Embed Size (px)
Citation preview
BIOCHEMISTRY NATIONAL BOARD EXAM REVIEW
Larry D. BarnesDepartment of Biochemistry
University of Texas Health Science Center at San Antonio
June, 2004Addendum, June 2005 (pg. 35)
The following questions (1-243) are from nine National Dental Board Examinations in Biochemistry-Physiology from 1978-1998. 1998 is the latest board exam released by the American Dental Association. This compilation of questions is intended to show the format, the subject areas generally covered, and the general level of knowledge required. Answers with some commentary are given beginning on page 29. The addenum begins on page 35 followed by answers.
BASIC CHEMISTRY1. Which of the following characterizes exergonic
reactions?
A. Decreased entropyB. Increased enthalpyC. Decreased enthalpyD. Negative free energy changeE. Positive free energy change
2. What thermodynamic parameter is a measure of randomness or disorder in a system?
A. EntropyB. EnthalpyC. Free energyD. Potential energyE. Activation energy
3. Atoms are isotopes of each other only if
A. their nuclei contain the same number of neutrons.
B. their atomic numbers are the same, but their mass numbers differ.
C. their mass numbers are the same, but their atomic numbers differ.
D. one is a beta emitter, but the other is an alpha emitter.
4. Which of the following substances is LEAST polar?
A. EthanolB. CholesterolC. Palmitic acidD. Glycocholic acid
5. Which of the following characterizes an asymmetric carbon?
A. A carbon atom with four identical groups attached to it.
B. A carbon atom with four different groups attached to it.
C. A carbon with at least one carboxyl and one amino group attached to it.
D. A carbon atom that has two heavy groups on one side and two light groups on the other.
6. Which of the following compounds does NOT contain a high-energy bond?
A. ATPB. Acetyl CoAC. UDP-glucoseD. Glucose-6-phosphateE. Phosphoenolypyruvate
7. Which of the following solutions has an osmotic pressure different from all the others?
A. 1 M glucoseB. 1 M sodium chlorideC. 1 M potassium nitrateD. 1 N lithium iodideE. 1 N hydrochloric acid
1
BUFFERS and pH
8. The Henderson-Hasselbach equations shows that
A. dilution of a buffer increases its pH.B. pH = pka when an acid is 0.1 NC. pH = pka when an acid is half neutralized.D. pH is independent of the dissociation
constant of the acid
9. Which of the following represents the pH of a solution that has 10-5 M concentration of OH-
ion?
A. 5B. 7C. 9D. Determine only if the pKa is known.E. Determinable only if the base composition is
known.
10. If the pH becomes lower than the isoelectric point of a protein, then how will the protein respond in an electrophoretic system? It will
A. become denatured.B. migrate to the negative pole.C. migrate to the positive pole.D. remain stationary and unchanged.E. separate into its different monomeric forms.
11. A physiologic buffer functions to
A. regulate the partial pressure of venous carbon dioxide.
B. carry fixed acid from the site of its elimination to the site of its production.
C. transport carbon dioxide from the site of its production to the site of its elimination.
D. minimize the increase in hydrogen ion concentration that accompanies cellular acid production.
E. maximize the decrease in hydrogen ion concentration that accompanies alkali formation.
12. All of the following function in buffer systems in the blood EXCEPT
A. NaCl.B. H2C03.C. NaHCO3.D. Na2HPO4.E. NaH2PO4.
13. The buffer system most important in maintaining the physiological pH of plasma is
A. protein/proteinateB. acetic acid/acetateC. carbonic acid/bicarbonateD. phosphoric acid/phosphateE. hydroxybutyric acid/hydroxybutyrate
BICARBONATE/CO2
14. Neutralization of acids by saliva results mainly from which of the following salivary contents?
A. MucinB. AmmoniaC. CarbonateD. BicarbonateE. Amino acids
15. MOST of the CO2 in blood is combined as
A. H2C03.
B. HCO-3.
C. CH3 –COOH.D. carbonic acidE. carbaminohemoglobin.
2
BICARBONATE/CO2 (Continued)
16. The bicarbonate buffer system of the blood is very efficient because
A. bicarbonate is rapidly excreted by the kidneys.
B. bicarbonate is able to be stored in the tissue.
C. carbon dioxide is able to combine with hemoglobin
D. carbon dioxide forms a stable combination with base.
E. carbon dioxide is rapidly eliminated through the lungs.
17. The normal blood bicarbonate-carbonic acid ratio is 20:1. A patient with a 10:1 ratio is in
A. compensated alkalosis.B. compensated acidosis.C. uncompensated alkalosis.D. uncompensated acidosis.E. none of the above. This patient’s ratio is
within normal limits.
18. Absence of which of the following blood enzymes drastically reduces blood CO2 carrying capacity?
A. Carbonic anhydraseB. Alkaline phosphataseC. Pyruvate carboxykinaseD. Histidine decarboxylaseE. Serum glutamic-oxaloacetate transaminase
PROTEINS
19. Removal of a molecule of water between the carboxyl group of one amino acid and the amino group of a second amino acid results in formation of a
A. zwitterion.B. polypeptide.C. peptide bond.D. hydrogen bond.E. glycosidic bond.
20. Which of the following BEST explains why proteins are able to buffer physiologic solutions over a wide range of pH?
A. They are macromolecules of high molecular weight.
B. They contain many functional groups with differing pKs.
C. They have unique tertiary structures that sequester hydrogen ions.
D. They have peptide bonds that are resistant to hydrolysis.
21. Denaturation usually destroys all of the following bonds in protein EXCEPT
A. hydrogen bonds.B. covalent bonds.C. hydrophobic bonds.D. electrostatic bonds.
22. Which of the following is the best method for determining the three-dimensional structure of protein?
A. DialysisB. ElectrophoresisC. X-ray diffractionD. UltracentrifugationE. None of these
3
PROTEINS (Continued)
23. The amino acid that contributes to the tertiary structure of a protein by causing a bend when it occurs in the primary sequence is
A. leucine.B. alanine.C. proline.D. tyrosine.E. aspartic acid.
24. A mucin is which of the following types of proteins?
A. Simple proteinB. PhosphoproteinC. Chromoprotein.D. Nucleoprotein.E. Glycoprotein.
25. How will a protein respond in an electrophoretic system, should the pH become lower than the isoelectric point of the protein?
A. It will become denaturated.B. It will migrate to the negative pole.C. It will migrate to the positive pole.D. It will remain stationary and unchanged.E. It will separate into its different monomeric
forms.
ENZYMES
26. Which of the following is true regarding enzymes?
A. Are not reusableB. Are needed in large amountsC. Catalyze endergonic reactions onlyD. Increase the energy of activation of the
reactionE. Decrease the energy of activation of the
reaction
27. The optimum pH for an enzyme is the
A. isoelectric point of the enzyme.B. pH of most rapid reaction rate.C. pH at which the enzyme is most soluble.D. pH of most rapid denaturation of the
enzyme
28. The Km value of an enzyme is numerically equal to
A. half the maximum velocity expressed in moles/liter.
B. velocity of a reaction divided by substrate concentration.
C. substrate concentration in moles/liter necessary to achieve half the maximum velocity of a reaction.
D. maximum velocity divided by half the substrate concentration in moles necessary to achieve maximum velocity.
29. In the relationship between the concentrations of substrate and the rate of an enzyme catalyzed reaction, the existence of a limited value (Vmax) of the reaction rate is due primarily to the
A. exhaustion of the substrate supply.B. saturation of the enzyme with substrate.C. inhibition of the enzyme by the reaction
products.D. denaturation of the enzyme at higher
substrate concentrations.E. balance between the increase in reaction
rate with increasing substrate concentrations and accelerated destruction of the enzyme at higher substrate concentrations.
4
ENZYMES (Continued)
30. If the presence of a specific compound, C, increases the Km for an enzyme-substrate reaction, which of the following would be true about that enzyme?
A. C would be a competitive inhibitor of the enzyme.
B. C would be a noncompetitive inhibitor of the enzyme.
C. The velocity vs. [S] plot for the enzyme would be the same with or without C.
D. With C present, the enzyme would convert substrate to product faster.
E. With C present, it would take less substrate to drive the reaction to half-maximum velocity than without C.
31. Protein kinase regulate the activities of key enzymes through which of the following?
A. OxidationB. HydrolysisC. AcetylationD. PhosphorylationE. Dephosphorylation
32. ATP inhibits phosphofructokinase even though ATP also is a substrate for the enzyme. Which of the following types of inhibition BEST explains this phenomenon?
A. AllostericB. CompetitiveC. IrreversibleD. UncompetitiveE. Noncompetitive
33. Enzymes for electron transport reactions are most active and concentrated in which of the following structures of the animal cell?
A. NucleiB. LysosomesC. MicrosomesD. MitochondriaE. All of the above
34. Sodium fluoride inhibits glycolysis by affecting
A. amylaseB. enolaseC. phosphataseD. phosphorylase
35. Which of the following enzymes converts trypsinogen to trypsin?
A. EnterokinaseB. PeptidaseC. SecretinD. Pepsin
36. Two enzymes that have been postulated to play very important roles in calcification are
A. enolase and phosphorylase.B. alkaline phosphatase and catalase.C. pyrophosphatase and carbonic anhydrase.D. pyrophosphatase and alkaline
phosphatase.E. carbonic anhydrase and alkaline
phosphatase.
