The amniotic egg was a key adaptation allowing vertebrates to make the transition to life on land where diffusion to/from a watery environment could not allow a developing embryo to meet its metabolic needs. Its three membranes are the _____, which surrounds the embryo in a watery sac; the _____, which sequesters metabolic waste away from the developing embryo; and the _____, which surrounds the embryo and other sacs.

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Quizplus · Accepted Answer

The amniotic egg's three membranes are correctly identified in option D as the amnion, which surrounds the embryo in a watery sac; the allantois, which sequesters metabolic waste away from the developing embryo; and the chorion, which surrounds the embryo and other sacs.

The Amniotic Egg Was a Key Adaptation Allowing Vertebrates to Make