44. Vaccinations are effective in combating future infections because they induce the production of
(A) helper T cells.
(B) neutrophils.
(C) prostaglandins.
(D) mutations in the host genome.
(E) memory cells.

40. What cell is haploid? (A) oogonium (B) zygote (C) primary oocyte (D) ovum (E) spermatogonium

41. Which of the choices lists the three phases of the ovarian cycle in the correct order? (A) follicular, luteal, ovulation (B) follicular, proliferative, secretory (C) luteal, ovulation, secretory (D) follicular, ovulation, luteal (E) luteal, secretory, ovulation

42. Which event of fertilization occurs first? (A) fast block to polyspermy (B) the entry of sperm DNA into the egg (C) the slow block to polyspermy (D) the acrosomal reaction (E) the cortical reaction

43. Which of the following is TRUE of a morphogen? It is a signaling molecule that (A) is required for cell-to-cell contact within the embryo. (B) induces the differentiation of cells within the embryo. (C) induces blastulation of the developing embryo. (D) induces implantation of the embryo into the uterus of mammals. (E) that separates out cytoplasmic factors to their respective cells within the developing embryo.

45. All of the following are components of nonspecific immunity EXCEPT (A) skin. (B) phagocytes. (C)complement. (D) lysozyme. (E) B cells.

46. Which of the following is true of T cells and B cells? (A) They are effector cells against specific pathogens. (B) They are produced from stem cells of the bone marrow. (C) They can help attack and destroy invading pathogens. (D) They typically have a short life span. (E) All of these statements are true.

47. In the Hardy-Weinberg equation , the genotype frequency of heterozygotes is represented by (A) p2 (B) 2pq (C) q2 (D)p2+q2 (E) p2 + 2pq

48. What mechanism leads to changes in allele frequencies due to random chance? (A) Genetic drift (B) Natural selection (C) Sexual selection (D) Neutral variation (E) inbreeding

49. A major disadvantage of using DNA or RNA sequences to identify species is that (A) it can only be used for sexually reproducing organisms. (B) it cannot be used for extinct species. (C) there are no rules for determining the number of sequence differences needed for a new species. (D) if can be misleading because many species exhibit large variation in phenotype. (E) it is expensive to sequence genomic DNA

50. Adaptive radiation is likely to have led to which of the following? (A) The divergence of a single pea aphid population into two distinct species. (B) The evolution of the horse via changes in climate and food supply. (C) The long period of equilibrium in a bat species in the Mariana Islands. (D) The 1,000 species of Drosophila found dispersed throughout the Hawaiian Islands. (E) A population of mountain goats are split because of the formation of a glacier.