NCERT Exemplar Class 12 Biology Solutions Chapter 2 Sexual Reproduction in Flowering Plants

Q: What is the difference between self-pollination and cross-pollination?

Self-Pollination Cross-Pollination Pollen transfers to the same flower/plant Pollen transfers to another plant No external agents required Requires pollinators (e.g., insects, wind) Reduces genetic diversity Enhances genetic diversity Example: Peas, sunflowers Example: Apples, strawberries

Q: How is double fertilization unique to angiosperms?

Double fertilization involves: First fusion : One sperm + egg → diploid zygote. Second fusion : Second sperm + polar nuclei → triploid endosperm (nutritive tissue). This ensures embryo nourishment and is exclusive to flowering plants

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Did you know that over 80% of all plant species reproduce through sexual reproduction involving flowers? The chapter Sexual Reproduction in Flowering Plants talks about how plants reproduce using flowers. It includes topics like pollination, fertilisation, seed and fruit formation, and all the steps involved. NCERT Exemplar Class 12 Biology Solutions Chapter 2 helps in easily understanding these topics. It covers important terms like microsporogenesis, megasporogenesis, double fertilisation, and more. These are useful for both board exams and entrance exams. With these NCERT Exemplar Solutions, it becomes easier to study and revise the chapter properly.

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Find Answers of NCERT Exemplar for Class 12 Science Chapter 2 (Multiple Choice Questions)
Get Answers to Class 12 Science Chapter 2 NCERT Exemplar (Very Short Answer Questions)
Access Answers to NCERT Exemplar Class 12 Chapter 2 Sexual (Short Answer Questions)
Know Answers to NCERT Exemplar for Class 12 Science Chapter 2 (Long Answer Questions)
Approach to solve of Class 12 Biology Chapter 2 questions
Important Topics of Class 12 Biology Chapter 2
Important Question from NCERT Exemplar Class 12 Biology Chapter 2
NCERT Exemplar Class 12 Biology Chapter Wise Links

NCERT Exemplar Class 12 Biology Solutions Chapter 2 Sexual Reproduction in Flowering Plants

The NCERT Exemplar Solutions for Class 12 Biology have all types of questions like MCQs, short answers, long answers, and diagrams. The questions are made to cover all important points. The answers are simple and step-wise, so it’s easy to follow and learn. It helps to clear the chapter and prepare well for the exams. They save time during revision and also give an idea of how questions can be asked in exams. With regular practice from an exemplar, students can get better marks and feel more confident. These NCERT Exemplar Solutions for Class 12 are also helpful when you are solving other reference books or preparing for the NEET.

Find Answers of NCERT Exemplar for Class 12 Science Chapter 2 (Multiple Choice Questions)

In this section, students will find different forms of questions, such as MCQs, short and long answers, by which they can check what they have learned and improve their accuracy.

Question:1

Among the terms listed below, those that are not technically correct names for a floral whorl are:
i. Androecium
ii. Carpel
iii. Corolla
iv. Sepal
(a) i and iv, (b) iii and iv (c) ii and iv (d) i and ii.

Answer:

Carpel and sepal are not technically names for floral whorls. The correct whorls are calyx (sepals), corolla (petals), androecium (stamens), and gynoecium (carpels). So, while corolla and androecium are whorls, carpel and sepal are individual components of gynoecium and calyx respectively. So technically, they don’t qualify as the full whorl names.

Hence, the correct answer is option (c) ii and iv.

Question:2

The embryo sac is to an ovule as _______ is to an anther.
a. Stamen
b. Filament
c. Pollen grain
d. Androecium

Answer:

The embryo sac is the female gametophyte inside the ovule, and by analogy, the male gametophyte inside the anther is the pollen grain. Both are structures where gametes are produced. So, pollen grains relate to anther the way embryo sacs relate to ovules.

Hence, the correct answer is option (c) Pollen grains.

Question:3

In a typically complete, bisexual and hypogynous flower, the arrangement of floral whorls on the thalamus from the outermost to the innermost is:
a. Calyx, corolla, androecium and gynoecium
b. Calyx, corolla, gynoecium and androecium
c. Gynoecium, androecium, corolla and calyx
d. Androecium, gynoecium, corolla and calyx

Answer:

In a typical complete, bisexual, and hypogynous flower, the floral whorls are arranged on the thalamus in a specific order from outside to inside: calyx (sepals), corolla (petals), androecium (stamens), and finally gynoecium (carpels). This is the standard concentric pattern in floral anatomy.

Hence, the correct answer is option (a) Calyx, corolla, androecium and gynoecium.

Question:4

A dicotyledonous plant bears flowers but never produces fruits and seeds. The most probable cause for the above situation is:
a. The plant is dioecious and bears only pistillate flowers
b. The plant is dioecious and bears both pistillate and staminate flowers
c. The plant is monoecious
d. The plant is dioecious and bears only staminate flowers.

