Education is the key to success • 247 .
CHAPTER - 1
THE LIVING WORLD
•
The living world comprises of diverse
type of organisms.
•
Growth
•
Biology is the branch of science which
deals with the study of living things. Ar-
istotle is considered as the founder of
growth.
•
•
•
Increase in mass
The term biology is proposed by Lamarck.
Increase in number
Biology is divided into 2 main branch-
Multicellular organisms –grow by cell di-
es—Botany and Zoology.
vision.
Botany is a Branch of biology which
•
Aristotle is considered as the “father of
•
ter, cell division is seen in certain tissues
Theophrastus is considered as the
to replace the lost cells.
“father of botany”. He was a student of
•
Aristotle.
•
•
These non living objects are grown by the
living things from non living things.
accumulation of material on their surface.
Characteristics of living organisms.
Therefore growth cannot be taken as a
defining property of living organisms
Basic characteristics exhibited by living organ-
alone. A dead organism does not grow
isms are growth, reproduction, ability to
ganization, and consciousness.
Non living objects such as mountains,
boulders, sand mounds, etc also grow.
Life is the property that distinguishes
sense environment. Metabolism, cellular or-
Unicellular organisms also grows by cell
division. .
There are 2 types of objects in the world
living and non living.
•
In animals, the growth by cell division
occurs only up to a certain age. Thereaf-
zoology”.
•
In plants, growth by cell division occurs
throughout their life span.
deals with the study of plants.
•
Growth of an organism has two characteristics.
biology.
•
Increase in body mass considered as
Reproduction
•
It is a characteristic of living organisms. In
living organisms, reproduction means the
Plus 1 Biology
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The Living World
There is no substitute for hard work • 248 .
•
production of new individuals similar to the
and respond to these environmental stimu-
parents.
li. Which could be physical, chemical and
biological.
A multicellular organism reproduces by 3
ways—sexual, asexual and vegetative,
method.
Examples:•
Examples
Human beings sense the environment
through sense organs.
•
Fungi—asexual spores
•
Hydra and yeast—budding
•
Planaria—regeneration
•
Plants respond to external factors like
light, temperature, water, pollutants,
other organisms etc.
•
•
Filamentous
algae
&
fungi—
( duration of light) affects the reproduction
fragmentation.
•
In both plants and animals, photo period
in seasonal breeders.
In unicellular organisms like bacteria,
•
A human being is the only organism hav-
amoeba, unicellular algae etc reproduction
ing ” selfconsciousness” ie aware of him-
is synonymous with growth, ie increase in
self…therefore
number of cell.
•
Metabolism
•
the livingorganisms.
The sum total of all the chemical reactions
•
sharing of common genetic material to
Metabolism is a defining feature in all liv-
varying degree.
ingorganisms.
Diversity in the living world
Cellular organization
•
All unicellular or multicellular organisms
•
life in the world.
Cellular organisaton of the body is the
defining feature of life forms.
•
Biodiversity.
All living organisms have the ability to
sense their surroundings or environment
Plus 1Biology
This natural diversity of life on earth is
generally called biological diversity or
Consciousness
•
All living organisms which live on earth
together make up the natural diversity of
are madeup of one or more cells.
•
All living organisms (present , past and
future) are linked to one another by the
occuring in our body is called metabolism.
•
consciousness is the defining property of
TAXONOMY
•
The branch of science which deals with
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Always have an attitude of gratitude • 249 .
identification, nomenclature and classifica-
•
Anyone can study, describe, identify and
tion of organisms is called taxonomy or
give a name to an organism provided cer-
systematics.
tain universal rules are followed
NOMENCLATURE
•
These rules codes) are framed and stand-
•
Method of naming is called nomenclature.
•
Naming of living organisms is one of the
ICBN- International Code for Botanical
important features of taxonomy.
Nomenclature
•
Names may be of 2 types.
ICZN- International Code for Zoological
Local names and scientific names.
Nomenclature
1)
Local names
•
ardized by the following organizations.
Biological names are generally in Latin and written in italics. They are
Locally used names are called local names
latinised or derived from Latin irre-
( vernacular names or common names)
spective of their origin.
•
These names vary from place to place.
•
These names created confusion because
the genus whereas second one is for
different species may be known by the
species.
same name.
2)
3)
to indicate their latin origin.
It is a method of naming by which an organism is known by a scientific name having 2 components (words).
•
4)
Generic name starts with a capital let
ter and the specific name with a small
letter
It was first introduced by Carolus Linnaeus
.
in1758
•
Names are printed in italics or when
hand written are separately underlined
Binomial nomenclature
•
First word of a biological name denotes
Eg:- Mangifera indica, Homo sapiens.
In a binomial name, the first component
(word) is called generic name or genus
5)
The name of the author is written in ab
name and the second component (word) is
breviated form after the species name
called specific name or species name.
and is printed in roman.(eg: Mangifera
indica Linn.) it indicates that this spe
cies was first described byLinnaeus.
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Be the light for your family • 250 .
Classification
•
Taxonomic categories
It is the process by which anything is
•
Plants and animals are placed in a series or
grouped intoconvenient categories based
succession of different ranks or categories
on some easily observable characters.
according to their natural relationship
Biological classification
Taxonomic hierarchy (hierarchy of
The scientific method of an arrangement
of organisms into groups is called biological
classification.
categories)
•
It is a system of classification in which a
group of things are ranked one above the
Taxonomy
other. In this system seven taxonomic categories are placed one above the other.
•
It is a branch of biology which deals with
identification, nomenclature and classifi-
The categories are..
cation of organisms.
•
Taxonomy is based on…
•
Kingdom, phylum or division, class, order,
family,genus and species.
Characterisation
Taxon :- each category in the taxonomic hier-
•
archy is called a taxon. It represents the
Identification
actual biological objects placed in a cate•
Classification and
•
Nomenclature
gory.
The modern taxonomic studies are based on
•
External and internal structure
•
Structure of cell
•
Developmental processes
•
Ecological information
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Seven taxonomic categories.
•
genus Felis which includes cats.
Species
It is a group of individuals resembling one another in all major vegetative and reproductive
characters (A species is a group of individuals
Family
•
isolated andsimilar in morphological character-
A family is an assemblage of related genera.Examples:
which are genetically distinct, reproductively
•
istics).
•
The genus Panthera differs from another
The lion (Panthera leo) and the house
cat (Felis domestica) belonging to two
different genera are included under the
It is the lowest taxon in biological classi-
family Felidae.
fication.
Order or cohort
•
E g: - Mangifera indica (Mango)
Solanum tuberosum (Potato)
•
An order is a category of related families.
•
Example families like Felidae (lion, tiger,
Panthera leo (Lion)
•
•
leopard,cat etc.) and Canidae (dogs and
The names indica, tuberosum and leo
represents specific names.
The names Mangifera, solanum and panthera represents generic names.
foxes) are placed under the order carnivora.
•
Plant families like Convolvulaceae and
Solanaceaeare included in the order poly-
•
The scientific name of human being- Homo sapiens
Genus
moniales.
Class
•
•
Several related orders having certain common characters form a higher category
A genus is a group of related species.
called the class.
•
All the species in a genus have many common characteristics. For example, the genus panthera includes species such as lion
•
Example the order carnivora and the order
primata are included in the clas Mammalia
(Panthera leo), leopard (Panthera pardus), and tiger (Panthera tigris) with
many common features.
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Phylum or Division
•
Herbarium
Classes having same features in common
A herbarium is defined as store house of col-
constitute a phylum.
lected plant specimens which have been dried,
pressed, preserved on herbarium sheets, and
•
For example phylum chordata include a
arranged in the sequence of a universally ac-
number of classes such as pisces, am-
cepted system of classification.
phibia, reptilia, aves and mammals.
•
The herbarium sheets also carry a label provid-
The classes such as Dicotyledonae, mono-
ing information about date and place of col-
cotyledon, are included in the division of
lection.
Angiospermae.
English, local and botanical names, family,collectors name etc..
Kingdom
Herbarium label
The highest category in the biological clas-
•
sification is the kingdom. It includes one
or more related divisions or phyla.
Plants are kept in a kingdom plantae and
•
animals are put in the kingdom animalia.
Com-
Biolog-
mon
ical
Name
Name
Man
Homo
Genus
Musca
fly
domes-
Order
Class
Phylum /
Division
Homo
saplens
House-
Family
Hom-
Primata
inidae
Musca
Musci-
Mamm
Chordata
alta
Diptera
Insecta
Arthropoda
•
dae
is published in the form of a book called
tica
Mango
Man-
Man-
Ana-
Sapin-
Dicoty-
gifera
gifera
cardiac
dales
ledonae
indica
Wheat
Triti-
Poace-
cum
cum
ae
aes-
flora.
Angiospermae
eous
Triti-
Information about the collected specimens
•
Poales
Mono-
It gives a list of total plant species in a particular region together with a brief descrip-
Angiospermae
cotyled
tion of the same.
on
tivum
•
Plus 1 Biology
The largest herbarium of the world is Her-
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Today a reader, Tomorrow a leader • 253 .
barium of royal botanical garden at
Kew in England.
•
Manuals
These provide an information for identification
The largest herbarium in India is central
national herbarium.
of names of species occurring in an area.
Monograph
Taxonomic keys
These provide the information of any one tax•
A key is a tool by which each species in a
group of organisms may be identified.
•
It is prepared by a taxonomist to help other
biologists to identify the species.
•
Catalogue
These provide the list of publications. The
publications publish the books, periodicals and
Taxonomic keys are based on contrasting
characters.
•
on.
dictionaries which provide new information
for taxonomic studies
IMPORTANT QUESTIONS
The characters are in a pair called couplet.
1.
•
Separate taxonomic keys are required for
ICZN and ICBN
each taxonomic category like family, genus and species for their identification
•
Expand the following terms.
2.
The scientific name of housefly and
wheat are given below. Correct them.
Besides the above mentioned taxonomic aids , flora, manuals, monographs
(a) Musca Domestica
and catalogues also serve as taxonomic
tivum
aids for correct identification.
3.
(b) Triticum Aes
Select a proper genus and species name
in order to get correct scientific name of
Flora
the following animals from the table giv
en below.
•
These contain the actual account of habitat
and distribution of plant species of a given
area.
•
It provides the index to plants occuring in
a particular area.
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4.
Generic
Species
name
name
Mangifera
Sapiens
Panthera
Indica
Musca
Leo
Homo
domestica
PREVIOUS YEARS QUESTIONS
9. Align the taxonomic categories in the
acending order.
Genus, Order, Phylum, Species, Family,
Class, Kingdom.
List the advantages of the following:
10.
(a) Taxonomic key (b) Herbarium
5.
Complete the table using suitable terms.
Com-
Complete the table.
mon
Genus
Species
Class
Phylum
Name
Sl. No.
1.
Common Biologiname
cal name
……...
Panthera
Class
6.
Mango
…...
Sapi-
Mam- ——
11. Rearrange the following taxonomic cate
…...
gories
in
the
correct
sequence.
Kingdom  Class Phylum Genus
Fill in the blanks .
Family Order Species
Species → ……. (a)…...→Family →
Order ……(b)….. Phylum → Kingdom.
7.
——
…...
leo
2.
Man
12.
Binomial nomenclature was proposed
by…….
Panthera leo
(a) Identify the naming system used.
13.
Unit of classification is……….
(b) What do the two terms indicate?
8.
The Hierarchical arrangement of taxo
nomic category of housefly is given be
low. Rewrite it correctly.
(a) Taxon
(b) Species
(c) Genus
(d) cell
ANSWERS
Muscidae → Diptera → Musca → Insec
ta → domestica → Arthropoda →
1.
ICZN - International Code of Zoological
Nomenclature.
ICBN - International Code of Botanical
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Nomenclature.
2.
(a) Musca domestica
5.
(b) Triticum aes-
tivum
Sl. No.
Common Biologiname
3.
1.
Generic
Lion
Species
cal name
Panthera
Mango
Man-
Dicotyledonae
Mangifera
indica
gifera
Panthera
leo
indica
Musca
domestica
Homo
sapiens
6. (a) Genus
Carnivora
Leo
2.
Class
(b) Class
7. (a) Binomial nomenclature
4. (a) 1. Each species in a group of organisms
(b) Genus and species
8. Domestica → Musca → Muscidae → Dip-
may be identified.
2. To help other biologists to identify the
species.
tera → Insecta → Arthropoda
9. Species → Genus → Family → Order →
(b) 1. It serves as quick referral system in
taxonomic studies.
Class → Phylum → Kingdom.
10. Homo, Chordata
2. It is a permanent and ready record of
plant specimen.
11. Kingdom  Phylum  Class  Order
 Family  Genus  Species.
3. It is used for knowing our bio - re
sources and biodiversity.
12.Carolus Linnaeus
13. Taxon
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CHAPTER 2
BIOLOGICAL CLASSIFICATION
Classification:- The arrangement of anything
eukaryotes and prokaryotes
into groups is called classification.
ii) It does not distinguish between unicellular
Biological classification:- the scientific method of arrangement of organisms into groups is
called biological classification.
•
organisms and multicellular organisms.
iii) It does not distinguish photosynthetic
organisms (eg: green algae) and nonphotosynthetic organisms (eg: fungi).
Aristotle was the first to attempt a scientific classification of organisms.
•
Based on morphology (external character-
iv) Included bacteria, blue green algae, and
fungi in Kingdom Plantae along with oth-
istics) he classified plants into three
er plants because of the presence of cell
groups-trees, shrubs and herbs.
•
wall. But bacterial cell wall, plant cell wall
He classified animals into two categories
and fungal cell wall differ from each other
red blooded and non-red blooded
in their constitution.
v)
Two kingdom classification
•
into either of the categories of the two
kingdom classification.
Carolus Linnaeus proposed the two kingdom classification and the classification
was used till recently.
•
A large number of organisms did not fall
Five kingdom classification
In 1969, R.H. Whittaker proposed the five-
According to this system organisms are
kingdom classification. He classified the living
classified into two large groups
organisms into five kingdoms. The criteria
used by Whittaker are given below.
(i) Kingdom plantae (Plant Kingdom)
(i) Kingdom Animalia (Animal Kingdom)
Drawbacks of the Two Kingdom
Classification
i)
The system did not distinguish between
Plus 1 Biology
•
Cell structure
•
Thallus organisation
•
Mode of nutrition
•
Reproduction
•
Phylogenetic relationships
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Biological Classification
Whatever you are, be a good one • 257 .
The five kingdoms of living organisms are
given below.
1.
Kingdom Monera
2.
Kingdom Protista
3.
Kingdom Fungi
isms.
2. Kingdom Protista
•
unicellular aquatic eukaryotic organisms.
•
4.
Kingdom Plantae
5.
Kingdom Animalia
The Kingdom Protista includes primarily
The cells of protists have true nucleus and
other membrane-bound organelles and non
membraneous organelles
Different characteristics of the five kingdoms
3.
Kingdom Fungi
•
The Kingdom Fungi includes eukaryotic,
multicellular,
heterotrophic
organisms
(Yeast is an exceptional fungus which is
unicellular).
4.
Kingdom Plantae
•
The Kingdom Plantae (plants) includes
multicellular, chlorophyll-containing organisms.
•
They are immobile (No locomotion), cell
wall is composed of cellulose.
5.
Kingdom animalia
•
It includes multicellular heterotrophic eukaryotes. They show locomotion. Cells
1. Kingdom Monera
•
are without cell wall.
All prokaryotic organisms are included in
Merits of five kingdom classification
the kingdom monera.
1.
This classification is based on cellular
•
They are microscopic organisms.
•
True nucleus and other membrane-bound
characters which evolved very early in
cell organelles are absent in these organ-
the organic world.
Plus 1 Biology
organisation and modes of nutrition, the
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Biological Classification
There is no substitute for hard work • 258 .
2.
In this classification, the organisms are
placed based on the gradual evolution of
early organisms into plants and animals.
3.
All prokaryotic organisms are grouped
otes.They are divided into three groups.
1.
Halophiles-bacteria living in salty areas
2.
Thermoacidophiles-They are temperature
and acid loving bacteria and live in hot
together under Kingdom Monera
4.
The eukaryotic unicellular organisms are
grouped under Kingdom Protisa.
5.
springs.
3.
Methanogens-found in marshy areas and
in the guts of several ruminant animals
Green plants have cellulosic cell wall
like cows and buffalos. They are responsi-
(cell wall with cellulose) while fungi
ble for the production of methane (biogas)
have chitinous cell wall (cell wall with
from the dung of these animals.
chitin), Green plants are autotrophs while
fungi are heterotrophs. Based on these
Eubacteria (True bacteria)
differences, the fungi were placed in a
separate kingdom - Kingdom Fungi,
and cyanobacteria.
KINGDOM MONERA
•
They are true bacteria which include bacteria
They are unicellular microscopic and
(i) Bacteria
prokaryotic
•
They lack definite nucleus and membrane
bound organelles.
•
They are unicellular microscopic monerans.
Based on their shape, bacteria are grouped into
4 categories - Coccus, Bacillas, Vibrium and
Rigid cell wall present (made of polysac-
Spirillum
charides and aminoacids)
1. Coccus ( cocci)-Spherical shaped bacte-
•
Nutrition-heterotrophic or autotrophic
•
Bacteria are the sole members of this
in pairs (eg: Diplococcus) or in groups(eg:
kingdom.
staphylococcus)
Monerans are classified into three groups.
(i) archaebacteria (ii) eubacteria (iii) mycoplasma
rium. It may occur singly (eg: Monococcus) or
or
in
long
chains
(streptococcus).
2. Bacillius ( bacilli) - Rod-shaped bacterium.
It may occur singly ( Bacillus) or in pairs(eg:
Diplobacillus) or in groups (eg: Streptobacil-
Archaebacteria
lus).
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Biological Classification
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3.
Vibrium (vibrio) - Comma-shaped bacte-
Heterotrophic bacteria
rium. eg: Vibriocomma.
They do not synthesise their own food but
4.
Spirillum ( spirilla) - Spiral-shaped bacte-
rium. It is spirally twisted or coiled. eg: Spiro-
depend on other organisms or on dead organic matter for food.
chetaes.
Heterophic bacteria may be of 3 types parasitic bacteria, saprophytic, and symbiotic bacteria.
Parasitic bacteria: They absorb food from the
host and cause diseases on the host.
eg: Cholera, typhoid, tetanus, citrus canker are
diseases caused by bacteria
Saprophytic bacteria: They live on the dead
Nutrition in Bacteria
matters and absorb food from them.
Nutrition may be Autotrophic or heterotrophic.
ficial association with other organisms. eg:
Autotrophic bacteria
Rhizobium.
They synthesise their own food from inorganic substances,bacteria may be divided into
2 types-photosynthetic autotrophic bacteria
and chemosynthetic autotrophic bacteria.
i)
Symbiotic bacteria: They form mutually bene-
Reproduction in bacteria
•
Reproduction mainly by binary fission
•
Under unfavorable conditions they produce
Photosynthetic autotrophic bacteria.
spores.
They prepare theirown food from the en•
ergy obtained from the sunlight.
Sexual reproduction is seen in some species through a primitive type of DNA
ii)
Chemosynthetic autotrophic bacteria
transfer from one bacterium to another.
They oxidise various inorganic substances such as nitrates,nitrites and Ammonia
(ii) Cyanobacteria (blue-green algae)
to release energy for their ATP produc-
1. They may be single-celled (eg: Spirulina),
tion.
Plus 1 Biology
colonial (eg: Nostoc) or filamentous (eg:
Winner’s Coaching Centre
Biological Classification
Be giving, enjoy sharing • 260 .
Oscillatoria).
saprotrophic.
2. Colonial forms of cyanobacteria are gener-
•
The kingdom Protista is classified in to
ally surrounded by a mucilaginous sheath
chrysophytes, dinoflagellates, euglenoids,
(gelatinous sheath). It prevents drying of
slime moulds and protozoans,
the cells during desiccation. eg: Nostoc.
3. They have chlorophyll-a pigment similar to
1. Chrysophytes
that of green plants.
4. They are aquatic or terrestrial
5. They form blooms in polluted water bod-
•
Found in fresh water and in marine habitat.
•
Microscopic and float
passively in water cur-
ies.
rents(Planktons)
6. Some of the species possess specialised
cells called Heterocysts.
7. Heterocysts help to fix atmospheric nitro-
•
Most of them are photosynthetic.
•
Diatoms and desmids are the major
groups.
gen and enrich the fertility of the soil. eg:
Diatoms
Nostoc and Anabaena.
Mycoplasma
•
They are the smallest living cells on earth.
•
They lack cell wall and can survive with-
•
They are the chief producers in the ocean.
•
Walls are embedded with silica and so
the walls are indestructible.
•
out oxygen.
•
Diatoms have left behind large amount of
cell wall deposits in their habitat. This is
known as diatomaceous earth.
They cause many pathogenic diseases in
•
plants and animals.
Diatomaceous earth is granular in nature, so it is used in polishing, filtration
KINGDOM PROTISTA
of oils etc.
•
Unicellular, Aquatic, Eukaryotes.
2. Dianoflagellates
•
Often they may possess flagella or cilia
•
•
Cell wall, if present, made of cellulose
•
Nutrition: Photosynthetic, holotrophic or
Plus 1 Biology
They are mostly marine and photosynthetic.
•
They appear yellow, green, brown, blue or
red in colourd
Winner’s Coaching Centre
depending on the major
Biological Classification
Make time for yourself • 261 .
pigment present in their cells.
leaves engulfing organic material.
The cell wall contains a stiff cellulose plate on
•
the outer surface.
They form an aggregation called plasmodium under suitable conditions.
Most of them have two flagella one longitudi-
•
nal and other transverse.
Under unfavorable conditions the Plasmodium differentiates and forms fruiting bodies. The fruiting bodies bear spores at their
Red dianoflagellates (eg: gonyaulax) multiply
tips.
rapidly and make the sea appear red (red tides).
During red tide they release toxins into the sea
5. protozoans
result in the death of large number of marine
animals such as fishes.
•
or parasites.
3. Euglenoids
•
Majority of them are fresh water organ-
•
•
They have a protein rich layer called the
•
Amoeboid protozoans, flagellated protozoan,
makes their body flexible.
ciliated protozoan, sporozoans.
They have two flagella, one short and the
They are photosynthetic in the presence
KINGDOM FUNGI
•
under deprived sunlight predating other
Eukaryotic, unicellular (eg: Yeast) or multicellular,without chlorophyll.
of sunlight but behave like heterotrophs
•
small organisms.
•
There are 4 major groups of protozoans.
pellicle instead of cell wall. The pellicle
other long.
•
They are believed to be primitive relatives
of animals.
isms found in stagnant water.
•
All are heterotrophs and live as predators
Heterotrophic nutrition (Saprobes or Parasites)
The photosynthetic pigments in eugle-
•
noids are identical to that of higher
The body of the fungus is called mycelium.
plants. Example: Euglena.
4. Slime Moulds
A part of the mycelium is called hypha
•
The hyphae are septate (with cross walls)
or aseptate (without cross walls).
•
They are saprophytic protists..
•
The body moves along decaying twigs and
Plus 1 Biology
•
•
Fungi are multicellular (except yeast uni-
Winner’s Coaching Centre
Biological Classification
Dedication is expensive than talent • 262 .
cellular). Many fungi are multinucleate.
Sexual reproduction
The multinucleate condition is said to be
The sexual cycle of fungi has 3 steps.
coenocytic.
•
The cell wall is made up of chitin and polysaccharides.
Plasmogamy: fusion of protoplasm between 2
motile or non-motile gametes.
Karyogamy: Fusion of 2 nuclei.
•
Fungi are the major decomposers.
Meiosis: Zygote undergoes meiosis to form 4
haploidspores.
Nutrition in Fungi
•
Mostly they are heterotrohpic in nutrition
•
They absorb soluble organic matter from
dead substrates. So they are called sapro-
•
•
•
Kingdom fungi is classified into phycomycetes, ascomycetes, basidiomycetes and deuteromycetes
phytes.
Phycomycetes
Some depend on living plants and animals
•
Found in aquatic habitats and on decaying
for their food.They are parasites.
wood in moist and damp places or as obli-
Some fungi live in symbiotic association
gate parasites on plants.
with algae called lichens.
•
Mycelium is aseptate and coenocytic
Some are symbiotic with roots of higher
•
Asexual reproduction takes place by mo-
plants called mycorrhiza.
tile zoospores or by non motile aplanospoes.
Reproduction
•
•
•
ospores.
Zygospores are formed by fusion of two
gametes.
•
The gametes are similar in morphology
(isogamous) or dissimilar
Sexual reproduction - by oospores, ascospores and basidiospores.
•
•
Asexual reproduction - by different
spores like conidia,sporangiospores or zo-
•
in sporangium.
Vegetative reproduction takes place by
fragmentation,fission and budding.
These spores are endogenously produced
•
Examples: Rhizopus (the bread mould),
Mucor.
All the spores are produced in various distinct spore bearing structures called fruit-
•
Albugo is a parasitic fungus on mustard.
ing bodies.
Plus 1 Biology
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Ascomycetes
of different strains. Sex organs are absent.
•
It is commonly known as sac-fungi.
•
They are unicellular or multicellular. Yeast
(Saccharomyces) is a unicellular ascomycete.
•
•
dikaryon, which ultimately gives rise to a
club shaped structure called basidium.
•
Karyogamy and meiosis occur in the basidium resulting in the production of four
Conidia are the asexual spore. They are
produced exogenously on the special mycelium called conidiophores.
basidiospores.
•
The basidiospores are exogenously produced on the basidium.
•
Conidia germinate to form new mycelium
•
Sexual spores are ascospores. They are
produced endogenously in sac like asci.
The asci are arranged in different type of
•
Examples: Aspergillus,Claviceps,
•
Example: Agaricus (mushroom). Ustilago (smut),Puccinia (rust fungus).
Deuteromycetes
•
Neurospora,penicillium, yeast.
The basidia are arranged in the fruiting
body called basidiocarp.
fruiting bodies called ascocarps.
•
The fusion of somatic cells results in
They are known as imperfect
fungi because only the asexual or
Basidiomycetes
vegetative phases are known.
•
It includes Mushrooms, bracket fungi and
puff balls.
•
•
•
When sexual (perfect) stage of
the members of deuteromycetes
is discovered, they will be placed
They inhabit soil, logs and tree stems.
in ascomycetes or basidiomy-
Parasitic forms are rusts and smuts in liv-
cetes.
ing plants
•
Reproduce only by asexual spores called
•
The mycelium is branched and septate.
•
The asexual spores are not found.
•
Mycelium is septate and branched.
•
Vegetative reproduction is by fragmenta-
•
Some are Saprophytes or parasites. Eg:
tion.
•
conidia.
