apmc biochem2

BLUEPRINT FOR QUESTIONS BIOCHEMISTRY AND HUMAN NUTRITION SUBJECT MATTER

QUESTION NUMBERS

RECALL

COMPRE HENSION

APPLICA TION

Bioenergetic, Biological Oxidation, TCA Cycle, ETC

1 – 10

1, 5, 8, 9, 10

2, 3, 4, 6, 7

Chemistry of Amino Acids and Proteins (Enzymes, Hgb, Ig, and Collagen) Amino Acid Metabolisms

11 – 30

11, 14, 19, 21, 23, 24, 25, 29, 30

17, 18, 22, 26. 27. 28

Chemistry of Carbohydrate & Glycoproteins Carbohydrate and Glycoproteins Metabolisms

31 – 45

35, 37, 40, 41, 42, 43, 44, 45

31, 32, 33, 34, 36, 38, 39

Chemistry of Lipids (including Membrane) and Lipid Metabolism

46 – 60

50, 51, 52, 53, 56, 57, 58

46, 47, 49, 54, 55, 59, 60

48

Chemistry of Nucleotides Metabolism of Nucleotides Chemistry of Nucleic Acid Molecular Genetics

61 – 78

62, 66, 67, 71, 75, 78

61, 63, 64. 65. 68, 69, 72, 73, 74, 76, 77

70

Nutrition (including Digestion and Absorption)

79 – 90

82, 85, 89, 90

79, 80, 81, 84, 86, 87, 88

83

Other Topics

91 – 100

92, 93, 95, 96

91, 94. 97. 98, 100

99

MEAN MPL FOR THE EXAM = 62.49 REFERENCE BOOKS: REFERENCE A = HARPER’S BIOCHEMISTRY 26TH EDITION REFERENCE A = HARPER’S BIOCHEMISTRY 25TH EDITION

12. 13. 15, 16, 20

CEBU INSTITUTE OF MEDICINE BIOCHEMISTRY AND HUMAN NUTRITION DIRECTION; Each question below is followed by four possible answers. Select the one best response and mark the appropriate spaces on the answer sheet provided for. 1. Endergonic process refers to which of the following? A. Can exist independently B. Proceeds spontaneously C. Exemplified by active transport D. Presence of both gain and loss of free energy (Answer: C / Reference A: p. 81 / MPL 60) 2. The mechanism of action of an uncoupling agent is to: A. inhibit the transport of adenosine molecules B. inhibit the third site of ATP formation C. enable AMP to regulate respiration D. allow leakage H+ across membrane (Answer: D / Reference A: p. 97 / MPL 60) 3. The ATP synthase id found in which of the following phosphorylating subunits: A. Fo C. Both Fo and F1 B. F1 D. Neithere Fo nor F1 (Answer: B / Reference A: p. 97 / MPL 90) 4. One of the following is CORRECT as regards citric acid cycle: A. Acetyl CoA is regenerated B. Absence of oxygen cause total inhibition of the cycle C. Two pairs of carbon dioxide are released D. Provides the greatest quantitative source of ATP (Answer: B / Reference A: p. 130-133 / MPL 60) 5. Which of the following respiratory chain complexes DOES NOT support phosphorylation? A. NADH: ubiquinone oxidoreductase B. Succinase: ubiquinone oxidoreductase C. Ubiquinol: ferricytochrome C oxidoreductase D. Ferrocrytochrome C: oxygen oxidoreductase (Answer: B / Reference A: p. 96 / MPL 60) 6. An important feature of the electron transport chain: A. It is an anion pump. B. It provides most of the energy captured in metabolism. C. It is arranged in order of decreasing redox potential. D. It is both aerobic and anaerobic (Answer: B / Reference A: p. 92-93 / MPL 60) 7. An important feature of the TCA cycle: A. One turn of the cycle yields 14 ATPs. B. The process occurs partly in the cytosol and partly in the mitochondrial matrix. C. The cycle can produce ATP through substrate phosphorylation. D. It generates NADPH + H+, FADH2, FMNH2 (Answer: C / Reference: p. 132-133 / MPL 60)

