What is the purpose of storing pollen grains in liquid nitrogen?

To extend their viability

The correct answer is Option (1)- To extend their viability.

Storing pollen grains in liquid nitrogen is done to preserve their viability for an extended period. Liquid nitrogen has an extremely low temperature of -196°C, which significantly slows down biological processes and effectively suspends the metabolic activities of the pollen grains. This preservation method is commonly used in pollen banks, similar to seed banks, to ensure the long-term storage and availability of diverse pollen resources for plant breeding and conservation programs.

It's important to note that storing pollen grains in liquid nitrogen does not induce mutations or enhance their fragrance. The primary purpose is to maintain their viability and genetic integrity, ensuring the availability of diverse pollen resources for future plant breeding activities.