37. Which of the following enzymes is essentially absent from normal mammalian muscle?
A. GlucokinaseB. PhosphorylaseC. Glucose-6-phosphataseD. Glucose-6-phosphate isomeraseE. Glucose-6-phosphate dehydrogenase
5
ENZYMES (Continued)
38. Dental plaque arises primarily as a result of enzymatic reactions using which of the following?
A. Sucrose and lipidB. Sucrose and salivaC. Glucose and salivaD. Glucose and protein
39. Which of the following liver enzymes, absent from other tissues, gives the liver an advantage over other cells in taking up glucose after a meal?
A. GlucokinaseB. AldolaseC. HexokinaseD. EnolaseE. Glucose-6-phosphatase
COLLAGEN
40. The most abundant protein (by weight) in which the human body is
A. elastin.B. keratin.C. albumin.D. collagen.E. chondroitin.
41. Alpha-ketoglutarate, oxygen, and ascorbic acid are essential for which of the following processes?
A. Incorporation of prolineB. Hydroxylation of prolineC. Gamma-carboxylation of prolineD. Oxidative deamination of lysineE. Activation of procollagen peptidase
42. Which of the following statements concerning collagen is INCORRECT?
A. Collagen has a trihelical structure.B. The molecular weight of collagen is above
100,000C. Hydroxyproline is incorporated into the
molecule by tRNA.D. Destruction of collagen can be caused by
collagenases.E. Collagen contains both hydroxyproline and
hydroxylysine residues.
43. Hydroxylation of proline and lysine during collagen biosynthesis occurs
A. after translation.B. in the mitochondrial matrix.C. before formation of their respective amino
acyl-tRNA’s.D. while proline or lysine is bound to the
peptidyl (P) site on the ribosome.
44. The major protein produced by the odontoblast and contained in the organic matrix of dentin is
A. chitin.B. keratin.C. elastin.D. collagen.E. cellulose.
45. Which of the following do elastin and collagen have in common?
A. Easily stretchedB. Absence of prolineC. Disulfide crosslinkingD. Triple helix structureE. About one-third glycine
6
HEMOGLOBIN
46. The physiologic importance of hemoglobin lies in its ability to combine
A. irreversibly with oxygen and CO2.B. reversibly with oxygen at the ferric heme
prosthetic group.C. irreversibly with oxygen at the ferrous heme
prosthetic group.D. reversibly with oxygen at the ferrous heme
prosthetic group.E. None of the above
47. Which of the following is NOT a part of the hemoglobin molecule?
A. IronB. ProteinC. MagnesiumD. HistidineE. Pyrrole ring
48. Assuming that P50 = 26 torrs, under conditions where pO2 = 30 torrs, the average number of O2
molecules bound per hemoglobin molecule is closest to
A. 0.5.B. less than 1.C. almost 2.D. greater than 2.E. greater than 3.
49. The affinity of hemoglobin for oxygen diminishes as which of the following is decreased?
A. pHB. CO2
C. TemperatureD. Hydrogen ion concentrationE. 2, 3 bisphosphoglyceric acid (BPG)
50. The consequence of appreciable conversion of hemoglobin to methemoglobin is
A. a significant increase in carbon dioxide combining power.
B. a significant decrease in carbon dioxide combining power.
C. no effect on the ability of blood to pick up oxygen.
D. a noticeable increase in the ability of blood to pick up oxygen.
E. a noticeable decrease in the ability of blood to transport oxygen.
51. Compared with hemoglobin A, the substitution of a valine for a glutamic acid residue in hemoglobin S results from
A. a genetic mutationB. irradiation of hemoglobin A.C. proteolytic action in the liver.D. exposure to low oxygen tension.
7
PROTEIN SYNTHESIS
52. The process by which genetic information flows from RNA to protein is
A. mutation.B. replication.C. translation.D. transcription.
53. Which of the following enzymes or processes ensures that the correct amino acid is incorporated for a particular codon during protein synthesis?
A. Amino Acyl-tRNA synthetaseB. Ribosomal protein synthesisC. Post-transcription splicingD. RNA synthetaseE. Helicase
54. Polyuridylic acid in a cell-free system capable of protein synthesis results in production of polyphenylalanine. In this system, polyuridylic acid functions as
A. DNA.B. transfer RNA.C. messenger RNA.D. ribosomal RNA.E. mitochondrial RNA.
55. The termination of synthesis of a polypeptide is believed to involve
A. nonsense codons.B. anticodon-codon interaction.C. tRNA which cannot bind amino acids.D. hydrolysis of messenger RNA.E. none of the above.
56. In prokaryotic protein synthesis, the elongation factor G serves to
A. form the initiation complex.B. facilitate the binding of Fmet tRNA.C. translocate the growing peptide chain and
to move the ribosome along the mRNA.D. prevent the larger ribosomal subunits from
binding with those that are smaller.
57. Streptomycin is an antibiotic which inhibits the process of
A. translation in eukaryotes.B. translation in prokaryotes.C. transcription in eukaryotes.D. transcription in prokaryotes.E. DNA replication in prokaryotes.
58. Each of the following represents an amino acid found in proteins and used directly in the reactions of protein synthesis EXCEPT one. Which one is this EXCEPTION?
A. ProlineB. ArginineC. TryptophanD. AsparagineE. Hydroxylysine
CARBOHYDRATES
59. Hydrolysis of sucrose by the enzyme sucrase yields
A. glucose only.B. glucose and maltose.C. glucose and fructose.D. glucose and galactose.E. fructose and maltose.
60. The arrangement of sugars into D- and L- configurations is based upon their resemblance to D- and L-
A. glycine.B. glucose.C. fructose.D. glyceraldehyde.E. None of the above
8
CARBOHYDRATES (Continued)
61. Which of the following is NOT a monosaccharide?
A. AmyloseB. GlucoseC. FructoseD. GlyceraldehydeE. Glucuronic acid
62. Some carbohydrates convert Cu2+ ions to Cu+
ions. This property is related to their ability to act as
A. a reducing agent.B. an oxidizing agent.C. both a reducing agent and an oxidizing
agent.D. neither a reducing agent nor an oxidizing
agent.
63. What linkages occur in glycogen at branch points between glucose units?
A. Aplpha-1,4B. Alpha-1,6C. Beta-1,3D. Beta-1,4E. Beta-1,6
64. How many anomeric carbons are present in a fructose molecule?
A. 0B. 1C. 2D. 5E. 6
65. Carbohydrate is stored in the body principally as
A. glucose.B. maltose.C. sucrose.D. glycogen.E. glycosaminoglycans.
66. Which of the following molecule features contributes to the water-binding properties of proteoglycans?
A. The carboxyl groups acting as buffersB. Central hyaluronate (a helix) trapping water
withinC. The space between the core proteins and
the hyaluronate being highly charged.D. The large number of alcohol groups on the
polysaccharide chaining H-bond to water.E. The large number of serine and theronine
residues in the core protein offering H-bonding sites.
67. Which of the following functions as part of the extracellular matrix?
A. MucinB. HeparinC. CollaginaseD. Chondroitin sulfateE. Dolichol phosphate
68. Each of the following is a glycosaminoglycan EXCEPT one. Which one is this EXCEPTION?
A. Chondroitin sulfateB. Dermatan sulfateC. Hyaluronic acidD. Heparan sulfateE. Keratin
69. Glycosaminoglycans function as important structural components of
A. glycogen.B. nucleic acids.C. hyaluronidase.D. connective tissue.
70. The carbohydrate in highest concentration in resting muscle is
A. glucose.B. lactose.C. sucrose.D. glycogen.E. inositol.
9
CARBOHYDRATES (Continued)
71. The most biologically important physiochemical property of connective tissue which is regulated by its mucopolysaccharide molecules is
A. viscosity.B. buffering capacity.C. solubility in dilute acides.D. supersaturation with calcium ions.
NUCLEIC ACIDS
72. Which of the following is a pyrimidine base that is present in RNA but is NOT present in DNA?
A. UracilB. GuanineC. ThymineD. AdenineE. Cytosine
73. Which of the following bonds link the monomeric units of nucleic acids?
A. IonicB. PeptideC. ThioesterD. GlycosidicE. Phosphodiester
74. In the DNA molecule, guanine on 1 strand is joined to cytosine on the complementary strand by which of the following bonds?
A. Amide B. 1 hydrogenC. 2 hydrogenD. 3 hydrogenE. Phosphodiester
75. As DNA is denatured, each of the following events take place EXCEPT one. Which event is this EXCEPTION?
A. Total G-C content of total DNA increasingB. UV light absorption increasingC. Complementary strands becoming random
coilsD. Base stacking becoming disruptedE. Hydrogen bond breaking
76. Which of the following are NOT produced by the hydrolysis of nucleic acids?
A. PentosesB. PhosphatesC. Amino acidsD. Purine basesE. Pyrimidine bases
77. The function of which of the following types of nucleic acid is to activate and select specific amino acids for protein synthesis?
A. rRNAB. mRNAC. cDNAD. tRNAE. hnRNA
78. If the molar percentage of A (adenine) in a native DNA specimen is 22%, then what is the molar content of G (guanine)?
A. 22%B. 28%C. 44%D. 56%E. 78%
79. The degenerate nature of the genetic code implies
A. a common tRNA for at least two amino acids.B. that a remarkable degree of inaccuracy
occurs in transcription.C. the existence of multiple codons for each
amino acid.D. the existence of multiple species of
ribosomes for control of messenger translation.
