Biochemistry Exam Questions, Exams of Biology

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BIOCHEMISTRY

1. Which of the following single-base DNA gene coding changes is least likely to significantly affect the function of resulting protein? (Harper pages 361-363) A. Missence mutation resulting to histidine-to-glutamic acid change B. Silent mutations in the third codon base C. Frameshift mutation D. Nonsense mutation
2. Which of the following is a property of enhancer elements? (Harper pages 384-385) A. They do not work located downstream of the promoter. B. They could work when located long distances from the promoter. C. Upon activation, they could repress transcriptional rate. D. They are proteins binding to DNA sequences.
3. Which of the following is considered as a transcriptional regulation control? (Harper pages 383) A. Chromatin remodelling B. Alternative splicing C. RNA editing D. Capping of the mRNA
4. Which of the following is true of biological membrane structure? (Harper pages 415-421) A. Saturated fatty acids increase fluidity. B. Cholesterol is an amphipathic molecule. C. The inner and outer sheets are symmetrical to each other. D. They contain transport proteins, which are mainly peripheral.
5. Which of the following defines the specificity of hormone activity in a cell? (Harper page 435) A. The synthesis of the hormone in the target cell B. The presence of the hormone receptor C. The upregulation of the hormone receptor in a cell D. Absence of other target cells adjacent to hormone-producing cells
6. Which of the following is true of hormones? (Harper pages 437-38) A. Hormones with intracellular receptors are usually hydrophilic. B. Lipophilic hormones need transport proteins. C. Cathecholamines and steroid hormones act via a plasma membrane receptor. D. Steroid hormones are derivatives of amino acids.

7. Which vitamin is essential for one-carbon metabolism? (Harper page 494) A. Thiamine B. Riboflavin C. Niacine D. Folic acid
8. Which of the following correctly characterize a component of the extracellular matrix? (Harper 535-541) A. Collagen type IV, a component of the basement membrane, form compact bundles. B. Elastin is essential for cell-cell communication. C. Fibronectin is involved mainly in cell adhesion and signaling. D. Laminin acts intracellularly as a major component of the cytoskeleton.
9. Which of the following is NOT correctly paired? (Harper page 593) A. IgA: found in secretions B. IgM: transplacental passage C. IgG: opsonization D. IgE: allergic responses
10. Which of the following statements characterizes ATP? (Harper page 84) A. It is used in the synthesis of DNA. B. It contains 3 phosphate bonds for energy storage. C. It is used to drive thermodynamically unfavorable reactions. D. It is produced mainly by substrate level phosphorylation.
11. Enzymes, as biological catalysts accelerate velocity of reactions by: A. lowering the free energy of activation of reactions B. increasing transition state of reactants and products C. lowering the net energy change between initial and final states of the reaction D. increasing the equilibrium constant (Keq) of the reaction
12. A general class of enzymes that join molecules by creating a new chemical bond at the expense of ATP hydrolysis A. lyase B. isomerase C. ligase D. hydrolase
13. An enzyme catalyzing the reaction: lecithin + cholesterol -- fatty acid cholesterol ester + lysolecithin is classified as: A. oxidoreductase B. lipase C. transferase D. hydrolase
14. The Michaelis Menten constant is equal to substrate concentration when: initial velocity is ½ Vmax Vmax is doubled Km= ½ substrate concentration Km/Vmax = 1

15. The kinetic parameter that reflects the affinity of the enzyme for its substrate is called: A. Vmax B. Q C. Km D. Kcat
16. Double reciprocal plot of the Michaelis Menten equation is called: A. Hanes-Wolf B. Eadie Hofstee C. Lineweaver Burk D. Briggs-Haldane
17. In the Lineweaver Burk plot, the slope of the line is equal to: A. -1/Km B. Km/Vmax C. 1/Vmax D. 1/S
18. Which statement is true about competitive inhibition? A. Inhibitor binds to the allosteric site of the enzyme B. Km is constant while Vmax decreases C. Usually the inhibitor structurally resembles the normal substrate D. Both the Km and Vmax decrease
19. Serum enzymes are elevated following tissue injury and death due to: A. enzyme induction secondary to stimulation of protein synthesizing machinery of the cell B. allosteric enzyme activation by positive activators C. increased cell membrane permeability and leakage of enzymes into blood D. proteolytic activation of proenzymes or zymogens
20. Which of the following coenzymes is not appropriately paired with the enzymatic reaction it is associated with? E. tetrahydrofolate- transamination F. biocytin-carboxylation G. NAD- dehydrogenation H. Coenzyme A- transacylation
21. The active form of Vitamin B12 coenzyme: A. 5’-deoxyadenosylcobalamin B. hydrocobalamin C. aquocobalamin D. cobamide
22. In Bioenergetics, the amount of energy available for the performance of useful work is termed: A. entropy B. free energy C. enthalpy D. equilibrium energy

23. During biological oxidations, reduced coenzymes such as NADH and FADH 2 generate energy when oxidized thru the: A. Krebs Cycle B. Electron Transport Chain C. Cytochrome P450 system D. Embden Meyerhof Pathway
24. The final acceptor of electrons in the Respiratory Chain is: A. cytochrome oxidase B. coenzyme Q C. iron sulfur center D. oxygen
25. Substrate level phosphorylation differs from oxidative phosphorylation in that: A. oxidative phosphorylation synthesizes ATP via the Electron Transport Chain B. substrate level phosphorylation only takes place in the cytosol C. oxidative phosphorylation is coupled to a direct transfer of high energy ~Pi from a high energy compound to ADP D. Substrate level phosphorylation is more energy efficient per molecule of substrate oxidized
26. Which of the following affects biological oxidation by dissociating mitochondrial respiration from phosphorylation? A. 2,4 dinitrophenol B. B. rotenone C. C. antimycin D. cyanide
27. Which of the following statements is correct regarding digestion of carbohydrates? A. Digestion of dietary polysaccharides takes place to a significant extent in the stomach due to acid hydrolysis. B. Digestion initially takes place in the mouth through the action of - amylase. C. Pancreatic amylase hydrolyzes -1,4 glycosidic linkages in cellulose. D. The final end products of digestion are all glucose molecules from dietary carbohydrates
28. In man, glucose from dietary cellulose could not be available for energy because: A. cellulose is made up of very long polysaccharide chain made up of  1,4 and  1,6 glycosidic bonds B. human diet does not have a significant amount of cellulose C. man inherently lacks enzyme to hydrolyze cellulose D. cellulose is not made up of glucose units
29. A 3 month old infant develops diarrhea and abdominal discomfort a following a milk formula. However feeding history revealed that he was able to tolerate breast feeding and the same milk formula at birth. The most likely condition is A. Primary - galactosidase deficiency B. Milk allergy C. Lactose malabsorption D. Secondary lactose intolerance

