0CUSED SNOILS

AS PER
NEP MultipleChoice Questions

the following questions.

Chonse and write the correct option(s) inconsists
bilobed anther of [CBSE Sample Ouestion Paper 2022, Term-1|
1. The structure of (b) 4 thecae, 4 sporangia
(a) 2 thecae, 2 sporangia
(c) 4 thecae, 4 sporangia (d) 2 thecae, 4 sporangia
hypogynous flower the arrangement of floral whorls om
9 In a typical complete, bisexual and innermost is [NCERT Exemplar]
the
thethalamus from the outermost to
gynoecium
(a) calyx, corolla, androecium and
androecium
(b) calyX,corolla, gynoecium and
corollaand calvx
(c) gvnoecium, androecium,
calyx
(d) androecium, gynoecium, corolla and
produces fruits and seeds. The most probable
8. Adicotyledonous plant bears flowers but never [NCERT Exemplar]
cause for the above situation is
flowers.
(a) plant is dioecious and bears only pistillate
staminate flowers.
(b) plant is dioecious and bears both pistillate and
(c) plant is monoecious.
flowers.
(d) plant is dioecious and bears only staminate
dormancy are TRUE?
4. Which of these statements about seed
1. Seeds do not respire during dormancy.
2.Seeds lose a lot of water before dormancy.
3. Seeds have low metabolic rate during dormancy. [CBSE Question Bank]
4. Seeds have no metabolicactivity during dormancy.
(a) only l and 3
(b) only 2 and 3
(c) only l and 4 (d) only 1, 2 and 3
occurs in [NCERT Exemplar]
5. During microsporogenesis, meiosis (b) microspore mother cells
(a) endothecium
(c) microspore tetrads (d) pollen grains.
the
below, identify those that are associated with
6. From among the sets of terms given [NCERT Exemplar]
8ynoecium.
(a) Stigma, ovule, embryosac, placenta (b) Thalamus, pistil, style, ovule
(c) Ovule, ovary, embryo sac, tapetum (d) Ovule, stamen, ovary, embryo sac
I. Starting from the innermost part, the correct sequence
of parts in an ovule are
[NCERT Exemplar]
sac, ucellus, integument
(a) egg, nucellus, embryo sac, integument (b) egg, embryo
embryo sac, nucellus
(c) embryo sac, nucellus, integument, egg () egg, ntegument,
that are true for a typical female
Þ. From the statements given below choose the option
gametophyte of a flowering plant.
) It is 8-nucleate and 7-celled at maturity.
(ii) It is free-nuclear during the development.
(ii) It is situated inside the integument but outside the nucellus. [NCERT Exemplar]
(0) It has an egg apparatus situated at the chalazal end. (d) (i) and (iv)
(a) (i) and (iv) (b)(i) and (ii) (c) ()and (i)

Plants 25
Sexual Reproduction in Flowering
 9. Autogamy can occur in a chasmogamous flower if
[NCERT Exemplar|
(a) pollen matures before maturity of ovule.
(b) ovules mature before maturity of pollen.
() both pollen and ovules mature simultaneously.
(d) both anther and stigma ae of equal lengths.
lobes, theca and sporangia. The theca are
10. An anther is nade up of the following major parts:
cavities in which the sporangia develop.
develop into a tetrasporangiate anther?
Which of the following types of anther structure can |CBSE Question Bank|
(b) monothecous
(a) filamentous
(d) unlobed
(c) dithecous
following. [NCERT Exemplar
11. Choose the correct statement from the
autogamy.
(a) Cleistogamous flowers always exhibit
() Chasmogamous flowers always exhibit geitonogamy.
geitonogamy.
(c) Cleistogamous flowers exhibit both autogamy and
(d) Chasmogamous flowers never exhibit autogamy.
12. Which of the following structures are haploid in nature?
(a) Nucellus and antipodals (b) Microspore and antipodals
(c) Egg cell and antipodals (d) Egg and central cell
13. In a fertilized ovule, n, 2n and 3n conditions occur respectively in
[CBSE Sample Question Paper 2022, Term-I]
(a) antipodal, zygote and endosperm (b) zygote, nucellus and endosperm
(c) endosperm, nucellus and zygote. (d) antipodals, synergids and integuments
[CBSE 2020 (57/1/)]
14. Self-pollination is fully ensured if
(a) the flower is bisexual (b) the style is longer than the filament
(c) the flower is cleistogarmous (d) the time of pistil and anther maturity is different
pollen in large numbers and its stigmas
15. Aparticular species of plantproduces light, non-stickypollination by [NCERT Exemplar
are long and feathery. These modifications facilitate
(a) insects (b) water

(c) wind (d) animals.

both autogamy and
16. From among the situations given below, choose the one that prevents [NCERT Exemplar)
geitonogamy.
(a) Monoecious plant bearing unisexual flowers
(6) Dioecious plant bearing only male or female flowers
(c) Monoecious plant with bisexual flowers
(d) Dioecious plant with bisexual flowers
17. In afertilised embryo sac, the haploid, diploid and triploid structures are [NCERT Exemplar|
(a) synergid, zygote and primary endosperm nucleus.
(b) synergid, antipodal and polar nuclei.
(c) antipodal, synergid and primary endosperm nuceus.
(d) synergid, polar nucdei and zygote.
18. In an embryo sac, the cells that degenerate after fertilisation are
[NCERT Exemplar]
(a) synergids and primary endosperm cell (b) synergids and antipodals
(c) antipodals and primary endosperm cell (d) egg and antipodals.
19. Which of the following seeds have remained alive for the longest period? (CBSE 2023 (57/3/1)
(a) Phoenix dactvlifera (b) Striga asiatica
(c) Mangifera indica (d) Yiucca gigantea
20. While planning for an artificial hybridisation programme involving dioecious plants, which
of the following steps would not be relevant? [NCERT Exemplar]
(a) Bagging of female flower (b) Dusting of pollen on stigma
(c) Emasculation (d) Collection of pollen
21. Amongst the insects the dominant biotic pollinating agents are [CBSE 2021 Term-1,(57/2/4)1|
(a) Ants (6) Wasps
(c) Beetles (d) Bees
22. Choose the option that gives the correct number of pollen grains that will be formed after 325
microspore mother cells undergo microsporogenesis. [CBSE 2023 (57/1/1)]
(a) 325 (b) 650
(c) 1300 (d) 975
23. In the embryos of a typical dicot and a grass, true homologous structures are
[NCERT Exemplar]
(a) coleorrhiza and coleoptile (6) coleoptile and scutellum
(c) cotyledons and scutellum (d) hypocotyl and radicle.
24. The phenomenon observed in some plants wherein parts of the sexual apparatus is used for
forming embryos without fertilisation is called [NCERT Exemplar]
(a) parthenocarpy (b) apomixis
(c) vegetative propagation (d) sexual reproduction.
25. In aflower, if the megaspore mother cell forms megaspores without undergoing meiosis and
if one of the megaspores develops into an embryo sac, its nuclei would be [NCERT Exemplar]
(a) haploid (6) diploid
(c) a few haploid and a few diploid (d) with varying ploidy.
26. The figures of the development stage of a microspore into a mature pollen grain are given
below. Choose the option showing the correct labellings for (i), (ii), (iii) and (iv).

