In sea urchins,the "fast block" and the longer-lasting "slow block" to polyspermy,respectively,are
A)the acrosomal reaction and the formation of jelly coat.
B)the cortical reaction and the formation of cortical granules.
C)the jelly coat of the egg and the vitelline layer.
D)membrane depolarization and the cortical reaction.
E)inactivation of the sperm acrosome.

Question

Quizplus · Accepted Answer

The "fast block" to polyspermy in sea urchins involves a membrane depolarization that occurs very rapidly (within seconds) upon sperm entry, preventing any additional sperm from attaching to the egg. The "slow block" involves the cortical reaction, which occurs several seconds after fertilization and involves the fusion of cortical granules with the plasma membrane, forming a fertilization envelope that physically blocks additional sperm from entering the egg.

In Sea Urchins,the "Fast Block" and the Longer-Lasting "Slow Block