RBSE Solutions For Class 12 Biology Chapter 2: Male and Female Gametophyte Structure and Development | Textbook Important Questions & Answers

RBSE Class 12 Biology Chapter 2- Male and Female Gametophyte Structure and Development provide complete information related to the structure and development of male and female gametophyte. It also includes a detailed explanation of stamen, pollen grains, the structure of pollen grains, microsporogenesis, megasporogenesis, the formation of male and female gametes, structure, functions and types of the ovule. These important questions help students to perform best in their exams. By practising these important questions, students can analyse their preparation.

The Rajasthan Board Class 12 Biology Chapter 2 important questions is the best study material for revisions and last-minute preparations. By practising these important questions, students can gain in-depth knowledge about the topic and also help students by providing a strategy to prepare for various board examinations and also for medical exams.

RBSE Class 12 Biology Chapter 2 Important Textbook Questions & Solutions

RBSE Biology Chapter 2: MCQs Type Textbook Questions & Solutions

Q.1.Which of the following statements are true?

(a)Formation of male and female gametes is called Microgametogenesis.

(b)Formation of male and female gametes is called Megasporogenesis.

(c)Formation of male and female gametes is called Microsporogenesis.

(d)Formation of male and female gametes is called Gametogenesis.

Sol: (d)Formation of male and female gametes is called Gametogenesis.

Q.2.________ is the female reproductive organ in seed plants.

(a)Pollen tube.

(b)Anthers.

(c)Stigma.

(d)Ovule.

Sol: (d)Ovule.

Q.3.Pollen is produced by the ______.

(a)Pollen tube.

(b)Anthers.

(c)Stigma.

(d)Ovary.

Sol: (b) Anthers.

Q.4.How many cells does a matured pollen grain contain?

(a)One cell.

(b)Many cells.

(c)Two cells.

(d)None of the above.

Sol: (c)Two cells.

Q.5. Based on their shapes, ovules have been separated into______categories.

(a)Six.

(b)Five.

(c)Seven.

(d)Three.

Sol: (a)Six.

Q.6.Formation of seeds requires ______.

(a) Pollination.

(b) Fertilization.

(c) Gametogenesis.

(d) Megasporogenesis.

Sol: (a)Pollination.

Q.7. Embryo sac is located inside the________.

(a)Pollen tube.

(b)Anthers.

(c)Ovule.

(d)Stigma.

Sol: (c)Ovule

Q.8. How many types of microspore tetrads are there?

(a)One.

(b)Three.

(c)Five.

(d)Seven.

Sol: (c)Five.

Q.9. Which of the following is the innermost layer of the anther?

(a)Embryo.

(b)Tapetum.

(c)Ovule.

(d)Nucellus.

Sol: (b)Tapetum.

Q.10. Which of the following statements are true?

(a)25 meiotic cell divisions are required to form 100 pollen grains.

(b)50 meiotic cell divisions are required to form 100 pollen grains.

(c)100 meiotic cell divisions are required to form 100 pollen grains.

(d)75 meiotic cell divisions are required to form 100 pollen grains.

Sol: (a)25 meiotic cell divisions are required to form 100 pollen grains.

Q.11. Functional mega spore in a flowering plant develops into________.

(a)Embryo sac.

(b)Embryo.

(c)Ovule.

(d)Endosperm.

Sol: (a) Embryo sac.

Q.12.Germinated pollen grains are known as ________.

(a)Female Gametophyte.

(b)Pollen grain.

(c)Male Gametophyte.

(d)None of the above.

Sol: (c)Male Gametophyte.

Q.13. How many male gametes are formed from a pollen grain in angiosperms?

(a)One.

(b)Two.

(c)Three.

(d)Four.

Sol: (b)Two

Q.14. The Ubisch body is formed by ______.

(a)Tapetum.

(b)Epidermis.

(c)Endothecium.

(d)Integument.

Sol: (a)Tapetum

Q.15. How many cells and nuclei do a mature polygonum type of embryo have?

(a)Seven cells and seven nuclei.

(b)Eight cells and eight nuclei.

(c)Seven cells and eight nuclei.

(d)Eight cells and seven nuclei.