() (i)

(i) (ii).

(1) (i) (iii) (iv)

(a) Generative cell Vegetative cell Male gamete Vacuole

(b) Vegetative cell Generative cell Vacuole Male gamete

(c) Vegetative cell Generative cell Nucleus Vacuole

(d) Generative cell Vegetative cell Vacuole Nucleus

Sexual Reproduction in Flowering Plants 27

 27. Enlisted are some events during fruit formation.
1.The egg cell is fertilised by a male gamete.
2. The thalamus withers away.
3. The ovules form seeds.
4. The ovary develops into the fleshy fruit.
Which of these events is/are NOT TRUE for an apple fruit?
(a) only 1
(c) only 2 and 4
(b) only 2
(d) only 2, 3 and 4
[CBSE Quen,
28. Why is the endosperm in flowering plants 3n?
(a) because it is formed from 3
antipodal cells.
(b) because it is formed from 2 male
[CBSE Queih,
gametes and an egg cell.
(c) because it is formed from 2 male
gametes and a polar nucleus.
(d) because it is formed from l
29. The coconut water
male gamete and 2 polar nuclei.
rom tender coconut is
(a) cellular endosperm
(c) both cellular and (b) free nuclear endosperm
30. Pollen grains are well
nuclear
endosperm (d) free nuclear embryo
preserved as
(a) sporopollenin (b) cellulose fossils because of presence of
31. Which of the (c) lignocellulose (d) pectocellulose
following statements are true related to seed X
and Y?

SEED X
SEED Y
(i) SeedX is dicot and
(ii) Seed X is dicot and endospermic or albuminous.
(ii) Seed is monocot and non-endospermic non-albuminous.
or
(iv) Seed Y is monocot and endospermic albuminous.
or
non-endospermic non-albuminous.
Choose the correct option with respect to the
or
(a) (i), (i) nature of the seed.
(b) (i), (üi) (c) (), (v)
32. A botanist studying Viola (d) (ü), (iv)
(common
and developed no further due to some pansy) noticed that one of the two flower types wither
unfavorable
the same plant survived and it resulted in an condition, but the other flower type
correct?
assured seed set. Which of the following will b
(a) The flower type which survived is
(b) The flower type which survived is cleistogamous
and it always exhibits autogamy.
chasmogamous and it alwaysexhibits geitonogamy.
28 Xam idea Biology-XIl
 c) The flower type which survived is cleistogamous and it exhibits both autogamy and
geitonogamy.
(d) The flower type which survived is chas1mogamous and it never exhibits autooamy

33. To produce 400 seeds, the number of meiotic divisions required will be
(b) 200 (c) 500 (d) 800
(a) 400
34. Select the plant species, where emasculation is not required for artificial hybridisation
experiment?
(a) Castor (6) Lily (c) Papaya (d) Wheat
35. Which of the given statements are correct with respect to pollination in Vallisneria?
(i) Pollen grains are light and non-sticky.
(ii) Female flowers reach the surface of water by long stalks.
(iü) Pollen grainsare carried passively by water currents.
(iv) Female flowers remain submerged in water.
Choose the correct option:
(a) (i) and (v) (b) (i) and (iv)
(c) ()and () (d) (ii) and (ü)
Answers
1. (d) 2. (a) 3. (d) 4. (b) 5. (b) 6. (a) 7. (b) 8. (c) 9. (c) 10. (c)
11. (a) 12. (c) 13. (a) 14. (c) 15. (c) 16. (b) 17.(a) 18. (b) 19. (a) 20. (c)
21. (d) 22. (c) 23. (c) 24. (b) 25. (b) 26. (c) 27. (b) 28. (d) 29. (b) 30. (a)
31. (b) 32. (a) 33.(c) 34. (c) 35. (d)
CUSED
SONS
AS PER

NEP Assertion-Reason Questions

In the following questions astatement of assertion followed by a statement of reason is given. Choose
the correct answer out of the following choices.
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statenents but reason is not correct explanation for assertion.
(c) Assertionis correct statement but reason is wrong statement.
(d) Assertion is uurong statement but reason is correct statement.
1. Assertion : The endosperm of angiosperms is generally triploid (3n).
Reason It develops from primary endosperm nucleus formed by fusion of haploid male
gamete and diploid secondary nucleus.
2. Assertion : Dichogamy refers to maturation of male and female sex organs at different times.
Reason This is a safeguard against cross fertilisation.
3. Assertion :
Megaspore mother cell undergoes meiosis to produce four megaspores.
Reason Megaspore mother celland megaspores are both haploid.
4. Assertion : Entomophilous plants produce less pollen when compared to anemophilous plants.
Reason The wastage of pollen is reduced to the minimum in entomophilousplants because
of the directional pollination.
5. Assertion :
A structure of a typical microsporangium in angiosperms consists of four wall
layers-epidermis, endothecium, middlelayers and tapetunm.
Reason Thefunction of outer three wall layers is protectionand also help in dehiscence of
anther to release pollen.

Sexual Reproduction in Flowering Plants 29

 6. Assertion : A pollen grain can withstand harsh conditions.
Reason The exine of pollen grains is made up of sporopollenin which is
temperatures, strong acids or alkali as well as
7 Assertion :
enzymatic
Inplants, apomixis is atype ofasexual reproductionthat
midegr
mics asexual
dation. resisant
Reason In apomixis seeds are produced
8. Assertion : In coconut, the water represents the free
without the fusion of gametes
nuclear endosperm and reprodu
representsthe cellular endosperm. thhe white ker
Reason PEN undergoes a number of free nuclear divisions which are
9. Assertion :
formation.
In monosporic type of embryo development, megaspore is
followed
situated
Reason
micropylar end and remains functional.
In monosporic development the embryo sac towards
develops from a single funt
10. Assertion :
megaspore.
Reason
Microspore is the first cell of male gamnetophyte.
It is
diploid nature.
in
11. Assertion:
Apomictic fruits are seedless.
Reason Apomictic fruits are formed without fertilisation.
12. Assertion :
Endosperm is completely consumed during, the development [CBSE Question Ban
albuminous seeds. of embrvo in.
Reason Castor, pea and beans are all examples of
ex-albuminous seeds.
Answers [CBSE 2023 (57/1
1. (a) 2. (c) 3. (c) 4. (b) 5. (b) 6. (a) 7. (a)
11. (d) 12. (c) 8. (c) 9.(b) 10. (o
GUSEDQUE
TION
AS PER
NEP
Passage-based/Case-based/
Source-based Questions
Read the given passages and answer the
questions that follow.

