56. Testosterone functions inside a cell by _____.
(A) acting as a signal receptor that activates ion-channel proteins
(B) binding with a receptor protein that enters the nucleus and activates specific genes
(C) acting as a steroid signal receptor that activates ion-channel proteins
(D) becoming a second messenger that inhibits adenylyl cyclase
(E) coordinating a phosphorylation cascade that increases glycogen metabolism

52. A researcher found a method she could use to manipulate and quantify phosphorylation and methylation in embryonic cells in culture. One of her colleagues suggested she try increased methylation of C nucleotides in a mammalian system. Which of the following results would she most likely see? (A) increased chromatin condensation (B) decreased chromatin concentration (C) abnormalities of mouse embryos (D) decreased binding of transcription factors (E) inactivation of the selected genes

53. During splicing, which molecular component of the spliceosome catalyzes the excision reaction? (A) protein (B) DNA (C) RNA (D) lipid (E) sugar

54. A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates _____. (A) the blending model of genetics (B) true-breeding (C) dominance (D) a dihybrid cross (E) the mistakes made by Mendel

55. If cells in the process of dividing are subjected to colchicine, a drug that interferes with the functioning of the spindle apparatus, at which stage will mitosis be arrested? (A) anaphase (B) prophase (C) telophase (D) metaphase (E) interphase

57. Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large and complex lipids. Which cellular organelle must be involved in this condition? (A) the endoplasmic reticulum (B) the Golgi apparatus (C) the lysosome (D) mitochondria (E) membrane-bound ribosomes

58. Which of the following is an example of Batesian mimicry? (A) an insect that resembles a twig (B) a butterfly that resembles a leaf (C) a nonvenomous snake that looks like a venomous snake (D) a fawn with fur coloring that camouflages it in the forest environment (E) a snapping turtle that uses its tongue to mimic a worm, thus attracting fish

59. A patient who has a parasitic worm infection and another patient responding to an allergen such as ragweed pollen have which of the following in common? (A) an increase in cytotoxic T cell number (B) suffering from anaphylactic shock (C) risking development of an autoimmune disease (D) suffering from a decreased level of innate immunity (E) an increase in the levels of IgE

60. Endothermy is _____. (A) a characteristic of most animals found in tropical zones (B) a characteristic of animals that have a fairly constant body temperature (C) a term equivalent to cold-blooded (D) a characteristic of mammals but not of birds (E) seen only in insects and in certain predatory fishes

61. In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium, the frequency of the allele a is 0.3. What is the percentage of the population that is homozygous for this allele? (A) 0.09 (B) 0.49 (C) 0.9 (D) 9.0 (E) 49.0

62. By karyotype analysis, a woman is found to have 47 chromosomes, including one extra X chromosome. What kind of phenotype for her is expected? (A) normal female (B) sterile female (C) enlarged genital structures (D) albino (E) color blindness