Class 12th Biology 2012 Set2 Delhi Board Paper Solution

(a) The middle piece possesses numerous mitochondria, which produces energy for the movement of tail that facilitate sperm motility essential for fertilisation.

 

(b) Microsporangium are surrounded by 4 wall layers, epidermis, endothecium, middle layer and tapetum. Outer 3 wall layers performs the function of protectionand help in dehiscence of anther to release the pollen. The innermost wall layer is the tapetum, it nourishes the developing pollen grains. Cells of the tapetum

possess dense cytoplasm and generally have more than one nucleus.

 

(c) Luteinizing hormone acts at the Leydig cells and stimulates the synthesis and secretion of androgens.