Answer:

If a dicot plant produces flowers but never fruits or seeds, it's likely that the plant bears only male (staminate) flowers. That means there’s no ovary to get fertilised, and hence, no seed or fruit formation can occur. Pistillate flowers could still form fruit via pollination, so they aren't the issue here.

Hence, the correct answer is option (d) The plant is dioecious and bears only staminate flowers.

Question:5

The outermost and innermost wall layers of microsporangium in an anther are respectively:
a. Endothecium and tapetum
b. Epidermis and endodermis
c. Epidermis and middle layer
d. Epidermis and tapetum

Answer:

In a typical microsporangium (pollen sac), the outermost wall is the epidermis, which protects the anther. The innermost layer is the tapetum, which nourishes developing pollen grains. These layers surround the pollen mother cells inside.

Hence, the correct answer is option (d) Epidermis and tapetum.

Question:6

During microsporogenesis, meiosis occurs in:
a. Endothecium
b. Microspore mother cells
c. Microspore tetrads
d. Pollen grains.

Answer:

Microsporogenesis is the process where diploid microspore mother cells undergo meiosis to form haploid microspores, which then become pollen grains. So, the actual meiotic division occurs at the microspore mother cell stage.

Hence, the correct answer is option (b) Microspore mother cells.

Question:7

From among the sets of terms given below, identify those that are associated with the gynoecium.
a. Stigma, ovule, embryo sac, placenta
b. Thalamus, pistil, style, ovule
c. Ovule, ovary, embryo sac, tapetum
d. Ovule, stamen, ovary, embryo sac

Answer:

The gynoecium is the female reproductive part of a flower and includes the stigma, ovary, ovule, embryo sac, and placenta. Other parts like the thalamus (base of flower), tapetum (part of anther), and stamen (male organ) are unrelated.

Hence, the correct answer is option (a) Stigma, ovule, embryo sac, placenta.

Question:8

Starting from the innermost part, the correct sequence of parts in an ovule is,
a. egg, nucellus, embryo sac, integument
b. egg, embryo sac, nucellus, integument
c. embryo sac, nucellus, integument, egg
d. egg, integument, embryo sac, nucellus.

Answer:

The innermost part of the ovule is the egg cell, which lies inside the embryo sac. That sac is encased by the nucellus, and the entire structure is protected by outer integuments. So, the logical progression from inner to outer is egg → embryo sac → nucellus → integuments.

Hence, the correct answer is option (b) Egg, embryo sac, nucellus, integument.

Question:9

From the statements given below, choose the option that is true for a typical female gametophyte of a flowering plant:
i. It is 8-nucleate and 7-celled at maturity
ii. It is free-nuclear during the development of
iii. It is situated inside the integument but outside the nucellus
iv. It has an egg apparatus situated at the chalazal end
(a) i and iv, (b) ii and iii, (c) i and ii, (d) ii and iv

Answer:

The mature female gametophyte (embryo sac) of a flowering plant is typically 8-nucleate and 7-celled—two synergids, one egg cell, three antipodals, and two polar nuclei. It’s free-nuclear in early development before cellularisation. The egg apparatus is located at the micropylar end, not the chalazal end.

Hence, the correct answer is option (c) i and ii.

Question:10

Autogamy can occur in a chasmogamous flower if:
a. Pollen matures before the maturity of the ovule
b. Ovules mature before the maturity of pollen
c. Both pollen and ovules mature simultaneously
d. Both anther and stigma are of equal length.

Answer:

Autogamy means self-pollination within the same flower. In chasmogamous flowers (those that open), autogamy can only occur if both the anthers and ovules mature at the same time—ensuring the pollen is viable when the ovule is ready. Timing is everything here!

Hence, the correct answer is option (c) Both pollen and ovules mature simultaneously.

Question:11

Choose the correct statement from the following:
a. Cleistogamous flowers always exhibit autogamy
b. Chasmogamous flowers always exhibit geitonogamy
c. Cleistogamous flowers exhibit both autogamy and geitonogamy
d. Chasmogamous flowers never exhibit autogamy

Answer:

Cleistogamous flowers never open, so the only pollen available is their own. That makes autogamy a default mode of pollination. Since no cross-pollination is possible, these flowers are perfect examples of nature’s lockdown mechanism for ensuring reproduction.

Hence, the correct answer is option (a) Cleistogamous flowers always exhibit autogamy.

Question:12

A particular species of the plant produces light, non-sticky pollen in large numbers, and its stigmas are long and feathery. These modifications facilitate pollination by:
a. Insects
b. Water
c. Wind
d. Animals

Answer:

Wind-pollinated plants produce enormous quantities of dry, lightweight, non-sticky pollen that can travel with air currents. Their feathery stigmas are specially adapted to trap this airborne pollen. It’s all about using the breeze to do the matchmaking.

