Question

Pollen grains are shed at

• A. 1- celled stage
• B. 1-3- celled stage
• C. 4- celled stage
• D. 5- celled stage

Answer 1

Answer: (B)

1-3- celled stage

Pollen grain protoplast in uninucleate (1-celled) in the beginning but at the time of liberation, it becomes 2-3 celled. Actually, pollen grain nucleus grows in size and shifts to one side near the wall. The protoplast then divides to form two unequal cells generative cells (small) and tube or vegetative cell (large).
In some species, the generative cell divides into two male gametes prior to the dehiscence of anther and release of the pollen grains. Thus, at the time of pollination, pollen grain is either 2-celled (tube cell + generative cell) or 3-celled (tube cell + two male gametes). Pollen grains have not been noted so far in the 4-celled and 5-celled stage.

So, the correct answer is option B.