We are blood vessels that send blood back towards your heart. most of the blood we carry doesn't have much oxygen left in it. what is this?

Building glycogen from glucose molecules is an example of what

Cells destroy body cells infected by a virus or bacteria.

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.