Alternaria, Trichoderma etc.
Sexual reproduction is brought about by
fusion of two vegetative or somatic cells
Plus 1 Biology
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Biological Classification
You are good enough, respect yourself • 264 .
KINGDOM PLANTAE
•
fat.
They are multicellular chlorophyll con-
•
They show locomotion.
•
The sexual reproduction is by copulation
taining autotrophic organisms.
•
They are eukaryotes
•
They have cellulose cell wall
•
Cells have large vacuole in the cytoplasm
VIRUSES
•
They are immobile (no locomotion)
•
Viruses are non cellular organisms
•
Most of the members are photosynthetic.
•
They were discovered in 1892 by Russian
•
A few members are partially heterotrophic
of male and female followed by embryological development
such as insectivorous plants (bladder wort,
biologist Iwanovsky
•
consists largely of proteins.
Venus fly trap) or parasites (Cuscuta).
•
Includes algae, Bryophytes, Pteridophytes,
Viruses could be crystallised and crystals
•
Viruses did not find a place in classification since they are not truly 'living'. They
Gymnosperms and Angiosperms.
are inert outside their specific host cell.
•
•
The life cycle of plants has two distinct
Viruses are obligate parasites. Viruses
phases - the diploid sporophytic phase
share characteristics of both living and
and the haploid gametophytic phase.
non-living things.
Both the phases alternate with each other.
Structure of viruses
The phenomenon is called alternation of
•
generations.
protein coat called capsid and genetic ma-
KINGDOM ANIMALIA
•
terial (DNA or RNA).
They are multicellular heterotrophic eu-
•
karyotes.
Capsid - The protein coat of virus is called
capsid.
•
The cells are without cell wall
•
They lack chlorophyll
•
Holozoic mode of nutrition
•
Reserve food in the form of glycogen or
Plus 1 Biology
A virus is a nucleoprotein. It consist of a
•
Genetic material - The genetic material is
either RNA orDNA.
•
Bacteriophages - Viruses which infect the
bacteria are called bacteriophages. They
have double stranded DNA as genetic ma-
Winner’s Coaching Centre
Biological Classification
Practice makes progress • 265 .
terial.
Diseases caused by viruses
Viruses cause diseases like mumps, small
pox, herpes,Influenza and AIDS.
Viroid - In 1971 T.O. Diener discovered a
new infectious agent that was smaller than
viruses and caused Potato spindle tuber
disease. It was found to be a free RNA
without surrounded by any nucleoprotein
coat.
•
Lichens-Lichens are symbotic association betweenalgae and fungi. The fungal
component is known as mycobiont and the
algal component is known as phycobiont.
•
Phycobiont synthesise organic food by
IMPORTANT QUESTIONS
1.
photosynthesis,fix nitrogen etc.
Dinoflagellates are mostly
(a) Marine saprophytic
•
Mycobiont protects the alga, absorb water and minerals for lichen.
(b) Fresh water and saprophytic
•
Prions : In modern medicine certain in-
(c) Marine and photosynthetic
fectious
neurological
diseases
were
(d) Terrestrial and photosynthetic
found to be transmitted by an agent consisting of abnormally folded protein.
2.
The agent was similar in size to viruses.
Fill in the blanks.
1) Rhizopus
:
most notable diseases caused by prions are
Yeast
——————
bovine
2) Hold fast
These agents were called prions. The
spongiform
encephalopathy
(BSE) commonly called mad cow disease
:
:
Phycomycetes
Anchorage
Heterocyst : ——————
in cattle.
3.
Find out the odd one:
Diatom, Gonyaulax, Yeast, Euglena,
Plasmodium
Plus 1 Biology
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Biological Classification
your parents, who will never let you down • 266 .
4.
5.
1) Vibrio : comma shaped
(a) Viral diseases
———— : Rod shaped
(b) bacterial diseases
2) Agaricus : Basidiomycetes
(c) Protozoan diseases
Penicillium : ————
(d) fungal diseases
Name the following :
10.
virus is
1. A protist which can live both as an
autograph and as heterotroph.
(a) Prion
2. Name a protist group which consists
(c) bacteria (d) mycoplasma
of saprophytes.
6.
8.
Which of the following phenomena
ble indicator of SO2 pollution in the en
proves that viruses are living?
vironment
(a) They carry on metabolic activity
(a) Lichens
(b) They carry anaerobic respiration
(c) Algae
12.
(b) Conifers
(d) Fungi
Pick up the wrong statement.
(d) They cause infection
a)
Cell wall is absent in Animalia.
Tobacco mosaic virus is
b)
Protista have photosynthetic and
(a) spherical
(b) rod shaped
(c) cuboidal
(d) oral
heterophic modes of nutrition.
Viruses are also known as
c)
Some fungi are edible
d)
Nuclear membrane is present in
Monera.
(a) nucleoprotein particles
9.
(b) viroids
11. Which of the following is the most suita
(c) They multiply in host cells
7.
An infectious agent that is smaller than
13.
Which one of the following statements is
(b) virion
wrong?
(c) Protozoan diseases
a) Golden algae are also called desmids.
(d) core
b) Eubacteria are also called False ba–
cteria
In plants, mosaic formation, leaf rolling
and curling, yellowing and vein clearing,
c) Phycomycetes are also called algal
are the symptoms of
fungi.
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Biological Classification
Hard work beats talent when talent doesn't work • 267 .
d) Cyanobacteria are also called called
20.
blue green algae.
14.
tensively in biochemical and genetic
work?
Citrus canker is a
(a) Viral disease
(b) Bacterial disease
(c) fungal disease (d) Protozoan disease
15.
The free living thalloid body of the slime
mould is known as
(a) Protonema
Which of the following fungi is used ex-
21.
(a)
(b) plasmodium
(a) Neurospora
(b) Mucor
(c) Rhizopus
(d) Aspergillus
Match them Properly
Chryso-
1.
Parame-
phytes
cium
(b)
Dinoflagel- 2.
Saprophyt-
(c)
Euglenoids 3.
Euglena
(d)
Slime
Gonyaulax
(c) fruiting body (d) Mycelium
16.
Trypanosoma causes
(a) sleeping sickness
(c) malaria
(b) Cholera
(d) food poisoning
4.
moulds
(e)
Protozoans 5.
Diatoms
and golden
algae
17.
Among rust, smut and mushroom, all the
22.Match the column Properly
three
(a) are pathogens
(b) are saprobes
(a)
Coccus
1.
shaped
(c) bear ascocarps (d) bear basidiocarps
18.
Insectivorous plants are principally
Rod
(b)
Bacillus
2.
Spherical
(c)
Vibrio
3.
Spiral
(a) Autotrophs
(b) Partially heterotrophic
shaped
(c) Parasite
(d)
Spirillum
4.
shaped
(d) pathogenic
19.
Comma
All the given belong to Deuteromycetes,
except
(a) agaricus
(b) Cercospora
(c) Ticoderma
Plus 1 Biology
(d) pyricularia
23.
What is capsid? What is its function?
24.
What are Prions?
25.
What is called Alternation of Genera-
Winner’s Coaching Centre
Biological Classification
Value yourself to fight for happiness • 268 .
tions?
26.
Why
iv.
Deuteromycetes are called class
(a) (ii) and (iii)
imperfect fungi?
(b) (i) and (iv)
PREVIOUS YEARS QUESTIONS
27.
Algal component of lichen is phycobint.
(c) (i) and (iii)
Observe the figure given below. Name
the organism.
(d) (ii) and (iv)
31.
The name ‘Virus’ that means venom or
poisonous fluid was given by
32.
(a) Pasteur
(b) Ivanowsky
(c) Beijerinck
(d) Stanley
The class of fungi known as imperfect
fungi is———
(a) Ascomycetes
28.
(b) Phycomycetes
Observe the relationship between the
first two terms and fill in the blank.
(a) Mushroom
: Agaricus
(d) Basidimycetes
(b) Bread mould : ————
29.
(c) Deuteromycetes
33.
Fill in the blank:
ble to cyanobacteria.
In Anabaena specialized cells called —
a)
Important decomposers
b)
Form blooms in polluted water
c)
Presence of prominent nucleus
d)
Completely lack of a cell wall
—— help in nitrogen fixation.
30.
Read the following statements and select
the correct statements from the given
choices:
i.
Identify the statement which is applica
Methanogens are present in the guts of
Observe the relationship between the
first pair and fill up the blanks using ap
ruminant animals.
ii.
Mycoplasma has distinct cell wall.
iii.
Viroids are infectious naked DNA molecules.
34.
propriate terms.
(a)
Carolus Linnaeus—Two kingdom
classification
R.H. Whittaker - —————
Plus 1 Biology
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Biological Classification
Think like a proton, always positive • 269 .
35.
(b) Thermoacidophiles - Extreme heat
(a) What is symbiosis?
Halophiles - ————
(b) State the economic importance of
Lichens.
Diatoms, the chief producers in the
oceans, are useful to us even after their
40.
death. Evaluate the statement.
36.
Five kingdom arrangement of organisms
was given by R.H. Whittaker, State the
criteria followed by Whittaker for his
Fill up the second part by observing the
classification.
relationship of the first part.
41.
(a) Monera - Prokaryote
Slime moulds grow in damp places.
(a) Name the vegetative part of thallus.
Protista - ————
(b) Give an example of slime mould.
(b) Bacteria live in extreme salty areas -
ANSWERS
Halophiiles
Bacteria live in marshy areas - ——
1.
c) Marine and photosynthetic
2.
1) Ascomycetes
3.
Yeast
4.
1) Bacillus
2) Ascomycetes
Halophiles
5.
1) Euglena
2) Slime mould
Archaebacteria growing in hotsprings -
6.
c) They multiply in host cells.
7.
b) Rod shaped
8.
a) Nucleoprotein particles
9.
a) Viral diseases
plants- ———
10.
b) Viroids
Ramu decided to construct a biogas plant
11.
a) Lichens
in his home due to the recent hike in the
12.
d) Nuclear membrane is present in mon-
37. Observe the relationship between the
words of the first sentence and fill the
second one.
(a)
Archaebacteria growing in salty areas—
——
(b)
Association of fungus with algae - Lichens
Association of fungus with roots of
38.
cost of cooking gas. Name the group of
bacteria involved in this process.
39.
era.
13.
Lichens are symbiotic association of Al
gae and Fungi.
Plus 1 Biology
2) N2 fixation
b) Eubacteria are also called false bacteria.
14.
b) Bacterial disease
Winner’s Coaching Centre
Biological Classification
Today a reader, Tomorrow a leader • 270 .
15.
b) Plasmodium
16.
a) Sleeping sickness
17.
d) Bear basidiocarps
18.
b) Partially heterotrophic
19.
a) agaricus
20.
a) Neurospora
called capsomeres. The capsid protects
the nucleic acid.
The capsomeres are
arranged helical or polyhedral geometric
forms.
24.
They are abnormally folded proteins that
cause some infectious neurological disease. These are similar in size to viruses.
This causes bovine spongiform encepha-
lopathy [BSE] or mad cow disease in
21.
cattle. Its analogous variant causes Cr (a)
Chryso-
5.
phytes
Diatoms
Jacob (CJD) disease in humans.
and golden
25.
algae
(b)
Dinoflagel- 4.
The life cycle of plants has two distinct
phases – the diploid sporophytic and the
Gonyaulax
lates
haploid
haploid gametophytic phase.
(c)
Euglenoids 3.
Euglena
These phases alternate with each other.
(d)
Slime
Saprophyt-
The lengths of the haploid and diploid
moulds
ic protists
phases vary among different groups of
Protozoans 1.
Parame-
plants. This phenomenon is called Alter-
(e)
2.
cium
nation of Generation.
22.
26.
They are usually known as imperfect
fungi because only the asexual or vegeta-
(a)
Coccus
2.
Spherical
tive phase of them is known. A large
number of deuteromycetes are decom-
(b)
(c)
(d)
Bacillus
Vibrio
Spirillum
1.
4.
3.
Rod
posers, while some members are para-
shaped
sites.
Comma
27.
Euglena
shaped
28.
Rhizopus
Spiral
29.
Heterocyst
30.
(i) and (iv)
31.
Ivanowsky
32.
Deuteromycetes
shaped
23.
The protein coat on the virus is called
capsid. It is made up of small sub units
Plus 1 Biology
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Biological Classification
Today a reader, Tomorrow a leader • 271 .
33.
Form blooms in polluted water
34.
(a) five kingdom classification
(b) Extreme salt
35.
Diatomaceous earth used in polishing,
filtration of oils and syrups.
36.
(a) Eukaryote
(b) Methanogens
37.
(a) Thermoacidophiles
(b) Mycorrhiza
38.
Methanogens
39.
(a) Close and prolonged interaction be
tween organisms of different species.
(b) Litmus is obtained from a lichen, Ro
cella montaignei.
Lichen is used in the preparation of usnic
acid.
40
(1) Complexity of structure of cell
(2) Complexity of the body of organisa
tion
(3) Mode of nutrition.
41.
(a) Plasmodium
(b) Physarum
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Biological Classification
Nothing can stop you now • 272 .
CHAPTER-3
PLANT KINGDOM
affected by environment.
Plant kingdom
includes
all
the
pho-
tosynthetic producers of biosphere,
Fungi and members of Monera and Protista
having cell walls have now been excluded from
plantae.
2. Natural system of classification
In this system of classification not only the external features, but also internal features like
ultrastructure, anatomy,
1. Artificial system of classification
•
based on one or a few superficial characters.
•
•
and Joseph Dalton Hooker.
The artificial system of classification is
3. Phylogenetic system of classification
This system of classification uses only su-
In this system of classification, organisms are
perficial morphogical characters such as
classified on the
habit, colour, numberand shape of leaves
quence and genetic relationships among the
etc.
organisms.
This classification is based mainly on the
vegetative characters or on the androccium structure (system given by Linnaeus).
basis of evolutionary se-
Eg: Engler and Prantl's classification.
Numerical Taxonomy
•
Drawbacks of artificial system of classifica-
Taxonomy based on statistical methods is
called numerical taxonomy.
tion
•
i)
This method utilizes calculating ma-
This system separated closely related
chines and computers for the evaluation
species.
of similarities and differences between
the different species of organisms.
ii) Artificial system gave equal weightage to
vegetative and sexual characteristics.
This is not acceptable since we know that
vegetative characters are more easily
Plus 1 Biology
Cytotaxonomy
•
Taxonomy of organisms by the use of
their cytological characters is called cyto
cytotaxonomy.
Winner’s Coaching Centre
Plant Kingdom
There is no substitute for hard work • 273 .
•
The cytological features like chromo-
(Chlamydomonas) or non
flagellated
some number,structure and behaviour
(Chlorella), colonial form (Volvox) or
of chromosomes are used for classifica-
multicellular filamentous (Ulothrix and
tion.
Spirogyra). Some are flattened and leaf
like (Laminaria).
Chemotaxonomy.
•
•
5.
It uses the chemical constituents of the
forms. The attached forms fix the plant
plants in classification.
body with the help of anchoring structure
The sequencing of DNA and chemical
called holdfast.
nature of proteins are commonly used to
6.
study similarities of species.
•
They reproduce by vegetative, asexual
and sexual methods.
Calcium oxalate crystals (raphides) are
7.
commonly found in 35 families of
plants.
Vegetatvie reproduction takes place by
fragmentation.Eg: Sargassum.
8.
Asexual reproduction is by the production of different types of spores like zoo-
ALGAE
spores.Zoospores are flagellated(motile)
Algae (singular-alga) are chlorophyll bearing
simple thalloid,
the study of
and on germination produces new plants.
9.
Sexual reproduction takesplace by the
fusion of two
algae is called phycology.
size (eg:
Chlamydomonas) or non flagellated (non
Salient features of algae
1.
Algae may be free-floating or attached
- motile) but similar in size (eg: Spirogyra). Such reproductions called isoga-
Algae are chlorophyll bearing, auto-
mous.
trophic organisms.
Fusion of
2.
size
habitat.
is
two
gametes
dissimilar
in
termed anisogamous. (Eg.. Some
species of Chlamydomonas)
3.
4.
They occur in moist stones, soils and
wood. Some of them also occur in asso-
Fusion between one large, non motile female
ciation with fungi (lichen) and animals
gamete and a smaller motile male gamete is
(eg: on sloth bear)
called oogamous (eg:Volvox, Fucus),
The thallus is unicellular flagellated
Economic importance of algae
Plus 1 Biology
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Plant Kingdom
Whatever you are, be a good one • 274 .
1.
At least half of the total CO2 fixation on
earth is carried out by algae through photosynthesis. The increases the level of
dissolved oxygen (DO) in the immediate
phyceae.
1. Chlorophyceae (green algae)
I.
Algae are primary producers of energy
II.
the food cycles of all aquatic animals.
They
bear
pigments-
III.
The chloroplasts may be discoid, plate
Many species of Laminaria, Porphyra
like, reticulate,cup-shaped spiral or rib-
and Sargassum are used as food.
bon shaped in different species
Certain
large
marine
amounts
algae
produce
IV.
(large brown algae)
containting
protein besides
starch.
V.
Eg: (i) Algin from brown algae like kelps
They have storage bodies called pyrenoids
of hydrocolloids
(water holding substances).
Cell wall made up of cellulose.
VI. Vegetative reproduction by fragmentation or by theformation of different types
(ii) Carrageen is obtained from red algae.
of spores.
VII. Asexual
3.
dominant
chlorophyll a and b in chloroplasts.
rich compounds which form the basis of
3.
unicellu-
lar, colonial or filamentous.
environment,
2.
The plant body may be
reproduction
is
by
Agar is a gel like substance obtained
flagellated zoospores produced in zoo-
from
sporangia.
red
algae
like Gelidium and
Gracilaria
VIII. Sexual reproduction occurs by the formation of sex cellsand it may be isoga-
Agar is used as a culture medium for bac-
mous,anisogamous or oogamous. Ex-
teria, fungi and other microbes. Agar is
ample:
also used in the preparation of icecreams
Ulothrix, Spirogyra and Chara,
Chlamydomonas,
Volvox,
and jellies.
Chlorella and Spirullina are unicellular
algae rich in proteins, used as food supplements even by space travellers.
Algae are divided into three main classes.
Chlorophyceae, Phaeophyceae and RhodoPlus 1 Biology
Winner’s Coaching Centre
Plant Kingdom
Education is the key to success • 275 .
phylls. The colour of the thallus vary
from olive green to various shades of
brown depending upon the amount of
xanthophylls pigment fucoxanthin.
IV.
Food is stored as complex carbohydrates,
which may be in the form of laminarin
or mannitol.
V.
on outside by a gelatinous coating of algin.
VI.
The protoplast contains a centrally located vacuole and nucleus.
VII. The plant body is usually attached to the
substratum by a holdfast. The stalk of
the algae is called stipe and the leaf like
photosynthetic organ is called frond.
VIII. Vegetative reproduction takes place by
fragmentation.
pear
shaped and have two unequal flagella.
IX.
Sexual reproduction is isogamous, anisogamous or oogamous. Fusion of gam-
2.
Phaeophyceae (Brown algae)
etes may take place in water or in the oogonium (in oogamous species). The
I.
They are found in marine habitat.
II.
They are multicelluar. Some are simple
gamete are pyriform (pear-shaped) and
bear two laterally placed flagella.
branched filamentous forms (eg: Ecto-
Eg: Ectocarpus, Dictyota, Laminaria,
carpus).Largest sea brown algae are
Sargassum, Fucus.
called sea weeds or sea kelps having a
length of100 metres.
III.
Photosynthetic pigments include chloro-
4. Rhodophyceae (Red algae)
phyll a, c, carotenoids and xanthoPlus 1 Biology
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Plant Kingdom
There is no substitute for hard work • 276 .
I.
Majority of red algae are marine.
II.
They are red due to the presence of red
3)
um. They produce biflagellate antherozoids.
pigment, r- phycoerythrin.
4)
They occur in warmer areas. They are
I.
The female sex organ is called archegonium. It is flask shaped and produces sin-
found in well lighted areas close to the
gle egg.
surface of water and also at great depths
in oceans, where little light penetrates.
The male sex organ is called antheridi-
5)
The antherozoids are released into water
where they come in contact with the ar-
II.
The thallus is multicellular.
III.
The food is stored as floriedean starch.
IV.
Vegetative reproduction is by frag-
chegonium. Thus water is essential for
fertilisation.
6)
duce the zygote.
mentation. Asexual reproduction by
non-motile spores. Sexual reproduc-
Antherozoid fuses with the egg to pro-
7)
The zygote develops into a multicellular
tion by non motile gametes. Sexual re-
body called sporophyte. The sporophyte
production is oogamous.
is not free living but attached to the photo-
Example:
Gracilaria,
synthetic gametophyte and derives nour-
Polysiphonia,
ishment from it.
Porphyra and Gelidium.
BRYOPHYTES
The plants can live in soil but are dependent
8)
The sporophyte undergoes reduction
division (meiosis) to produce haploid
on water forsexual reproduction, bryophytes
spores. The spores germinate toproduce
are known as "amphibians of plant king-
gametophyte
dom" They occur in damp humid and shaded
localities.
1.
Characteristics of bryophytes
1)
Economic Importance of Bryophytes
birds and other animals.
The plant body is thallus like and prostrate or erect. It is attached to the sub-
2.
zoids. They lack true roots, stem or
Mosses bind soil and hence prevent soil
erosion.
stratum by unicellular or multicellular rhi-
2)
Some mosses provide food for mammals,
3.
The Moss Sphagnum is used by garden-
leaves, but they may possess root like,
ers to keep cut plant parts moist during
leaf like or stem like structures.
transportation. Sphangnum provide peat
that have long been used as fuel.
The plant body is a gametophyte ie, can
produce gametes.
Plus 1 Biology
4.
Mosses along with lichens are the first
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Always have an attitude of gratitude • 277 .
organisms to colonise rocks and hence
are of great ecological importance.
They decompose rocks making
the
with the egg nucleus.
•
sisting of foot, seta, capsule arises from
substrate suitable for the growth of high-
the fertilised egg of the archegonium.
er plants.
Bryophytes are divided into liverworts and
•
•
The plant body is a green, flat and dorsiven-
•
of unicellular hair like structures called rhizoids.
of
liverworts:
-
Riccia,
(ii) Mosses
i) They are found growing in moist places.
Asexual reproduction takes place by frage-
ii) The plant body is a gametophyte. The
mentation of thalli,or by the formation of specialised structures called gemmae (gemma).
gametophyte occurs in two forms.
(i)
creeping, green, branched and filamen
buds, which develop in small receptacles in
tous stage.
the thallus called gemma cups.
The gemmae are detached from the parent
body and germinate to form new individuals.
Protonema stage. It is formed from the
germination of spore. Photonema is a
Gemmae are green, multicellular, asexual
(ii)
Leafy stage. It develops from secondary
protonema as a lateral bud. It consists of slender erect axis bearing spirally arranged
The male reproductive branches called
leaves. Basal portion bears numerous multi-
antheridiophore.Female branch is called
cellular branched rhizoids.
archegoniophores.
Reproduction
Antheridia produce flagellated sperms
(antherozoid).
Vegetative reproduction in mosses is by
Archegonia produce female gametes (egg
cell)
•
Examples
Marchantia
tral thallus. It is attached to the soil by means
•
The spores germinate to form free living
gametophytes.
(i) Liverworts
•
The spores are formed in the capsule after
meiosis which are dispersed by wind.
mosses.
•
After fertilisation a tiny sporophyte con-
fragmentation and budding in the secondary
protonema
Antherozoids swim in water and fuses
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Sexual reproduction:
the
fertile leaves called sporophylls.
In some cases sporophylls may form dis1.
Antheridium is an orange colored club-
tinct compact structures called strobili or
shaped structure. It produces the flagel-
cones. Eg: Selagenella, Equisetum.
lated sperms (antherozoids) Female
2.
branches produce flask shaped female
iv) The sporangia produce spores. The spores
reproductive organs called archegonia.
are produced by meiosis of spore mother
Archegonium produces the egg.
cells. The spores are uninucleate and hap-
v)
reach the egg cell.
3.
loid.
The antherozoids swim in water to
shaped photosynthetic structure called
After fertilisation the zygote develops
prothallus. The prothallus is the haploid
into a sporophyte. The sporophyte is
gametophyte.
differentiated into foot, seta and capsule.
4.
The spores are formed in the capsule af-
vi) The gametophyte
organ
ter meiosis.The spores are dispersed by
bears
male
sex
called antheridia and female sex
organ called archegonia.
wind. Spores germinate
pro-
The spores germinate to form a thin heart
vii) Antheridia produce antherozoids. Archegonia produce oosphere (egg cell).
tonema.
Example:-Funaria,
Polytrichum
and
viii) Water is essential for fertilisation. Fu-
Sphagnum.
sion of male gamete with the egg present
in the archegonium results in the formation of zygote.
PTERIDOPHYTES
The
pteridophytes
include
horse
tails
ix) Zygote produces multicellular well differentiated sporophyte which is the domi-
(Equisetum) and ferns.
nant phase of pteridophytes.
General characteristics
i)
x)
These are seedless vascular plants.
ii) Plant body is a sporophyte which is
differentiated into true roots, stem and
jority of pteridophytes all the spores are
of similar types. Such plants are called
homosporous.
Heterosporous Pteridophytes
leaves.
iii) The sporangia arise on the lower side of
Plus 1 Biology
The sporophyte produces spores. In ma-
Genera like Selagenella and Salvinia which
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Be giving, enjoy sharing • 279 .
produce
two kinds of spores-megaspores
v)
In Cycas the leaves are persistant for a
(large) and microspores (small) are known as
few years. The leaves of gymnosperms
heterosporous.
are
to
withstand extreme
temperature, humidity and wind. The
The megaspore germinate to form female ga-
needle like leaves of conifers reduce the
metophyte. The microspore germinate to form
surface area. The thick cuticle and sunk-
male gametophyte.
The pteridophytes
adapted
en stomata also help to reduce water
are
classified into
following four classes
loss.
vi)
They are vascular plants with xylem
i)
Psilopsida (Eg. Psilotum)
and phloem tissue. Xylem lacks vessels
ii)
Lycopsida (Eg. Selagenella, Lycopodi
and phloem lacks companion cells.
um)
vii) They are seed
bearing
flowerless
plants.
i)
Sphenopsida (Eg.Equisetum)
ii)
Pteropsida (Eg.Pteris,Adiantum)
GYMNOSPERMS
viii) The plant body is a diploid sporophyte
(2n).
Reproduction
The gymnosperms are seed bearing vascular
plants without flower. They are naked seed-
Gymnosperms are heterosporous ie.. bear two
ed plants.
different types of spores such as microspores
(male) and megaspores (female). The micro-
General Characters
spores develop in microsporangia. The mega-
i)
spores develop in
Gymnosperms are naked seeded plants.
like structures
ii)
iii)
The plant body is differentiated into
called sporophylls. The sporophylls are
roots, stem and leaves.
two types megasporophylls and microsporo-
The root is a taproot system and is well
phylls
developed. Roots in some genera have
The reproductive structures are called lax
fungal association in the form of
or cones or strobili.
small specialised roots called
coralloid roots are associated N2, fixing
The stems are branched or un branched.
Plus 1 Biology
The male cone consists of microsporophylls
and female cone consists of megasporophylls
Microsporophylls
cyanobacteria.
iv)
of
(pollen
bear microsporangia
sac)which contains pollen grains
(microspores).
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Megasporophylls bear megasporangia
7.
Which one is responsible for the for-
(ovules). In the megasporangium the mega-
mation of peat?
spore mother cell is differentiated from one of
a)
Riccia
b)
Sphagnum
bryo and the ovule develops into seeds.
c)
Marchantia
IMPORTANT QUESTIONS
d)
Funaria
the cells of the nucellus.
After fertilization zygote develops into em-
8.
1.
A colonial algae is ———
2.
Agar - agar is commercially obtained
from ——
3.
4.
Rhodophyceae is called red algae be10.
b) Funaria
c) Marchantia d) Fucus
Isogamous
condition
with
non-
flagellated gametes is found in
Antheridium : Male sex organ
—————-: Female sex organ
Which of the following is a liverwort?
a) Sphagnum
5.
Rhodophyceae :
9.
cause of the pigment——
Chlorophyceae : Green algae
A plant that has seeds but no flowers and
fruits
11.
The cell wall of spirogyra contains ——-
12.
——————: Naked seeded plants
13. Pinus : Mycorrhizal roots
Cycas : ——-
a) Chlamydomonas
14. Analyse the table and fill in the blanks.
b) Spirogyra
Algal class
Pigment
Stored food
d) Fucus
1. Phaeophycean
Fucoxanthin
(1)
In gymnosperms, the development of
