BOARD REVIEW QUESTIONS IN BIOCHEMISTRY 1. What is the ion product of water? A. It is the total number of negatively and positively charged ions in 1 liter of aqueous solution. B. It is the product of the concentrations of hydrogen and hydroxyl ions in an aqueous solution. C. It is the number of ionized molecules of water in 1 mole of pure water. D. It is the sum of all hydrogen and hydroxyl ions in an aqueous solution. Ans. B Ref: Harper’s Biochemistry 24th ed. pp.18-19 MPL: 0.75 2. A very anxious student hyperventilates an hour before the biochemistry board exam. What is the effect of hyperventilation on his Pco2 and blood pH? A. Pco2 decreases and pH increases. B. Pco2 decreases and pH decreases. C. Pco2 increases and pH decreases. D. Pco2 increases and pH increases. Ans. A Ref: Harper’s Biochemistry 24th ed. Pp. 18-19 MPL: 0.25 3. A protein rich in which of the following amino acids will provide the greatest buffering capacity at physiologic pH? A. Valine B. Aspartic acid C. Lysine D. Histidine Ans. D Ref: Harper’s Biochemistry 24th ed. p.26 MPL: 0.75 4. Which of the following laboratory results would best indicate metabolic alkalosis? A. Increased Pco2, increased pH, increased HCO3. B. Normal Pco2, increased pH, decreased HCO3. C. Increased Pco2, increased pH, normal HCO3. D. Decreased Pco2, increased pH, normal HCO3. Ans. A Ref: Harper’s Biochemistry 24th ed. p.304 MPL: 0.75 5. What is the property of water that will contribute the most to its ability to dissolve compounds? A. Very few interactive forces in its structure. B. Hydrogen bond formation between water and long-chain fatty acids. C. Covalent bond formation between salt and water. D. Hydrogen bond formation between water and biochemical molecules. Ans. D Ref: Harper’s Biochemistry 24th ed. p.15-17 MPL: 0.75 6. A child’s developmental progress is noted to stop at 2 years old. The following year, skeletal deformities appear. The child regresses to a vegetative state at 10 years old. Urine examination tests positive for glucosaminoglycans that include most likely which of the following? A. Collagen B. Glycogen C. GABA D. Heparan sulfate Ans. D Ref. Harper’s Biochemistry 24th ed. p. 673 MPL: 0.25 7. A 3-year old child is diagnosed to have Hurler’s syndrome. The diagnosis of Hurler’s syndrome is MOST efficiently made by analyzing the patient’s DNA for: A. A region of DNA that does not encode RNA. B. Alternative forms of the L-Iduronidase gene. C. The entire set of genes in one leukocyte. D. A nucleotide substitution in the L-Iduronidase gene. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 678 MPL: 0.25 8. Which of the following statements regarding a double-helical molecule of DNA is TRUE? A. All hydroxyl groups of pentoses are involved in linkages. B. Bases are perpendicular to the axis. C. Each strand is identical. D. Each strand replicates itself. Ans. B Ref: Harper’s Biochemistry 24th ed. p.386 MPL: 0.75
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9. A human DNA sample is subjected to increasing temperature until its major fraction exhibit optical density changes. A minor fraction of the sample DNA is atypical because it required a higher temperature to denature. This atypical minor fraction of sample DNA must have a higher content of: A. Adenine + Cytosine B. Cytosine + Guanine C. Adenine + Thymine D. Adenine + Guanine Ans. B Ref: Harper’s Biochemistry 24th ed. p. 387-388 MPL: 0.75 10. A newborn baby has a sibling with sickle cell anemia and is at risk for this disease. The appropriate diagnostic test for sickle cell anemia in this baby would include which of the following? A. DNA amplification B. Hemoglobin antibodies C. Red cell counting D. DNA fingerprinting Ans. A Ref: Harper’s Biochemistry 24th ed. p. 468 MPL: 0.25 11. Which of the following would BEST describe polymorphism? A. One phenotype, multiple genotypes B. Non-random allele association C. One locus, multiple abnormal alleles D. One locus, multiple normal alleles Ans. D Ref: Harper’s Biochemistry 24th ed. p. 476 12. What is that process that occurs at the 5-position of Cytidine and is often correlated with gene inactivation? A. Gene conversion B. Sister chromatid exchange C. Gene rearrangement D. DNA methylation Ans. D Ref: Harper’s