A major evolutionary change between thefishcirculatory system and the circulatory systemsofamphibians, birds, and mammalians is the presence of a
A) separate pulmonary circuit in fish.
B) two-chambered heart in amphibians, birds, and mammals.
C) double-loop pathway in amphibians, birds, and mammals.
D) stronger atria in amphibians, birds, and mammals.
E) four-chambered heart in fish.

Question

Quizplus · Accepted Answer

The major evolutionary change is the development of a double-loop circulatory pathway in amphibians, birds, and mammals, which includes separate pulmonary and systemic circuits, unlike the single-loop system found in fish.

A Major Evolutionary Change Between Thefishcirculatory System and the Circulatory