8. Which of the following enzymes protects aerobic organism against oxygen toxicity? A. Catalase C. Homogentisate dioxygenase B. Cytochrome P 450 D. Superoxide dismutase (Answer: D / Reference A: p. 90 / MPL 90) 9. The energy from oxidation of components of respiratory chain is coupled to: A. translocation of protons C. flow of electrons from NAD B. chemical potential difference D. electrical potential difference (Answer: A / Reference A: p. 95 / MPL 90) 10. Carbon monoxide and cyanide poisoning affect the respiratory chain and specifically both inhibit: A. NADH dehydrogenase C. cytochrome oxidase B. ubiquinone oxidoreducatase D. ferricytochrome c oxidoreductase (Answer: C / Reference A: p. 95 / MPL 90) 11. This substituent attached to @ carbon of amino acids distinguishes amino acids from each other: A. Amino group C. Hydrogen atom B. Carboxylic group D. R group (Answer: D / Reference A: p. 18 / MPL 90) 12. Which of the following amino acyl residues are likely to be found in the interior of a globular protein? A. Aspartyl, histidyl, and tyrosinyl residues B. Alanyl, isoleucyl, and methionly residues C. Glutamyl, arginyl and asparaginyl residues D. Cysteinyl, threonyl, and lysyl residues (Answer: B / Reference A: p. 15-16 / MPL 60) 13. Which of the following interactions is possible between distant amino acyl residues in a protein? A. Peptide bond formation between alanine and glutamic residues B. Disulfice bond formation between two cysteine residues C. Hydrophobic interaction between asparagine and histidine residues D. Ionic interaction between tyrosine and glycine residues (Answer: B / Reference A: p. 15-16, 19, 35. / MPL 60) 14. During protein folding when regions of amino acyl residues have similar psi and phi bond angles, the protein is said to assume this structural conformation: A. Primary structure C. Tertiary structure B. Secondary structure D. Quaternary structure (Answer: B / Reference A: p. 31 / MPL 90) 15. The highest protein structural organization assumed by both functional hemoglobin and Ig molecules: A. Primary structure C. Tertiary structure B. Secondary structure D. Quaternary structure (Answer: D / Reference: p. 40, 591 / MPL 60)

16. Which of the following is CORRECT as regards amino acid and/or protein separation? A. In electrophoresis of amino acid mixture, both valine and isoleucine move toward the cathode end. B. In paper chromatography involving tryptophan, leucine, lysine and threonine, the amino acid that travels the farthest distance is lysine. C. In isoelectric focusing of proteins, the protein becomes stationary at pH = its pI and it has no net charge. D. The principle of SDS-PAGE in protein subunits determination is based on number of charge groups in the subunit. (Answer: C / Reference A: p. 24; B: p 33-35 / MPL 33) 17. Which of the following proteins involve in protein folding or organization causes diseases in man and animal? A. Molecular chaperones facilitate appropriate interactions between complementary groups. B. Prolyl cis-trans isomerase catalyzes isomerization between cis and trans configuration of X-Pro peptide bonds. C. Protein disulfide isomerase facilitates `shuffling’ of disulfide bonds. D. PrP facilitates the interconversion of @ helical structure with B pleated sheet. (Answer: D / Reference A: p. 36-37 / MPL 60) 18. The common biochemical pathology seen in Creutzfeldt-Jakob and Alzheimer’s Diseases? A. Improper folding of affected proteins secondary to absence of chaperonins. B. The secondary helical structure of affected proteins are transformed into B sheet. C. The so-called “infective agent” is the mutated apolipoprotein E. D. Aggregation of “infected” proteins forming neurofibrillary tangles. (Answer: B / Reference A: p. 37 / MPL 60) 19. Synthesis of nutritionally nonessential amino acid involves the: A. formation of aspartate from a glycolytic intermediate B. hydroxylation of phenylalanine to form tyrosine C. interconversion of proline and glutamate via tetrahydrofolate. D. transamination of @ketoisovalerate to valine (Answer: B / Reference A: p. 237, 239, 328 / MPL 60) 20. Degradation of which of the following proteins requires ATP and ubiquitin? A. Elastin C. Membrane asialoglycoprotein B. Adenylosuccinase D. PRPP amidotransferase (Answer: D / Reference A: p. 242 / MPL 33) 21. The chief mechanism for the removal @ amino group from amino acids is: A. hydrolytic deamination C. transamination B. reductive deamination D. transamidination (Answer: C / Reference A: p. 243 / MPL 60) 22. In the urea cycle: A. the carbons of aspartate are partially incorporated into arginine B. N-acetylglutamate serves as the allosteric activator of carbamoyl phosphate synthetase I C. arginine is the immediate precursor of citrulline D. energy in the form of 3 moles of GTP is required. (Answer: B / Reference A: p. 246 / MPL 60)

