Birds have air sacs and lungs. When birds breathe (in / out,) oxygen-rich air fills the
lungs and air sacs. When birds breathe
(in / out), the oxygen-poor air leaves the
lungs, and stored fresh air enters the lungs from
the air sacs. This means that birds always have a
supply of oxygen-(rich / poor) air.

Explain the difference between incomplete dominance and codominance

Amino acids contain the elements carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. of the 20 amino acids found in humans, 11 are called "nonessential" because they can be manufactured by the body when needed. which elements in these 11 amino acids are commonly obtained from the metabolism of sugar molecules?

What best describes emerging scientific ideas