In pollen banks pollen grains are stored in________at `-196^@C`.

In over 60 percent of angiosperms, pollen grains are shed at

The inner wall of pollen grain is called

The winged pollen are found in

Pollen grain is related to embryo sac as

In most of the water pollinated species pollen grains are protected from wetting by a

Explain giving two reasons why pollen grains can be preserved as fossils.

In plants that shed pollen grain at two-celled condition, the generative cell divides and form the two male gametes during the