Describe three human activities that threaten aquatic habitats?

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.

How is anaerobic respiration affected by changes in temperature? (5 points)based on the conditions of early earth, what conclusion can you draw about the amount of anaerobic respiration that was occurring at earth’s beginning? explain your answer.(5 points)if there was a sudden drop in temperature after the evolution of the first living cells, predict how that might have affected the changes in the atmosphere and the evolution of cyanobacteria and other autotrophs. explain your answer. (5 points)

Through wich tissue do sugar get transported to reach the leaves during growth and reproduction