Sol: (c)Seven cells and eight nuclei.

Q.16.Which of the following is the function of Tapetum – the innermost layer of the anther?

(a)Producing pollen grains.

(b)Providing nutrition.

(c)Producing egg cells.

(d)Fertilization.

Sol: (b)Providing nutrition.

Q.17.Which of the following plant structures develops into a seed when fertilized.

(a)Egg cell.

(b)Ovule.

(c) Pollen.

(d)Sperm cells.

Sol: (b)Ovule.

Q.18.Which of the following represents female gametophyte in angiosperms?

(a)Embryo.

(b)Nucellus.

(c) Endosperm.

(d)Embryo sac.

Sol: (d)Embryo sac.

Q.19. The female reproductive part of a flower is ________.

(a)Pistil.

(b)Anther.

(c) Stigma.

(d)Androecium.

Sol: (a)Pistil.

Q.20. Which of the following are called as the first cell of the male gametophyte?

(a)Egg cell.

(b)Microspore.

(c) Pollen.

(d)Sperm cells.

Sol: (b)Microspore.

RBSE Biology Chapter 2: Short Answer Type Questions.

Q.1. What is Pollen kit?

Sol. A sticky, oily and yellow coloured layer present on the exine or outermost layer of the pollen grain is called the pollen kit.It is also called a pollen coat and is made up of lipids and carotenoids, which is secreted by tapetum. Pollen kits are especially found in those plants where the process of pollination is distributed by insects. Pollen kits are present in rose, sunflower, lotus, etc.

Q.2.What is Microsporangium?

Sol: Microsporangium is a structure in the plant’s male reproductive organ where the development of the pollen takes place. The structure of the microsporangium appears to have a circular outline and is surrounded by four layers:

  1. Epidermis.
  2. Endothecium.
  3. Middle layers.
  4. Tapetum.

Q.3.What is megasporogenesis?

Sol: Megasporogenesis is the process of arrangement of megaspores from a megaspore mother cell. The megaspore mother cell divides meiotically. One of the three megaspores is utilized while the other three degenerate. The functional megaspore forms the female gametophyte. The complete process occurs inside the ovules.

Q.4.What is the egg apparatus?

Sol. The apparatus, which is located at the end of the embryo sac closer to the micropyle in the seed-bearing plant, is called the egg apparatus. This apparatus consists of an egg and two sterile cells. Hence the name is referred to as egg apparatus.

Q.5. What is anther dehiscence?

Sol: The process of bursting the walls of the wholly matured pollen is termed as anther dehiscence. This process occurs in four different methods:

  1. Transverse Dehiscence.
  2. Longitudinal Dehiscence.
  3. Porous Dehiscence.
  4. Septal Dehiscence.

Q.6. Explain the structure of a mature embryo sac, along with a neat labelled diagram.

Sol: The embryo sac is the female gametophyte of an angiosperm. It is an oval-shaped structure present in the ovule of flowering plants.

Embryo Sac

Embryo Sac

The features of a typical mature embryo sac of Angiosperms is

  1. It is a 7-celled and 8-nucleate structure.
  2. At the micropylar end, an egg apparatus is present, which consists of an egg cell and 2 synergid cells.
  3. The synergids contain filiform apparatus, which guides the entry of the pollen tube into the embryo sac during fertilisation.
  4. At the chalazal end, three antipodal cells are present.
  5. In the centre, two polar nuclei are present which get fused prior to fertilisation to form a diploid secondary nucleus.

Therefore, eight nuclei are constituted within seven cells. Thus, embryo sac is 7-celled and 8-nucleate.

Q.7. What is the difference between pollen and pollen grain?

Sol: A pollen is defined as the mass of microspores in a male gametophyte of seed plants. It can be all pollen or single pollen grain. A pollen grain is usually defined as a unique structure composed of two cells.

Q.8. Explain how a secondary nucleus is formed?

Sol: The secondary nucleus is also known as the primary endosperm nucleus. It is a diploid nucleus formed by the fusion of two polar nuclei. During the fusion of two polar nuclei, the two sperm nuclei enter the embryo sac, where one sperm nuclei unite with the egg nucleus to form the zygote, which develops into the embryo. The other sperm nuclei combine with both of the polar nuclei and secondary nuclei are formed by their fusion.

