Where is sporopollenin found?

The innermost wall layer of the anther is the tapetum. What is the primary function of the tapetum?

The intine of pollen grains is composed of

What happens before the dehiscence of anther?

What does '$X$' represent in the given figure?

$P -$ This cell is big,has abundant food reserve and a large irregularly shaped nucleus.
$Q -$ This cell is small and floats in the cytoplasm of the vegetative cell. It is a spindle-shaped cell with dense cytoplasm and a nucleus.
$\quad\quad \quad P \quad \quad Q$