Your teacher takes a candle and cuts some wax from the bottom of it. She puts the bit of wax in a beaker and places it on a hot plate. Eventually, the wax melts and becomes liquid. Do you think this is a physical or chemical change?

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.