In which of the following organisms does blood flow from the lungs to the heart before circulating through the rest of the body?
A) annelids
B) mollusks
C) fishes
D) frogs
E) insects

Question

Quizplus · Accepted Answer

Frogs have a double-loop circulatory system where blood flows from the lungs to the heart, and then is pumped out to the rest of the body. This is different from the single-loop system seen in fishes, where blood flows from the gills to the body and then back to the heart without a separate trip through the lungs. Annelids, mollusks, and insects have different circulatory mechanisms that do not involve a lung-heart-body sequence as seen in frogs.

In Which of the Following Organisms Does Blood Flow from the Lungs