Biochemistry 24th ed. p.466 MPL: 0.75 13. Restriction Fragment Length Polymorphism (RFLP) analysis can only be used to follow the inheritance of a genetic disease if: A. The disease-causing mutation is at or closely linked to an altered restriction site. B. Proteins of mutated and normal genes migrate differently upon gel electrophoresis. C. Mutations are outside restriction sites so that cleaving still occurs. D. mRNA probes are used in combination with antibodies. Ans. A Ref: Harper’s Biochemistry 24th ed. p. 478 14. DNA polymerases synthesize DNA only in the 5’ to 3’ direction. However, at the replication fork, both parentral strands of DNA are being replicated with the synthesis of new DNA. How is it possible that while one strand is being synthesized in the 5’ to 3’ direction, the other strand appears to be synthesized in the 3’ to 5’ direction? This is best explained by: A. 3’ to 5’ DNA repair enzymes B. 3’ to 5’ DNA polymerase C. Okazaki fragments D. Lack of RNA primer on one of the strands. Ans. C Ref: Harper’s Biochemistry 24th ed. p407 MPL: 0.75 15. The chromosomes of mammalian cells are 20 times as large as those of Escherichia coli. How can replication of mammalian chromosomes be carried out in just a few minutes? A. The higher temperature of mammalian cells allows for an exponentially higher replication rate. B. Hundreds of replication forks work simultaneously on each piece of chromosomal DNA. C. Many RNA polymerases carry out replication simultaneously on chromosomal DNA. D. The presence of histones speeds up the rate of chromosomal DNA replication. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 407 16. Sickle cell anemia is the manifestation of homozygous genes for an abnormal hemoglobin molecule. The mutation in the beta-chain is known to produce a single amino acid change. The most likely mechanism for this mutation is: A. Two base insertion B. Three base deletion C. Nondysjunction D. Point mutation Ans. D Ref: Harper’s Biochemistry 24th ed. p. 734
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17. A culture of bacteria not resistant to Tetracycline develops an infection from a virus that is derived from the lysis of tetracycline-resistant bacteria. Most of the bacterial progeny of the original culture is found to have become resistant to tetracycline. What phenomenon has occurred? A. Conjugation B. Recombination C. Transformation D. Transduction Ans. D Ref: Harper’s Biochemistry 24th ed. p. 471 MPL: 0.75 18. Following ultraviolet damage to DNA in the skin, which of the following is MOST likely to occur? A. A specific nuclease detects damaged areas. B. Purine dimmers are formed. C. Both strands are cleaved. D. Endonuclease removes the damaged strand. Ans. A Ref: Harper’s Biochemistry 24th ed. p. 814 MPL: 0.75 19. Which of the following statements about the genetic code is the MOST accurate? A. Information is stored as sets of dinucleotide repeats called codons. B. The code is degenerate. C. There are 64 codons, all of which code for amino acids. D. Information is stored as sets of trinucleotide repeats called codons. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 433-434 MPL: 0.75 20. Which of the following is provided by the Northern Blot Analysis? A. Detection of specific base pairs. B. Detection of DNA molecules. C. Detection of RNA molecules. D. Detection of proteins. Ans. C Ref: Harper’s Biochemistry 24th ed. p. 472-473 MPL: 1.0 21. In contrast to DNA polymerase, RNA polymerase: A. Fills in the gap between the Okazaki fragments. B. Works only in a 5’ to 3’ direction. C. Edits as it synthesizes. D. Synthesizes RNA primer to initiate DNA synthesis. Ans. D Ref: Harper’s Biochemistry 24th ed. p. 418 MPL: 0.75 22. The removal of introns and subsequent self-splicing of adjacent exons occurs in some portions of primary ribosomal RNA transcripts. The splicing of introns in mRNA precursors is: A. RNA-catalyzed in the absence of protein. B. Carried out by spliceosomes. C. Controlled by RNA polymerase. D. Regulated by RNA helicase. Ans. B Ref: Harper’s Biochemistry 24th ed. p.426 MPL: 0.75 23. What is the function of a promoter site on DNA? A. Transcribes repressor B. Initiates transcription C. Codes for RNA polymerase D. Regulates termination Ans. B Ref: Harper’s Biochemistry 24th ed. p. 420 MPL: 1.0 24. The “sigma factor” found in many bacteria is best described as a: A. Subunit of RNA polymerase responsible for the specificity of the initiation of transcription. B. Subunit of DNA polymerase that allows for the synthesis in both 5’ to 3’ and 3’ to 5’ directions. C. Subunit of the 50S ribosome that catalyzes peptide bond synthesis. D. Subunit of the 30S ribosome to which mRNA binds. Ans. A Ref: Harper’s Biochemistry 24th ed. p. 418 MPL: 0.75
