Question

Which one of the following animals has two separate circulatory pathways?
(A) Shark
(B) Frog
(C) Lizard
(D) Whale

Answer 1

Hint: In the double circulation system, the blood runs through the heart twice. It includes the pulmonary circulation and the systemic circulation. Since the blood flows twice through the heart, the blood can be transported to all the body surface at the higher pressure.

Complete Answer:
- In the double circulation system, the pulmonary circulation system takes place between the heart and the lungs and the systemic circulation takes place between the heart and the other parts of the body.
- This type of circulation is mainly seen in the mammals and the birds. In mammals, the artery carries oxygenated blood and the veins carry the deoxygenated blood in case of the systemic circulation.
- The pulmonary circulation is completely opposite to that of the pulmonary circulation. Whales belong to the mammal category, and hence it possesses the double circulation system.
- In the case of the single loop circulation system, the blood flows through the heart only once. And there is only one atrium and ventricle unlike the left and right arteries and ventricles in the double circulation system. In the given options except whale, all the other organisms follow the single loop circulation system.

Thus the option (D) is correct.

Note: In the double circulation system, the oxygenated blood carried from the lungs, the pulmonary veins discharge it into the heart and the heart pumps the blood that was carried by the systemic artery to all the parts of the body. And the deoxygenated blood carried by the systemic veins from all the parts to heart. And from there the pulmonary artery carries it to the lungs.