Chapter 1: Sexual Reproduction in Flowering Plants Short Questions | biology Class 12 CBSE

ByteNotes

Chapter 1: Sexual Reproduction in Flowering Plants Short Questions | biology Class 12 CBSE | ByteNotes.in

Short Answer

Easy difficulty • Direct answer format

Easy

Question 1

Quick Recall

What is the role of the tapetum in anther development?

The tapetum is the innermost wall layer of the microsporangium and directly surrounds the sporogenous tissue.
It nourishes the developing pollen grains by supplying essential nutrients and enzymes.
Tapetal cells possess dense cytoplasm and generally have more than one nucleus, reflecting their high metabolic activity.

ByteNotes

Short Answer

Easy difficulty • Direct answer format

Easy

Question 2

Quick Recall

Define microsporogenesis. What is the ploidy of the cells formed at the end of this process?

Microsporogenesis is the process of formation of microspores (pollen grains) from the pollen mother cell (PMC) through meiotic division inside the microsporangium.
The microspores are arranged in a cluster of four cells called the microspore tetrad after meiosis.
The microspores are haploid (n) in ploidy since they are formed by meiosis from the diploid (2n) pollen mother cell.

ByteNotes

Short Answer

Medium difficulty • Direct answer format

Medium

Question 3

Quick Recall

Why is sporopollenin considered the most resistant organic material? What is its significance in palaeobotany?

Sporopollenin forms the exine (outer wall) of pollen grains and can withstand high temperatures, strong acids, and alkalis.
No enzyme capable of degrading sporopollenin is known, which makes it extraordinarily resistant to chemical and biological breakdown.
Because of its extreme resistance, pollen grains are well-preserved as fossils, making them invaluable as tools in palaeobotanical studies to reconstruct past vegetation.

ByteNotes

Short Answer

Medium difficulty • Direct answer format

Medium

Question 4

Quick Recall

Distinguish between the vegetative cell and the generative cell in a mature pollen grain.

The vegetative cell is larger and contains abundant food reserves along with a large, irregularly shaped nucleus; it forms the pollen tube upon germination.
The generative cell is smaller, spindle-shaped, with dense cytoplasm and a compact nucleus, and it floats in the cytoplasm of the vegetative cell.
The generative cell later divides mitotically to give rise to two male gametes, either before shedding (3-celled pollen) or during pollen tube growth (2-celled pollen).

ByteNotes

Short Answer

Medium difficulty • Direct answer format

Medium

Question 5

Quick Recall

What is the significance of germ pores in a pollen grain?

Germ pores are prominent apertures on the exine of pollen grains where the sporopollenin layer is absent.
They serve as the point of emergence of the pollen tube during pollen germination on the stigma.
The number and position of germ pores are characteristic features of pollen grains and are used in pollen identification.

ByteNotes

Short Answer

Medium difficulty • Direct answer format

Medium

Question 6

Quick Recall

What is megasporogenesis? How does it differ from microsporogenesis in terms of the cells involved?

Megasporogenesis is the process of formation of megaspores from the megaspore mother cell (MMC) through meiotic division inside the nucellus of the ovule.
In microsporogenesis, pollen mother cells (PMCs) in all four microsporangia of an anther divide to produce microspores; in megasporogenesis, usually a single MMC in the micropylar region of the nucellus divides.
Microsporogenesis produces four equally functional microspores (microspore tetrad), whereas megasporogenesis produces four megaspores of which only one is functional and the other three degenerate.

ByteNotes

Short Answer

Medium difficulty • Direct answer format

Medium

Question 7

Quick Recall

State the structure of a mature angiosperm embryo sac. Why is it described as 7-celled and 8-nucleate?

After the 8-nucleate stage, cell walls are laid down to form 7 cells: the egg apparatus (2 synergids + 1 egg cell) at the micropylar end, 3 antipodals at the chalazal end, and 1 large central cell.
The central cell contains two polar nuclei (not surrounded by individual cell walls as separate cells), making the total nuclei count eight even though there are only seven cells.
Hence, a mature embryo sac is described as 7-celled (having cell walls organised around 6 nuclei + 1 large central cell) but 8-nucleate (including the 2 polar nuclei in the central cell).

ByteNotes

Short Answer

Medium difficulty • Direct answer format

Medium

Question 8

Quick Recall

What is the function of the filiform apparatus in the embryo sac?