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25. A 23-year old man was rushed to the emergency room with nausea, vomiting, and abdominal pain. Remnants of the death-cap wild mushroom Amanita phalloides were noted upon laboratory examination of his vomitus. A liver biopsy indicates massive hepatic necrosis. Care is supportive. A major toxin of the death cap mushroom inhibits which of the following? A. DNA primase B. RNA nuclease C. DNA ligase D. RNA polymerase Ans. D Ref: Harper’s Biochemistry 24th ed. p. 420 MPL: 0.75 26. The consensus sequence 5’-TATAAAA-3’ found ineukaryotic genes is almost similar to a consensus sequence observed in prokaryotes. The consensus sequence is important as the: A. Only site of binding of RNA polymerase II. B. Promoter site for all RNA polymerases. C. Termination site for RNA polymerase II. D. First site of binding of a transcription factor for RNA polymerase II. Ans. D Ref: Harper’s Biochemistry 24th ed. pp. 421-422 MPL: 0.75 27. The so-called “caps” of RNA molecules: A. Allow tRNA to be processed. B. Occur at the 3’-end of tRNA. C. Are composed of poly A. D. Are unique to eukaryotic mRNA. Ans. D Ref: Harper’s Biochemistry 24th ed. p. 428 MPL: 1.0 28. In bacterial RNA synthesis, what is the function of the “rho” factor? A. It binds catabolite repressor to the promoter region. B. It increases the rate of RNA synthesis. C. It eliminates the binding of RNA polymerase to the promoter. D. It participates in the proper termination of transcription. Ans. D Ref: Harper’s Biochemistry 24th ed. p. 419 MPL: 1.0 29. Which of the following statements correctly describes the nucleolus of a mammalian cell? A. It differs from that found in bacterial cells in that histones are present. B. It may contain hundreds of copies of genes for different types of ribosomal RNAs. C. It synthesizes 5S rRNA. D. It synthesizes all ribosomal RNA primary transcripts. Ans. B Ref; Harper’s Biochemistry 24th ed. p. 428 MPL: 0.75 30. Which of the following statements correctly describes the synthesis of mammalian mRNA? A. Each mRNA often encodes several different proteins. B. Several different genes may produce identical mRNA molecules. C. Mammalian mRNA undergoes minimal modification during its maturation. D. The RNA sequence transcribed from a gene is identical to the mRNA that exits from nucleus to cytoplasm. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 427 MPL: 0.75 31. Certain amino acids are not part of the primary structure of proteins but are modified after translation. In scurvy, which amino acid that is normally part of collagen is not synthesized? A. Hydroxytryptophan B. Hydroxytyrosine C. Hydroxyhistidine D. Hydroxyproline Ans. D Ref: Harper’s Biochemistry 24th ed. pp. 668-669 MPL: 1,0 32. Immunoglobulin G (IgG) molecules can be characterized by which of the following statements? A. They are maintained at a constant level in the serum. B. They contain nucleic acids. C. They contain mostly carbohydrates. D. They can be separated into subunits with a reducing agent and urea. Ans. D Ref: Harper’s Biochemistry 24th ed. p.716 MPL: 1.0
