, lining breaks down and is discharged frombody through vagina.
This is menstruation (period) vi)Cervix connects uterus to vagina. Like a door that opens during ovulation.
Cervical mucous closes the door at all other times.
Vagina: Birth canal: i)Menstrual blood leaves the body ii) Organ of intercourse
iii) Muscular stretches to allow a baby to grow 15
iv)Vaginal opening partly remains closed by thin membrane of tissue called hymen.May be stretched or torn
during any physical activity
Cervix: i)Located at inner end of vagina ii)Opening of uterus into vagina iii) Mucous prevents bacteria and
viruses from entering uterus iv)Lets sperm into uterus after ovulation v) Where baby also passes through
during vaginal birth
Gamete intrafallopian transfer (GIFT) assisted reproductive technology against infertility. Eggs removed from
a woman's ovaries, placed in one of the Fallopian tubes, along with the man's sperm. The technique, which
was pioneered by endocrinologist Ricardo Asch, allows fertilization to take place inside the woman's body.
Takes, an average of four to six weeks to complete a cycle of GIFT. First, the woman must take a fertility drug
to stimulate egg production in the ovaries. The doctor will monitor growth of ovarian follicles, once they mature,
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woman will be injected with Human chorionic gonadotropin (hCG). The eggs will be harvested approximately
36 hours later, mixed with the man's sperm, and placed back into the woman's Fallopian tubes using
laparoscope.
Intracytoplasmic Sperm Injection (ICSI): technique in which a single sperm injected into the centre of the
egg, in order to achieve fertilization. Sperm is collected from the male partner by masturbation. Single healthy
sperm then injected into the prepared ovum. The advantage of this method is that only a single sperm is
needed - even men with a very low sperm count can become fathers with this treatment. Men found to be
azoospermic, that is with no sperm at all in the semen, sperm can be suctioned out of the vas deferens ( male
tubes). Sperm can also be liberated from the testes itself by careful testicular biopsy and culture by a method
called MESA - Microepididymal sperm aspiration.
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SECTION-A
1. Two villagers were arguing for the nutritive value of milk and curd? Being a normal science student
and having studied the biochemistry of both the products, tell which one is more nutritive and justify it
?
Ans. Curd is more nutritious because it have vitamin B12, and is synthesized by LAB (absent in milk).
2. What is ART?
Ans. ART is Assisted Reproductive Technologies.
3. RNA was the first genetic material. Justify the statement.
Ans. Codes for protein synthesis, DNA is dependent on RNA for its synthesis.
4. It was diagnosed by a specialist that the immune system of a patient has been suppressed. A special
test was done for confirmation. Name the test as well as the disease the patient was suffering? Also
give its causative agent?
Ans. ELISA, AIDS, HIV (Human immuno deficiency virus )
5. Raju was curious to experiment a new brand of cigarette. Later on he found that he was unable to
quit smoking. Can this lead to addiction and what other problems can crop up?
Ans. Yes, increased incidence of lung cancer, coronary heart diseases, emphysema etc.
6. A white coloured, dry powdered substances is sprayed on the vulnerable plants to control butterfly
caterpillars. Guess what thing of biological origin may be there in. What is the source /micro-organism
of it?
Ans. (i) White powder is “Dry spores”
(ii) Source – Bacillus thuringiensis bacteria.
7. What is the main advantage of producing genetically engineered insulin?
Ans. Produces only A&B peptides. No C-Peptides produced . No need to remove C-Peptides during
maturation.
8. What are the different types of population growth pattern? Mention their differences.
Ans. a. Logistic and Exponential growth
b. S Shaped curve, J shaped curve. Limiting Factors, No-limiting Factors
SECTION-B
9. What are special mechanism of reproduction?
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Ans. Special mechanism of reproduction:
(i) Apomixis- Production of seeds without fertilisation i.e. imitation of sexual reproduction process e.g. species
of Astereceae and grasses.
