Outer wall of pollen grain is made up of

Step-by-step solution

A pollen grain contains two layered cell wall, the outer exine and inner intine. Sporopollenin is found in the exine of pollen grains, which is the most resistant biological material known, of microbial and chemical decomposition. Due to this, pollen grains are well preserved during fossilization. Intine of pollen grain is made up of pectocellulose.