The saccus of $Pinus$ pollen is a modification of:

Select the correct option in which the following terms are arranged in the correct developmental sequence:
$(A)$ Pollen grain
$(B)$ Pollen mother cell
$(C)$ Microspore tetrad
$(D)$ Male gametes
$(E)$ Sporogenous tissue

What is the group of compactly arranged homogeneous cells located at the center of each microsporangium in a young anther called?

In angiosperms,a male gametophyte is developed from a pollen mother cell by . . . . . . .

How many layers is the pollen grain wall composed of?

Approximate diameter of pollen grain is