30. The major pathway of glucose metabolism that exists in all cells is the: A. Pentose Phosphate Pathway B. Citric Acid Cycle C. Uronic Acid Pathway D. Embden Meyerhof Pathway
31. Hexokinase differs from glucokinase in which aspect? A. Glukokinase has a higher affinity to glucose B. Hexokinase is induced by insulin C. Glucokinase phosphorylates glucose to glucose 6 phosphate D. Hexokinase is inhibited by glucose 6 phosphate
32. The end product of glycolysis in exercising muscle and red blood cells is: A. pyruvic acid B. acetic acid C. lactic acid D. acetoacetic acid
33. The most important positive regulator of the committed step of glycolysis is the availability of A. fructose 1,6 bisphosphate B. ATP C. Citrate D. fructose 2,6 bisphosphate
34. True of the The Malate Aspartate Shuttle A. can be considered as an anaplerotic reaction B. less energetically efficient than the  glycerophoshate shuttle C. transports NADH from the cytosol into the mitochondria for oxidative phosphorylation D. provides reducing equivalents for reductive biosynthesis of fats
35. The initial step in the TCA Cycle is catalyzed by: A. pyruvate dehydrogenase B. lactate dehydrogenase C. citrate synthase D. -keto-glutarate dehydrogenase
36. The Hexose Monophosphate Shunt is metabolically significant to nucleic acid metabolism because it: A. provides NADPH B. furnishes pentose phosphates C. is an alternative pathway for glycolysis D. stabilizes structure of DNA
37. The rate limiting step in the Pentose Phosphate Pathway is catalyzed by: A. hexokinase B. glucose-6 phosphate dehydrogenase C. 6- phosphogluconolactonase D. transketolase
38. Which of the following enzymatic reaction is common to both glycolysis and gluconeogenesis? A. hexokinase B. pyruvate carboxylase C. phosphofructokinase 1 D. phosphotriose isomerase

39. The inherent absence of this enzyme prevents muscle glycogenolysis to maintain glucose homeostasis: A. glycogen phosphorylase B. glucose- 1- phosphatase C. glucose-6-phosphatase D. UDP-Glucose pyrophosphorylase
40. Glycogen synthesis is activated while glycogenolysis is inhibited when: A. glucagon/ insulin ratio is elevated B. glycogen synthase is covalently modified by phosphorylation C. cyclic AMP dependent protein kinase is activated D. glycogen synthase I predominates over glycogen synthase D
41. Mannose and Fructose enter the mainstream of carbohydrate metabolism via: A. Citric Acid Cycle B. Embden Meyerhoff Pathway C. Hexose Monophosphate Shunt D. Glyoxylic Acid Cycle
42. Fatty acids enter the mitochondrial matrix for oxidation in what form? A. acyl-CoAs through active transport B. as free fatty acids C. following conversion to carnitine D. complexed with carnitine as acyl-carnitine
43. The number of reduced electron carriers generated when one mole of palmitate is subjected to oxidation: A. 2 FADH 2 and 3 NADH + H+ B. 3 FADH 2 and 2 NADH + H+ C. 7 FADH 2 and 7 NADH + H+ D. 5 FADH 2 and 5 NADH + H+
44. Majority of the reducing equivalents necessary for fatty acid biosynthesis are generated during conversion of: A. 1,3 bisphosphoglycerate to 3 phosphoglycerate B. pyruvate to malate C. glucose 6-phosphate to 6 phosphogluconate D. 6 phosphogluconate to ribulose 5-phosphate
45. How many moles of NADPH + H+^ can be derived from the pathway utilized in the transport of acetyl CoA out of the mitochondria? A. 8 moles B. 10 moles C. 12 moles D. 14 moles
46. The site of action of the NSAIDS is: A. thromboxan synthase B. prostaglandin cyclooxygenase C. lipoxygenase D. prostacyclin synthase

47. Hepatocytes contribute to the overall body content of ketone bodies primarily because of the absence of: A. β-ketothiolase necessary to hydrolyze acetoacetyl CoA B. HMG-CoA lyase C. HMG-CoA synthetase D. 3-ketoacyl-CoA transferase or acetoacetate succinyl CoA transferase
48. The principal plasma carrier of dietary triacylglycerols is: A. serum albumin B. LDLs C. HDLs D. chylomicrons
49. Activation of lipoprotein lipase requires which apoprotein? A. Apo E B. Apo B- C. Apo C-II D. Apo B-
50. VLDLs are synthesized in the liver for transport of which of the following to the peripheral tissues? A. triacylglycerols B. apoproteins for HDL synthesis C. LDL receptors D. apo B-
51. The committed step of cholesterol biosynthesis is catalyzed by this enzyme: A. squalene synthase B. HMG CoA reductase C. mevalonate kinse D. HMG CoA lyase
52. High dietary intake of cholesterol leads to: A. increased HMG CoA reductase synthesis B. decreased apo B-100 synthesis C. decreased ACAT activity D. decreased LDL receptor synthesis
53. Several of the enzymes of cholesterol biosynthesis require which of the following cofactors? A. biotin B. NADPH C. FADH 2 D. TPP
54. The molecule that helps stabilize the action of pancreatic lipase on dietary lipids: A. colipase B. chenodeoxycholic acid C. cholic acid D. enteropeptidase

