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1. Class 12th Biology 1st Chapter

2. Very Short Answer Type Questions
Q. Define xenogamy.
Ans. It is the transfer of pollen grain from the anther of one flower
to the stigma of genetically different flower.
Q. What is the chemical nature of outer covering of pollen ?
Ans. It provides nourishment to development of embryosac.

3. Q. What is the function nucellus ?
Ans. A type of pollination from one flower to another
flower of same plant.
Q. What is scutellum ?
Ans. It is the one large shielted cotyledon of a monocot
plant . It is the first leaf of a monocot plants.

4. Q. What is apocarpous and syncarpous ?
Ans. Apocarpous ovary have separate carpels and there is
single ovary in syncarpous.
Q. What is autogamy ?
Ans. Self pollination is know as autogamy .
Q. What are germ pores ?
Ans. Prominent apertures present in exine of pollen grain
where sporopollenin is absent.

5. Q. What is coleorrhiza ?
Ans. It is covering of radicle-root cap complec in monocot grams. It
pierces grow covering and stops further growth .
Q. What is Coleoptile ?
Ans. The epicotyl bearing shoot apex and leaf primordia enclosed in
a foliar structure is called coleoptile.

6. Q. What is the function of pollen tube?
Ans. It helps in fertilization carrying male gametes to embryo sac.
Q. Give an example of insect pollinated plant .
Ans. Dahlia .
Q. What is meant by monosporic development of female
gametophyte ?
Ans. When a single megaspore is used in the development of
embryo sac, it is called monosporic development e.g . Polygonum.
Q. What is anemophily ?
Ans. Pollination by wind is called anemophily.

7. Short Answer Type Questions
Q. Draw L.S . Of typical flower showing its parts .
Ans.

8. Q. Draw well labelled diagram of T.S. of anther.

9. Q. (i) With the help of labelled
diagram, describe the structure of
pollen grain of flowering plant.
Ans. (i) Structure of pollen grain .
Pollen grain has double layered
wall. Its inner layer is called intine
and outer layer is Exine.
(a)Intine . It is cellulosic inner layer .
(b)Exine . It is thick, cuticularised
showing spiny outgrowths. It is
made up of sporopollenin. Exine
may be thin or absent at certain
places. These are called
germpores (3 in dicots and one in
monocots). It can with stand high
temperature, acids , alkalis.

10. Q. (ii) How do pollen grains of many species affect human health ?
Ans. Pollens produced in large number in wind pollinated plant species, float in the
air and enter human respiratory system – some people develop allergy to them
producing respiratory disorders like rhinitis, asthma and bronchitis.
Q. What is pollination ? Name different types of pollination.
Ans. Pollination -> it is the transfer of pollen grains from the anther to stigma .
Pollination is two types :
1. Self –pollination . It is also called autogamy. The pollen grains are transferred
on the stigma of the same flower.

11. 2. Cross-pollination . It is also called allogamy. If the transference
of pollen takes place in different flowers of same plant , it is
known as Geitonogamy. On the other hand , if cross-
pollination occurs among different flowers of different plants,
it is called the Xenogamy.
In cross-pollination , pollen grains of one flower are deposited
on stigma of another flower by various agencies like wind ,
water, insects, birds and animals

12. Q. What do you understand by double fertilization ?
Ans. Double fertilization -> in angiosperms both the male gametes are
functional. Double fertilization is a process in which egg nucleus and secondary
nucleus are fertilized at one time by the male gametic nuclei. The fusion of one
male gamete nucleus with egg or oosphere is called syngamy and result in the
formation of oospore . The second male gamete fuses with the secondary
nucleus it is called triple fusion which results in formation of primary endosperm
nucleus . It was first discovered by Nawaschin (1898).

13. Q. Give an account of significance of double
fertilization.
Ans. Significance of double fertilization .
(1) after double fertilization development of
endosperm starts when it is required by
developing embryo.
(2) It ensures that nutritive tissue is formed .
(3) Double fertilization provides the
characteristics of male plants as well the nutritive
tissue.

14. Q. What is bagging technique ? How is it useful in plant breeding pro-grammes ?
Ans. Bagging technique.
During artificial hybridization of plant breeding, to ensure cross-pollination , bagging
technique is involved.
Removal of anthers from the flower bud before the anther dehisces using a pair of
forceps is necessary. This step is referred to as emasculation . Covering of emasculated
flowers with a bag of suitable size, generally made up of butter paper, to prevent
contamination of its stigma with unwanted pollen. This process is called bagging.
Advantages of bagging technique
1. It is necessary for cross-breeding for crop improvement programme.
2. Commercially superior hybrid varieties can be obtained .