Hence, the correct answer is option (c) Wind.

Question:13

From among the situations given below, choose the one that prevents both autogamy and geitonogamy.
a. A monoecious plant bearing unisexual flowers
b. A dioecious plant bearing only male or female flowers
c. Monoecious plant with bisexual flowers
d. Dioecious plant with bisexual flowers

Answer:

In a monoecious plant with unisexual flowers (male and female on the same plant), autogamy can't occur because the flowers aren’t bisexual. And geitonogamy (transfer between flowers of the same plant) can be prevented with spatial or temporal separation. So both types of self-pollination are avoided.

Hence, the correct answer is option (a) A monoecious plant bearing unisexual flowers.

Question:14

In a fertilised embryo sac, the haploid, diploid and triploid structures are:
a. Synergid, zygote and primary endosperm nucleus
b. Synergid, antipodal and polar nuclei
c. Antipodal, synergid and primary endosperm nucleus
d. Synergid, polar nuclei and zygote.

Answer:

After double fertilisation, the embryo sac contains haploid synergids, a diploid zygote formed by egg + sperm, and a triploid primary endosperm nucleus formed by the fusion of two polar nuclei with one sperm nucleus. Classic 1n + 1n and 2n + 1n combos.

Hence, the correct answer is option (a) Synergid, zygote and primary endosperm nucleus.

Question:15

In an embryo sac, the cells that degenerate after fertilisation are:
a. Synergids and primary endosperm cell
b. Synergids and antipodals
c. Antipodals and primary endosperm cell
d. Egg and antipodals.

Answer:

Once fertilisation is complete, the synergids (which guide the pollen tube) and the antipodals (which play a nutritive role) degenerate. The egg becomes the zygote and the polar nuclei give rise to endosperm, so they stick around.

Hence, the correct answer is option (b) Synergids and antipodals.

Question:16

While planning for an artificial hybridisation programme involving dioecious plants, which of the following steps would not be relevant:
a. Bagging of female flower
b. A dusting of pollen on stigma
c. Emasculation
d. Collection of pollen

Answer:

In dioecious plants, male and female flowers are on separate plants. So emasculation (removal of male parts) is not needed since the female plant doesn’t have any. You still need to collect pollen, dust it on the stigma, and bag the female flower to avoid unwanted pollination.

Hence, the correct answer is option (c) Emasculation.

Question:17

In the embryos of a typical dicot and a grass, true homologous structures are:
a. Coleorhiza and coleoptile
b. Coleoptile and scutellum
c. Cotyledons and scutellum
d. Hypocotyl and radicle

Answer:

The scutellum in monocots is the functional equivalent of cotyledons in dicots. It absorbs nutrients from the endosperm for the growing embryo. Though they look different, they perform the same job—making them true homologues.

Hence, the correct answer is option (c) Cotyledons and scutellum.

Question:18

The phenomenon observed in some plants wherein parts of the sexual apparatus is used for forming embryos without fertilisation is called:

a. Parthenocarpy
b. Apomixis
c. Vegetative propagation
d. Sexual reproduction

Answer:

Apomixis is a form of asexual reproduction in flowering plants where seeds are formed without fertilisation. The embryo develops from diploid cells like the nucellus or integument, not from a zygote. It’s like nature’s shortcut to seed formation.

Hence, the correct answer is option (b) Apomixis.

Question:19

In a flower, if the megaspore mother cell forms megaspores without undergoing meiosis and if one of the megaspores develops into an embryo sac, its nuclei would be:
a. Haploid
b. Diploid
c. A few haploid and a few diploid
d. With varying ploidy.

Answer:

If the megaspore mother cell does not undergo meiosis and still forms a megaspore, that megaspore will remain diploid. And any embryo sac formed from that megaspore will also have diploid nuclei since no ploidy reduction took place.

Hence, the correct answer is option (b) Diploid.

Question:20

The phenomenon wherein the ovary develops into a fruit without fertilisation is called:
a. Parthenocarpy
b. Apomixis
c. Asexual reproduction
d. Sexual reproduction

Answer:

Parthenocarpy is the development of fruit without fertilisation. The ovary grows into a fruit, but since no fertilisation occurred, it has no seeds. Think of bananas or seedless grapes—nature’s fruity loophole.

Hence, the correct answer is option (a) Parthenocarpy.

Get Answers to Class 12 Science Chapter 2 NCERT Exemplar (Very Short Answer Questions)

The detailed answers to the very short answer questions are given below:

Question:1

Name the component cells of the ‘egg apparatus’ in an embryo sac.

Answer:

The egg apparatus consists of two synergids and one egg cell.

Question:2

Name the part of the gynoecium that determines the compatibility of pollen grains.