55. Source of the nitrogen atoms required for animal metabolism can be directly obtained from: A. atmospheric nitrogen B. NO 2 C. ammonia D. nitric oxide
56. Aside from urea, the main circulatory system carrier of nitrogen atoms destined for excretion by the kidney is: A. glutamate B. asparagine C. alanine D. glutamine
57. A deficiency in the abilty to secrete enterokinase leads to which of the following? A. abnormally low levels of intestinal zymogens B. abnormally low levels of active intestinal proteases C. abnormally low levels of undigested proteins in lower GIT D. increase plasma levels of serum amylase
58. Transamidation reaction include which of the following? A. formation of liver glutamate from α-ketoglutarate B. formation of liver glutamine from glutamate C. formation of liver asparagine from aspartate D. formation of liver oxaloacetate from alanine
59. The important cofactor for the transaminases: A. pyridoxal phosphate B. tetrahydrofolate C. biocytin D. tetrahydrobiopterin
60. The production of alanine by peripheral tissue, especially by the muscle, is primarily dependent on: A. allosteric effectors of ALT B. intracellular levels of pyruvate C. intracellular levels of glutamate D. intracellular levels of NADH
61. Nitrogen of muscle alanine can be derived from tissue ammonia through this enzyme action: A. glutamate dehydrogenase B. alanine dehydrogenase C. glutamine synthetase D. alanine synthetase
62. Sulfur for cysteine synthesis is derived from : A. sulfites B. H 2 S C. Coenzyme A D. methionine
63. Severe PKU and shortened life span is a result of: A. excess dietary phenylalanine B. excess dietary tyrosine C. deficiency of dihydrobiopterin reductase

D. deficiency of tetrahydrofolate

64. Serine is synthesized by: A. transamination of an amino acid with α-ketoglutarate as an amino acceptor B. transamination of an α-ketoacid derived from TCA C. transamination of an α-ketoacid derived from EMP D. modification of an essential amino acid
65. Lysine is an essential amino acid because: A. animals cannot make the lysine carbon skeleton B. the ε-amino group of lysine cannot be formed by an aminotransferase C. the α-carboxylic cannot be added to urocanate D. lysine cannot be subjected to deamidation
66. Amino acids that are strictly ketogenic: A. lysine and leucine B. leucine and isoleucine C. valine and isoleucine D. tyrosine and tryptophan
67. Choose the correct precursor-product relationship from the following: A. tyrosine is a precursor to dihydroxyphenylalanine B. tyrosine is a precursor to melatonin C. melatonin is a precursor of serotonin D. dopamine is a precursor to norepinephrine
68. The Watson-Crick model or the B-form of DNA is typified by: A. 12 base pairs per helical turn B. a smaller number of purines than pyrimidines C. bases located in the interior of the right-handed helix D. two single strands that run in the 5’ 3’ direction
69. Guanine-cytosine (G-C) base pairs in a DNA molecule are more stable to denaturation than adenine-thymine (A-T) pairs because: A. adenine and thymine have bulkier structures than guanine and cytosine B. A-T base pairs exhibit less electron clouds around them C. G-C base pairs contain more hydrogen bonds than A-T pairs D. the phosphodiester bonds among G-C base pairs are weaker
70. DNA is distinguished from RNA by: A. a high content of modified bases B. its component sugar, ribose C. its single stranded structure D. the presence of thymine instead of uracil
71. Anticancer drugs like 5-fluorouracil and 6-mercaptopurine act against malignant cells by: A. being incorporated into DNA before replication B. causing the denaturation of DNA in cancer cells C. inactivating protein synthesis D. inhibiting the enzymes that synthesize thymidylic acid

72. Which of the following is a nucleotide? A. uracil B. cytidine C. guanosine D. adenylic acid
73. Which vitamin is essential in the synthesis of purine nucleotides? A. ascorbic acid B. folic acid C. niacin D. thiamin
74. Which clinical condition does not involve a defect in purine metabolism? A. adenosine deaminase deficiency B. gout C. Lesch-Nyhan syndrome D. orotic aciduria
75. Salvage reactions that generate purine and pyrimidine nucleosides and nucleotides are characterized as: A. involving the same enzymes as in de novo synthesis B. more efficient than nucleotide synthesis from new precursors C. providing greater output of purines and pyrimidines D. requiring less energy than does the de novo synthesis
76. The enzyme that catalyzes the committed step of purine nucleotide de novo pathway: A. carbamoyl phosphate synthetase I B. glutamine amidophosphoribosyl transferase C. carbamoyl phosphate synthetase II D. aspartate transcarbamoylase
77. In the management of gout, allopurinol is given to inhibit xanthine oxidase, the enzyme that catalyzes the synthesis of: A. allantoate B. ammonia C. urea D. uric acid
78. The correct flow of genetic information according to the Central Dogma of Molecular Biology is: A. replication -----> transcription ----> translation B. replication -----> translation ----> transcription C. transcription ---- > replication ----> transcription D. translation ----> replication ----> transcription
79. Transfer RNA (tRNA) as an adaptor molecule serves to: A. carry the nucleotide sequences that will dictate the amino acid to be synthesized B. hold the promoter site that will be recognized by the polymerase C. recognize the triplet codon in mRNA via its anti-codon arm D. synthesize the amino acid to be incorporated into the peptide

