Avaccine works to protect a mammal from a specific virus by having the mammal's body produce antibodies. the actual vaccine contains. a. viral proteins. b. viral antibodies c. strong forms of the virus. d. weakened forms of the virus.

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.