Generally only one sperm fertilizes an egg because
A) sperm compete against one another before entering and only the most fit sperm is able to fertilize the egg.
B) sperm travel such a great distance that no two sperm are likely to arrive at the same time.
C) there is only one passageway available for a sperm to enter the egg.
D) many sperm enter but only one set of chromosomes can fuse with the egg nucleus; the other sperm are absorbed.
E) when the first sperm fuses with the egg membrane, the membrane depolarizes, which blocks the entry of any other sperm.

Question

Quizplus · Accepted Answer

When the first sperm fuses with the egg membrane, the membrane depolarizes, which blocks the entry of any other sperm. This is known as the fast block to polyspermy. After this, the egg goes through a slower block to polyspermy, which involves changes in the egg membrane that prevent additional sperm from entering. Therefore, only one sperm is able to fertilize the egg.

Generally Only One Sperm Fertilizes an Egg Because