Question

Explain the structure of germinating pollen grain with the help of a labelled diagram.

Answer 1

Structure of the pollen grain: After pollination pollen grains are deposited on the stigma of the carpel. Under suitable conditions pollen grains produce a tube known as pollen tube. This tube grows down through the stigma and style towards the ovary.

The nucleus of the pollen grains divides by mitosis and forms two male gametes. The tip of the pollen tube after entering ovary discharges the two male gametes into the embryo sac.

One of the male gametes fuses with the egg to form the zygote. This fusion is called fertilization. Another male gamete fuses with the diploid secondary nucleus and forms the endosperm, a food storing tissue.