NUCLEIC ACIDS (Continued)
10
80. Transcription is the cellular process of making
A. new DNA.B. RNA from DNA.C. proteins from amino acids by way of RNA.D. none of the above.
81. Which of the following is true of the Tm (melting temperature) of a given DNA double helix?
A. Is a function of the base compositionB. Can be used to accurately predict its
molecular weightC. Can be measured by observing the change
in chemical compositionD. Is higher if individual strands of the DNA
double helix are parallel rather than antiparallel
82. DNA damage by ultraviolet light is due to
A. alkylation of the guanine in DNA.B. excessive unwinding of the DNA moleculeC. frequent replacement in the DNA molecule
of purines by pyrimidines.D. induction of dimerization by way of covalent
bonds between adjacent thymine groups.
83. Each of the following is involved in gene cloning EXCEPT one. Which one is this EXCEPTION?
A. DNA ligaseB. RNA polymeraseC. DNA polymerase ID. Restriction nucleasesE. Reverse transcriptase
84. Plasmid vectors suitable for cloning have which of the following characteristics?
A. Must be able to replicate synchronously with the host chromosome
B. Several unique recognition sequences for one restriction enzyme
C. Two genes conferring resistance to different antibiotics
D. Large size to facilitate plasmid’s entry into cells
85. The polymerase chain reaction is MOST useful for which of the following?
A. Preparing enzymes that synthesize nucleic acids
B. Isolating the genome of an organismC. Amplifying a specific DNA sequenceD. Separating polyclonal antibodiesE. Synthesizing RNA and DNA
LIPIDS
86. Which of the following is LEAST descriptive of lipids?
A. NonpolarB. Carbon-containingC. AmphipathicD. Hydrophilic
87. Which of the following substances represents an unsaturated fatty acid?
A. CholesterolB. PalmitateC. StearateD. CholineE. Oleate
88. Upon complete hydrogenation, oleic, linoleic and linolenic acids yield
A. stearic acid.B. myristic acid.C. palmitoleic acid.D. arachidonic acid.E. multiple acetate fragments.
89. Which of the following classes of steroids contain 18 carbons and an aromatic ring?
A. EstrogensB. AndrogensC. ProgestagensD. GlucocorticoidsE. Mineralocorticoids
LIPIDS (Continued)
11
90. Gangliosides are glycolipids found on various cell surfaces. In addition to sphinogosine, their unit composition contains another characteristic component. This component is
A. uronic acid.B. plasmalogen.C. triglyceride.D. N-acetylmuramic acid.E. N-acetylneuraminic acid.
91. Neutral fats contain mixtures of one or more fatty acids esterified with
A. sterol.B. glycerol.C. lecithin.D. sphinogosine.E. alcohols of high molecular weight.
92. In addition to phosphoric acid, which of the following are the products of hydrolysis of lecithin?
A. Glycerol, fatty acids, serineB. Glycerol, fatty acids, cholineC. Sphingosine, acetic acid, inositolD. Glyceraldehyde, fatty acids, cholineE. Glyceraldehyde, fatty acids, ethanolamine
93. Which of the following is an essential fatty acid?
A. AceticB. StearicC. MyristicD. PalmiticE. Arachidonic
94. Carbon dioxide or bicarbonate is required in the biosynthesis of fatty acids because
A. the bicarbonate/carbonic acid buffer system is very efficient at the pH optimum of this sensitive enzyme system.
B. bicarbonate is a positive effector for this system and favorably alters the conformation of its enzymes.
C. carbon dioxide is incorporated into acetyl coenzyme A forming malonyl coenzyme A, an intermediate in the synthetic process.
D. carbon dioxide is incorporated into carbamyl phosphate, a reactive intermediate in the synthetic process.
E. carbon dioxide provides an anaerobic environment that prevents oxidation of the sulfhydryl groups in the reactive sites of the enzyme system.
95. The enzyme catalyzing the rate-controlling step in the de novo synthesis of fatty acids is regulated allosterically by the positive modulator
A. ATP.B. NADPH.C. Citrate.D. cyclic AMP.
E. oxaloacetate.
96. The pathway of extramitochondrial synthesis of even-numbered fatty acids differs from that of the catabolism of fatty acids in that
A. malonyl CoA is an intermediate in synthesis.B. acyl carrier protein is needed in catabolism.C. no flavoprotein enzymes are required for
catabolism.D. propionyl CoA may serve as an intermediate
in synthesis.
97. Beta oxidation of a mole of an 18 carbon fatty acid under physiologic conditions produces
A. one mole of acetic acid.B. nine moles of acetyl CoA.C. nine moles of acetic acid.D. one mole of acetoacetic acid.E. one mole of hydroxybutyric acid.
LIPIDS (Continued)
12
98. Sodium taurocholate and glycocholate are necessary for the absorption of
A. sucrose.B. glycerol.C. amino acids.D. fatty acids.E. nucleic acids.
99. After functioning in the small intestines, the largest portion of bile salts are
A. excreted in the feces.B. reabsorbed into the central lacteal.C. destroyed by bacteria in the large
intestines.D. reabsorbed into the portal circulation and
reused.E. removed from the circulation by the kidneys
and excreted in the urine.
100. Which of the following is MOST often associated with free fatty acid transport in human blood?
A. AlbuminB. GlobulinC. CholesterolD. SphingolipidE. Mucopolysaccharide
101. Triglyceride absorbed into the lymphatic system is transported to the liver as which of the following?
A. Very low density lipoproteinB. Low density lipoproteinC. ChylomicronsD. LiposomesE. Micelles
102. Which of the following compounds is an intermediate in the biosynthesis of cholesterol?
A. SqualeneB. HexosamineC. Cholic acidD. PregnanediolE. Deoxycholic acid
MEMBRANES
103. The major lipids that make up the cell membrane are
A. triglycerides.B. sphingomyelins.C. phospholipids.D. fatty acids.E. steroids.
104. The most abundant nonphospholipid component of the cell membrane is
A. cholesterol.B. deoxycholate.C. prostaglandin.D. macroglobulin.E. triacylglyceride.
105. Each of the following lipid classes is incorporated into membranes EXCEPT one. Which one is this EXCEPTION?
A. CholesterolB. GangliosideC. TriglycerideD. SphingomyelinE. Phosphatidylcholine
106. Which of the following represents a polyunsaturated fatty acid that is commonly found in animal cell membranes?
A. OleicB. LacticC. SialicD. StearicE. Linoleic
MEMBRANES (Continued)
13
107. The fluid-mosaic model for membrane structure proposes that
A. the outer and inner faces of the membrane are identical.
B. peripheral proteins are situated only on the outer face of the plasma membrane.
C. integral proteins are associated with the hydrophobic phase of the bilayer.
D. both polar and nonpolar ends of membrane phospholipids are within the hydrophobic phase of the bilayer.
108. The major driving force for formation of a lipid micelle is
A. protein-lipid interaction.B. hydrophobic interaction between
hydrocarbon tails.C. hydrogen bonding between water
molecules of the micellar core.D. electrostatic interaction between the
micellar core and polar heads.
109. Which of the following molecules would likely form a micelle when mixed with water and agitated?
A. SerineB. GlycerolC. PhospholipidD. Triglyceride
110. The rapid movement of a substance across a biologic membrane against a concentration gradient requires
A. that the substance be negatively charged.B. participation of an energy-requiring active
transport system.C. that the substance be readily soluble in the
lipid barrier of the membrane.D. that the substance be carried across the
membrane by rapid influx of the solvent.E. facilitated diffusion of the substance aided
by some binding system in the membrane
111. Mediated (facilitated) diffusion of substances across cell membranes differs from simple diffusion in that mediated diffusion
A. requires ATP.B. requires another solute.C. is a one-directional process.D. exhibits saturation kinetics.
112. Which of the following features distinguishes active transport from facilitated diffusion?
A. SpecificityB. Carrier-mediatedC. Requires metabolic energyD. Presence of a transport maximum (Tm)
METABOLISM
113. Reactions that have unfavorable energetics (i.e., + ∆G0) in metabolic pathways may be driven to completion by which of the following processes?
A. CouplingB. AllosterismC. ModificationD. Microscopic reversibility
114. A common intermediate of metabolism of carbohydrates, fatty acids and amino acids is
A. glycerol.B. acetyl CoA.C. acetoacetate.D. oxaloacetate.E. acetylcholine.
METABOLISM (Continued)
14
115. A number of catabolic pathways are allosterically inhibited by an increase in the concentration of which of the following?
A. ADPB. AMPC. ATPD. NAD+
E. Pyruvate
116. In the glycolytic sequence, the enzyme that brings about the transition from 6-carbon metabolites to 3-carbon metabolites is
A. phosphoglucoisomerase.B. phosphofructokinase.C. phosphorylase.D. hexokinase.E. aldolase.
117. Under strict anaerobic conditions, the catabolism of one glucose molecule would yield a net of
A. 2 ATP and 2 lactic acid molecules.B. 4 ATP and 2 lactic acid molecules.C. 2 ATP and 2 pyruvic acid molecules.D. 4 ATP and 2 pyruvic acid molecules.
118. Muscle glycogen does not yield blood glucose directly but liver glycogen does because
A. hexokinase is not present in liver.B. muscle cells are impermeable to glucose.C. muscle does not contain
phosphoglucomutase.D. muscle glycogen differs in structure from
liver glycogen.E. glucose-6-phosphatase is not present in
muscle.
119. Enzymes that catalyze the anaerobic processes of carbohydrate metabolism are found predominantly in which part of a cell?