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33. Which of the following proteolytic enzymes is activated by acid hydrolysis of the proenzyme form? A. Trypsin B. Elastase C. Pepsin D. Carboxypeptidase Ans. C Ref: Harper’s Biochemistry 24th ed. p.636 MPL: 1.0 34. Which of the following amino acids is ionizable in proteins? A. Leucine B. Histidine C. Valine D. Alanine Ans. B Ref: Harper’s Biochemistry 24th ed. p. 294 MPL: 0.75 35. The oxygen carrier of muscle is the globular protein myoglobin. Which of the following amino acids is highly likely to be localized within the interior of the molecule? A. Arginine B. Aspartic acid C. Glutamic acid D. Valine Ans. D Ref: Harper’s Biochemistry 24th ed. p.53 MPL: 0.75 36. Which of the following statements concerning immunoglobulins is most accurate? A. IgE is the principal antibody in the serum. B. The heavy chains are similar in each class of immunoglobulin. C. The constant regions of the heavy chains are the same in each class of immunoglobulin. D. IgE is the major immunoglobulin found in external secretions. Ans. C Ref: Harper’s Biochemistry 24th ed. p.718 MPL: 1.0 37. Under normal conditions in the blood, which of the following amino acid residues of albumin is neutral? A. Arginine B. Aspartate C. Glutamine D. Histidine Ans. C Ref: Harper’s Biochemistry 24th ed. p. 294 MPL: 0.75 38. A child develops chronic diarrhea and liver inflammation in early infancy when the mother begins using formula that includes corn syrup. Evaluation of the child demonstrates sensitivity to fructose in the diet. Which of the following glycosides contains fructose and therefore should be avoided when feeding or treating this infant? A. Sucrose B. Oaubain C. Lactose D. Maltose Ans. A Ref: Harper’s Biochemistry 24th ed. p.135 MPL: 0.75 39. Which of the following carbohydrates would be most abundant in a diet of strict vegetarians? A. Amylose B. Lactose C. Cellulose D. Glycogen Ans. C Ref: Harper’s Biochemistry 24th ed. p. 141 MPL: 1.0 40. The major metabolic product under normal circumstances by erythrocytes and by muscle cells during intense exercise is recycled through the liver in the Cori cycle. The metabolite is: A. Oxaloacetate B. Glycerol C. Alanine D. Lactate Ans. D Ref: Harper’s Biochemistry 24th ed. p. 200-201 MPL: 0.75
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41. Chronic alcoholics require more ethanol than do nondrinkers to become intoxicated because of a higher level of a specific enzyme levels, the availability of what other substance is rate-limiting in the clearance of alcohol? A. NADH B. NAD+ C. FADH D. FAD+ Ans. B Ref: Harper’s Biochemistry 24th ed. pp. 601-603 42. Following a fad diet of skimmed milk and yogurt, an adult female patient experiences abdominal distention, nausea, cramping, and pain followed by watery diarrhea. This set of symptoms is observed each time the said meal is consumed. A most likely diagnosis is: A. Steatorrhea B. Lactase deficiency C. Sialidase deficiency D. Lipoprotein deficiency Ans. B Ref: Harper’s Biochemistry 24th ed. p. 645 MPL: 0.1 43. A percentage of Filipino population may flush and feel discomfort after drinking small amounts of ethanol in alcoholic beverages. This reaction is due to genetic variation in an enzyme that metabolizes the liver metabolite of alcohol, which is: A. Methanol B. Acetone C. Acetaldehyde D. Glycerol Ans. C Ref: Harper’s Biochemistry 24th ed. p. 264 44. Which of the following enzymes catalyzes the high-energy phosphorylation of substrates during glycolysis? A. Pyruvate kinase B. Phosphoglycerate kinase C. Triosephosphate isomerase D. Glyceraldehyde-3-phosphate dehydrogenase Ans. D Ref: Harper’s Biochemistry 24th ed. p.176 MPL: 1.0 45. Which of the following enzymes is common to both glycolysis and gluconeogenesis? A. Pyruvate carboxylase B. Hexokinase C. Phosphoglycerate kinase D. Fructose 1,6-bisphosphatase Ans. C Ref: Harper’s Biochemistry 24th ed. p.194 MPL: 0.75 46. During the first week of a diet of 1500 calories per day, the oxidation of glucose via glycolysis in the liver of a normal 59-kg woman is inhibited by the lowering of which of the following? A. Citrate B. ATP C. Ketone bodies D. Fructose-2,6-bisphosphatase Ans. D Ref: Harper’s Biochemistry 24th ed. p.176 47. Familial fructokinase deficiency causes no symptoms because: A. Hexokinase can phosphorylate fructose. B. Most tissues utilize fructose. C. Liver fructose-1-phosphate aldolase is still active. D. Excess fructose spills into the bowel and is eliminated in the feces. Ans. A Ref: Harper’s Biochemistry 24th ed. p. 214 MPL: 0.75 48. A newborn begins vomiting after feeding, becomes severely jaundiced, and has liver disease. Treatment for possible sepsis is initiated, and the urine is found to have reducing substances. A blood screen for galactosemia is positive, and lactose-containing substances are removed from the diet. Lactose is toxic in this case because: A. Excess glucose accumulated in the blood. B. Galactose is converted to the toxic substance galactitol. C. Galactose itself is toxic in even small amounts. D. Glucose metabolism is shut down by excess galactose. Ans. B Ref: Harper’s Biochemistry 24th ed. p. 205