(ii) Polyembryony- Occurrence of more than one embryo in a seed e.g.Orange.
10. The transfer of pollen grains in bisexual flowers is easier than in unisexual flowers? Explain this
statement.
Ans. Both male and female reproductive organs i.e., stamens and pistils respectively are located in the in the
same flower and are close to each other in bisexual flower but in unisexual flower they are present in
two different flowers.
11. What is the difference b/w menarche and menopause?
Ans.
Menarche
Menopause
It refers to beginning of
menstruation at puberty in
primates/ human females.
It refers to stoppage of menstruation
at the age of 45-50 in primates/
human females.
It marks the beginning of
reproductive phase.
It marks the end of reproductive
phase.
12. The genes for haemophilia are located on chromosome of humans. It is normally impossible for a
haemophilic father to pass the gene to his son. Why?
Ans. It is ‘X’ linked disorder and the father passes his only ‘X’ chromosomes carrying haemophilic gene to his
daughter and not to the son (who receives ‘Y’ chromosome).
13. What are the different types of gametes formed during sexual reproduction? Give examples.
Ans. Three types of gametes are formed in different organisms. These are
i. Isogametes or homogametes, e.g., an alga (Cladophora).
ii. Anisogametes,e.g., Spirogyra.
iii. Heterogametes, e.g., higher mammals including humans.
14. What is the advantage of presence of sickle allele in the heterozygous condition?
Ans. Sickle allele in heterozygous condition protects the person against malaria (RBC having sickle shaped
hemoglobin were readily infected with malarial parasite and with the bursting of such an RBC, parasites
present in the sickled cells also die.
15. Why are grains and vegetables produced in organic farms supposed to be better for human
consumption than those produced in farms where chemical fertilizers, pesticides etc. has been used?
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Ans. Chemical fertilizers / pesticides --non -biodegradable , enter into food chain through vegetables / grains ,
causes biomagnification in humans . In organic farms manure is used, whose produce causes no harm to
human health.
16. Only 1% energy of sun is trapped by green plants and only 10% energy is transferred from one
trophic level to another. Based on this data how will you justify the first law of thermodynamics?
Ans. Rest of the energy is liberated in the form of heat. 90% of the energy is used for growth and maintenance
and rest 10% remains that is passed on.
17. Why placenta is called Functional Unit?
Ans. It is called so as it helps in the transfer of oxygen and nutrients to the embryo from mother and removal of
carbon di-oxide and excretory waste from the embryo.
18. How do normal cells get transformed into cancerous neoplastic cells? Mention the differences
between viral oncogenes and cellular oncogenes.
Ans. The transformation of normal cells into cancerous neoplastic cells is induced by physical, chemical and
biological agents collectively called carcinogens; they lose the property of contact inhibition.
SECTION-C
19. What is artificial hybridisation?
Ans. ARTIFICIAL HYBRIDISATION: Types of cross-pollination performed by man for crop improvement. It is
achieved by
(i) Emasculation i.e. removal of anthers from the flower bud of a bisexual flower before the anther dehisces
using a pair of forceps
(ii) Bagging i.e. covering the emasculated flowers with a bag of suitable size to protect them from
contamination with unwanted pollen
If flower is unisexual, emasculation is not needed. Flower bud is bagged & once the stigma becomes receptive,
pollination is done using desired pollen & the flower is rebagged.
20. What do you understand by STD?
Ans. Sexually transmitted diseases (also called STDs, or STIs for sexually transmitted infections): Infections
transferred from one person to another through sexual contact. According to the Centers for Disease Control
and Prevention, there are over 15 million STD cases reported annually in the United StatesMore than 25
diseases that are transmitted through sexual activity. Other than HIV, the most common STDs in the United
States are chlamydia, gonorrhea, syphilis, genital herpes, human papillomavirus, hepatitis B, trichomoniasis,
and bacterial vaginosis. Adolescents and young adults are the age groups at greatest risk for acquiring an
STD. Approximately 19 million new infections occur each year, almost half of them among people ages 15 to
24.
