Question
Tue February 19, 2013 By: Disha Zanwar

Why is one germ cell large and contains the food stores while the other is smaller and likely to be motile?

Expert Reply
Wed February 20, 2013
The male gamete has to leave the male organism and reach the site of fusion in the female reproductive tract. For this purpose, it needs to swim actively for which it should be light, small and provided with a long tail. The sperm cells are active, using their tails to swim against the stream of fluid in the oviduct.
The female gamete need not leave the female body and hence lacks any structure for locomotion. The ovum is externally not active. After release, the ovum is passively moved by the fluid-flow in the oviduct. After fertilization, the ovum needs to support the growth and division of the zygote for some time and hence it has a large amount of cytoplasm containing stored nutrients for providing energy for this purpose.
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