The annual flow of nitrogen through organic nitrogen could not have come from dung alone. Suggest another source of organic nitrogen.

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.

Which body region are part of the cephalic region?

Which of the following cognitive skills have not been displayed by animals? a. using tools b. forming concepts c. transmitting culture d. using syntax