Question

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

Answer 1

Hint: In birds, it was seen that their forelimbs are modified to a specific structure which has many important functions in making the life of birds easy and increasing their chances of survival. Birds have hollow bones.

Complete solution: Forelimbs of birds are modified into the special structure known as the wings that help them to fly. These wings create a downward force that helps the birds to lift up. The bodies of birds are adapted for flying. Many of a bird’s bones are less dense than the bones of humans which makes bird’s bodies lightweight. Since the bird bones are hollow, this type of bones is known as pneumatic bones, which helps to reduce the weight of the birds. The feathers which are present in the birds are the most distinguishing feature of all birds. Feathers mostly have the modified scales that help the wings generate thrust and lift. Their body is streamlined which helps to reduce the drag as the bird travels through the air. The birds have keeled sternum bones that were used for the attachment of enormous muscles that power their wings, and a special bone called because of the semilunate carpal that permits them to flap their wings efficiently.

Additional Information: The long flight feathers on the wings and tail
help birds to make the balance while flying. Also, birds have a system of air sacs in their body that
hook up with the lungs. The air sacs enable birds to extract far more oxygen from each breath of air than
other animals can. Extra oxygen is required by the birds to release large amounts of energy to
power their flight. Birds get more oxygen because of their four-chambered heart. The advantage of a
a four-chambered heart is that there’s no mixing of oxygen-rich and oxygen-poor blood. Blood that arrives within the bird’s body tissues has much oxygen.

So, the correct answer is ‘All of the above’.

Note: Birds even have well-developed brains and keen eyesight. During flying, birds must have very quick reactions. When landing on a tree or cliff, a bird has only a few seconds to identify an area to land safely and avoid crashing. Most birds have keener eyesight than humans do.