What is pollination? How does it occur in plants? How does pollination lead to fertilization ? Explain.

Explanation

The transfer of pollen grains from anthers (male sexual parts) of a flower to the stigma part of the pistil (female sexual part) is known as pollination. Pollination is done by insects, birds, wind and water.
Pollination can occur in two ways:
(i) Self pollination. When the pollen grains from the anther of a flower are tansferred to the stigma of the same flower or another flower on the same plant, it is called self pollination.
(ii) Cross pollination. When the pollen grains from the anther of a flower on one plant are transferred to the stigma of a flower on another similar plant, it is called cross pollination.
When a pollen grain falls on the stigma of the carpel, it grows a pollen tube downwards through the style towards the female gamete in the ovary. A male gamete moves down the tube. When the pollen tube enters the ovule, its tip bursts open and male gamete comes out of the pollen tube and combines with the nucleus of the female gamete and forms zygote. This process is known as fertilization.