54. Which of the following descriptions regarding appetite control of animal is correct?
(A) Ghrelin is produced by small intestine.
(B) Leptin triggers the feelings of hunger.
(C) Insulin suppresses appetite by acting on intestine directly.
(D) PYY acts as appetite suppressant.
(E) None of the above.

50. How does a noncompetitive inhibitor decrease the rate of an enzyme reaction? (A) by binding to the active site of the enzyme, thus preventing binding of the normal substrate (B) by binding to an allosteric site, thus changing the shape of the active site of the enzyme (C) by decreasing the free-energy change of the reaction catalyzed by the enzyme (D) by acting as a coenzyme for the reaction (E) by binding to the substrate, thus changing its shape so that it no longer binds to the active site of the enzyme .

51. Which of the following statements regarding insects is correct? (A) Incomplete metamorphosis have a pupal stage. (B) Metamorphosis from the larval stages to the adult occurs during pupal stage. (C) Insects are analids. (D) Book lung is a special organ in insects. (E) Insects are lophotrochozoa.

52. Which of the following correctly describes the relationships between gross primary production (GPP), net primary production (NPP), autotrophic respiration (Ra), net ecosystem production (NEP) and total respiration of all organisms in the ecosystem (Rt)? (A) NPP = GPP - Rt (B) GPP = NPP - NEP (C) Rt + Ra + NPP = GPP (D) NPP = GPP - Ra (E) GPP = NEP + Rh

53. Which of the following statements regarding vertebrates is correct? (A) Chondrichthyans have operculum. (B) Amphibians are amniotes. (C) Marsupials have fully developed placenta. (D) Osteichthyans have swim bladders. (E) None of the above.

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.

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.

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