80. Degeneracy of the Genetic Code means that: A. an amino acid can only be decoded by a single codon B. a single codon encodes only one amino acid C. multiple codons may encode the same amino acid D. with time, codons degenerate into senseless code
81. The final product of gene expression is: A. amino acid B. nucleotide C. polynucleotide D. protein
82. Normal growth and development of cells are controlled by genes known as: A. leader genes B. non-coding genes C. proto-oncogenes D. transforming genes
83. The type of mutation that involves the substitution of a purine base with another purine base is: A. transition B. transposition C. transpyrimidation D. transversion
84. This mineral helps guard against DNA damage as a cofactor of glutathione: A. iron B. manganese C. selenium D. zinc
85. A tool in molecular biology in which a DNA sequence of interest is exponentially amplified in vitro by repeated cycles of enzymatic DNA synthesis is: A. DNA sequencing B. in situ hybridization C. Northern blotting D. polymerase chain reaction
86. In the construction of recombinant DNA, which enzyme is used to cut DNA at precise base sequences? A. DNA polymerase B. DNA-RNA exonuclease C. restriction endonuclease D. T4 DNA ligase
87. In recombinant DNA technology, antibiotic resistance genes in plasmids are used to: A. control copy number in bacteria B. facilitate transformation of host cells C. provide a marker for start of replication D. select and screen for recombinant DNA clones

88. The pain felt by a patient with an enlarging malignant tumor is partly contributed by the: A. exaggerated metabolism of nutrients by the tumor cells B. loss of enzymes for glucose oxidation in cancer tissue C. release of cytokines such as IL-1 and IL-6 by the tumor cells D. overgrowth of blood vessels in the interior of the cancer mass
89. Malignancy may be naturally prevented if the mutated cancer gene was repaired: A. after gene expression B. before DNA replication C. following transcription D. shortly after DNA synthesis
90. With persistence of a mutation in cells during organogenesis, the resulting event is: A. development of cancer B. inactivation of genetic disorders C. occurrence of physical malformations D. promotion of sterility
91. To specifically identify the mutation in the affected DNA segment in a patient with cancer, which blot transfer method should be used? A. Northern B. Southern C. Southwestern D. Western
92. The enzyme, Taq polymerase is used in Polymerase Chain Reaction (PCR) because it: A. facilitates annealing of primers B. is resistant to heat denaturation C. promotes DNA polymerization D. provides optimum condition for DNA synthesis
93. A 60-year-old woman has developed red, roughened skin in sun- exposed areas over the past 2 years. She also has a chronic, watery diarrhea. On physical examination she exhibits memory loss with confusion. These findings are most consistent with which of the following vitamin deficiencies? A. Thiamine B. Pyridoxine C. Niacin D. Vitamin A
94. A clinical study is performed involving dietary iron metabolism in adults. It is observed that intestinal absorption of iron can be enhanced in patients with iron deficiency anemia by supplementing their diet with another nutrient. Which of the following vitamins is most likely to have this effect? A. D B. E C. C D. B

95. A 6-year-old child was born at term, with no congenital anomalies. She is now only 70% of normal body weight, though she shows dependent edema of the lower extremities as well as an enlarged abdomen. Her flaking skin shows irregular areas of depigmentation, hyperpigmentation, and desquamation. These findings are most suggestive of which of the following nutritional problems? A. Marasmus B. Kwashiorkor C. Niacin deficiency D. Vitamin A Deficiency
96. A 41-year-old man has had increasing dyspnea for the past year. On physical examination he has diffuse crackles at lung bases. A chest x-ray shows pulmonary edema and cardiomegaly. Echocardiography shows an ejection fraction of 40%. Laboratory studies show hemoglobin 14 g/dL, hematocrit 42%, and WBC count 8320/microliter. A deficiency in which of the following vitamins is most likely to produce these findings? A. A B. B C. B D. K
97. A 7-year-old child has complained of pain in his legs for the past year. On physical examination, there is bowing deformity of his lower extremities. Plain film radiographs of his lower legs shows widened epiphyses and bowing of tibiae. Bone mineral density appears normal, consistent with failure of osteoid matrix formation. Which of the following vitamin deficiencies is this child most likely to have? A. D B. E C. C D. B
98. A 28-year-old man has a history of multiple and recurrent pulmonary infections since childhood. He also has noted foul smelling stools for the past 10 years. Laboratory studies show an elevated sweat chloride test. He has a quantitative stool fat of 10 g/day. A deficiency state involving which of the following nutrients is most likely to develop in this patient? A. Vitamin B B. Vitamin D C. Calcium D. Vitamin A
99. A clinical study is performed to compare the risk for health problems in obese persons with a BMI OF 35, compared with a control group of persons with a BMI between 20 and 25. Persons in these two groups are followed for 20 years. Which of the following conditions is most likely to appear equally in both groups? A. Cholelithiasis B. Cirrhosis C. Hypertension D. Diabetes mellitus

100. A 15-year-old girl has been under a physician's care for the past year after diagnosis of anorexia nervosa. Her BMI is now 18. On physical examination she has cheilosis. Laboratory studies show hemoglobin 13. g/dL, hematocrit 41.0%, MCV 88 fL, platelet count 191,055/microliter, and WBC count 4930/microliter. Her serum glucose is 66 mg/dL. Which of the following nutrient deficiencies is most likely to cause this patient's findings? A. Riboflavin B. Vitamin C C. Folic Acid D. Iron
101. The metabolic function of the pentose phosphate pathway is to: A. act as a source of ADP biosynthesis. B. generate NADPH and pentoses for the biosynthesis of fatty acids and nucleic acids. C. participate in oxidation-reduction reactions during the formation of H 2 O. D. provide intermediates for the citric acid cycle.
102. The FNRI Philippine RENI Committee 2002 recommends the following protein intake: A. 1.14 g/kg DBW/day B. 2.14 g/kg DBW/day C. 3.14 g/kg DBW/day D. 4.14 g/kg DBW/day
103. Number of moles of ATP generated from the complete oxidation of pyruvate as it undergoes the pyruvate dehydrogenase reaction and the Kreb’s cycle is: a. 12 c. 14 b. 13 d. 15 Page 113 Harper’s 26th^ Edition Chapter 16
104. Which of the following enzymes when deficient wil result in the accumulation of gangliosides in patients suffering for Tay Sach’s Disease? a. glucocerebrosidase c. sphingomyelinase b. aryl sulfatase d. hexosaminidase Page 203 Harper’s 26th^ Edition Chapter 24
105. Which of these is deficient in Cori’s disease? a. glucose-6-phosphate c. branching enzyme b. glycogen phosphorylase d. debranching enzyme Page 152 Harper’s 26th^ Edition Chapter 18
106. Just before breakfast, what is the source of glucose in the body? a. glucose c. ketones b. glycogen d. fatty acids Page 102,107-108 Harper’s 26th^ Edition Chapter 13
107. For every mole of glucose that goes through the glycolytic pathway, what is the net number of pyruvate generated? a. one c. three b. two d. four Page 136-144 Harper’s 26th^ Edition Chapter 17