2. Chlorophyceae
(2)
Starch
Rhodophyceae
(3)
(4)
c) Volvox
6.
pollen grains occurs in
a) Strobili
b) Microsporangia
c) Megasporangia
d) Macrosporangia
Plus 1 Biology
PREVIOUS YEARS QUESTIONS
15. The given figure shows a plant belonging
to liverworts. Identify the plant. Name
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Dedication is expensive than talent • 281 .
the asexual buds seen on it and write their
features.
Chlorophyll
a, b
Phaeophyceae
Chlorophyall Laminarian
a, c and (b) and Mannitol
(c)
20.
(a)
Chlorophyceae
Chlorophyll
a, d and phycoerythrin
(d)
Amphibians of plant kingdom is used do
denote a specific group in plant kingdom
Name the plant group and list any three
vegetative or reproductive characters of
that plant group.
21.
on aquatic ecosystems, man is benefited
16. Match Column A and Column B
A
1) Prothallus
2) Protonema
Even though algae are primary producers
by algae in a variety of ways. Write any
four points in favour of this statement.
B
i) Asexual buds in liverworts
22.
Write the name of the stored food of the
algal class in the table given below:
ii) Sporophyte of Angiosperms
Class
Stored food
3) Antheridium iii) Thalloid gametophyte
of pteridophytes
4) Gemmae
iv) Male sex organ in bryotes
v) Gameophytic stage of
1) Phaeophyceae
2) Rhodophyceae
17. Algae are useful to man in a variety of
ways. Suggest any four uses off algae.
18.
Write any two distinguishing features of
the algal class Rhodophyceae.
19.
23. Distinguish between protonema and pro
thallus
24. Match the columns A and B:
Complete the given table of algal divi
sions and their main characteristics by
filling (a), (b), (c) and (d).
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A
B
(i) Prothallus
a)
Identify two heterosporous genera.
b)
“Heterosporty is a precursor to
seed habit”. Point out any one
(a) Mosses
common character found in heter
(ii) Sporophyte
(b) Plant body of
algae
(iii) Coralloid
roots
(c) Gametophyte
of pteridophytes
(iv) Protonema
(d) Sporangia
bearing leaves
ospory and seed habit.
ANSWERS
1.
Volvox
2.
Gracilaria and Gelidium
3.
Phycoerythrin
4.
c) Marchantia
genera like selaginella and salvinia show
5.
b) Spirogyra
a unique feature in spore formation.
6.
b) Microsporangia
a.
7.
b) Sphagnum
8.
Rhodophyceae : Red algae
9.
Archegonium
10.
Gymnosperms
11.
Cellulose
12.
Gymnosperms
(e) Nitrogen fixa25. Unlike a majority of the pteridophytes,
What is this feature?
b.Briefly
comment
on
its
signifi
cance.
26. Match the Column A with B
A
B
a)
Floridena starch
Gymno-
b)
Double fertiliza-
Red algae
13.
Coralloid roots
c)
Coralloid roots
Fern
14.
1) Mannitol and Laminarin
d)
Prothallus
Angisperm
2) Chlorophyll a
3) Phycoerythrin
27. Give reasons for the following:
4) Floridean starch
a) Bryophytes are called amphibians of
15.
plant kingdom.
28.
Marchantia, Gemma cup
Most pteridophytes are homosporous but
Features : Gemmae are green multicellu
there are exceptions.
lar, asexual buds which develop into
small receptacles. Gemmae become de
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Practice makes progress • 283 .
tached from the parent body and germi
nate to form new individuals.
16.
A
17.
Starch (a)
Phaeophyceae
Chlorophyall Laminarian
a, c and (b) and Mannitol
fucoxanthin
v) Gametophytic stage
of mosses
Rhodophyceae (c)
Chlorophyll
a, d and phycoerythrin
Floridean
starch (d)
20. Bryophytes
3) Antheridi- iv) Male sex organ in
Vegetative characters
4) Gemmae
1.
Thallus is prostrate or erect.
2.
They lack true roots, stem or
i) Asexual buds in liverworts
1. During photosynthesis algae fix CO2
and liberate O2
2.
3.
Certain marine algae are used as
Presence of unicellular or multicell
lular roots.
Reproductive characters
Marine brown and red algae pro
duce hydrocolloids. E.g., Algin
4.
leaves.
3.
food
They are primary producers in an
The main plant body of the Bryo
2.
The male sex organ is multicellular
antheridium.
Flagella are not present in gamete and
spores.
3.
The female sex organ called Ar
chegonium
Red pigment phycoerythrin is present.
19.
1.
phyte is haploid
aquatic ecosystem.
18.
Chlorophyll
a, b
B
1) Prothallus iii) Thalloid gametophyte of pteridophytes
2) Protonema
Chlorophyceae
21. 1.
Chlorella and Spirulina are rich in
protein.
2.
Agar—agar is obtained from
Gracilaria and Geledium
3.
Used for the preparation of ice—
creams and jellies.
4.
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Used for the growth of microbes.
Plant Kingdom
Nothing can stop you now • 284 .
22 . 1) Laminarian, Mannitol
23.
A
B
2) Floridean starch
a)
Floridena starch
Red algae
Protonema: It is a creeping, green, fila-
b)
Double fertiliza-
Angiosperm
directly from a spore of mosses.
c)
Coralloid roots
Gymno-
Prothallus: Heart shaped, photosynthet
d)
Prothallus
Fern
mentous, branched structure develops
ic gametophyte of pteridophytes.
27. They depend on water for sexual reproduc-
24.
tion.
A
B
(i) Prothallus
28. a)
(c) Gametophyte
of pteridophytea
(ii) Sporophyte
(d) Sporangia
bearing leaves
(iii) Coralloid
roots
(e) Nitrogen fixation
(iv) Protonema
(a) Mosses
25. a)
Selaginella and salvinia
b)
Female gametophyte is retained on
the parent sporophyte.
Heterospory
b)
(1)
The mega spores and micro
spores germinate and then give rise to
male and female gametophytes.
c)
(2) The development of zygote into
young embryo occurs within female
gametophyte.
26.
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CHAPTER - 4
ANIMAL KINGDOM
BASIS OF CLASSIFICATION
The individuals belonging to the animal kingdom differ in their structure and form.
equal halves through any - plane, it is called
asymmetry.
Eg: some sponges.
2.
But some fundamental features are common to
various individuals in relation to the
Radial symmetry
If an animal which can be cut into two equal
halves through any of the radial planes, it is-
1. Arrangement of cells
called radial symmetry
2. Level of body organization
3. Body symmetry
4. Nature of coelom.
5. Patterns of digestive, circulatory or reproductive systems. These fundamental fea-
tures are used as the basis of animal classification.
1.
Levels of organisation
1.
Cellular level of organisation
(aoomeler)
2.
Tissue level of organization
3.
Organ level of organization
Eg: Coelenterates, ctenophores and echino-
4.
Organ system level of organization.
derms
.
3.
Bilateral symmetry
II. Symmetry
If an animal which can be cut into two equal
The arrangement of body parts on the sides of
halves through a single plane along the longi-
the main median axis of a body is called Sym-
tudinal axis, it is called bilateral symmetry.
metry. It is of three types - asymmetry, radial
symmetry and bilateral symmetry .
1.
Asymmetry
If an animal which cannot be cut into two
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IV. Coelom (body cavity)
Eg: Annelids, man etc.
III. Diploblastic and triploblastic organisation
(i)
Diploblastic animals:
•
the body wall and the digestive tract of
animals is called the coelom.
Animals which
are developed from the two—layered
(germ layers) embryo, are called diploblastic animals.
•
The coelom is lined by the mesoderm
On the basis of the nature of coelom, animals
are divided into 3 groups.
The outer layer of the embryo is called
ecoderm, the inner layer is called endo
1.
Animals having no coe-
helminthes (flatworms).
lar layer is seen in between the ectoderm
and endoderm. It is called Mesoglea,
Acoelomates:
lom are called acoelomates. Eg: Platy-
derm . An undifferentiated non— cellu
2.
Pseudocoelomate: In some animals, the
body cavity is not lined by mesoderm,
Eg: Coelenterates and Sponges.
(ii)
The fluid—filled body cavity in between
instead, the mesoderm is present as scat
Triploblastic animals: Animals which
tered pouches in between the ectoderm
are developed from the three layered em-
and endoderm. Such a body cavity is
bryo, are called triploblastic animals,
called pseudocoelom.
Eg: Platyhelminthes to Chordates.
3.
Coelomates: Animals having true coe-
The 3 germ layers of the embryo are the
lom are called coelomates or eucoelo-
ecoderm, mesoderm, and endoderm.
mates. Eg: annelids, molluscs, arthropods,
echinoderms,
hemichordates,
and chordates
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Chordates: Animals with notochord eg: fishes, birds, mammals, etc.
Non - chordates: Animals without notochord
eg: Porifera to echnioderms.
CLASSIFICATION OF ANIMALS
Based on common fundamental features, the
kingdom Animalia is broadly classified into
11 phyla—Porifera, Coelenterata, Ctenophora, Platyhelminthes, Aschelminthes,
Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, and Chordata.
1. PHYLUM PORIFERA (Sponges)
(pore—bearing animal)
I.
V.
Segmaentation
They are asymmetrical, multicellular,
diploblastic with cellular level of organisation.
In some animals, the body is externally
and internally divided into segments with a
serial reptition of at least some organs. For
example, in earthworm the body shows this
II.
They are generally marine.
III.
They are pore—bearing animals and
their body is perforated by numerous
pattern called metameric segmentation and
openings or pores called ostia.
the phenomenon is known as metamer
IV.
ism.
They have a Water transport system
(water canal system).
VI. Notochord
In some animals, a mesodermally derived
V.
Water enters through ostia into a cen-
tral cavity called spongocoel.
rod—like structure is called notochord.
Water
from spongocoel goes out through os-
The notochord is a stiff and flexible rod of tis-
culum.
sue running along the dorsal side below the
transport is helpful in food gathering,
nerve cord and above the alimentary canal .
respiratory exchange and removal of
waste.
Based on the presence or absence of notochord, animals are classified into 2 groups Chordates and non - chordates.
Plus 1 Biology
This pathway of water
VI.
Choanocytes or collar cells line the spon
gocoel and the canals.
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VII. Digestion is intracellular.
2.
(Phylum Cnidaria)
VIII. Sponges have an endoskeleton formed
1.
of spicules and Spongin fibres.
IX.
Asexual reproduction takes place by
rical animals.
2.
Sponges are hermaphrodite (sexes are
3.
In coelenterates, certain ectodermal cells
are modified into stinging cells or cnido-
not separate).Eggs and sperms are pro
blasts or cnidocytes, hence the name
duced by the same individual.
Cnidaria
XII. Fertilisation is internal and the devel
opment of larva is indirect.
4.
Each cnidoblast possesses a stinging capsule called nematocyst containing poi-
Examples: Spongilla (fresh water
spong
They show tissue level organisation and
are diploblastic.
fragmentation and budding.
XI.
They are aquatic (mostly marine), sessile or free swimming radially symmet-
Sponges reproduce asexually and sex
ually
X.
PHYLUM COELENTERATA
sonous fluid. The cnidoblasts are defen-
es), Sycon (Scypha), Eu-
sive cells used to kill or paralyse other
spongia (bathsponge ).
prey and enemies. The cnidoblasts are
mainly found on the tentacles.
5.
They have a central internal cavity called
gastro vascular cavity coelenteron.
It
opens out by a single opening called
mouth on hypostome. Anus is absent.
6.
The coelenterates are holozic and carnivorous in nutrition. Digestion is intracellular and extracellular.
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7.
Coelenterates have 2 types of basic body
1.
jellies.
forms polyp and medusa.
Polyp
They are known as sea walnuts or comb
:- is the sessile tubular (cylindrical
2.
They are exclusively marine, radially
attached form, with upwardly directed mouth
symmetrical, diploblastic organism and
tenacles. It Presents theasexual stage. .
acoelomates
Eg: Hydra and Adamsia.
3.
They show tissue level of organisation.
Medusa: - is the umbrella—like, free—
4.
Animal body bears 8 external rows of
swimming form, with downwardly directed
cilia. Cilia in each row together to form
mouth and tentacles. It represents the sexual
Comb plates which help in locomotion.
stage. Medusa can be regarded as an upside—
5.
down polyp with reduced stalk and capable of
Digestion is both extracellular and intracellular.
swimming way.
6.
Eg: Aurelia (opeilo, jelly fish).
organism to emit light ) is well marked.
Coelenterates exhibit alternation of generation (metagenesis) in their life cycle.
Bioluminescence (the property of living
7.
They reproduce Sexually only.
8.
They are hermaphrodites
(male and
female sex organs are seen in one animal.)
9.
Fertilisation is external
with indirect
development.
10.
The zygote develops into a larvae which
grows into an adult.
Examples: Pleurobrachia (sea gooseberry),and Ctenoplana.
PHYLUM CTENOPHORA
(Sea walnuts or comb jellies)
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4.
PHYLUM PLATYHELMINTHES
(flat worms)
4. PHYLUM - ASCHELMINTHES
1.
(round worms)
They have dorso - ventrally flattened
body, hence are called flatworms.
2.
These are mostly endoparasites found in
animals including human beings
3.
They are bilaterally symmetrical triporgan level of organisation.
Hooks and suckers are present in the
3.
4.
Some of them absorb nutrients from
face.
Shows bilateral
symmetry,
triplo-
They
show
developed
muscular
plete .
5.
They are dioecious, ie. Male and female
s are different ;
Specialised cells called flame cells help
in osmoregulation and excretion.
7.
Sexes are not separate.
8.
Fertilisation is internal and development is through many larval stages.
9.
parasitic in plants
pharaynx and alimentary canal is com-
the host directly through their body sur-
6.
They are freeliving, aquatic, terrestrial or
blastic pseudocoelomate animal.
parasitic forms.
5.
They show organ - system level of body
organisation.
2.
loblastic and acoelomate animals with
4.
1.
Some members like Planaria possess
high regeneration capacity.
6.
The male is smaller than the female.
7.
Fertilisation is internal.
8.
Excretion is done through excretory
pore.
E.g. : Ascaris (round worm), Wauchere
ria
(filariaworm)
and
Ancylostoma
(hookworm).
Example: Taenia (Tapeworm), Fasciola
(Liver fluke).
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leech).
6.
PHYLUM ANNELIDA
(Segmented worms)
1.
Annelids
are
terrestrial
(eg.
Earth
worms) or marine (eg: Neries) or fresh
water (eg: Nais) or parasitic (eg: leeches).
2.
They possess an organ - system level of
body organisation.
3.
Annelids are bilaterally symmetrical ,
triploblastic and coelomate.
4.
They are metamerically segmented.
Body is externally (body surface) divided
5.
into segments called metameres. Hence,
7.
the phylum name annelida.
Arthropods are animals with jointed legs and
appendages
They possess longitudinal and circular
PHYLUM ARTHROPODA
1.
This is the largest phylum of Animalia.
2.
They have organ –system level of organization.
3.
They are bilaterally symmetrical, triploblastic, segmented and coelomate
animals.
which help in locomotion.
4.
The body is covered by Chitinous exoskeleton.
7.
Circulatory system is of closed type
5.
8.
Nephridia (singular nephridium ) help
The body consists of head, thorax and
abdomen
6.
They have jointed appendages.
7.
Respiratory organs are gills, book gills,
book or tracheal system.
8.
Circulatory system is of open type.
9.
Sensory organs like antennae, eyes
muscles which help in locomotion..
6.
Aquatic annelids like Nereis possesses
lateral appendages, parapodia which
help in swimming. Others (e.g : - carthworm) have setae on the undersurface
in osmorgulation and Excretion.
9.
Nereis, an aquatic form, is dioecius, but
earthworms and leeches are monoecious.
10.
Reproduction is sexual.
Examples:
Nereis.
Pheretima
(Earthworm) and Hirudinaria (Blood sucking
Plus 1 Biology
(compound and simple), Statocysts or
balance organs are present.
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10.
hump.
Excretion takes place through malpighian tubules.
6.
The head region has sensory tentacles.
7.
The mouth contains a file - like rasping
11.
They are mostly dioecious.
12.
Fertilisation is usually internal. They are
organ called radula (With transverse
mostly oviparous.
rows of teeth) for feeding.
13.
Development may be direct or indirect.
Examples Arthropoda; (a) Locust.
8.
and spongy layer of skin called mantle.
(b)
Butterfuly (c) Scorpion (d) Prawn.
The visceral hump is covered by a soft
9.
Gills are the respiratory organs.
10.
The anterior head region has Sensory
tentacles,
11.
They are dioecious and oviparous.
Examples: Pila (apple snail, Pinctada
(Pearl oyster), Sepia (cuttlefish), Octo
pus (Devilfish), Dentalium (tusk shell),
Chaetopleura (chiton), etc.
8.
PHYLUM MOLLUSCA
1.
Phylum Mollusca forms the Second
largest phylum of the animal kingdom.
2.
They are terrestrial or aquatic (marine
or fresh water).
3.
They are bilateral, symmetrical, triploblastic and coelomate animals.
4.
Body is covered by a Calcareous shell.
5.
Body is unsegmented by consists of distinct head, muscular foot and visceral
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9.
PHYLUM—ECHINODERMATA
(spiny bodied animals)
1.
All are marine
2.
They have endoskeleton of calcareous
ossicles and hence the name Echinodermata (spiny bodied).
3.
Triploblastic, coelomate, organ system
level of organisation.
4.
The adult echinoderms are radially symmetrical
but
larvae are bilaterally
symmetrical.
5.
Digestive system is complete with mouth
on the lower (ventral ) side and anus on
the upper (dorsal ) side.
10.
Presence of Water Vascular system
Hemichordata was earlier considered as a
which helps in locomotion, capture and
sub - phylum under phylum Chordata. But
transport of food and respiration.
now it is placed as a separate phylum under
7.
Excretory system is absent.
non - chordata.
8.
Sexes are separate.
1.
9.
Reproduction is sexual.
10.
Fertilisation is usually external.
11.
Development is indirect with free -
6.
PHYLUM—HEMICHORDATA
This phylum consists of a small guoup of
worm - like marine animals with organ
system level of organisation.
2.
swimming larva
loblastic and coelomate.
3.
trunk.
(sea urchin), Antedon (Sea lily), Cucumaria
Plus 1 Biology
The body is cylindrical, composed of an
anterior Proboscis, a collar and a long
Examples: Asterias (star fish). Echinus
(sea cucumber): and Ophiura (Brittle star).
They are bilaterally symmetrical, trip-
4.
Circulatory system is of open type.
5.
Respiration takes place through gills.
6.
Excretory organ is Proboscis gland.
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7.
Sexes are separate.
8.
Fertilisation is external.
9.
Development is indirect.
Notochord
It is the solid and flexible unjointed rode.
It is found on the dorsal side between the
alimentary canal and nerve cord.
Examples: Balanoglossus
and Sac
Dorsal hollow nerve cord
cogloussus.
In all chordates the nerve cord is single,
dorsal and hollow. It is placed above the
notochord.
Gill slits
All chordates possess paired haryngeal
gill slits.
They are lateral openings of
the pharynx which help in respiration.
11.
PHYLUM CHORDATA
1.
These are bilaterally symmetrical, triploblastic, coelomate
Classification of Chordata
with Orgna—
system level of organisation.
2.
They possess a post anal tail
They possess a notochord,
on the basis of the fate of the notochord . They
are (i) urochordata, (ii) cephalochordate,
and a
closed circulatory system.
3.
Phylum Chordata is divided into 3 sub—phyla
and (iii) Vertebrata.
i.
a dorsal
commonly called Protochordates (lower
hollow nerve cord and paired pharyngeal slits.
Plus 1 Biology
Urochordates and cephalochordates are
chordates).
ii.
Protochordates are exclusively marine.
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You may learn slowly but don't go back • 295 .
Sub - phylum Urochordata (tunicate)
sent for locomotion. They are fins or
limbs.
i.
They are marine protochordates.
ii.
Notochord extends from the anterior
v.
with 2, 3 or 4 chambers.
(head) to the posterior end (tail region) of
the body, and is persistent Throughout
Presence of a ventral muscular heart
vi.
life.
Kidneys for excretion and osmoregula
tion.
Example: It is represented by a single
genus, Branchiostoma (Amphioxus or
lancelet).
Classification of Vertebrates
Vertebrates are divided into two divisions.
(i) Agnatha (lacks jaw)
(ii) Gnathostomata (bears jaw)
I.
Agnatha have one class Cyclostomata.
II.
Gnathostomata is divided into two super
- classes.
1.
Pisces (bear fins)
2.
Tetrapoda (Bear limbs)
Pisces are divided into two sub - classes.
1)
Chondrichthyes (Cartilaginous fishes)
2)
Osteichthyes. (Bony fishes)
Tetrapoda is divided into four sub—classes
Sub - phylum Vertebrata
i.
(i) Amphibia (ii) Reptilia (iii) Aves (iv)
They are bilaterally symmetrical, trip-
loblastic coelomates.
ii.
Mammalia
Division 1—Agnatha
Notochord is only an embryonic structure. In the adult it is replaced by the
I.
with a Cirucular mouth.
Vertebral column (backbone. )
iii.
Dorsal hollow central nervous system is
Agnathans are Jawless aquatic vertbrates
II.
It has a single class - cyclostomata.
differentiated into brain and spinal cord.
iv.
Two pairs of lateral appendages are pre
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You may learn slowly but don't go back • 296 .
Class - Cyclostomata (round mouthed
Tetrapoda.
fishes).
Super Class 1 Pisces (fishes)
I.
All are ectoparasites on some fishes.
II.
They have sucking and circular mouth
•
without jaws.
III.
IV.
They have an elongated body bearing 6 –
Their body is devoid of scales and paired
Cranium and vertebral column are Carti
laginous.
VI.
It is divided into 2 Classes - Chondrichthyes and Osteichthyes.
Class 1 Chondrichthyes (Cartilaginous fish-
fins.
V.
locomotion.
•
15 pairs of gill slits for respiration.
It Consists of Fishes. They bear fins for
es)
I.
They are marine animals.
II.
Cold - blooded (poikilothermic) ani
mals. They have no capacity to regulate
Circulation is of closed type.
their body temperature skin is tough and
is covered by placoid scales.
VII. Cyclostomes are marine but for spawn
ing to fresh water.
III.
are backwardly directed.
Examples: Petromyzon (Lamprey) and
Myxine (Hagfish).
Teeth are modified placoid scales which
IV.
Endoskeleton is Cartilaginous.
I.
Notochord is persistent
throughout
life.
II.
Mouth is half moon shaped (crescentic)
and Ventral in Position.
III.
Heart is two—chambered (one auricle
and one ventricle).
Division 2 - Gnathostomata
•
Gnathostomates
possess
IV.
Jaws
and
ulate buoyancy (floating) is absent So,
paired appendages.
•
these fishes have to Swim continuously
(Constantly ) to prevent (avoid) sinking
Notochord is usually replaced by a Ver-
to the bottom.
tebral column.
•
Division Gnathostomata is divided into 2
super Classes - Pisces (fishes ) and
Plus 1 Biology
Air bladder (swim bladder ) Which reg-
V.
Paired kidneys excrete nitrogeneous
waste in the form of urea (ureotelic)
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Sooner you start sooner you gain • 297 .
VI.
They are diecious (sexes are separate).
XI
Paired copulatory organs called
clasp-
ers are present between the base
of the
pelvic fins in males.
XII. Fertilization is internal .
Examples: Scoliodon (Dog fish), Pristis
and one ventricle).
VII. They are cold—blooded animals.
VIII. Sexes are separate
IX.
Fertilisation is usually external
X.
They are mostly oviparous and devel
opment is direct.
(Saw fish), Carcharodon (Great white
Examples: Marine - Exocoetus (Flying
shark), Trygon (Sting ray).
fish), Hippocampus (Sea horse): Fresh
water Labeo (Rohu), Catla (Katla),
Clarias (Magur):
(Fighting fish),
Aquarium Betta
Pterophyllum (Angel
fish)
Class 2 - Osteichthyes (bony fishes)
I.
Marine and fresh water fishes.
II.
Endoskeleton is bony,
III.
Mouth is terminal .
They have four pairs of gills which are
covered by and operculum on each side.
IV. Skin is covered with cycloid / ctenoid
V.
VI.
scales.
SUPER CLASS 2 TETRAPODA
Air bladder is present which regulates
I.
Tetrapodes have 2 pairs of limbs.
buoyancy.
II.
They are divided into 4 Classes—
Heart is two - chambered (one auricle
Plus 1 Biology
Amphibia, Reptilia, Aves, and Mam-
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Learning is a good habit to success • 298 .
malia.
Class 1 Amphibia
I.
They are cold - blooded, amphibious
Vertebrates
which can live in Water
(aquatic and on land (terrestrial ).
II.
Most of them have two pairs of limbs.
Body is divisible into head and trunk.
III.
Tail may be present in some.
IV.
The skin is moist (without scales).
V.
The eyes have eyelids.
VI.
A tympanum represents the ear.
VII. Alimentary canal, urinary and reproduc-
Class 2 Reptilia
•
tebrates.
tive tracts open into a common chamber
called cloaca which opens to the exteri-
•
or.
They are teresstrial , Cold - blooded
(poikilotherms) and oviparous vertebrates.
VIII. Respiration is by gills, lungs and through
skin
IX.
Reptiles are creeping (crawling ) ver-
•
The skin is dry
and non - glandular
The heart is three—chambered (two
(cornified) having an exoskeletal cover-
auricles and one ventricle)
ing of epidermal scales which form a
water - proof coat on the body.
X.
Sexes are separate.
XI.
Fertilisation is external
•
cast, eg: snakes and lizards.
XII. They are oviparous and development is
indirect.
Examples: Bufo (Toad), Rana Frog),
Hyla
(Tree
frog),
•
Limbs, when present, are two pairs.
•
The heart is imperfectly 3—chambered
with two auricles and an incompletely
Salamandra
divided ventricle. In Crocodile, heart is
(Salamande), Ichthyophis (limbless am
4 - chambered.
phibia).
Plus 1 Biology
Some reptiles shed their scales as skin
•
External ear is absent.
•
Tympanum represents the ear.
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Animal kingdom
Take responsibility for your progress • 299 .
•
Sexes are separate. Fertilisation is inter-
•
nal.
•
for flight.
Development is direct.
Examples: Chelon (Turtle).
The fore - limbs are modified into wings
The hind—limbs are variously modified for
Testudo
(Tortoise), chameleon (Tree lizard), Ca
lotes Garden lizard), (Crocodilus), Alli
gator (Alligator), Hemidactylus (wall
lizard, Poisonous snakes - Naja (Cobra),
Bangarus (Krait), Vipera (Viper).
walking, swimming or clasping on tree branches.
•
The jaws are modified as beak or bill.
•
Endoskeleton is fully ossified (bony)
•
Bones are light, porous and air—filled
(pneumatic) in order to reduce the body
weight,
porous
and
air
-
filled
(pneumatic) in order to reduce the body
weight.
•
Skin is dry without glands except the
oil gland at the base of the tail.
•
The heart is 4—chambered.
•
Digestive system has additional chambers - crop and gizzard.
•
Respiration by lungs.
•
Air sacs connected to lungs supplement
respiration.
Class 3 Aves
•
They are characterized by the presence
of feathers.
•
Most of them can fly except flightless
birds. (eg: Ostrich)
•
They are aerial, warm
•
Sexes are separate.
•
Fertilization is internal.
Examples: Corvus (Crow).
Columba
(pigeon), Psittacula (Parrot), Struthio
(Ostrich ), Pavo (Peacock),
- blooded
(Homoiotherms ) and oviparous vertebrates.
•
The body has an exoskeleton of feathers
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Animal kingdom
Punctuality is respecting your own commitments • 300 .
X.
Viviparous
Platypus and echidna are the only two egg laying mammals
Examples:
Oviparous - Ornithorhynchus(Platypus)
Viviparous - Macropus (Kangaroo) , Camelus
(camel), Macaca (Monkey), Rattus(Rats), Ca-
nis (Dog), Felis (Cat), Elephas (Elephant),
Balaenoptera (Blue whale), Panthera leo (Lion)
Class 4 Mammalia
I.
Skin is provided with hairs
II.
External ear or pinna is present.
III.
Presence of milk producing mammary
glands.
In females these glands secrete
milk for the nourishment of the young.
IV.
They have two pairs of limbs, adapted
for walking, running, climbing, burrowing, swimming or flying.
V.
Different types of teeth present in the
IMPORTANT QUESTIONS
jaw.
VI.
1.
Heart is four chambered.
VII. Respiration by lungs.
VIII. They
are
homoiothermous
(warm
blooded)
IX.
Sexes are separate, fertilization is inter-
Observe the picture A and B.
a)
Identify the phylum of A and B.
b)
Comment on the symmetry.
c)
Compare the type of coelom in A
and B.
nal
Plus 1 Biology
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Animal kingdom
Be afraid not to try • 301 .
4.
Fill the blank space in the table given
below.
Orgn / Struc- Function
ture
(a)….
Rasping organ in Mol-
luscs
A
2.
B
(b) ….
Stinging cap-
Identify the cell, Name the phylum to
sule of Cni-
which it belongs?
daria
Who am I ?

