Anna waters her plants with salty water to them grow better. is her thinking correct? a. no. the salt will interfere with absorption of water and the plants will die. b. no. the salt will cause the water to diffuse out of the plants and they will wilt. c. yes. salt will increase the water uptake of the plant. d. yes. salt will provide the plant with sodium and chloride ions.

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.