A. CytoplasmB. MembraneC. Cell wallD. NucleusE. Mitochondria
120. Cyclic 3’, 5’-AMP increases the rate of glycogenolysis by
A. promoting the formation of a phosphorylated form of glycogen phosphorylase.
B. serving as a substrate for glycogen phosphorylase.
C. serving as a precursor of 5’ AMP which is a cofactor for glycogen phosphorylase.
D. furnishing phosphate for the phosphorolysis of glycogen.
121. Consider the conversion: alanine – lactic acid – glucose. This is an example of
A. glycolysis.B. glycogenolysis.C. gluconeogenesis.D. synthesis of glycerol.
122. Energy for ATP synthesis is derived from the electron transport system by which of the following processes?
A. TransaminationB. AldolizationC. Reductive synthesisD. Oxidative deaminationE. Oxidative phosphorylation
METABOLISM (Continued)
15
123. The chemical energy generated by mitochondrial electron transport results from which of the following?
A. Excess H+ in the matrixB. An H+ gradient across the inner
membraneC. The formation of thioesters in the matrixD. A conformational change in the inner
membrane
124. Functions of the hexose monophosphate shunt include the production of
(1) NADP for lactate oxidation.(2) NADPH for fatty acid synthesis.(3) glucuronic acid for heparin synthesis.(4) D-ribose for nucleic acid synthesis.(5) ATP for anaerobic muscle contraction.
A. (1), (3), and (5)B. (1) and (4)C. (2), (3), and (5)D. (2) and (4)E. (3) only
125. Which of the following represents the chemical substance that is the immediate source of energy for muscle contraction?
A. GlycogenB. Acetyl CoAC. Lactic acidD. Creatine phosphateE. Adenosine triphosphate
126. The tricarboxylic acid cycle is initiated by the condensation of which of the following two molecules?
A. Pyruvate and malateB. NAD+ and oxaloacetateC. NAD+ and oxalosuccinateD. Acetyl coenzyme A and oxaloacetateE. Acetyl coenzyme A and oxalosuccinate
127. Enzymes concerned with the citric acid cycle are found in the
A. nucleus.B. ribosomes.C. mitochondria.D. nonparticulate cytoplasm.E. None of the above
128. Acids found in the citric acid (Krebs) cycle are
A. glutamic acid and succinic acid.B. glucuronic acid and aspartic acid.C. oxaloacetic acid and aspartic acid.D. oxaloacetic acid and pyruvic acid.E. oxaloacetic acid and α-ketoglutaric acid.
129. If protein is catabolized for energy, then MOST of the energy is derived from which of the following?
A. Urea productionB. Oxidative deaminationC. Transamination reactionsD. Cleavage of peptide bondsE. Oxidation of α-keto acids derived from
amino acids.
130. Which of the following is the FIRST step in the catabolism of many amino acids?
A. Formation of a dipeptide with glutamate B. Conjugation of the alpha amino to
glucuronateC. Transamination of the alpha amino to a
keto acidD. Conjugation of the alpha carboxyl group to
glucuronateE. Decarboxylation of the alpha carboxyl
group to form a primary amine
METABOLISM (Continued)
16
131. Which of the following statements is NOT true about ammonia and the α-amino group of amino acids?
A. NH+4 is formed from glutamine in the
kidney.B. The amino group in carbamyl phosphate is
directly donated by aspartate in a transamination reaction.
C. Cellular levels of ammonia must be maintained at low concentrations because of its toxicity.
D. Glutamate dehydrogenase can catalyze the formation of glutamate from ammonia and α-ketoglutarate using NADPH as a cofactor.
132. The level of nonprotein nitrogen in the blood is due principally to the level of which of the following?
A. UreaB. AmmoniaC. CreatineD. ArginineE. Uric acid
133. What is the product P in the following reaction?
α-ketoglutarate + alanine = pyruvate + P
A. GlutamateB. GlutamineC. AspartateD. SuccinateE. Pyridoxine phosphate
134. Which of the following tissues is primarily responsible for formation of urea?
A. LiverB. BrainC. KidneyD. Muscle
135. After prolonged acidosis, which of the following represents the nitrogenous product that is excreted in high amounts in the urine?
A. UreaB. AmmoniaC. Uric acidD. CreatinineE. Aspartic acid
136. Excessive utilization of fats by the body as a source of energy during disturbances in carbohydrate metabolism can lead to all of the following conditions EXCEPT
A. ketosis.B. acidosis.C. ketonuria.D. alkalosis.
137. In relative insulin insufficiency, acetyl CoA is usually channeled into
A. ketone-body formation.B. cholesterol synthesis.C. fatty-acid synthesis.D. gluconeogenesis.E. the Krebs cycle
138. The ketone body acetoacetate is synthesized inside mitochondria of hepatocytes by
A. carboxylation of pyruvic acid.B. transamination of aspartic acid.C. cleavage of β-hydroxy- β-methylglutaryl
CoA.D. oxidative decarboxylation of α-
ketoglutarate.E. oxidation of L-β-hydroxybutyrate followed
by deacylation.
METABOLISM (Continued)
17
139. The final step in the complete metabolism of fat is carried out by means of
A. anaerobic glycolysis.B. the tricarboxylic acid cycle.C. the reductive fixation of CO2.D. the hexose monophosphate shunt.E. the Krebs-Henseleit (urea) cycle.
140. Mobilization of fat stored in adipocytes involves
A. activation of fatty acids by synthesis of acyl CoA.
B. rearrangement of fatty acids in triglycerides.
C. phosphorylation of glycerol at the expense of ATP.
D. activation of triglyceride lipase by ADP.E. activation of triglyceride lipase by a cAMP
dependent protein kinase.
141. How do inadequate insulin levels, such as those which occur in diabetes mellitus, affect fat metabolism?
A. Glucose utilization is increased.B. Utilization of fat for energy is increased.C. Storage of cholesterol by the Kupffer cells
is increased.D. Level of beta-hydroxybutyric acid in the
urine is depressed.
142. Prostaglandins are made within cells
A. on an RNA template.B. on rough endoplasmic reticulum.C. from methionine.D. from progesterone.E. from polyunsaturated fatty acids.
143. The metabolite, 25-hydroxycholecalciferol is derived MOST immediately from
A. ergosterol.B. cholesterol.C. 7-dehydro-sitosterol.D. 7-dehydro-cholesterol.E. 22-dihydro-ergosterol.
144. Which of the following is necessary for de novo synthesis of cholesterol?
A. NAD+
B. NADHC. NADP+
D. NADPHE. FADH2
145. Most endogenous cholesterol in the liver is usually converted into which of the following?
A. GlucoseB. SteroidsC. Cholic acidD. OxaloacetateE. Ketone bodies
146. Ribose phosphate needed for nucleic acid synthesis can be derived from
A. gluconeogenesis.B. the pentose phosphate pathway.C. the Krebs’ tricarboxylic acid cycle.D. decarboxylation of aromatic amino acids.E. one-carbon transfer from tetrahydrofolate
derivatives.
147. Purine ribonucleoside phosphates are all synthesized de novo from the common intermediate
A. inosine phosphate.B. guanosine phosphate.C. adenosine phosphate.D. guanosine diphosphate.E. deoxyadenosine phosphate.
148. Which of the following enzymes catalyzes the formation of uric acid from purines?
A. UreaseB. UricaseC. Xanthine oxidaseD. Aspartate transcarbamoylaseE. Carbamoyl-phosphate synthetase
METABOLISM (Continued)
18
149. Which of the following is a source of transferable methyl groups in metabolism?
A. ValineB. CholineC. LeucineD. Isoleucine
150. Coenzyme A participates in
A. formylation.B. protein synthesis.C. methionine activation.D. activation of carboxyl groups.
151. Tay-Sach disease is associated with an inborn error of metabolism involving a specific enzyme which normally degrades a particular molecule in the gray matter. This enzyme acts on which of the following?
A. PolysaccharidesB. AcylglycerolsC. GangliosidesD. Fatty acidsE. Proteins
152. Glucosuria with hyperglycemia usually occurs in which of the following?
A. PellagraB. Addison’s diseaseC. Diabetes mellitusD. Diabetes insipidusE. Parkinson’s disease
VITAMINS
153. Which of the following is a vitamin?
A. AdenineB. InosineC. XanthineD. ThyroxinE. Pyridoxine
154. The general reaction for the transfer of a “one-carbon fragment” requires the coenzyme
A. pyridoxal phosphate.B. tetrahydrofolic acid.C. thiamine pyrophosphate.D. flavin adenine dinucleotide.E. diphosphopyridine nucleotide.
155. Pantothenic acid is an integral part of
A. NAD+.B. cobalamin.C. folic acid.D. coenzyme A.E. pyridoxine phosphate.
156. Derivatives of riboflavin and niacin function as
A. CO2 acceptorsB. coenzymes in redox reactions.C. factors in transamination reactions.D. replacements for each other in biologic
reactions.
157. A vitamin derivative concerned with conversion of glucose to lactic acid is
A. thiamine (as cocarboxylase).B. pantothenic acid (as coenzyme A).C. pyridoxal (as pyridoxal phosphate).D. nicotinamide (as nicotinamide adenine
dinucleotide).
158. Which of the following vitamins is necessary as a coenzyme in the initial steps of fatty acid synthesis?
A. BiotinB. ThiamineC. Vitamin AD. Vitamin DE. Riboflavin
VITAMINS (Continued)
19
159. Which of the following is required for vitamin D3 synthesis?
A. Decarboxylation in the liverB. UV activation of precursors in skinC. Metabolism by gut bacteriaD. Deamination in the kidney
160. Hydroxylation at the 1 position of 25-hydroxycholecalciferol occurs primarily in the
A. skin.B. liver.C. kidney.D. intestinal mucosa.
161. Vitamin A functions to
A. prevent pellagra.B. promote absorption of calcium.C. promote differentiation of epithelial cells.D. maintain the integrity of connective
tissues.