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Some STDs can have severe consequences, especially in women, if not treated, which is why it is so
important to go for STD testing. Some STDs can lead to pelvic inflammatory disease, which can
cause infertility, while others may even be fatal. STDs can be prevented by refraining from sexual activity, and
to a certain extent, some contraceptive devices, such as condoms.
21. What is Saltation?
Ans. Saltation (from Latin, saltus, "leap") is a sudden change from one generation to the next, that is large, or
very large, in comparison with the usual variation of an organism. The term is used for occasionally
hypothesized, nongradual changes (especially single-step speciation) that are atypical of, or violate, standard
concepts involved in neo-Darwinian evolution.
22. What are the various stages of PCR?
Ans. PCR is a cycle of three steps:
1. DENATURATION - the strands of the DNA are melted apart by heating to 95°C
2. ANNEALING - the temperature is reduced to ~ 55°C to allow the primers to annealto the target DNA
3. POLYMERISATION/EXTENSION - the temperature is changed to the optimum temperature in order for the
DNA polymerase to catalyse extension of the primers, i.e.to copy the DNA between the primers.
23. SCP- One of the alternate source of protein for animal and human beings. Expand this term and
how it could ease the pressure on agriculture and dairy farming.
Ans. Single cell protein-Microbes like spirulina can be gown easily on materials like waste water from potato
processing plants, molasses, animal manure, even sewage in large quantities & serve as food as it is rich in
nutrients & specially proteins (microbial components).
24. How to conserve biodiversity?
Ans. In-situ Conservation– Threatened /endangered plants and animals are provided with urgent measures
to save from extinction within their natural habitat( in wildlife sanctuaries, national parks & biosphere
reserves, sacred groves /lakes-i.e. inprotected areas).
Biodiversity hotspots – regions with very high levels of species richness and endemism. Norman Myers
developed the concept of hotspots in 1998 to designate priority areas for insitu conservation. They are the
most threatened reservoir of biodiversity on earth. In India 2 hotspots are there,e.g.Western ghats, and the
Eastern Himalayas.
Ex-situ Conservation –Threatened animals & plants are taken out from their natural habitat & placed in a
setting where they can be protected and given care as in botanical gardens, zoological gardens,
seed/pollen/gene banks.
25. What are radio-active waves and what are their disadvantages?
Ans. Radioactive wastes
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(a) Emit radiations and damage biological organisms.
(b) Nuclear wastes are called potent pollutants, as they are lethal even in lower doses.
Disadvantages of nuclear plants
(a) Accidental leakages may happen.
(b) Unsafe disposal of radioactive wastes.
(c) Radiation emitted cause mutations in organisms.
(d) Radiation causes genetic disorders.
26. What are age pyramids?
Ans. Age pyramids : Three ecological ages are:
# Pre-reproductive, Reproductive and Post-Reproductive
# High proportion pre-reproductive individuals occur in expanding population
# Pre-reproductive individuals are uniform in stable population.
# Pre-reproductive individuals are less in Declining population.
27. Differentiate b/w GIFT and ICSI.
Ans.
GIFT
ICSI
Intra cytoplasmic sperm
Called as gamete intra fallopian
transfer this is a special
transfer(b).transfer of ovum from a donor
female to provide suitable environment . technique to prepare embryo
in lab.
Sperm is not directly injected to ovum
The sperm is directly injected
to ovum.
No artificial insemination is done
Artificial insemination is done
for infertile couple
SECTION-D
28. How replication of DNA takes place in eukaryotes?
Ans. Replication of DNA In Eukaryotes Definition: "Process by which DNA produces daughter DNA
molecules which are exact copies of the original DNA." In eukaryotes, DNA is double stranded. The two
strands are complementary to each other because of their base sequences.