15. Q. What is meant by emasculation ? When and why a plant breeder employ
this technique?
Ans. Emasculation . Removal of anthers from the flower bud before it dehisces,
using a pair of forceps.
Emasculation is applied by plant breeders to carry out artificial hybridization ,
in order to carry out crossing experiment . It helps in producing
commercially superior varieties of plant.

16. Q. Compare the structure of a non-endospermic (non-albuminous)
seed with an endospermic (albuminous ) dicot seed.
Seed of Pea
(Non – endospermic Seed )
Seed of Castor
(Endospermic Seed )
1. The testa is soft and thin .
2. The endosperm is absent .
3. The cotyledons are thick .
4. The food is stored in the
cotyledons.
1. The testa is very hard and brittle
2. The endosperm is present .
3. The cotyledons are thin and
papery.
4. The food is stored inside the
endosperm.
Ex. Pea, Bean and Mustard. Ex. Rice, wheat , maize, castor .

17. Q. What are chasmogamous flowers ? Cam cross pollination occur in
cleistogamous flowers ? Give reassons for your answer.
Ans. (i) Chasmogamous flowers. These flowers are similar to flowers ot other
species with exposed anthers and stigma.
Ex. Viola (common pansy), Oxalis and Commelina.
(ii) Cleistogamous flower do not open at all. In such flowers anthers and stigma
lie close to each other. When anther dehisces in the flower the pollen grain
come in close contact with the stigma to affect self-pollination . Thus cross
pollination cannot take place.

18. Q. What is triple fusion? Where and how does it take place ? Name the nuclei
involved in triple fusion ?
Ans. Triple fusion . 1. it is the fusion of secondary nucleus of embryo sac with
one male gamete.
2. It occurs in embryo sac.
3. Nuclei involved are two polar nuclei and one nucleus of male gamete.

19. Q. What is self incompatibility ? Why
does self pollination not lead to
seed formation in self incompatible
species ?
Ans. In some plants self incompatibility
occurs i.e. pollen of a flower does
not germinate on the stigma of
same flower. This inhibition may be
mechanical or chemical. Even if the
pollen tube grows to some distance,
viable male gametes are not formed
and hence no fertilition . So , no
seeds are formed.
Q. What is pollen pistil interaction ?
Ans. Pollen pistil compatibility is
essential for a successful pollination
. If the pollination is not of right
type, the pollen is prevented from
germination . This interaction can
be both physical barriers and
chemicals.

20. Q. What are the various parts of a
seed ?
Ans. Seed coats : Testa and tegmen
Embryo : The future plant and consists of
radicle, plumule and cotyledon.
Endosperm : The food storing tissue. It may
be absent in some seeds. E.g. gram
seed.
Q. What is an embryo sac ?
Ans. It is the female gametophyte of
angiosperms. It develops form
the megaspore and is haploid. A
mature embryo sac is seven
called and eight nucleated
structure. It contains an egg
apparatus, antipodals and two
polar nuclei.

21. Q. How is pollination accomplished in Vallisneria?
Ans. It is a submerged hydrophyte. The female flower has a very long pedicel and
comes to the surface. Male flowers are released from the male plant and are free
floating Male and female flowers collide accidentally and pollination takes place.
After pollination, the female flower is thrown into coils and becomes submerged
again.

22. Q. How does the synergid helps in syngamy ?
Ans. The sygergids have a finger like structure called filiform apparatus. It
guides the pollen tube into itself. Through the synergid, the pollen tube
reaches the egg. One male cell and egg fuse to form zygote.
Q. What external conditions are needed by a seed to germinate?
Ans. The seed needs three external conditions to germinate
(i) Water: it hydrates the seed and makes the testa soft.
(i) Oxygen: Oxygen is taken through micropyle and also through the softened
testa.
(iii) Suitable temperature: A temperature of 25-30°C is suitable for metabolic
activities.
Q. What is external fertilization?
Ans. When the fusion of gametes occurs outside the body of the organism, it
is called external fertilization . Such zygotes are liable to be eaten by
predators.

23. Q. What is parthenocarpy? Can it be
induced artificially?
Ans. Formation of fruit without
fertilization is called parthenocarpy. Such
fruits are seedless can be induced
artificially by the application of gibberellins
hormone.
Q. What is apomixis? How can it be utilized
commercially?
Ans. Formation of fruit without fertilization
is called apomixis. Here, the embryo sac
develops without the process of meiosis,
from the cells of nucellus or that of
integument. Such embryo sacs have diploid
egg which develops parthenogenetically.

24. Long Answer Type Questions
Q. 2. With a neat labelled diagram, describe
the parts of a typical angiosperm ovule.
Or
Describe the structure of megasporangium.
Ans. Megasporangium . Ovule is an
integumented megasporangium. It develops
into seed after fertilization.
Structure of ovule -: Each ovule consists of
nucellus surrounded by two integuments and
a stalk or funiculus.
(i) Funiculus -> is stalk-like structure by which
ovule is attached to the placenta.
(ii) Hilum -> It is the point of attachment of
the body of the ovule with the funiculus.
(ii) Raphe -> It is the longitudinal ridge formed
by lengthwise fusion of funiculus with the
body of ovule in a typical anatropous ovule.