I live in the sea.

I have organ—system level of organiza-
a.
Phylum in which flatworms are included.
b.
Excretory organs of annelids.
c.
Largest Phylum.
d.
An oviparous mammal.
e.
Chordate animal having flame cells as
6.
tion.

I respire through gills

I excrete by proboscis gland.

My body is composed of proboscis, collar and a long trunk.
Plus 1Biology
Name the following:
the excretory organ
3.
a) Name the phyla
5.
Complete the table,
A
B
C
Collar cells
…(a) ..
Digestion
(b) …..
Echinodermata
Locomotion
…..
Arthropoda
…(c) .
Radula
(d)…...
Feeding
b) give one example
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Animal kingdom
Be a student in life to learn something new • 302 .
7.
A shark has to swim continuously unlike
13.
a sardine. Give reason.
8.
ed two organisms. Observing the morphology, it is clear that the organisms are
Bats and whales belong to the same
radially symmetrical.
class.
a)
b) Give reasons
But all
b)
which the other organisms can be include
statement with an example.
ed.
Your are given the Specimens of Scolio
c)
don and Catla. Distinguish between
organisms will help you to categories it
these two, on the basis of the following
into a particular phylum?
14.
Which distinctive feature of this
“All vertebrates are chordates but all
(a) Operculum (b) scales (c) air bladder
chordates are not vertebrates "Evaluate
(d) fertilization
and substantiate the statement.
Name the following .
15.
b)
Name
the
distinctive
character
(responsible for their names) of the fol
a) An egg laying mammal.
lowing animal groups:
A flying mammal
PREVIOUS YEARS QUESTIONS
12.
Identify the possible phyla to
chordates are not vertebrates. Justify this
features.
11.
To which phylum does this organ
ism belong?
All vertebrates are chordates.
10.
One of them
shows bioluminescence.
a) Identify the class
9.
During a seashore visit, a student collect-
(a) Pick out the acoelomate organism
from the following:
i)
Roundworm
ii) Hookworm
iii)
Filarial worm
iv) Tapeworm
a) Cnidaria
b) Arthropoda
c) Porifera
d) Annelida
e) Chordata
f) Ctenophora
Or
Your Biology teacher exhibited a laboratory specimen in the classroom. Based
b)Name the phylum to which it belongs.
on which features will you distinguish it
c)Mention its mode of nutrition.
as a chordate or a non - chordate?
d)
What is the coelomic condition of
other organisms?
swer.
Substantiate your an-
16.
Prawns and insects are included in the
phylum Arthropoda while they have dif
ferent habits and habitats. Justify your
answer.
Plus 1 Biology
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Be afraid not to try • 303 .
17.
Figures (X) and (Y) are the fish of two
22.
different classes. Identify them and dif
The following diagram shows the charac
teristic features of a phylum.
ferentiate between these classes.
a)
Identify the phylum.
b)
Mention four salient features of
this phylum.
X
Y
18.
Birds are well adapted for flying. Give
23.
with A.
any three of such adaptations.
A
B
C
Phylum /
Class
Common
example
Unique feature
statement with an example.
Pisces
Aedes
Presence of
hair
The characteristic features of an inverte
Mammalia
Leech
Open circulatory system
Arthropoda
Felis
Presence of
two - chambered heart
Scoliodon
Presence of
Nephridia
Or
All vertebrates are Chordates, but all
chordates are not vertebrates. Justify this
19.
Match the items in columns B and C
brate is given.
“The phylum includes the comb jellies,
also called walnuts. They are noted for
their bioluminescence and comb plates”.
Identify the phylum.
20.
Fill in the blanks with appropriate word:
Osteichthyes : Cycloid scales
24.
Chondrichthyes : ———
21.
—have pseudocoelom.
Name the phyla in which the following
cells / Structures / organs are present:
a) Radula
c) Pneumatic bone
Plus 1 Biology
Among the different phyla of animals —
b) Cnidoblast
25.
Categories the following animals under
radial symmetry and bilateral symmetry
- Physalia, Tapeworm, Fasciola, Ad
amsia
d) Proboscis gland
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Animal kingdom
Be afraid not to try • 304 .
26.
Note the relationship in the first pair and
then complete the second pair.
Osteichthyes :
Cycloid scales
Chondrichthyes : ———
27.
Arrange the following terms under two
headings based on symmetry.
Arthropods,
Ctenophores, Molluscs,
Coelenterates.
28.
31.
Complete the flow chart given below.
32.
Find the odd one from each group. Justi
(a) A table showing examples of verte
brates is given below. But some of the
examples are wrongly given.
Identify
and rearrange it.
Pisces
Am-
Reptilia Aves
phibia
Dog
Frog
malia
Vulture Pen-
fish
Blue
Rohu
whale
MamAlliga-
guin
tor
Tor-
Sala-
Flying
toise
mander fox
(b) Which of the above mentioned class
is characterized by the presence of pneu
matic bones?
29.
“All vertebrates are chordates; but all
chordates are not vertebrates”. Do you
agree with this statement? Substantiate.
30.
Observe the figure of the organism given
below.
fy your answer.
a)
Identify the organism.
b)
Name the class in which it belongs.
c)
Mention any two salient features of
the class.
Plus 1 Biology
a)
Star fish, Devil fish, Dog fish, Jelly fish
b)
Flying fish, Angel fish, Saw fish,
Fighting fish.
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Be a student in life to learn something new • 305 .
c)
Sea lily, Sea cucumber, , Sea hare, Sea
urchin.
33.
a.
Identify the organisms A,B and C.
b.
Name the phylum to which each of
Identify the word pair applicable to ph
them belong.
ylum Ctenophora.
(a) Nephridia, Parapodia
ANSWERS
(b) Comb plates, Bioluminescence
(c) Polyp, Metagenesis
1.
(d) Radula, Visceral hump
34.
b) A—Radial Symmetry. B—Bilateral
Characteristics of certain animals are
sym metry.
given.
c) A—Acoelomate. B - True coelomate.
Arrange them under the ‘Class’ to which
these animals belong.
i.
Skin is moist without scales.
ii.
Body is covered by dry and corni
2.
Cnidoblast. Phylum - Coelenterata
3.
a) Phylum - Hemichordata
b) Balanoglossus
fied skin.
4.
a) Radula
iii.
Shed the scales as skin cast.
5.
a) Phylum - Platyhelminthes
iv.
Can live in aquatic as well as ter
b) Cnidoblast
b) Nephridia
restrial habitats.
35.
a) A—Coelenterata. B - Annelida.
c) Phylum - Chordata
Observe the figures.
d) Platypus
e) Amphioxus
6.
a) Porifera
b) Tube feet
c) Respiration d) Mollusca
7.
Because, sharks do not have swim bladder (air bladder) to regulate buoyancy.
8.
A
B
C
a) Class Mammalia.
b) 1. They are viviparous vertebrates.
2. The respiratory system, excretory
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Keep calm and respect others • 306 .
c) Based on presence or absence of tube
system, nervous system and reproductive
9.
system are well - developed.
feet, spiny exoskeleton, tentacles, nema
All chordates have a notochord but not
can categories the second organism into
vertebral column.
its particular phylum.
tocyst, shape (e.g., Star shape), etc., We
In vertebrates noto
chord is replaced by vertebral column.
Chordates are classified into urochord
14.
embryonic stage. But all chordates lack
dates, cephalochordates and vertebrates.
vertebral column. Chordates like Uro-
In urochordates and cephalochordates a
chordata and cephalochordate lack verte-
‘no - tochord’ is present. It persists in
bral column. Vertebrates are chordates
cephalochordates and disappears in the
with vertebral column.
adult of urochordates.
15.
10.
Features
1)
Scoliodon
Opercu- Absent
All vertebrates have notochord in the
A) Cnidoblast / Stinging cells
B) Jointed foot
Catla
Present
C) Porous body
D) Metamerism / Segmented
2) Scales
Placoid
Cycloid
scales
scales
3) Air blad- Absent
Present
E) Notochord
F) Comb plates
Or
4) Fertiliza- Internal
External
tion
Differences between chordates and non chordates
11.
a) Platypus
12.
a) Tapeworm
b) Bats
b) Phylum Platyhelminthes
c) Parasitic
d) All are pseudocoelomate.
13.
a) Phylum Ctenophora
b) Coelenterata (Cnidaria)
Or Echino
dermata
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Learn and share from your heart • 307 .
Chordata
Non - Chor-
Notochord
Present
Nerve cord
Dorsal tubu- Double ven-
Absent
lar
tral
Present
Absent
Post anal tail Present
Absent
Gill slits
18.
•
Presence of wings
•
Body is covered by feathers
•
Pneumatic bones
Or
All vertebrates have notochord in the
embryonic stage. But all chordates lack
vertebral column.
Chordates like Uro
chordata and cephalochordate lack verte
bral column. Vertebrates are chordates
16.
Both insects and prawns have:
with vertebral column. Man is an exam
1.
Jointed appendages
ple for vertebrate.
2.
Haemocoel present
19.
Ctenophora
3.
Segmented body with head, thorax and
20.
Placoid Scales
abdomen.
21.
A) Mollusca
17.
B) Cnidaria / Coelenterata
Chondrichthyes
Osteichthyes
C) Chordata / Aves - Birds
1. Endoskeleton is
cartilage
1. Bony endoskeleton
D) Hemichordata.
2. Five pairs of
gills without operculum
2. Four pairs of
gills operculum
22.
b) (i) Presence of dorsal hollow nerve
cord
3. Mouth is ventral 3. Mouth is terminal
4. Heterocercal
caudal fin
(ii) Presence of notochord
4. Homocercal caudal fin
(iii) Presence of paired pharyngeal gill
slits.
5. Body is covered 5. Body is covered
by placoid scales
by ctenoid scales
6. Air bladder absent
6. Air bladder present.
7. Fertilization is
internal
7. Fertilization is
external
Plus 1 Biology
a) Phylum Chordata
(iv) Presence of post anal tail
23.
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Animal kingdom
You become what you study • 308 .
dates with vertebral column.
A
B
C
Pisces
Scoliodon
Presence of
two - cham-
Mammalia
Felis
Presence of
hair
Arthropoda
Aedes
Open circulatory system
30.
A) Hippocampus / Seahorse
B) Class Osteichthyes
C) Bony endoskeleton
Presence of air bladder
31.
a) Gnathostomata b) Cyclostomata
c) Tetrapoda
24.
Aschelminthes
25.
Radial symmetry : Physalia, Adamsia
32.
d) Osteichthyes
a) Dog fish - Dog fish belongs to phylum
Chordata which is characterized by presence of notochord.
Bilateral symmetry : Tapeworm, Fasciola
Others are non—
chordates.
26.
Placoid scales
27.
Radial Symmetry : - Ctenophores, Coe-
drichthyes
lenterates
maining are Osteichthyes (bony fishes).
Bilateral symmetry : - Arthropods, Mol
c) Sea hare - Phylum Mollusca, Remain
luscs.
ing ones - Phylum Echinodermata
28.
b) Saw fish - Belongs to Class Chon
(a)
Pisces
Dog
Am-
Reptil- Aves
Mam-
phibia
ia
malia
Frog
Alliga- Pen-
Blue
tor
guin
whale
Tor-
Vulture Flying
fish
Rohu
Sala-
mander toise
fox
33.
b) Comb plates, Bioluminescence
34.
Class Amphibia (i) & (iv)
Class Reptilia (ii) & (iii)
35.
A - Balanogloussus - Phylum Hemichordata
B - Nereis - Phylum Annelida
C - Liver Fluke / Fasciola - Phylum Plat
(b) Class - Aves / Birds
29.
( Cartilaginous fishes). Re
yhelminthes (Flat worms.)
Yes. All vertebrates have notochord in
the embryonic stage. But all chordates
lack vertebral column.
Chordates like
Urochordata and cephalochordate lack
vertebral column. Vertebrates are chorPlus 1 Biology
Winner’s Coaching Centre
Animal kingdom
I’m proud of the way you worked today • 309 .
CHAPTER - 5
MORPHOLOGY OF FLOWERING PLANTS
Morphology is the branch of biology, which
deals with the study of external form and structure.
1.
Tap root system
•
The primary root and its branches constitute the tap root system.
The flowering plants are collectively called as
angiosperms.
•
The tap root system has a main root
called taproot or primary root. It is the
Parts of a flowering plant
direct prolongation of the radicle.
A typical flowering plant has following two
•
The root system is characteristic of dicotyledons eg. Mustard plant.
parts.
The root system—It is underground part, usu-
2.
Fibrous root system
ally below the soil. It originates from the radi-
•
Monocots have fibrous root system.
•
The primary root dies off early, Later
cle of the embryo.
The shoot system - It is the aerial, usually
numerous hair like roots arise from the
above the soil. It originates from the plumule
base of the stem.
of the embryo.
•
All the fibrous roots are thin. They do
Root
not grow into the deep soil. Eg. , Wheat
I.
It is positively geotropic.
plant.
II.
On germination of a seed, the first root
arises from the radicle of the embryo and
3.
Adventitious root system
•
These roots arise from any part of the
grows downwards. This is called as the
plant other than the radicle,
Primary root.
III.
Eg: grass. Monstera, banyan tree etc..
It bears lateral roots of several orders
that are known as Secondary, tertiary
roots etc.
There are three types of root systems. They
Functions of the root system
1.
To anchor the plant to the soil.
2.
To absorb water and nutrients from the
are taproot system, fibrous root system and
adventitious root system.
Plus 1 Biology
soil.
3.
Storing reserve food materials.
Winner’s Coaching Centre
Morphology of flowering plant
I’m proud of the way you worked today • 310 .
4.
Synthesis of plant growth regulators
5.
Some roots get modified to perform spe-
tion is called the region of maturation.
•
From this region some of the epidermal
cial functions such as respiration, me-
cells form very fine and delicate, thread
chanical support, assimilation and
like structures called root hairs.
storage of food.
root hairs absorb water and minerals
The
from the soil.
Regions of the root
THE STEM
I.
Stem bears branches, leaves, flowers
and fruits.
II.
The stem bears nodes and internodes.
III.
The region of the stem where leaves are
born are called nodes.
IV.
Region between two adjacent nodes is
termed internode.
Functions of the stem
I.
It acts as a supporting structure for the
1.
Root cap (Calyptra)
branches which bear leaves, flowers and
•
The tip of the root is protected by a thim-
fruits and expose them to sunlight.
ble like structure called root cap.
II.
It protects the tender root apex as it
III. In many plants the stem is modified for
makes its why through the soil.
doing special functions such as storage of
2.
Meristematic region
food, support protection and vegetative propa-
•
This region occupies a few millimeters
•
•
It conducts water, minerals.
gation.
above the root cap.
THE LEAF
The cells of this region are very small,
I.
thin walled and with dense cytoplasm.
The cells divide repeatedly.
Region of Maturation
•
The zone proximal to region of elonga-
Plus 1 Biology
outgrowth borne on the stem.
II.
3.
The leaf is a lateral generally flattened
It develops at the node and bears a bud in
its axil called axillary bud. The axillary bud later develops into a branch.
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Morphology of flowering plant
Keep working on it, you’re almost there! • 311 .
III.
They are the most important vegetative
organs since they are adapted for performing the vital functions such as transpiration, Photosynthesis respiration.
called lamina or leaf blade.
•
The lamina bears veins and veinlets.
•
There is a middle prominent vein
known as Midrib.
Parts of a Leaf
•
Veins provide rigidity to the leaf blade
A typical leaf consists of three parts a leaf
and act as channels of transport of wa-
base, Petiole and lamina.
ter, minerals and food materials.
Leaf base (Hypopodium)
•
•
•
The basal part of the leaf that connects it
The edge of lamina is known as leaf
with the stem is called leaf base.
margin.
Small lateral outgrowths are developed
on either side of the leaf base, called the
stipules.
•
Venation
The mode of arrangement of the veins and
veinlets in the lamina is called venation.
In monocotyledons the leaf base expands
in to a sheath covering the stem partially
•
The tip of the leaf is called leaf apex.
The venation is of two types.
or wholly. This is called sheathing leaf
Reticulate venation
base.
In reticulate venation the veinlets form a net-
In some leguminous plants the leaf base
work. It is a characteristic feature of dicotyle-
may become swollen, which is called
dons.
pulvinus.
Eg: Hibiscus, Cucumber.
Petiole (Mesopodium)
Parallel venation
•
The stalk of the leaf is called the Petiole.
When the veins run parallel to each other
•
A leaf having petiole is called Petiolate.
within a lamina, the venation is called paral-
•
The leaf without the petiole is called Ses-
It is a characteristic feature of monocotyle-
sile.
•
lel.
The petiole help to hold the leaf blade to
dons.
Eg: Banana, grasses etc.
light.
Lamina or leaf blade (Epipodium)
•
The green, expanded part of the leaf is
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Morphology of flowering plant
Nothing can stop you now • 312 .
In pinnately compound leaf the leaflets are arranged at the tip of the rachis, like the fingers
in our palm.
Eg: Silk cotton
Types of leaves
Leaves are of two types.
They are simple
leaves and compound leaves.
Phyllotaxy
1. Simple leaves
A leaf with single lamina is said to be simple
leaf.
The pattern of arrangement of the leaves on the
stem is called Phyllotaxy.
types - Alternate, Opposite and Whorled.
Eg: Hibiscus.
Alternate phyllotaxy.
2. Compound leaves
Here a single leaf arises at each node in alter-
A leaf with two or more lamina or leaf segments is called a compound leaf.
nate manner.
Eg: China rose, mustard, sunflower
These leaf segments are called leaflets.
Compound leaves are of two types.
Opposite phyllotaxy
Here a pair of leaves arise at each node and lie
Pinnately compound leaf
opposite to each other.
In pinnately compound leaf a number of leaf-
Eg: Calotropis, guava plants
lets are present in a common axis called rachis, which represents the midrib of a leaf.
Eg: Neem tree.
Palmately compound leaf
Plus 1 Biology
This is of three
Whorled Phyllotaxy
If more than two leaves arise at a node and
form a whorl, It is called whorled phyllotaxy.
Eg: Alstonia
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Morphology of flowering plant
Whatever you do, do it well • 313 .
INFLORESCENCE
An axis bearing a cluster of flowers are known
as inflorescence.
Cymose inflorescence
In Cymose inflorescence peduncle terminates
Eg: Crotalaria.
in a flower.
The common axis of the inflorescence is called
The terminal flowers are arranged laterally
peduncle.
towards the base. This type of development
The flowers may arise from the axil of leaf like
is called basipetal succession.
structure called bract.
FLOWER
Based on the nature of the peduncle the inflo-
•
unit in the angiospersms.
rescence may be divided into two groups. They
are racemose and cymose.
•
A flower is a modified reproductive
shoot. The stalk of the flower is called
Racemose inflorescence
pedicel.
The peduncle does not terminate in a flower.
The peduncle tip continues growing and pro-
•
the younger flowers near the tip and the
older flowers at the base. This development
The upper part of the pedicel is swollen
or flattened and is known as Thalamus.
duces flowers laterally. The peduncle bears
•
The thalamus bears four floral whorls.
They are calyx, corolla, androecium
of flowers is called acropetal succession.
Plus 1 Biology
The flower is the sexual reproductive
and gynoecium.

Calyx: Composed of sepals

Corolla: composed of petals
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Morphology of flowering plant
Every moment is a fresh beginning • 314 .