23. The major mechanism of detoxification of ammonia in the brain tissue is the formation of: A. @ ketoglutarate C. succinate B. glutamine D. urea (Answer: B / Reference A: p. 244-245 / MPL 60) 24. Oxidative decarboxylation of which of the following amino acids via a mitochondrial multienzyme complex that is analogous to pyruvate dehydrogenase complex? A. histidine, tryptophan, phenylalanine B. valine, leucine, isoleucine C. threonine, serine, tyrosine D. alanine, glycine, asparagine (Answer: B / Reference A: p. 259 / MPL 60) 25. In amino acid catabolism, which of the following is a CORRECT PAIR as regards clinical disorder and its associated deficient enzyme? A. Absence of @ branched chain keto acid decarboxylase – Richner Hanhart Syndrome B. Ornithine transcarbamoylase deficiency – Hyperammonemia type 1 C. Hydroxyphenylpyruvate hydroxylase deficiency – Classic phenylketonuria D. Lack of homogentisate oxidase – Alkaptonuria (Answer: D / Reference A: p. 247, 255, 259 / MPL 60) 26. Deficiency of B complex vitamins can lead to decreased enzymatic activity because derivative of B complex: A. are allosteric effectors for some enzymes. B. are important component of active sites. C. act as co-enzymes of some enzymes. D. are needed to form ribozymes. (Answer: C / Reference A: p. 50 / MPL 60) 27. Multiple factors affect the rates of enzyme-catalyzed reactions. The effect of pH is to: A. increase the kinetic energy of the reacting molecules. B. mediate the formation of bridges complexes between enzyme and substrate. C. alter the charged state of the enzyme and substrate. D. enhance local concentration (Answer: C / Reference A: p. 64 / MPL 60) 28. Enzymes as biological catalysts speed up chemical reactions because they: A. alter the delta G0 of the overall reaction. B. allow substrate binding and catalysis to occur at the active site. C. lower the activation energy for the formation of transition state. D. enhance the effect of positive modulators. (Answer: C / Reference A: p. 61 / MPL 60) 29. Which of the following CORRECTLY characterizes an Ig molecule? A. Maternal Ig A can readily cross the placenta to give protection to the fetus. B. Specific Ag binding sites are found in the hypervariable regions of Ig M. C. Ig G plays an important role in hypersensitivity reactions to allergens. D. Ig E can activate both the classical and alternate complement systems for bacteriolysis. (Answer: B / Reference: p. 591, 594 / MPL 60) 30. Collagen fibers are stabilized by formation of intra and interchain cross links via: A. S-S bonds and ionic interactions B. peptide bonds and salt bridges C. desmosines D. Schiff bases and aldol condenstion products

(Answer: D / Reference A: p. 38 / MPL 60) 31. Which of the following is TRUE of the stereoisomerisms of monosaccharides? A. Furanose and pyranose exhibit mutarotation via formation of acyclic intermediate. B. The ketose counterpart of fructose is fructulose. C. @ and B anomers are mirror images of each other. D. L iduronic acid is the epimer of D glucuronic acid. (Answer: D / Reference A: p. 102, 104, 543; B: p. 151 / MPL 60) 32. Which of the following is the importance of some derived monosaccharide? A. N-acetyl glucosamine is involved in the conjugation reactions of drug metabolism hepatic ER. B. Phosphorylation of glucose as glucose-6-phosphate traps the hexose for entry into carbohydrate metabolism. C. Deoxyribose is an important component of several plasma glycoproteins. D. L fucose is a component of the disaccharide unit found in keratan sulfate. (Answer: B / Reference: p. 106, 136, 542, 628/ MPL 60) 33. Common characteristic among polysaccharides, starch, glycogen and cellulose: A. All are branched molecules with more branching noted in glycogen. B. @ 1->4 glycosidic linkages connect the monosaccharide units in its linear portion. C. All are homopolysaccharides with glucose as the repeating saccharide units. D. They are all storage energy molecules of animal and plants cells. (Answer: C / Reference A: p. 107, 109 / MPL 60) 34. The most important monosaccharide in man is glucose because: A. it is the important substrate for cellular glycolysis. B. it is a component of the milk sugar, lactose, as well as table sugar, sucrose. C. it is the monosaccharide units of glycogen. D. It exhibits various frms of stereoisomerisms (Answer: A / Reference A: p. 102, 106, 107, 136 / MPL 60) 35. Two common enzymes for glycolysis and gluconeogenesis: A. Hexokinase and Phosphofructokinase B. Glucose-6-phosphatase and Fructose 1,6 bisphosphatase C. Aldolase and glyceraldehyde-3-phosphate dehydrogenase D. Enolase and pyruvate kinase (Answer: C / Reference A: p. 104, 138 / MPL 60) 36. The lactate dehydrogenase reaction is important under anaerobic conditions because A. it produces NADH and through the electron transport chain forms ATP. B. its product lactate is fed and oxidized in the TCA cycle C. it produces molecular oxygen and allow glycolysis to continue. D. it regenerates NAD+ for the glyceraldehye-3-phosphate dehydrogenase reaction (Answer: D / Reference A 139: p. 139 / MPL 33) 37. In starvation, glucagon induces the formation of which of the following enzymes in carbohydrate metabolism? A. Phosphofructokinase-1 B. Pyruvate kinase C. Fructose 1,6 bisphosphatase D. Phosphoenolpyruvate carboxykinase (Answer: D / Reference A: p. 156 / MPL 60)

