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 provides meticulously detailed NCERT Solutions that align with the latest CBSE curriculum. Our expert biology faculty has designed these solutions to simplify complex botanical diagrams and terminology into easy-to-understand, step-by-step explanations. By utilizing ALLEN’s resources, students can master labeling and theoretical concepts with precision. These solutions are crafted to help you build a strong conceptual foundation, ensuring you are fully prepared for both your board exams and competitive medical challenges.
1.0Download NCERT Solutions Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants : Free PDF
This chapter explains how flowers produce gametes, how pollination occurs, and how fertilisation leads to seed and fruit formation. The NCERT Solutions for Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants help students revise key stages and practise textbook questions easily. Download the free PDF now to study anytime and prepare confidently for exams.
2.0Class 12 Biology Chapter 1: Key Concepts
The focus of this chapter is on understanding the reproductive structures and the processes in the reproduction of flowering plants. Some of the key lessons covered in this chapter are given below:
- Structure of a Flower: Understanding different parts like sepals, petals, stamens, and carpels and their roles in reproduction of a flowering plant.
- Microsporogenesis and Megasporogenesis: Learn the formation of pollen grains and embryo sacs along with their involvement in the reproductive process of plants.
- Gametophytes: Studying the development of male and female gametophytes in flowering plants.
- Pollination: Understanding what pollination is, what are the types of pollination and the role of different agents like insects, wind, and water in the process of reproduction.
- Fertilisation: Learning about double fertilisation and how it is significant in angiosperms.
- Development of Seed and Fruit: Understanding how the zygote and ovary develop after fertilisation.
- Apomixis and Polyembryony: Learning about special reproductive processes in plants.
3.0NCERT Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants : Detailed Solutions
1. Name the parts of an angiosperm flower in which development of male and female gametophyte take place.
Ans: The parts of an angiosperm flower where the development of male and female gametophytes takes place are given below:
- Male Gametophyte: Development occurs inside the Anther (specifically within the pollen sacs or microsporangia). The pollen grain represents the male gametophyte.
- Female Gametophyte: Development occurs inside the Ovule (specifically within the nucellus). The embryo sac represents the female gametophyte.
2. 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.
Ans:
- The structures formed at the end of these two events are:
- End of Microsporogenesis: Microspores (which develop into pollen grains).
- End of Megasporogenesis: Megaspores (the functional one develops into the embryo sac).
3. Arrange the following terms in the correct developmental sequence:
Pollen grain, sporogenous tissue, microspore tetrad, pollen mother cell, male gametes.
Ans: The correct developmental sequence is:
- Sporogenous tissue - The initial diploid tissue in the young anther
- Pollen mother cell - Cells of the sporogenous tissue that differentiate
- Microspore tetrad - Result of meiosis in the pollen mother cell
- Pollen grain - Developed microspore after maturation and dehydration
- Male gametes - Formed inside the pollen grain via mitosis of the generative cell
4. With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.
Ans:
A typical angiosperm ovule (Anatropous) consists of:
- Funicule: The stalk attaching the ovule to the placenta.
- Hilum: The junction where the body of the ovule fuses with the funiculus.
- Integuments: Protective envelopes (outer and inner) surrounding the nucellus.
- Micropyle: A small opening at the tip where the integuments are absent; the site of pollen tube entry.
- Chalaza: The basal part of the ovule, opposite the micropyle.
- Nucellus: Mass of parenchymatous cells containing reserve food.
- Embryo Sac: The female gametophyte located within the nucellus.
5. What is meant by monosporic development of female gametophyte?
Ans. In most angiosperms, out of the four megaspores formed after meiosis, three of them degenerate and only one remains functional. This single functional megaspore will develop into the female gametophyte (embryo sac). This method of embryo sac formation is called monosporic development.
6. With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.
Ans: The nucleus of the functional megaspore undergoes three sequential mitotic divisions resulting in 8 nuclei. They are arranged as follows:
Egg Apparatus (Micropylar end): 3 cells (2 Synergids + 1 Egg cell).
Antipodals (Chalazal end): 3 cells.
Central Cell: 1 large cell containing 2 Polar Nuclei.
Total: 7 Cells (3+3+1) and 8 Nuclei (3+3+2).
7. What are chasmogamous flowers? Can cross-pollination occur in cleistogamous flowers? Give reasons for your answer.
Ans:
- Chasmogamous flowers: Flowers containing exposed anthers and stigma are called Chasmogamous flowers
- Cleistogamous flowers: No, cross-pollination cannot occur because these flowers never open. The anthers and stigma lie close to each other, resulting in self pollination.
