Download biochemistry national board exam review

BIOCHEMISTRY NATIONAL BOARD EXAM REVIEW
Larry D. Barnes
Department of Biochemistry
University of Texas Health Science Center at San Antonio
June, 2004
Addendum, 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 CHEMISTRY
1. Which of the following characterizes exergonic
reactions?
A.
B.
C.
D.
E.
3.
Decreased entropy
Increased enthalpy
Decreased enthalpy
Negative free energy change
Positive free energy change
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.
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.
2. What thermodynamic parameter is a measure of
randomness or disorder in a system?
A.
B.
C.
D.
E.
Entropy
Enthalpy
Free energy
Potential energy
Activation energy
4. Which of the following substances is LEAST
polar?
A.
B.
C.
D.
Ethanol
Cholesterol
Palmitic acid
Glycocholic acid
6. Which of the following compounds does NOT
contain a high-energy bond?
A.
B.
C.
D.
E.
ATP
Acetyl CoA
UDP-glucose
Glucose-6-phosphate
Phosphoenolypyruvate
7. Which of the following solutions has an osmotic
pressure different from all the others?
A.
B.
C.
D.
E.
1 M glucose
1 M sodium chloride
1 M potassium nitrate
1 N lithium iodide
1 N hydrochloric acid
1
BUFFERS and pH
8. The Henderson-Hasselbach equations shows
that
A.
B.
C.
D.
dilution of a buffer increases its pH.
pH = pka when an acid is 0.1 N
pH = pka when an acid is half neutralized.
pH is independent of the dissociation
constant of the acid
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.
B.
C.
D.
E.
become denatured.
migrate to the negative pole.
migrate to the positive pole.
remain stationary and unchanged.
separate into its different monomeric forms.
12. All of the following function in buffer systems in
the blood EXCEPT
A.
B.
C.
D.
E.
NaCl.
H2C03.
NaHCO3.
Na2HPO4.
NaH2PO4.
9. Which of the following represents the pH of a
solution that has 10-5 M concentration of OHion?
A.
B.
C.
D.
E.
5
7
9
Determine only if the pKa is known.
Determinable only if the base composition is
known.
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.
13. The buffer system most important in maintaining
the physiological pH of plasma is
A.
B.
C.
D.
E.
protein/proteinate
acetic acid/acetate
carbonic acid/bicarbonate
phosphoric acid/phosphate
hydroxybutyric acid/hydroxybutyrate
BICARBONATE/CO2
14. Neutralization of acids by saliva results mainly
from which of the following salivary contents?
15. MOST of the CO2 in blood is combined as
A. H2C03.
A.
B.
C.
D.
E.
Mucin
Ammonia
Carbonate
Bicarbonate
Amino acids
B.
C.
D.
E.
-
HCO 3.
CH3 –COOH.
carbonic acid
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.
B.
C.
D.
E.
compensated alkalosis.
compensated acidosis.
uncompensated alkalosis.
uncompensated acidosis.
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.
B.
C.
D.
E.
Carbonic anhydrase
Alkaline phosphatase
Pyruvate carboxykinase
Histidine decarboxylase
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.
B.
C.
D.
E.
zwitterion.
polypeptide.
peptide bond.
hydrogen bond.
glycosidic bond.
21. Denaturation usually destroys all of the
following bonds in protein EXCEPT
A.
B.
C.
D.
hydrogen bonds.
covalent bonds.
hydrophobic bonds.
electrostatic bonds.
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.
22. Which of the following is the best method for
determining the three-dimensional structure of
protein?
A.
B.
C.
D.
E.
Dialysis
Electrophoresis
X-ray diffraction
Ultracentrifugation
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.
B.
C.
D.
E.
leucine.
alanine.
proline.
tyrosine.
aspartic acid.
24. A mucin is which of the following types of
proteins?
A.
B.
C.
D.
E.
Simple protein
Phosphoprotein
Chromoprotein.
Nucleoprotein.
Glycoprotein.
25. How will a protein respond in an electrophoretic
system, should the pH become lower than the
isoelectric point of the protein?
A.
B.
C.
D.
E.
It will become denaturated.