Answer:

The pistil can determine which pollen grains are compatible.

Question:3

Name the common function that cotyledons and nucellus perform.

Answer:

Cotyledons and nucellus contain abundant food that is utilized by the developing cells.

Question:4

Complete the following flow chart
Pollen mother cell → Pollen tetrad → Pollen grain (a) = vegetative cell (b) =?

Answer:

Pollen mother cell → Pollen tetrad → Pollen grain (a) = vegetative cell (b) =Generative cell

Question:5

Indicate the stages where meiosis and mitosis occur (1, 2 or 3) in the flow chart.
Megaspore mother cell →Megaspores → Embryo sac →Egg

Answer:

1. Meiosis 2. Mitosis 3. Mitosis

Question:6

In the diagram given below, show the path of a pollen tube from the pollen on the stigma into the embryo sac. Name the components of the egg apparatus.

Answer:

Longitudinal section of a flower showing growth of pollen tube.
Synergids and egg cells are the components of the egg apparatus.

Question:7

Name the parts of the pistil which develop into fruit and seeds.

Answer:

The ovary develops into fruits, and ovules develop into seeds.

Question:8

In the case of polyembryony, if an embryo develops from the synergid and another from the nucellus, which is haploid, and which is diploid?

Answer:

The embryo developing from the synergid will be haploid, and the embryo developing from the nucellus will be diploid.

Question:9

Can an unfertilized, apomictic embryo sac give rise to a diploid embryo? If yes, then how?

Answer:

We know that when seeds develop without fertilisation, it is known as apomixis. In this, the embryo can develop from the nucellus, which is diploid. Thus, an apomictic embryo sac can give rise to a diploid embryo.

Question:10

Which are the three cells found in a pollen grain when it is shed at the three-celled stages?

Answer:

When a pollen grain is shed at the three-celled stage, it contains 2 male gametes and a vegetative cell. The generative cell divides into two male gametes.

Question:11

What is self-incompatibility?

Answer:

When pollen from the same plant is incompatible for fertilisation, this condition is called self-incompatibility.

Question:12

Name the type of pollination in self-incompatible plants.

Answer:

In the case of self-incompatible plants, cross-pollination takes place.

Question:13

Draw the diagram of a mature embryo sac and show its 8-nucleate, 7-celled nature. Show the following parts: antipodals, synergids, egg, central cell, polar nuclei.

Answer:

mature embryo sac

Question:14

Which is the triploid tissue in a fertilized ovule? How is the triploid condition achieved?

Answer:

PEN or Primary Endosperm Nucleus shows triploid conditions. When one of the male gametes fuses with the polar nuclei, it results in the formation of triploid PEN.

Question:15

Are pollination and fertilisation necessary in apomixes? Give reasons.

Answer:

Pollination and fertilisation are not necessary for apomixis. Apomixis is a condition in which an embryo develops without fertilization.

Question:16

Identify the type of carpel with the help of the diagrams given below:
carpel

Answer:

Figure “a” shows the multicarpellary syncarpous condition, and figure “b” shows the multicarpellary apocarpous condition.

Question:17

How is pollination carried out in water plants?

Answer:

Water-mediated pollination takes place in a selected number of plants. For example, in Vallisneria, the female flower reaches the surface of the water. Pollen grains are sprinkled on the water surface, and they are passively transported to the female flower for pollination.
Another example is that of seagrasses, the female flower remains submerged in water, and pollen grains are released below the water surface. In the case of pollination by water, pollen grains have a mucilaginous covering which prevents the pollen from becoming wet.

Question:18

What is the function of the two male gametes produced by each pollen grain in angiosperms?

Answer:

The male gametes fuse with the female gametes and form the embryo. The embryo subsequently develops into a new plant. Another male gamete fuses with polar nuclei and eventually forms endosperm. The endosperm supplies food to the developing embryo.

Access Answers to NCERT Exemplar Class 12 Chapter 2 Sexual (Short Answer Questions)

The detailed answers to the Short answer questions are given below:

Question:1

List three strategies that a bisexual chasmogamous flower can evolve to prevent self-pollination (autogamy).

Answer:

The following are 3 strategies that a bisexual chasmogamous flower can evolve to prevent self-pollination or autogamy:

Pollen release and stigma receptivity are not synchronised in many flowers. Either the pollen is released much before the maturity of the stigma, or the stigma matures much before the release of pollen.
In some flowers, the anthers and stigma are placed in different places so that pollen grains from the same flower cannot reach the stigma.
Self-incompatibility between pollen and stigma is seen in some flowers. This is a genetically mediated process that prevents autogamy in these flowers.

Question:2

Given below are the events that are observed in an artificial hybridisation programme. Arrange them in the correct sequential order in which they are followed in the hybridisation programme.
(a) Re-bagging (b) Selection of parents (c) Bagging (d) Dusting the pollen on stigma (e) Emasculation (f) Collection of pollen from male parent.