Semi-conservative method of DNA replication
Important points:
(i) Most common method of DNA replication.
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(ii) Takes place in the nucleus where the DNA is present in the chromosomes.
(iii) Replication takes place in the S-phase (synthesis phase) of the interphase nucleus.
(iv) Deoxyribose nucleotides needed for formation of new DNA strands are present in nucleoplasm. At the time
of replication, the two strands of DNA first separate.
Each strand then acts as a template for the formation of a new strand. A new strand is constructed on each
old strand, and two exactly identical double stranded DNA molecules are formed. In each new DNA
molecule, one strand is old (original) while the other is newly formed. Hence, Watson and Crick described
this method assemi-conservative replication. (A) An overall process of DNA replication showing replication
fork and formation of new strands template and lagging template.
29. Explain Hardy-Weinberg Principle.
Ans. Hardy-Weinberg principle: In population genetics, the idea that if a population experienced no
selection, no mutation, no migration, no genetic drift, and are random mating,then the frequency of each allele
and the frequencies of genotype in the population would remain the same (constant) from one generation to
the next generation.
p2 + 2pq + q2 = 1 or, (p + q)2 = 1
Calculation of allele frequencies Recessive traits:
If the frequency of a recessive trait such as cystic fibrosis or PKU is known, it is possible to calculate allele
frequencies and genotype frequencies using the Hardy Weinberg equation and its assumptions are as follows:
i. Say 1 in 1, 2500 Indian newborns have cystic fibrosis which means that the frequency of homozygotes for
this recessive trait is q² = 1/2,500 = 0.0004
ii. The square root of the frequency of recessives is equal to the allele frequency of the cystic fibrosis allele q =
(0.0004)0.5 = 0.02
iii. The frequency of the normal allele is equal to 1 - the frequency of the cystic fibrosis allele p = 1- q = 1 - 0.02
= 0.98105
iv. The frequency of carriers (heterozygotes) for the cystic fibrosis allele is 2pq = 2 (0.98)(0.02) = 0.04 or 1/25
v. The frequency of homozygotes for the normal allele is p² = (0.98)² = 0.96
vi. Thus the population is composed of three genotypes at the calculated frequencies of homozygous normal =
0.96, heterozygous carriers = 0.04, homozygous affected = 0.0004.
30. Differentiate between:Spermatogenesis and oogenesis.
Ans.
Spermatogenesis
Oogenesis
Produces male gametes (sperm).
Produces female gametes
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(oocytes).
Occurs in the seminiferous tubules
(in testes).
Occurs in the ovaries.
Involves meiosis –occurs throughout Involves meiosis occurs after
life after puberty.
puberty until menopause.
May produce 400,000,000 per day.
Humans normally produce one
oocyte during each ovarian cycle.
Primary spermatocyte divide equally Primary otocyte divide unequally to
to form two similar secondary
form one large secondary oocyte
spermatocytes.
and a small polar body.
One spermatogonium produces 4
functional spermatozoa.
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An oogonium produces one
functional ovum and 3 non
functional polar bodies.
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SECTION-A
1. How many chromosomes are in a gamete of an organism that has 46 chromosomes in its cells?
Ans. Gametes (n) have half the number of chromosomes found in the cells (2n). Hence, 2n = 46 then n = 23.
2. The mechanism to prevent the self pollen from fertilizing the ovules by inhibiting pollen germination
or pollen tube growth, on the pistil. What is that mechanism?
Ans. Self Incompatibility
3. What is Amniocentesis?
Ans. Foetal test based on chromosomal pattern in amniotic fluid surrounding the developing embryo. can be
used for sex determination.
4. What is pedigree analysis?
Ans. It is study of family history about inheritance of a particular trait, it is done for several generations.
5. Give the name of enzymes used for DNA replication.
Ans. DNA ligases, DNA helicase, DNA polymerase.