Androecium: Composed of stamens
Bracteate - A flower with a bract (bract is a
(male reproductive part)
reduced leaf found at the base of the pedicel)
Gynoecium:
Composed
of
carpels
(Female reproductive part)
Ebracteate - A flower without a bract.
Position of floral leaves on the thalamus
Terms for describing a flower
Based on the position of floral leaves on the
Bisexual - A flower with both androecium and
thalamus flowers may be of following three
gynoecium.
types.
Unisexual - A flower with only androecium or
1. Hypogynous Flower.
gynoecium
Actinomorphic (Radial symmetry ) - A flower
that can be divided into two equal radial halves
•
The ovary is located at the top.
•
Here the other floral parts such as calyx
corolla and androecium are attached to
in any radial plane passing through the centre.
Eg: Mustard, Datura, Chilli etc.
the thalamus below the ovary.
•
Zygomaorphic - A flower that can be divided
The ovary is superior
Eg: Mustard , China rose and Brinjal
into two equal halves only in one vertical
plane.
2.
Perigynous flower
Eg: Pea, Gul mohar. Bean, Cassia etc.
•
The ovary is situated at the bottom of the
concave thalamus without fusing with
Asymmetric (irregular) - A flower that cannot
other floral parts such as calyx, corolla
be divided into two similar halves by any verti-
and androecium.
cal plane passing through the centre.
•
Eg: Canna
The ovary is said to be half inferior.
E.g: Plum, Rose, Peach etc.
Trimerous - A flower in which number of
parts in each whorl is 3 or its multiple.
3. Epigynous flower
Eg: Monocots
•
and is fused with the ovary.
Tetramerous –A flower in which number of
parts in each whorl is 4 or its multiple.
•
Eg: In most dicots
Plus 1 Biology
The other parts of the flower arise above
the ovary.
Pentamerous - A flower in which number of
parts in each whorl is 5 or its multiple.
Thalamus become deeply cup - shaped
•
The ovary is inferior .
Eg: Guava, Cucumber and the ray flo
Winner’s Coaching Centre
Morphology of flowering plant
There is no substitute for hard work • 315 .
rets of Sunflower.
•
The corolla is the second whorl of a
flower inner to the calyx.
•
It is composed of petals. The petals are
brightly coloured to attract insects for
pollination
•
When the petals are free the corlla is
termed Polypetalous.
If the petals are
fused, the corolla is termed gamopetalus.
Aestivation
The mode of arrangement of sepals or petals
Parts of a Flower
Each flower has four whorls. They are Calyx,
Corolla, Androecium and
Gynoecium.
in a flower bud is called aestivation.
The main types of aestivation are valvate,
twisted,
imbricate
and
vexillary.
Calyx
•
The calyx is the outermost whorl of a
flower.
•
It is composed of Sepals.
•
Sepals are green, leaf like, They protect
the flower in bud stage.
•
When the sepals are free the calyx is
said to be Polysepalous. If the sepals are
fused, the calyx is said to be gamosepalous.
Corolla
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Morphology of flowering plant
Whatever you are, be a good one • 316 .
als (wings) which
in turn overlap the
two smallest anterior petals (keel),
Eg: Pea and bean flowers.
Valvate aestivation
When the edges of sepals or petals just meet
one another without overlapping, the aestivation is known as valvate.
Eg: Calotropis
Androecium
Twisted aestivation.
•
If one margin of an appendage overlaps that of
The androecium is the third whorl inner to the corolla.
the next one and so on, it is called twisted aes•
tivation.
men is the male reproductive part of
Eg: China rose, Lady’s finger and cotton.
Imbriacate aestivation
the flower.
•
If the margins of sepals or petals overlaps one
•
Each anther is usually bilobed and
each lobe has two chambers, the pol-
Here one of the appendages is completely in-
side, One Completely outside
Each stamen has a slender stalk called
the filament and an anther.
another but not in any particular direction, it is
called imbricate aestivation.
It is composed of stamens. The sta-
len sacs. The pollen grains are pro-
and the re-
duced in pollen sacs.
maining ones regularly overlaps.
Eg: Cassia and gulmohur.
Vexillary aestivation (Papilionaceous aestiva-
Adhesion of stamens
tion)
Stamens may be united with the other mem-
•
Here there are five petals; the largest
bers such as petals, sepals or gynoecium.
(Standard) overlaps the two lateral pet-
1.
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Epipetalous: The stamens are fused with
Winner’s Coaching Centre
Morphology of flowering plant
Education is the key to success • 317 .
the petals . Eg: Brinjal.
2.
•
is said to be apocarpous.
Epiphyllous: The stamens attached to
the perianth. Eg: Lily.
Eg: - lotus and rose.
Cohesion of stamens
•
If all the stamens in a
flower are free, the androecium is said to be
Polyandrous.
The fusion of stamens may be
Eg: Mustard and tomato.
Placentation
•
of following types,
The mode of arrangement of ovules on
the placenta within the ovary is known as
Monadelphous: All the filaments of stamens
placentation.
are fused to form a single bundle.
•
Eg: China rose
If the carpels are fused it is called syncarpous gynoecium.
Fusion of the members of the similar whorls
is called cohesion.
If the carpels in a gynoecium are free, it
The different type of placentation is as
follows.
Diadelphous: The filaments of stamens are
fused to form two bundles.
Marginal placentation
The ovary is one chambered (unilocular). The
Eg: Pea
placenta forms a ridge along the ventral suture
Polyadelphous: The filaments of stamens are
of the ovary and the ovules born on this ridge
fused to form many bundles.
forming two rows.
Eg: Citrus.
Eg: - Pea
Gynoecium
Axile placentation
•
•
Gynoecium is the innermost whorl of a
It is found in multicarpellary syncarpous and
flower.
multilocular ovary. The placenta bearing the
It is the female reproductive part of the
flower.
It is composed of carpels.
•
Each carpel has an ovary, style and stig-
The basal swollen ovary encloses the
ovules. Stigma is the receptive surface
Plus 1 Biology
Parietal Placentation
It is usually seen multicarpellary and syncar-
ma.
of pollen grains.
ovary .
Eg: - China rose.
•
•
ovules develop from the central axis of the
pous pistil.
The Basal ovary is unilocular.
The ovules on the placenta are originated at the
point of fusion of the margins of the carpels
Winner’s Coaching Centre
Morphology of flowering plant
There is no substitute for hard work • 318 .
on the inner surface of the ovary. The one
chambered ovary may become two chambered
due to the formation of the false septum.
Drupe
Drupe is a simple fleshy one seeded fruit developed from monocarpellary superior ova-
Eg: Mustard and Angemone
ry.
Free - central placentation
Where the Pericarp is differentiated into outer
Ovary is unilocular and placenta arises from
the base of the ovary , Projects in to the cavity
epicarp. Middle mesocarp and inner endocarp.
Eg: Mango, Cocunut, [Edible portion of man-
as a swollen axis and bears ovules.
go is the mesocarp]
Eg: Dianthus and Primerose
Basal Placentation
Ovary is unilocular. The placenta develops at
the base of the ovary and bears a single ovule.
Eg: Sunflower, Marigold
SEED
The seed is a mature ovule containing embryo.
Seeds are of two types.
(i) Endospermous seeds and (ii) non endo-
FRUIT
A fruit is a ripened ovary developed after ferti-
sperms seeds.
lization.
Endosperms seeds: A seed with endo-
Parathenocarpic fruit
sperm is called Albuminous seed.
A fruit formed without ferilisation is called
Food is stored in the endosperm.
parthenocarpic fruit
Eg: Wheat, maize, barley, castor, sunflower
Structure of fruit.
etc.
Fruit consists of outer pericarp and inner
Non endosperms seeds: A seed without
seed. Pericarp is differentiated into outer epi-
endosperm is called non albuminous seed.
carp, middle mesocarp and inner endocarp.
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Eg: pea, groundnut, beans, sunflower, cash-
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Morphology of flowering plant
Strive for learning and not for grades • 319 .
ew nut etc.
Structure of Dicotyledonous seed
•
Seed coat is the outermost layer of the
seed having two layers, outer testa and
inner tegmen.
•
Hilum
is a scar on the seed coat by
which the developing seeds are attached
to fruit.
•
Micropyle is a small pore above hilum.
•
Embryo is present inside seed coat with
embryonal axis and two cotyledons.
Semi - technical description of a typical
•
Cotyledons are fleshy and consist of reserve food materials.
•
Floral Diagram
Two ends of embryonal axis bear redicle
and plumule.
Monocot seeds may be endospermous
or non endospermous.
•
The diagrammatic representation of floral
parts in a flower bud is called Floral diagram.
Structure of Monocotyledonous seed
•
flowering plant foral Diagram
Floral Formula
The representation of floral parts with their
appropriate symbols is called floral formula
Seed coat is membranous and fused with
fruit wall.
•
Aleurone layer is the proteinaceous layer separating embryo and endosperm.
•
Embryo is small and consists of one
large shield shaped cotyledon called axis
with a plumule and radicle.
•
Plumule and radicle are enclosed in
sheaths called coleoptile and coleorhiza.
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Morphology of flowering plant
Be better than yesterday • 320 .
aestivation
Corolla: Petals five, united; valvate aestivation
Androecium: stamens five, epipetalous
Gynoecium: bicarpellary, syncarpous; ovary
superior, bilocular, placenta swollen with
many ovules
Fruits: berry or capsule
Seeds: many, endosperms
Floral formula:
.
II. SOLANACEAE
It is a large family, commonly called as the
‘potato family’
Economic importance
Vegetative Characters
Edible plants
Plants mostly, herbs, shrubs and small trees
1.
Stem: herbaceous rarely woody Aerial, erect,
cylindrical, branched, solid or hollow hairy of
glabrous,
underground
stem
in
potato
(Solanum tuberosum)
Solanum tuberosum (potato): Stem tuber is used as food throughout the world.
Medicinal plants
1.
Atropa belladonna (belladonna): Atropin extracted from roots is used in the
Leaves: alternate, simple, rarely pinnately
preparation of
compound, exstipulate; venation reticulate
2.
Withania somnifera (ashwagandha):
Leaves are used in fever and skin diseas-
Floral Characters
es.
Inflorescence: Solitary, axillary or cymose as
in Solanum
Fumigatory plants
1.
Flower: bisexual, actinomorphic
Nicotiana tobacum (tobacco)
Ornamental plants
Calyx: Sepals five, united, persistent, Valvate
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Morphology of flowering plant
Always have an attitude of gratitude • 321 .
1.
Petunia violacea
a)
Food is stored by plants.
2.
Cestrum nocternum
b)
Leaves are born
c)
Xylem and phloem are present
d)
Axillary buds develop
4.
In which plant underground stem spreads
to new niches and when older parts die new
plants are formed.
a) Grasses
b) Strawberry
c) pistia
d) Both (a) and (b)
5. Petiole
IMPORTANT QUESTIONS
1.
Which of the following is incorrect?
a) Roots helps in water and mineral ab6.
sorption from soil.
a)
Helps to hold the leaf blade
b)
Allows leaf blades to flutter wind
c)
Helps in cooling the leaf
d)
All of the above
Perianth is the condition in which?
b) Roots provide a proper anchorage.
a) Calyx and corolla are not distinct
c) Roots store food material and syn-
b) Calyx is present, but corolla is ab
sent.
thesise plant growth regulators.
d) Roots lack meristematic activity.
2.
sent.
Which of the following is the smallest
d) Calyx and corolla are not present.
region of the root?
7. Fill in the blank.
a) Root cap
3.
c) Corolla is present, but calyx is ab
b) Region of elongation
Location of thalamus is …………….
c) Region of meristematic activity
a) Higher than other floral whorls
d) Region of maturation
b) Lower than other floral whorls
Nodes are the region of stem where
Plus 1 Biology
c) Same as the other floral whorls
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d) None of the above
8. Match the following
A. Pedicel
1. reduced leaf
B. Peduncle
2. Stalk of the flower
C. Bract
3. Stalk of the leaf
D. Petiole
4. Inflorescence ax14. The term ‘Polyadelphous’ is related to
9. How is pinnately compound leaf different
from palmately compound leaf?
10. Give the technical term of the following:
2. Flowers cannot be divided into two
equal halves.
4. Carpels are fused.
11. Justify the following statements on the basis of external features.
Underground parts are not always
roots.
Flower is a modified shoot.
12. Differentiate between
Racemose and cymose inflo-
Apocarpous and syncarpous ovary.
13. Label the regions of the root tip in the given diagram.
Plus 1 Biology
16. The wheat grain has an embryo with one
a)
Epiblast
b)
Coleorhiza
c)
Scutellum
d)
Coleoptile
17. Non - albuminous seed is produced in
a) Maize
b) Castor
c) Wheat
d) Pea
18. Which of the following is a correct combi-
rescence
2.
d) Citrus
large shield - shaped cotyledon known as
floral whorls.
1.
d) Calyx
a) Dianthus b) Argemone
c) Brassica
3. Position of ovary is higher than other
2.
c) Corolla
15. Free - Central placentation is found in
1. Two leaves at each node.
1.
a) Gynoecium b) Androecium
nation of family and its respective members
a) Fabaceae
- Tomato , chili
b) Solanaceae - Tobacco, Brinjal
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Take every problem as a challenge • 323 .
c) Liliaceae
- Petunia, potato
d) None of the above
c)
24.
Name the three kinds of petals in B.
Observe the figures A and B.
19. Endosperm, a product of double fertilization in angiosperms is absent in the seeds of
a) coconut
b) Orchids
c) Maize
d) Castor
20. Note the difference between the placenta
and thalamus.
A
21. Mango and coconut are ‘drupe’ type of
a)
fruits. Which are the 3 layers of pericarp.
b)
words and fill up the suitable word in the
25.
Define venation .
Write three peculiarities of gynoecium
seen in Solanaceae
1.
Shoot - Plumule : Root -
2.
Outer integument - Testa : Inner integ-
26. Observe the relationship between the
first two terms and fill in the blank.
ument 3.
Name the type of venation in A
and B.
22. Observe the relationship between first two
fourth place.
B
Epipetalous stamen - Brinjal
Ovule - Seed : Ovary -
———————— - Lily
PREVIOUS YEARS QUESTIONS
27. Match the following:
23. Observe the figures A and B .
A
(i) Vexillary
b) China rose
(ii) Valvate
c) Cassia
(iii) Twisted
d) Pea
(iv) Imbricate
28.
B
a)
Identify the aestivation A and B.
b)
Write one peculiarity of A.
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a) Calotropis
a) The arrangement of flowers on the
floral axis is called.
(i) Aestivation
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(ii) Phyllotaxy
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(iii) Placentation
(iv) Inflorescence
32. Use appropriate terms for the following
b) How can you differentiate an actino
29.
description :
morphic flower from a zygomorphic
A) Axillary buds of stems modified as
flower?
slender and spirally coiled structure for
helping plants to climb.
Observe the floral diagram and answer
the following questions:
B)
Axillary buds of sems modified as
woody straight and pointed structure to
protect plants from browsing animals.
33. Observe the diagram and answer the questions.
a) Name the family.
b) Write down the speciality of stamen.
30. The following figures show two type of
aestivation. Answer the following questions:
a)
Identify the types A and B.
b)
How will you distinguish A and
Name the aestivation given and write
one example for the same.
34. Name the parts of a monocot embryo in
the given diagram .
B?
31. Observe the following diagrams ‘a’
‘b’ . Identify the placentation.
and
1.
———
2.
———
3.
———
4.
———
35. Given below is the arrangement of petals
of a flower as drawn by your classmate.
A
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B
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ANSWERS
A) Identify the aestivation
1.
d) Roots lack meristematic activity
2.
c) Region of meristematic activity
3.
b) Leaves are born
flower is known as ———
4.
d) Both (a) and (b)
B)
5.
d) All of the above
6.
a) Calyx and corolla are not distinct
7.
b) Lower than other floral whorls
B) Give reason for the identification.
36. Fill in the blanks
A)
The arrangement of petals in the
Identify the types of the arrange
ment of petals shown in the following
diagrams:
8.
37. Bentham and Hooker’s Classification is
A. Pedicel
2. Stalk of the flower
B. Peduncle
4. Inflorescence axis
C. Bract
1. Reduced leaf
D. Petiole
3. stalk of the leaf
mainly based on ———
38. Arrangement of flowers on the peduncle
varies depending upon the nature and branching of the peduncle. Can you substantiate your
9
answer with suitable examples.
39. Identify the region ‘A’ marked in the figure and write down its function.
either side of a common axis, rachis, it is pinnately compound leaf. Rachis represents the
midrib of leaf. E.g. , Neem
10.
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When a number of leaflets are present on
Opposite phyllotaxy
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2. Asymmetric.
14. b) Androecium
3. Hypogynous flower.
15. a) Dianthus
4. Syncarpous.
16. c) Scutellum
11. Underground stem get modified for different purposes like food storage reproduction
and perennation. They can be recognized from
17. d) Pea
18. (b) Solanaceae - Tobacco, brinjal
root in having nodes, internodes , scale leaves,
19.
b) Orchids
terminal bud and axillary bud. E.g., Rhizome -
20. Placenta : Region with which ovules are
Ginger, Stem tuber - Potato.
attached to ovary.
2. A flower can be considered as a modified
Thalamus:
shoot because each whorl of a flower repre-
are attached.
sents each node. The leaves at each node is
modified to perform functions like protection,
attraction and reproduction.
21.Endosperm
The internodes
2. Liquid endosperm (free nuclear endo
are compressed to form a flower.
12.
1.
Racemose:
sperm)
The axis or peduncle
shows indefinite growth.
22. 1. Radicle
Flowers are
2. Tegmen
arranged in acropetal succession.
4. Fruit
Cymose: The axis or peduncle shows
definite growth or ends in a flower.
23. a) (A) Twisted
Flowers are arranged in basipetal success
(B) Vexillary / Papilionaceous
sion.
2.
(b) One margin of each member overlaps
Apocarpous: When the carpels of
that of the next one.
the ovary are free.
Syncarpous:
(c) Standard petal, wing (lateral) petals,
When the carpels of the
keel petals (anterior small petal).
ovary are fused.
13. a) Root cap
24. a) (A) Reticulate venation
(B) Parallel venation.
b) Meristematic region
b) Arrangement of veins and veinlets in
c) Region of elongation
d) Root hair region
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Region where floral parts
the leaf lamina.
25.
Solanaceae:
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Gynoecium -
Bicarpel
Morphology of flowering plant
Respect your parents, world will respect you • 327 .
lary , hypogynous, axile placentation,
bilocular, syncarpous, superior ovary,
swollen placenta, many ovules, G(2).
26. Epiphyllous / Epipetalous /Statements
attached to tepals or perianth
entation .
32.
(a) Tendrils (b) Thorns
33.
Vexillary aestivation e.g., Pea.
34.
1. Coleoptile
2. Plumule
3. Radicle
4. Coleorhiza
27.
a) Calotropis
35.
(ii) Valvate
(a) Imbricate
(b) Overlap one another in any particular
b) China rose
(iii) Twisted
c) Cassia
(iv) Imbricate
direction. One out, one in and others
half in and out.
36.
d) Pea
28.
(i) Vexillary
37.
(a) (iv) inflorescence
(a) Aestivation
(b) (A) Valvate
(B) Twisted
(C) Imbricate
(D) Vexillary
Vegetative characters and floral characters.
(b) Actinomorphic
Flower can be divided into two equal
radial halves in any radial plane passing
38.
The arrangement is of two types Racemose and Cymose.
In racemose, the peduncle does not ter-
through the centre.
minate in a flower.
Zygomorphic
It continuously
growing and produces flower laterally on
Flower can be divided into two similar
halves only in one particular vertical
plane.
acropetal succession.
E.g., Jasmine.
39. Region of maturation
29. (a) Solanaceae
Function: Root hairs absorb water and
(b) Epipetalous
minerals.
30. (a) Valvate [A] , Twisted [B]
(b) A - No overlapping of margins.
B - Margins overlap
31.
(a) Axile placentation (b) Parietal plac-
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CHAPTER - 6
ANATOMY OF FLOWERING PLANTS
Plant Anatomy is the branch of Biology
which deals with the study of tissues and
internal structure of plants.
Cells are the basic structural units of a
plant. Cells organized into tissues and tissues
into organs.
I. Simple tissues
They are made up of one type of cells. They
are with common origin and a common function . They are classified into Parenchyma,
Collenchyma and Sclerenchyma.
(i) Parenchyma
•
Isodiametric in shape.
•
They may be spherical oval, round polygonal or elongated in shape.
•
Cell wall thin—made up of cellulose
•
Either closely packed or with small inter
Complex Tissues
•
Complex tissue is composed of more
than one type of cells working together
as a unit for a common function.
•
cellular spaces.
They are two types (1) xylem and (ii)
phloem
Functions:
•
II.
1. Xylem
Photosynthesis, storage, secretion
Xylem functions as the conducting tissue for
water and minerals. It also provides mechanical support. It consists of following 4 types of
cells.
(i) Tracheids (ii) Vessels (iii) Xylem fibers
(iv) Xylem Parenchyma
(i) Tracheids
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They are elongated dead cells with tapering
•
ends and lignified cell wall.
is called xylem parenchyma.
Functions: Conduction of water, Mechanical support.
(ii) Vessels (Trachea)
•
The parenchyma associated with xylem
•
The cells are living and thin walled.
•
Their walls are made up of cellulose.
In angiosperms, the secondary xylem contains
They are long, cylindrical tube like struc-
radially elongated parenchyma cells called the
tures made up of many dead cells called
ray parenchyma. It helps in radial conduc-
Vessel members.
tion of water.
•
The vessel cell are devoid of protoplasm.
•
The vessel members are with lignified
Functions:
wall and large central cavity. The ves-
(1) Helps in upward conduction of water.
sel
(ii) Stores food materials in the form of
members
are
interconnected
through perforations in their common
wall. The wall area bearing perforation is called perforation plate.
•
Presence of vessels is a characteristic
feature of angiosperms.
•
starch or fat.
Protoxylem and metaxylem
The primary xylem is of two types.
(i) Protoxylem and (iii) Metaxylem
Gymnosperms lack vessels.
Functions of vessels: Upward conduction of
water , Mechanical Support.
(iii)
Xylem fibres (wood fibres):
•
They are sclerenchyma cells associated
with xylem.
•
•
They are thick walled , dead, elongated
cells with pointed ends.
Endarch and Exarch xylem
The walls are lignified with reduced lu-
Endarch xylem: Protoxylem lies towards the
men.
centre (pith) and metaxylem towards the periphery. Eg: Stem
Function: Mechanical Support.
(v) Xylem parenchyma (wood parenchyma):
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Exarch xylem: Protoxylem lies towards the
periphery and metaxylem towards the cen-
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tre Eg: Roots
III.
Epidermis is usually single layered.
2
IV.
The epidermis of root is called piliferous layer or epiblema.
V.
The outside of the epidermis is covered
with a waxy thick layer called cuticle.
Cuticle is absent in roots.
Stomata
I.
Stomata are minute pores presents in
the leaf epidermis.
II.
TISSUE SYSTEMS
shaped cells called guard cells.
A Group of tissues performing a similar function is called a tissue system. On the basis of
III.
IV.
tissue systems.
Epidermal tissue system.
2.
Ground or fundamental tissue system
V.
3.
Vascular or conducting tissue system.
1.
Epidermal tissue system (dermal tissue
system)
In dicots the guard cell are bean
shaped.
and
VI.
In monocots guard cell are dumb –bell
shaped.
VII. Epidermal cells associated with guard
cell
body. It is composed of epidermis, stomata
and epidermal appendages.
are
called
subsidiary
cells
(accessory cells).
It forms the outer most covering of the plant
VIII. Stomatal aperture, guard cells and subsidiary cells are together called stomatal apparatus or stomatal complex.
Epidermis
It is the outermost layer of the primary
plant body.
It is formed of elongated, compactly arranged living parenchyma cells.
Guard cells bear Chloroplasts and regulate the opening and closing of stomata.
1.
II.
Outer wall of guard cell is thin and inner
wall is thick.
structure and location, there are three types of
I.
Each stoma is guarded by two bean
Functions of Stomata
•
Transpiration
•
Gaseous exchange
Epidermal appendages
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They are of two types
•
both xylem and phloem are called con-
Root hairs: Epidermal hairs on the root are
joint vascular bundle.
called root hairs. They are unicellular elongation of the epidermal cell. They help to ab-
The vascular bundle which consists of
•
Xylem and phloem occur in the same
radius.
sorb water and minerals from the soil.
Trichomes: Epidermal hairs on the stem are
Collateral bundles: When xylem and phlo-
called trichomes.
em are placed side by side in the same bun-
They are multicellular,
branched, unbranched, or secretory.
dle it is known as collateral.
Function:
•
They help in preventing water
phloem facing outside.
loss due to transpiration.
•
Ground Tissue System.
•
•
Collateral bundle may be open or closed.
Tissues, excepct epidermis and vascular
Open vascular bundle: Vascular bundle with
bundles constitute the ground tissue.
Cambium in between xylem and phloem in a
Consists of parenchyma, Collenchyma
vascular bundle, it is called closed.
E.g: monocot stems.
and sclerenchyma.
•
In such a bundle xylem is internal and
In leaves, ground tissue is composed of
thin walled chlorenchyma cells called
Concentric bundle: Here one of the vascular
mesophyll.
component is central in position, while the other surrounds it.
The vascular tissue system
It consists of a number of vascular bundles.
Radial Vascular bundle
Each vascular bundle is made up of xylem and
In these bundles xylem and phloem groups oc-
phloem.
cur in the form of separate bundle (xylem
Function: Conduction of food and water.
bundles and phloem bundles).
These two bundle are found in different radii.
Vascular Bundles
E.g.: roots
Vascular bundle is formed of xylem and phloem.
There are two types of vascular bundle. (1)
Conjoint (2) Radial
Conjoint
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parenchyma cells with intercellular spaces.
Endodermis
•
The innermost layer of cortex is called
the endodermis.
•
It is composed of a single layer of compactly arranged barrel - shaped living
cells.
•
The radial walls and inner tangential
walls of endodermal cells are thickened
due to the disposition of water impermeable, waxy material called suberin.
•
ANATOMY
OF
DICOTYLEDONOUS
AND MONOCOTYLEDONOUS PLANTS
1. DICOTYLEDONOUS ROOT (DICOT
ROOT)
These thickenings are called the casparian strips (casparian thickenings)
Passage cells
Some cells of endodermis, especially those opposite to proxylem remain thin walled . Such
A thin transverse section (T.S. or C.S) of
cells are called passage cells. The passage cells
young dicot root show three distinct regions:
allow the passage of water from cortical cells
to xylem.
1.
Epidermis
2.
Cortex
3. Stele
3.
Stele
The central portion of the root is called stele.
It consists of pericycle, Vascular bundles,
1. Epidermis
Conjunctive tissue and Pith.
•
It is the outermost layer.
Pericycle: A few layers of thick walled par-
•
It bears unicellular root hairs.
enchymatous cells lie inner to the endo-
•
Stomata and cuticle are absent.
dermis.
Lateral roots originates from pericycle.
2. Cortex
•
Vascular cambium originates from pericy-
It consists of several layers of thin walled
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cle.
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Vascular bundles: They are
intercellular spaces.
•
Radial
Endodermis: It is the innermost layer of cor-
•
Bundles two to four in number.
•
Xylem is exarch.
•
Xylem vessels are polygonal in shape.
tex.
Cells are barrel shaped with casparian
strips. Passage cells present.
3. Stele
Conjunctive tissue:
It consists of parenchymatous cells found between xylem and phloem.
The stele consists of pericycle, vascular bundle, Conjunctive tissue and pith.
(i) Pericycle - single layer, parenchymatous
Pith:
(ii) Vascular bundles
It is small or inconspicuous.
•
Radial
•
Xylem is exarch
•
More than six bundles (polyarchy)
•
Xylem vessels are round in shape
(iii) Conjunctive tissue -
Parenchymatous
cells found between xylem and phloem
(iv) Pith - Large and parenchymatous
Secondary growth is absent in monocot root
Difference between dicot root and
monocot root
2.
Monocotyledonous root (monocot
root)
1. Epidermis
Composed of single layer of cells without cuticle. Root hairs present.
2. Cortex
Consists of parenchymatous cells with large
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DICOT ROOT
3. DICOTYLEDONOUS STEM
(Dicot Stem)
MONOCOT
ROOT
1. Xylem and phlo- 1. Xylem and phloem groups are lim- em groups are nuited in number (2 merous in number
A transverse section (T.S) of young dicot stem
shows 3 distinct regions - Epidermis, cortex
and stele.
to 6 ) diarch to hex- (polyarchy).
Epidermis
arch
•
The outermost protective layer of the di-
2. Xylem cells are 2. Xylem cells are
cot stem is called epidermis. It consists
polygonal in shape. rounded in shape.
of a single layer of cells.
3. Pith is reduced 3. pith is large and
•
It bears cuticle, trichomes and a few
stomata.
or absent.
well developed .
4.Secondary
4.Secondary
Cortex
growth is present
growth is absent.
It is the region between epidermis and stele. It
is differentiated into following three zones.
(i) Hypodermis
It consists of a few layers of Collenchyma below the epidermis. It provides mechanical support.
(ii) General cortex
Consists of round, thin walled, parenchyma
cells with intercellular spaces.
(iii) Endodermis
It is the innermost layer of cortex. The cells
are with starch grains.
Stele
It is the central part of the stem inner to the
endodermis. It consists of Pericycle, vascular bundles, medullary rays and pith,
(1)
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Pericycle: It is multilayered and scleren-
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chymatous.
It is found as semilunar
patches inner to endodermis and above
the phloem and forms a bundle cap
(2)
Vascular bundles:
It is composed of
xylem, phloem and cambium. Vascular
bundles possess following characters.
•
Limited in number
•
Arranged in a ring
•
Conjoint—xylem and phloem in the
same bundle
•
Collateral - Xylem and phloem in the
same radius
•
4. MONOCOTYLEDONOUS STEM
and phloem.
•
Endarch xylem -
A transverse section (T.S) of monocot stem
protoxylem lies to-
wards the Centre
•
(Monocot Stem)
Open - cambium present between xylem
shows the following parts epidermis, ground
tissue, and vascular bundles.
1. Epidermis
Xylem vessels are polygonal
Single layer of parenchyma cells. Cuticle and
(3) Medullary rays (pith rays)
stomata are present. Hairs are absent.
The radially elongated parenchyma cells present between two adjacent vascular bundles
2. Ground tissue
radiating from the pith is called a medullary
It is the mass of cells inside the epidermis ex-
rays.
cept vascular bundles.
(4) Pith (Medulla)
It is not differentiated. It is made up of paren-
The central part of the stele is known as pith.
chyma with intercellular spaces.
It is very large and made up of parenchyma
The region just below the epidermis is called
with
hypodermis. It is made up of sclerenchyma.
intercellular
spaces.
3.
Vascular bundles
It is composed of xylem and phloem. Vascular
bundles possess following characteristics.
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•
They are numerous and scattered in the
ground tissue
•
They are smaller and more numerous
towards the outside. They are larger and
more spaced towards the centre
•
Rounded or oval in shape
•
Conjoint and collateral .
•
Closed (Cambium absent between xylem and phloem)
•
Surrounded by sheath of sclerenchyma
known as bundle sheath.
•
Xylem is endarch (protoxylem points
towards the Centre)
•
Xylem Vessels are oval or round in
shape.
•
Phloem parenchyma is absent.
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Difference between dicot and monocot
leaf) shows 3 distinct regions.—Epidermis,
stem
mesophyll
Dicot stem
Monocot stem
1. Ground tissue is
1. Undifferentiat-
differentiated
ed
into cortex, en-
tissue.
dodermis, pericycle, stele and
pith.
2. Vascular bundles
are limited in
number and are
arranged in a
ring .
3. Vascular bundles
are open
4. Collenchymatous
hypodermis
5. Sclerenchymatous bundle cap
is present
6. Bundle sheath is
absent.
7. Protoxylem lacuna is absent.
8. Secondary
growth is pre-
vascular
bundles.
ground
2. Vascular bun-
dles are numerous and scat-
1. Epidermis
•
Upper and lower epidermis are covered
with cuticle.
tered.
3. Vascular bun-
•
mis (adaxial epidermis)
4. Sclerenchymatous hypodermis.
The lower epidermis (abaxial epidermis)
bears more stomata than upper epider-
dles are closed.
2. Mesophyll
The tissue between the upper and lower epider-
5. Bundle cap is
mis is called mesophyll. The cells carry chloroplast.
absent.
6. Sclerenchyma-
•
Mesophyll is differentiated in to upper
tous bundle
palisade parenchyma and lower spongy
sheath is pre-
parenchyma.
sent .
(1)
Palisade parenchyma - They are adaxially placed, made up of elongated cells,
7. Protoxylem
lacuna is pre-
arranged vertically and parallel to
sent.
each other.
(i) Spongy parenchyma - Oval or round
8. Secondary
growth is ab-
loosely arranged cells with large intercellu-
sent.
lar spaces.
sent.
These cells lie towards the lower epidermis.
1. DICOT OF LEAF (Dorsiventral leaf)
3.
A cross section of a dorsiventral leaf (dicot
•
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and
Vascular bundles
They are found in veins and midrib
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They are surrounded by a layer of paren-
•
Each bundle is covered by parenchyma-
•
chymatous bundle sheath.
tous bundle sheath.
Vascular bundles are Collateral and
•
closed.
These are large empty colorless cells
•
Xylem on the upper side and phloem on
•
the lower side.
•
2.
Bulliform cells (Motor cells)
found in the adaxial epidermis in grasses.
When the bulliform cells in the leaves
•
The protoxylem is turned to the upper
have absorbed water, they are turgid. As
epidermis.
a result, leaf surface is exposed.
MONOCOT LEAF (Isobilateral leaf)
Due to the water stress bulliform cells
•
become flaccid. As a result, they make
A cross section of monocot leaf shows three
the leaves curl inwards to minimize the
regions epidermis, mesophyll and vascular
water loss.
bundle.
Difference between dorsiventral leaf
(dicot leaf) and isobilateral leaf (monocot
leaf)
Dorsiventral
leaf Isobilateral
(dicot leaf)
leaf
(monocot leaf)
1. Cuticle thick at 1.
Uniform cuticle
upper epidermis on both surface.
Epidermis - Upper and lower epidermis are
coated with cuticle . Stomata are present on
both the epidermis. The upper epidermis. The
upper epidermis contains special bulliform
cells.
are 2. Equal number of
more on lower
stomata on either
surface.
side.
3. Mesophyll is dif- 3. Mesophyll is not
Mesophyll—It is not differentiated into palisade and spongy tissue.
ferentiated
palisade
into
paren-
chyma and spon-
Vascular bundles: They are collateral, closed
and endarch type.
•
2. Stomata
gy parenchyma.
4. Bulliform
Xylem occurs towards the upper side and
differentiated.
4. Bulliform
cells
are present in upper epidermis.
cells
are absent in the
phloem towards the lower side.
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IMPORTANT QUESTIONS
b) Veins from a network.
1.
Stem grows in girth due to ………
c) Mesophyll is well differentiated into
2.
Closed vascular bundles lack…….
3.
Outermost layer of stele is called ……
4.
Epiblema of roots is equivalent to
palisade and spongy parenchyma.
d) Mesophyll is not differentiated into
palisade and spongy parenchyma.
10.
a)
Pericycle
ing of the leaf surface?
b)
Endodermis
(a) Bulliform cells
c)
Epidermis
(c) Palisade parenchyma
d)
Stele
(d) Bundle sheath cells.
5. Complex tissues are found in higher plant
tissues, found in gymnosperms from the hints
provided below:
overcome water stress?
12. Choose the appropriate terms given below
and arrange them correctly in the table
Xylem tracheids, Xylem vessels, sieve
provided.
tubes, albuminous cells, sieve cells, com
Casparian strips, Starch sheath, poly
panion cells, xylem parenchyma.
archy xylem, closed vascular bundles,
Differentiate exarch and endarch arrange-
bundle sheath, bundle cap, spongy paren
ment of primary xylem.
7.
(b) Xylem tissue
11. How does bulliform cells help grasses to
groups, Choose the components of complex
6.
Which of the following helps in the curl-
chyma.
Epidermal hairs are found in root and
stem.
Monocot
stem
Dicot stem
Monocot
root
(a) Name the epidermal hairs in stem.
(b) Write any two functions of stem.
8.
9.
A conjoint and open vascular bundle will
13.
In the early morning, droplets of water
be observed in the transverse section of
can be found at the tips of grass leaves.
…...
Name the phenomenon. Can you give
an explanation for this phenomenon?
In a monocot leaf
a) Bulliform cells are absent from the
epidermis
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Anatomy of flowering plants
We rise by lifting others • 340 .
PREVIOUS YEARS QUESTIONS
and write the structures seen in epider
mal tissue system. Write their functions.
14. Choose the correct answer.
19. The following are the anatomical features
Casparian strips are present in
of flowering plants. Arrange these fea-
(a) Dicot root
(b) Dicot stem
tures in the table given below:
(c) Dicot leaf
(d) Monocot stem
i)
Exarch xylem
ii)
Presence of hypodermis
15. Observe figure given below:
iii) Palisade parenchyma cells
iv) Conjoint and open vascular bundles
v)
Endodermis with casparian strips
vi) Large empty bulliform cells
Write any three features on mesophyll
Stem
cells from the figure. .
Root
Leaf
16. Arrange the following anatomical characters in appropriate column.
Conjoint vascular bundle, Upper and
lower epidermis, Exarch xylem, Radial
vascular
bundles,
Endarch
20. Complete the flow chart given below:
xylem,
Ground tissue is called mesophyll.
17.
Some functions of various tissues in
plants are given below. Identify the tissue.
a)
Conduction of water
b)
Provides support
to the growing
parts of the plant
c)
18.
Storage
21. The tissue found between the upper and
Observe the terms given below:
lower epidermis of a leaf called meso-
Xylem, Root hairs, Pith, Stomata, Cam
bium, Bulliform cells. From this identify
Plus 1 Biology
phyll
(a) Write the type of cells found in this
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Helping others is the way we help ourself • 341 .
tissue in a dicot leaf.
and replace the outer broken cortical and
epidermal layers?
(b) Mention two differences between a
dicot leaf and monocot leaf.
26. The internal anatomy of dicot and monocot stems shows many differences. Men-
22. Choose the correct answer?
tion any four differences between their
All tissues on the inner side of the endo
vascular bundles.
dermis together constitute.
a) Conjunctive tissue
c) Pericycle
b) Stele
d) Vascular bundle
ANSWERS
1.
Vascular cambium ,lateral meristem
below:
2.
Cambium
Identify the plant part and explain any
3.
Pericycle
two features of its vascular bundles.
4.
Epidermis
5.
Xylem tracheids, albuminous cells, sieve
23. Observe the T.S. of a plant part given
cells, xylem parenchyma.
6.
Endarch xylem - Protoxylem lies towards
pith and protoxylem towards periphery.
Exarch xylem - Metaxylem lies towards
pith and protoxylem towards periphery.
7.
b) Secretory, prevent water loss due to
24. The following are the characters of and
monocot stems.
a) Trichomes
transpiration.
Identify the characters
and write in appropriate column:
8.
Dicot stem.
a) Sclerenchymatous hypodermis
9.
Mesophyll is not differentiated into palisade and spongy parenchyma.
b) Collenchymatous hypodermis
c) Vascular bundles are conjoint, closed
d) Vascular bundles are arranged in a
ring.
10.
Bulliform cells
11.
Bulliform cells absorb water and become
turgid and the leaf surface exposed.
When they become flaccid due to water
25. How does periderm develop in dicot stem
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If you can dream it, you can do it • 342 .
stress, leaves curl inwards and minimize
water loss.
12.
17.
a)
Xylem
b)
Collenchyma
Parenchyma
Monocot
stem
Dicot stem
Monocot
root
c)
Closed vascular bundles, bundle
sheath
Starch
sheath, bundle cap
Polyarch xylem, casparian strips.
18.
Root hair - Absorption of water and
minerals.
Stomata
-
Transpiration and gaseous
exchange.
Bulliform cells - Rolling and unrolling
13. Guttation
of leaves to reduce surface area; when
It is the loss of water in the form of drop
turgid they expose leaf surface and when
lets from the vein ending of the leaf.
flaccid curls.
19.
14. a) Dicot root
15. 1) Divided into palisade and spongy pa-
renchyma.
2) Spongy parenchyma loosely packed
with air cavities.
3) Palisade parenchyma contains more
chloroplast.
Stem
Root
Leaf
Conjoint and Exarch xyopen vascu- lem
lar bundles
Presence of
hypodermis
Palisade parenchyma
cells.
Endodermis Large empty
with caspari- bulliform
an strips.
cells
16.
Stem
Root
1. Con- 1. Exarch
joint vas- xylem
cular
2. Endarch xylem
20.
Leaf
1. Upper and
lower epidermis
2. Radial
2. Ground
vascular bun- tissue is
dles
called meso-
.
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The enlightened minds can't be dark • 343 .
21. (a) Palisade parenchyma and spongy parenchyma.
25.
•
(b)
Monocot Leaf
1. Isobilateral
tissue cork cambium or
phellogen develops in the cortex.
Dicot Leaf
1. Dorsiventral
2. Stomata equally 2. Stomata usually
present on both sur- present on lower
faces
surface.
3. Stomata have
dumbbell shaped
Meristematic
•
Phellogen cuts off cells on both sides.
•
The outer cells differentiate into suberized cork or phellem.
•
chymatous secondary cortex or phello-
3. Stomata have
bean shaped guard
derm.
•
4. Mesophyll is un- 4. Mesophyll is difdifferentiated
ferentiated into palisade and spongy
The inner cells differentiated into paren-
Phellogen, phellem and phelloderm are
collectively known as periderm.
•
At certain region, the phellogen cuts off
closely arranged parenchymatous cells
5. Bulliform cells
are present.
22.
(b) Stele
23.
Dicot stem
5. Bulliform cells
are absent.
called lenticels.
26.
Dicot stem
Vascular bundles are arranged in the
form of ring.
Vascular bundles open, conjoint.
Endarch xylem
24.
Dicot stem
Monocot stem
1. Collenchymatous hypodermis.
1. Sclerenchymatous hypodermis.
2. Vascular bundles.
2. Vascular bundles
ar conjoint, closed.
Plus 1 Biology
on outer side with lens shaped opening
Monocot stem
1. Ground tissue 1. Ground tissue
is differentiated
is not diffentiated.
into cortex, endodermis, pericycle
and pith.
2. Vascular bundles are arranged
in a ring.
2. Vascular bundles are scattered.
3. Vascular bundles are open
without bundle.
3. Vascular bundles are closed
surrounded by
sclerenchymatous
bundle sheath.
4. Secondary
growth present.
4. Secondary
growth absent.
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Anatomy of flowering plants
Knowledge is the new currency • 344 .
CHAPTER - 7
STRUCTURAL ORGANISATION IN ANIMALS
FROG
active state till favourable conditions
return.
Morphology