Answer:

The correct sequence of steps in an artificial hybridisation programme is:

(b) Selection of parents → (e) Emasculation → (c) Bagging → (f) Collection of pollen → (d) Dusting on stigma → (a) Re-bagging

This order ensures that only desired pollen reaches the stigma and unwanted pollination is avoided.

Hence, the correct sequence is: b → e → c → f → d → a.

Question:3

Vivipary automatically limits the number of offspring in a litter. How?

Answer:

Viviparity is present in both animals and plants. In the case of animals, it means an animal gives birth to young ones. In the case of plants, viviparity means germination of the embryo on the plant itself, without the normal sequence of development of the seed. Viviparity involves too much drain of resources on the mother.
In the case of animals, a female has to constantly supply the nutrients and oxygen to the growing foetus if the foetus is developing in the womb. Enough resources are not available to support a large litter, and hence ,viviparity automatically limits the number of offspring in a litter. This is true in the case of plants also because a germinating embryo on the plant would require resources from the mother plant.

Question:4

Does self-incompatibility impose any restrictions on autogamy? Give reasons and suggest the method of pollination in such plants.

Answer:

Self- incompatibility is the condition in which pollen from the same plant cannot pollinate the flower. Thus, self-incompatibility imposes complete restriction on autogamy.
This evolution might have occurred to prevent too much inbreeding because continuous inbreeding prevents variations. In such plants, cross pollination is the norm and pollen from a plant pollinates the flower on another plant. This ensures the accumulation of gene pools from 2 different plants.

Question:5

In the given diagram, write the names of the parts shown with lines.

Answer:

Question:7

Are parthenocarpy and apomixis different phenomena? Discuss their benefits.

Hint: Yes, parthenocarpy, and different apomixis phenomena. Parthenocarpy leads to the development of seedless fruits. Apomixis leads to embryo development.

Answer:

Parthenocarpy is the condition in which fruits develop without seeds, while apomixis is a condition in which seeds develop without fertilisation. Fertilisation is absent in both cases, but seeds are present in apomixis only. Benefits of parthenocarpy: Seedless fruits are easier to consume, especially those fruits that naturally contain too many seeds, e.g., papaya, watermelon, and banana.
Benefits of Apomixis include the fact that it can be used to produce apomicts hybrid seeds every year. This will help in drastically cutting the cost for farmers.

Question:6

What is polyembryony, and how can it be commercially exploited?

Answer:

In some varieties of citrus and mango, the nucellar cells start dividing and protrude into the embryo sac. They eventually produce multiple embryos. This condition is called polyembryony. Embryos develop without fertilisation in this apomictic condition.
Polyembryony can be commercially exploited by producing seeds of hybrid varieties at a lower cost. In the case of hybrid plants, a farmer needs to buy seeds every year because plants from hybrid seeds fail to produce hybrid seeds due to the law of inheritance.
Buying fresh seeds every season is very costly. If hybrid seeds are produced with a polyembryonic condition, then it would be possible for the farmers to utilise those seeds for the next year and the subsequent years. This is still at the research stage, but there are bright prospects for the future.

Question:8

Why does the zygote begin to divide only after the division of the Primary endosperm cell (PEC)?

Answer:

The endosperm plays an important role in supplying food to the developing embryo. Once the division of PEC or Primary Endosperm Cell is complete, there is sufficient availability of food for the embryo.
In the absence of food, the zygote won’t be able to get the necessary raw materials for making new cells. Hence, the division of zygote beings only occurs after the division of the Primary Endosperm Cell (PEC).

Question:9

The generative cell of two-celled pollen divides into the pollen tube but not in three-celled pollen. Give reasons.

Answer:

In three-celled pollen, one of the cells is a vegetative cell that has no role to play in fertilisation. The remaining two cells are the male gametes, and they are the actual participants in fertilisation. Rather than the vegetative cells, the generative cells divide inside the pollen tube.
In 60% of the cases, the generative cell divides inside the pollen tube. In the remaining case, the generative cell divides much before pollination.

Question:10

In the figure given below, label the following parts: male gametes, egg cell, polar nuclei, synergid, and pollen tube.

Answer:

male gametes, egg cell, polar nuclei, synergid, and pollen tube

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Know Answers to NCERT Exemplar for Class 12 Science Chapter 2 (Long Answer Questions)

The detailed answers to the long-answer questions are given below:

Question:1

Starting with the zygote, draw the diagrams of the different stages of embryo development in a dicot.

Answer:

different stages of embryo development in a dicot.

Question:2

What are the possible types of pollinations in chasmogamous flowers? Give reasons.