38. TRUE of glycogenolysis: A. Protein primer glycogenin is vital for liver glycogenolysis B. Phosphorylase requires one mole of inorganic phosphate to cleave the β 1-4 glycosidic bond releasing glucose-1-phosphate. C. The coenzyme of phosphorylase is thiamine pyrophosphate D. The covalently modified phosphorylated phosphorylase is the active enzyme. (Answer: D / Reference A: p. 145, 146, 147, 491 / MPL 60) 39. In glycogenesis, formation of branch point is synthesized: A. by the reaction of UDP-glucose with carbon 6 of a glucose residue of glycogen B. by the action of amylo 1-4  1-6 transglucosidase. C. through the action of second messenger, cAMP D. by the transfer of glucose unit from a nonreducing end of glycogen to carbon 6 of a glucose unit of glycogen (Answer: B / Reference: p. 145 / MPL 60) 40. Galactosemia, an inherited disorder characterized by inability to metabolize galactose, is seen in persons with deficiency of which of the following enzymes? A. UDP Gal pyrophosphorylase C. Phosphoglucomutase B. UDP Gal 4 epimerase D. Lactose synthase (Answer: B / Reference A: p. 172 / MPL 90) 41. Important glycoprotein and enzyme that participate in chemotactic-phagocytic actions of neutrophils: A. Fibronectin and Myeloperoxidase B. Laminin and cytochrome P450 C. Integrins and NADPH oxidase D. Selectin and cytochrome P450 (Answer: C / Reference A: p. 528, 621 / MPL 33) 42. Primaquine-sensitive hemolytic anemia is seen in persons under treatment for malaria because of deficiency of which of the following proteins? A. GLUT 1 transporter B. Glucose-6-phosphate isomerase C. Glyceraldehyde-3-phosphate dehydrogenase D. Glucose-6-phosphate dehydrogenase (Answer: D / Reference A: p. 169, 613 / MPL 60) 43. Which of the following proteoglycans found in the intima of the arterial wall binds plasma low density lipoproteins causing atherosclerotic plaques? A. chondroitin sulfate proteoglycan C. heparan sulfate proteoglycan B. dermatan sulfate proteoglycan D. hyaluronic acid (Answer: B / Reference A: p. 548 / MPL 60) 44. Glycoproteins containing mannose-6-phospate are destined to become: A. mucin in mucous secretion C. lysosomal enzymes B. membrane glycoproteins D. component of ECM (Answer: C / Reference A: p. 524 / MPL 60) 45. Oligosaccharide processing is a characteristic event involved in the synthesis of which glycoprotein? A. GPI-linked glycoproteins C. O-linked glycoproteins B. N –linked glycoproteins D. Collagen and Ig (Answer: B / Reference A: p. 524 / MPL 90)

46. A characteristic feature of ATPase in Na-K pump: A. Catalytic site for ATP is in the extracellular side of the membrane B. Requires cholesterol for its activity C. Catalytic site for Na+ is in the cytoplasmic side D. Conformation remain unchanged (Answer: C / Reference A: p. 427, 428 / MPL 60) 47. The fluidity of membranes can best be described as follows: A. Increased by increasing amount of saturated fatty acids. B. Permeability to water remains unaffected if fluidity is increased. C. Attributed to protein and lipid components. D. Affects all kind of protein functions. (Answer: C / Reference A: p. 422 / MPL 60) 48. Which of the following yields the most ATP? A. Oxidation of the carbon skeleton of leucine by the brain cell. B. Fructolysis of fructose by the sperm cell. C. Glycolysis of glucose by the red blood cell. D. B oxidation of palmitic acid by the cardiac muscle. (Answer: D / Reference A: p. 182 / MPL 60) 49. Polyunsaturated fatty acids should be included in our daily diet because PUFA: A. delay cholesterol excretion. C. up-regulate LDL receptors. B. lower LDL catabolism. D. decrease HDL formation. (Answer: C / Reference B: p. 294 / MPL 60) 50. The main source of NADPH for lipogenesis: A. Glycolysis B. HMP shunt (Answer: B / Reference A: p. 176 / MPL 90)

C. Polyol pathway D. Uronic acid pathway

51. The ATP formation in brown adipose tissue is mainly due to: A. substrate level phosphorylation C. creatine kinase reaction B. oxidative phosphorylation D. adenylyl kinase reaction (Answer: A / Reference A: p. 217 / MPL 90) 52. B oxidation is inhibited in the fed state because malonyl CoA which arises from acetyl CoA inhibits: A. Acetyl CoA carboxylase C. Carnitine palmitoyl transferase I B. Acyl CoA dehydrogenase D. Thiolase (Answer: C / Reference A: p. 187 / MPL 60) 53. Several drugs block the formation of endogenous cholesterol at various stages in its biosynthetic pathway. Which of the following acts by inhibiting HMG CoA reductase? A. choleystyramine resins C. Sitosterol B. lovastatin D. gemfibrozil (Answer: B / Reference A: p. 229 / MPL 90) 54. TRUE of the regulation of cholesterol synthesis: A. Transcription of HMG CoA reductase is repressed by cholesterol B. Insulin inhibits the activity of HMG CoA reductase C. Dietary cholesterol inhibits the synthesis of cholesterol in most cells. D. Mevalonate kinase is regulated via covalent modification. (Answer: A / Reference: p. 220 / MPL 60)