Skin is moist, smooth and slippery due to
the presence of mucus.

Dorsal side of the body is olive green
with dark, irregular spots.


colour.
The most common species of frog found
in India is Rana tigrina. They are am-

phibious i.e. they can live both on land



in water.
so they do not have a constant body temperature.

A membranous tympanum is present on
either side of the eyes to receive sound
They show the phenomenon of camou-
signals.
flage, i.e., they have the ability to
change the colour of their skin to sit the
Bulging eyes are protected by a nictitating membrane that protects them while
with the temperature of the environment,

A pair of nostrils is present above the
mouth.
They are poikilothermic or Cold blooded, i.e. their body temperature varies

Body is divisible into head and trunk.
Neck and tail are absent.
and in freshwater. They belong to class
Amphibia of phylum Chordata.
Ventral side of the body is pale yellow in

Fore limbs and hind limbs are used for
colour of the surroundings.
swimming, walking, jumping, leaping
They exhibit aestivation or summer
and burrowing.
sleep during peak summer and hiberna-

Hind limbs end in five digits and they are
tion or winter sleep during peak winter.
larger and muscular than fore limbs
During this period they take shelter in
which end in four digits.
deep burrows to protect them from extreme heat and cold and remain in an inPlus I Biology

Feet have webbed digits that help in
swimming.
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
Frogs exhibit sexual dimorphism.

Males

into the stomach which in turn continues
have sound producing vocal
as the intestine, rectum and finally opens
sacs and also copulatory pads on the
outside by the cloaca.
first digit of the fore limbs which are absent in females.



Pancreas, a digestive gland produces
pancreatic juice
Anatomy

Liver secretes bile that is stored in the
gall bladder.
Frogs absorb water through the skin;
they never drink water.
Oesophagus is a short tube that opens
containing digestive
enzymes.
The body cavity of frogs accommodate
different organ systems like, digestive,

Food is captured by the bilobed tongue.
circulatory, respiratory, nervous, excreto-
Digestion and absorption
ry and reproductive systems with well

Digestion
of food takes place by the
developed structures and functions.
action of HCI and gastric juices secret-
1.
Digestive system
ed from the walls of the stomach.

Consists of alimentary canal and diges-

passed from stomach to the first part of
tive glands.

the intestine, the duodenum.
Alimentary canal is short because frog
are carnivores; so length of the intestine

Duodenum receives bile from gall bladder and pancreatic juice from the pan-
is reduced.

Partially digested food called chyme, is
creas through a common bile duct.
Mouth opens into the buccal cavity that
leads to the esophagus through Pharynx.

Bile emulsifies fat and pancreatic juices
digest carbohydrates and proteins.

Final digestion takes place in the intestine.

Diested food is absorbed by the numerous finger—like folds in the inner wall
of intestine called villi and microvilli.

The undigested solid waste moves into
the rectum and passes out through cloaca.
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2.
Respiratory system

Frogs respire on land and in the water by
•
two different methods, in water, skin acts
brane called pericardium.
•
as aquatic respiratory organ (cutaneous
respiration). Dissolved oxygen in the
water is exchanged through the skin by
•

On land, the buccal cavity, skin and lings
Respiration by lings is called pulmo-
nus arteriosus on the ventral side of the
•
Comprises of arteries and veins.
Arteries: They carry oxygenated blood from
of elongated, pink coloured sac - like
heart to all parts of the body (arterial system).
structures present in the upper part of the
Veins: They collect deoxygenated blood from
trunk region (thorax).
different parts of the body to the heart (Venous
Air enters through the nostrils into the
system).
During aestivation and hibernation, gas
exchange takes place through skin.
3.
Blood vessels
nary respiration. The lungs are a pair
buccal cavity and then to lungs.

The ventricles opens into a sac—like Coheart.
act as respiratory organs.

A triangular structure known as sinus
venosus joins the right atrium.
diffusion.

It is covered by a double layered mem-
Circulatory system
Circulatory system consists of (A) Blood vascular system
Portal system: This system consists of
veins and their capillaries that collect deoxygenated blood from a major organ and
empty it into some other organ through
capillaries, instead of pouring its contents
into the right auricle through a larger vein.
This system begins and ends in capillaries
in the liver or kidney.
(A)
Blood vascular system
Hepatic portal system:
•
It is of the closed type
harmful nitrogenous wastes are purified and
•
Consists of heart, blood vessels and
glucose gets converted to glycogen.
blood.
Renal portal system: This system collects
blood from the intestine to the liver. Where
blood from the lower parts of the body and
Heart
•
Heart is muscular structure situated in
the upper part of the body cavity.
•
this system carries
kidney. Blood reaches the heart through the
kidneys where urea and uric acid present in
blood are filtered.
It is three chambered, with two auricles
(atria) and one ventricle.
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Blood
•
orly in the body cavity on either side of
puscles.
RBC (Red Blood cells) or
or leucocytes and platelets or thrombo-
niferous tubules or nephorns.

the kidneys. The ureters act as urino-
coloured respiratory pigment haemoglo-
genital ducts which open into the cloaca.

Blood transports nutrients, gases, water
circulation.
open separately in the cloaca.

The muscular heart (myogenic )pumps

Consists of lymph, lymph channels and

excreted.
It is filtered out from the blood capillar5.
It is different from blood. It lacks a few
proteins and RBCs.
Control and coordination
The system for control and coordination
is well—developed in frog and involves both
nervous system and endocrine system.
4.
Excretory system

Frog has a well—developed excretory
system to eliminate nitrogenous wastes
from the body.
Neural system

Neural system in frog is highly evolved
and organized into a central nervous
The excretory system consists of a pair
of kidneys, ureters, cloacea and urinarybladder.

Excretory wastes are carried by blood
into the kidney where it is separated and
ies in the form of a colorless fluid.

Nitrogenous waste is excreted in the
form of urea, so frog is ureotelic.
lymph nodes.
•
A thin walled urinary bladder is present
into the cloaca.
(B) Lymphatic system
•
In female frogs, the ureters and oviduct
ventral to the rectum which also opens
blood to the different parts of the body.
•
In male frogs, two ureters emerge from
RBC’s are nucleated and contain the red
and wastes to the respective sites during
•
Each kidney is composed of several
structural and functional units called uri-
bin.
•

erythrocytes, WBC (White Blood Cell)
cytes form the blood cells.
•
the vertebral column.
Composed of plasma and cells or cor-
system (brain and spinal cord), a peripheral nervous system (cranial and
spinal nerves) and an autonomous nervous system (sympathetic and parasympa-
Kidneys are compact, dark red, bean
thetic. )
shaped structures situated a little posteriPlus I Biology
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
There are 10 pairs of cranial nerves
(nerves arising from the brain).


6. Endocrine system

Brain is enclosed within the cranium of
organs of the body is carried out by hor-
the skull. It is divided into fore—brain,
mones secreted by the endocrine glands
mid –brain and hind—brain.
(ductless glands).
Fore - brain is represented by a pair of

rold, thymus, pineal body, pancreatic
Hind - brain consists of cerebellum
islets, adrenals and gonads.
and medulla oblongata, which extends
into the spinal cord enclosed within the

Endocrine glands are ductless glands and
vertebral column; after passing out
their secretions are called hormones;
through the foramen magnum.
which are released directly into the blood
stream.
Sense organs

The prominent endocrine glands found in
frog are pitultary, thyroid, parathy-
optic lobes.

The chemical coordination of various
Frog has all 5 types of sense organs.
7.
Reproductive system
Sexes are separate in frog. They have
They are the following.
well organized male and female reproductive

Organs of touch - Sensory papillae

Organs of taste - taste buds.

Organs of smell - nasal epithelium

Organs of vision - eyes
sist of a pair of ovoid, yellowish testes,

Organs of hearing - tympanum with
which are found attached to the upper
systems. They show sexual dimorphism.
Male reproductive system

Male reproductive organs: They con-
part of kidneys by a double fold of peri-
internal ear
toneum called mesorchium.

Eyes (simple eyes) are a pair of spherical structures situated in the orbit in the

Vasa efferentia arising from testes are
10 - 12 in number, they enter the kidneys
skull.
on their side and open into Bidder’s ca
External ear is absent. Only the tympa-
nal.
num is visible externally.


Finally it communicates with urinogeni-
Ear is an organ of hearing and equlibri-
tal duct that comes out of the kidneys
uim (balancing).
and opens into the cloaca.

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Cloaca is a small, median chamber that is
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Whatever you are, be a good one • 349 .
used to pass faecal matter, urine
and
sperms to the outside.
Female reproductive system

This includes a pair of ovaries. They
are situated near the kidneys but there is
no functional connection with them.

A pair of oviducts arise from the ovaries
and open into the cloaca separately.

A mature female lays 2500 - 3000 ova at
a time.
Fertilization and development

Fertilization is external and takes place
in water.

Development is indirect and involves a
larval stage called tadpole.

Tadpole undergoes metamorphosis to
form the adult.
Economic Importance

Frogs are harmless and beneficial to
mankind.

They eat insects and thus protect crops.

Frogs serve as an important link in the
food chain and food web, so they help
to maintain ecological balance
in the
ecosystem.

IMPORTANT QUESTIONS
1. Frog show sexual dimorphism.
a) Write the morphological differences
present only in male frogs.
The muscular legs of frogs are used as
food by man in some countries.
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Nothing can dim the light that shines within you • 350 .
2. a) Identify the diagram .
5. In frog, the toes are inter—connected by
skin.
b) Label the numbered parts.
a) What is it called ?
b) What is its function ?
6.A frog with body temperature 23.50 C is
transferred to an area having 25 0 C temperature. What will be the body temperature of
this frog in the new environment ? Substantiate your answer.
7. Complete the table.
Animal
Excretory
Respiratory
organ
Organ
…….
………
Frog
3. Differentiate aestivation from hibernation?
4. Name the labelled parts a, b, c and d in the
diagram given below.
8. Mention the function of the following.
1. Ureters in frog.
9. Regarding the blood - vascular system of
frog, some statements are given below.
Check whether these are true or false and
make corrections if necessary.
a) Open type
b) Sinus venosus joins the right ventricle
c) RBC is non– nucleated
d) Circulation is achieved by the pumping
action of the heart.
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ANSWERS
8. 1. Passage of urine (urea) and sperms
1. a) 1. Presence of vocal sacs 2. Presence
of copulatory pad on the 1 st digit of
9. a) False
b) False
- Closed type
- Sinus venosus joins the
right atrium
the forelimb.
2. a) Male reproduction system and excretory
system of frog. b) 1 - Fat body
c) False
- Nucleated
d) True
2 - Testis , 3 - Kidney , 4 - Rectum ,
5 - Urinary bladder.
3. Aestivation
- summer sleep
Hibernation - winter sleep
4.
a - Liver, b - Pancreas, c - Rectum,
d - Urinary bladder
5.
a) Web
b) It helps in swimming
6.
The body temperature of frog in the new
environment will be 250C. Because ,
frogs do not have constant body temperature. So , they are poikilotherms ( cold blooded animals) with their body temperature changing with surrounding temperature changes.
7.
Animal
Frog
Plus I Biology
Excretory
Respiratory
organ
organ
Kidney
Lungs and
skin
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Hard work beats talent when talent doesn't work • 352 .
CHAPTER 8
CELL:THE UNIT OF LIFE
What is a cell?
The cell is the basic structural and functional
unit of life.
Cell theory
i. The cell theory was formulated first by two
biologists, M.J. Schleiden and Theodore
Schwann.
ii. They proposed the hypothesis that the bodies of animals and plants are composed of cells
and products of cells.
prokaryotic cells lacking a membrane- bound
nucleus and organelles.
CYTOPLASM
Is the semifluid matrix of the cell which is the
main area of cellular activities that keep the
cell in the living state.
Membrane bounded cell organelles are:
ENDOPLASMIC RETICULUM (ER): It
consists of an intercommunicating system of
channels made of membranous sacs
iii. Rudolf Virchow first explained that cells
divide and new cells are formed from preexisting cells.
AN OVERVIEW OF CELL
CELL WALL
•
It is the outer boundary of plant cell. Cell
membrane is present inside it.
• Cell membrane is the outer boundary of
animal cell.
NUCLEUS
• The principal organelle of the cell.
• It is a membrane bound structure that contains chromosomes which in turn contains
the genetic material DNA.
a) Rough ER (RER): It bears ribosomes on its
membrane surface. It is involved in protein
synthesis and secretion.
b) Smooth ER (SER): It is free from ribosome
and synthesis lipids
EUKARYOTE
GOLGI COMPLEX
Eukaryotes are distinguished by the fact that
their cells possess a membrane – bound nucleus containing the genetic material.
• Consists of stacks of flat, membranous cisternae.
Eg. Amoeba, Angiosperms.
• It helps to concentrate secretory materials
and packs them into secretory vesicles
PROKARYOTE
An organism that is either a bacterium or a
blue- green algae, its main characteristic being
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A Cavity in the cytoplasm containing an aqueous solution and bound by a unit membrane.
Non – membrane-bound organelles are:
RIBOSOMES

These are granular organelles and are not
enclosed by any membrane.

Found in both Eukaryotic and prokaryotic.

Within the cell, ribosomes are found not
only in the cytoplasm, but also within the
two organelles – chloroplasts (in plants)
and mitochondria and on rough ER.
LYSOSOMES
• They are termed the ‘suicidal bags’ of the
cell.
• They store acid hydrolases in their fluid content.
• They fuse with damaged organelles and hydrolyse them.
CENTRIOLE

Animal cells contain another nonmembrane bound organelle called centriole which helps in cell division.

Cells differ greatly in size, shape and activities.
PROKARYOTIC CELLS
• They are primitive. They do not contain a
true nucleus and membrane-bound cell organelles.
• They have a cell wall, surrounding the cell
membrane.
MITOCHONDRIA
• No well-defined nucleus.
The power house of a cell.
• In addition to genomic DNA, many bacteria
have smaller circular DNA called plasmid,
are present.
• Specialized form of cell membrane called
mesosomes are present.
• Ribosomes and other inclusions are scattered in the cytoplasm
MICROBODIES
• Prokaryotic cells are represented by bacteria
and blue-green algae, mycoplasma and
PPLO (pleuro pneumonia like organisms.)
Many membrane- bound minute vesicles.
There are four basic shapes of bacteria:-
VACUOLES
*
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Bacillus
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
Coccus

Vibrio
MESOSOMES
Spirillum
• A Special membranous structure which is
formed by the extensions of the plasma
membrane into the cell in bacteria are
called mesosome.

into and out of the cell.
PLASMID



A Circular piece of DNA found in the cytoplasm of bacterial cells that replicates independently of the host chromosome.
The plasmids can be important in public
health since some types possess genes for
antibiotic resistance, and can be quickly
transferred to different types of host cells,
thus spreading resistance very rapidly.
Plasmids are used extensively in genetic
engineering of microorganisms.
CELL ENVELOPE AND ITS MODIFICATIONS

It is the outermost layer.

Some have a loose sheath around the outermost layer, known as slime layer. This
slime layer protects the cells from loss of
water and nutrients.
Sometimes in some others, this layer is covered with a thick and tough covering. This
is known as capsule.
This capsule is essential for the survival of the
cell.
CELL WALL

It is seen below the glycocalyx.
This layer is rigid due to the presence of peptidoglycan.
PLASMA MEMBRANE
• It is the innermost layer of the cell envelope.
• It is semipermeable in nature.
• It controls the flow of specific molecules
Plus I Biology
• They also help in respiration, secretion processes and increase surface area of plasma
membrane and enzyme action.
• In some prokaryotes like cyanobacteria
there are certain membranous extensions
into the cytoplasm called chromophores.
• Flagella: filamentous extensions from the
cell wall which help in locomotion (eg:
bacteria.)
GLYCOCALYX

• These are in the form of vesicles, tubules
and lamellae that help cell wall formation,
DNA replication and distribution into
daughter cells.
• Bacterial flagellum is composed of three
parts – filament, hook, and basal body.
• Pili elongated tubular structures from the
surface of bacterium.
• Fimbriae: There are small bristle like fibres
sprouting out of the cell in bacteria.
GRAM STAINING
• Gram staining is a special technique which
is used to classify bacteria.
• This technique was developed by Christian
Gram in 1884.
Procedure
• Firstly, bacteria are treated with weak alkaline solution of crystal violet or gentian violet.
• The stained bacteria are again treated with
0.5% iodine solution.
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• This is followed by washing with water and
alcohol or acetone.
• Extensive compartmentalization of cytoplasm
• After these procedures, some bacteria retain
the purple color, while some others lose it
and are colorless.
• Presence of membrane-bound organelles.
• Those having purple color are known as
Gram positive bacteria and those that do not
have color are known as gram negative bacteria.
•
Presence of organized nucleus with a nuclear envelope
Plant cell
RIBOSOMES AND INCLUSION BODIES
RIBOSOMES
• Ribosomes are the sites of protein synthesis.
• In prokaryotes 70S ribosomes are present. It
is made up of 50S and 30S sub units.
POLYRIBOSOME OR POLYSOME:
Several ribosomes may attach to a single
mRNA and form a chain called polyribosomes
or polysome.
INCLUSION BODIES
Animal cell
STORAGE GRANULES

The reserve material seen in prokaryotic
cytoplasm is known as storage granule.

They are not bound by any membrane system and lie free in the cytoplasm.
Different types of storage granules
•
Phosphate granules
•
Cyanophycean granules
•
Glycogen granules
•
Gas vacuole
•
Volutin granules
•
Sulphur granules
EUKARYOTIC CELLS
Models of plasma membrane
• Eukaryotes include all the protists, plants,
animals and fungi
There are two models of plasma membrane.
They are
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i. Unit membrane model

The extrinsic proteins are arranged on the
surface and are loosely bound to the lipid

The intrinsic proteins are partially or totally
burried in the lipid bilayer.

This model of cell membrane is also called
'protein icebergs in a sea of lipids."
ii. Fluid mosaic model
Unit membrane model

Studies shows that the chemical composition of plasma membrane is variable with
lipids, proteins and oligosaccharides.

