Red blood cells have and generate energy
a. mitochondria; anaerobically
b. no mitochondria; anaerobically
c. mitochondria; aerobically
d. no mitochondria; aerobically
e. none of the above

What happens during interphase? (1)the nucleus grows to its full size. (2)the cell grows to its full size. (3)the nucleus divides into two nuclei. (4)the cell divides into two cells.

The “ecological footprint” left by a citizen of a developed nation is about four times larger than that left by a citizen of a developing nation. why is this the case?

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.