17. Acid Rain has an effect on natural systems (lakes, forests, etc) when the pH of the (rain or snow) is
A. less than 8 on the pH scale B. greater than 8 on the pH scale C. less than 7 on the pH scale
D. less than 5.6 on the pH scale E. greater than 9 on the pH scale
18. Natural selection will ultimately lead to a species that is:
A. more intelligent. B. physically bigger. C. adapted to its environment.
D. more aggressive. E. less vulnerable to its predators.
19. Carbon sequestration refers to what?
A. uncut tropical rain forests holding vast amounts of carbon in their vegetation
B. humans attempting to capture carbon from the burning of fossil fuels and storing that carbon underground
C. the oceans holding carbon and keeping it out of the atmosphere
D. all of the above may be considered carbon sequestration
E. only a and b
20. A bluebird and a tree swallow are living in the same territory and are using some of the same resources (feeding on flying insects). These two birds would be members of the same trophic level. A. True. B. False.