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49. Which of the following enzymes catalyzes phosphorylation with the use of inorganic phosphate? A. Hexokinase B. Phosphofructokinase C. Phosphoglycerate kinase D. Glyceraldehyde-3-phosphate dehydrogenase Ans. D Ref: Harper’s Biochemistry 24th ed. p. 179 MPL: 0.75 50. After a well-rounded breakfast, which of the following would be expected to occur? A. Increased activity of pyruvate carboxylase B. Decreased activity of acetyl CoA carboxylase C. Decreased rate of glycogenesis D. Decreased rate of protein synthesis Ans. C Ref. Harper’s Biochemistry 24th ed. p. 179 MPL: 0.75 51. The ability of hemoglobin to serve as an effective transporter of oxygen and carbon dioxide between lungs and tissue is explained by which of the ff. properties? A. The isolated heme group with ferrous iron binds oxygen much more avidly than carbon dioxide B. The α – and β – globin chains of hemoglobin have very fifferent primary structures than myoglobin C. Hemoglobin utilizes oxidized ferric iron to bind oxygen, in contrats to the ferrous ion myoglobin. D. In contrast to myoglobin, hemoglobin exhibits greater changes in secondary and tertiary structure after oxygen binding Ans. D Ref. Harper’s Biochemistry 24th ed. p. 436 MPL 0.75 52. Contraction of skeletal muscle is initiated by the binding of calcium to: A. Tropomyosin B. Troponin C. Myosin D. Actomyosin Ans B Ref. Harper’s Biochemistry 24th ed. p. 687-688 MPL: 0.75 53. Which of the following statements correctly describes transport of oxygen by hemoglobin? A. Oxygen binds to hemoglobin more avidly than does carbon monoxide. B. The binding of oxygen to hemoglobin causes a valence change in the iron of the heme moiety. C. Each of the four heme moieties binds oxygen independently D. The plot of percentage of oxygen bound versus oxygen pressure is sigmoid in shape Ans. D Ref. Harper’s Biochemistry 24th ed. p. 436 MPL: 0.75 54. Which of the following mutations would produce a severe form of thalassemia? A. Deletion of one α-globin locus B. Deletion of one β-globin locus C. Oxidation of heme groups to produce methemoglobin D. Altered RNA processing at both Ans. D Ref. Harper’s Biochemistry 24th ed. p. 734 MPL 0.75 55. The substitution of valine for glutamate at position 6 on the two β chains in sickle cell hemoglobin causes which of the following? A. Increased electrophoretic mobility at pH 7.0 B. Increased solubility of deoxyhemoglobin C. Decreased polymerization of deoxyhemoglobin D. Unchanged primary structure Ans. A Ref. Harper’s Biochemistry 24th ed. p. 476 MPL 0.75 56. An increased affinity of hemoglobin for oxygen may result from which of the following? A. Initial binding of oxygen to one of the four sites available in each deoxyhemoglobin molecule B. High pH C. High carbon dioxide levels D. High 2,3-bisphosphoglycerate levels within erthrocytes Ans. A Ref. Harper’s Biochemistry 24th ed. p. 436 MPL 0.75
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57. The functions of many enzymes, membrane transporters, and other proteins can be quickly activated or deactivated by phosphorylation of specific amino acid residues catalyzed by enzymes called: A. Cyclases B. Kinases C. Phosphatases D. Proteases Ans B Ref. Harper’s Biochemistry 24th ed. p. 64-65 MPL 0.75 58. The chemotherapeutic drug fluoracil undergoes a series of chemical changes in vivo that results in a complex such that it is bound to both thymidylate synthase and methylene-tetrahydrofolate. The inhibition of deoxythymidylate formation and subsequent blockage of cell division is due to: A. Allosteric inhibition B. Competitive inhibition C. Irreversible inhibition D. Non-covalent inhibition Ans C Ref. Harper’s Biochemistry 24th ed. p. 86-88 MPL 0.75 59. The Vmax of the enzyme is the: A. Reciprocal of the absolute value of the intercept of the curve with the x-axis B. Reciprocal of the absolute value of the intercept of the