Question

Which of the following organisms have double circulation?

• A. Human
• B. Birds
• C. Crocodiles
• D. All of these

Answer 1

The correct option is (A):

Explanation of the correct option: ​

1. Double circulation occurs in mammals, reptiles, birds etc, in which the blood passes through the heart twice before completing a full circuit of the body.
   
2. Blood is pumped from the heart to the lungs and returns to the heart before being distributed to the other organs and tissues of the body.
   
3. The heart is divided into two separate compartments to prevent oxygenated blood returning from the lungs from mixing with deoxygenated blood from the other parts of the body.

Final Answer: Double circulation is observed in all of these.