An organic substance that can withstand environmental extremes and cannot be degraded by any enzyme is

Given below are two statements.
Statement $I$: Generally,anthers in angiosperms are dithecous,having two pollen sacs in each lobe.
Statement $II$: Each sporangium produces pollens from sporogenous tissues by the process of sporogenesis.
In light of the above statements,select the correct answer from the options given below.

Pollen grains are able to withstand extreme temperatures and strong acids and alkali because their exine is made up of:

The type of fossil pollen grains present in the area may be helpful in the exploration of

Because of which substance are pollen grains well preserved as fossils?

In angiosperms,male gametes are formed from