Answer:D
Explanation: The pulmonary air sacs of birds only permit a unidirectional flow of air through the lungs. Unidirectional flow means that air is inhale and exhale through one trachea alternatively. This means the bird lungs only receive largely fresh air which has a high oxygen content during inhalation and do not receive fresh during exhalation. While air flow bidirectional in mammals.
Its B.
becuase the radiation forms the ultra violet radiation and absobs it.
A toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.
Answer:
the differnt dna and rna strucures in the mammals cause differen tlooks they have also evolved from being in the wilf most of their lives
Explanation:
Answer:
B: A whole set
Explanation:
The only cells in your body that don't are sex cells. ie. Eggs and Sperm