Observe the figure of fertilised embryo sac of an

PASSAGE-1
angiosperm and answer the questions that follow.
Degenerating
synergids
-Zygote (2 n)
Primary endosperm
cell (PEC)
Primary endosperm
nucleus (3n)
(PEN)

-Degenerating
antipodal cells

30 Xam idea Biology-XIl

 0.28. What is nucellus?
AnS. The body of the ovule consists of a mass of parenchymatous cells rich in reserve food material
which is called nucellus.

o 29. Namethe common function that cotyledons and nucellus perform. [NCERT Exemplar]
Ans. Cotyledons and nucellus provide nourishment.
20 Which are the three cells found in a pollen grain when it is shed at the three-celled stage?
[NCERT Exemplar]
Ans. One vegetative cell and two male gametes.
0.3 What features of flowers facilitate pollination by birds?
Ans. Presence of a large quantity of nectar, bright colours of petal, fragrance and large flowers attract
birds from long distances.
0.32,Näme the type of pollination in self-incompatible plants. [NCERT Exemplar]
Ans. Xenogamy.
o.35. Mention any two characteristics of pollen grains of plants such as maize and Cannabis.
Ans. () Pollen grains are small, dry and light in weight, non-sticky.
() Pollen are produced in large numbers.
Q.34. Define parthenocarpy.
Ans. Parthenocarpy is an economically important process in which seedless fruit is formed without
fertilisation, for example, banana.
0.35. In a case of polyembryony, if an embryo develops from the synergid and another from the
nucellus, which is haploid and which is diploid? [NCERT Exemplarl
Ans. Synergid embryo is haploid and nucellar embryo is diploid.
SPONSE
TIONS
AS PER

NEP Short Answer Questions

SNO
Each of the following questions are of 2 marks.
Q.1. In a flowering plant a microspore mother cell produces four male gametophytes while a
megaspore mother cell forms only one female gametophyte. Explain. [CBSE Delhi 2017]
Ans. Male gametophytes are formed by meiosis of single microspore mother cell whereas female
gametophytes are formed by meiosis of single megaspore mother cell to produce four megaspores,
out of which three degenerate and only one survives. The surviving megaspore undergoes mitotic
division to form the female gametophyte.
Q. 2. In the T.S. of a mature anther given below,identify "a" and "b" and mention their function.

Ans. a-Sporogenous tissue: It forms pollen grains.

b-Tapetum: It provides nourishment to the developing pollen grains.

Sexual Reproduction in Flowering Plants 35

 Q.3. Name the organic materials the exine and intine of an angiosperm
of. Explain the role of exine. pollen grains are ma
Ans. Exine is made up of sporopollenin and intine is made up of cellulose and
exine is the most resistant organic material and can withstandIhigh pectin. (CBSE Del
environment.
Q. 4. Differentiate between the two cells enclosed in a mature male
S poro pailk
temperatugraem,aectoipdhiyctean,
angiosperm.
Ans. Table 1.7: Differences between vegetative and generative cell of pollen . CBSE (A
S.No. Vegetative cell
() It is bigger in size.
Generative cell
It is smaller and floats
in the cyopl
vegetative cell.
() It has food reseTves. It gives rise to twO male gametes
Q.5. "Pollen grains in wheat are shed at 3-celled stage while in peas
they are shed at 2-celled.
Explain. Where are germ pores present in a pollen grain?
Ans. (CBSE (Al:
plant incadng hole.
shed at cled stage. The
cel md egetatve cel

at

Te 2 mae netesy

on the
exme
absent
[Topper's Answer2
Q. 6. Gynoecium of a flower may be apocarpous or syncarpous. Explain with the help of an exa
each.
[CBSE (AI))
Ans. The gynoecium represents the female reproductive part of the flower. When there are more
one pistil,if the pistils are fused together, the flower is said to be syncarpous and if the pisti
free, it is said to be apocarpous. For example, pistil of Papaver is syncarpous and that ot Ma
is apocarpous.
Q.7. Name all the haploid cells present in an unfertilised mature embryo sac of a flowering p
Write the total number of cells in it. [CBSE (A)2
Ans. The haploid cells in an unfertilised mature embryo sac are: egg cell,
synergids, antipodas
central cell. There are seven cells in total.
Q. 8. Draw a diagram of pollen grain with germ tube and two male gametes.
Ans.
Exine Intine
Male
gametes
Tube
nucleus

Pollen tube
 o9. Why does the zygote begin to divide only after the division of primaryendosperm cell?
INCERT Exemplar]
The zvgote needs nourishment during its development. As the mature, fertilised embrvo sac
Ans.
and
offers very little nourishment to the zygote, the primary endosperm cell (PEC) divides
zygote. Hence, the zygote always divides
generates the endosperm tissue which nourishes the
after divisionof PEC.
entry into the embrvO
o10. (a) From which end of theovule, and how does the pollen tube gain its
sacof a Hibiscus flower?
pollen tube. [CBSE 2023 (57/1/1)]
(b) State the fate of the male nuclei present in the
the region of the
Ans. (a) The pollen tube enters the embryo sac between the two synergids through
filiform apparatus at the micropylar end of the ovule.
cell called zygote and
(b) One of the male gamete fuses with egg nucleus to form adiploid
the other male gamete fuses with polar nuclei at the centre to produce a triploid primary
endosperm nucleus.
0. 11. Which is the triploid tissue in a fertilised
ovule? How is the triploid condition achieved?
[NCERT Exemplar]
triploid condition is achieved by the fusion
Ans. The triploid tissue in the ovule isthe endosperm. Its triple fusion.
referred to as
of two polar nuclei and one nucleus of male gamete,
function.
0. 12. Fill in the following labels with the type of cell
B D
A

Nuclei Female gametophyte

DCells reorganised as
Ans. X-Meiosis (Reduction division); AMitosis; B-Mitosis;C-Mitosis;
polar nuclei, antipodals and egg apparatus.
female gametophyte of an
0. 13. Mention the ploidy of the different types of cells present in the [CBSE Delhi 2017]
angiosperm.
Ans.
Table 1.8: Ploidy of cells in female gametophyte
Cells in female gametophyte Their ploidy
1. Synergids Haploid
2. Egg Haploid
3. Polar nuclei Haploid
4. Antipodals Haploid
5. Central cell 2 haploid nuclei
Q. 14. Write briefly the role of pollination in the growth and development in an angiosperm.
Ans. Pollination is transfer of pollen grains from anthers to the stigma of a flower. Pollination is
prerequisite for fertilisation, events after fertilisation like endosperm development, seed setting
and fruit formation. Thus, pollination plays an important role in the growth and development ot
angiosperms.
Q. 15. Explain any two devices by which autogamy is prevented in flowering plants.
Ans. (i) Male and female flowers are present on different plants.
(ii) The stamens and stigma of a bisexual flower mature at different times.
(a) Anthers mature earlier than the stigma and release pollens.
(b) The stigma matures earlier than the anther.
(ii) Flowers are self-sterile or self-incompatible.
(iv) Chasmogamous flowers are present with exposed stamens and stigma which facilitate crosS
pollination. (Any two)