25. (iv) Nucellus-> It is a mass of diploid cell called megas-
porangium. It provides nourishment in the development
of embryo sac.
(v) Embryo sac -> It is the female gametophyte which
contains the egg apparatus, antipodal and polar nuclei.
(vi ) Integuments form seed coats i.e. testa and tegmen.
(vii) Micropyle ->It is small opening which is left by the
integument in the ovule for the passage of pollen tube
into the ovule .
(viii)Chalaza -> The basal region of ovule from where the
integuments arise called chalaza.

26. Q. Write a note on the development of endosperm. Mention the types with
examples.
Ans.
Development of endosperm. Endosperm develops after double fertilization in
angiosperms . It is triploid and develops from primary endosperm nucleus In
angiosperms three types of endosperm development are observed.
1. Nuclear endosperm -> In endosperm development nucleus divides by free
nuclear division, there is appearance of central vacuole, all the nuclei are pushed
towards periphery then starts cytokinesis and results into the formation of cells but
in coconut vacuole persists which is filled with fluid.

27. 2. Cellular endosperm -> In cellular endosperm each and every division is
followed by cytokinesis, so endosperm is cellular from the very beginning e.g.
Datura, Petunia.
3. Helobial endosperm. It is intermediate between cellular and nuclear
endosperm. The first division is followed by cytokinesis unequal cella,
micropylar cell and chalazal cell. Further divisions in each cell are free nuclear
divisions. This type of endosperm is found in order Helobiales.
Q. . Explain the development female gametophyte, Illustrate the answer with
suitable diagrams. Explain formation of embryo sac in plants .
Ans. Development of female gametophyte.
1. The functional megaspore is the first cell of female gemetophyte of
angiosperms.
2. It enlarges to form the female gametophyte, also called embryo sac.
3. Its nucleus undergoes a mitotic division and the two nuclei move to the
opposite poles, forming the 20nucleate embryo sac.
4. Two successive mitotic divisions in each of these two nuclei result in the
formation of an 8-nucleate embryo sac.
5. Cell wall formation starts at the eight nucleate stage, resulting in the
formation of typical female gametophyte.

28. 6. Three cells are grouped together at the micro-pylar end of form
the egg apparatus, consisting of two synergids and a female
gamete/ egg cell.
7. Three cells are grouped together at the chalazal end; they are
called antipodal cells.
8. The remaining two nuclei are called polar nuclei; they move to
the center of the embryo sac (now called central cell) and fuse to
form a diploid secondary nucleus.
9. Thus , a typical angiosperm embryo sac is 8-nucleate and 7-
called.

29. Q. Explain the germination of pollen grain with the help of a diagram.
OR
write about the structure and development of male gametophyte in
angiosperms.
Ans. Pollen grain is the first cell of male gametophyte. It has a single haploid
nucleus and some reserve food. It starts developing while still inside the anther.
Its nucleus divides into two and two asymmetrical cells are formed . The smaller
is called a generative cell and the larger is called the vegetative cell.

30. Gradually, the generative cell becomes spearate form
the vegetative cell and becomes free floating in the
vegetative cell. It is at this stage that pollination occurs
and the pollen is carried to the stigma.
On landing on a suitable stigma, it germinates by giving
out a pollen tube through one of its germ pores . the
pollen tube grows through the tissues of stigma and
style and reaches the ovary. The generative cell in the
pollen tube divides into two male gametes. The pollen
tube enters the ovule and discharge its both the male
cells in the cavity of embryo sac. So, it is the three called
male gametophyte.

31. Multiple Choice Question
1. Egg apparatus occurs on the.
(a) Chalazal end of embryo sac
(b) Micropylar end of embryo sac
(c) Middle of embryo sac
(d) Outside the embryo sac
Ans. (b) Micropylar end of embryo sac
2. Formation of 2n embryo sac from the cells of nucellus is called.
(a) Apomixis
(c) Apogamy
(b) Apospory
(d) Polyembryony
Ans. (a) Apomixis

32. 3. In an angiosperm, the male plant is diploid and the female plant is tetraploid.
The endosperm will be.
(a) Haploid
(b) Diploid
(c) Triploid
(d) Pentaploid
Ans. (d) Pentaploid
4. Pollination occurs by wind in
(a) Sunflower
(c) Maize
(b) Salvia
(d) Castor
Ans. (c) Maize
5. Cleistogamy occurs in
(a) Allium cepa
(b) Oryza sativa
(c) Commelina
(d) Delphinium
Ans. (c) Commelina

