[Campbell Biology P.974] Which of the following statements about the evolutionary variations... | Practice Question
Which of the following statements about the evolutionary variations in double circulation is INCORRECT?
A: The heart of turtles, snakes, and lizards has a complete septum dividing the ventricle.
B: In alligators, arterial valves can temporarily shunt blood flow away from the lungs when the animal is underwater.
C: Birds and mammals, unlike amphibians and many reptiles, cannot vary blood flow to the lungs without varying blood flow throughout the body in parallel.
D: When a frog is underwater, its skin acts as the sole site of gas exchange due to shunting blood away from temporarily ineffective lungs.
Explanation
The text explicitly states that turtles, snakes, and lizards have an incomplete septum in their three-chambered heart, not a complete one. This allows for some mixing of blood, but also enables shunting of blood flow.