Sexual Reproduction in Flowering Plants 37

 Q. 16. What is cleistogamy? Write one advantage and one disadvantage of it, to
the plant.
Ans. Pollination occurring in closed flowers. CBSE 2019 (5%
Advantage:Ensures self pollination/ Assured seed set formation in absence
of
Disadvantage : does not alloW eross pollination / genetic variation l
depression. can pol inatr s
cause inbreo
(CBSE Marking Scheme 2019 (52%.
Q.17. (a) List any two characteristic features of
pollination.
wheat flowers that make it a good example at
(b) It is observed that plant breeders
carrying out wheat hybridisation often take pollen ox
from the 'pollen banks'. Do you agree ? Give one reason in support of
your answer
Ans. (a) Light pollen grains/pollen grains more in [CBSE 2019 (573:
single ovule/numerous flowers packed into an number / exposed stamen / feathery stie
(b) " Yes. inflorescence. (Any two)
Viability of wheat pollen grain is only 30 minutes and so it
for a long period of time. can be stored in pollen b

[CBSE Marking Scheme 2019 (57131

Q. 18. List the twosteps that are
why. essential for carrying out artificial hybridisation in crop plants
Ans. (a) Selection of parents: Only [CBSE (F) 201.
those plants should be selected which have
Emasculation: Removal of anthers from flower before they are desired traits.
(b) Crossing over: Pollen grains from mature and dehisce.
female plant after which it is bagged.selected male plant is collected and transferred to
Q. 19. Explain the steps that
Ans. Abisexual flower is ensure crossat pollination in an autogamous flower. [CBSE Delhi 201
is bagged after emasculatedto unopened stage to prevent self-pollination in the flower
emasculation prevent contact of unwanted pollen grain with the
the flower. Artificial
rebagged.
pollination is then performed when the stigma is ready and stigma
the flower
Q.20. Geitonogamous flowering plants are
Justify.Give similarity of geitonogamy genetically autogamous but functionally cross-pollinat:
Ans. Geitonogamous flowers are with autogamy andxenogamy. [CBSE Delhi 201
borne on the same plant. They aregenetically autogamous because both male and female flowers
flower is transferred to the stigma of afunctionally cross-pollinated because the pollen from o
different flower.
Q. 21. Howdoes the
Ans. The petals of the Mediterranean orchid Ophrys ensures its pollination by bees? [CBSE Dellhi 201
Ophrys resemble the
mistakes the Ophrys for femalebee andfemale tries to
of a bee species in size, colour and
odour. Male
the male bee fall over stigma of the flower copulate. Few pollen grains adhered to the body
thereby leading to pollination
Q. 22. Why should a bisexual
flower be emasculated and bagged prior to showing sexual dee
artificial pollination?
Ans. A bisexual flower is emasculated to [CBSE (F) 201
prevent self-pollination in the flower and it is bagged att
emasculation to prevent contact of unwanted pollen grain with the
Q.23. Write the cellular contents carried by stigma of the flower.
into the embryo sac?
the pollen tube. Howdoes the pollen tube gain its e
Ans. Pollen tube carries two male gametes. [CBSE (F) 201
Pollen tube, after reaching the ovary, enters the ovule
through the micropyle and
the synergids through the filiform apparatus which guides the entry of pollen tubethenintoenters
egg e
38 Xam idea Biology-XII
 0.24. A pollen grain in angiosperm at the time of dehiscence from an anther could be 2-celled or
3-celled. Explain. How are the cells placed within the pollen grain when shed at a 2-celled
stage? [CBSE (AI) 2017|
In 2-celled stage the mature pollen grain contains one generative and vegetative cells, whereas in
Ans.
3-celled stage one vegetative celland two male gametes are present.
The generative cell being small floats in the cytoplasm of the vegetative cell. The pollen grains are
shed at this 2-celled stage.
0. 25. State one advantage and one disadvantage of cleistogamy.
[CBSE (AI) 2012]
Ans. Advantage: Self-pollination is assured/Seed production is assured.
Disadvantage: Least variations observed/Leads to inbreeding depression.
the kernel differ
0. 26. Name the product of fertilisation that forms the kernel of coconut. How does
from coconut water? [CBSE (E) 2012]
Ans. Endosperm forms the kernelof coconut.
The coconut water is free-nuclear endosperm whereas kernel is cellular endosperm.
[CBSE Delhi 2014]
0. 27. List the post-fertilisation events in angiosperms.
Ans. () Development of endosperm
(i) Embryogeny/development of embryo
(iii) Seed formation
(io) Fruit formation
Q.28. Mention the function of each of the following:
(a) Tassels of corn cob.
(6) Tapetum in the microsporangium. [CBSE (F) 2012]
Ans. (a) These are the stigma and style which wave in the wind to trap pollen grains.
(b) Provides nourishment to the developing pollen grains.
0. 29. Describe the development of endosperm after double fertilization in an angiosperm. Why
does endosperm development preceeds that of zygote? [CBSE Delhi 2015]
Ans. Refer to Points to remember 9 (Endosperm Development).
Cells of the endosperm provide nutrition to the developing embryo.
Q.30. Draw a vertical section of amaize grain and label (i) pericarp, (ii) scutellum, (ii)coleoptile and
(iv) radicle. [CBSE 2019 (57/5/1)]
Ans. Refer to Fig. 1.15(d).
Q.31. Explain the function of each of the following:
(a) Coleorrhiza
(b) Germ pores [CBSE (AI) 2012]
Ans. (a) Coleorrhiza protects the radical of (monocot) embryo.
(b) Germ pores allow germination of pollen grain and formation of pollen tubes.
Q. 32. Differentiate between albuminous and non-albuminous seeds, giving one example of each.
|CBSE Delhi 2011]l
Ans. Albuminous seeds have residual endosperm in them. For example, maize.
Non-albuminous seeds do not have any residual endosperm. For example, pea.
Q.33. In angiosperms, zygote is diploid while primary endosperm cell is triploid. Explain.
[CBSE Delhi 2010, (AI) 2013)
Ans. Azygote is formed by the fusion of haploid male gamete with the haploid egg to form adiploid
cell; whereas, primary endosperm nucleus (PEN) is formed by thefusion of haploid male gamete
with two haploid polar nuclei, forming a triploid nucleus.
Sexual Reproduction in Flowering Plants 39
 Q. 34. Some angiosperm seeds are said to be 'albuminous', whereas few ot
perisperm. Explain each with the help of an example. others are said
Ans. Albuminous seeds are those which retain a part of endosperm as it is
not CRSE (F%
during embryo development. For example, in wheat and maize. In Some
nucellus are also persistent. This residual, persistent nucleus is the
black pepper and beet.
Seeds
perisperm.
complForeterleymnar
Q. 35. Double fertilisation is reported in plants of both,
castor and groundnut.
exarno
mature seeds of groundnut are non-albuminous and castor are albuminous.
fertilisation events that are responsible for it.
Ans. The development of endosperm (preceding the embryo) takes place the
from primary en h'
[CBSE Del ExplHoaiwneve,
nucleus (PEN) in both, castor and groundnut.
The developing embryo derives nutrition from endosperm.
PEN undergoes repeated division to give free
nuclei. Subsequently cell wall is forme
endosperm becomes cellular. At this stage endosperm is
but in groundnut endosperm is consumed by growing retained in castor or isnot fully com
Q. 36. (a) You are embryo.
given castor and bean seeds. Which one of the two
would you select to obsem.
endosperm?
(6) The development of endosperm precedes that of
embryo in plants. Justify.
Ans. (a) Castor
[CBSE 2019 (671
(b) Endosperm stores reserve food materials / provides nutrition to the
developing embrv
[CBSE Marking Scheme 2019 (57
Q.37. (a) Mature seeds of legumes are
non-albuminous. Then, can it be assumed that dou
fertilisation does not occur in legumes?
(b) List the differences between the Explain your answer.
embryos of dicot (pea) and monocot (grass fam
Ans. (a) No it cannot be assumed so [CBSE (AI) 2
because fertilisation does takes place but the
consumed during embryo endosper
(b)
development.
Table 1.9: Differences between dicot and
S. No.
monocot embryo
Dicot embryo Monocot embryo
It has two cotyledons. It has one cotyledon.
(ii) Radicle and plumule are not covered with Radicle is
sheath. covered with coleorrhiza
plumule is covered by coleoptile.
Q.38. Draw a sectional view of an apple and label the
from an ovary. Then why is apple referred to as different parts of an ovary in it. Fruits deve
a false fruit?
Ans. Refer to Fig. 1.16(@). [CBSE () 2013, 20
In apple, the thalamus also contributes to fruit
formation. Therefore, it is called a false fruit.
Q. 39. What is pericarp? Mention its functions.
Ans. The wall of the ovary that develops into wallof the
fruit is called pericarp.
Functions: (i) Protects the seed till its
maturity.
(ii) Helps in seed dispersal.
Q.40. A non-biology person is quite shocked to know
and banana is a seedless fruit. Asa biology student that apple is a false fruit, mango is a true fr
how would you satisfy this person'
[CBSE Delhi 201
Ans. In apple only the thalamus (along with ovary) contributes to fruit
false fruit. Mango develops only from the fertilised ovary, formation. Therefore, ItH
therefore, it is a true fruit.
Bananadevelops from ovary but without fertilisation. The method is known as
Since there is no fertilisation, no seeds are formed in banana. parthenoca