The filiform apparatus consists of special cellular thickenings at the micropylar tip of the synergids.
It plays an important role in guiding the pollen tube into the synergid during fertilisation.
Recent studies have confirmed that the filiform apparatus directs pollen tube entry into one of the synergids so that male gametes are discharged into the embryo sac.

ByteNotes

Short Answer

Easy difficulty • Direct answer format

Easy

Question 9

Quick Recall

What is autogamy? Name two structural features of flowers that promote autogamy.

Autogamy is the type of pollination in which pollen grains from the anther are transferred to the stigma of the same flower.
Synchrony in pollen release and stigma receptivity is one feature that promotes autogamy, ensuring both are available at the same time.
Close proximity of the anther and stigma within the same flower (as in cleistogamous flowers) is another feature that guarantees autogamy, preventing outside pollen from reaching the stigma.

ByteNotes

Short Answer

Easy difficulty • Direct answer format

Easy

Question 10

Quick Recall

Differentiate between geitonogamy and xenogamy.

Geitonogamy involves transfer of pollen grains from the anther to the stigma of another flower on the same plant, while xenogamy involves transfer from a flower of a completely different plant.
Genetically, geitonogamy is equivalent to autogamy since the pollen originates from the same plant; xenogamy brings genetically different pollen to the stigma and introduces new genetic combinations.
Both geitonogamy and xenogamy require a pollinating agent, but only xenogamy leads to genetic diversity in the offspring.

ByteNotes

Short Answer

Medium difficulty • Direct answer format

Medium

Question 11

Quick Recall

What is self-incompatibility? How does it prevent self-pollination?

Self-incompatibility is a genetic mechanism by which a plant prevents its own pollen (from the same flower or other flowers of the same plant) from fertilising the ovules.
It acts by inhibiting pollen germination on the stigma or by arresting pollen tube growth within the style, thereby blocking fertilisation.
The recognition between compatible or incompatible pollen and the pistil is mediated by chemical interactions between the pollen components and those of the pistil.

ByteNotes

Short Answer

Medium difficulty • Direct answer format

Medium

Question 12

Quick Recall

Why do wind-pollinated flowers not produce nectar or have colourful petals?

Wind-pollinated flowers rely on air currents rather than animals to transfer pollen, so there is no need to attract animal pollinators.
Nectar and bright colours serve as rewards and visual signals to attract biotic pollinators like insects and birds, which are irrelevant in wind pollination.
Producing nectar and colourful petals would be a waste of energy and resources for wind-pollinated plants, which instead invest in producing large quantities of lightweight, non-sticky pollen.

ByteNotes

Short Answer

Easy difficulty • Direct answer format

Easy

Question 13

Quick Recall

What is double fertilisation? Why is it unique to angiosperms?

Double fertilisation involves two separate fusion events: syngamy (fusion of one male gamete with the egg cell to form a diploid zygote) and triple fusion (fusion of the other male gamete with two polar nuclei to form the triploid PEN).
It is unique to angiosperms because no other group of plants undergoes two fusion events — a functional triple fusion forming endosperm — within the same embryo sac.
The products of double fertilisation are the diploid zygote (which becomes the embryo) and the triploid primary endosperm nucleus (which forms the nutritive endosperm tissue).

ByteNotes

Premium Access

Unlock all Short Questions

You are viewing 13 free short questions from this chapter. Upgrade to Premium to unlock the remaining 12 questions.

Upgrade to Premium12 questions locked

Chapter sections

Chapter 1: Sexual Reproduction in Flowering Plants | Short Questions

What is the role of the tapetum in anther development?

Define microsporogenesis. What is the ploidy of the cells formed at the end of this process?

Why is sporopollenin considered the most resistant organic material? What is its significance in palaeobotany?

Distinguish between the vegetative cell and the generative cell in a mature pollen grain.

What is the significance of germ pores in a pollen grain?

What is megasporogenesis? How does it differ from microsporogenesis in terms of the cells involved?

State the structure of a mature angiosperm embryo sac. Why is it described as 7-celled and 8-nucleate?

What is the function of the filiform apparatus in the embryo sac?

What is autogamy? Name two structural features of flowers that promote autogamy.

Differentiate between geitonogamy and xenogamy.

What is self-incompatibility? How does it prevent self-pollination?

Why do wind-pollinated flowers not produce nectar or have colourful petals?

What is double fertilisation? Why is it unique to angiosperms?

Unlock all Short Questions