In the context of pollen grains, the two main walls are denoted as A and B. Which option correctly matches A and B?

A - exine, B - intine

The pollen grains have two prominent walls: the exine and the intine. The exine is the outermost wall layer of the pollen grain, while the intine is the innermost layer.

The exine is composed of a tough and resistant material called sporopollenin, which helps protect the pollen grain from environmental stresses. It also gives the pollen grain its characteristic shape and structure.

The intine, on the other hand, is a thin and flexible layer located beneath the exine. It is mainly composed of cellulose and pectin and is responsible for the growth and development of the pollen tube after pollination.

Together, the exine and intine play important roles in the protection and reproductive function of pollen grains.