Which of the following are the only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart?
A)amphibians
B)birds
C)fishes
D)mammals
E)reptiles

Question

Quizplus · Accepted Answer

Fish are the only vertebrates in which blood flows directly from respiratory organs to body tissues without first returning to the heart. This is known as a single circulation system.

Which of the Following Are the Only Vertebrates in Which