Oxygen moves from alveoli to the bloodstream ____
a. because the concentration of oxygen is greater in alveoli than in the blood
b. mainly due to the activity of carbonic anhydrase in the red blood cells
c. against a concentration gradient
d. to equal the concentration of CO2 in the blood
e. by active transport
ANSWER: a
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Before contact with Europeans, a tiny, isolated group of South Pacific islands had a population of about 50,000 people. Because of poor management of their own resources, the population fell to around 5000 by about the year 1750
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