NCERT Solutions explain each answer in a clear and simple way, helping students understand processes like pollination, fertilisation, and seed formation so they can write correct, well-structured answers in exams.
Yes, they focus on correct terminology and clear definitions, which is important for scoring full marks in theory-based questions.
They guide students on how to label and explain important diagrams such as the structure of the flower, pollen grain, and embryo sac.
Yes, every end-of-chapter question from the prescribed NCERT textbook is answered in these solutions.
Double fertilisation is a characteristic feature of flowering plants in which one male gamete fuses with the egg to form a zygote, while the other fuses with the polar nuclei to form the primary endosperm nucleus.
Self-pollination transfers pollen to the stigma of the same flower or another flower on the same plant, while cross-pollination transfers pollen between flowers of different plants of the same species.
After fertilisation, the zygote develops into an embryo, the ovules develop into seeds, and the ovary develops into a fruit.
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NCERT Solutions Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants
Sexual Reproduction in Flowering Plants is the first chapter of Class 12 Biology. In this chapter, students learn about how flowering plants reproduce, the structure of flowers, formation of male and female gametes, pollination, fertilisation, and the development of seeds and fruits. It also helps students understand how genetic material is transferred from one generation to the next and how plants maintain diversity through sexual reproduction.
ALLEN offers highly detailed NCERT Solutions which are based on the latest CBSE curriculum. Our expert biology faculty have designed these solutions to make the complex botanical diagrams and terminology easy with the stepwise explanation. ALLEN’s resources help students learn the art of labelling and theoretical concepts with precision. These solutions are aimed at providing you with a strong understanding of concepts and preparing you for your board exams and competitive medical entrance exams.
1.0Key Concepts of Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants
This chapter explains the reproductive structures of flowering plants and the different stages involved in sexual reproduction. The important concepts covered in Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants include:
Structure of a Flower: Understand the main parts of a flower, including sepals, petals, stamens, and carpels, and learn their roles in plant reproduction.
Microsporogenesis and Megasporogenesis: Learn how pollen grains and embryo sacs are formed and understand their importance in the reproductive process.
Male and Female Gametophytes: Study the development and structure of male and female gametophytes in flowering plants.
Pollination: Understand the meaning and types of pollination, along with the role of agents such as insects, wind, and water in transferring pollen grains.
Fertilisation: Learn about fertilisation in flowering plants, including the process of double fertilisation and its importance in angiosperms.
Development of Seed and Fruit: Understand how the zygote develops into an embryo and how the ovary develops into a fruit after fertilisation.
Apomixis and Polyembryony: Learn about these special reproductive processes and understand their importance in seed formation and plant reproduction.
2.0NCERT Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants : Detailed Solutions
Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
Ans. Development of male and female gametophytes takes place in anther and ovary, Respectively.
Differentiate between microsporogenesis and megasporogenesis. Which type of cell division occurs during these events? Name the structures formed at the end of these two events.
Microsporogenesis
Megasporogenesis
In this process, haploid microspore are formed from diploid mother cell or pollen mother cells (MMC or PMC).
In this process, haploid megaspore are formed from diploid mother cell (MMC).
It occurs inside the microsporangium or pollen sac of an anther.
It occurs inside the nucellus of ovule or megasporangium.
There are many microspore mother cells in a microsporangium.
There are generally a single megaspore mother cell in a megasporangium.
The four microspore formed from a single microspore mother cell are generally arranged in a tetrahedral structure.
The four megaspore formed from a megaspore mother cells are arranged in the form of a linear tetrad.
All the four mircrospore arranged in a tetrahedral tetrad are functional.
Only one megaspore remains functional while the other three degenerates.
The microspores give rise to male gametophytes.
The functional megaspore gives rise to female gametophytes.
Meiosis occurs during micro and megasporogenesis. Microspores (pollen grains) are formed at the end of microsporogenesis and female gametophyte (embryo sac) are formed at the end of megasporogenesis.
Arrange the following terms in the correct developmental sequence: pollen grain, sporogenous tissue, microspore tetrad, pollen mother cell, male gametes.
Ans. Sporogenous tissue-Pollen mother cell - Microspore tetrad-Pollen grain-Male gametes.
With a neat, Labelled diagram, describe the parts of a typical angiosperm ovule.
Ans. The ovule is a small structure attached to the placenta by means of a stalk called funicle. The body of the ovule fuses with funicle in the region called hilum. Thus, hilum represents the junction between ovule and funicle. Each ovule has one or two protective envelopes called integuments. Integuments encircles the nucellus except at the tip where a small opening called the micropyle is organized. Opposite a micropylar end, is the chalaza, representing the basal part of the ovule.
What is meant by monosporic development of a female gametophyte?
Ans. Out of the four megaspores, three degenerate and only one remains functional which develops into a female gametophyte or embryo sac. This is called monosporic development i.e. when embryo sac develops from one single megaspore it is called monosporic embryo sac.
With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
[IMP.]
Ans. Female gametophyte or embryo sac is a small oval structure that contains a 3-celled egg apparatus, 3 antipodal cells and one binucleate central cell hence it is 7 - celled and 8 - nucleate structure.
(a) Egg apparatus: It consists of two synergids and an egg cell towards the micropylar end. The cells of egg apparatus are uninucleate. Synergids towards its micropylar end have cellular thickenings called filiform apparatus that helps in guiding the pollen tubes into the synergids
(b) Antipodal cells: Chalazal end of embryo sac contain three cells of various shapes and sizes called antipodal cells.
(c) Central cell: It is the single and largest cell which is bounded by a membrane of embryo sac. It contains two polar nuclei which later fuse to form diploid secondary nucleus. After fertilisation the central cell gets converted into triploid primary endosperm cell (PEC) which forms endosperm.