108. Which of these is the primaryfunction of the Pentose Phosphate Pathway? a. generation ATP b. NADPH generation c. NADPH generation and production of ribose residues d. Provision of ribose residues of nucleotide and nucleic acid synthesis Page 163-168 Harper’s 26th^ Edition Chapter 20
109. Which enzyme generates NADPH + H needed to reduce GSSG: a. glutathione reductase c. aldehyde dehyrogenase b. glucose 6PO 4 dehydrogenase d. lactate dehydrogenase Page 156-165 Harper’s 26th^ Edition Chapter 19
110. Glucose 6 phosphate dehydrogense deficiency is characterized by which one of the following? a. accumulation of glucose -6-phosphate in the tissue b. decreased formation of NADPH c. increased synthesis of reduced glutathione d. may manifest as hemorrhagic anemia Page 169-170 Harper’s 26th^ Edition Chapter 20
111. The Citric acid cycle as the final common pathway in fuel metabolism provides greatest amount of energy by being directly linked to: a. glycerophosphate shuttle c. glycolysis b. malate aspartate shuttle d. electron transport chain Page 130-133 Harper’s 26th^ Edition Chapter 16
112. Cyanide poisoning is very fatal. This is bacuse cyanide has this effect of the Electron Transport Chain: a. inhibits complex III b. inhibits cytochrome oxidase c. uncouples oxidative phosphorylation d. ienhance the transport of electrons Page 92 Harper’s 26th^ Edition Chapter 12
113. At high concentration of blood glucose, as in uncontrolled diabetes mellitus, hemoglobin reacts with glucose to form this compound which can be assayed to monitor glycemic control a. methemoglobin b. hemochrome c. glycosylated hemoglobin d. hemin Page 47 Harper’s 26th^ Edition Chapter 6
114. The precursor of the sugar-phosphate moieties in the de novo synthesis of both purine and primidine nucleotide is: a. glucose 1 phosphate b. glucose 6 phosphate c. ribose 1 phosphate d. ribose 5 phosphate Page 286-292 Harper’s 26th^ Edition Chapter 33
115. The highest reservior of calories in muscle tissues is: a. Fats c. glycogen b. proteins d. ketone bodies Page574-576 Harper’s 26th^ Edition Chapter 49

116. cAMP exert its effect as a second messenger by: a. inducing release of cytokines b. activating Protein Kinase C c. activating cyclic adenylase d. activating Protein Kinase A Page 457-468 Harper’s 26th^ Edition Chapter 43
117. Deficiency in the intake of carbohydrates and fats can lead to: a. increase in protein requirements b. increase intake of calories c. increase deposition of fats d. decrease in the catabolism of body proteins Page 478-479 Harper’s 26th^ Edition Chapter 44
118. Gluconeogenesis is the major source blood sugar during: a. the fed state c. prolonged fasting b. periods between meals d. early refed state Page 158-161 Harper’s 26th^ Edition Chapter 19
119. Melatonin is a specialized product of tryptophan that is involved with a. pigment formation c. circadian rhythm b. vasodilatation d. thyroid gland secretion Page 267 Harper’s 26th^ Edition Chapter 31
120. The receptor involved in the G-protein coupled signal transduction pathway: a. tyrosine kinase receptor c. β adrenergic receptor b. guanylyl cyclase receptor d. janus kinase receptor Page 459,464-465 Harper’s 26th^ Edition Chapter 43
121. Dinitrophenol (DNP) and other uncouplers which uncouple oxidation and phosphorylation are useful weight losing agents. They prevent ATP sysnthesis in the Electron Transport Chain by which of the following mechanism? a. Electron Transport is blocked b. Protons build up in the intermembrane space c. There is reduced availability of ADP d. The electrochemical gradient is dissipated Page 95-96 Harper’s 26th^ Edition Chapter 12
122. The most active form of vitamin D is: a. 1,25 dihydroxycholecalciferol c. ergocalciferol b. vitamin D 3 d. 7- dehydrocalciferol Page 484-486 Harper’s 26th^ Edition Chapter 45
123. Plant fat is high in unsaturated fatty acids compared to animal fat. Which one of the following characteristics BEST describes unsaturated fatty acids in contrast saturated fatty acids? a. lower rate of oxidation b. lower rate of melting point c. less water soluble d. more solid at room temperature Page 144 Harper’s 26th^ Edition Chapter 14

