Why pollen grains are preserved as fossils?

Due to the presence of sporopollenin.

The correct answer is Option (3) – Due to the presence of sporopollenin.

Pollen grains are preserved as fossils primarily due to the presence of a durable and resistant substance called sporopollenin.

Sporopollenin is considered the hardest substance in the plant kingdom. It is a highly durable and resistant material that makes up the outer layer of pollen grains and spores.

Sporopollenin is known for its exceptional stability and resistance to various environmental conditions. It can withstand strong acids, high temperatures, enzymes, and other degrading agents, making it highly durable and long-lasting.

Due to its robust nature, sporopollenin helps protect the genetic material inside pollen grains and spores during dispersal and ensures their successful reproduction. Pollen grain exine has prominent apertures called germ pores where sporopollenin is absent. Pollen grains are well- preserved as fossils because of the presence of sporopollenin. The exine exhibits a fascinating array of patterns and designs. The inner wall of the pollen grain is called the intine. It is a thin and continuous layer made up of cellulose and pectin.