Question

What purpose does the tail in a sperm serve?

Answer 1

A sperm's tail is whip like i.e. very long and slender. This structure helps to propel the sperm forward in a snake like motion through the energy produced by the 'midpiece'. Otherwise all of the sperms would move laterally or in repetitive circles, thus making it impossible for any of them to enter the egg, hence a baby being born.

Answer 2

The tail gives the sperm cell movement.