39. Which of the following organisms fix nitrogen in aquatic ecosystems?
(A) legumes
(B) chemoautotrophs
(C) cyanobacteria
(D) fungi
(E) phytoplankton

35. Life history strategies usually result from (A) environmental pressures. (B) natural selection. (C) conscious choice. (D) A and B only (E) A, B, and C

36. A recent study of ecological footprints (described in the text) concluded that (A) it is not possible for technological improvements to increase Earth's carrying capacity for humans. (B) current demand by industrialized countries is much smaller than the ecological footprint of those countries. (C) the ecological footprint of the United States is larger than the ecological capacity of its land. (D) Earth's carrying capacity would increase if per capita meat consumption increased. (E) Earth's carrying capacity for humans is about 10 billion.

37. Which of the following members of a marine food chain is most analogous to a grasshopper in a terrestrial food chain? (A) shark (B) zooplankton (C) phytoplankton (D) detritivore (E) fish

38. Which of the following statements about the biogeographical aspects of diversity is not correct? (A) Species richness on an island reaches an equilibrium point when immigration equals extinction. (B) Island equilibrium theory applies to the relatively short period of time when colonization is the important process determining species composition; over a longer time, actual speciation affects the composition. (C) A species may be limited to a particular range because it never dispersed beyond that range, or it dispersed but failed to survive in other locations. (D) The magnitude of photosynthesis is the factor that accounts for the major variations in species diversity over large areas of Earth. (E) The patterns of continental drift are important considerations in the study of the past and present distributions of species.

40. Which of the following statements is correct about biogeochemical cycling? (A) The phosphorus cycle is a sedimentary cycle that involves the weathering of rocks. (B) The carbon cycle has maintained a constant atmospheric concentration of CO2 for the past million years. (C) The carbon cycle is a localized cycle that primarily reflects the burning of fossil fuels. (D) The phosphorus cycle involves the rapid recycling of atmospheric phosphorus. (E) The nitrogen cycle involves movement of nitrogen very little of which is chemically altered by either the biotic or abiotic components of the ecosystem.

41. Which of the following strategies would most rapidly increase the genetic diversity of a population in an extinction vortex? (A) Introduce new individuals transported from other populations of the same species. (B) Sterilize the least fit individuals in the population. (C) Establish a reserve that protects the population's remaining habitat. (D) Control and reduce populations of the endangered population's predators and competitors. (E) Capture all remaining individuals in the population for captive breeding followed by reintroduction to the wild.

42. Which of the following would a landscape ecologist consider in designing a nature reserve? (A) patterns of landscape use by humans (B) possible edge effects related to human activities (C) human economic concerns (D) A and B only (E) A, B, and C

43. A person exposed to a new cold virus would not feel better for one to two weeks because (A) antigen receptors are not the same. (B) phagocytic cells must first be activated by the complement system. (C) it takes up to two weeks to stimulate immunologic memory cells. (D) specific B cells and T cells must be selected prior to a protective response. (E) V-J gene rearrangement must occur prior to a response.

44. Hormone X produces its effect in its target cells via the cAMP second messenger system. Which of the following will produce the greatest effect in the cell? (A) a molecule of hormone X injected into the cytoplasm of the cell (B) a molecule of activated, cAMP-dependent protein kinase injected into the cytoplasm of the cell (C) a molecule of cAMP injected into the cytoplasm of the cell (D) a molecule of hormone X applied to the extracellular fluid surrounding the cell (E) a molecule of cAMP applied to the extracellular fluid surrounding the cell

45. It is very difficult to sneak up to a grasshopper and catch it. Why? (A) They have binocular vision. (B) They have excellent hearing for detecting predators. (C) They have compound eyes with multiple ommatidia. (D) They have a camera-like eye with multiple fovea. (E) They have eyes with multiple fovea.