Question

Double circulation is not found in

• A. Frog
• B. Fish
• C. Bird
• D. Human

Hint:

Remember the progression of the heart: Fish (2 chambers, single loop), Amphibians/Reptiles (3 chambers, incomplete double loop), Birds/Mammals (4 chambers, complete double loop).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Circulatory systems can be single or double.
\[\begin{array}{rl} \bullet & \text{Single Circulation: Blood passes through the heart only once in one complete circuit of the body. } \\ \bullet & \text{Double Circulation: Blood passes through the heart twice in one complete circuit. There are two pathways: pulmonary circulation (to the lungs) and systemic circulation (to the rest of the body). } \\ \end{array}\]

Step 2: Detailed Explanation:
\[\begin{array}{rl} \bullet & \text{Fish: Have a two-chambered heart (one atrium, one ventricle) and exhibit single circulation. The heart pumps deoxygenated blood to the gills for oxygenation, and this oxygenated blood then travels to the rest of the body before returning to the heart. } \\ \bullet & \text{Frog (Amphibians): Have a three-chambered heart (two atria, one ventricle) and show incomplete double circulation. Oxygenated and deoxygenated blood mix partially in the single ventricle. } \\ \bullet & \text{Bird and Human (Mammals): Have a four-chambered heart (two atria, two ventricles) and exhibit complete double circulation, which efficiently separates oxygenated and deoxygenated blood. } \\ \end{array}\] The question asks where double circulation is not found. This is true for fish.

Step 3: Final Answer:
Double circulation is not found in fish.