Question

Which describes a difference between birds and mammals?

A. Birds protect and feed their young.
B. Birds have nearly hollow bones.
C. Birds undergo internal fertilization.
D. Birds efficiently transport oxygen to cells.

Answer 1

One difference between birds and mammals is that birds have nearly hollow bones and a unidirectional system for breathing, providing efficient oxygen transport necessary for flight.

Step-by-step explanation:

The difference between birds and mammals lies in their respective respiratory systems and skeletal structures. Birds have nearly hollow bones that are filled with air and they possess a unique respiratory system. While both birds and mammals have lungs for gas exchange, birds breathe through a unidirectional system, where air flows consistently and only in one direction through their lungs, unlike the bidirectional system in mammals. This adaptation provides birds with a more efficient means of oxygen transport to cells, essential for their high-energy demands of flight.