6. On examining a patient, he had a mass of proliferating cells damaging the neighbouring tissues
also. The doctor explained the disease to the patient. Name the disease and its property
Ans. Malignant tumour , Metastasis
7. Traditional hybridization procedures used in plant and animal breeding very often leads to inclusion
and multiplication of undesirable genes along with the desirable ones. What are the steps involved in
genetic engineering to over come this limitation?
Ans. (i) Gene cloning
(ii) Gene transfer
8. What are the advantages of Molecular diagnosis technique?
Ans. (i) Accurate Disease can be detected at very early stage.
(ii) Can be diagonised even if the number of pathogens is very low.
SECTION-B
9. When do implantation occurs?
Ans. The blastocyst is a liquid-filled ball of cells. Occurs around 5 – 8 days after conception. Implantation in the
endometrium occurs at this stage.
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10. What do you understand by term muations?
Ans. Mutations are changes in a genomic sequence: the DNA sequence of a cell''s genome or the DNA. They
can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses,
transposons and mutagenic chemicals, as well as errors that occur during meiosis or DNA replication.
11. What is disruptive selection?
Ans. Disruptive selection, like directional selection, favors the variants of opposite extremes over
intermediate individuals. Disruptive selection differs in that sudden changes in the environment creates a
sudden force favouring that In nature, sexual dimorphism is probably a common example.
12. Rahul was suffering from the malfunctions of kidneys and need a replacement. His friend comes
forward to donate him a kidney but after through examination the doctors refused to accept the kidney.
Why he was refused to donate and what is it that the doctors check?
Ans. He underwent blood group and tissue typing / matching because the body is able to differentiate between
self non self .Defense systems may generate cell mediated immune response.
13. What are symbiotic associations and state their advantages?
Ans. Symbiotic Associations Eg.Genus Glomus sp. form mycorrhiza Fungal symbiont absorbs phosphorus
from soil and passes it to plant. Plants show resistance to root – borne pathogens. Tolerance to salinity and
drought ,Increase in growth and development.
14. Give the principle of PCR.
Ans. PCR principle: PCR reaction is a DNA synthesis reaction that depends on theextension of
primers annealed to opposite strands of a dsDNA template that has been denatured (melted apart) at
temperatures near boiling. By repeating themelting, annealing and extension steps, several copies of the
original template DNA can be generated.
15. In oogamous organisms, female gamete is large and non-motile but the male gamete is very small.
Why such type of adjustment is there in higher organisms?
Ans. Female gamete is large and non motile, is an adaptation for storing more food which will be required for
the future development. The male gamete has to move to reach the counterpart, so it has the machinery for its
reaching and delivering the chromosomes. It is therefore both the gametes have specialized themselves for
their functions.
16. Give the scientific term for the process of copying genetic message from one strand of DNA into
RNA. Only one strand of DNA is used during transcription. Why?
Ans. Transcription
If both are copied they would code for m-RNA molecules with different sequences, hence different proteins will
be formed from same DNA sequence. If two strands of m-RNA are produced simultaneously they would coil
being complementary to each other.
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17. State the process of bio-gas production?
Ans. In a concrete tank which is 10- 15 mts deep, the slurry of bio-waste or cow/buffalo dung is fed.
Methanogens work on it, i.e. carry out ferementation.Floating cover placed above the gas holder tank,it rises
as biogas content rises. Connecting pipe is there to supply biogas.
18. What are the factors that affect population growth?
Ans. Factors that affect the size of population
Food availability
Weather
Predation pressure
Competition Density of population at any time at a given place depends on Natality, Mortality, Emigration
Immigration
SECTION-C
19. What is the difference b/w endometrium and myometrium?
Ans.
Endometrium
Myometrium
It is innermost glandular layer that
lines the uterine cavity
It is the middle thick layer of smooth
muscles of the uterine wall.
Implantation occurs in this layer
It is responsible for the uterine
movement.