40 Xam idea Biology-XI

 Q.41. Why are some seeds referred to as apomictic seeds? Mention one advantage and one
disadvantage to afarmer who uses them. [CBSE (A) 2015; (F) 2015]
Ans. Seeds that are produced withoutfertilisation are referred toas apomictic.
Advantage: Desired characters are retained in offspring (progeny) as there is no segregation of
characters in offspring (progeny). Seed production is assured even in absence of pollinators.
Apomicticseedsare economical as they can be used to grow crops year after year.
Disadvantage: Cannot controlaccumulation of deleterious genetic mutation. These are usually
restricted to narrow ecological niches and lack ability to adapt to changing environment.
0.42. Explain any two ways by which apomictic seeds get developed. [CBSE (E) 2013]
Ans. Ways by which apomictic seeds develop are:
i) Adiploid egg is formed without reduction divisionwhich develops into embryo without
fertilisation.
(ii) Some cells of the nucellus, which are diploid in nature, start dividing and without fertilisation
develop into embryo.
o. 43. If you squeeze aseed of orange you might observe many embryos of different sizes? How is it
possible? Explain. [CBSE (AI) 2010, Delhi2011)
Ans. In orange, the nucelar cells surrounding the embryo sac start dividing, protrude into the embryo
sac and develop into a number of embryos of different sizes.
0.4. Banana is aparthenocarpic fruit whereas oranges show polyembryony. How are they different
from each other with respect to seeds?
Ans. Banana develops from an ovary without fertilisation having no seeds so it is called parthenocarpic
fruit. An orange contain seeds with more than one embryo thus, it shows polyembryony.
0.45. (a) How are parthenocarpic fruits produced by some plants and apomictic seeds by some
others? Explain.
(b) When do farmers prefer using apomictic seeds? [CBSE (AI) 2016]
Ans. (9) Parthenocarpic fruits are formed when ovary develops into fruit without fertilisation.
Apomictic seeds are formed when formation of seeds take place without fertilisation.
(b) Tomaintain hybrid characters (year after year in a desired plant) and to avoid buying hybrid
seeds every year (expensiveseeds) farmers prefer using apomictic seeds.
Q. 46. What is agamospeny? How is agamospermy different from parthenogenesis and parthenocarpy?
Ans. The phenomenon of asexual reproduction that mimics sexual reproduction as it forms seed
without fertilisation is called agamospermy.
Parthenogenesis refers to the development of unfertilised egg into an adult individual. On the
other hand, parthenocarpy is the phenomenon of formation of fruits without fertilisation of an
ovary.
PONSE QU
AS PER
NEP LongAnswer Questions-I
KSNOS
Each of the following questions are of 3 marks.
Q.1. (a) Name the organic material exine of the pollen grain is made up of. How is this material
advantageous to pollen grain?
(6) Still it is observed that it does not form a continuous layer around the pollen grain. Give
reason.

(c) How are 'pollen banks' useful? [CBSE (A) 2016]