Q.9. List out the different types of tapetum?

Sol: The tapetum is the specialised nutritive layer of cells that lines the inner wall of the pollen sac. There are two different types of tapetum and are differentiated on the basis of its behaviour.

Periplasmodial Tapetum: It is also called Amoeboid or Invasive Tapetum. These types are seen in water-plantains, lily, Alisma, Typha, etc.

Secretory Tapetum: It is also called GlandularTapetum. It is the most common type of tapetum in angiosperms.

Q.10. What is Ubisch body?

Sol: The small, acellular, spherical bodies of sporopollenin connected with the formation of exine are called the ubisch body. They are also known as orbicules and are small acellular structures of sporopollenin. The ubisch bodies are present in the tapetal cells and are just the byproducts of pollen wall sporopollenin synthesis. In angiosperms, these ubisch bodies are mainly involved in pollen development.

Q.11.What is Pollen?

Sol: Pollen is defined as the male gametophyte of gymnosperms and angiosperms. Its size ranges from 15 to 200 μm and is generally oval or spherical in shape.

Q.12.What is Megasporophyll?

Sol: A leaf-like structure, produced by heterosporous plants such as seed plants, lycophytes, and some ferns are called megasporophyll. In all seed-bearing plants, megasporophyll functions by producing megasporangia, which produce megaspores of female spores.

Q.13.Define the following term:

  1. Epidermis.
  2. Tarentum.
  3. Middle layer.

Sol:

  1. Epidermis: It is a protective outermost single-layer of angiosperms. The epidermis is involved in several functions, including the protection against water loss, regulates gas exchange, secretes metabolic compounds, etc.
  2. Tarentum: It is the innermost layer of the wall and composed of three to four layers of thin-walled cells. They are situated just below the endothelium.
  3. Middle layer: The layer situated just below the endothelium is called the middle layer. It is composed of three to four layers of thin-walled cells.

Q.14.How is a gametophyte different from sporophyte?

Sol: The main difference between gametophyte and sporophyte is that the gametophyte is the sexual phase of the plant life cycle, whereas sporophyte is the asexual phase. Another difference is that gametophytes are haploid and produced by meiosis, whereas sporophytes are diploid and produced by mitosis.

Q.15.Differentiate between Campylotropous ovule and Anatropous ovule.

Sol:

Campylotropous ovule— The body of ovule is curved and bent around so that the micropyle and chalaza do not lie in the same straight line. For example, Leguminosae.

Anatropous ovule — The body of the ovule gets completely inverted during the developmental process, such that the micropyle lies very close to hilum—for example, gamopetalae members.

Q.16. Draw the structure of the mature ovule of angiosperms.

Sol: Structure of the mature ovule of angiospermsMature Ovule

Q.17.What is microsporogenesis?

Sol: Microsporogenesis is a process, which involves the formation of microspores inside the pollen sacs of seed plants from microspore mother cells by meiotic division. This process gives rise to our haploid nuclei.

Q.18.Give the difference between Pollen grain and Ovule.

Sol:

Pollen grain Ovule
The male reproductive structure of a flower. The female reproductive structure of a flower.
Produce sperm cells. Produce egg cells.
Found in the anther of stamens. Found inside the ovary of the pistil of a flower.
Pollen grains are dispersed during pollination
by the external pollinating agents.
The ovule is not dispersed during pollination.
After the fertilization process, the pollen grains are destroyed. After the fertilization process, the Ovule develops into a seed.

Q.19.What is Circinotropous ovule?

Sol. The ovule is the female reproductive structure of a flower. A type of ovule, where the nucellus and the axis are in the same line in the beginning. Later due to the rapid growth on one side, the ovule becomes anatropous. This forms a circinotropous ovule. Opuntia is an example of a Circinotropous ovule.

Q.20.Explain the different types of ovules.

Sol: Flower is a reproductive organ of all angiosperms. It is a modified shoot and bears four main parts, which are arranged in whorls. The four different types of whorls and their members are as follows:

  1. Calyx – Their members are sepals.
  2. Corolla-Their members are petals.
  3. Androecium -Their members are stamens.
  4. Gynoecium -Their members are carpels.