Answer:

Chasmogamous flowers are open flowers in which stigma and anthers are exposed, and the flowers are similar to other species. Possible types of pollination in chasmogamous flowers are as follows:

Geitonogamy: The situation in which pollen grains from the same plant but different flower reaches the stigma is called geitonogamy. This is similar to autogamy because the zygote gets the gene pool from the same plant.
Xenogamy: The situation in which the pollen grains from a different plant reaches the stigma is called xenogamy. This can be termed as the true cross-pollination because the zygote gets the gene pool from 2 different plants.

Most of the plants produce hermaphrodite flowers, and thus, self-pollination is a clear-cut eventuality. However, continuous self-pollination can result in inbreeding depression. The variation will not be possible in the case of self-pollination. Hence, plants have evolved in various ways and means to facilitate cross-pollination even in dioecious flowers. One of the strategies followed by plants is a loss of synchronisation between pollen release and stigma maturity. Another strategy is self-incompatibility between pollens and the stigma of the same flower.
A third strategy is a positional difference between anthers and stigma so that pollens from the same flower are unable to reach the stigma.

Question:3

With a neat, labeled diagram, describe the parts of a mature angiosperm embryo sac. Mention the role of synergids.

Answer:

Structure of a mature Embryo Sac: A mature embryo sac is a 7-celled structure and has 8 nuclei. The end near the micropyle is called the micropylar end, while the opposite end is called the chalazal end. The following are the main parts of the embryo sac:

Egg Apparatus: The egg apparatus is composed of two synergids and an egg. There are special thickenings at the micropylar end of the synergids. These thickenings are known as the filiform apparatus.
The function of Synergids: The synergids provide a channel for the pollen tube to enter through the filiform apparatus.
Polar Nuclei: The two nuclei enclosed in the central cell are called polar nuclei.
Antipodals: The three cells at the chalazal end are called antipodals.

Question:4

Draw the diagram of a microsporangium and label its wall layers. Write briefly on the role of the endothelium.

Answer:

endothelium
Role of Endothecium: Endothecium, along with the epidermis and the middle layer, protects the pollens during development. Once pollen grains are mature, the three layers (including endothecium) rupture and thus facilitate the dehiscence of pollens.

Question:5

Embryo sacs of some apomictic species appear normal but contain diploid cells. Suggest a suitable explanation for the condition.

Answer:

The condition in which seeds are produced without fertilization is called apomixis. It is a kind of asexual reproduction, but it mimics sexual reproduction. There are several mechanisms for apomixis. One of them is seen in citrus and mango fruits. In this case, the nucellus begins to divide and intrude into the embryo sac. It eventually develops into a seed. Since the nucellus is composed of diploid cells, the embryo sac in such a case has diploid cells.
It is also important to recall that fertilization cannot happen in the cells which were not formed after meiosis. Moreover, haploid cells are never involved in apomixes. It is the diploid cells which bring about apomixes. Hence, embryo sacs apomictic species appear normal but contain diploid cells.

NCERT Exemplar Class 12 Solutions Subject Wise

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Approach to solve of Class 12 Biology Chapter 2 questions

Provided below are some of the key steps by which students can solve the questions of this chapter effectively and easily.

1. Important terms such as microsporogenesis, megasporogenesis, pollination, and double fertilisation need to be understood thoroughly.

2. Practice labelled diagrams like the structure of anther, ovule, pollen grain, embryo sac, as they help in giving the explanation.

3. Flowcharts or bullet points can be used to learn the sequence of events, such as flower development → gamete formation → pollination → fertilisation → seed & fruit formation.

4. The NCERT textbook needs to be read in detail, as some questions are directly based on it.

5. Practice MCQs, short and long answer type questions to get an understanding of the question pattern and how to solve them effectively.

Also, read the NCERT Solution subject-wise

Important Topics of Class 12 Biology Chapter 2

This chapter explains how plants reproduce and covers key topics like pollination, fertilisation, and seed formation. Some important points are listed below for easy understanding.

Flower Parts: Sepals, petals, stamens, carpels, and their functions in reproduction.
Pollen Formation: Microsporogenesis: the development of pollen grains in the stamen, including the role of the tapetum.
Egg Formation: Megasporogenesis: the development of the embryo sac and egg inside the ovule.
Pollination: The transfer of pollen from the stamen to the carpel, including types (self, cross) and agents.
Fertilisation: Double fertilisation: the fusion of sperm with the egg and the formation of the endosperm.
Seed Development: The development of the ovule into a seed, including the role of the endosperm and the processes of dormancy and germination.
Fruit Development: The development of the ovary into a fruit, including true fruits, false fruits, and parthenocarpy.
Plant Breeding: Techniques such as emasculation and bagging are used to control pollination and create new plant varieties.
Apomixis/Polyembryony: Asexual reproduction through seeds and the formation of multiple embryos in a single seed.
Parthenocarpy: The development of fruit without fertilisation, resulting in seedless fruits.