Ans. (a) Sporopollenin.
It is most resistant material to high temperature, strong acids on alkali and no enzymes can
degrade it.
Sexual Reproduction in Flowering Plants 41
 (b) Germs pores are present to allow pollen tube to emerge out for pollen
() Pollen banks help in storing pollen grains for years for crop breeding
Q. 2. Write the functions of:
germinatio
programmes.n.
(a) Coleoptile (b) Tapetum (c) Scutellum
Ans.
(a) Coleoptile: It protects the plumule of the monocot embryo. CBSE Delhi 201)
(b) Tapetum: Itprovides nourishment to developing pollen.
(o) Scutellum: It provides nourishment and protection to the developing embryo,
Q.3. When and where do tapetum and synergids develop in flowering plants?
Ans.
functions.
Tapetum: Microsporogenesis, Microsporangium (Anther), nourishes the
ICBSE Ment
2019io(n
5 the
7121
grains.
Synergids: Megasporogenesis, Megasporangium (ovule), synergids have filiform
developing polla
guide the pollen tube into it. apparatus y
[CBSE Marking Scheme 2019 (57/2h
Q.4. Where are the following structures present in a male
the function of each one of thenm. gametophyte of an angiosperm? Mentio
(a) Germ pore (6) Sporopollenin
(c) Generative cell
[CBSE 2019 (57I21
Ans. (a) Germ pore: Pollen grain exine, site from
where pollen tube emerges.
(6) Sporopollenin: Exine
of pollengrains, protects the pollen grains from
/and
strong acids & alkali / enzymes/ adverse condition. high temperatur
(c) Generative cell: Pollen grains, give rise
to two male gametes.
lCBSE Marking Scheme 2019 (5712/1
Q.5. Draw the diagram of
microsporangium
function of its innermost wall layer.
of an angiosperm and label any four parts. State t
Ans. Refer to Fig. 1.3(b). [CBSE Sample Question Paper 2015, 2017, 201
Tapetum nourishes the developing pollen grains.
Q.6. Make a list of any three
outbreeding devices that
how they help to encourage cross-pollination. flowering plants have developed and explu
Ans. (i) Time of pollen release and stigma [CBSE (AI) 201
self-pollination.
receptivity are different (not synchronised). This preve
(ii) Anther and stigma are placed at
with the stigmaof the same flower.
different positions, so the pollens cannot come in cont
(iii) Self-incompatibility, which is a genetic mechanism to prevent the pollen
stigma of the same flower. germination onth
Q.7. Why are angiosperm anthers called
dithecous? Describe the structure of its microsporangius
Ans. The anthers of [CBSE (A) 201:
has two theca.
angiosperms are called dithecous because they are bilobed and each lobe of ant
Microsporangium is surrounded by four wall layers named as epidermis, endothecium, mnide"
layer and tapetum. In young anther, agroup of compactly arranged
sporogenous tisSue occupies the centre of each microsporangium homogenous cells ca
pollen grains. which produce microspore
0.8. Differentiate between thefollowing:
(a) Perisperm and Pericarp
(b) Syncarpous pistil and Apocarpous pistil
(c) Plumule and Radicle
lCBSE 2023 (57/1/)
42 Xam idea Biology-XI1
Ans. (a)

S. No. Perisperm Pericarp

(i) It represents persistent remains of It represents the wall of fruit formed by the
nucellus (of ovule) in the seed. Ovarian wall.

(ii) This is a part of seed. This is a part of fruit.

(iii) It is usually dry. It can be dry or fleshy.

(b)
Syncarpous pistil Apocarpous pistil
1. The condition where allthe pistils are fused or 1.The condition where the pistils are free.
combined.
2. For example, tomato and cucumber. 2. For example, lotus.
(c)
Plumule Radicle

1. It is the part of the embryo that gives rise to 1.It is the part of the embryo that gives rises to
the shoot. the root.
2. It growsafter the radicle. 2. It grows before the plumule.

0.9. Draw a longitudinal section of the pistil from a flowering plant, where pollination has
occurred. Label the following:
(a) Stigma showing germinating pollen grains
(b) Style
(c) Pollen tube reaching the micropyle of the ovule
(d) Embryo sac
(e) Components of the egg apparatus [CBSE 2020 (57/2/1)]

Ans.
-Stigma /(a)

Style /(b)
Pollen tube (c)
-Embryo sac /(d)

Eggcell /(e) egg

Synergid /(e) apparatus
Y½ x 6
[CBSE Marking Scheme 2019 (57/2/1)1

Q.10. (a) Draw alabelled sketch of amature 7-celled, &-nucleate embryo-sac.

(b) Which oneof the cell in an embry0-sacproduce endosperm after double fertilisation?
[CBSE (F) 2016]
Ans. (a) Refer to Fig. 1.8(c)
(b) Central cell

Sexual Reproduction in Flowering Plants 43

Q. 11. Draw a schematictransverse section of a mature anther of an angiosperm. Label
middle layers, tapetum, endothecium, sporogenous tissue and the connectiye its
Ans.
13.
epidem
[CBSE 2020 (57

(Topper's Answer 2020

Q. 12. Given below are the events that are
observed in
them in the correct sequential order in whichartificial hybridisation programme. Arran;
they are followed in the hybridisati
programme.
(a) re-bagging; (b) selection of parents;
(c) bagging: (a) dusting the pollen on stigma;
(e) emasculation; () collection of pollen from male parent.
Ans. (b); (e); (c); (): (d); (a). [NCERT Exemplar] [HOT
Q. 13. One of the major approaches of crop
improvement
Explain the steps involved in making sure that onlyprogramme
is Artificial Hybridisati:
the desired pollen grain pollinate :
stigma of a bisexual flower by a plant breeder. [CBSE 2023 (57/5.
Ans. The steps involved in artificial hybridisation to make sure that only the
the stigma of a bisexual flower by plant breeder are: desired pollen pollin:
1. Anthers are removed from the bisexual flowers using forceps.
This is emasculation and
done before the anther dehisces.
2. The emasculated flower is covered with a paper bag to prevent
pollens. This is called bagging. contamination from unwant
3. On attaining maturity, mature pollens from desirable plant are dusted on stigma of bagg
flower and rebagged for fruit development.
Q. 14. Differentiate between geitonogamy and xenogamy in plants. Which one between the two w
lead to inbreeding depression and why? [CBSE Delhi 201
Ans. Table 1.10: Differences between geitonogamy and xenogamy
S. No.
Geitonogamy Xenogamy
(i) It is transfer of pollen grains from the anther It is transfer of pollen grains from the anthe
to the stigma of another flower of same plant. to the stigma of a different plant.
(iü) The pollen grains are genetically similar to the The pollen grains are genetically differen
plant. from the plant.
Geitonogamy will lead to inbreeding depression because the pollen grains are genetically s
which results in inbreeding.Continued inbreeding willthus reduce fertility and productiviy
44 Xam idea Biology-Xl
 15 Write the differences between wind-pollinated and insect-pollinated flowers. Give an example
of each type. [CBSE (E) 2014, 2020]
Ans.
Table 1.11: Differences between wind-pollinated and insect-pollinated flowers
S. No. Wind-pollinated fAowers Insect-pollinated flowers
() These produce large numbers of pollen grains. These produce less number of pollen grains.
These are dull, nectarless and scentless. These are bright, scented and have nectar.
(ii)
(i) Stamens are long and protrude above petals. Stamens lie within the corolla tube.
(iv) The pollen grains are dry, light, small and The pollen grains are larger, heavier with
smooth. appendages like hooks and barbs.
For example, ragweed. For example, sunflower.

