Question

Single circulation blood flows through the heart only once during one cycle of passage through the body. This is exhibited by
A) Labeo, chameleon, salamander
B) Hippocampus, exocoetus, anabas
C) Hyla, rana, draco
D) Whale, dolphin, turtle

Answer 1

Hint:Belongs to Pisces (fish) and has two chambered hearts with one atrium and one ventricle. The exchange of gases takes place at gills.

Complete answer:
The circulatory system consists of network of blood vessels that supply the body, oxygen and nutrients and remove carbon dioxide and waste from the body. Heart is the central organ in circulatory system that pumps blood throughout the body. To exchange the gases the coordination between the circulatory and respiratory system (gills and lungs) is necessary. In invertebrates the two main circulation pathways are the single and double circulation pathways. Single circulatory system is found in fishes and consists of a blood, blood vessels and double chambered heart with an atrium and ventricle. The deoxygenated blood from the body is received in the atrium and pumps it through the ventricle to the gills where exchange of gases takes place so that blood gets deoxygenated; the process is called gill circulation.

The oxygenated blood then passes through the whole body and is received back in the atrium; this is called systemic circulation. Around the fish’s systemic circuit, gradient of oxygenated to deoxygenated blood is produced due to the unidirectional blood flow which results in reduced overall metabolic capacity of fish. Blood flow in amphibians, reptiles, birds, and mammals is directed in two circuits formed by pulmonary circulation and systemic circulation. In pulmonary circulation blood passes through the lungs and then back to the heart and in systemic circulation blood flows throughout the body and its organs including the brain. Although there is difference in structure of heart and circulation process in amphibians, reptiles, birds, and mammals but all have double circulation.

Thus, the correct answer is option B. i.e., Hippocampus, exocoetus, anabas

Note:Fishes possess a single circulation system with a simple two chambered heart consisting of one atrium and one ventricle. The blood gets oxygenated at gills and is supplied throughout the body.