It undergo cyclic changes during
the menstrual cycle
It does not undergo
any cyclic changes during the
menstrual cycle
20. How ZW sex determination system differs from XY?
Ans. The ZW sex-determination system is found in birds, reptiles, some insects and other organisms. The
ZW sex-determination system is reversed compared to the XY system: females have two different kinds of
chromosomes (ZW), and males have two of the same kind of chromosomes (ZZ).
21. “Giraffes who in an attempt to forage leave on tall trees had to adopt by elongation of their necks.”
Make use of this statement to enumerate the main points of Lamark’s theory and Darwin’s theory of
Natural selection.
Ans. In order to eat leaves of tall trees, Giraffe had to adapt by stretching (elongation) of their neck i.e.
evolution is driven by use & disuse of organs (Lamarckism) main points of theory to be incorporated.
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Variant Giraffes with an ability to elongate the neck were already there in the crowd of giraffes & linking of it
to explain main points of Darwin’s theory of natural selection.
22. How r-DNA is used in Diagnosis of diseases?
Ans. Genetic diagnosis
a. Diagnosing inherited disorders * Cystic fibrosis * Muscular dystrophy * Haemophilia A and B * Sickle cell
anaemia
b. Diagnosing cancer - certain cancers are caused by specific and reproducible mutations: e,g. Retinoblastoma
- childhood cancer of the eye. The heritable form (germ line mutation of one of the two retinoblastoma allelles):
mutation is detected in all cells. Spontaneous form: only detected in tumour tissue.
c. Blood group typing d. Prenatal diagnosis – eg determining the sex of foetus for those at risk of X-linked
disorders PCR is one of the most versatile techniques invented.
23. Since the origin of life on earth and evolution there have been 5 episodes of mass extinction, but
the current rate of extinction is 100-1000 times. What are the main causes of high extinction rate and
how is it going to harm human beings?
Ans. Human activities are the basic cause for it.
Causes – 4 major causes (The evil Quartet along with suitable examples of each:(i) Habitat loss and fragmentation-decline in covered forest area from 14% to 6%.
(ii) Overexploitation- extinction of steller’s sea cow
(iii) Alien species invasion-Nile perch introduction into Lake Victoria resulted in extinction of 200 species cichlid
fish.
(iv) Co-extinction-coevolved plant pollinator mutualism.
Harms:
(a) Decline in plant production.
(b) Lowered resistance to Env. Perturbations like drought.
(c) Increased variability in certain ecosystem processes such as plant productivity,water use etc.
24. What are the basis to decide on biodiversity conservation?
Ans. Biodiversity conservation: Reasons for conservation can be grouped into three categories:
(a) Narrow utilitarian-for deriving direct economic benefit from nature.
(b) Broad utilitarian-as biodiversity plays a major role in many ecosystem services.
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(c) Ethical-we need to realise that every species has an intrinsic value and we need to pass on our biological
legacy to future generations.
25. Explain in details the process of STP.
Ans. Treatment is done in two stages.
Primary : Physical removal of particles large and small by filtration and sedimentation. Solids so left makes
primary sludge and the Supernatant becomes effluent.
Secondary: Primary effluent taken to large aeration tanks. Agitated mechanically and air pumped into it.
Aerobic microbes form masses with fungal filaments known as flocs.
Microbes consume organic matter in effluent for growth, thus BOD ( Biological oxygen demand) reduced.
Then it is passed into settling tank.
Bacterial flocs get sedimented , a small portion is kept to activate the sludge. Small part of activated sludge
used as inoculums in aeration tank and major part is pumped into large anaerobic sludge digesters
Anaerobic bacteria digest bacteria and fungi. Bacteria produce gases such as menthane, hydrogen sulphide
and CO2 – Biogas. And then secondary effluent is released into rivers and streams.
