If cells are placed in a hypertonic solution containing a solute to which the membrane is impermeable, what could happen? a. the cells will lose water and shrink. b. the cells will shrink at first, but will later reach equilibrium with the surrounding solution and return to their original condition. c. the cells will show no change due to diffusion of both solute and solvent. d. the cells will swell and ultimately burst.

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.