Question

Which of the following is true of species of terrestrial snakes that often need to assume a vertical posture?

• A. They are more likely to be susceptible to circulatory failure in vertical postures than are sea snakes.
• B. Their hearts are less likely to be located at the midpoint of their bodies than is the case with sea snakes.
• C. They cannot counteract the pooling of blood in lower regions of their bodies as effectively as sea snakes can.
• D. The blood pressure at their midpoint decreases significantly when they are tilted with their heads up.
• E. They are unable to rely on muscle contractions to move venous blood from the lower torso to the head.

Answer 1

The correct option is A They are more likely to be susceptible to circulatory failure in vertical postures than are sea snakes.

The first sentence of the third paragraph says - "many terrestrial snakes in similar spatial orientations do not experience this kind of circulatory failure." This suggests that terrestial snakes assuming a vertical position do experience circulatory failure. Hence, A is the correct answer.

Terrestrial snakes have made several adaptations that enable them to deal with certain blood circulation demands. Thus, the rest of the answers are incorrect.