26. Define the following terms :
(a) Acrosome
(b) Amniotic sac
(c) Birth
(d) Parturition Blastocyst
(e) Cervix
(f) Clitoris
(g) Coitus
Ans. Acrosome- the part of a sperm cell that contains an enzyme – (This enables a sperm cell to penetrate an
egg.) Afterbirth-placenta and fetal membrane expelled from the uterus after the birth of a baby
Amniotic sac-fluid-filled membrane or sac that surrounds the developing embryo while in the uterus.(protects
baby from hard shocks, keeps it at a constant temperature. )
Birth-the process of being born. process by which baby moves from the uterus into the outside world.
Parturition Blastocyst = blastula = early stage of an embryo; a liquid-filled sphere whose wall is composed of
a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus
occurs
Cervix- lower part, or neck, of uterus. (Opening to the uterus.)
Clitoris-small, sensitive organ in front of the vagina
Coitus-synonym for sexual intercourse
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27. Write the scientific name of the organism that T.H.Morgan selected for his experiment . Why did he
choose this organism ?
Ans. Drosophila melanogastar
Reasons
(a) could be grown on simple synthetic medium in the laboratory
(b) Short life cycle.----two weeks
(c) single mating could produce a large number of progeny flies
(d) clear differentiation of sex .
(e) has many types of valuation
SECTION-D
28. Give the process of DNA replication in details.
Ans. The various steps involved in this process are summarized as follows:
i. Mechanism of replication starts at a specific point of the DNA molecule, calledorigin.
ii. At origin, DNA strand breaks because of an incision (nick). This is made by an enzyme called incision
enzyme (endonuclease).
iii. The hydrogen bonds joining the two strands are broken by the enzyme.
iv. The two strands start unwinding.
This takes place with the help of a DNA unwinding enzyme Helicases. Two polynucleotide strands are thus
separated.
v. The point where the two strands separate appears like a fork or a Y-shape. This is described as
a replicating fork.
vi. A new strand is constructed on each old strand. This takes place with the help of a small RNA
primer molecule which is complimentary to the DNA at that point.
vii. Each old DNA strand acts as a template (site) for the construction of new strand. The RNA primer attaches
itself to the old strand and attracts the enzymes(DNA polymerase III) which add new nucleotides
through base complementation. The deoxyribose nucleotides are present in the surrounding nucleoplasm.
New DNA strand is thus constructed opposite to each old strand
viii. Formation of new complementary strand always begins at the 3'' end of the template strand (original
strand) and progresses towards the 5'' end (i.e in 3'' - 5'' direction). Since the new strand is antiparallel to the
template strand, it is obvious that the new strand itself is always developed in the, 5''-3'' direction. For this
reason when the two original strands separate (then with respect to the origin of separation), one acts as 3''-5''
template while the other acts as 5''- 3'' template.
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ix. Of the two, the replication of 3''-5'' template begins first. Hence the new strand formed on it is called
the leading strand. The other template (5''-3'') must begin replication at the fork and progress back toward the
previously transcribed fragment. The new strand formed on it is called the lagging strand.
x. Replication of the lagging strand takes place in small fragments called Okazaki fragments. These are then
connected together by the enzyme ligase.
xi. Replication may take place in only one direction on the DNA helix (unidirectional) or in two directions
(bidirectional).
xii. At the end of the process, two double stranded DNA molecules are formed from the original DNA molecule.
29. Describe various stages of fertilisation which leads to implantation,with the help of a well labelled
diagram.
Ans.
30. What is the difference b/w convergent and divergent evolution.
Ans.
Divergent evolution
Convergent evolution
Origin of a variety of species from a Independent development of similar
common ancestral form.
forms and features by unrelated
organisms to adapt to a similar
environment.
Divergent evolution is the process of Unrelated species become more
two or more related species
and more similar in appearance as
becoming more and more dissimilar. they adapt to the same kind of
As they adapted to different
environment.
environments, the appearance of the
two species diverged.
Homologous organs supports it.
Analogous organs supports it.
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