162. A deficiency of vitamin A in a developing tooth most likely affects the
A. pulp.B. enamel.C. dentin.D. cementum.
163. The effect of a vitamin C deficiency on the developing tooth is primarily on the calcification of dentin and cementum. This can best be explained by which of the following statements?
A. This does happen, but the reason is obscure.
B. Dentin is the most sensitive tissue in the body to a vitamin C deficiency.
C. Vitamin C influences the formation of collagen, the organic matrix found in dentin and cementum.
D. Vitamin C has metabolic interrelations with other vitamins that have a greater influence on dentin and cementum than on enamel.
E. The vascular system is more important to these tissues than to enamel and, in an avitaminosis C, the vascular system is subject to hemorrhage.
164. Which of the following is a function of vitamin B6 (pyrodoxal phosphate)?
A. Prevents pernicious anemiaB. Allows adaptation to dim lightC. Acts as coenzyme in transamination
reactionD. Prevents microcytic hypochromic anemia
165. Which of the following is NOT involved as a cofactor in formation of acetyl CoA from pyruvate?
A. NAD+
B. FADC. PyridoxineD. Lipoic acidE. Thiamine pyrophosphate
166. A derivative of vitamin K is the coenzyme for which of the following?
A. Production of menadiolB. Esterfication of retinolC. Hydrolysis of peptide bondsD. Cross-linking of fibrinogenE. Carboxylation of glutamate side chains
VITAMINS (Continued)
20
167. The function of vitamin K is involved directly with
A. synthesis of prothrombin.B. activation of the Stuart factor.C. regulation of calcium in the blood.D. conversion of fibrinogen to fibrin.E. transcriptional control for fibrinogen
synthesis.
168. Which of the following vitamins can be supplied to humans by the normal action of intestinal flora?
A. AB. DC. ED. KE. None of the above
169. Osteoblasts form the organic matrix of bone prior to calcification of the tissue. This process requires vitamins
A. A and B12.B. A and C.C. A and D.D. C and E.E. D and E.
170. To which of the following avitaminoses is the gingival most susceptible?
A. AB. B2
C. B6
D. CE. Niacin
NUTRITION
171. Some amino acids need not be present in the diet of an animal because of the animal’s ability to synthesize the acids at an adequate rate. A principal source of carbon for these amino acids is
A. nucleic acids.B. carbon dioxide.C. metabolism of carbohydrates.D. methylene folic acid derivatives.
172. Negative nitrogen balance (nitrogen excretion > intake) may be cause by
A. growth.B. protein synthesis.C. dietary lack of essential amino acid.D. synthesis and catabolism of equal
amounts of body protein.
173. Which of the following groups includes only amino acids essential for humans?
A. Valine, serine, leucineB. Leucine, lysine, glycineC. Tyrosine, threonine, tryptophanD. Phenylalanine, methionine, prolineE. Tryptophan, methionine, isoleucine
174. Which of the following amino acids lessens the need for phenylalanine?
A. LysineB. LeucineC. GlycineD. TyrosineE. Tryptophan
175. A diet rich in tryptophan offsets a deficiency of which of the following vitamins?
A. NiacinB. ThiamineC. RiboflavinD. None of the above
176. A deficiency of rhodopsin is most likely caused by decreased dietary intake of
A. glucose.B. adenine.C. vitamin A.D. tryptophan.E. riboflavin.
NUTRITION (Continued)
21
177. Lipid is required in the average diet because it
A. has a high caloric value.B. provides essential fatty acids.C. aids in absorption of carbohydrates.D. is necessary for storage of carbohydrates.
178. A deficiency of choline in the diet can cause abnormalities in the metabolism of
A. lipids.B. proteins.C. minerals.D. carbohydrates.E. nucleoproteins.
179. Purine bases taken in the human diet in the form of DNA or RNA are mostly
A. excreted as urea.B. excreted in the form of uric acid.C. reused and converted to ATP needed as a
source of energy.D. broken down to give NH3 and either
malonic acid or methylmalonic acid.
180. Which of the following minerals are most frequently in short supply in American diet?
A. Calcium and ironB. Calcium and iodineC. Sulfur and potassiumD. Iodine, magnesium and iron
181. Which of the following represents the amount of dietary calcium normally absorbed from the gut of an adult man?
A. An amount less than 50%B. An amount between 60-70%C. An amount between 80-100%D. An amount dependent up the mucosal
ferritin level
182. A diet deficient in calcium will result in
A. stimulation of the thyroid gland.B. increased ability to cross-link fibrin.C. production of calcitonin and a low blood
calcium level.D. production of parathyroid hormone and
bone resorption.
183. The recommended daily dietary allowances for Ca and P provide a Ca/P intake of approximately
A. 0.5.B. 1.0C. 2.0.D. 3.0.E. 4.0.
184. Which of the following must be digested before being in a form that can be absorbed by enterocytes?
A. MonoglyceridesB. Fatty acidsC. FructoseD. GlycineE. Maltose
185. Which of the following is secreted more during the absorptive state than during the postabsorptive state?
A. InsulinB. GlucagonC. CortisolD. ThyroxineE. Ephinephrine
186. A sustained, severe carbohydrate deficiency in the diet will result in which of the following?
A. KetoacidosisB. Severe metabolic alkalosisC. A deficiency in prostaglandin formationD. An inability to synthesize ascorbic acid
HORMONES
22
187. Which of the following hormones is a polypeptide?
A. EpinephrineB. TestosteroneC. ProgesteroneD. TriiodotyronineE. Follicle-stimulating hormone
188. Iodine is primarily important in the biochemical synthesis of
A. ACTH.B. thyroxin.C. adrenalin.D. calcitonin.E. parathyroid hormone.
189. Which of the following hormones is NOT synthesized from cholesterol?
A. ProgesteroneB. TestosteroneC. EstradiolD. CortisolE. Relaxin
190. In which of the following combinations is the name of the hormone, its chemical type and its tissue of origin correctly matched?
A. Aldosterone-peptide-pancreasB. Glucagon-peptide-adrenal cortexC. Epinephrine-steroid-adrenal medullaD. ACTH-polypeptide-adrenal cortexE. Vasopressin-peptide-posterior pituitary
191. Each of the following characterizes a peptide hormone EXCEPT one. Which one is this EXCEPTION?
A. Stored in secretory granulesB. Synthesized in a precursor formC. Binds to intracellular receptorsD. Acts by generating a second messengerE. Usually transported unbound in plasma
192. Which of the following generates a slowly developing long-term response in target tissues by binding to an intracellular receptor?
A. GlucagonB. EstrogenC. ProlactinD. Growth hormoneE. Parathyroid hormone
193. The intracellular, “second” messenger for many peptide and polypeptide hormones is
A. AMP.B. ATP.C. cyclic AMP.D. adenylate cyclase.E. a cytoplasmic receptor.
194. Epinephrine causes an elevation in cAMP levels in muscle cells which in turn activate
A. ATPase.B. adenyl cyclase.C. glycogen synthetase.D. glycogen phosphorylase.E. glycogen phosphorylase phosphatase.
195. The hyperglycemic effect of glucagon is mediated primarily through
A. the growth hormone.B. muscle glycolysis.C. liver glycogenolysis.D. inhibition of cortisol action.E. enhanced glucose reabsorption by renal
tubules.
196. Two hormones which act similarly to increase glycogen and lipid breakdown as well as cyclic AMP synthesis are
A. insulin and calcitonin.B. glucagon and epinephrine.C. aldosterone and testosterone.D. parathyroid hormone and glucagon.
197. Which of the following takes place as proinsulin is converted to insulin?
A. Disulfide bonds are formed.B. Disulfide bonds are broken.C. The polypeptide chain is lengthened.D. A segment of the polypeptide chain is
removed.
198. Which of the following hormones does NOT induce activation of adenylate cyclase?
A. InsulinB. GlucagonC. EpinephrineD. Parathyroid hormone
23
HORMONES (Continued)
199. Inhibition of lipolysis, stimulation of protein synthesis and increased entry of glucose into muscles and adipose tissues are biologic actions of the hormone
A. insulin.B. cortisol.C. glucagons.D. epinephrine.E. testosterone.
200. Which of the following is a principal action of insulin?
A. To mobilize lipid depositsB. To enhance cell permeability to glucoseC. To decrease cell permeability to glucoseD. To conserve glucose by breaking down
amino acids
201. Aldosterone is normally associated with partial regulation of which of the following processes?
A. Sodium balanceB. GluconeogenesisC. Lipid digestionD. Protein degradationE. Carbohydrate metabolism
202. Which of the following BEST explains the primary action of antidiuretic hormone?
A. It decreases the activity of the Na-K pump in the distal tubule.
B. It increases the H2O permeability of the collecting ducts and the distal tubules.
C. It decreases the pore size of the distal tubules and the collecting ducts.
D. It decreases the glomerular filtration rate.E. It inhibits the action of glutaminase.
203. The parathyroid hormone acts in the body by
A. decreasing absorption of calcium in the intestinal tract.
B. accelerating the removal of calcium and phosphate from the skeleton but not from the teeth.
C. stimulating gluconeogenesis in the liver.D. decreasing the excretion of sodium and
chloride.E. All of the above
204. Each of the following is an effect of parathyroid hormone EXCEPT one. Which one is this EXCEPTION?
A. Stimulation of 1-alpha-hydroxylase in kidney
B. Stimulation of osteoclastic activity in boneC. Stimulation of calcium reabsorption by
kidneyD. Inhibition of phosphate reabsorption by
kidneyE. Inhibition of intestinal absorption of
calcium
205. Hyperparathyroidism is marked by
A. chronic tetany.B. a high blood calcium level.C. retention of phosphates by the kidneys.D. storage of excess minerals in the bones.E. increased irritability of excitable tissues.