o16. (a) Write the characteristic features of anther, pollen and stigma of wind-pollinated flowers.
(b) How do flowers reward their insect pollinators? Explain. [CBSE (A) 2010, 2012]
Ans. (a) The characteristics of wind-pollinated flowers are:
(i) Pollen grains are light in weight, non-sticky, dry and winged, so that they can be easily
transported.
(ii) Well-exposed stamens for easy dispersal of pollen grains in the wind.
(iüi) The stigma is sticky, large, feathery to trap pollen grains in air.
(io) Numerous flower are packed together to form inflorescence.
(0) The flowers are small and inconspicuous.
(b) Insect pollinators are rewarded in following ways:
() The flowers offer floral reward like nectar and pollen grain.
(ii) In some species floral reward provides safe place to lay eggs.
Q.17. (a) Mention any four strategies adopted by flowering plants to prevent self-pollination.
(b) Why is geitonogamy also referred to as genetical autogamy? [CBSE (AI) 2010]
Ans. (a) Refer to Points to remember 5[Contrivances for cross-pollination (Xenogamy/Allogamy)].
(b) Geitonogamy is the transfer of pollen grains from the anther to the stigma of another flower
of the same plant. Although geitonogamy is functionally cross-pollination involving a
pollinating agent, genetically it is similar to autogamy, since the pollen grains come from the
same plant.
Q. 18. State the signifcance of pollination. List any four differences between wind-pollinated and
animal pollinated fowers.
Ans. Pollination is the phenomena of transfer of pollen grains from anthers to the stigma of a pistil.
Pollination is prerequisite for the beginning of fertilisation.
Table 1.12: Differences between wind-pollinated and animal-pollinated flowers
S. No. Wind-pollinated lowers Animal-pollinated flowers
() This kind of flower is pollinated by abiotic This kind of flower is pollinated by biotic
pollinating agent. pollinating agent.
(ii) They are small and inconspicuous. They are large, colourful, fragrant and rich in nectar.
(111) The pollen grains are dry, light and non-sticky| The pollen gains are generally sticky in animal
so that they can be easily transported by wind. pollinated flowers.
(iv) The flowers are often clustered so as to carry Flowers reward pollinators in terms of pollen,
out pollination. nectar or safe place to lay eggs.
Q. 19, (a) How does cleistogamy ensure
autogamy?
(6) State one advantage and one disadvantage of cleistogamy to the plant.
[CBSE (A) 2012; Delhi 2013]
Sexual Reproduction in Flowering Plants 45
 to land on
Ans. (a) Cleistogamous flowers do not open. Therefore, the pollens have the
same flower. This ensures autogamy.
(b) Advantage: Self-pollination is assured, thus ensuring seed formation.
stigma of
Disadvantage: Least variations observed and it leads to inbreeding depression
Q. 20. (a) Describe the endosperm development in coconut.
(b) Why is tender coconut considered a healthy source of nutrition?
(c) How are pea seeds different from castor seeds with respectto endosperm?
Ans. (a) The primary endospermnucleus(PEN) undergoes successive nuclear divisions 2|CBSE (
(AI) 201
to give
free nuclei. Subsequently, cell wallis formed towards the periphery and rise
cellular, leaving free nuclear endosperm in the central part. This division is endosperm becom
cytokinesis and thus endosperm becomes cellular and is called cellular endosperm
(b) It is rich in many nutrients like fats, proteins, carbohydrates, minerals, vitamins u
fol owed
tender coconut is considered a healthy source of nutrition.
(©) In peas,the endosperm is used up and there is no endosperm present in the mature seed:
castor, the endosperm remains intact in the mature seed.
Q.21. Differentiate between perisperm and endosperm by giving one example of each.
Ans.
Table 1.13: Differences between perisperm and endosperm
[CBSE (AI) 2011
S. No.
Perisperm Endosperm
(i) It is persistent nucellus. It is the nutritive tissue for embryo.
(1) It is diploid. It is triploid.
(ii) Example: black pepper, beet. Example: maize, rice, wheat, castor.
Q. 22. Explain any three advantages the seeds offer to angiosperms. [CBSE 2020, Dellhi 2014
Ans. () Since reproductive process such as pollination and fertilisation are
seed formation is more dependable.
independent of wak
(ii) Seeds have better adaptive strategies for dispersal to new
colonise in other areas.
habitats and help the species
(iii) As they have sufficient food reserves young seedlings are
nourished until they are capable
photosynthesis on their own.
(iv) The hard seed coat provides protection to the young embryo.
(v) Being products of sexual reproduction, they generate new genetic
variations.
combinations
(Any thra
O. 23. State what is apomixis. Comment on its significance. How can it be
commercially used?
[CBSE (AI) 2015; 2019 (57A!
Ans. It is a special mechanism of asexual reproduction that mimics sexual
reproduction (to produ
seeds without fertilization), there is no segregation of characters in the
progeny, farmers d
develop apomicts of hybrids and use them year after year to cut the cost.
[CBSE Marking Scheme 2019 (5714
o. 24. (a) How does a farmer use the dormancy of seeds to his
advantage?
(b) What advantages a seed provides to a plant? [CBSE (AI) 201
Ans. (a) Dormancy of mature seeds are important for storage of seeds which can be used as o
throughout the year and also to raise crop in the next season.
(b) Seeds offer several advantages to angiosperms. Firstly, since
reproductive processes s
pollination and fertilisation are independent of water, seed formation is more dependa
Alsoseeds have better adaptive strategies for dispersal to new habitats and help the spec
colonise in other areas. As they have sufficient food reserves, young seedlings are nourishe

46 Xam idea Biology-Xl

 until they are capable of photosynthesis on their own. The hard seed coat provides protection
to the voung embryo. Being products of sexual reproduction, they generate new genetic
combinations leading tovariations.
o25, Differentiate between parthenocarpy and parthenogenesis. Give one example of each.
(CBSE 2018]
Ans.
Paudhenecanpt pheducten it withaut
ntlaaten n planta. g Banae
|Tatkewoqnesis
animale its a
dulagmnt
)nollvidual ganam
mati gamute
without

[Topper's Answer 2018]

026. Fora layman, both apple and banana are fruits. But a biology student categorises fruits as true
fruits, false fruits and parthenocarpic fruits. Justify. [CBSE 2020 (57/1/2)]

Ans. True Fruits: Fruits that develop from mature ovary and are a result of fertilisation. 1
False Fruits: Fruits that develops from ovary along with some other floral parts / thalamus. 1

Parthenocarpic Fruits: Fruits that develop without fertilisation. 1

[CBSE Marking Scheme 2020 (57/1/2)]
0.27. Fertilisation is not an obligatory event for fruit production in certain plants. Explain the
statement. [HOTS]
Ans. This can be observed in parthenocarpic fruits. The 'seedless fruits' that are available in the
market, such as cucumber, grapes, etc., are good examples. Flowers of these plants are sprayed
by agrowth hormone that induces fruit development even though fertilisation has not occurred.
The ovules of such fruits, however, fail todevelop into seeds.
Q.28. Explain the process of pollination in Vallisneria. How is it different in water-lily, which is also
an aquatic plant? [CBSE 2017 (57/2/1)]
Ans.
hydnophikzpliat ies polinaten
done ith he
an
44uate plant fomd
stalke Male foueou

polinatin e Coveede th
to

aquitie plant .ú pollinaled

the lase
lante.i
abov he
ten
|Topper's Ansver 2017]

