Plant Reproduction

This question asks about the sequence of events after pollination — specifically the steps leading to fertilisation in a flowering plant.

After landing on the stigma, the pollen grain germinates, then a pollen tube grows down through the style toward the ovary. The male nucleus travels down this tube and enters the ovule through the micropyle.

Fertilisation — the fusion of the male nucleus with the egg cell — occurs inside the ovule, not in the style or on the stigma surface.

The correct sequence is: pollen germinates → pollen tube grows through style → male nucleus fuses with egg cell in ovule. This matches the choice “Pollen germinates → pollen tube grows through style → male nucleus fuses with egg cell in ovule” precisely.

The question tests knowledge of the sequential steps from pollination to fertilisation, including where the pollen tube grows and where fusion of gametes occurs.

The choice “Pollen germinates → male nucleus is released immediately → egg cell travels to pollen” states the male nucleus is released immediately and the egg cell travels to the pollen. This is incorrect — the egg cell stays in the ovule; the pollen tube grows toward the egg cell.

The choice “Pollen tube grows through the ovary wall → pollen germinates → nuclei fuse in the style” says the pollen tube grows through the ovary wall before the pollen germinates. The tube cannot grow before germination, and it grows through the style, not through the ovary wall.

The choice “Pollen dissolves into the stigma → male gamete diffuses to ovule → fertilisation occurs” describes pollen dissolving into the stigma and the gamete diffusing to the ovule. Pollen does not dissolve — it germinates and forms a pollen tube.

The choice “Pollen germinates → pollen tube grows through style → male nucleus fuses with egg cell in ovule” correctly states: pollen germinates → pollen tube grows through style → male nucleus fuses with egg cell in ovule. This is the accurate sequence.

The flower has large, brightly coloured petals, produces nectar, and has sticky pollen. These are the key distinguishing features of a particular pollination strategy.

Insect-pollinated flowers have large, colourful petals to attract pollinators visually, nectar to reward them, and sticky pollen that adheres to the insect's body as it feeds.

Wind-pollinated flowers have the opposite features: small or absent petals, no nectar, and smooth, lightweight pollen produced in large quantities to be carried by air currents.

All three features (large coloured petals, nectar, sticky pollen) are classic adaptations for insect pollination.

The question tests whether students can match flower features to the correct pollination vector based on known adaptations.

Wind-pollinated flowers do not need to attract anything — they have small or absent petals, no nectar, and produce vast quantities of smooth, light pollen. Sticky pollen and nectar are not useful for wind pollination.

Water-dispersed pollination involves pollen floating on water surfaces. Brightly coloured petals and nectar would offer no advantage in water pollination.

Explosive dispersal is a method of seed dispersal, not pollination. It is not a pollination vector at all.

Only insects as pollinators explains all three features: colourful petals attract them visually, nectar rewards them, and sticky pollen attaches to their bodies.