question_answer

What is the ratio of equational divisions that takes place in Cycas and angiosperms respectively during the formation of male gametes from pollen grains?

A)  3 : 2                                      

B)  3 : 1

C)  2 : 1                                      

D)  2 : 3

Correct Answer: C

Solution :

                 During gametogenesis in angiosperms the pollen-nucleus divides mitotically to form a generative cell and vegetative cell. The generative cell undergoes another mitosis to form two male gamete. In Cycas the microspore nucleus divides mitotically to produce small prothalial cell and large antheridial cell. The antheridial cell again divides to form generative cell and tube cell. The generative cell (after pollination) divides to form stalk cell and body cell. Just before fertilization    the    body   cell    enlarge blepharoplasts appear one at each pole and now the body cell divides into two antherozoids