Agriculture can contribute to depletion of aquifers because A. we wash our produce before eating it B. pesticides can runoff into oceans - C. irrigation water often comes from groundwater D. animal waste runs off into surface waters

The finches on the galapagos island were similar in form except for variations of their beaks. darwin observed that these variations were useful for: attracting a mate defending territory building nests gathering food

Which of the following is not a possible effectof increasimg carbon dioxide levels in the atmosphere ?

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.