RBSE Biology Class 12: Long Answer Type Questions

Q.1.What is Gametophyte? Explain in detail about the male and female gametophytes.

Sol. The gametophyte is defined as the sexual phase in the alternation of generations of plants and a few algae. This process includes both multicellular diploid generation and a multicellular haploid generation. In all plant cells, the gametophyte is involved in the production of Gametes. Ferns, hornwort and mosses are examples of gametophytes.

Structure of a Gametophyte

Structure of a Gametophytes

There are two different types of gametophytes:

  1. Male gametophytes – It is also called pollen grains. In the two-celled stage, pollen grains are released from the pollen-sacs, which further divides to form two male gametes. These male gametes are released into the embryo sac to undergo fusion with the egg and the central cell.
  2. Female gametophytes – It is also called the embryo-sac. It is the haploid stage that produces female gametes. The female gametophyte is present inside the ovule.

Q.2.Describe the structures involved in the process of gametogenesis.

Sol: Gametogenesis is the process of formation of gametes. The structures involved in the process of gametogenesis are:

  1. Microsporangium – It is also called pollen sac. It is surrounded by four walls- epidermis, endothecium, middle layers and tapetum. It is mainly responsible for the formation of the pollen grains
  2. Ovules- These are the female reproductive cells, which are responsible for the formation of female gametes. These ovules are present in the inner portion of the flower.
  3. Pollen Grains– They are minute or microscopic structures, double-walled that vary in their size. The inner wall is called the endospore and is composed of cellulose. The outer wall exospore is composed of sporopollenin.
  4. Anther- The oval-shaped or bi-lobed structure, present in the male reproductive part of a flower -stamen is called the anther. It is composed of a long tube, called a filament, and has a pollen-producing structure.
  5. Stamen- It is the male reproductive part of a flower, which consists of a stalk called the filament.

Q.3.Define the following terms:

  1. Tapetum
  2. Germ Pore
  3. Middle layer
  4. Megasporogenesis

Sol:

  1. Tapetum: The tapetum is the specialised nutritive layer of cells that lines the inner wall of the pollen sac. It is found within the anther of the flowering plant. It plays a vital role in the development of the pollen grain by providing nutrition and also serves as a precursor for the protein coat.
  2. Germ Pore: The germ pore is thin areas present in the exine regions of the pollen grains. It functions in the formation of the pollen tube and the release of the male gametes during fertilisation. In dicots, there are three germ pores and in monocots, there is only one germ pore.
  3. Megasporogenesis – It is the first phase involved in the process of female gametophyte development. In this phase, the single diploid mother cell undergoes meiosis and forms haploid megaspore tetrad out of which only one will survive and the other three disintegrate. The functional megaspore grows into an embryo sac.

Q.4. Explain the formation of Embryo Sac.

Sol: Structure of Embryo Sac

Embryo Sac

The formation of Embryo sac occurs in two stages:

Stage 1:

The first stage of the Embryo formation is called the megasporogenesis.

In this phase, the single diploid mother cell undergoes meiosis and forms haploid megaspore tetrad out of which only one will survive and other three disintegrate. The functional megaspore grows into an embryo sac.

Stage 2:

The second stage of the Embryo formation is called the megagametogenesis.

In this stage, the embryo sac is formed due to mitosis of the functional haploid megaspore to produce 8-nucleate, 7-celled gametophyte. Later the polar nuclei move to the centre out of all the eight nuclei and combine to generate a single diploid cell at that location. This single diploid cell then fuses with the sperm to generate the triploid endosperm. The other three nuclei grow into antipodal cells while two modify into synergid cells, which degenerate gradually

Q.5.Write the difference between Anatropous Ovule and Orthotropous Ovule.

Sol:

Anatropous Ovule Orthotropous Ovule
An ovule orientation in which the ovule is completely inverted in 180°. An ovule orientation in which the micropyle lies directly in line with the hilum.
Occur in both monocots and the dicot plants. Found in plants of family Polygonaceae and Piperaceae.
Both micropyle and helium come closer to each other. Both micropyle and helium lie directly in the same line.
There is a fusion of the ovule with the funiculus. There is no fusion
The micropyle is present at the bottom near the funiculus The micropyle is present at the apex
Anatropous ovule are very common in angiosperms Orthotropous ovule are less abundant

Q.6. Explain the structure of a mature pollen grain, along with a neat labelled diagram.