206. The low serum phosphate level in hyperparathyroidism is caused by
A. increased renal loss of phosphate.B. decreased absorption of phosphate.C. increased deposition of calcium phosphate
in bone.D. increased reabsorption of calcium
phosphate from bone.
HORMONES (Continued)
24
207. A parathyroidectomized animal will exhibit which levels of calcium and phosphate ion concentration in the plasma?
Calcium Phosphate ion concentration
A. Low HighB. Normal LowC. High LowD. Normal NormalE. Low Low
208. Which of the following are the immediate effects of calcitonin on serum levels of calcium and phosphate?
Serum calcium Serum phosphate
A. Increased IncreasedB. Increased DecreasedC. Decreased DecreasedD. No change IncreasedE. Decreased No change
209. Hydrolysis of thyroglobulin liberates a number of iodinated compounds. Two are considered thyroid hormones. These are
A. tyrosine and thyronine.B. tyrosine and diiodotyrosine.C. thyroxin and triiodothyronine.D. thyroxin and triiodotyrosine.
210. Thyroid hormones, glucocorticoids and gonadal steroids are similar in that each
A. is derived from cholesterol.B. is derived from amino acids.C. acts on only one target organ or tissue.D. is released in response to signals from
the hypothalamic-anterior pituitary complex.
E. is released in response to signals from the hypothalamic-posterior pituitary complex.
211. Which of the following describes the principal mechanism by which glucocorticoids stimulate their target cells?
A. They activate specific genes.B. They activate initiation factors for protein
synthesis.C. They increase the intracellular Ca++
concentration.D. They allosterically modify adenylate
cyclase activity.E. They bind to cell membrane receptors and
activate adenylate cyclase.
212. The physiologically active form of vitamin D produced in the kidney is
A. 1,25-dihydroxycholecalciferol.B. 25-hydroxycholecalciferol.C. 7-dehydrocholesterol.D. cholecalciferol.E. ergosterol.
213. The gallbladder is caused to contract by the hormone
A. gastrin.B. secretin.C. pancreozymin.D. enterogastrone.E. cholecystokinin.
214. Secretin functions in digestion of proteins by increasing
A. flow of bile.B. secretion of pepsin.C. flow of pancreatic juice.D. secretion of carboxypeptidase.
215. Androgens are produced in the testis and
A. adrenal cortex.B. thyroid.C. adrenal medulla.D. pituitary.E. hypothalamus.
FLUORIDE
25
216. The mechanism of systemic fluoride action in reducing dental decay is most likely the result of
A. an increase in hardness of the tooth.B. an inhibition of proteolytic enzymes.C. deposition of CaF2 in areas of enamel
susceptible to bacterial penetration.D. an increase in carbohydrate metabolism in
the oral cavity as a result of enzyme inhibition.
E. a reduction in rate of solubilization of enamel as fluoride content of the tissue increases.
217. Fluoroapatite can form during hard tissue formation by a (an)
A. substitution of OH ions by F ions.B. reaction between CaF2 and CaHPO4.C. reaction of F ions with hydroxylysine
residues.D. absorption of F ions onto hydroxyapatite
crystal surfaces.
218. Which of the following statements is NOT true concerning fluoride?
A. It is expected rapidly by the kidney.B. It is deposited in calcified tissues.C. It occurs only in the ionic form in plasma.D. It passes the placental barrier relatively
slowly.E. At 1 ppm. In water, it is tasteless, odorless
and colorless.
219. The anticaries effect of fluoride is LEAST related to which of the following?
A. Ion exchangeB. Decreased solubilityC. Facilitation of remineralizationD. Its presence during enamel formationE. Activation of plaque polysaccharide
hydrolysis
220. The rate of fluoride incorporation into bone depends upon the
A. water-mineral ratio.B. age of the individual.C. rate of bone remodeling or turnover.D. amount of ionizable fluoride in the diet.E. All of the above
221. Sodium fluoride inhibits glycolysis by affecting which of the following?
A. AmylaseB. EnolaseC. PhosphataseD. Phosphorylase
BLOOD CLOTTING
222. A deficiency in vitamin K would affect blood clotting chiefly by
A. decreasing prothrombin production.B. preventing the contraction of the clot.C. preventing the reaction of thrombin with
fibrinogen.D. preventing the conversion of fibrinogen to
fibrin.E. preventing the conversion of prothrombin
to thrombin.
223. Platelets play an important role in hemostasis. Which of the following describes this role?
A. They convert fibrinogen to fibrin.B. They agglutinate and plug small, ruptured
vessels.C. They initiate fibrinolysis in thrombosis.D. They supply fibrin stabilizing factor.E. They supply proconvertin for
thromboplastin activation.
BLOOD CLOTTING (Continued)
26
224. Administration of heparin to a human results in symptoms similar to vitamin K deficiency in that both conditions result in
A. release of lipoprotein lipase to the blood and rapid clearance of chylomicrons.
B. and increase in bleeding time due to lack of thrombin formation.
C. retardation of fibrinogen synthesis by the liver.
D. elevated non-esterified fatty acids which chelate serum calcium, thus retarding blood clotting.
225. Which of the following compounds is NOT involved in coagulation of blood?
A. Fe+2
B. Ca+2
C. ProthrombinD. FibrinogenE. Thromboplastin
226. Which of the following represents the normal substrate of thrombin?
A. FibrinB. ThrombospondinC. ProthrombinD. ThromboplastinE. Fibrinogen
227. Which of the following ions is involved in blood clotting?
A. IronB. SodiumC. CalciumD. Potassium
BONES AND TEETH
228. The organic matrix of bone is composed largely of collagen and
A. lipids.B. citrate.C. dextrans.D. glycosaminoglycans.
229. Which of the following represent(s) the matrix proteins of enamel?
A. Carboxylglutamic acid containing proteinsB. Type I collagenC. AmelogeninsD. ProteoglycansE. Elastin
230. Which of the following explains why enamel is harder than bone?
A. Enamel crystals are larger and more firmly packed.
B. Enamel contains amelogenins in its organic matrix.
C. Enamel contains more magnesium and carbonate.
D. Enamel crystals have more surface area.E. Enamel contains more collagen.
231. Which of following is the major protein component of cementum?
A. ElastinB. KeratinC. CollagenD. AmelogeninE. Osteonectin
232. Which of the following noncollagenous protein components BEST characterizes dentin matrix?
A. LamininB. VimentinC. PhosphophorynD. OsteonectinE. Fibronectin
233. Which of the following has a high affinity for binding calcium and collagen in the calcifying matrix?
A. CalcitoninB. OsteogeninC. OsteonectinD. AmelogeninE. Fibronectin
BONES AND TEETH (Continued)
27
234. Protein content of enamel from mature teeth is approximately what per cent of enamel weight?
A. 0.1-1%B. 5-10%C. 15-20%D. 25-30%E. 50-55%
235. Which of the following functions of bone could be considered the most prominent?
A. Buffering B. Phosphate sourceC. Sodium reservoirD. Fluoride reservoirE. Calcium reservoir
236. Which of the following BEST characterizes hydroxyapatite?
A. Has an amphiphilic surfaceB. Contains 12 ions per unit cellC. As found in bone and enamel contains no
ion substitutionsD. Has a higher solubility product constant
than fluoroapatite
237. The lack of which of the following substances during tooth formation most likely induces enamel hypoplasia?
A. Vitamins A and DB. Vitamins C and DC. Vitamins C and KD. Phosphorus and ironE. Calcium and fluoride
238. Which of the following vitamins is the LEAST likely to be involved in tooth development and calcification?
A. AB. B1
C. CD. D
239. Which of the following is NOT a theory of the effect of parathyroid hormone on bone?
A. The hormone influences the rate of bone resorption.
B. The hormone causes a decrease in new bone formation.
C. The action on bone is related to its action on phosphate excretion.
D. The effect of parathyroid extract is to influence osteoclastic activity.
240. The primary effect of calcitonin is to
A. increase bone resorption.B. inhibit bone resorption.C. increase calcium absorption from the
intestine.D. decrease calcium absorption from the
intestine.
241. Which of the following sweeteners is non-nutritive as well as non-cariogenic?
A. D-fructoseB. SaccharinC. GalactoseD. SorbitolE. Maltose
242. The extracellular polysaccharides synthesized by cariogenic streptococci in the presence of excess sucrose are best described as
A. amylase.B. amylopectin.C. mucopolysaccharide.D. glycogen-like glucan.E. dextran-like glucan.
243. Which of the following represents a soluble polysaccharide found in dental plaque and is formed from the fructose moiety of sucrose?
A. LevanB. DextranC. AmylopectinD. Hyaluronic acid
28
BIOCHEMISTRY NATIONAL BOARD EXAM REVIEW
ANSWERS and COMMENTARY
BASIC CHEMISTRYThere are usually 1-2 basic chemistry questions.
1. D2. A Same question in 1987 and 1998.3. B Same question in 1985 and 1998.4. B5. B6. D7. A
BUFFERS AND pH
8. C A question on the Henderson-Hasselbalch question appeared on exams in 1978, 1982, 1985, and 1998. Know this fundamental equation.
