Ubisch bodies are secreted by

Which one of the following is resistant to enzyme action?

Male gametophyte in angiosperms produces

Examine the figure given below and select the right option giving all the four parts $a, b, c$ and $d.$ Correctly identify

$a\quad \;b\quad\;c\quad\;d$

Generally in the wall of the anther lobes how many middle layers are formed

How many meiotic divisions are necessary to produce $100$ pollen grains