What are chasmogamous flowers? Can crosspollination occur in cleistogamous flowers? Give reasons for your answer.
Ans. Chasmogamous flowers are open flowers with exposed stamens and stigma which facilitate cross pollination. No cross-pollination occurs in cleistogamous flowers as these flowers are closed and never open and thus no transfer of pollen from outside to stigma of the flower is possible.
Mention two strategies evolved to prevent selfpollination in flowers.
Ans.
(i) Maturation of anthers and stigma at different time periods in a bisexual flower prevents self pollination (dichogamy).
(ii) Production of unisexual flowers.
What is self-incompatibility? Why does selfpollination not lead to seed formation in selfincompatible species?
Ans. Self-incompatibility or self sterility is the inability of an intersexual or bisexual plant to produce viable seeds on self-pollination in spite of producing functional male and female gametes. Since fertilization does not take place, no seeds are produced. It is a genetic mechanism that prevents self pollen from fertilizing ovules by inhibiting pollen tube growth in pistil.
What is bagging technique? How is it useful in a plant breeding Programme ?
Ans. Bagging technique is the process of covering the emasculated flower with a butter paper bag to prevent contamination from unwanted (foreign) pollen.
Use in plant breeding : It ensures that only desired pollen grains are used of for pollination, thus helping in controlled hybridisation.
What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion.
Ans. Triple fusion is fusion of one male gamete and two polar nuclei (or secondary nucleus if the two have already fused) in the central cell of embryo sac to form primary endosperm nucleus. It takes place in the central cell of an embryo sac. Three nuclei are involved in triple fusion i.e. nuclei in the central cell one male nucleus and two polar nuclei in the central cell.
Why do you think the zygote is dormant for sometime in a fertilised ovule?
Ans. The zygote is dormant for sometime in a fertilised ovule because the embryo which is developed from zygote may obtain from endosperm.
Differentiate between: [IMP.]
(a) Hypocotyl and Epicotyl;
(b) Coleoptile and Coleorrhiza
(c) Integument and Testa;
(d) Perisperm and Pericarp
Ans.
(a) Hypocotyl and Epicotyl
Hypocotyl
Epicotyle
The region of the embryonal axis that lies between the radical and the point of attachment of cotyledons is called as hypocotyle.
The region of the embryonal axis that lies between the plumule and cotyledons is called as epicotyle.
Hypocotyle pushes the seed above the soil in epigeal germination.
Epicotyle pushes the plumule above the soil in hypogeal germination.
It is an important component of embryonic root system.
It is an important component of embryonic shoot system.
(b) Coleoptile and Coleorrhiza
Coleoptile
Coleorrhiza
The shoot apex and few leaf Primordia are enclosed in a hollow foliar structure in epicotyl region in monocots and is called coleoptiles.
The radical and root cap are situated at the lower end of embryonal axis are enclosed by undifferentiated sheath called coleorrhiza.
It emerges from the soil turns green and carries out photosynthesis.
It remains in the soil and is non-green in colour.
Integument
Testa
It is part of prefertilization events.
It is part of postfertilization events.
It is the protective covering of the ovule may differentiate into inner and outer integument.
It is the protective outer covering of the seed formed from outer integument.
It is thin and living in nature.
It is thick and dead in nature.
(d) Perisperm and Pericarp
Perisperm
Pericarp
It represent persistent remains of nucellus in the seed.
It represent the wall of fruit formed by the ovarian wall.
It is a part that belongs to seed.
It is a part that belongs to fruit.
It is usually dry.
It can be dry or fleshy.
Why is apple called a false fruit? Which part (s) of the flower forms the fruit?
Ans. False fruits are those fruits in which accessory floral parts also contribute to fruit formation. In apple, the thalamus also contributes to fruit formation. Therefore, it is called a false fruit. The fruit develops from the ovary of the flower.
What is meant by emasculation? When and why does a plant breeder employ this technique?[IMP.]
Ans. Emasculation is a practice of removal of stamens/anthers before the anther dehiscence from bisexual flowers in female parent. A plant breeder employs this technique in the immature bud condition before the anthers begin to differentiate. It is required to prevent self-pollination. Uses in plant breeding :
(i) Prevention of contamination and pollination of stigma of female flowers with foreign undesirable pollens.
(ii) Prevention of damage by animals.
If one can induce parthenocarpy through the application of growth substances, which fruits would you select to induce parthenocarpy and why?
Ans. Only fleshy fruits like orange watermelon, lemon, etc. should be selected as parthenocarpic fruit. In these fruits are irritant during consumption of seeds the fruits even more valuable. It is easy to make fruit juices, jams, etc. with seedless fruits, which increases their commercial value.
Explain the role of tapetum in the formation of pollen-grain wall.
Ans. Tapetum is the innermost wall layer of a microsporangium. It nourishes the developing pollen grains and also help in the formation of wall of pollen grains. The cells of tapetum secrete Ubisch granules that provide sporopollenin and other materials for exine formation.
What is apomixis and what is its importance?
Ans. Apomixis is a type of asexual reproduction that mimics sexual reproduction to form seeds without fertilisation. In apomictic seeds, the parental characters are maintained in the progeny/offspring as there is no meiosis or segregation of characters. If desired hybrid seeds are made apomictic, farmers can continue to use these seeds to raise new crops year after year without losing the hybrid characters.
3.0NCERT Solutions for Class 12 Biology | Other Chapter-wise Links
Find chapter-wise NCERT Solutions for Class 12 Biology for all other chapters through the links given below.