Lipid is the main component in it.
Cell wall

There are small globular proteins that lie
within the lipid bilayer
Do all cells have cell wall?
Fluid Mosaic model
• Only plant cells possess a cell wall.
• It provides fixed shape and size to the plant
cell.
• There is a pectin layer that attaches two adjacent plant cells. This layer is known as
middle lamella.
Structure of cell wall

This model was proposed by S.J. Singer
and G.L. Nicholson in 1972

There is a lipid bilayer intermingled with
proteins

This shows a kind of mosaic arrangement

The lipid bilayer is composed of phospholipids


Each phospholipid has a polar head and
two nonpolar tails.
The polar heads are hydrophilic (waterloving) and non-polar tails are hydrophobic
(water-hating).
The proteins are of two types; extrinsic and
intrinsic or integral.
Plus I Biology
The cell wall consists of three distinct layers.
They are,
(1)
Primary wall
(2)
Secondary wall
(3)
Middle lamella
1. Primary wall
• This layer consists of a network of micro
fibrils.
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• It is formed of cellulose, hemicellulose,
pectin and proteins. It is living and can
grow.
2. Secondary wall
•
It is made up of cellulose fibrils.
•
Sometimes hemicellulose, pectin and lignin are also deposited in it.
• The Golgi complex consists of a system of
mem brane-bound vesicles of varying sizes
arranged in parallel arrays.
• In most cells it consists of one or more
stacks of flat, expanded intercommunicating, cisternae.
• Cisterna is a fluid-filled lumen enclosed by
a single smooth membrane.
3. Middle lamella
•
Golgi apparatus
It is a cementing layer between adjacent
primary walls and is formed of calcium
and magnesium pectate.
• Small vesicles of varying sizes are found
associated with the cisternae.
• Cisternae are usually stacked in parallel
rows. They exist as an extensive network
near the nucleus.
Plasmodesmata
The cells are interconnected by cytoplasmic
bridges. These bridges are known as plasmodesmata. They help in maintaining continuity
of living matter, and the cytoplasm in such
condition is called symplasm.
The Endoplasmic reticulum (ER)
• It is a single membrane-bound cell organelle.
• It is involved in active secretion.
• The ER bearing ribosomes on their surface
is called rough endoplasmic reticulum
(RER).
• In the absence of ribosomes they appear
smooth and are called smooth endoplasmic
reticulum (SER).
Functions of ER
• Mechanical support
• Synthesis of secretory (serum proteins), lysosomal or membrane proteins on the ER
membrane and its transport through ER lumen.
• In plants, the stacks are also called dictyosomes.
Lysosomes
• Suicidal bag of the cell.
•
Bound by a single membrane.
•
Lysosome contains hydrolytic enzymes
(hydrolases).
•
They are formed by the budding off of vesicles from Golgi apparatus
•
It is concerned with intracellular digestion.
Vacuoles
•
They are fluid-filled sacs bound by a single
membrane.
•
The membrane is known as tonoplast. The
fluid in them is called cell sap.
Vacuoles can be classified into four types.
• Synthesis of lipids
• Detoxification of drugs
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Types of vacuole
Sap vacuole
Functions
Stores and concentrates mineral salts and
nutrients.
Contractile vacu- Takes part in osmoregole
ulation and excretion
present in animal cell.
Food vacuole
Helps in digestion
Air vacuole
Present in prokaryotes;
store metabolic gases;
helps in buoyancy of
• Inside the chloroplast, there is a colorless
substance called the stroma. It is the site of
dark phase reactions of photosynthesis.
• Stroma contains membrane systems consisting of closed, flattened sacs called
thylakoids.
• The thylakoids are kept one on top of the
other like pillar of coins to form structures
called grana. It is the site of light phase reactions of photosynthesis.
• Grana are connected together by a system of
membranes known as intergranal
thylakoids.
• Chloroplast contains chlorophyll.
Mitochondria
• Known as power house of the cell.
• Mitochondrion is a double membranebound cell organelle and are usually sausage
-shaped, spherical, oval, pear-shaped, cylindrical or filamentous.
• It has an outer smooth membrane and inner
membrane with many infoldings called cristae. Cristae increases surface area. It has
many spherical particles attached to it,
which acts as ATP synthase.
Plastid
• Plastids are organelles that are found only in
plant cells and in some unicellular organisms
like euglenoids.
Classification of plastids
Based on the contents, pigments and storage
materials, plastids are classified into three
• The thylakoids are the storehouses of pho
tosynthetic pigments and the enzymes for
the light reactions of photosynthesis.
Leucoplast
Chromoplast Chloroplast
• They are
colorless
plastids.
• They are
colored
plastids
• They are
green plastids containing the
• They are
• They conpigment
present in
tain fat solchlorolarge numuble carotphyll.
bers in the
enoid pigcells of
ments.
• They are
fruits, seeds,
This gives
found in
tubers and
the part of
the green
rhizomes.
the plant a
parts of the
yellow,
plant.
orange or
red color.
Structure of Chloroplast
• It consists of two membranes, the outer and
inner membranes.
• The two membranes are separated by a periplastidial space.
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• An elaborate network of filamentous proteinaceous structures present in the cytoplasm is called cyto-skeleton.
Functions of cytoskeleton
• Mechanical support
• Motility
• Maintenance of the shape of the cell.
RIBOSOME
• They are tiny organelles found in prokary
otes and eukaryotes
•They are the sites of protein synthesis.
• Each ribosome consists of two sub-units, one
large and one small.
Cilia and Flagella
• They are hair-like outgrowths of the cell
membrane.
• The organelle is made of 11 microtubules
(9+2) enclosed by cell membrane. Of these,
9 microtubules are doublets and peripheral
in position; 2 microtubules are single and
central.
Function:
Types of ribosomes - 70 S and 80 S
• The 70 S ribosomes are found in prokaryotes and 80 S ribosomes occur in the cytoplasm of eukaryotes.
Functions of ribosomes
) ER-bound ribosomes synthesize secretory
and lysosomal proteins.
) Free ribosomes synthesize non-secretory
proteins
Cytoskeleton
Plus I Biology
They help in locomotion, formation of food
and water current and elimination of solid particles.
Centrosome and Centrioles
• Centrosome is an organelle usually containing two cylindrical structures called centrioles.
• It is surrounded by amorphous pericentriolar materials.
• Triplet of microtubules.
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• The central part of the centriole is proteinaceous and called the hub.
Nucleus
•
Discovered by Robert Brown (1831).
•
This is a large organelle controlling all the
activities of the eukaryotic cells.
•
Nucleus is covered by two membranes
(outer and inner) which form a nuclear envelope.
•
The outer and inner membranes are separated by a narrow space called the perinuclear space.
•
Internal matrix is known as nucleoplasm.
• The nuclear envelope is interrupted by the
presence of small structures called pores.
The pores are enclosed by circular structures
called annuli.
Based on the position of the centromere, the
chromosomes can be classified into 4 types>
1.
Metacentric
• Nucleus contains chromatin reticulum which
transforms into chromosomes during cell
division.
2.
Sub-metacentric
3.
Acrocentric
4.
Telocentric
• Chromatin contains DNA and some basic
proteins called histones, and some nonhistone proteins and also RNA.
• Every Chromosome essentially has a primary constriction or the centromere on the sides
of which disc-shaped structures called kinetochores are present.
Functions.
Chromosomes contain DNA) DNA is organized into genes which control all the activities
of the cell (Nuclear division is the basis of cell
multiplication. The nucleolus manufactures
ribosomes.
Plus I Biology
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Nucleolus
(a) Name the scientists.
This is a spherical structure seen in the nucleus. The nucleolus is the site of ribosomal RNA
(rRNA) synthesis. The nucleoli are larger and
more numerous in cells that are actively involved in protein synthesis.
(b) Write the two main points in cell theory.
[March 2020]
4. Choose the correct answer.
Microbodies
A structure seen in bacterial cell is……..
•
Single membrane-bound organelles
(a) Nucleus (b) Lysosome
•
Associated with oxidation reactions
•
They are of two types; peroxisomes and
glyoxysomes.
(c) Plastid
(d) Mesosome
[March 2019]
5.
Observe the figure given below :
PREVIOUS YEAR QUESTIONS
1. Choose the correct answer. The organelle
known as the power house of the cell is
(a) Ribosome
(b) Vacuole
(c) Mitochondria
(d) chloroplast
[March 2020]
2. Peculiarities of certain cell organelles are
given below:
(a) Involved in protein synthesis
(b) Made up of many flat, disc shaped sacs or cisternae
(c) Bear ribosomes on their surface
(d) Rich in hydrolytic enzymes
Identify the parts (A) ,(B). Write their func
tions.
[March 2019]
6. Ribosome are organelles without a membrane found in all cells. Name another organelle devoid of membrane, seen in animal
cells. Write its functions.
[March 2018]
(e) Membrane is absent
[March 2020]
Copy the table given below and write the
above peculiarities in appropriate column.
Lysosome
Golgi apparatus Ribosome
7. (a) Identify a cell organelle which contains
hydrolytic enzymes
(b) Rough Endoplasmic Reticulum (RER)
and smooth Endoplasmic Reticulum
(SER) are morphologically and functionally different. Justify this statement.
[March 2017]
[March 2020]
3. Cell theory was formulated by two scientists.
Plus I Biology
8. Observe the given diagram. Analyze this
diagram and explain the structure of plasma
membrane.
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Never give up, never stop learning • 362 .
kinds of chromosomes, of this which is
metacentric non - satellite chromosome?
Justify
your
answer.
[March 2016]
9. (a) Due to the presence of a secondary constriction a knob - like small fragment
appears in some chromosome called—
—
(i) Kinetochore
(ii) Histone
(iii) Satellite
(iv) Chiasmata
(b) Classify chromosomes based on the position of centromere.
[March 2013]
13. An accepted model of structure of a cell
membrane was proposed by singer and
Nicolson.
(a)
Name the model.
(b)
List two major biomolecules which
this membrane is composed of.
(c)
Mention two important points of this
model from the point of view of
function.
[March 2015]
10. State whether the statements are ‘True’ Or
‘False’, correct the statements by changing
the underlined words.
(a) Aleuroplasts store Carbohydrates.
(b) The centrioles form the basal body of
cilia and flagella.
(c) Ribosomes are not surrounded by membranes.
14. Observe the given relation and fill the
blanks
(a) Plumule : Coleoptile
Radicle : ………….
(b) Starch : Amyloplast
(d) RER is the major site for synthesis of
lipids.
[March 2014]
11. Prokaryotic cells posses a special membranous structure which is formed by the extensions of the plasma membrane in the
form of vesicles, tubules and lamellae.
Identify this structure and write any one of
its functions.
Fat
: ……….
[March 2013]
15. The following is a list of cell organelles:
( Nucleus, endoplasmic reticulum, lysosomes, Chloroplast, golgi complex, mitochondria, ribosome)
(a) Identify the organelles with double
membrane envelope.
[March 2014]
12. The diagrams a,b,c given below show three
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(b) Mention the functions of these organelles.
1.
…………..
[Sep. 2012]
2. ……………
[March 2010]
16. (a) Identify the cell organelle found in eukaryotic and prokaryotic cells.
19. Given below are the diagrams of two chromosomes:
(b) Justify its presence in both types of
cells.
(a) Identify the chromosome types (1) and
(2)
[March 2012]
(b) Write the peculiarity of chromosome
17. Match the following :
(a) Synthesis of (i) Golgi appastorage and
ratus
energy
(b) Packing and (ii) Mitochondelivary of
dria
materials
(c) Digestion of (iii) Centriole
intercellular
materials
[March 2009]
20. Choose the most appropriate answer and
fill in the blanks.
(d) Formation
of basal
body of cilia
and flagella
(iv) Lysosome
Crystal violet is used ………...
(i) as dye
(ii) for gram staining
(iii) as a food additive (iv) as an insecticide
(v) Chloroplast
[March 2008]
[March 2012]
18. Label the marked parts in the given diagram of chloroplast.
21. Bacterial cell envelop is a complex structure. It is made up of various layers. Name
the different layers in the bacterial cell envelope.
[March 2007]
22. Mitochondria is called power house of cell.
Comment.
23. Different Types of chromosomes based on
the position of centromere are given below. Classify them with necessary explanation. What is the peculiarity of the chromosome ‘D’?
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Make your parents proud and be happy yourself • 364 .
4.
5.
[March 2007]
Cell wall and middle lamellae are transversed by
(a)
Plasmodesmata
(b)
Primary wall
(c)
Cytoplasm
(d)
Cortex
Important site for the formation of glycoprotein and glycolipid is
(a)
Lysosomes
Important Questions
(b)
Golgi apparatus
1.
(c)
Vacuoles
(d)
Plastids
Schwann proposed a cell theory according to which
(a)
The leucoplasts that store oils and fats.
Amyloplasts
Each cell of body posses the same
genetic information.
(b)
Elaioplasts
(c)
Aleuroplasts
(c) Bodies of animals and plants are
made up of cells and their products.
(d)
Glyceroplasts
(d)
3.
6.
(a)
(b)
2.
All the activities of the organisms
are present in miniature form in
every cell of body.
A new cell always developed by
the division of pre - existing cells.
7.
Omnis cellula - e cellula (all cells arise
from pre-existing cells). Who gave this
concept and modified the cell theory ?
(a)
Schleiden and Schwann
(b)
Virchow
(c)
Robert Brown
(d)
Leeuwenhoek
8.
The cell organelle that is present in cytoplasm as well as other organelle
The cells that lack nucleus are :
(a)
Erythrocytes of many mammals
(b)
Tube cells of vascular plants
(c)
Lymphocytes of mammals
(d)
Both (a) and (b)
What is the function of polysome ?
(a)
Active protein synthesis
(b)
Formation of multiple copies of
same polypeptide
(c)
Both (a) and (b)
(d)
None of the above
(a)
Mitochondria
(b)
Ribosome
(c)
Chloroplast
Which of the following features is common to prokaryotes and many eukaryotes ?
(d)
ER
(a)
Plus I Biology
9.
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Chromatin material present
Cell: The Unit Of Life
Be a better listener to be a better speaker • 365 .
10.
(b)
Cell wall present
(c)
Nuclear membrane present
(d)
Membrane bound subcellular organelles present
What is tonoplast ?
(a)
Outer membrane of mitochondria
(b)
Inner membrane of chloroplast
(c)
Membrane boundary of the vacuole
of plant cells
(d)
11.
Cell membrane of a plant cell
Match the following columns :
Column I
Name the scientist who proposed
fluid mosaic model.
(b)
Name and explain the two types of
proteins in cell membrane.
14.
Pili and Fimbriae are surface structures
of the bacteria. Write the function of
such structures in bacteria.
15.
Mention any four functions of cell wall
in a eukaryotic cell.
16. Ribosomes are present in the cytoplasm
and certain cell organelles of eukaryotic
cells.
(a)
Name two cells organelles which
contain ribosomes.
(b)
How do ribosomes seen in these
cell organelles differ from ribosomes each seen in the cytoplasm
of eukaryotes.
Column II
(a) Centriole
1.
Infoldings
(b) Chlorophyll
2.
Thylakoids
(c) Cristae
3.
Infolding
of
plasma membrane in pro-
(d) Mesosome
(a)
4.
of
Basal body of
Previous Year Question Answers
1.
2.
12.
Column I
(c) Mitochondrion
Column II
Lysosome
Golgi appa-
Ribosome
Rich in hydrolytic enzymes (d)
Made up of
Involved in
many flat,
protein syndisc shaped thesis. Memsacs or cister- brane is abnae (b)
sent (a), (e)
(a) Lysosomes
1.
Protein synthe-
(b) Ribosomes
2.
Hydrolytic ac-
(c) SER
3.
Steroid synthe-
•
All living organisms are composed
of cells and product of cells.
(d) Centriole
4.
Formation
•
All cells arise from pre-existing
cells.
13.
of
An improved model of structure of cell
membrane known as fluid mosaic model
was proposed in 1972.
Plus I Biology
3.
Schleiden and Schwann
4.
d) Mesosome
5.
(A) Grana/thylakoid
(B)
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Stroma
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Reading lights up your world • 366 .
Grana function: Light reaction/
Photophosphorylation.
teins and carbohydrates.
•
Peripheral proteins lie on the surface of membrane while the integral proteins are partially or totally
buried in the membrane.
•
The quasi fluid nature of lipid enables lateral movement of proteins
within the overall bilayer. (any
three structural features)
Stroma function: Dark reaction/
Biosynthetic phase/ Carbon fixation.
6.
Centrioles/ Centrosome/ Diplosome
Functions : Cell division, formation of
basal body of flagella or cilia, spindle
apparatus during cell division.
7.
(a) Lysosomes
9.
(a) (iii) Satellite
(b)
(b)
Metacentric chromosome
The endoplasmic reticulum bearing
ribosomes on their surface is called
Rough Endoplasmic Reticulum
(RER).
In the absence of ribosomes they
appear smooth and are called
Smooth Endoplasmic Reticulum
(SER)
RER involved in protein synthesis
and secretion. They are extensive
and continuous with the outer
membrane of the nucleus.
SER is the major site for synthesis
of lipid. In animal cells lipid like
steroidal hormones are synthesized
in SER.
8.
Submetacentric chromosome
Acrocentric chromosome
Telocentric chromosome
10.
11.
•
Cell membrane is composed of lipids that are arranged in bilayer.
Hydrophobic tails towards the inner part.
•
Lipid components of the membrane
mainly consist of phosphoglycerides.
•
True
(c)
True
(d)
False. SER is the major site for
synthesis of lipids.
Mesosome
12.
Diagram (b). Middle centromere/Two
equal arms/ No secondary constriction/
No satellite
13.
(a)
Fluid mosaic model
(b)
Lipid, protein, sugar, cholesterol,
phospholipid
(c)
Cell growth, formation of intercellular junction, secretion, endocytosis, cell division, fluid nature of the
membrane, passive transport, active transport.
Lipids are arranged within the
membrane with the polar head towards the outer side.
•
(b)
Cell wall formation, DNA replication,
respiration, secretion, increase surface
area of plasma membrane.
Fluid mosaic model of plasma membrane .
•
(a) False. Aleuroplasts store proteins.
14.
(a) Coleorhiza
(b) Elaioplast
Cell membrane also possess pro-
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15.
(a) Nucleus, Mitochondria, Chloroplast
(b)
Nucleus : Controlling centre of all
the activities of the cell, RNA synthesis.
22.
Mitochondria are the centres of production, storage and distribution of energy
for various metabolic activities of cell.
23.
(A) Acrocentric chromosome : The centromere is near the end of the chromosome.
Mitochondria : Cellular respiration/ production of energy/ power
house/ ATP production/ Kreb’s
cycle/ Oxidative phosphorylation.
Chloroplast : Light Reaction/ photosynthesis/ CO2 reduction/ Dark
reaction/ Light absorption.
16.
17.
(c)
(d)
(C)
Submetacentric chromosome : The
centromere is near the middle of
the chromosome.
(D) Metacentric chromosome : The
centromere is at the middle of the
chromosome . Chromosome ‘D’
has both secondary constriction
and a satellite.
Protein synthesis
It is a non-membranous structure.
(b)
Submetacentric chromosome : The
centromere is near the middle of
the chromosome.
(a) Ribosomes
(b)
(a)
(B)
Synthesis and (i) Mitochondria
storage of energy
Packaging and (ii) Golgi apparatus
delivery of materials
Digestion
of (iii) Lysosome
intercellular
materials
Formation of (iv) Centriole
basal body of
cilia and flagella
18.
1. Granum 2. Stroma lamella
19.
(a)
1. Metacentric
(b)
1. Presence of secondary constriction
2. Acrocentric
Important Question Answers
1.
(c) Bodies of animals and plants are
made up of cells and their products .
2.
(b) Virchow
3.
(b) Ribosome
4.
(a) Plasmodesmata
5.
(b) Golgi apparatus
6.
(b) Elaioplasts
7.
(d) Both (a) and (b)
8.
(c) Both (a) and (b)
9.
(b) Cell wall present
10.
(c) Membrane boundary of the vacuole
of plant cells.
Presence of satellite. Centromere is
at the centre
20.
(ii) For gram staining
21.
Glycocalyx
Cell wall and plasma membrane
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11.
damage and infection
Column I
(3)
Helps in cell-to-cell interaction
(4)
Provides barrier to undesirable
macromolecules
(a)
Mitochondria and chloroplast
(b)
Cytoplasmic ribosomes are 80S
and ribosomes in cell organelles
are 70S.
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Column II
(a) Centriole
4.
Basal body of
cilia & flagella
(b) Chlorophyll
2.
Thylakoids
(c) Cristae
1.
Infoldings of
mitochondria
(d) Mesosome
3.
infolding
of
plasma membrane in prokaryotes
16.
12.
Column I
Column II
(a) Lysosomes
2.
Hydrolytic ac-
(b) Ribosomes
1.
Protein synthe-
(c) SER
3.
steroid synthe-
(d) Centriole
4.
Formation
13.
of
(a) Singer and Nicolson
(b)
Peripheral proteins and integral
proteins
Peripheral proteins are arranged on
the surface and integral proteins
are partially or totally buried in the
membrane.
14.
15.
In some bacteria, they are known to help
(a)
Attach the bacteria to rocks in help
(b)
Attach to the host tissues
(1)
Gives shape of the cell
(2)
Protects the cell from mechanical
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CHAPTER 9
BIOMOLECULES


Biomolecules -Chemical compounds found
in living organisms.
A biomolecule is a molecule that naturally
occurs in living organisms.
Minerals
Minerals are grouped as major and minor
based on their amount required by cells.
Formation of zwitterion
An amino acid in solution can have charged
amino group, (NH3+ ) both amino and carboxylic group charged (NH3+ & COO- ) or
charged carboxylic group. If both amino group
and carboxyl group are charged, it is called
Zwitterionic form.
The major minerals of the animal body are:
Calcium Phosphorus, Sodium, Chlorine, Magnesium, Sulphur.
The minor minerals are: Iron, Copper, Cobalt,
Manganese, Molybdenum, Zinc, Fluorine, lodine, Selenium.
Zwitter ion
Lipids
Carbohydrates, Lipids, Amino acids, Proteins,
Nucleic acids, Hormones, Vitamins etc.
They are water-insoluble compounds containing carbon and hydrogen but less oxygen than
that found in carbohydrates. They are high energy organic compounds.
Amino acids
Classification of lipids
Organic compounds:
 Amino
acids are organic compounds containing an amino group (-NH2) and carboxyl
group (-COOH).
 Amino
acid consists of carbon, hydrogen, an
amino group, carboxyl group and a side
group designated "R", which distinguishes
one amino acid from another.
Based on the number of amino and carboxyl
groups, amino acids are classified into three.
They are:
Lipids are classified into three main types,
namely:

Simple Lipids

Compound lipids

Derived lipids
Fatty acids
They are organic acids having hydrocarbon
chains (a chain of carbon and hydrogen atoms)
that end in a carboxyl group (- COOH).

Acidic amino acids eg: Aspartic acid

Basic amino acids, eg: Lysine

Saturated fatty acids.

Neutral amino acids, eg: Valine

Unsaturated fatty acids.
• A particular property of amino acids is the
ionizable nature of –NH2 and -COOH
groups.
Plus I Biology
Fatty acids are of two main types. They are:
Saturated fatty acids do not possess double
bonds in their carbon chains. Eg: Palmitic acid.
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CH₂-(CH₂)14-COOH (Palmitic acid)
Polysaccharides (carbohydrates)
Unsaturated fatty acids possess one or more
double bonds in their carbon chains.
Lipids
Eg: Arachidonic acid.
Nucleic acids.
Nucleotides
Proteins

A nucleic acid molecule is a long chain
polymer (polynucleotide) composed of
monomeric units called nucleotides.

Nucleotides are the basic units of nucleic
acids.
Proteins

Proteins are polymeric molecules in which
the subunits are monomers of amino acids
which are covalently linked to each other
by peptide bonds.

Each protein is a polymer of amino acids.
Amino acids can be classified as essential
or non essential amino acids.

Each nucleotide consists of a nucleoside
and phosphate group.


Each nucleoside consists of a sugar molecule and a nitrogen base.
Structure of Proteins.

The sugar is ribose in the case of RNA
(ribonucleic acid) and deoxyribose in the
case of DNA (deoxy ribonucleic acid)

Each protein possesses a characteristic
three dimensional shape.

In describing the three-dimensional structure of proteins it usually refers to four,
separate levels of organization as given below:

DNA and RNA function as genetic materials.

Adenine, guanine, cytosine, uracil and thymine are the nitrogen bases.

Primary structure

Adenosine, guanosine, thymidine, uridine
and cytidine are nucleosides.

Secondary structure

Tertiary structure

Adenylic acid, thymidylic acid, guanylic
acid, uridylic acid and cytidylic acid are
nucleotides.

Quarternary structure
Biomacromolecules
Micro molecules
Primary Structure:
The primary structure of a protein refers to its
unique number and sequence of amino acids
linked by peptide bonds in a polypeptide chain.
They are small organic molecules that give rise
to macromolecules on polymerization.
Macromolecules
Large organic molecules, characteristic of living organisms.
Biomacromolecules of the cell are categorized
into four main classes. They are:
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Secondary structure:
The secondary structure of proteins refers to
the spatial arrangement of polypeptide chains
as a result of hydrogen bond formation. The
 − (alpha) helix and the B-pleated sheet are
best examples of secondary structure.
Polysaccharides
They are long chain of sugars.
Monosaccharides (Simple carbohydrates having only one sugar or saccharide molecule in
their constitution) are the building blocks of
polysaccharides
Tertiary structure:
When a long peptide chain, with or without a
helix, is coiled and variously folded in itself,
the resulting highly specific three dimensional
configuration of the protein is termed the tertiary structure.
i.e.; polysaccharides are the polymerized forms
of monosaccharides.
There are two important classes of polysaccharides regarding their composition. They are:Homopolysaccharides:
Heteropolysaccharides:
Nucleic acids
Nucleic acids are important macromolecules of
the cell. These are complex, long-chain compounds larger than most proteins containing
carbon, oxygen, hydrogen, nitrogen and phosphorus. There are two kinds of nucleic acidsDNA and RNA.
Watson - Crick Model:
One of the secondary structures exhibited by
DNA.
Quaternary structure:
A protein is said to have quaternary structure if
it is composed of several polypeptide chains
which are not covalently linked to one another.
Each polypeptide chain in such a protein, is
called sub unit
Plus I Biology

According to this model, DNA exists as a
double helix.

The two strands of polynucleotides are antiparallel i.e., run in the opposite directions.

The backbone is formed by the sugarphosphate-sugar chain.
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
A and G of one strand compulsorily base
pairs with T and C, respectively on the other strand.

There are two hydrogen bonds between A
and T (A = T)

There are three hydrogen bonds between G
and C (G=C)

energy in order to undergo a particular chemical reaction.
Each strand appears like a helical staircase.
Enzymes
Active site: An area of enzyme surface which
has a shape complementary to a particular substrate, enabling the enzyme and substrate to
become temporarily bonded to form an enzyme
substrate complex.
Substrate: The chemical which is converted
into a product is called a substrate.
The catalytic cycle of enzyme action.
Factors affecting enzyme activity
Temperature

Substrate binds to the active site of the enzyme, fitting into the active site.

The binding of the substrate induces the enzyme to alter its shape.
Substrate concentration
The active site of the enzyme breaks the
chemical bonds of the substrate and the new
enzyme - product complex is formed.
Temperature and PH


The enzyme releases the products of the reaction.

The free enzyme repeats the process.
Nature of enzyme action
Enzyme molecule (E) + Substrate molecule (S)
→ Enzyme substrate complex (ES)
E+S↔ ES Complex→ EP complex → E+ P
The energy level difference between substrate
and product is not affected in the enzyme action.
Activation energy:
Extra energy that must be possessed by atoms
or molecules in addition to their ground-state
Plus I Biology
pH.
Binding of specific chemicals.

Each enzyme shows its highest activity at a
particular temperature and pH.

The characteristic pH at which an enzyme
has maximal catalytic activity is called optimum pH.