It will migrate to the negative pole.
It will migrate to the positive pole.
It will remain stationary and unchanged.
It will separate into its different monomeric
forms.
ENZYMES
26. Which of the following is true regarding
enzymes?
A.
B.
C.
D.
Are not reusable
Are needed in large amounts
Catalyze endergonic reactions only
Increase the energy of activation of the
reaction
E. Decrease the energy of activation of the
reaction
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.
27. The optimum pH for an enzyme is the
A.
B.
C.
D.
isoelectric point of the enzyme.
pH of most rapid reaction rate.
pH at which the enzyme is most soluble.
pH of most rapid denaturation of the
enzyme
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.
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.
B.
C.
D.
E.
Allosteric
Competitive
Irreversible
Uncompetitive
Noncompetitive
34. Sodium fluoride inhibits glycolysis by affecting
A.
B.
C.
D.
amylase
enolase
phosphatase
phosphorylase
36. Two enzymes that have been postulated to play
very important roles in calcification are
A.
B.
C.
D.
enolase and phosphorylase.
alkaline phosphatase and catalase.
pyrophosphatase and carbonic anhydrase.
pyrophosphatase and alkaline
phosphatase.
E. carbonic anhydrase and alkaline
phosphatase.
31. Protein kinase regulate the activities of key
enzymes through which of the following?
A.
B.
C.
D.
E.
Oxidation
Hydrolysis
Acetylation
Phosphorylation
Dephosphorylation
33. Enzymes for electron transport reactions are
most active and concentrated in which of the
following structures of the animal cell?
A.
B.
C.
D.
E.
Nuclei
Lysosomes
Microsomes
Mitochondria
All of the above
35. Which of the following enzymes converts
trypsinogen to trypsin?
A.
B.
C.
D.
Enterokinase
Peptidase
Secretin
Pepsin
37. Which of the following enzymes is essentially
absent from normal mammalian muscle?
A.
B.
C.
D.
E.
Glucokinase
Phosphorylase
Glucose-6-phosphatase
Glucose-6-phosphate isomerase
Glucose-6-phosphate dehydrogenase
5
ENZYMES (Continued)
38. Dental plaque arises primarily as a result of
enzymatic reactions using which of the
following?
A.
B.
C.
D.
Sucrose and lipid
Sucrose and saliva
Glucose and saliva
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.
B.
C.
D.
E.
Glucokinase
Aldolase
Hexokinase
Enolase
Glucose-6-phosphatase
COLLAGEN
40. The most abundant protein (by weight) in which
the human body is
A.
B.
C.
D.
E.
elastin.
keratin.
albumin.
collagen.
chondroitin.
42. Which of the following statements concerning
collagen is INCORRECT?
41. Alpha-ketoglutarate, oxygen, and ascorbic acid
are essential for which of the following
processes?
A.
B.
C.
D.
E.
Incorporation of proline
Hydroxylation of proline
Gamma-carboxylation of proline
Oxidative deamination of lysine
Activation of procollagen peptidase
43. Hydroxylation of proline and lysine during
collagen biosynthesis occurs
A. Collagen has a trihelical structure.
B. The molecular weight of collagen is above
100,000
C. 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.
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
45. Which of the following do elastin and collagen
have in common?
A.
B.
C.
D.
E.
chitin.
keratin.
elastin.
collagen.
cellulose.
A.
B.
C.
D.
E.
Easily stretched
Absence of proline
Disulfide crosslinking
Triple helix structure
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
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.
B.
C.
D.
E.
0.5.
less than 1.
almost 2.
greater than 2.
greater than 3.
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.
47. Which of the following is NOT a part of the
hemoglobin molecule?
A.
B.
C.
D.
E.
Iron
Protein
Magnesium
Histidine
Pyrrole ring
49. The affinity of hemoglobin for oxygen
diminishes as which of the following is
decreased?
A.
B.
C.
D.
E.
pH
CO2
Temperature
Hydrogen ion concentration
2, 3 bisphosphoglyceric acid (BPG)
51. Compared with hemoglobin A, the substitution
of a valine for a glutamic acid residue in
hemoglobin S results from
A.
B.
C.