124. This is the mechanism of action by which penicillin kills bacterial cells: a. it inhibits bacterial DNA replication b. it acts as an allosteric inhibitor to the enxzyme reverse transcriptase c. it is an analogue of D-phe-D-phe effectively preventing the synthesis of tetrahydrofolates d. it covalently binds to the active site of the enzyme for cell wall synthesis Page 371-372 Harper’s 26th^ Edition Chapter 38
125. An attack of acute asthma has been attributed to leukotrienes. Which of the following statements is TRUE regarding leukotrienes? a. produced mainly in the nervous tissue b. components of slow reacting substance of anaphylaxis c. descrease vascular permeability d. inhibit the release of lysosomal enzymes Page 194-196 Harper’s 26th^ Edition Chapter 23
126. This statement accurately describes Vitamin K: a. Menaquinone-7 is the major form of Vitamin K found in plants b. It is found only in green leafy vegetables while intestinal bacteria are not able to synthesize it c. It functions as a cofactor to a carboxylase that acts on glutamate residues of clotting factor precursors proteins d. It main function is to protect the erythrocytes Page 486 Harper’s 26th^ Edition Chapter 45
127. Bilirubin is an important endproduct during the course of hemolysis. Which of the following statements is TRUE regarding bilirubin? a. excreted from the liver in the form of bilirubin diglucuronides b. conjugation mainly it takes place in the kidneys c. unconjugated bilirubin is readily excreted in the urine d. unconjugated hyperbilirubinemia due to complete obstruction of the common bile ducts is generally accompanied by increased urobilinogen in the urine Page 280-284 Harper’s 26th^ Edition Chapter 32
128. Kwashiorkor occurs when there is: a. lack of calories in the diet b. lack of calories from protein in the diet c. lack of carbohydrates and protein in the diet d. lack of all the macro and micro nutrients in the diet Page 237,478-479 Harper’s 26th^ Edition Chapter 28 , 44
129. Cancer can be attributed to mutation in the DNA. A mutation that converts an amino acid codon to a stop codon is: a. silent c. missense b. frameshift d. nonsense Page 362 Harper’s 26th^ Edition Chapter 38
130. The process by which a polypeptide’s destination in the cell is determined by which of these? a. Codons c. signal peptides b. molecular chaperones d. signal recognition particles Page 498,503-504,508 Harper’s 26th^ Edition Chapter 46

131. Which of the following histones is uniquely associated with the linker DNA? a. H 3 c. H 4 b. H 1 d. H 2 A Page 314-315 Harper’s 26th^ Edition Chapter 36
132. Which of the following is a nucleoside? a. guanylic acid c. guanosine 5’-monophosphate b. dUMP d. cytidine Page 286-287 Harper’s 26th^ Edition Chapter 33
133. Which of the following about the salvage pathway of purine nucleotide synthesis is correct? a. Deficiency of hypoxanthine-guanine phosphoribosyl transferase is the cause of Lesch-Nyan syndrome b. The rate limiting enzyme is PRPP amidotransferase c. The donor of the ribose 5-phosphate is the HMP shunt d. The salvage pathway for the free bases require more ATP than the novo sysnthesis of purine nucleotide Page 294 Harper’s 26th^ Edition Chapter 34
134. An individual who has fasted for more than 24 hours will have an increased production of which amino acids in his tissues? a. aspartate and glutamine b. glutamate and asparagine c. valine, isoleucine and leucine d. glutamine and alanine Page 14-20 Harper’s 26th^ Edition Chapter 3
135. Which amino acid is purely ketogenic? a. leucine c. isoleucine b. tryptophan d. proline Page 15,259-260 Harper’s 26th^ Edition Chapter 3,
136. Kwashiorkor occurs when there is: a. lack of calories in the diet b. lack of calories from protein in the diet c. lack of carbohydrates and protein in the diet d. lack of all the macro and micro nutrients in the diet Page 478-479 Harper’s 26th^ Edition Chapter 44
137. This amino acid is the source of most of the blood glucose during starvation: a. glutamine c. glutamate b. alanine d. aspartate Page 236 Harper’s 26th^ Edition Chapter 27
138. Allopurinol is used in gout bacause it is an allosteric inhibitor of xathine oxidase which is responsible for synthesizing this excretory metabolite of purines: a. allanton c. urea b. uric acid d. ammonia Page 301 Harper’s 26th^ Edition Chapter 35

139. The catecholamines, epinephrine and dopamine are synthesized from this amino acid: a. tyrosine c. arginine b. isoleucine d. threonine Page 445 Harper’s 26th^ Edition Chapter
140. Which of the following is the most important role of amino acids in the body? a. source of energy b. precursor of nonprotein nitrogen containing substances c. building blocks of tissue protein d. precursor glucose Page 249 Harper’s 26th^ Edition Chapter 30
141. Most of the ammonia that are used for the synthesis of urea are directly derived from the deamination of: a. leucine c. isoleucine b. aspartic acid d. glutamic acid Page 243-244 Harper’s 26th^ Edition Chapter 29
142. A person suffering from gout should decrease his intake of: a. bread c. egg b. banana d. sardines Page 229 Harper’s 26th^ Edition Chapter 26
143. Most of the function membranes are accomplished by: a. proteins c. carbohydrates b. phospholipids d. cholesterol Page 416-417 Harper’s 26th^ Edition Chapter 41
144. Which statements is BEST describes the arrangement of proteins and lipids in membranes? a. Protein form a continous sheet on either side of the phospholipid bilayer b. Proteins occur in the lipid bilayer as discontinous particles c. Protein molecules are sandwiched between the exoplasmic and cytoplasmic lipid monolayers d. Lipid molecules “float” on a sea proteins Page 416-417 Harper’s 26th^ Edition Chapter 41
145. Excessive ingestion of raw eggwhite is detrimental because it inhibits this step in extramitochondrial lipogenesis: a. formation of malonyl CoA c. reduction step b. binding of malonyl to acyl carrier protein d. deacylation reaction Page 173-174 Harper’s 26th^ Edition Chapter 21
146. Gelatin has a high collagen content. It is not a good source of protein because: a. collagen contains a limited variety of amino acids b. collagen cannot be digested c. too much collagen causes brittle bones d. collagen contains more sugars than amino acids Page 38 Harper’s 26th^ Edition Chapter 5