8. Mention two strategies evolved to prevent self-pollination.
Ans:
- Dichogamy: Is a condition where the pollen release and stigma receptivity are not synchronized. One matures before the other to prevent self pollination.
- Self-incompatibility: It is a genetic mechanism that prevents self-pollen from fertilizing ovules by inhibiting pollen germination or tube growth.
9. What is self-incompatibility? Why does self-pollination not lead to seed formation in these species?
Ans: Self-incompatibility is a genetic mechanism that prevents "self" pollen (pollen from the same flower or plant) from fertilizing the ovule. It does not lead to seed formation because the plant recognizes the pollen as its own and prevents syngamy by blocking the pollen tube growth in the pistil.
10. What is bagging technique? How is it useful in a plant breeding programme?
Ans: Bagging technique is the covering of a female flower after emasculation with a bag to prevent contamination of the stigma by unwanted foreign pollen.
Adopting this method ensures that only the desired pollen grains are used for pollination in artificial hybridization.
11. What is triple fusion? Where and how does it take place? Name the nuclei involved in triple fusion
Ans:
Definition: The fusion of one male gamete with two polar nuclei (or a secondary nucleus).
Location: Inside the Central Cell of the embryo sac.
Nuclei involved: One haploid male gamete (n) + two haploid polar nuclei (n+n). This forms the triploid Primary Endosperm Nucleus (3n).
12. Why do you think the zygote is dormant for sometime?
Ans: The zygote waits for the endosperm to begin developing. Since the endosperm provides the necessary nutrition for the growing embryo, the zygote remains dormant until sufficient food reserves are established.
13. Differentiate between:
(a) Hypocotyl vs. Epicotyl: Hypocotyl is the portion of the embryonal axis below the cotyledons (ends in radicle); Epicotyl is the portion above the cotyledons (ends in plumule).
(b) Coleoptile vs. Coleorrhiza: Coleoptile protects the young shoot (plumule); Coleorrhiza protects the young root (radicle) in monocots.
(c) Integument vs. Testa: Integument is the protective layer of the ovule; Testa is the outer protective layer of the seed (formed from the integument).
(d) Perisperm vs. Pericarp: Perisperm is the persistent residual nucellus in a seed (e.g., black pepper); Pericarp is the wall of the fruit developed from the ovary wall.
14. Why is apple called a false fruit? Which part(s) of the flower forms the fruit?
Ans. Apple is a "false fruit" because the fruit develops from the thalamus rather than the ovary. In "true fruits," only the ovary participates in fruit formation.
15. What is meant by emasculation? When and why does a plant breeder employ this technique?
Ans. Emasculation is the removal of anthers from a bisexual flower bud before they dehisce using forceps.
When/Why: Used by plant breeders to prevent self-pollination, allowing them to cross-pollinate the flower with desired pollen.
16. If one can induce parthenocarpy through the application of growth substances, which fruits would you select to induce parthenocarpy and why?
Ans. I would select fruits where seeds are undesirable for consumption or processing, such as Grapes, Bananas, or Oranges. Seedless varieties have higher commercial value and are easier to eat.
17. Explain the role of tapetum in the formation of pollen-grain wall.
Ans. The tapetum provides nourishment to developing microspores. It secretes Sporopollenin, the most resistant organic material, which forms the outer layer of the pollen wall, also known as the exine.
18. What is apomixis and what is its importance?
Ans. Apomixis is a form of asexual reproduction that mimics sexual reproduction by producing seeds without fertilization.
Importance: In agriculture, if hybrid seeds are made apomictic, farmers can keep using the seeds from their harvest year after year without the hybrid characters segregating (splitting), saving them the cost of buying expensive hybrid seeds every season.
4.0Key Features of NCERT Solutions for Class 12 Biology Chapter 1
- The NCERT Solutions helps in understanding reproductive stages clearly, helping students follow complex life cycle processes step by step.
- Practice questions strengthen understanding of labelled diagrams and fertilisation pathways.
- The answers from the solutions are in line with the latest NCERT syllabus and match the CBSE board exam pattern.
- Regular revision of these solutions improves recall of terms that are technical and sequence-based biological events.
- Developing strong fundamentals support preparation for NEET and advanced studies in biology.
- Provision of clear explanations can help students connect plant reproduction with concepts like crop production and biodiversity.
