Answers

Saroj Kumar
Jul 29, 2020

The angiosperm pollen grains comprises of outer exine made up of resistant organic material sporopollenin, while inner thin layer of intine is made up of cellulose and  pectin.Since, the outer hard layer of exine is made up of sporopollenin which is one of the most resistant organic substance, it helps the pollen grains to resist high  temperatures, strong acids and alkali and it also protects them from enzyme degradation.