D.
a genetic mutation
irradiation of hemoglobin A.
proteolytic action in the liver.
exposure to low oxygen tension.
7
PROTEIN SYNTHESIS
52. The process by which genetic information flows
from RNA to protein is
A.
B.
C.
D.
mutation.
replication.
translation.
transcription.
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.
B.
C.
D.
E.
DNA.
transfer RNA.
messenger RNA.
ribosomal RNA.
mitochondrial RNA.
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.
53. Which of the following enzymes or processes
ensures that the correct amino acid is
incorporated for a particular codon during
protein synthesis?
A.
B.
C.
D.
E.
Amino Acyl-tRNA synthetase
Ribosomal protein synthesis
Post-transcription splicing
RNA synthetase
Helicase
55. The termination of synthesis of a polypeptide is
believed to involve
A.
B.
C.
D.
E.
nonsense codons.
anticodon-codon interaction.
tRNA which cannot bind amino acids.
hydrolysis of messenger RNA.
none of the above.
57. Streptomycin is an antibiotic which inhibits the
process of
A.
B.
C.
D.
E.
translation in eukaryotes.
translation in prokaryotes.
transcription in eukaryotes.
transcription in prokaryotes.
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.
B.
C.
D.
E.
Proline
Arginine
Tryptophan
Asparagine
Hydroxylysine
CARBOHYDRATES
59. Hydrolysis of sucrose by the enzyme sucrase
yields
A.
B.
C.
D.
E.
glucose only.
glucose and maltose.
glucose and fructose.
glucose and galactose.
fructose and maltose.
60. The arrangement of sugars into D- and Lconfigurations is based upon their resemblance
to D- and LA.
B.
C.
D.
E.
glycine.
glucose.
fructose.
glyceraldehyde.
None of the above
8
CARBOHYDRATES (Continued)
61. Which of the following is NOT a
monosaccharide?
A.
B.
C.
D.
E.
Amylose
Glucose
Fructose
Glyceraldehyde
Glucuronic acid
63. What linkages occur in glycogen at branch
points between glucose units?
A.
B.
C.
D.
E.
Aplpha-1,4
Alpha-1,6
Beta-1,3
Beta-1,4
Beta-1,6
65. Carbohydrate is stored in the body principally as
A.
B.
C.
D.
E.
glucose.
maltose.
sucrose.
glycogen.
glycosaminoglycans.
67. Which of the following functions as part of the
extracellular matrix?
A.
B.
C.
D.
E.
Mucin
Heparin
Collaginase
Chondroitin sulfate
Dolichol phosphate
69. Glycosaminoglycans function as important
structural components of
A.
B.
C.
D.
glycogen.
nucleic acids.
hyaluronidase.
connective tissue.
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.
64. How many anomeric carbons are present in a
fructose molecule?
A.
B.
C.
D.
E.
0
1
2
5
6
66. Which of the following molecule features
contributes to the water-binding properties of
proteoglycans?
A. The carboxyl groups acting as buffers
B. Central hyaluronate (a helix) trapping water
within
C. 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 Hbonding sites.
68. Each of the following is a glycosaminoglycan
EXCEPT one. Which one is this EXCEPTION?
A.
B.
C.
D.
E.
Chondroitin sulfate
Dermatan sulfate
Hyaluronic acid
Heparan sulfate
Keratin
70. The carbohydrate in highest concentration in
resting muscle is
A.
B.
C.
D.
E.
glucose.
lactose.
sucrose.
glycogen.
inositol.
9
CARBOHYDRATES (Continued)
71. The most biologically important physiochemical
property of connective tissue which is regulated
by its mucopolysaccharide molecules is
A.
B.
C.
D.
viscosity.
buffering capacity.
solubility in dilute acides.
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.
B.
C.
D.
E.
Uracil
Guanine
Thymine
Adenine
Cytosine
74. In the DNA molecule, guanine on 1 strand is
joined to cytosine on the complementary strand
by which of the following bonds?
A.
B.
C.
D.
E.
Amide
1 hydrogen
2 hydrogen
3 hydrogen
Phosphodiester
76. Which of the following are NOT produced by the
hydrolysis of nucleic acids?