9. C Same question in 1989 and 1996.10. B Very similar question in 1996 and 1998.11. D Be familiar with physiologic buffers.12. A13. C
BICARBONATE/CO2
There are usually 1-2 questions covering carbonic acid, bicarbonate and CO2.
14. D Same question in 1978, 1981, 1985, and 1987.15. B Very similar question in 1978, 1979, 1981 and 1996.16. E A good question on this physiologic buffer system.17. D18. A A variation of this 1998 question on carbonic anhydrase appeared on the 1987
exam.
PROTEINS
19. C The same question appeared on the 1979 and 1985 exams and a variation was on 6 other exams. Know what a peptide bond is as well as the other types of bonds found in proteins (ionic, hydrogen, covalent, hydrophobic, disulfide)
20. B Same question in 1978, 1989, and 1996.21. B22. C23. C24. E Similar questions about types of proteins, as indicated by the choice of answers,
have appeared on several exams. 25. B A question on pI, pH and electrophoresis of a protein or peptide is common.
ENZYMES
26. E27. B28. C Same question in 1981, 1985, and 1987; and a similar question in 1996.29. B Know the definition of the kinetic parameters, Km and Vmax.
30. A Know the characteristics of competitive, non-competitive, uncompetitive and mixed inhibition.
29
31. D Regulation of enzyme activity by phosphorylation is a common question, often in terms of specific enzymes.
32. A Know characteristics of allosteric modifiers.33. D34. B There is frequently a question on enolase because it is inhibited by fluoride.35. A Know the common zymogens and how they are activated.36. D37. C38. B39. A
COLLAGEN
40. D Know all aspects of collagen.41. B42. C43. A Questions on post-translational modifications of collagen are very common.44. D45. E
HEMOGLOBIN
46. D47. C48. D49. A Know the effects of pH, CO2, and 2,3-bisphosphoglycerate on binding of O2 to
hemoglobin.50. E51. A A question related to sickle cell anemia occurs frequently.
PROTEIN SYNTHESIS
52. C53. A54. C55. A56. C57. B58. E
CARBOHYDRATES
59. C A question on sucrose is almost inevitable.60. D A question on configuration is common.61. A62. A63. B64. B65. D66. D67. D Generally there are 2-3 questions on amino sugar compounds and
glycoaminoglycans. (Next two questions for example.)68. E69. D70. D71. A
30
NUCLEIC ACIDSThe number of questions on nucleic acids and molecular biology have increased in recent years.
72. A73. E74. D75. A76. C77. D78. B Know base pairing.79. C80. B81. A82. D83. B84. C85. C
LIPIDSGenerally, lipids are emphasized: different classes of lipids, reactions, metabolism, and functions.
86. D87. E88. A89. A90. E91. B Same question on exams in 1985 and 1987.92. B The same or similar question was on exams in 1979, 1987, and 1996.93. E94. C Same question on exams in 1985, 1987, and 1989. Know fatty acid synthesis
and degradation ( -oxidation). See the following questions.95. C96. A97. B98. D There is usually 1-2 questions on the composition and function of bile salts.99. D The same or similar question appeared on at least 4 exams.100. A101. C Know what the different classes of serum lipoproteins transport and to where.102. A
MEMBRANESQuestions on membranes tend to focus on composition and transport.
103. C104. A105. C106. E107. C108. B109. C110. B111. D112. C
31
METABOLISMCarbohydrate, amino acid, lipid, and nucleotide metabolism are included.
113. A114. B115. C116. E117. A118. E A similar question has been on at least four exams.119. A120. A121. C122. E At least 1 question on electron transport and oxidative phosphorylation is
common. See following question.123. B124. D A good question.125. E The identical question or a similar one has appeared on at least 5 exams.126. D127. C128. E129. E130. C131. B A good question that covers several aspects of amino acid metabolism.132. A133. A134. A135. B136. D At least one question on ketogenesis, ketosis, or ketone bodies is common. See
following two questions.137. A138. C139. B140. E141. B142. E143. D Know cholesterol metabolism.144. D145. C146. B147. A148. C149. B150. D151. C152. C
VITAMINSThere is usually several questions on vitamins because of their involvement in many biological processes.
153. E154. B155. D156. B157. D158. A159. B A question on vitamin D is common.160. C161. C
32
162. B163. C164. C A similar question has appeared on at least 3 exams.165. C166. E Know vitamin K. See following 2 questions.167. A168. D169. B170. D
NUTRITIONNutrition concerns the major food stuffs of carbohydrates, lipids and proteins, essential dietary substances, and micronutrients (vitamins and minerals). Consequently, nutrition is related to some previous subjects and the questions will overlap.
171. C Esential amino acids and related metabolism tend to be emphasized. See following 4 questions.
172. C173. E174. D175. A176. C177. B178. A179. B180. A181. A Know calcium.182. D183. B184. E185. A186. A
HORMONESQuestions cover the chemical composition, biosynthesis, mechanism of action, and physiological functions of hormones.
187. E188. B189. E190. E A good question because it covers different characteristics of a particular
hormone.191. C192. B193. C194. D Know the hyperglycemic (epinephrine, glucagon) and hypoglycemic (insulin)
hormones. See the following 6 questions.195. C196. B197. D198. A199. A200. B201. A A question on aldosterone has appeared on at least 5 exams.202. B A question on antidiuretic hormone (vasopressin) has appeared on at least 7
exams. Occasionally, there is more than 1 question on vasopressin on the same exam.
33
203. B Questions on parathyroid hormone and calcitonin and their regulation of calcium and phosphate levels are emphasized. See the following 5 questions.
204. E205. B206. A207. A208. C209. C210. D211. A212. A213. E214. C215. A
FLUORIDE
216. E This same question has appeared on at least 4 exams.217. A218. C219. E220. E221. B
BLOOD CLOTTING
222. A223. B224. B225. A226. E227. C
BONES and TEETHThe composition and properties of bones and teeth, the effects of hormones and vitamins, and caries are emphasized.
228. D229. C230. A231. C232. C233. C234. A235. E236. D237. A238. B239. B240. B241. B242. E243. A
34
ADDENDUM, JUNE, 2005
In 2004, the American Dental Association released a National Board Comprehensive Part I Pilot Examination. This pilot examination was composed of 400 questions that covered Biochemistry-Physiology; Microbiology-Pathology; Dental Anatomy & Occlusion; and Anatomic Sciences. The exam was divided into two parts with 200 questions on each part (3.5 hrs for each part). Eighty percent of the questions were based on fundamental knowledge similar to those questions in the previous portion of this review material. Twenty percent of the questions were based on clinical cases (“testlets”) that each covered all four of the general subject areas noted above. There were four “testlets” on each part of the pilot exam, which each covered 5 to 13 questions. Below are Biochemistry questions from the pilot exam. I have included some “testlets” from the pilot exam, but have included only the corresponding questions that were identified as Biochemistry. The “testlets” had only a few questions that were specifically Biochemistry. Answers are given at the end of the questions.
pH
A1. Which of the following describes the movement of glycine molecules in an electric field at a pH of 6.06 (the isoelectric pH for glycine)? The glycine molecules will
A. not move.B. move to the anode.C. move to the cathode.D. move to both anode and cathode.
PROTEIN, ENZYMES, HEMOGLOBIN
A2. Which of the following pairs of amino acids is expected to be found on the interior of a globular protein?
A. Lysine and arginineB. Arginine and leucineC. Leucine and valineD. Valine and glutamic acidE. Glutamic acid and lysine
A3. Which of the following is an allosteric effector of an enzymatic reaction?
A. Competitive inhibitorB. Noncompetitive inhibitorC. Substance that binds to the substrateD. Substance affecting enzymatic activity by
binding to the active siteE. Substance affecting enzymatic activity by
binding to non-active sites
A4. Zinc is an essential component of which of the following?
A. PepsinB. AmylaseC. HexokinaseD. Adenylate cyclaseE. Carbonic anhydrase
A5. Which of the following describes a major effect of sickle cell anemia?
A. Absence of biphosphoglycerate binding of hemoglobin
B. Substitution of 2 proximal histidinesC. Decreased solubility of the deoxy form of
hemoglobinD. A P 50 value for hemoglobin similar to that of
myoglobin E. Decreased number of subunits in
hemoglobin
35
COLLAGEN, EXTRACELLULAR MATRIX, ENAMEL
A6. The unique amino acid composition of collagen is reflected in the high content of
A. valine, threonine, and lysine.B. desmosine, glycine, and proline.C. cysteine, tyrosine, and phenylalanine.D. glycine, proline, and hydroxyproline.E. cysteine, hydroxylysine, and proline.
A7. Which of the following is MOST likely to promote depolymerization of extracellular matrix?
A. CortisoneB. CollagenaseC. ChymotrypsinD. Hyaluronidase
A8. Which of the following vitamins is essential for the normal elaboration and maintenance of bone matrix, cartilage, and dentin?
A. NiacinB. Vitamin EC. Ascorbic acidD. Pantothenic acid
A9. Which of the following statements BEST describes hydroxyapatite in enamel?
A. Has a nonpolar surfaceB. Has 10 ions in each unit cellC. Contains no ion substitutionsD. Has a higher solubility than fluorapatiteE. Has a solubility that decreases as the pH
decreases
CARBOHYDRATES
A10. What are predominant linkages in glycogen between glucose units?
A.Alpha-1,4B.Alpha-1,6C. Beta-1,3D. Beta-1,4E.Beta-1,6
A11. Glucose can be made from each of the following substances EXCEPT one. Which one is this EXCEPTION?
