Question

Lungs without air sacs occur in
A. Sparrow
B. Peacock
C. Penguin
D. Falcon

Answer 1

Hint:- The anatomy of the birds are somewhat different compared to all other animals, this is
mainly because of unique nature of birds that is flying, because of this all the organs and tissues are
arranged in such a way to adapt the flight mode.

Complete step-by-step solution:- Birds have unique features, and this is due to flying nature of birds and skeleton system is very
lightweight but the musculature is powerful, and at the same time it has powerful circulatory
and the respiratory system.
2. As birds have to flight, it has strong metabolism and need more oxygen, in order to meet the
oxygen demand the respiratory system has little changes.
3. Birds have lungs for the respiration, but it is not similar like lungs present in humans, because in
humans and other animals like amphibians, and reptiles, where lungs undergo both expansion
and contraction but here, the lungs are rigid, and it consists of air sacs.
4. The air sacs that present in the lungs of the birds act as the bellows that ventilate the lungs are
the air sacs.
5. Air sacs in birds are distributed throughout much of the birds#39; bodies.
6. In the air sacs air moves in a unidirectional way, through the parabronchi of the rigid lungs.
7. Even though bird lungs are smaller than those of mammals of when comparable size, those air
sacs account for 15% of the total body volume of birds.
8. whereas in mammals, the alveoli are present instead of air sacs and they act as the bellows
where they constitute only 7% of the total body volume.
9. As the walls of the air sacs do not have a good blood supply and so do not play a direct role in
gas exchange. Instead they help in direct entry of air.
10. From all above given every bird lungs have air sacs, except for Penguin as it is flightless bird.
So the correct option is C.

Note:- To say simply birds anatomy made it in very light weight but other systemic structures are made strong in order to meet the demands of oxygen say they have high metabolic activity, in a same way air sacs are present in lungs, but those air sacs are absent in some flightless birds.