Biologists are not sure about how many prodaryotic species on earth might be present. The problem is that

Biologists are not sure about how many prokaryotic species there might be. The problem is that

Assertion : estimate given by IUCN for biodiversity do not give any figures for prokaryotes. Reason : Biologists are not sure about how many prokaryotic species there might be.

Assertion (A): Biologists are not sure about total number of prokaryotic species. Reason (R) : Nearly 45,000 species of plants and twice as many of animals have been recorded from India.

How many species on Earth might still be waiting to be discovered and named?

Earth has originated about how many years ago ?