Also, check the NCERT Books and the NCERT Syllabus here

Important Question from NCERT Exemplar Class 12 Biology Chapter 2

Here is an important question, which is carefully selected to help you focus on key concepts and help in your exam preparation.

Question: The generative cell was destroyed by a laser, but a normal pollen tube was still formed because?

A. The vegetative cell is not damaged.

B. Contents of killed generative cells stimulate pollen growth.

C. The laser beam stimulates the growth of the pollen tube.

D. The region of emergence of the pollen tube is not harmed.

Answer: The correct answer is option 1. The vegetative cell is not damaged.

Explanation:

Pollen grain or microspores divide mitotically, forming a larger tube or vegetative cell and a small generative cell. Since vegetative cells give rise to pollen tubes and the generative cell divides to form two male gametes, if a generative cell is destroyed by a laser, a normal pollen tube will still form through the vegetative cell, which is undisturbed.

Must Read NCERT Notes subject-wise

NCERT Exemplar Class 12 Biology Chapter Wise Links

Explore all the chapter-wise links of Biology to strengthen your understanding and boost exam confidence.

NCERT Exemplar Class 12 Biology Chapter 1 Reproduction In Organisms

NCERT Exemplar Class 12 Biology Chapter 2 Sexual Reproduction In Flowering Plants

NCERT Exemplar Class 12 Biology Chapter 3 Human Reproduction

NCERT Exemplar Class 12 Biology Chapter 4 Reproductive Health

NCERT Exemplar Class 12 Biology Chapter 5 Principles of Inheritance And Variation

NCERT Exemplar Class 12 Biology Chapter 6 Molecular Basis of Inheritance

NCERT Exemplar Class 12 Biology Chapter 7 Evolution

NCERT Exemplar Class 12 Biology Chapter 8 Human Health and Disease

NCERT Exemplar Class 12 Biology Chapter 9 Strategies For Enhancement in Food Reproduction

NCERT Exemplar Class 12 Biology Chapter 10 Microbes in Human Welfare

NCERT Exemplar Class 12 Biology Chapter 11 Biotechnology: Principles and Processes

NCERT Exemplar Class 12 Biology Chapter 12 Biotechnology and Its Applications

NCERT Exemplar Class 12 Biology Chapter 13 Organisms and Populations

NCERT Exemplar Class 12 Biology Chapter 14 Ecosystems

NCERT Exemplar Class 12 Biology Chapter 15 Biodiversity and Conservation

NCERT Exemplar Class 12 Biology Chapter 16 Environmental Issues

Frequently Asked Questions (FAQs)

Q: How is double fertilization unique to angiosperms?

Double fertilization involves:

First fusion: One sperm + egg → diploid zygote.
Second fusion: Second sperm + polar nuclei → triploid endosperm (nutritive tissue).
This ensures embryo nourishment and is exclusive to flowering plants

Q: What are the post-fertilization changes in a flower?

Ovary → Fruit
Ovules → Seeds
Petals and sepals wither and fall off
Zygote develops into an embryo

Q: What are the important questions from Chapter 2 of NCERT Exemplar Class 12 Biology?

Key topics include:

Male and female reproductive systems
Gametogenesis (spermatogenesis and oogenesis)
Menstrual cycle stages and hormonal regulation
Fertilization process and embryo development
Role of the placenta and parturition

Q: How does pollination occur in flowering plants?

Pollination involves pollen transfer from anther to stigma via agents like insects, wind, or water.
Process:

Hydration: Pollen rehydrates on stigma.
Germination: Pollen tube grows through the style.
Fertilization: Sperm cells travel via the tube to fuse with the ovule

Q: What is the difference between self-pollination and cross-pollination?

Self-Pollination	Cross-Pollination
Pollen transfers to the same flower/plant	Pollen transfers to another plant
No external agents required	Requires pollinators (e.g., insects, wind)
Reduces genetic diversity	Enhances genetic diversity
Example: Peas, sunflowers	Example: Apples, strawberries

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Questions related to CBSE Class 12th

On Question asked by student community

Have a question related to CBSE Class 12th ?

12th Exam 2025Kitin tareekh ko hoga

Hello,

The date of 12 exam is depends on which board you belongs to . You should check the exact date of your exam by visiting the official website of your respective board.

Hope this information is useful to you.

Read Complete Answer

Nidhi Raghuwanshi

21 Sep'25

12th biology question paper 2023-2025

Hello,

Class 12 biology questions papers 2023-2025 are available on cbseacademic.nic.in , and other educational website. You can download PDFs of questions papers with solution for practice. For state boards, visit the official board site or trusted education portal.

Hope this information is useful to you.

