NCERT Questions for Class 12 Biology Chapter 1 – Sexual Reproduction in Flowering Plants

Important Questions with Solutions of Class 12 Biology Chapter 1 – Sexual Reproduction in Flowering Plants

1) Distinguish between geitonogamy & xenogamy.

Ans – The differences between geitonogamy & xenogamy are:

Geitonogamy	Xenogamy
It is the process in which the pollen grains from the anther are transferred to the stigma of another flower of the same plant.	It is the process in which the pollen grains from the anther get transferred to the stigma of different plants.
It does not involve genetic recombination.	It involves gametic recombination.

2) Explain the arrangement in an embryo sac.

Ans – Being a 7-celled and 8-nucleated structure, an embryo sac is divided into three cells at the micropylar end & further divided into two synergids and one egg cell. Antipodals are the three cells by the chalazal end. The central cell contains two popular nuclei.

3) Cleistogamous flowers are always autogamous. Explain.

Ans – The process in which the cleistogamous flower does not open results in the pollen grains resting in the stigma of the same flower when the anther’s dehiscence in the bud makes it completely autogamous.

4) How does double fertilization refer to the fertilization method in flowering plants?

Ans – Fusion of the first male nuclei with the egg, producing a diploid zygote, and the second male nuclei with the Secondary nucleus, creating the primary endosperm nucleus, in flowering plants consequences in DOUBLE FERTILIZATION.

5) Define apomixis and state its importance.

Ans – Apomixis is an asexual reproduction resulting in the reproductive propagules without meiosis and syngamy. Offsprings are produced from the vegetative part of the plant body.

6) Distinguish between microsporogenesis and megasporogenesis.

Ans – The differences between microsporogenesis and megasporogenesis are:

Microsporogenesis	Megasporogenesis
Haploid microspores or pollen grains evolved from the diploid microspore mother cell.	The diploid megaspore mother cell produces megaspores.
In a tetrahedral tetrad, the pollen grains are arranged.	In a linear tetrad, the megaspores are arranged.
All the microspores have their functions intact.	Only one megaspore generates accurately.

7) Explain the process of pollination in salivia. State any four modifications required for such type of pollination.

Ans – The entomophily/pollination of insects in salivia mends the flower to cause a blip. The flower includes the upper (two petals) and the lower lip (three petals – the sitting pad for insects). While in regular conditions, the connective stays upright but during pollination, the corolla tube is penetrated by the insect directed towards the nectar sitting on the lower lip.

This automatically pushes the sterile anther lobe, bringing the fertile anther to the backside of the insects, blowing the fertile lobe. The back feathers and legs of insects are dusted with pollen grains.

Modifications required for such type of pollination are:

• The colors of the flowers are bright.
• The flowers pertain to nectar glands.
• The texture of the pollen grains is sticky and spiny.
• The flowers are large in size and stout.

8) Distinguish between wind-pollinated flowers & insect-pollinated flowers.

Ans – The differences between wind-pollinated flowers & insect-pollinated flowers are:

Wind-pollinated flower	Insect-pollinated flower
The flowers are small in size and have no color to it.	The flower color is bright.
The pollinated flowers neither have any odor nor any nectar.	The pollinated flowers pertain to nectar glands.
The pollen grains derived from here are dry & cannot get wet.	The pollen grains derived from here are adhesive in nature or spiny.
Stigma is large and well-exposed hairy and branched.	Stigma here is within the flower and is also small in size.

9) State the steps taken in creating microsporocytes into mature pollen grains.

Ans – In the early stage of development of the anther, the microsporangium forms the Sporogenous tissues by closely arranging the homogenous cells.

1. A pollen mother cell (PMC) is evolved by each cell of sporogenous tissue, forming microspore tetrad or pollen grains alongside.
2. A pollen or microspore mother cell (MMC) is formed as some get modified, losing their potential.
3. A group of four haploid cells is called microspore tetrad, while MMC undergoes meiosis.
4. The anther matured while the microspores dissociated from the tetrad and developed into pollen grains.
5. A double-layered wall (outer exine consists of sporopollenin) is formed as in the nucleus of microspores, the mitosis happens, producing bigger vegetative cells & smaller generative cells.

The pollen grains are released in two-celled stages, the inner intine consists of cellulose and pectin.

10) How is “Incompatibility the natural barrier in the fusion of gamete.”

Ans – Pollen-pistil incompatibility is the process in which both the plant species are incompatible thus pollen grains of a plant species cannot germinate on the stigma of other non-related species. These pollen grains grow on the stigma region of non-related species. However, egg fertilization doesn’t occur in the male gametes in angiosperm plants & this whole process is known as gametic incompatibility.

Ways to attain self-incompatibility are:

1. Pollen stigma interaction: The incompatibility does not allow the pollen grains to germinate on the stigma.
2. Pollen tube style interaction: Nevertheless, the inhibition of the incompatibility in pollen tube growth within stigma and style, pollen grains manage to germinate on the stigma, and pollen tube eventually penetrates the stigmatic surface.
3. Pollen-ovule interaction: With the inhibition of growth at the micropyle of the ovule, the pollen tube pierces and grows within the style.

Class 12 Biology Chapter 1 Sexual Reproduction in Flowering Plants Detailed Explanations

The method by which male and female gametes develop in plants and how they contribute to the creation of new plant kinds are explained by sexual reproduction in blooming plants. This section elaborates on the structure and processes of pre-fertilization, fusion of male and female gametes, pollination, and post-fertilization events. Biology Class 12 helps to learn the concepts in great detail and with a solid understanding.

The chapter includes information on all the components of a flowering plant, from development to eventual reproduction. Pollination is the process by which pollen grains are transferred to a pistil’s stigma. The chapter provides a thorough explanation of pollination as well as a clear illustration of the various forms, agents, and other aspects of pollination.

Important ideas of the chapter

The reproductive and genetically releasing systems for angiosperms or flowering plants have managed to make an intricate intertwining system. In essence, flowering plant reproduction is only simply characterized by pollination, fertilization, seed formation, and flower development. In effect, all of the above stages are interconnected if they are to be linked as part of plant reproduction processes.

Development of Flowers

The flowers are reproductive parts of the flowering plants. Their duty is to bring about pollens and attracting the pollinators which includes the birds, butterflies as well as bees. Main four structural parts of flower consists of sepals, petals, stamens along with carpels. By process, all the parts interrelated towards achieving fertilization and pollination.

Pollination and Fertilization

Seed Formation

After fertilization, an ovule will become a seed in which the embryo of the plant will be contained. It will be covered with a seed coat until its embryo may germinate into a new plant. The dispersal means is not the same for seeds-they may be dispersed either by wind, animals, or water to seek out favorable areas of colonization and to move along the reproductive cycle.

Plant reproduction determines survival and diversity in species. By reproducing, plants scatter their genetic material, and this means that they can adapt to new environmental changes. Again, plant reproduction keeps the environment in balance as it is used to provide food as well as other resources by other organisms.