147. Semi-conservative replication of DNA means: a. DNA systhesis occurs one strand at a time b. Each new DNA strand forms a pair with the template strands c. The two new DNA strands pair with each other d. Duplication occurs in opposite direction in two strands Page 306-307 Harper’s 26th^ Edition Chapter 35
148. Which of the following is the BEST describes the action of 5 FU in the treatment of cancer? a. inhibits synthesis of DNA b. inhibits protein synthesis c. depletes the cancer cells of necessary nutrients like vitamins d. depletes the cancer cells of required oxygen Page 328-330 Harper’s 26th^ Edition Chapter 36
149. Which one of the following is true regarding RNA? a. Messenger RNA contain peculiar bases b. The codon is found in trasfer RNA c. Ribosomal RNA contain the anticodon d. Transfer RNA carries the amino acid Page 306-312,341-357 Harper’s 26th^ Edition Chapter 35,
150. During DNA replication, which enzyme joins Okazaki fragments? a. topoisomerase c. DNA ligase b. RNAase II d. helicase Page 328 Harper’s 26th^ Edition Chapter 36
151. Degeneracy of the genetic code denotes the existence of: a. multiple codons for a single amino acid b. codons consisting only of 2 bases c. base triplets that do not code for any amino acid d. codons that include one or more of the “unusual” bases Page 359 Harper’s 26th^ Edition Chapter 38
152. In the normal resting state of humans, muscles will mainly use up energy provided by: a. carbohydrates c. fats b. branced chain amino acids d. muscle glycogen Page 574-576 Harper’s 26th^ Edition Chapter 49
153. Familial hypercholesterolemia is due to a. deficiency or defective LDL receptors b. mutation on HMG-CoA reductase c. increased dietary intake of cholesterol d. decreased excretion of cholesterol Page 228 Harper’s 26th^ Edition Chapter 26
154. Which of the following is the most metabolically active plasma lipid? a. nonesterified fatty acid c. free cholesterol b. lecithin d. glucocerebroside Page 57 Harper’s 26th^ Edition Chapter 7
155. Deficiency of lipoprotein lipase will result in a increased plasma level of which of the following? a. chylomicron remnant c. LDL b. VLDL d. HDL Page 125,126,207-208 Harper’s 26th^ Edition Chapter 15,

156. Which of the following is needed for the transport of long-chain fatty acids from the cytosol to the mitochondrial matrix? a. carnitine c. glutathione b. S-adenosylmethionine d. phosphoadenosine phosphosulfate Page 180-187 Harper’s 26th^ Edition Chapter 22
157. Major enzyme that digest dietary triacylglycerol a. lingual lipase c. lipoprotein lipase b. pancreatic lipase d. hormone sensitive lipase Page 475-476 Harper’s 26th^ Edition Chapter 44
158. In the liver cholesterol is mainly disposed by: a. being exported as HDL b. being exported as VLDL c. being secreted in the bile as free cholesterol d. being converted to bile acids Page 225-227 Harper’s 26th^ Edition Chapter 26
159. Which is the immediate source of energy of ATP synthesis? a. electron transfer to O 2 c. ADP and Pi b. electrochemical gradient d. solar energy Page 96-97 Harper’s 26th^ Edition Chapter 12
160. The link between the catabolic and anabolic reactions in the energy cycle is: a. ATP c. H+ b. O 2 d. NADH Page 82-85 Harper’s 26th^ Edition Chapter 10
161. Which of the following is a function of pyridoxal phosphate? a. prosthetic group of transaminases b. lowers plasma cholesterol c. a coenzyme to many dehydrogenases d. adds hydride ion to the pyridine ring Page 50,491 Harper’s 26th^ Edition Chapter 7,45
162. What is the role of oxygen in cellular respiration? a. source of electrons to be passed along the respiratory chain b. final receptor of electrons in the respiratory chain c. transporter of electrons from cytosol to mitochondrial matrix d. cofactor of ATP synthase Page 92-101 Harper’s 26th^ Edition Chapter 12
163. Which vitamin is solely synthesized by bacteria and is thus absent from all plants? a. Biotin c. Folic acid b. Ascorbic acid d. Riboflavin Page 494-495 Harper’s 26th^ Edition Chapter 45
164. This vitamin is required for the synthesis of neurotransmitters like epinephrine: a. Niacin c. Pyridoxine b. Ascorbic acid d. Riboflavin Page495-496 Harper’s 26th^ Edition Chapter 45

165. Deficiency of this mineral is prevalent among pregnant women living in mountainous areas: a. iron c. copper b. iodine d. magnesium Page 447-449 Harper’s 26th^ Edition Chapter 42
166. Which of the ff. accumulates in carnitine deficiency in humans? A. glycogen **B. odd-numbered fatty acids *** C. triglycerides D. sphingolipids
167. Which regulatory action involves a reversible covalent modification of an enzyme? A. allosteric modulation B. competitive inhibition C. association of apoenzyme with a cofactor **D. phosphorylation of Ser hydroxyl on the enzyme ***
168. The Ping-pong mechanism of enzyme kinetics applies to which of the reactions? A. one-substrate **B. bisubstrate *** C. multiple substrate D. hydrolytic
169. Enzymes hasten the rate of chemical reactions through which of the ff.? A. covalent modification of coenzymes and reactants B. enhancing proximity and local concentration of substrates **C. decreasing the free energy of activation *** D. increasing the over-all free energy change of the reaction
170. What is the role of oxygen in electron transport system? A. accepts electrons from FADH2 **B. the final acceptor of electrons *** C. a mobile electron carrier D. donates electron to water
171. Which of the ff. BEST explains why oxidation of FADH2 produces less ATP than NADH? **A. FADH2 enters ETS via complex II *** B. FADH2 transfers less electrons through ETS than NADH C. Electrons from FADH2 are not transferred to oxygen D. inner mitochondrial membrane is impermeable to FADH2
172. Which of the ff. BEST applies to Isoelectric ph of a protein? A. ph is physiologic **B. net charge is zero *** C. protonation is maximum D. ionization is maximum
173. What kind of a reaction is interconversion of aldose and ketose? A. dehydration B. reduction C. oxidation **D. isomerization ***

