Question

Incomplete double circulation is observed in:

• A. Reptiles
• B. Birds
• C. Amphibians
• D. Both 1 and 3

Answer 1

The correct option is D

Both 1 and 3

The correct option is D.

Explanation of correct option:

1. Amphibians and reptiles have an incomplete double circulation.
2. Two atria and one ventricle make up its three-chambered heart.
3. When oxygenated and deoxygenated blood enters the left and right atriums, respectively, and mixes in the single ventricle, this is known as incomplete double circulation.

Explanation of incorrect option:

Option A:

1. Incomplete circulation is not only seen in reptiles, but also in amphibians.

Option B:

1. Warm-blooded organisms, such as mammals and birds, have a more efficient blood circulation system in the form of a four-chamber (similar to the heart in humans), in which oxygenated and deoxygenated blood are fully separated.
2. Birds and mammals both have complete double circulation. The left atrium receives oxygenated blood, while the right atrium receives deoxygenated blood in this scenario. The left ventricle pumps oxygenated blood out, while the right ventricle pumps deoxygenated blood out.

Option C:

1. Amphibians are not the only organisms having incomplete circulation, reptiles also have incomplete circulation.

Final answer: Amphibians and reptiles both have incomplete double circulation.