curve with the y-axis C. Absolute value of the intercept of the curve with the x-axis D. Slope of the curve Ans B Ref. Harper’s Biochemistry 24th ed. p. 75-90 MPL 0.75 60. In the study of enzymes, the sigmoidal plot of substrate concentration versus reaction velocity may indicate: A. Michaelis-Menten Kinetics B. Myoglobin binding oxygen C. Cooperative binding D. Competitive inhibition Ans C Ref. Harper’s Biochemistry 24th ed. p. 75, 90 MPL 1.0 61. A non competitive inhibitor of an enzyme: A. Increases Km with no or little change in Vmax B. Decreases Km and decreases Vmax C. Decreases Vmax D. Increases Vmax Ans C Ref. Harper’s Biochemistry 24th ed. p. 86-88 MPL 0.75 62. Which of the following statements correctly describes allosteric enzymes? A. Effectors may enhance or inhibit substrate binding B. They are not usually controlled by feedback inhibition C. The regulatory site may be catalytic site D. Michaelis-Menten kinetics describe their activity Ans A Ref. Harper’s Biochemistry 24th ed. p. 104-105 MPL 0.75 63. Which of the following enzymes is regulated primarily through allosteric interaction? A. Chymotrypsin B. Pyruvate dehydrogenase C. Glycogen phosphorylase D. Aspartate transcarbamoylase Ans D Ref. Harper’s Biochemistry 24th ed. p. 104-105 MPL 0.75 64. A comatose laboratory technician is rushed into the emergency room. She dies while you are examining her. Her most dramatic symptom is that her body is literally hot to your touch, indicating an extremely high fever. You learn that her lab has been working on metabolic inhibitors and that there is a high likelihood that she accidentally ingested one. Which one of the following is the MOST likely culprit? A. Barbiturates B. Piericidin A C. Dimercaprol D. Dinitrophenol Ans D Ref. Harper’s Biochemistry 24th ed. p. 128 MPL 0.25
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65. Which of the following statements about flavoproteins is TRUE? A. They are not oxidized by coenzymeQ B. They receive electrons from cytochrome P450 in liver mitochondria C. They do not participate in oxidation of NADH dehydrogenises D. They can be associated with sulfur and nonheme iron Ans D Ref. Harper’s Biochemistry 24th ed. p. 117-118 MPL 0.75 66. As electrons are received and passed down the transport chain, the various carriers are first reduced with acceptance of the electron and then oxidized with loss of the electron. A patient poisoned by which of the following compounds has the MOST highly reduced state of the respiratory chain carriers? A. Antimycin A B. Rotenone C. Carbon Monoxide D. Puromycin Ans C Ref. Harper’s Biochemistry 24th ed. p. 128 MPL 0.25 67. Which of the following compounds is a member of the electron transport chain? A. Octanoyl carnitine B. Cytochrome c C. NADH D. Palmitoyl carnitine Ans C Ref. Harper’s Biochemistry 24th ed. p. 128 MPL 0.75 68. All known effects of cyclic AMP in eukaryotic cells result from: A. Activation of the catalytic unit of adenylate cyclase B. Activation of synthetases C. Activation of protein kinase D. Stimulation of calcium release from the endoplasmic reticulum Ans C Ref. Harper’s Biochemistry 24th ed. p. 165 MPL 0.75 69. The connection between oxidative phosphorylation and electron transport is BEST described by: A. Existence of higher pH in the cisternae of the endoplasmic reticulum than in the cytosol. B. Synthesis of ATP as protons into the mitochondrial matrix along a proton gradient that exist across the inner mitochondrial membrane C. Dissociation of electron transport and oxidative phosphorylation D. Absence of ATPase in the inner mitochondrial membrane Ans B Ref. Harper’s Biochemistry 24th ed. p. 127 MPL 0.75 70. If all potential sources of ATP production are taken into account, the net number of ATP molecules formed per molecule of glucose in aerobic glycolysis is: A. 2 B. 6 C. 18 D. 36 Ans B Ref. Harper’s Biochemistry 24th ed. p. 176-184 MPL 0.75 71. Which of the following reactions generates ATP/ A. Glucose 6-phosphate to Fructose 6-phosphate B. Glucose to Glucose 6-Phosphate C. Fructose 6-phosphate to Fructose 1,6-bisphosphate D. Phosphoenolpyruvate Ans D Ref. Harper’s Biochemistry 24th ed. p. 176-184 MPL 0.75 72. which of the following products of triacylglycerol breakdown and subsequent β-oxidation may undergo gluconeogenesis? A. Propionyl CoA B. Acetyl CoA C. All ketone bodies D. Some amino acids Ans A Ref. Harper’s Biochemistry 24th ed. p. 284 MPL 0.75
