In sea urchins, which of the following pairs of events most directly results in the short-lasting "fast block" and the longer-lasting "slow block" to polyspermy, respectively?
A) the acrosomal reaction and vitellogenesis
B) the cortical reaction and the formation of yolk protein
C) formation of the jelly coat and the vitellin membranes
D) membrane depolarization and the cortical reaction

Question

Quizplus · Accepted Answer

The "fast block" to polyspermy in sea urchins is achieved through membrane depolarization, which occurs immediately after the sperm binds to the egg, preventing additional sperm from fusing. The "slow block" is established by the cortical reaction, where cortical granules release their contents to form a fertilization envelope, physically blocking further sperm entry.

In Sea Urchins, Which of the Following Pairs of Events