59. Which of the following descriptions regarding muscle is correct?
(A) The length of thick filament will change in fully muscle contraction.
(B) A motor unit consists of multiple motor neurons and muscle fibers.
(C) Myoglobin binds oxygen tighter than hemoglobin does.
(D) Ca2+ binds with tropomyosin to initiate muscle contraction.
(E) Insect's skeletal muscles are grossly different from those of vertebrates.

55. Which of the following statements regarding John Gurdon's experiments for nucleus transfer is correct? (A) Frog eggs were enucleated by laser treatment. (B) Donor nucleus from frog intestine cells cannot be developed into a tadpole. (C) Donor nucleus from less differentiated cells are less likely to be developed into a tadpole. (D) He concluded that the more differentiated cells may generate changes in the nucleus. (E) None of the above.

56. In bird, the sex chromosome presented in egg, rather than sperm, determines the gender of the offspring. Therefore, females are ZW while males are ZZ. Which of the following statements is correct? (A) W linked recessive mutation will never cause disease in males. (B) Z linked recessive mutation will only affect female offspring. (C) Unfertilized egg cells only carry Z chromosome. (D) Some sperm cells carry W chromosome. (E) None of the above.

57. Which of the following descriptions regarding circulatory system is correct? (A) The circulatory fluid in closed circulatory system is called hemolymph. (B) Blood in right ventricle will first deliver to aorta. (C) Sinoatrial node is located in left atrium. (D) Erythropoietin is produced from kidney. (E) Mammals employ positive pressure breathing.

58. Which of the following descriptions regarding neuronal disorders is correct? (A) Amyloid plaques are always observed in schizophrenia. (B) Additive substances such as alcohol affect the dopamine regulation in brain. (C) Dopamine can be used to treat Alzheimer patients. (D) Parkinson's patients lost their ability to recognize people. (E) Depression is a rare nervous system disorder.

60. Radiolabelled isotope dating is an important method to determine the age of a fossil. A 14C content analysis of an animal fossil showed that its content is 0.01562 fold as much 14C as the atmosphere. The half-life of 14C is 5730 years. The age of the fossil is close to which of the following? (A) 1000 years (B) 5730 years (C) 35000 years (D) 70000 years (E) 100000 years

61. Which of the following descriptions about the Michaelis-Menten equation is false? (A) KM measures the substrate concentration at which the reaction rate is 1/2Vmax. (B) An enzyme with a low KM means that it has low affinity for its substrate. (C) An enzyme with a low kcat means that it has a low catalytic rate. (D) The turnover number, kcat, measures the rate of the catalytic process. (E) The ratio kcat/KM is a convenient measure of enzyme efficiency.

62. Which description about Hb (hemoglobin) is false? (A) HbF has an α2γ2 structure. (B) HbA has an α2β2 structure. (C) HbF has a much higher affinity for 2,3-BPG than HbA does. (D) 2,3-BPG lowers the O2 affinity of HbA. (E) 2,3-BPG is found inside red blood cells.

63. The carbon skeleton produced by transamination of aspartate enters the citric acid cycle as ______. (A) acetyl-CoA (B) pyruvate (C) fumurate (D) oxaloacetate (E) α-ketoglutarate

64. 5-phosphoribosyl-1-pyrophosphate (PRPP) is a precursor in the synthesis of all of the following products except ________. (A) histidine (B) tryptophan (C) arginine (D) UMP (E) AMP

65. In eukaryotic cells, mRNA modification includes __________. (A) splicing out exons and join introns (B) add a cap at 3’ end to protect the 3’ end (C) add a phosphate group at 5’ end to increase stability (D) remove nucleotides at 3’ end before addition of a poly A tail (E) remove 3’UU and attach CCA