The cytoplasm of a neuron contains many negatively charged proteins, which give the cell a slightly negative charge at rest. what do you think happens to this charge when the neuron is stimulated?

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.