Question

Which of the following characters represents flight adaptation of birds?
A. Bones are pneumatic.
B. Sternum has a keel for attachment of flight muscles.
C. Forelimbs are modified into wings.
D. All of the above.

Answer 1

Hint: The bodies of birds are adapted for flying. Their bones are less dense than human bones, which makes birds' bodies lightweight. Flying birds have huge and strong chest muscles that aid in moving the wings during flying.

 Complete answer: Birds have a strong, but a light-weight framework built of typically specialized bones. This is made possible by the fusion and also the elimination of some particular bones while the remaining are hollowed; these types of bones are known as pneumatic bones.
1. Some bones of the pelvis and vertebrae are fused together to aid this.
2. Pneumatic bones have air spaces within them which make them lighter than most solid bones. They're only found within the skull.
3. The breastbone, commonly known as the sternum is among the most important bones of a bird's skeleton and is a major component of the girdle which is crucial for the attachment of flight muscles.
4. Forelimbs of birds are specialized and hence modified into wings; a typical avian feature, that helps them to fly. All these are the various evolved features found in birds which helps them in flight.

So, the correct answer is option D. All of the above.

Note: The birds have a spindle-shaped body to supply less air resistance during flight. This helps the birds to conserve most of their energy and make use of the same efficiently while flying. The various morphological adaptations and anatomical adaptations combined together is what makes flight possible in birds.