Sol: Structure of a mature pollen grain

Pollen grain

Pollen grains represent the male gametophyte. The detailed structure of a pollen grain is mentioned below:

  1. A pollen grain is surrounded by a prominent two-layered wall, called intine and exine.
  2. The exine is a hard, thick layer composed of sporopollenin, which functions by protecting the pollen grain against enzymes, alkali, strong acids and high temperature.
  3. Intine, a thin inner wall of the pollen grain is made up of cellulose and pectin.
  4. Germ pore, the prominent aperture is present in the exine layer of the pollen grain, which functions by the formation of the pollen tube and in releasing the male gametes during fertilisation.
  5. The cytoplasm of the pollen grain is surrounded by plasma membranes.
  6. Pollen grain consists of two cells, the vegetative cell and generative cell on maturity.
  7. The vegetative cell is larger in size and comprises a large irregularly shaped nucleus with a large amount of reserve food materials.
  8. The generative cell is smaller in size and floats inside the cytoplasm of the vegetative cell.
  9. Each pollen grain possesses two types of the nucleus called the generative nucleus and tube nucleus.
  10. The generative nucleus divides and forms two male gametes nucleus and develops a pollen tube after pollination.
  11. In some plant species, pollen grains externally possess sharp teeth like projection help in adhering of pollen grains to the stigmatic surface.
  12. In many cases, the pollen grains are shed at two-celled- vegetative cells and generative cells. Whereas in some, three celled stages- vegetative cell and two male gametes.

Q.7. Write the difference between Microsporophyll and Megasporophyll.

Sol:

Microsporophyll Megasporophyll
The sporophylls bear microsporangia. The sporophylls bear megasporangia.
Consists of numerous microspores or pollen grains. Consists of only one functional megaspore.
The spores are not retained as they are shed away. The spores are retained inside the megasporangium.
In angiosperms, the microsporophyll is modified into stamen. In angiosperm, the megasporophyll is rolled to produce a carpel.
The male gametophyte is formed near the female gametophyte. The female gametophyte is produced inside the megasporangium.
The spores produced by microsporophyll develop into the male gametophyte. The spores produced by megasporophyll develop into the female gametophyte.

Q.8. What is the male gametophyte? Explain the development of male gametophyte?

Sol: Male gametophytes are also called pollen grains. It is the first gametophytic structure to be formed with the modification of a microspore mother cell into the pollen grain.

Male gametophyte development can be classified into two stages: Pre-pollination development and post-pollination development.

Q.9. What is pollen sac? Draw a neat labelled diagram of a pollen sac.

Sol: The pouch-like structures present in seed plants where pollen is produced. These pollen sacs are present within the anther and are found both in angiosperms and gymnosperms and differ in their numbers. In angiosperms, there are around four to five pollen sacs and contain the micro spore mother cells. In gymnosperms, there are variable numbers of pollen sacs that are borne on the micro sporophylls, which make up the male cone.

Pollen sac

Pollen sac

Q.10. What is Ovule? Explain the different types of Ovules with a neat labelled diagram.

Sol: Ovule is the female reproductive structure of a flower, which is found inside the ovary of the pistil of a flower. These reproductive structures are involved in producing egg cells. After the fertilization process, the ovule swells, thickness its wall and develops into a seed. Based on their shapes, ovules are categorized into six different types:

  1. Orthotropous – Also called Atropous. The body of these ovules become completely straight during development.
  2. Anatropous – The body of these ovules become completely inverted during development.
  3. Hemi-anatropous- The body of these ovules changes to a right-angled position during development.
  4. Campylotropous-The body of these ovules is completely bent by losing the alignment between the chalaza.
  5. Amphitropous-The body of these ovules is very much curved, which takes the shape of a horseshoe during development.
  6. Circinotropous– In this case, the body of these ovules stretches long to create a full circle during development.

Types of Ovules

Types of Ovules

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