Question

Explain the events after pollination leading to the formation of a seed in angiosperms.

Answer 1

Pollination is the process of transfer of pollen grains from the anther to stigma
i. When the pollen grains fall on the stigma, the pollen tube enters one of the synergids and releases two male gametes.
ii. One of the male gametes moves towards the egg cell and fuses with it to form a zygote.
iii. The other male gamete fuses with the two polar nuclei and forms the primary endosperm nucleus. This is termed as triple fusion.
iv. After the triple fusion, the central cell becomes the primary endosperm cell (PEC). The primary endosperm nucleus gives rise to endosperm, while the zygote develops into an embryo.
v. Seeds are the fertilized ovules that are developed inside a fruit.
vi. The integuments of ovules harden to form the seed coat, and the micropyle facilitates the entry of oxygen and water into the seed.