Low temperature preserves the enzyme in
a temporarily inactive state whereas high
temperature destroys enzymatic activity
because proteins are denatured by heat.
Concentration of substrate
With the increase in substrate concentration,
the velocity of the enzymatic reaction rises at
first. The reactions ultimately reaches Vmax.
Vmax is the maximum velocity of an enzymatic
reaction when the binding site is saturated with
substrate.
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between a pair of substrates.
3. Hydrolases
Enzymes catalyzing hydrolysis of ester,
ether, peptide, glycosidic bonds.
4. Lyases
Enzymes that catalyse removal of groups
from substrates by mechanisms other than
hydrolysis leaving double bonds.
5. Isomerases
Includes all enzymes catalyzing inter conversion of optical geometrical or positional
isomers.
6. Ligases
Enzymes catalyzing the linking together of
2 compounds
Cofactors
Non-protein constituents which are bound to
the enzyme to make the enzyme catalytically
active are called cofactors. In it, the protein
portion of the enzymes is called the apoenzyme. Three kinds of cofactors may be identified: They are:
Binding of specific chemicals:
When the binding of the chemical shuts off
enzyme activity, the process is called inhibition and the chemical is called an inhibitor.
Prosthetic groups
Coenzymes
Competitive inhibitor:
Metal ions.
When the inhibitor closely resembles the substrate in its molecular structure and inhibits the
activity of the enzyme, it is known as competitive inhibitor.
Prosthetic groups are organic compounds and
are distinguished from other cofactors in that
they are tightly bound to the apoenzyme. For
example, in per oxidase and catalase, which
catalyze the breakdown of hydrogen peroxide
to water and oxygen, haem is the prosthetic
group and it is a part of the active site of the
enzyme.
Classification and nomenclature of enzymes.
Enzymes are divided into six classes.
1. Oxido reductases/ dehydrogenases
Enzyme which catalyse oxidoreduction between 2 substrates S and S.
2. Transferases
Enzymes catalyzing a transfer of a group
Plus I Biology
Coenzymes are also organic compounds but
their association with the apoenzyme is only
transient, usually occurring only during the
course of catalysis. ie. co-enzymes serve as
cofactors in a number of different enzyme cat-
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alyzed reactions. The essential chemical components of many coenzymes are vitamins, e.g.
coenzyme nicotinamide adenine dinucleotide
(NAD) and NADP contain the vitamin niacin.
A number of enzymes require metal ions for
their activity. Catalytic activity is lost when the
cofactor is removed from the enzyme.eg: Zinc
is a cofactor for the proteolytic enzyme carboxy peptidase.
PREVIOUS YEAR QUESTIONS
1.
3.Nonprotein constituents called cofactors are
bound to the enzyme to make the enzyme catalytically active.
[March:2011]
a.Name the protein portion of the enzyme.
a. Identify this compound.
b. Name the bond produced when another biomolecules of the same category combines with this.
c.If a number of such molecules are bonded
together, what will be the resultant molecule?
[March 2013]
2. Observe the molecule given below and answer the following questions.
[March 2012]
a.Identify the molecule.
b.What happens to the catalytic activity
when the cofactor is removed from the enzyme?
c.Mention any two kinds of cofactors with
examples.
4. Obser the graph.
a. What is meant by ’Vmax’ value?
b.Why is ’Vmax’ not exceeded by any further rise in the substrate concentration?
c.If a chemical substance closely resembling to that of a substrate is introduced
into the reaction system, what will be
the consequences? Substantiate.
b.Label 1 and 2.
[March:2010]
c.Mention any three structural details of the
molecule shown in the diagram.
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5. Fill int the blank columns with the correct
terms/sentences.(3 scores) [March:2009]
A
IMPORTANT QUESTIONS
B
………………
….
Catalyze oxido-reduction
two substrates
Transferase
………………………….
……………….. Catalyse hydrolysis of ester, glycosidic or C-C
bonds.
Lyse
………………………….
……………….. Catalyse interconversion
of optical or geometric
isomers.
Ligase
agree to it? Which is the glycosidic linkage of
lactose and its monomers?
…………………………..
6. The diagram given below shows a segment
of double-stranded DNA. Copy it and label the
parts marked a and b.
[March:2008]
7. The body of organisms are composed of
four main classes of macromolecules . List out
the macromolecules.
[March:2007]
8. Which of the following is stronger in a DNA
double helix?
[March 2006]
1.
By observing the relationship between
the first pair, fill up the blanks.
(a) Cellulose : Polysaccharide
DNA : ………..
(b) Adenine : Purine
Thymine : ……
2. …….. Is considered as the most abundant
protein in the biosphere.
3. Amino acid proteins : Peptide bond.
Monosaccharides Polysaccharides:…….
4. What role does temperature play in food
preservation?
5. Identify the protein structures A and B from
the following figures.
6. Which of the following amino acids is Zwitter ion, A or B or C?
9. Enzymes are biocatalysts. What do you understand from the given sequence of enzyme
action?
[March:2006]
E+S
ES
E+P
10. Maltose is a disaccharide of 2 glucose molecules linked by the glycosidic linkage of C1
7. Egg albumin is a protein. When you boil egg
the albumin solidifies. Why is this happening?
Of the glucose and C4 of the other. Do you
8. Fill the gap.
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Inhibition of succinic dehydrogenase by malonate is an example for …………………..
c. DNA has ………. Instead of uracil
9. Observe the mode of action given below.
17. Enzymes have been classified into different groups based on the type of reaction they
catalyse. Note the classes of enzymes.
E + S→ ES →Ep → E → P
Mention any two factors controlling it.
10. Observe the diagram of a functional enzyme given below and identify the marked regions in the figure.
d. The protein part of a enzymes is…..
18. The figure shows the bonding of a biomolecule .
a.Identify the monomer.
b.Name the bond between the molecule.
c.Name the macromolecule formed.
PREVIOUS YEAR QUESTIONS ASNWERS
1.
11. “Living state is a non-equilibrium steady
state”. Do you agree with this statement?
Justify your answer.
(a) Glycine
(b) Peptide bond
(c) Protein
2. (a) Watson and Crick model of DNA
12. Arrange the following carbohydrates in the
order of increasing complexity of chemical
structure.[ oligosac charides, Hemi cellulose,
glucose, starch]
13. classify the following as polypeptide and
polysaccharide.
(b) 1. Thymine.
2. Hydrogen bond.
(c) 1. Sugar phosphate back bone
2. Nitrogen bases face inside and are
projected perpendicular to the back
(Insulin, Glycogen, Chitin, Paper, RuBisCo)
14. Amino acids, rubber, drigs sugar, and spices, classify them into primary and secondary
metabolites.
15. What is the significance of attaining tertiary structure by proteins?
16. Add suitable word in the gap.
a.
3.A pairs with T by two hydrogen bonds
and G pairs with C with three hydro
gen bonds.
3. (a) Apoenzyme
(b) Catalytic activity decreases
A protein molecule is a polymer of …….
b. Nucleic acids are polymers of………
Plus I Biology
bone.
(c) 1. Prosthetic group eg: Heaem
2. Co-enzyme, eg: NAD,NADP, FAD,
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FADP.
7. 1. Carbohydrates,
4. (a) maximum velocity
2. Lipids
(b) At this state, the enzyme molecules
become fully saturated and no active site is
left free to bind with the additional substrate
molecule. All enzymes show this saturation
effect.
3. Proteins
(c) It will inhibit the enzyme activity. As
a result, the reaction will stop.
5.
4. Nucleic acids.
8. C— G
9. In an enzyme action, the enzyme (E) reacts
with substrate (S) to form an enzyme– substrate complex (ES). It then splits up into the
enzyme (E) and the product (P).
10. Yes, Covalent Bond.
A
B
Oxidoreductase
Catalyse oxido-reduction between two substrates
Transferase
Catalyse group transfer between substrates.
Hydrolase
Catalyse hydrolysis of ester,
glycosidic or C-C bonds.
Lyse
Removal of group from a
substrate by clearing gouble
bonds
Isomerase
Catalyse intersronversion of
optical or geometric isomers.
Ligase
Catalyse linking together of
two compounds
IMPORTANT QUESTIONS ANSWERS
1.
(a) Nucleic acid
(b) Pyrimidine.
2. RuBisCo.
3. Glycosidic bonds.
4. Enzymes in the food is inactivated at very
low temperatures, on gradual increase in temperature the enzyme activity is regained.
5. A - Secondary structure B– Tertiary structure.
6. B
7. The conformation of protein is changed by
temperature and the protein becomes denatured.
8. Competitive inhibition.
9. 1. Temperature
6.
2. pH
10. A– Apoenzyme B– Co-factor.
11. Yes. Because, 1. Biomolecules are present
in a biological system in definite concentrations.
2. Systems at equilibrium cannot perform
work but living organisms work continuously.
12. 1. Glucose
2. Oligosaccharides.
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3. Hemicellulose
4. Starch
13.
Polypeptide
Polysaccharide
1. RuBisCo
1. Glycogen
2. Chitin
3. Insulin
4. Paper
14.
Primary metabolites
Secondary metabolites
1. Amino acids
1. Rubber
2. Sugar
2. Drugs
3. Spices
15. Tertiary structure bears crevices called active sites. Active sites are essential for substrate binding during enzymatic reaction.
16. (a) Amino acids
(b) Nucleotides
(c) Thymine
(d) Apoenzyme.
17. 1. Oxidoreductases
2. Transferases
3. Hydrolases
4. Lyases
5. Isomerases
6. Ligases.
18. (a) Glucose
(b) Glycosidic bond
(c) Polysaccharide
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CHAPTER 10
CELL CYCLE AND CELL DIVISION
• Chromatid
One of the two identical longitudinal
1.
Interphase
2.
M Phase
halves of a chromosome.
• Centromere
A button like structure occurring between
the chromosomal arms of chromosomes.
•
Centrioles
Cylindrically-shaped cytoplasmic orga
nelles in animal cells which appear just
outside the nucleus. It has no membrane.
•
spindle fibres
Interphase:
Fine threads of contractile protein which
carry chromosomes during cell division
•
Kinetochores
Small disc-shaped structures at the sur
face of the centromeres
•
Bivalent
Paired homologous chromosomes formed
during meiosis
•
Tetrad
The four homologous chromatids which
associate during prophase and metaphase of
meiosis and are involved in crossing-over.
Cell cycle
Plus 1 Biology
• The inter phase is also called the resting
phase.
• It is the time during which the cell is preparing for division by undergoing both cell
growth and DNA replication in an orderly
manner. It is biosynthetically the most active phase.
• The interphase is divided into three further
phases:
G1 phase (Gap 1)
S Phase (synthesis)
G2 Phase (Gap 2)
Cell cycle: The sequence of events which a
cell duplicates its genome, synthesises the
other constituents of the cell and eventually
divides into two daughter cells is termed
cell cycles
Basic phases of cell cycle
• It represents the phase between two successive M phases.
G1 phase
• The interval between mitosis and initiation
of DNA replication.
• During G1 phase, the cell is metabolically
active and it continuously grows but does
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not replicate its DNA
S phase
• The period during which DNA synthesis or
replication takes place.
Mitosis is divided into the following four
stages:

Prophase
• During this time the amount of DNA in the
cell doubles.

Metaphase

Anaphase
• However, there is no increase in the chromosome number.

Telophase
• In animal cells, DNA replication begins in
the nucleus, and the centriole duplicates in
the cytoplasm.
G2 phase
•
Proteins are synthesised for mitosis.
•
Cell growth continues.
Quiescent stage (G0)
•
The cells that do not divide further exit G1
phase to enter an inactive stage called quiescent stage (G0) of the cell cycle eg: Heart
cells.
•
Cells at this stage remain metabolically active. but no longer proliferate unless called
on to do so depending on the requirement
of the organism.
M phase (Mitosis phase)
The phase when the actual cell division or mitosis occurs. It has two stages. They are:
Karyokinesis- It is the division of the nucleus, that is, the separation of the chromosomes.
Cytokinesis -It is the division of the cytoplasm
M phase (Mitosis phase)
Process of Mitosis
Prophase:
Mitosis
•
In mitosis, the nuclear content of a cell reproduces and divides, resulting in the formation of
two new daughter cells, each containing the
diploid number of chromosomes.
It is the first stage pf mitosis following the
S and G2 phases of interphase.
•
Chromosomal material condenses to form
compact mitotic chromosomes.
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•
•
Chromosomes are seen to be composed of
two chromatids attached together at the
centromere.
Anaphase
The centriole, which had undergone duplication (doubling) during the S phase of
interphase, now begins to move towards
the opposite poles of the cell.
• Chromatids move to opposite poles.
•
The assembly of mitotic spindle begins.
•
Golgi complexes, endoplasmic reticulum,
nucleolus and the nuclear envelope disappear.
• Centromeres split and chromatids (now
called chromosomes separate).
•
The number of chromosomes at each end
of the cell equals the original number.
Telophase
• This is the final stage of mitosis.
Metaphase
• Spindle fibres get attached to the kinetochores of chromosomes
• Chromosomes line up randomly at the centre of the cell between the spindles, along
the metaphase plate. Metaphase plate is seen
at the equatorial region of the cell.
• Chromosomes cluster at opposite spindle
poles and their identity is lost as discrete
elements.
• Nuclear envelope assembles around the
chromosome clusters.
• Nucleolus, golgi complex and ER are
formed again. Now we can say that karyokinesis has been completed.
• The centromere of each chromosome replicates.
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Syncytium - In some organisms karyokinesis
is not followed by cytokinesis. As a result of
this a multinucleate condition arises which is
called syncytium.
The key features of meiosis:
eg. Liquid endosperm in coconut
• Meiosis involves two sequential cycles of
nuclear and cell division called meiosis I,
meiosis II but only a single cycle of DNA
replication.
• At anaphase stage, each separated chromatid is considered as a complete chromosome.
• Meiosis I begins after the replication of parental chromosomes in the 'S' phase of interphase.
Significance of mitosis
• Meiosis involves pairing of homologous
chromosomes and recombination between
them.
•
Restricted to diploid cells
•
Chromosome number remains the same in
all vegetative cells.
•
The genetic constitution of the daughter
cells is the same as that of the parent cell.
•
Mitosis helps the body growth of multicellular organisms and to repair the damage.
•
It is useful for replacement of lost cells.
•
It helps unicellular organisms to increase in
number.
• Four haploid cells are formed at the end of
meiosis II
Meiosis
• It is a specialised kind of cell division that
reduces the chromosome number in a diploid cell by half, resulting in the production
of haploid daughter cells. Meiosis occurs
during gametogenesis in plants and animals.
• Meiosis involves two division sequences
separated by a resting phase and results in
the formation of four new cells, each having the haploid number of chromosomes.
• Meiosis is called reduction division.
Why?
Meiosis occur in sex organs and the diploid
number of chromosome is reduced to half to
form gametes.
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Meiosis/ Process of meiosis
occurs
First meiotic division
This stage begins with one parent cell and ends
with two daughter cells, each containing the
haploid number of chromosomes.
• Unpairing of homologous chromosomes
starts and Chiasmata are first seen.
• Chiasmata are the points of contact where
interchange of chromosome material takes
place between chromatids of two homologous chromosomes.
Diakinesis
•
It is the final stage of meiotic prophase I
• Terminalisation of chiasmata occurs. Chromosomes are fully condensed.
• Meiotic spindle is assembled.
• Nucleolus disappears and the nuclear envelope breaks down.
Phases

Prophase I
Leptotene
The chromosomes are long, thin and threadlike at this stage and gradually visible under
light microscope.
Zygotene
• Synapsis occurs. It is the pairing of homologous chromosomes. 4 distinct chromatids
are seen and is called tetrad stage.
• Synaptonemal complex is formed - (It is a
structural component situated between a
pair of synapsed homologous chromosomes).
Pachytene
Recombination nodules appear. These are the
sites at which crossing over (exchange of genetic material between two homologous chromosomes) occurs between non-sister chromatids of the homologous chromosomes. This
results in recombination of genes.
Diplotene
• Dissolution of the synaptonemal complex
Plus 1 Biology

Metaphase I.
• Pairs of bivalent chromosomes line up randomly along the metaphase plate.
• Spindle fibres attach to each chromosome
pair; centromeres do not replicate.
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
Anaphase I
•
The bivalent pairs separate, with spindle
fibres pulling the homologous, double
stranded chromosomes to the opposite ends
of the cell. Reduction in chromosome number occur at this phase.
•
Because the centromeres have not divided,
the chromatids remain attached.

Telophase I
• The nuclear membrane and nucleolus reappear.
• Telophase I is followed by cytokinesis in
which the cytoplasm compresses and divides the cell into two halves.
• Each new cell contains the haploid number
of chromosomes.

Interkinesis
•
This is a short interval between the two
meiotic divisions
• The nucleus and nuclear mem brane are
well defined.
• Each chromosome consists of two chromatids that do not replicate.
Second Division
This stage is essentially a mitotic division. It
begins with two new daughter cells, each containing the haploid number of chromosomes,
and ends with four new haploid cells.
Prophase II
•
The nuclear membrane disappears
•
The chromosomes again become compact;
they do not synapse
Metaphase II
• Chromosomes align at equator. Spindle fires
attach to the centromere.
Anaphase II
•
The chromatids separate; each is now a
singlestranded chromosome.
• Chromosomes move away from one another and are pulled to the opposite ends of the
cell.
Telophase II
• Meiosis ends with telophase II
• The two groups of chromosomes once
again get enclosed by a nuclear envelope.
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• After telophase II, cytokinesis follows. In
this process, the cytoplasm of each cell
compresses and divides the cells into two
halves leaving a total of four new daughter
cells each containing the haploid number of
chromosomes.
A
B
Zygotene
(a)
(b)
Crossing over
(c)
Dissolution of synaptonemal
complex
Diakinesis
(d)
Significance of meiosis
• Four haploid daughter cells are formed
from a single diploid cell.
• The chromosome number is restricted to
half in the gametes.
• Avoids unnecessary duplication of chromosomes in fertilization.
• Genetic variation occurs in offspring due to
the exchange of genetic material during
crossing over.
•
(March 2020)
3.
The stage at which synapsis occurs during prophase 1.
(2020)
4.
Meiosis maintains the chromosome number of a species constant.
• Helps to maintain vigour in the progeny
through sexual reproduction
5.
Previous Year HSE Questions
1.
- - - - - - - : Chromatids move to opposite poles.
( March 2020)
2.
Analyse the table given below and fill in
the blanks.
a)
Write three phases of interphase.
b)
Write the peculiarity of quiescent
stage (G0).
(2020)
Fill in the blank:
6.
Karyokinesis of mitosis is divided into
four stages. Name the second and third
stage. Write any two features of second
stage.
(March 2019)
7.
Crossing over occurs in -------- substage
of prophase 1
8.
Plus 1 Biology
During interphase stage cells prepare for
cell division.
Cytokinesis in animal cell takes place by
the appearance of a ------- in the plasma
membrane.
(March 2019)
Observe the relationship between the
first two terms and fill in the blank.
Metaphase: Spindle fibres attach to kinetochores.
Name of the following:
a)
Leptotene
b)
Zygotene
c)
Diplotene
d)
Pachytene
(2019)
Given below is the diagrammatic representation of a particular stage mitosis:
Winner’s Coaching Centre
Cell Cycle and Cell Division
Exercise changes your attitude • 387 .
(2018)
12.
9.
a)
Identify the stage.
b)
Write any two features of these
stage.
(2019)
First phase of meiosis I is typically longer and complex one. Name it. Mention
the five subdivisions of this phase.
Observe the given stage of mitosis.
Identify the stage and write any two features of it.
(2018)
13.
(March 2018)
10.
Certain stages in cell cycle are given below:
Given below is the metaphase of mitosis.
Analyse the diagram and draw a sketch
of anaphase. Write any two events of
anaphase.
Karyokinesis, prophase, cytokinesis,
metaphase, anaphase, telophase
Choose the statements (from those given
below) that match with these stages and
prepare a table.
•
Centromere split and chromosomes
move to opposite poles.
•
Chromosomes cluster at opposite
poles and nuclear envelope assembles around.
•
Chromosomes seems to be with
two chromatids attached at centromere
•
Chromosomes arranged at spindle
equator.
•
Separation of daughter chromosomes.
•
11.
(March 2017)
14.
Give the scientific term of the following:
Interchange of genetic material between
con-sister chromatids of homologous
chromosomes.
(2017)
15.
“Meiosis is highly significant in sexually
reproducing organism.” Justify. (2017)
16.
(a) identify the substage of meiosis in
which crossing over is occurring.
(i) Leptotene
(ii) Zygotene
(iii) Pachytene
(vi) Diplotene
(b)
Division of Cytoplasm.
Fill in the blanks.
Small disc– shaped structures at the surface of the centromere are called ------
Plus 1 Biology
17.
Summarize the significance of meiosis in sexually reproducing organisms.
(March 2016)
Identify the substages of prophase I of
meiosis in which the following events
Winner’s Coaching Centre
Cell Cycle and Cell Division
To lose patience is to lose battle • 388 .
take place. Mention two significance of
meiosis.
18.
a)
Dissolution of the synaptonemal
complex
b)
Crossing over
c)
Pairing of homologous chromosome
d)
Terminalisation of chiasma of chiasma
(2016)
Observe the diagrams, Identify the A and
B stages of mitosis. Write any two identifying features of each stage
(2016)
19.
20.
Due to the presence of a secondary constriction, a knob– like small fragment
appears
in
some
chromosomes
called……
(March 2015)
Important Questions
1.
Which stage of Meiosis crossing over of
genetic material takes place?
2.
Name the cells in which Meiosis occurs.
3.
Mitosis is characterized by ……….
4.
Which phase is the longest in the cell
cycle?
5.
Cell division that is known as reduction
division is……….
6.
Observe the relationship between the
first two terms and fill in the blank:
Prophase: Nucleolus and golgi complex
disappear
………. : Nucleolus and golgi complex
reform
7.
Observe the diagrammatic view of a cell
cycle and answer the questions.
a)
Identify the phase, in which DNA
synthesis takes place.
b)
Mention any one event that takes
place in the stages marked as X
and Y.
(March 2015)
8.
9.
Plus 1 Biology
Condensation of chromosomes occur in
……….
a)
Prophase I
b)
Prophase II
c)
Anaphase
d)
Metaphase
Which stage is the connecting link between Meiosis I and Meiosis II?
a)
Interphase I
b)
Interphase II
c)
Interkinesis
d)
Anaphase I
Mitosis occurs in
Winner’s Coaching Centre
Cell Cycle and Cell Division
Patience is waiting with good attitude • 389 .
10.
11.
12.
13.
a)
Haploid individuals
b)
Diploid individuals
c)
Both (a) and (b)
d)
In bacteria only
If there were 4 chromosomes present
during prophase, how many chromosomes are there in each cell at the end of
anaphase II?
14.
Anaphase and Anaphase I leads to separation of chromosomes in different ways.
Substantiate the statement with suitable
explanation.
15.
Notice the four stages of mitosis give
below
1)
Prophase
a)
16
b) 4
2)
Metaphase
c)
2
d) 8
3)
Anaphase
4)
Telophase
(a)
Identify the stage at which the
maximum condensation of chromosomes occur.
(b)
Name the stage that follows the
above identified stage and write
any two peculiarities of the stage.
Terminalisation of chiasmata occurs in
which stage?
a)
Pachytene
b)
Diplotene
c)
Zygotene
d)
diakinesis
16.
Choose the correct answer:
Karyokinesis is followed by cytokinesis.
Synapsis is associated with
a)
Define cytokinesis.
a)
Pachytene
b)
b)
Zygotene
Differentiate cytokinesis in plant
cell and animal cell.
c)
Leptotene
d)
Diplotene
17.
Complete the illustration related to cell
cycle appropriately.
During diakinesis terminalization of chiasmata occurs.
a)
Write any other two changes that
occur during this stage.
b)
Identify the stage that follows diakinesis.
18.
Continuation of life mainly depends on
meiotic division. Substantiate.
19.
Using the hints I and II given below ,
make suitable pairs as in the example
provided .
[ Hint I : Synapsis, compaction of chromosomes, dissolution of synaptonemal
complex, crossing over, terminalization
of chiasmata]
[Hint: II zygotene, diakinesis, diplotene,
Plus 1 Biology
Winner’s Coaching Centre
Cell Cycle and Cell Division
Trying now is better than trying later • 390 .
pachytene, leptotene]
20.
Chromatids move to opposite poles.
List the main differences between Mitosis and Meiosis.
9.
Leptotene, Zygotene, Pachytene, Diplotene, Diakinesis
Previous year questions
1.
Prophase I
Anaphase
2.
10.
Zygotene Synaptonemal complex
(a)
Pachytene (b)
Diplotene (c)
Anaphase/ Karyo- Centromere splits
kinesis
and chromosomes
move to opposite
Crossing over
Telophase/ Karyo- Chromosomes
kinesis
cluster at opposite
poles and nuclear
envelope assem-
Dissolution of synaptonemal complex
Diakine- Terminalisation of chisis
asmata (d)
3.
Zygotene
4.
(a) G1 phase, S phase and G2 phase
(b) Metabolically active but no longer
proliferate.
5.
Cleavage furrow
6.
Metaphase, Anaphase
Features of metaphase
1.
Metaphase plate
2.
All chromosomes at equator
3.
Chromosome at maximum condensation
4.
Spindle fibres attached to kinetochores
7.
d) Pachytene
8.
(a) Anaphase
Prophase/
Metaphase/
Karyokinesis
Chromosomes
seem to be with
two
chromatids
attached at centro-
Metaphase/
Karyokinesis
Chromosomes arranged at spindle
Anaphase/
Karyokinesis
Separation
of
daughter chromo-
Cytokinesis
Division of cytoplasm
11.
Kinetochore
12.
Telophase
1.
Chromosomes cluster at opposite
poles.
2.
Nuclear envelope assemble around
chromosome cluster.
(b) Centromers splits and chromatids
separate.
Plus 1 Biology
Winner’s Coaching Centre
Cell Cycle and Cell Division
Investment in knowledge pays the best interest • 391 .
separate.
13.
(2)
Movement of daughter chromosomes towards the opposite poles
of the cell.
19.
Statellite chromosomes
20.
(a) S phase
(b) x-Metaphase
1.
Centromeres split and chromatids separate.
2.
Chromatids move to opposite poles.
14.
Crossing over.
15.
It ensures the conservation of specific
chromosome number.
It causes the variation of genetic character.
16.
a) Pachytene
b) Conservation of specific chromosome
number of each species is achieved
across successive generations in sexually
reproducing organisms through meiosis.
17.
(a) Diplotene
(c) Zygotene
(b)
(d)
Pachytene
Diakinesis
Significance of meiosis
1)
2)
18.
Chromosome number constantly
maintained
Variation occurs and formation of
new species
(a) Metaphase
Chromosomes arranged at the equator.
Y– Anaphase
Centromere divides and chromatids
move towards the opposite poles.
Important question answers
Fill in the blanks
1.
Pachytene
2.
Reproductive cells or germ cells
3.
Equational division
4.
Interphase
5.
Meiosis
6.
Telophase
7.
Prophase I
8.
Interkinesis
9.
Both (a) and (b)
10.
2
11.
Diakinesis
12.
Zygotene
13.
Features
(1)
Formation of spindle apparatus
(2)
Chromosomes are arranged at the
equator
(b) Anaphase
Features
(1)
Plus 1 Biology
Centromers splits and chromatids
Winner’s Coaching Centre
Cell Cycle and Cell Division
Today a reader, Tomorrow a leader • 392 .
14.
Anaphase
Anaphase 1
Centromere splits
and
chromatids
move to opposite
poles
Homologous chromosomes separate
and move to opposite poles while
sister chromatids
remain associated
at their centromeres
15.
20.
Mitosis
In mitotic di- 1. Meiotic division
vision, a sininvolves
two
gle division ,
successive diviresults in two
sions– Meiosis I
daughter
and Meiosis II.
cells.
These divisions
result in four
daughter cells
2.
Mitosis
is 2. Meiosis I is
known
as
known as reducequational
tional division.
division. This
This is because
is because the
the chromosome
daughter cells
number is rehave the same
duced to half.
diploid numMeiosis II is
ber of chroknown as equamosomes as
tional division.
the parent.
This is because
the sister chromatids separate
and the chromosome
number
remains
the
same.
3.
Prophase is 3.Prophase I is very
short and does
long and comnot comprise
prises 5 phases:
any phase.
Leptotene, zygotene, pachytene,
diplotene
and
diakinesis.
(a) Division of cytoplasm
(b) Animal cell: Furrow appear in the
plasma membrane which gradually
deepens and joins in the centre.
Plant cell: Cell plate formation
starts in the centre of the cell and
grows outward to meet the existing
lateral walls.
17.
(a) Chromosomes get fully condensed.
Nucleus disappears and nuclear envelope
breaks down.
(b) Metaphase I
18.
(1) Meiosis is reduction division that
ensures formation of haploid gamete in
sexually reproducing organisms.
(2)
19.
It causes genetic variability tat
leads to evolution.
Leptotene - Compaction of
somes
chromo-
Meiosis
1.
(a) Metaphase
(b) Anaphases: Centromere splits and
chromatids separate.
Chromatids
move to opposite poles.
16.
Diakinesis - Terminalisation of chiasmata
Zygotene - Synapsis
Pachytene - Crossing over
Diplotene - Dissolution of synaptonemal
complex
Plus 1 Biology
Winner’s Coaching Centre
Cell Cycle and Cell Division
Think like a proton, always positive • 393 .
4.
There is no 4. In the zygotene
pairing of stage of prochromophase, the pairsomes,
ing of chromocrossing
somes occurs.
over or chi- During pachyasmata for- tene, crossing
mation dur- over
occurs.
ing
pro- Chiasmata are
phase.
formed in the
5.
Synap5. Synaptonemal
tonemal
complex oi
complex is
formed durnot formed.
ing the zygotene stage of
6.
Anaphase
6.
involves the
separation
of the chromatids
of
each chromosome.
Plus 1 Biology
7.
Mitosis plays 7. Meiosis brings
a significant
about variation
role in the
and maintains
healing repair,
the
chromoand growth of
some number
a cell.
from generation
to generation.
During anaphase I, the
homologous
chromosomes
separate
while
the
chromatids
remain
attached
at
their centromeres. During anaphase
II, the chromatids separate as a result of the
splitting of
the
centromere.
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Cell Cycle and Cell Division