In angiosperms,two non-motile male gametes are produced by the division of the:

In plants,meiosis occurs in

Select the incorrect statement regarding microsporogenesis in an anther.

Pollen grains are generally spherical,measuring about

Where are the microsporangia located?

Which is an incorrect statement?
$I$. Each cell of sporogenous tissue in anther is capable of giving rise to a microspore tetrad.
$II$. The pollen grain represents the male gametophyte.
$III$. Pollen grains are usually triangular and $10-15 \mu m$ in diameter.
$IV$. Sporopollenin is one of the most resistant organic materials,which can be destroyed only by strong acids and alkalis.