Question

Air sacs of birds are helpful

• A. To lessen the body weight
• B. To keep the body warm
• C. To regulate the body temperature
• D. In blood circulation

Answer 1

Answer: (A)

To lessen the body weight

The birds have a number of thin-walled air sacs that can extend to approximately 10 times the volume of the lungs. They are present within body cavities and extend into some specific bones to take the place of the bone marrow. This has the added function of reducing the weight of the bone, as they are essentially filled with air. Hence, option A is correct.