Question

(a) Name the organic material of the exine of the pollen grain. How is this material advantageous to pollen grain?
(b) Still, it is observed that it does not form a continuous layer around the pollen grain. Give reason.
(c) How are 'pollen banks' useful?

Answer 1

a) The exine of the pollen grain is made up of a resistant substance called sporopollenin. It helps the pollen grains to resist high temperatures and action of strong acids and alkalis. Since it cannot be easily degraded by enzymes, it can be preserved as fossils.

b) Sporopollenin is not continuous. At places and in regions where it is absent, it forms germ pores from where pollen tube formation takes place when pollen grain germinates on stigma.

c) Pollen banks are used to store pollen grains under viable conditions for longer periods of time so that they can be used later on for crop breeding programmes or in other biochemical or physiochemical studies.