55. Characteristic of reverse cholesterol transport A. Uptake and esterification of cholesterol by HDL 2 forming HDL 3 B. Release of Apo C by HDL 2 associate with small amount of cholesterol. C. Hydrolysis of HDL 2 phospholipid and triaacylglycerol by hepatic lipase D. HDL 2 is smaller and denser than HDL 3 (Answer: C / Reference: p. 210 / MPL 33) 56. The highest proportion of cholesterol is transported in: A. VLDL C. HDL2 B. LDL D. HDL3 (Answer: B / Reference: p. 223 / MPL 90) 57. Which of the following enzymes catalyzes the initial and controlling step in lipogenesis? A. Acetyl CoA carboxylase C. ATP-citrate lyase B. Acyl CoA synthetase D. Fatty acid synthase (Answer: A / Reference A: p. 173 / MPL 90) 58. One of the following is needed in the rate limiting reaction of bile acid synthesis: A. ascorbic acid C. NADH B. Biotin D. succinate (Answer: A / Reference A: p. 226 / MPL 90) 59. The importance of chylomicrons: A. protein rich lipoprotein B. repository of many important apoproteins C. source of triacyglycerol for most cells D. vehicle for transport of dietary lipids in the circulation (Answer: D / Reference A: p. 207 / MPL 60) 60. The biochemical explanation for fatty liver and hyperuricemia in chronic alcoholics: A. Increased mobilization from adipose tissue B. Increased [NADH]/NAD+] ratio C. Increased lactic acid concentration D. Increased esterification of fatty acid in triacylglycerol (Answer: B / Reference: p. 212 / MPL 60) 61. Which of the following structural features characterizes GTP as a biologic transducer of free energy during translation? A. The predominant substituent keto tautomers of guanine B. The acid anhydride bonds between @ and B phosphate groups and B and gamma phosphate groups. C. The β N-glycosidic bond between C’1 and N9. D. The OH groups in ribose moiety (Answer: B / Reference A: p. 286, 287, 289; B: P. 377 / MPL 60) 62. Abnormalities in which of the following enzymes lead to hyperuricemia and Gout? A. Complete absence of HGPRTase B. Relative lack of thioredoxin reductase C. Superactive PRPP synthetase D. Severe deficiency of purine nucleoside phosphorylase Answer: C / Reference A: p. 299, 300 / MPL 60)

63. Which of the following is responsible for the concerted regulation between purine and pyrimidine nucleotide de novo pathways? A. The concerted catalytic activities of the multifunctional catalysts present in both pathways. B. The ability of the products in both pathway to inhibit the formation of PRPP. C. The involvement of common amino acid precursors and carbon dioxide in both pathways. D. The allosteric enzyme control mechanisms in both pathways. (Answer B: A / Reference A: p. 299 / MPL 60) 64. One of the following RNA functions as an enzyme: A. Small cytoplasmic tRNA catalyzes the attachement of amino acid to its cognate tRNA. B. 5.8 s RNA is a peptidyl transferase and catalyzes the formation of peptide bond during elongation step of translation C. Small nuclear RNA has catalytic splicing activity and converts primary transcript to its mature form D. Only B and C are correct (Answer: C / Reference A: p. 311 / MPL 60) 65. Common characteristic between B DNA and mRNA: A. Doublestrandedness with helical grooves B. The nucleotide units are connected via phosphodiester linkages. C. 3’ and 5’ ends of the strand are highly altered and modified. D. Both have adenine, guanine, cytosine and thymine bases. (Answer: B / Reference A: p. 303, 309 / MPL 60) 66. Which of the following DNA sequences is most important for translation? A. Highly repetitive sequence C. Microsatellite repeat sequence B. Moderately repetitive sequence D. Unique sequence (Answer: D / Reference A: p. 320 / MPL 60) 67. The three important properties of DNA polymerases are: A. unwinding, chain initiation and elongation B. chain initiation, elongation and processivity C. elongation, processivity and proofreading D. processivity, proofreading and ligation (Answer: C / Reference A: p. 328 / MPL 90) 68. A common characteristic of replication and transcription: A. Enzyme involved has proof reading activity. B. Both strands serve as template simultaneously. C. Formation of Okazaki fragments or elements D. Adherence to the Watson-Crick base pairing rules (Answer: D / Reference A: p. 328, 341 / MPL 60) 69. TRUE of transcription and translation, but not of replication: A. Both are nuclear events B. Both need initiator protein factors. C. Both require DNA as template D. Both undergo post-synthetic modifications. (Answer: D / Reference A: p. 326, 341, 364, 365, 371 / MPL 60)