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73. Which of the following regulates lipolysis in adipocytes? A. Activation of fatty acid synthesis mediated by cAMP B. Activation of triglyceride lipase as a result of hormone-stimulated increases in cAMP production by insulin C. Glyerol phosphorylation to prevent futile esterification of fatty acids D. Activation of cAMP production by insulin Ans D Ref. Harper’s Biochemistry 24th ed. p. 267 74. Inhibition of ATP synthesis during oxidative phosphorylation by oligomycin is thought to be due to: A. Blocking of the proton gradient between NADH-Q reductase & QH 2 B. Blocking of the proton gradient between cytochrome C 1 and cytochrome C C. Dissociation of cytochrome c from mitochondrial membranes D. Inhibition of mitochondrial ATPase Ans D Ref. Harper’s Biochemistry 24th ed. p. 701 MPL 0.75 75. The reactions of the urea cycle occur: A. In the cytosol B. In the mitochondrial matrix C. In the mitochondrial matrix & the cytosol D. Only in lysosomes Ans C Ref. Harper’s Biochemistry 24th ed. p. 301-380 MPL 0.75 76. A newborn becomes progressively lethargic after feeding and increases his respiratory rate. He becomes virtually comatose, responding only to painful stimuli, and exhibits mild respiratory alkalosis. Suspicion of urea cycle disorder is aroused and evaluation of serum amino acids levels is initiated. In the presence of hyperammonemia, production of which of the following amino acids is always increased? A. Glycine B. Arginine C. Proline D. Glutamine Ans D Ref. Harper’s Biochemistry 24th ed. p. 267 MPL 0.75 77. The thyroid hormone thyroxine (T4) is derived from: A. Threonine B. Tyrosine C. Thiamine D. Tryptophan Ans B Ref. Harper’s Biochemistry 24th ed. p. 534-536 MPL 0.75 78. Which of the metabolites below is a precursor of tyrosine? A. L-dihydroxyphenylalanine (DOPA) B. Dopamine C. Norepinephrine D. Phenylalanine Ans D Ref. Harper’s Biochemistry 24th ed. p. 296-297 MPL 0.75 79. Which clinical laboratory observation is suggestive of Hartnup’s disease? A. High fecal levels of tryptophan and indole derivatives B. Elevated plasma tyrosine and methionine levels C. Elevation of glutamine in blood and urine D. Extremely high levels of citrulline in urine Ans A Ref. Harper’s Biochemistry 24th ed. p. 322-325 MPL 0.75 80. The important receive group of glutathione in its role as antioxidant is: A. Serine B. Sulfhydryl C. Tyrosine D. Acetyl CoA Ans B Ref. Harper’s Biochemistry 24th ed. p. 753 MPL 0.75
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81. A newborn develops jaundice that requires laboratory evaluation. Which of the following porphyrin derivatives is conjugated, reacts directly, and is a major component of bile? A. Stercobilin B. Biliverdin C. Bilirubin D. Bilirubin diglucuronide Ans D Ref. Harper’s Biochemistry 24th ed. p. 356 MPL 0.75 82. Which of the following poryphrins give stools their characteristic brown color? A. Biliverdin B. Urobilinogen C. Heme D. Stercobilin Ans D Ref. Harper’s Biochemistry 24th ed. p. 354 83. Chylomicrons, IDL, LDL, and VLDL are all serum lipoproteins. What is the correct ordering of these particles from the lowest to the highest density? A. LDL, IDL, VLDL, Chylomicrons B. Chylomicrons, VLDL, IDL, LDL C. VLDL, IDL, LDL, Chylomicrons D. Chylomicrons, IDL, VLDL, LDL Ans B Ref. Harper’s Biochemistry 24th ed. p. 708 MPL 0.75 84. Ceramide is a precursor to which of the following compounds? A. Phosphatidyl serine B. Sphingomyelin C. Phosphatidyl glycerol D. Phosphatidyl choline Ans B Ref. Harper’s Biochemistry 24th ed. p. 250-252 MPL 0.75 85.
Which of the following steps in cholesterol biosynthesis is thought to be rate-limiting and the locus of metabolic regulation? A. Geranyl pyrophosphate to Farnesyl pyrophosphate B. Squalene to Lanosterol C. Lanosterol to Cholesterol D. 3-hydroxy-3-metylglutaryl CoA to Mevalonic acid Ans B Ref. Harper’s Biochemistry 24th ed. p. 274
86. Humans MOST easily tolerate a lack of which of the following nutrients? A. Protein B. Iodine C. Carbohydrate D. Lipid Ans C Ref.
