Question

Which of the following adaptation/s is required for flight in birds?
(i) Streamlined body
(ii) Forelimbs modified into wings
(iii) Ossified bones
(iv) Presence of air sacs

• A. Only (iv)
• B. (i), (ii) and (iii)
• C. Only (i) and (iv)
• D. (i), (ii) and (iv)

Answer 1

The correct option is D (i), (ii) and (iv)

The bodies of all flying birds are shaped like teardrops. The streamlining is achieved by specially arranged feathers that reduce the friction air resistance during flying.

A bird's forelimbs are modified as wings to assist in their flight.

Long bones in birds are hollow. They are filled with air and are called pneumatic bones. This helps in flight by reducing the body weight. Ossified bones are seen in humans or other animals which means they lack air pockets and are completely solid and hard.

The presence of air sacs in the lungs of birds serve as internal compartments which hold air. It facilitates internal air passage to allow birds to have a continuous flow of large volumes of air as a way to increase oxygen exchange capacity and efficiency so they can fly for very long distances without getting tired.