70. A segment of DNA 3’ ----- CAGGCCTACCGG ---- 5’ is transcribed into: A. 3’ ----- GUCCGGAUGGCC ---- 5’ B. 3’ ----- CCGGUAGGCCUG ---- 5’ C. 3’ ----- UGAAUUCGUUAA ---- 5’ D. 3’ ----- AAUUGCUUAAGU ---- 5’ (Answer: B / Reference A: p. 303, 341 / MPL 33) 71. The sunlight sensitivity and susceptibility to skin cancer in person with Xerodema pigmentosum is due to the deficient activities of which DNA repair system? A. Base excision-repair systems B. Double-strand break and C. Mismatch repair systems D. Nucleotide excision repair systems (Answer: D / Reference: p. 337 / MPL 90) 72. The importance of TATA box in transcription: A. This box dictates the frequency of transcription B. This box promotes the fidelity of transcription C. Binding of DNA binding protein to this box enhances transcription D. Binding of hormone to this box represses transcription (Answer: C / Reference: p. 345 / MPL 60) 73. A lack of which of the following mammalian nuclear DNA-dependent RNA polymerases blocks translation due to the absence of template for translation? A. RNA polymerase A (I) C. RNA polymerase C (III) B. RNA polymerase B (II) D. RBA polymerase D (IV) (Answer: B / Reference A: p. 343, 365 / MPL 33) 74. An important feature of the genetic code that may protect the codon in the event of a single base substitution: A. Commaless of the genetic code C. Unambiguity of the genetic code B. Degeneracy of the genetic code D. Universality of the genetic code (Answer: B / Reference A: p. 359 / MPL 60) 75. The danger of single base insertion or deletion on the genetic code: A. Frameshift mutation B. Silent mutation C. Partially acceptable missense mutation D. Unacceptable missense mutation (Answer: A / Reference A: p. 363 / MPL 90) 76. Tumor p53 suppresor protein is referred to as the guardian of the genome because it: A. enhances the survival of tissues. B. allows apoptosis to occur on seriously damaged cells C. plays a key role in both G1 and G2 checkpoint control D. arrests the cell cycle at Go phase (Answer: C / Reference A: p. 339: B: p. 800 / MPL 60) 77. Which of the following is TRUE of carcinogenesis? A. Carcinogeneses occurs as a result of genetic mutation secondary to physical and chemical agents only. B. The ultimate carcinogens are usually electrophiles which can readily attack NA C. The most common base involved in mutagenesis is adenine. D. Tumor suppressor gene is transformed to oncogene by insertional mutagenesis (Answer: B / Reference B: p. 787, 788, 793 / MPL 60)

78. A biochemical change found in fast growing tumor cells: A. Increased catabolism of nucleobases and nucleotides B. Inappropriate synthesis of certain growth factors and hormones C. An adult pattern of isozymes D. Markedly decreased glycolysis (Answer: B / Reference B: p. 806 / MPL 60) 79. A TRUE statement as regards digestion of food: A. Pancreatic amylase hydrolyzes @ (1->6) glycosidic bonds in dietary starch and Glycogen. B. Intestinal sucrase-isomaltase hydrolysis yields fructose and maltose molecules. C. Salivary lipase initiates the hydrolysis of dietary triacylglycerol by attacking the sn-2 ester bond. D. Gastric acid activated pepsinogen and enteropeptidase activated trypsinogen act on internal peptide bonds of dietary proteins. (Answer: D / Reference: p. 474, 475, 477 / MPL 60) 80. Which of the following is TRUE of micronutrients absorption? A. Gastric intrinsic factor is required for the absopriton of hematopoeitic B vitamins. B. Impaired fat absorption can lead to calcium and fat soluble vitamin malabsorptions. C. Calbindin is vital for the absorption of macrominerals. D. Absorption of iron is strictly regulated by the concentration of intestinal hemosiderin and plasma transferrin. (Answer: B / Reference A: p. 477, 478 / MPL 33) 81. Which of the following BEST describes the mechanisms for the absorption of monosaccharides in the small intestine? A. Glucose, fructose and galactose are actively absorbed via Na-dependent process. B. SGLT 1 is a sodium-independent facilitative transporter of monosaccharides. C. All monosaccharides exit from the intestinal cells via GLUT 2 facilitative transporters. D. Ligandin and protein Y are operative in the transport of fructose and glucose in high carbohydrate diet. (Answer: C / Reference: p. 475 / MPL 33) 82. The oxidant stress of infection is most likely to trigger the development of: A. cachexia C. marasmus B. kwashiorkor D. 2nd degree malnutrition (Answer: B / Reference: p. 479 / MPL 60) 83. An abnormality in the biliary system of a Filipino is most likely to result in: A. Beri-beri C. Osteomalacia B. Hemorrhagic disorder D. Pellagra (Answer: B / Reference: p. 482 / MPL 33) 84. The importance of sunlight to vitamin D/calcium homeostasis: A. It is the richest source of vitamin D. E. Ultraviolet rays are important for the activation of vitamin D to its functional active form. F. Sunlight is required for the resorption of bone to release calcium in instances of hypocalcemia. G. It participates in photolysis of provitamin D in skin to previtamin D. (Answer: D / Reference A: p. 484 / MPL 60)

