NEET BIOLOGY

Detailed explanation-1: -A substance called sporopollenin helps them in being well-preserved. Pollen grains have a two-layered wall out of which the exine in the outer hard layer is formed of sporopollenin. Sporopollenin is one of the most resistant organic materials. It can tolerate extremely high temperatures and strong alkali and acids.

Detailed explanation-2: -So, the correct answer is ‘sporopollenin’

Detailed explanation-3: -Sporopollenin is one of the most resistant organic compounds known. It protects pollen grains from external factors such as temperature, acid, alkali, etc. as sporopollenin is the component of the exine of plant spores.

Detailed explanation-4: -Because of the presence of sporopollenin, pollen grains are highly preserved as fossils.

Detailed explanation-5: -Sporopollenin is one of the most chemically inert biological polymers. It is a major component of the tough outer (exine) walls of plant spores and pollen grains. It is chemically very stable and is usually well preserved in soils and sediments.