Sexual Reproduction in Flowering Plants 47

 54

iology-XI
idea
Xam Q. Ans.
29. Q.
28.
(c) (6) Answer (a) A (e) (a) (c)
flower (b) (a) (c) (d) (c) (h) (a) Gire ()
Howpollination
What What aregermination.
Inrequired for persists
Toprotect uring The
formation. Toapplematures.
integuments mostreasons globular,
Refer
notapple Micropyle groundout
micropyle The
many would the
is tomato of true groundnut obtain and to 7\2ote
following
the and the embryo
and zxgotes
megaspore have of fruits. remain nutrition
cashew why: Iig. heart
minimum
its plant cashew,
embryo used
is remains
of seeds in 1.13 (in
beenpistil?questions
development. seeds shaped the
from are ovuleangiosperms
as an are (b ).
following apart and a up as embiyo
mother the number small
during are not exalbuminous
keep thecalled small a and
minimum from exalbuminous
pore harden mnat ure sa)
cells
giving
the the Whereas,
seed endosperm pore divide
ofprocess ovary, seed in true divdes
were pollenreasons: germinatiorn. the and inand cmbryo
number viable, fruits. the only
thalamus seed castor the
involved? because for castor after
grains sexual
of
until coat the
seed as
seeds water
of
favourable of developing coatseedscertain shown
ovules also
that
reproduction a are the content
contributes seed
endosperm ofa are in
present must albuminous seed. amount the
conditions for
embryo, albuminous.
is diagram.
have th e highly
in entry of
produce to is [CBSE
the been fruitretun because
completely zygotes, endosperm
ovary? of reduced,
water (AI)
involved 240 formation
for the divide 2011]
viable germira is
and endos Cons as
the
for.
 (d) What is the minimum number of microspore mother cells involved in the above case?
(e) How many male gametes were involved in this case? |CBSE Delhi 2015) [HOTS]
Ans. (a) 240 pollen grains. One pollen grainparticipates in fertilisation ofone ovule.
(b) 240 ovules. One ovule after fertilisation forms one seed.
240 MMC were involved. Each MMC forms four megaspores out of which only one remains
functional.
( 60 MMCs (240/4 =60). Each microspore mother cell meiotically divides to form four pollen
grains.
i A80 male gametes (240 x 2 = 480). Each pollen grain carries two male gametes (which
participate in double fertilisation).
o30. Aflower of brinjal plant following the process of sexual reproduction produces 360 viable seeds.
Answer the following questions giving reasons:
(a) How many ovules are minimally involved?
(b) How many megaspore mother cells are involved?
(c) What is the minimum number of pollen grains that must land on stigma for pollination?
(d) How many male gametes are involved in the above case?
(e) How many microspore mother cells must have undergone reduction division prior to
dehiscence of anther in the above case? [CBSE Delhi 2015] [HOTS]
Ans. (a) 360 ovules are involved. One ovule after fertilisation forms one seed.
(b) 360 MMCare involved. Each MMC forms four megaspores out of which only one remains
functional.
(c) 360 pollen grains. One pollen grains participates in fertilisation of one ovule.
(d) 720 male gametes are involved. Each pollen grain carries two male gametes (which participate
indouble fertilisation) (360 x 2 =720).
(e) 90 MMC undergo reduction division. Each microspore mother cell meiotically divides to
form four pollen grains. (360/4 = 90).
Q. 31. (a) Acapsicum flower has 240 ovules in its ovary. But, it produces a fruit with only 180 viable seeds.
Explain giving a reason that could be responsible for such a result.
(b) Describe the development of an endosperm in a viable seed. Why does endosperm
development precede embryo development?
(c) Givean example of an angiosperm seed that has a perisperm. Name the part the perisperm
[CBSE Delhi 2017]
develops from.
Ans. (a) (i) 240 ovules giving rise to only 180 viable seeds, can be possible only if less number of
pollen grains or male gametes were available.
() Allpollen grains did not germinate or did not form pollen tubes.
(ii) Many pollen were not compatible.
(6) For the development of an Endosperm, Refer to Points to remenmber 9.
Cells of endosperm are filled with reserve food materials that are used for nutrition of
developing embryo. Thus endosperm needs to develop before embryo.
(c) Black pepper and beet have a perisperm. The perisperm develop from the nucellus.
Q.32. (a) Seeds offer several advantages to angiosperms. Describe any three such advantages.
(6) Why is banana called a parthenocarpic fruit? Would you call banana a true fruit? Give
reason in support of your answer.
Ans. (a) Following are their advantages:
() Better adaptive strategies for dispersal to new habitats.
(i) Hard seed coat provides protection to young embryo
(i) Sexual reproduction--newgenetic combinations.
Sexual Reproduction in Flowering Plants 55
 (iv) Sufficient food reserves for the seedling.
() Basis of agriculture storage of seeds can occur due to seed dormancy
(6) Banana fruit develops without fertilisation therefore, it is called
Yes, it is a true fruit because it develops from ovary.
parthenocarpic
Questions for Practice
1. Choose and write the correct
option in the following questions.
(i) Filiform apparatus performs the
functions of
(a) opening the pollen tube.
(b) guiding the pollen tube to egg.
(c) entry of pollen tube into
synergids.
(d) prevents growth of more than
one pollen tube.
(i) Which of the following is true
for typical bilobed anther?
(a) 2 theca, 2
(c) 4 theca, 2
sporangia (b) 4theca, 4
sporangia
(iii) The sporangia (d) 2 theca, 4
sporangia
outermost and innermost wall layers of
respectively
(a)
microsporangium in an anthe
endothecium and tapetum
(c) epidermis and (b) epidermis and
endodermis
INCERT Exem
middle layer(d) epidermis and
(iv) Agroup of tapetum
compactly arranged homogenous mass
mierosporangium in an anther is: of cellsoccupying the centre of at
(a) Sporogenoustissue [CBSE 2022 (57/3/4), Ter
(b) Pollen sacs
(c) Micorspore tetrads
(u) Seeds of an (d) Spores
orange when taken out and
and shapes. The reason for this is as manysqueezed, show many embroys of different
embroys have developed from:
(a) Egg cells [CBSE 2022
fusing with different male
(b) PEN fusing with gametes forming embroys. (57/3/4), Ter
(c) Nucellarcells different male gametes forming embroys.
(d) Synergids dividing and developing into embroys.
(vi) Figure (i) anddividing anddeveloping intoembroys.
Figure (ii)
typical angiosperm plant. given below are showing two stages of
megasporogenesls
[CBSE 2022 (57/3/4), Tem
(Y) (X)

(Z)

Fig. ()
Fig.(i)
56 Xam idea Biology-XIl