61. The purpose of the hexose monophosphate shunt is to produce________.
(A) pentose phosphates and NADPH
(B) DNA and RNA
(C) fatty acids
(D) reducing substrates
(E) ATP

57. An unusual example of natural variation in the ploidy occurs in some species. Which of the following statements describes the endopolyploidy most correct? (A) The endopolyploidy is due to a cell division defect, and it occurs only in lower animals. (B) Endopolyploidy is the occurrence in somatic tissues； the most common is in human nerve and epidermal cells. (C) An example of endopolyploidy is in the salivary gland cells of Drosophila, the pairs of chromosomes double approximately 9 times. (D) The chromosomes undergo repeated rounds of chromosome replication without cellular division, the backup copies of chromosomes kept in vacuoles that segregated away from the functional copies. (E) The entire organism has extra copies of certain chromosomes, for producing additional gene products.

58.Drosophila is a model animal that is often used in genetic research. Which of the following is the best method for distinguishing the sex of Drosophila?(A) The Y chromosome plays a pivotal role in determining the male sex. Drosophila with Y chromosome is male, the rest is female. (B) Sex combs are located only on the forelegs of male, but not female Drosophila. (C) Male Drosophila is brighter and larger than female. (D) Male Drosophila has red eyes, and female Drosophila has white eyes. (E) Male Drosophila has curled wings, and female Drosophila has flat wings.

59. How do ADH and RAAS work together in maintaining osmoregulatory homeostasis? (A) ADH monitors osmolarity of the blood and RAAS regulates blood volume. (B) ADH monitors appropriate osmolarity by reabsorption of water, and RAAS maintains osmolarity by stimulating Na+ reabsorption. (C)ADH an RAAS work antagonistically； ADH stimulates water reabsorption during dehydration and RAAS removal of water when it is in excess in body fluids. (D) Both stimulate the adrenal gland to secrete aldosterone which increases both blood volume and pressure. (E)Only when they are together in the receptor sites of proximal tubule cells, will reabsorption of essential nutrients back into the blood take place.

60. Which of the following statements about the adrenal gland is correct? (A) During stress, TSH stimulates the adrenal cortex and medulla to secrete acetylcholine. (B) During stress, the alpha cells of islets secrete insulin and simultaneously the beta cells of the islets secrete glucagon. (C) At all times, the adrenal gland monitors calcium levels in the blood and regulates calcium by secreting the two antagonistic hormones, epinephrine and norepinephrine. (D) At all times, the anterior portion secretes ACTH, while the posterior portion secretes oxytocin. (E) During stress, ACTH stimulates the adrenal cortex, and neurons of the sympathetic nervous system stimulate the adrenal medulla.

62. Which integral membrane protein is uniquely found in the mitochondria of brown fat? (A) fatty acid synthase (B) catalase (C) ATP Synthase (D) UCP1 (E) FATP

63. What is the mode of action of Vancomycin? (A) Inhibition of cell wall biosynthesis (B) Inhibition of DNA biosynthesis (C) Inhibition of protein biosynthesis (D) Inhibition of folic acid biosynthesis (E) None of the above

64. Glycogen, amylose, and amylopectin are storage polysaccharides. Which one is linear form? (A) Glycogen (B) Amylose (C) Amylopectin (D) All of the above (E) None of the above

65. Which of the following statements about protein-ligand binding is correct? (A) The Ka is equal to the concentration of ligand when all of the binding sites are occupied. (B) The Ka is independent of such conditions as salt concentration and pH. (C) The larger the Ka (association constant), the weaker the affinity. (D) The larger the Ka, the faster is the binding. (E) The larger the Ka, the smaller the Kd (dissociation constant).

66. Which of the following is a heteropolysaccharide? (A) Cellulose (B) Chitin (C) Glycogen (D) Hyaluronate (E) Starch

67. The symptoms of severe combined immunodeficiency syndrome (SCID) are caused by a deficiency of which of the following enzymes? (A) adenine phosphoribosyltransferase (B) HGPRT (hypoxanthine-guanine phosphoribosyltransferase) (C) adenosine deaminase (D) dihydrofolate reductase (E) xanthine oxidase