Read Complete Answer

Nidhi Raghuwanshi

21 Sep'25

In March 2025, I passed the CBSE 12th board and gave KCET. I am taking a drop year. I will reappear in the CBSE board exam in the upcoming 2026 exam in February as a private candidate to increase my PCM aggregate, as KCET gives 50% weightage to PCM aggregate, and I will also give the KCET exam. So, to calculate rank, do they use the board marksheet from 2025 or 2026? Also for each subject will best out of two marks accross both the marksheets be considered? #kcet

Hello Pruthvi,

Taking a drop year to reappear for the Karnataka Common Entrance Test (KCET) is a well-defined process. As a repeater, you are fully eligible to take the exam again to improve your score and secure a better rank for admissions.

The main procedure involves submitting a new application for the KCET through the official Karnataka Examinations Authority (KEA) website when registrations open for the next academic session. You must pay the required application fee and complete all formalities just like any other candidate. A significant advantage for you is that you do not need to retake your 12th board exams. Your previously secured board marks in the qualifying subjects will be used again. Your new KCET rank will be calculated by combining these existing board marks with your new score from the KCET exam. Therefore, your entire focus during this year should be on preparing thoroughly for the KCET to achieve a higher score.

For more details about the KCET Exam preparation, CLICK HERE.

I hope this answer helps you. If you have more queries, feel free to share your questions with us, and we will be happy to assist you.

Thank you, and I wish you all the best in your bright future.

Read Complete Answer

Ark Pandey

20 Sep'25

I'm studying scince in karnatakastate board, can i take commerce in cbse for 12th next year?

Yes, you can switch from Science in Karnataka State Board to Commerce in CBSE for 12th. You will need a Transfer Certificate from your current school and meet the CBSE school’s admission requirements. Since you haven’t studied Commerce subjects like Accountancy, Economics, and Business Studies, you may need to catch up before or during 12th. Not all CBSE schools accept direct admission to 12th from another board, so some may ask you to join Class 11 first. Make sure to check the school’s rules and plan your subject preparation.

Read Complete Answer

Abhilasha Agrawal

18 Sep'25

12th class cbse boards most important que ans ans in hindi midum subject hindi impotent question jo exam main aaynge wo btai

Hello

For the 12th CBSE Hindi Medium board exam, important questions usually come from core chapters like “Madhushala”, “Jhansi ki Rani”, and “Bharat ki Khoj”.
Questions often include essay writing, letter writing, and comprehension passages. Grammar topics like Tenses, Voice Change, and Direct-Indirect Speech are frequently asked.
Students should practice poetry questions on themes and meanings. Important questions also cover summary writing and translation from Hindi to English or vice versa.
Previous years’ question papers help identify commonly asked questions.
Focus on writing practice to improve handwriting and presentation. Time management during exams is key to answering all questions effectively.

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Option 1) $0.34\; J$	Option 2) $0.16\; J$
Option 3) $1.00\; J$	Option 4) $0.67\; J$

Option 1) $2,000 \; J - 5,000\; J$	Option 2) $200 \, \, J - 500 \, \, J$
Option 3) $2\times 10^{5}J-3\times 10^{5}J$	Option 4) $20,000 \, \, J - 50,000 \, \, J$

Option 1) $K/2\,$	Option 2) $\; K\;$
Option 3) $zero\;$	Option 4) $K/4$

Option 1) $11.2\, L\, H_{2(g)}$ at STP is produced for every mole $HCL_{(aq)}$ consumed	Option 2) $6L\, HCl_{(aq)}$ is consumed for ever $3L\, H_{2(g)}$ produced
Option 3) $33.6 L\, H_{2(g)}$ is produced regardless of temperature and pressure for every mole Al that reacts	Option 4) $67.2\, L\, H_{2(g)}$ at STP is produced for every mole Al that reacts .

Option 1) 0.02	Option 2) 3.125 × 10^-2
Option 3) 1.25 × 10^-2	Option 4) 2.5 × 10^-2

Option 1) decrease twice	Option 2) increase two fold
Option 3) remain unchanged	Option 4) be a function of the molecular mass of the substance.

Option 1) Molality	Option 2) Weight fraction of solute
Option 3) Fraction of solute present in water	Option 4) Mole fraction.

Option 1) twice that in 60 g carbon	Option 2) 6.023 × 10²²
Option 3) half that in 8 g He	Option 4) 558.5 × 6.023 × 10²³

Option 1) less than 3	Option 2) more than 3 but less than 6
Option 3) more than 6 but less than 9	Option 4) more than 9

NCERT Exemplar Class 12 Biology Solutions Chapter 2 Sexual Reproduction in Flowering Plants

Find Answers of NCERT Exemplar for Class 12 Science Chapter 2 (Multiple Choice Questions)

Get Answers to Class 12 Science Chapter 2 NCERT Exemplar (Very Short Answer Questions)

Access Answers to NCERT Exemplar Class 12 Chapter 2 Sexual (Short Answer Questions)

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