Question

What are the events that occurs during gamete transfer in plants?

Answer 1

In flowering plants , pollen grains carry male gametes. When anther bursts, a large number of pollen grains are released. These pollen grains with the help of an agent (e.g., wind, water, insects) are transferred to the stigma of the pistil.

The transfer of pollen grains from anther to the stigma is called pollination. On reaching the stigma, pollen grain germinates and a tube-like structure called pollen tube comes out of it. Pollen tube carries male gametes and grows downwards through the style until it reaches to ovule situated in the ovary. On reaching the ovule, pollen tube enters into it and then releases male gametes near the egg.

In most of the terrestrial organisms, e.g., fungi, higher animals and majority of plants such as bryophytes, pteridophytes, gymnosperms and angiosperms, the process of fertilisation takes place inside the body of the organism. This type of gametic fusion is called internal fertilisation.

In all flowering plants, the zygote is formed inside the ovule. In most of the plants, with the formation of zygote, all the parts of the flower except the pistil wither and fall off. In some plants, such as tomato and brinjal, the sepals are persistent and remain attached to the developing fruit. In ovule, the zygote divides several times to form an embryo.

Meanwhile the wall of the ovule becomes hard and it develops into seed. With these developments, the wall of the ovary also starts to swell. As a result, the ovary develops into fruit. A thick wall that covers fruit is called pericarp. It is protective in function. When seeds mature, they are dispersed. Under favourable conditions, these seeds germinate to produce new plants.




Hope it helps!