In sea urchins, the "fast block" and the longer lasting "slow block" to polyspermy, respectively, are ________.
A) the acrosomal reaction and the formation of egg white
B) the cortical reaction and the formation of yolk protein
C) the jelly coat of the egg and the vitelline membrane
D) membrane depolarisation and the cortical reaction

Question

Quizplus · Accepted Answer

The "fast block" to polyspermy in sea urchins involves membrane depolarization, which occurs within seconds of sperm contact with the egg. This is then followed by the "slow block" to polyspermy, the cortical reaction, which involves the release of calcium ions from the egg's cortical granules to form a fertilization envelope that physically blocks additional sperm from penetrating the egg.

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