A. LactateB. Acetyl CoAC. GlycerolD. PyruvateE. Fructose
A12. Which of the following is the pathway that results in the formation of glucose in the liver from lactate produced in muscle?
A. Cori cycleB. GlycolysisC. Citric acid cycleD. Pentose phosphate pathway
A13. Which of the following mechanisms operates in liver cells to regulate breakdown of glycogen?
A. Zymogen activationB. Phosphorylation of phosphorylase b to
phosphorylase aC. Induction of phosphorylase b by an
inducerD. Inhibition of adenylate cyclase
A14. Glucose-6-phosphatase is found associated with which of the following?
A. Kidneys and liverB. Liver and musclesC. Kidneys and brainD. Kidneys and muscles
36
NUCLEIC ACIDS
A15. Which of the following base pairs promotes helix stabilization in DNA but does NOT do so in RNA?
A.G-CB.A-TC. G-UD. C-TE.A-U
A16. If the anticodon on transfer-RNA is 5’ACG3’, then which of the following is its corresponding codon on messenger-RNA?
A. 5’ CGT 3’B. 5’ CGU 3’C. 5’ TGC 3’D. 5’ UAG 3’E. 5’ UGC 3’
A17. DNA that is complementary to mRNA can be made using which of the following?
A. A plasmidB. DNA ligaseC. A retrovirusD. RNA polymeraseE. Reverse transcriptase
A18. Which of the following represents the consequence of the fact that DNA strands are complementary?
A. Hairpin loop structures can be generatedB. They will always have identical sequencesC. Separated strands are able to reassociateD. They cannot get back together once
separated
A19. Which of the following enzymes seals nicks in DNA?
A. ExonucleaseB. EndonucleaseC. LigaseD. DNA polymeraseE. RNA polymerase
A20. Which of the following BEST describes the major function of histones?
A. Unwind DNA.B. Activate genes.C. Stabilize DNA in a compact form.D. Remove exons during RNA splicing.E. Stabilize RNA during transcription.
A21. Which of the following BEST describes restriction enzymes?
A. ExonucleasesB. TopiosomerasesC. Enzymes that degrade RNAD. Non-specific endonucleasesE. Site-specific endonucleases
A22. Which of the following types of blotting can be used to identify DNA restriction fragments?
A. EasternB. SouthernC. NorthernD. Western
A23. Which of the following enzymes synthesizes polynucleotide chains from nucleotides and does NOT require a primer chain?
A. LigaseB. ExonucleaseC. EndonucleaseD. DNA polymeraseE. RNA polymerase
A24. Which of the following is produced when a mutation occurs in an enzyme controlling a signal pathway involved in cell growth processes?
A. EpigeneB. AntigeneC. OncogeneD. MonogeneE. Transgene
37
LIPIDS
A25. The first step in the pathway for fatty acid synthesis is catalyzed by an allosteric enzyme which is the principal regulator of the pathway. This enzyme is
A. thiolase.B. pyruvate carboxylase.C. citrate synthetase.D. acetyl CoA carboxylase.E. pyruvate dehydrogenase.
A26. Each of the following is expected to be active during fatty acid biosynthesis EXCEPT one. Which one is this EXCEPTION?
A. Tricarboxylic acid cycleB. Pyruvate dehydrogenaseC. Amino acid catabolism D. Beta oxidationE. Glycolysis
A27. Which of the following is a ketone body?
A. GlycerolB. GlucagonC. Acetyl CoAD. AcetoacetateE. Phosphatidycholine
A28. Bile salts are sodium salts of bile acid that are conjugated with
A. cysteine and serine.B. taurine and glycineC. methionine and lysine.D. homocysteine and ornithine.
MEMBRANES/TRANSPORT
A29. Facilitated diffusion DIFFERS from active transport in that net transport by facilitated diffusion
A. has a transport maximum.B. uses ATP as an energy source.C. requires a concentration gradient.D. occurs as an endergonic (positive ΔG)
process.
A30. The cell membrane is LEAST permeable to which of the following substances?
A. O2
B. CO2
C. H2OD. SodiumE. Ethanol
A31. Active transport systems generally involve specific binding molecules that are classified as a
A. lipid.B. protein.C. lipoprotein.D. carbohydrate.E. phospholipid.
A32. Which of the following provides the immediate energy source for the transport of glucose into intestinal epithelial cells?
A. NADHB. NADPHC. Na+ gradient across the luminal
membraneD. H+ gradient across the luminal
membrane
38
METABOLISM
A33. Which of the following substances is the predominant source of ATP at MODERATE levels (for greater than 60 minutes) of activity?
A. Amino acidsB. Fatty acidsC. CarbohydratesD. Proteins
A34. The catabolism of which of the following results in no energy production in the form of ATP?
A. LipidB. ProteinC. NucleotideD. Carbohydrate
A35. Which of the following directly catalyzes urea formation in a cell?
A. UreaseB. UricaseC. ArginaseD. Glutaminase
A36. Which main product of protein nitrogen metabolism is found in human urine?
A. UreaB. AmmoniaC. CreatineD. Uric acidE. Creatinine
A37. Which of the following compound is a precursor of the pigments of the skin, hair, and eyes?
A. TyrosineB. CysteineC. LysineD. CreatineE. Galactosamine
HORMONES
A38. Which of the following promotes the release of bile from the gallbladder?
A. GastrinB. SecretinC. GallaD. BombesinE. Cholecystokinin
A39. Hormones that exert their effects through the activation of second messengers are
A. lipophilic.B. usually water soluble peptide/protein
hormones.C. initially bound to cytoplasmic hormone
receptors.D. secreted by ovaries, testes, adrenal
cortex, and placenta.
A40. Which of the following hormones exerts the LEAST effect on calcium metabolism of bone tissues?
A. AndrogenB. EstrogenC. NorepinephrineD. Thyroid hormoneE. Parathyroid hormone
A41. The biologically active conformation of trimeric G-proteins requires
A. the alpha-subunit to bind GDP.B. the alpha-subunit to bind GTP.C. the hydrolysis of BetaGamma-subunits.D. the alpha-subunit to phosphorylate
downstream targets.
39
VITAMINS/COENZYMES
A42. Each of the following coenzymes is a component of the pyruvate dehydrogenase complex EXCEPT one. Which one is this EXCEPTION?
A. NADB. BiotinC. Coenzyme AD. Thiamine pyrophosphate
A43. Which of the following coenzymes is required for the synthesis of pyrimidines, such as thymine?
A. NiacinB. ThiamineC. Folic acidD. RiboflavinE. Pyridoxine
Testlet 1.
A 23-year-old female present with complaints of difficulty in opening her mouth and a low-grade fever of several days’ duration. The medical history indicates a recent positive PPD skin test, and the patient is taking rifampin (Rifadin®). The extra-oral exam shows diffuse swelling at the angle of the right mandible and lacteral neck. Oral exam shows gingival swelling and erythema around partially erupted Tooth #32.
A44. Rifampin (Rifadin®) is effective in treating active tuberculosis because it targets which of the following pathways?
A. MitosisB. ReplicationC. TranslationD. TranscriptionE. mRNA splicing
Testlet 2.
A 15-year-old male presents for emergency care. He is non-compliant with his type I diabetes regimen, and he suffered a fall while having an insulin reaction. He struck his chin and lacerated his tongue. Upon opening, his mandible deviates to the left. A panoramic radiograph reveals a fracture of the left condylar neck.
A45. Before examining this patient, the dentist notes that the standard medical emergency kit contains an ampule of glucagon. For which of the following reasons would glucagon be used?
A. Acts as a source of glucose for the hypoglycemic patient.
B. Promotes glycogen formation in the hyperglycemic patient.
C. Promotes glycogenolysis in the hypoglycemic patient.
D. Stimulates secretion of insulin in the hyperglycemic patient.
A46. The patient’s “insulin reaction” represented a sudden fall in blood glucose because he had taken his normal insulin dose but did not eat breakfast. Each of the following is a clinical manifestation of hypoglycemia EXCEPT one. Which one is this EXCEPTION?
A. ComaB. DizzinessC. ConfusionD. ConvulsionE. Hyperventilation
A47. Which of the following glucose transporters was responsible for the patient’s “insulin reaction”?
A. GLUT-1B. GLUT-2C. GLUT-3D. GLUT-4E. GLUT-5
40
Testlet 3.
An 80-year-old female with a history of cardiovascular disease presents with a complaint of pain under her complete dentures when biting. She has worn them for 15 years, but seldom removes or cleans them. Removal of the dentures reveals diffuse erythema of underlying mucosal tissue. Bone resorption is noted from detectable reduction in height of the alveolar ridges due to the ill-fitting denture.
A48. The bone resorption seen in elderly patients with low dietary calcium is enhanced by which of the following hormones?
A. InsulinB. EstrogenC. AldosteroneD. Thyroid stimulating hormoneE. Parathyroid hormone
A49. Administration of a local anesthetic with epinephrine will MOST likely produce which of the following cardiovascular effects?
A. Increased heart rateB. Decreased heart rateC. Increased diastolic blood pressureD. Decreased systolic blood pressure
41
Answers for Addendum, June, 2005
A1. A A26. DA2. C A27. DA3. E A28. BA4. E A29. CA5. C A30. DA6. D A31. BA7. D A32. CA8. C A33. BA9. D A34. CA10. A A35. CA11. B A36. AA12. A A37. AA13. B A38. EA14. A A39. BA15. B A40. CA16. B A41. BA17. E A42. BA18. C A43. CA19. C A44. DA20. C A45. CA21. E A46. EA22. B A47. DA23. E A48. EA24. C A49. AA25. D
42