174. In the over-all scheme of human metabolism, which organ plays impt role? A. brain **B. liver *** C. muscle D. kidney
175. Which of these enzymes is important in protein digestion? A. ptyalin **B. trypsin *** C. invertase D. pancreatic amylase
176. The beta pleated sheet of a protein is classified as which level of protein? A. primary C. tertiary **B. secondary *** D. super secondary
177. What is the cause for the lactic acidosis that develops in thiamine deficiency? **A. conversion of pyruvate to acetyl-CoA is blocked *** B. conversion of pyruvate to oxaloacetate is blocked C. the transketolase reaction that transfers 3-carbon units is blocked D. the transaldolase reaction has increased activity
178. Which of the ff. statements BEST describes collagen? A. left handed helix B. 2 left handed alpha helices C. double helical structure **D. triple helix ***
179. Which of these BEST explains the role of HCL in the stomach? A. kills H. pylori organisms **B. denatures proteins *** C. ideal ph for amylase action D. stimulates pancreatic juice sec’n
180. Which of the ff. bonds stabilizes the primary structure of a protein? **A. hydrogen *** B. disulfide C. ionic D. peptide
181. Which of the ff. are products of the action of salivary amylase on glycogen? A. sucrose **B. maltose *** C. galactose D. fructose
182. A zwiterion is a molecule that contains which of the following? A. **a cation and anion *** C. polar and non-polar groups B. more than one cation D. more than one anion
183. Which of the ff. is most important source of glucose during early fasting? A. liver triglyceride C. muscle protein B. **hepatic glycogen *** D. muscle glycogen

184. A young infant, who was nourished by synthetic formula, had sugar in blood & urine. This compound gave positive reducing sugar test but negative with glucose oxidase test. Which of the ff. compounds is MOST likely to be present in infant’s blood & urine? A. glucose **C. Sorbitol *** B. fructose D. maltose
185. In normal resting state of humans, muscles will mainly use up energy that is provided by which of the ff.? A. carbohydrates **C. fats *** B. muscle glycogen D. amino acids
186. The anemia that develops in patients on anti-malarial therapy may be due to deficiency of enzymes that belong to which metabolic pathway? A. Embden-Mayerhoff **C. hexose monophosphate *** B. Kreb’s TCA D. Kreb’s-Hanseleit
187. Which of the ff is the primary function of the Pentose Phosphate pathway? A. ATP production B. NADPH generation **C. NADPH generation & production of ribose units *** D. Provision of ribose units for nucleotide/ nucleic acid synthesis
188. Which of the ff, is the major metabolic substrate required by RBC? A. Glycerol C. fructose B. free fatty acids **D. glucose ***
189. Which of the ff. is true of the TATA box? A. binds to anti-codon C. encodes repressor proteins **B. binds RNA polymerase *** D. located in first structural gene
190. SRS-A, the slow reacting substance of anaphylaxis, is composed of which of the ff? A. thromboxanes **C. leukotrienes *** B. prostaglandins D. prostacyclins
191. The regulation of cholesterol synthesis primarily occurs at which enzymatic site? A. 3-hydroxy-3-methylglutaryl CoA synthase B.3-hydroxy-3-methylglutaryl CoA lyase **C.3-hydroxy-3-methylglutaryl CoA reductase *** D.3-methyl-3-hydroxylglutaryl CoA oxidase
192. What is the major source of reducing equivalents used for fatty acid syn? **A. pentose phosphate pathway *** B. Embden-Mayerhoff pathway C. the tricarboxylic acid cycle D. Pyruvate dehydrogenase pathway
193. What is the role of aspirin in the treatment of rheumatoid arthritis? A. inhibits the release of arachidonic acid B. directly neutralizes prostaglandins & thromboxanes **C. inactivates cyclooxygenase *** D. shuts down the synthesis of all eicosanoid

194. Patients suffering from familial defect in Apo B 100 have significantly elevated levels of plasma LDL’s. Which is the major reason for this? **A. inability of LDL to interact with the LDL receptor *** B. inability of LDL to activate lipoprotein lipase C. inability of LDL to activate cholesterol transfer protein D. LDL interaction with LDL receptors fail to stimulate endocytosis
195. What is the pharmacological benefit of the drug – Lovastatin? A. inhibits intestinal absorption of dietary cholesterol B. inhibits hepatic production of VLDL **C. inhibits HMG-CoA reductase *** D. absorbs bile acids, increasing their rate of elimination in the feces
196. In an average adult, which % of body protein is turned over on a daily basis? **A. 1 – 2 % *** C. 5 – 6 B. 3 – 4 % D. 7 – 8 %
197. Which vitamin combines with opsin to form the visual pigment in the eye? **A. A *** C. E B. D D. K
198. Which of the following is the cause of muscle fatigue following vigorous exercise? A. sodium and potassium imbalance B. the utilization of ATP C. accumulation of ADP and PI **D. accumulation of lactate ***
199. Which intermediate of pyrimidine biosynthesis is common to the urea cycle? A. ornithine **C. carbamoyl phosphate *** B. citrulline D. carbamoyl aspartate
200. Which of these is a function of nonsense codons? A. they code for non-essential amino acids B. they are responsible for degeneracy of the genetic code C. they base pair with the anticodons **D. they may be used in the cell as termination signals ***
201. Which phase of protein synthesis does the release of newly synthesized polypeptide from the ribosome take place? A. initiation C. release B. elongation **D. termination ***
202. Which of the ff. directs the polypeptide’s ultimate destination in the cell? A. codons **C. signal peptides *** B. molecular chaperones D. signal recognition particles
203. What is the primary action of methotrexate, a chemotherapeutic agent? **A. displaces cells of folate *** C. inhibits phosphorylation of free bases B. inhibits cellular kinase activity D. inhibits synthesis of nucleotides
204. Which of these is the first reaction in the metabolism of all sugars?