61. Diversity of antibodies arises from which of the following?
(A) Assortment of V, D, J gene segments
(B) Junctional variation upon V-D or D-J joining
(C) Somatic mutation
(D) Assortment of heavy and light chain genes
(E) All of the above

57. Mammalian Toll-like receptors (TLRs) recognize macromolecules present on certain groups of pathogens. Which of the following is most likely to be recognized by TLR that defends against certain viruses? (A) lipopolysaccharides (B) double-stranded peptide (C) double-stranded RNA (D) gylcoproteins (E) phosphopeptides

58. Hemoglobin is responsible for transporting oxygen from lung to tissues. Bohr shift is one of the most important properties of hemoglobin. Which of the following is NOT true about Bohr shift? (A) Additional oxygen is bound by hemoglobin in lung when pH decreases. (B) Additional oxygen is released from hemoglobin at a lower pH. (C) Carbon dioxide is involved in Bohr shift. (D) Bohr shift helps tissues to obtain more oxygen in exercise. (E) None of the above.

59. Which of the following can maintain gene expression from lac operon? (A) High level of glucose from the breakdown of lactose (B) Lactose must binds to the operator (C) High level of cAMP in the presence of lactose (D) Repressor must binds to operator (E) Stop producing repressor

60. Animals release their nitrogenous waste in different forms. Which of the following statements are true ? ① Urea is excreted by many marine fishes. ② Ammonia is so toxic that it is rarely excreted as nitrogenous waste by any animals. ③ The animals in dry environment could excrete uric acid. ④ The form of nitrogenous waste is often an adaptation to animal habitats. (A)① ② ③ ④ (B) ① ② (C) ① ②④ (D) ②④ (E) ①③ ④

62. Genes A and B are linked on the same chromosome with recombination frequency of 20%. What will be the frequency of offspring with recessive phenotype from a cross between individuals with AB/ab and Ab/aB genotypes? (A) 20% (B) 10% (C) 6% (D) 4% (E) 2%

63. How does the occurrence of self-fertilization relative to cross-fertilization affect the fixation of an advantageous and recessive allele that newly arose in population by mutation? (A) The relative occurrence of self-fertilization does not affect the fixation of the allele. (B) The relative occurrence of self-fertilization affects the fixation of the allele only when the population is very small. (C) The allele will be fixed more quickly when the occurrence of self-fertilization is higher. (D) The allele will be fixed more quickly when the occurrence of self-fertilization is lower. (E) The allele will be fixed more quickly when the occurrence of cross-fertilization is higher.

64. Which of the following statements regarding inheritance is FALSE? (A) “Ture-breeding” means varieties for each self-fertilization produced offspring all identical to the parent. (B) The offspring of two different varieties are called hybrids. (C) A monohybrid cross is a breeding experiment in which the parental varieties differ in some characters. (D) The hybrid offspring of an F1 cross are the F2 generation. (E) The hybrid offspring of a cross are the F1 generation.

65. In a Hardy-Weinberg population with two alleles, A and a, that are in equilibrium. The frequency of aa individuals in the population is about 0.09. What is the frequency of individuals with Aa genotype? (A) 0.18 (B) 0.21 (C) 0.36 (D) 0.42 (E) 0.91

66. Which of the following statements regarding epigenetics is FALSE? (A) The study of inherited changes in genotype, especially in gene expression caused by the changes of DNA sequence. (B) Specific epigenetic processes include imprinting, gene silencing, X chromosome inactivation, and position effect. (C) Some regulation can be associated with microRNA. (D) Some regulation can be associated with DNA methylation. (E) Some regulation can be associated with histone modification

67. The difference between bacteria and archaea is (A) Membrane-enclosed organelles are present or not. (B) Circular chromosome. (C) Streptomycin inhibits growth. (D) Both A and C. (E) All of A, B, and C.