85. Inadequate intake of which vitamins/minerals in the maternal diet may result in spina bifida in the newborn: A. Calcium C. Folic acid B. Iron D. Vitamin K (Answer: C / Reference: p. 494 / MPL 90) 86. One of the following is CORRECT of ascorbic acid: A. It is a 6-carbon compound closely related to galactose B. It is a reducing agent and oxygen radical quencher. C. Megadosing of vitamin C has curative effect against common colds. D. Its deficiency state is attributed to deficient elastin formation.. (Answer: B / Reference A: p. 495, 496 / MPL 60) 87. Individual suffereing from carcinoid syndrome will also develop pellagra because of: A. overproduction of 5-hydroxytryptamine B. defective intestinal transport mechanism for tryptophan C. lack of enzyme involved in formation of niacin from tryptophan D. end organ resistance to niacin cellular uptake. (Answer: A / Reference A: p. 490 / MPL 60) 88. Inhibitors of folate metabolism provide cancer chemotherapy and antibacterial and antimalarial drugs because folic acid as tetrahydrofolate participates: A. in the transamination and decarboxylation of amino acids. B. as a one carbon group carrier in purine nucleotide de novo pathway. C. in the interconversion of serine to glycine D. in the methylation of dUMP to TMP. (Answer: D / Reference A: p. 493, 494 / MPL 33) 89. Which vitamin and mineral is involved in blood coagulation? A. Calcitriol and magnesium C. Retinoic acid and potassium B. Menaquinone and calcium D. @ Tocopherol and sodium (Answer: B / Reference A: p. 486, 600 / MPL 90) 90. Hyperhomocysteinemia, a risk factor for cardiovascular disease, is fairly common in the elderly because of inadequate intake or under utilization of: A. B1 and B3 C. B5 and B7 B. B2 and B5 D. B9 and B12 (Answer: D / Reference A: p. 492 / MPL 60) 91. Which of the following best describes the plasma proteins? A. They are principally derived from the diet. B. Almost all plasma proteins are simple proteins like albumin. C. Their half-lives are unaltered by certain diseases. D. Many plasma proteins exhibit polymorphism. (Answer: D / Reference A: p. 582 / MPL 60) 92. Which of the following pathways is the source of fuel for the red blood cells? A. β oxidation of fatty acids C. Transamination of glycine B. Glycolysis of glucose D. Ketone bodies degradation (Answer: B / Reference A: p. 612 / MPL 90) 93. Which of the following neutrophilic enzymes catalyzes the formation of chlorinated oxidants to kill bacteria? A. Lysozyme C. NADH oxidase B. Myeloperoxidase

D. Superoxide dismutase

(Answer: B / Reference A: p. 623 / MPL 90) 94. In xenobiotic metabolism, drug-drug interaction sometimes occurs because the enzyme cytochrome P450 system possesses this characteristic: A. Most versatile biocatalyst C. Many are inducible B. Broad substrate specificity D. Some exhibit polymorphism (Answer: C / Reference A: p. 627-628 / MPL 60) 95. Which of the following xenobiotic phase II conjugating substrate is also involved in transport of certain amino acids into the cells? A. Adenosine 3’ phosho 5’ phosphosulfate C. Glutathione B. S-adenosylmethionine D. UDP-glucuronic acid (Answer: C / Reference A: p. 629 / MPL 90) 96. The rate limiting enzyme for catecholamine synthesis is: A. Catechol-O-methyl transferase C. Monoamine Oxidase B. Dopamine hydroxylase D. Tyrosine Hydroxylase (Answer: D / Reference A: p. 446 / MPL 90) 97. TRUE of iodide metabolism: A. Thyroperoxidase requires hydrogen peroxide as oxidizing agent B. Oxidized tyrosine reacts with iodide in thyroglobulin C. Concentration of iodide is mainly by diffusion D. Even with iodination, iodine can still readily leave the thyroid tissue. (Answer: A / Reference A: p. 449 / MPL 60) 98. Which of the following characterizes the formation of heme in hemoproteins? A. All the atoms of the heme moiety are derived from glycine and succinyl CoA. B. The final step involves the incorporation of ferric ion. C. The key regulatory enzyme is ALA dehydratase. D. Tetrahydrofolate participates in the first and second reactions. (Answer: A / Reference A: p. 270-271 / MPL 33) 99. What is the type of hyperbilirubinemia seen in a 35 y.o. woman in hemolytic crisis? A. Cholestatic jaundice C. Kernicterus B. Direct-reacting hyperbilirubinemia D. Retention hyperbilirubinemia (Answer: D / Reference A: p. 282 / MPL 60) 100. One of the laboratory findings revealed an increased urine urobilinogen. What is responsible for this laboratory result? A. Increased activity of the renal B glucuronidase activity. B. Increased hydrophilic characteristic of the direct-reacting bilirubin. C. Increased enterohepatic urobilinogen cycle D. Increased glucuronosyltransferase activity (Answer: C / Reference A: p. 281 / MPL 33)

93. True of the cytochrome P450 systems, EXCEPT: A. Catalyze reactions involving introduction of one atom of oxygen into the substrate and one into water. B. Exhibit broad substrates specificity C. In some cases, their products are mutagenic and carcinogenic D. All of the above

