Question

Which best explains the circulation system within mammals?

A. Mammals use a closed, double-loop circulatory system aided by a four-chambered heart.
B. Mammals use a closed, single-loop circulatory system aided by a four-chambered heart.
C. Mammals use an open, double-loop circulatory system aided by a four-chambered heart.
D. Mammals use a closed, single-loop circulatory system aided by a three-chambered heart.

Answer 1

A. Mammals use a closed, double-loop circulatory system aided by a four-chambered hearts.

The four chambered heart of a mammal is divided into two atria and two ventricles. Double-loop circulatory system is used. One loop for oxygenated blood, the other loop for deoxygenated blood.