Harper’s Biochemistry 24th ed. p. 285-286
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87. A deficiency in Vitamin B12 causes: A. Cheilosis B. Beriberi C. Pernicious anemia D. Scurvy Ans D Ref.
Harper’s Biochemistry 24th ed. p. 612-613
88. Which of the following vitaminswould MOST likely become deficient in a person who develops a completely carnivorous lifestyle? A. Thiamine B. Niacin C. Cobalamin D. Vitamin C Ans D Ref. Harper’s Biochemistry 24th ed. p. 612-613 MPL 0.75 89. Fully activated pyruvate carboxylase depends upon the presence of: A. Malate and Niacin B. Acetyl CoA and Biotin C. Acetyl CoA and Thiamine pyrophosphate D. Oxaloacetate Ans B Ref.
Harper’s Biochemistry 24th ed. p. 194
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90. Biotin is involved in which of the following types of reactions? A. Hydroxlations B. Carboxylations C. Decarboxylations D. Dehydrations Ans B Ref. Harper’s Biochemistry 24th ed. p. 606-607 MPL 0.75 91. Which of the following conditions would primarily produce a functional deficiency of Vitamin K? A. Coumadin Therapy B. Broad Spectrum antibiotic C. Premature birth D. Lack of red meat in the diet Ans A Ref. Harper’s Biochemistry 24th ed. p. 727 MPL 0.75 92. A 3 month old boy presents with poor feeding & growth, hypotonia, lactic acidemia, and mild acidosis. The pyruvate to lactate ratio is high, and there is decreased conversion of pyruvate to Acetyl CoA. Which of the following may be considered for therapy? A. Thiamine B. FFA C. Biotin D. Vitamin C Ans A Ref. Harper’s Biochemistry 24th ed. p. 183 MPL 0.25 93. A 2-year old child presents with cough and bronchitis, growth failure, & chronic diarrhea with light-colored foul smelling stools. A deficiency of which vitamin should be considered? A. Vit B6 B. Vit C C. Vit A D. Vit B1 Ans C Ref. Harper’s Biochemistry 24th ed. p. 614-617 MPL 0.25 94. an infant presents with prominent forehead, bowing of the limbs, broad & tender wrists, swelling at the costochondral junction of the ribs, and irritability. Which of the following treatments is the most appropriate for this patient? A. Removal of eggs from diet B. Milk & Sunlight exposure C. Diet of baby food containing liver & ground beef D. Diet of baby food containing leafy vegetables Ans C Ref. Harper’s Biochemistry 24th ed. p. 613 MPL 0.25 95. Allopurinol effectively treats gout but has NO effect on the severe neurological symptoms of Lesch-Nyhan patients because it does not: A. Decrease de Novo purine synthesis B. Decrease de Novo Pyrimidine syntheis C. Inhibit xanthine oxidase D. Increase PRPP levels Ans A Ref. Harper’s Biochemistry 24th ed. p. 378 MPL 0.75 96. Which of the following would rule out hyperuricemia in a ptient? A. Lesch-Nyhan synthesis B. Gout C. Carbonage phosphate deficiency D. Xanthine oxidase hyperactivity Ans C Ref. Harper’s Biochemistry 24th ed. p. 381 MPL 0.75 97. Which of the following contributes nitrogen atom to both purine & pyrimidine rings? A. Aspartate B. Carbonage PO4 C. CO2
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98. What is the end product of fatty acid synthase activity in human? A. Palmitic acid B. Palmetoleic acid C. Linoleic D. Arachidonic acid Ans A Ref. Harper’s Biochemistry 24th ed. p. 216-223 MPL 0.75 99. For every 2 moles of free glycerol released by lipolysis of triglycerides in adipose tissue? A. 1 mole of glucose can be synthesized via gluconeogenesis B. 2 moles of triacylglyceride is released C. 2 moles of FFA is released D. 3 moles of Acyl CoA is produced Ans A Ref. Harper’s Biochemistry 24th ed. p. 267 MPL 0.75 100. A 45 year old man ha s a mild heart attack and is placed on diet and Metastatin therapy. Which of the following will result in this therapy? A. Low blood glucose level B. Low blood LDLs C. High blood cholesterol D. Low oxidation of Fa Ans B Ref. Harper’s Biochemistry 24th ed. p. 281 MPL 0.75
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