Water supply shortages will affect many people by the middle of this century. the process of desalination, removing the from seawater, is one way to provide potable water. a) seed weed b) contaminants c) salt and minerals d) bacteria and algae identify the fuel that could be classified as a nonrenewable or renewable resource. a) biomass b) geothermal c) wind d) tidal

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.