87. One of the following is INCORRECT as regards the importance of vitamin on the nervous tissues: A. Vitamin C acts as cofactor in the formation of catecholamines. B. Thiamine triphosphate acts as phosphate donor for phosphorylation of the neural membrane sodium transport channels. C. Cobalamine acts as carrier of one-carbon group in the formation of gangliosides. D. Pyridoxal phosphate plays a role in the synthesis of sphingolipids necessary for myelin formation. 89. What is the type of hyperbilirubinemia seen in a 35 y.o. woman with sickle cell disease who had hemolytic crisis? A. Cholestatic jaundice C. Kernicterus B. Direct-reacting hyperbilirubinemia D. Retention hyperbilirubinemia 90. The cause of jaundice in the above patient: A. Decreased activity of hepatic UDP-glucuronosyl transferase B. Decreased albumin binding to bilirubin C. Decreased hepatic content of MOAT proteins. D. None of the above 91. One of the laboratory findings revealed an increased urine urobilinogen. What is responsible for this laboratory result? A. Increased activity of the renal B glucuronidase activity. B. The hydrophilic characterisitic of the direct-reacting bilirubin. C. Increaed enterohepatic urobilinogen cycle D. All of the above 92. Which of the following xenobiotic phase II conjugating substrate is also involved in transport of certain amino acids into the cells? A. Adenosine 3’ phosho 5’ phosphosulfate B. Glutathione C. S-adenosylmethionine D. UDP-glucuronic acid 93. True of the cytochrome P450 systems, EXCEPT: A. Catalyze reactions involving introduction of one atom of oxygen into the substrate and one into water. B. Exhibit broad substrates specificity C. In some cases, their products are mutagenic and carcinogenic D. All of the above 94. One of the following enzymes DOES NOT occupy a central position in amino acid synthesis: A. Amino oxidases C. Glu dehydrogenase B. Aminotransferases D. Gln synthetase

95. One of the following best describes the biosynthesis of nutritionally nonessential amino acids: A. The coenzymes of biotin and cobalamin are involved in the pathways. B. Nutritionally nonessential amino acids have short biosynthetic pathways. C. Intermediates of glycogenlytic pathway serve as substrates. D. Ammonia serves as the amido group for the formation of glutamine and asparagine. 96. Which of the following amino acids can be synthesized from choline, glyoxylate or serine? A. Alanine C. Glycine B. Cysteine D. Proline 97. Arginine is considered as a nutritionally semi-essential amino acid because: A. it is derived from an essential amino acid. B. it is synthesized at rates inadequate to support growth in children. C. it is not commonly found in food. D. Its intestinal transport system is not as efficient as the other amino acids. 98. Alcoholics are expected to develop any of the following, EXCEPT: A. Fatty liver – cirrhosis C. Menkes’ syndrome B. Hyperuricemia D. Wernicke Korsakoff’s syndrome 99. The biochemical reason for the increased deposition of triacylglycerol in hepatic tissues of alcoholics: A. Increased mobilization of fat from adipose tissues B. Increased hydrolysis of lipoprotein triacylglycerol by lipoprotein lipase C. Increased NADH/NAD ratio D. A and C only 100. A metabolic block in the production of plasma VLDL resulting to fatty liver is seen in one of the following conditions: A. Alcoholism C. Starvation B. Chloroform poisoning D. Uncontrolled diabetes mellitus 18. A common sugar in N-linked glycoproteins: A. Fucose B. Galactose

C. Glucose D. Mannose

60. Which of the ff. is used to join the two molecules at the expense of high energy phosphate bond of ATP? A. Isomerases C. Lyases B. Ligases D. Transferases 61. Characteristic feature of enzyme as a catalyst: A. Raises the energy barrier of a reaction B. Provides alternate transition state C. Affects overall free-energy change for reaction D. Involves transition states of high energy levels 62. Changes in the optimal pH value affect acidity of an enzyme by: A. altering the conformation of catalytic site B. a change in the allosteric site

C. exceeding the energy barrier D. increasing the reaction rate 63. Coenzymes are described as: A. not freely diffusible B. ultimate acceptor of functional groups C. water soluble vitamine derivatives D. responsible for the opposite effect of enzymes 64. Regulation of enzyme activity can be achieved through any one of the following, EXCEPT: A. Requirement of ATP in all enzyme regulation B. Compartmentalization of specific metabolic pathways C. Feedback regulation of a step D. Covalent modification of enzyme 65. Effects of substrate concentration of enzyme-catalyzed reaction are any one of the following, EXCEPT: A. If substrate concentration = km, the initial velocty is half maximal B. If substrate concentration exceeds km, the reaction is unaffected by more increase in substrate concentration C. If substrate concentration is below km, initial reaction velocity is directly proportionate to substrate D. If substrate concentration = km and enzyme concentration the initial velocity is maximal 66. In competitive inhibition of enzyme, one of the following occurs: A. Formation of EIS complex B. Both inhibitor and substrate bind at allosteric site A. Increase in reaction rate when adding more substrate & at fixed inhibitor concentration D. Chemical modification of amino acid residue involved in catalysis 67. A low Km value of an enzyme means: A. low affinity of enzyme to the substrate B. low steady state level of substrate concentration C. high tendency of the substrate and enzyme to dissociate D. low rate of reaction 68. Covalent modification of enzymes through phosphorylation is NOT possible with one of the following: A. phenylalanine C. threonine B. serine D. tyrosine 46.

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