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

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.

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.

46. Which of the following is the best explanation for the inability of an animal cell to reduce the concentration in its cytosol compared with the extracellular fluid? (A) low oxygen concentration around the cell (B) loss of transcription factors (C) low levels of protein kinase in the cell (D) blockage of the synaptic signal (E) insufficient ATP levels in the cytoplasm

47. All of the following represent adaptations by terrestrial animals to drying conditions except (A) salt glands. (B) increased thirst. (C) efficient kidneys. (D) anhydrobiosis. (E) impervious surfaces.

Use the data in Table.I to answer question 48.The data were obtained from a study of the length of tirne spent in each phase of the cell cycle by cells of three eukaryotic organisms designated beta, delta, and gamma. 48. The best conclusion concerning delta is that the cells (A) contain only one chromosome that is very short. (B) contain no DNA. (C) contain no RNA. (D) divide in the G₁ phase. (E) are actually in the G0 phase.

49. Which of the following is a characteristic of the early stages of local inflammation? (A) attack by cytotoxic T cells (B) release of histamine (C) fever (D) antibody- and complement-mediated lysis of microbes (E) arteriole constriction

50. Which of the following is not a component of an insect's defense against infection? (A) phenoloxidase activation, leading to the formation of large deposits around parasites (B) production of antimicrobial peptides (C) activation of natural killer cells (D) a protective exoskeleton (E) phagocytosis by hemocytes