[Campbell Biology P.1093] If the release of contents from the cortical granules in a sea urch... | Practice Question

If the release of contents from the cortical granules in a sea urchin egg were inhibited, which of the following would be the most likely consequence?

  • A: The sperm would fail to bind to the egg jelly coat.
  • B: The acrosomal reaction would not occur.
  • C: The fast block to polyspermy would be unaffected, but the slow block would fail, leading to polyspermy.
  • D: The egg membrane would fail to depolarize, preventing the fast block to polyspermy.

Explanation

The text explains that the cortical reaction involves the fusion of cortical granules with the plasma membrane, which clips off sperm-binding receptors and causes the fertilization envelope to form, acting as a slow block to polyspermy Figure 47.2, point 4 . If this process is inhibited, the slow block fails, leading to polyspermy. The fast block membrane depolarization occurs earlier and is not directly dependent on cortical granule release.