33. 6. When pollen of a flower is transferred to the stigma of another flower on the same
plant, this is called
(a) Geitonogamy
(b) Xenogamy
(c) Autogamy
(d) Allogamy
Ans. (a) Geitonogamy
7. Development of fruit without fertilization is called .
(a) Partenocarpy
(b) Pseudocarpy
(c) Apospory
(d) Adventive embryony
Ans. (a) Parthenocarpy
8. Exine of the pollen is made up of
(a) Pectin
(b) Cutin
(c) Sporopollenin
(d) Cellulose
Ans. (c) Sporopollenin

34. 9. Which of the following is not a part of the embryo
(a) Radicle
(6) Plumule
(c) Cotyledons
(d) Integuments
Ans. (d) Integuments
10. Megaspore mother cell undergoes meiosis to form
(a) One megaspore
(b) Two megaspores
(c) Three megaspores
(d) Four megaspores
Ans. (d) Four megaspores
11. Cells of the nucellus are
(a) Haploid
(c) Triploid
(b) Diploid
(d) Polyploid
Ans. (b) Diploid

35. 12. Which among the following is diploid
(a) Tube nucleus
(b) Egg
(c) Antipodals
(d) Zygote
Ans. (d) Zygote
13. Male gametophyte has
(a) One cell
(b) Two cells
(d) Many cells
(c) Three cells
Ans. (c) Three cells
14. Salvia is pollinated by
(a) Insects
(b) Wind
(c) Water
(d) Bats
Ans. (a) Insects

36. 15. Coconut has a ………. type of endosperms
(a) Cellular
(b) Hollow
(c) Nuclear
(d) Helobial
Ans. (c) Nuclear
16. Which of the following is an endospermit seed?
(a) Pea
(b) Castor
(c) Gram
(d) Bean
Ans. (b) Castor
17. Which of the following is also called megasporangium
(a) Carpel
(b) Anther
(c) Ovule
(d) Embryo sac
Ans. (d) Embryo sac

37. 18. Which of the following is not a wall layer of anther
(a) Epidermis
(c) Tapetum
(b) Endothecium
(d) Nucellus
Ans. (d) Nucellus
19. When the pollen tube enters the ovule through the micropyle, it is called
(a) Porogamy
(b) Chalazogamy
(c) Siphonogamy
(d) Mesogamy
Ans. (a) Porogamy
20. Occurence of more than one embryo in a seed is called
(a) Polyembryony
(b) Apomixis
(c) Polyploidy
(d) Parthenocarpy
Ans . (a) Polyembryony

38. 21. Bright coloured flowers and scent is an adaptation for pollination by
(a) Wind
(b) Insects
(c) Water
(d) Bats
Ans. (b) Insects
22. In monocotyledonous seeds, the endosperm is separated from the
scutellum by
(a) Epidermis
(b) Epithelial layer
( c) Aleurone layer
(d) Coleorhiza
Ans. (b) Epithelial layer
Ans. 23. Which of the following is not essential for the germination of seeds.
(a) Wind
(b) Water
(c) Fertilizer
(d) Suitable temperature
Ans. (c) Fertilizer

39. 24. Cross pollination is preferred over self pollination because
(a) It is easy.
(b) It produces beautiful flowers.
(c) Parthenogenesis can be induced.
(d) It produces better progeny.
Ans. (d) It produces better progeny
25. Filiform bodies occur in
(a) Egg
(b) Synergids
(c) Antipodals
(d) Endosperm
Ans. (b) Synergids
26. Flowers having bright colours, fragrance and nectar are suited for which
type of pollination?
(a) Entomophily
(b) Ornithophily
(c) Hydrophily
(d) Anemophily
Ans. (a) Entomophily

40. 27. In which of the following polyembryony is found?
(a) Guava
(b) Orange
(c) Gram
(d) Maize
Ans. Orange
28. Which of the following are water pollinated?
(a) Vallisneria and Hydrilla
(b) Vallisneria and Water hyacinth
(c) Vallisneria and Oxalis
(d) All of these
Ans . (a) Vallisneria and Hydrilla
29. In angiosperms, a mature embryo sac is
(a) 8 celled and 8 nucleated
(b) 7 celled and 8 nucleated
(c) 7 celled eight nucleated
(d) 8 celled 7 nucleated
Ans. (b) 7 celled and 8 nucleated

41. 30. One ovule is present in an ovary of
(a) Wheat
(b) paddy
(c) Both a and b
(d) Papaya
Ans. (c) Both a and b
31. Many ovules are of present in the ovaries
(a) Papaya
(b) Water melon
(c) Orchids
(d) All of these
Ans. (d) All of these
32. Which of the following animals may be agent of pollination.
(a) Sunbird
(b) Bat
(c) Humming bird
(d) All of these
Ans. (d) All of these