A.
B.
C.
D.
E.
Pentoses
Phosphates
Amino acids
Purine bases
Pyrimidine bases
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.
B.
C.
D.
E.
22%
28%
44%
56%
78%
73. Which of the following bonds link the monomeric
units of nucleic acids?
A.
B.
C.
D.
E.
Ionic
Peptide
Thioester
Glycosidic
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 increasing
B. UV light absorption increasing
C. Complementary strands becoming random
coils
D. Base stacking becoming disrupted
E. Hydrogen bond breaking
77. The function of which of the following types of
nucleic acid is to activate and select specific
amino acids for protein synthesis?
A.
B.
C.
D.
E.
rRNA
mRNA
cDNA
tRNA
hnRNA
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.
10
NUCLEIC ACIDS (Continued)
80. Transcription is the cellular process of making
A.
B.
C.
D.
new DNA.
RNA from DNA.
proteins from amino acids by way of RNA.
none of the above.
82. DNA damage by ultraviolet light is due to
A. alkylation of the guanine in DNA.
B. excessive unwinding of the DNA molecule
C. frequent replacement in the DNA molecule
of purines by pyrimidines.
D. induction of dimerization by way of covalent
bonds between adjacent thymine groups.
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
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 composition
B. Can be used to accurately predict its
molecular weight
C. Can be measured by observing the change
in chemical composition
D. Is higher if individual strands of the DNA
double helix are parallel rather than
antiparallel
83. Each of the following is involved in gene cloning
EXCEPT one. Which one is this EXCEPTION?
A.
B.
C.
D.
E.
DNA ligase
RNA polymerase
DNA polymerase I
Restriction nucleases
Reverse transcriptase
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 organism
C. Amplifying a specific DNA sequence
D. Separating polyclonal antibodies
E. Synthesizing RNA and DNA
LIPIDS
86. Which of the following is LEAST descriptive of
lipids?
A.
B.
C.
D.
Nonpolar
Carbon-containing
Amphipathic
Hydrophilic
88. Upon complete hydrogenation, oleic, linoleic and
linolenic acids yield
A.
B.
C.
D.
E.
stearic acid.
myristic acid.
palmitoleic acid.
arachidonic acid.
multiple acetate fragments.
87. Which of the following substances represents an
unsaturated fatty acid?
A.
B.
C.
D.
E.
Cholesterol
Palmitate
Stearate
Choline
Oleate
89. Which of the following classes of steroids
contain 18 carbons and an aromatic ring?
A.
B.
C.
D.
E.
Estrogens
Androgens
Progestagens
Glucocorticoids
Mineralocorticoids
11
LIPIDS (Continued)
90. Gangliosides are glycolipids found on various
cell surfaces. In addition to sphinogosine, their
unit composition contains another characteristic
component. This component is
A.
B.
C.
D.
E.
uronic acid.
plasmalogen.
triglyceride.
N-acetylmuramic acid.
N-acetylneuraminic acid.
92. In addition to phosphoric acid, which of the
following are the products of hydrolysis of
lecithin?
A.
B.
C.
D.
E.
Glycerol, fatty acids, serine
Glycerol, fatty acids, choline
Sphingosine, acetic acid, inositol
Glyceraldehyde, fatty acids, choline
Glyceraldehyde, fatty acids, ethanolamine
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.
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.
91. Neutral fats contain mixtures of one or more fatty
acids esterified with
A.
B.
C.
D.
E.
sterol.
glycerol.
lecithin.
sphinogosine.
alcohols of high molecular weight.
93. Which of the following is an essential fatty acid?
A.
B.
C.
D.
E.
Acetic
Stearic
Myristic
Palmitic
Arachidonic
95. The enzyme catalyzing the rate-controlling step
in the de novo synthesis of fatty acids is
regulated allosterically by the positive modulator
A.
B.
C.
D.
E.
ATP.
NADPH.
Citrate.
cyclic AMP.
oxaloacetate.
97. Beta oxidation of a mole of an 18 carbon fatty
acid under physiologic conditions produces
A.
B.
C.
D.
E.
one mole of acetic acid.
nine moles of acetyl CoA.
nine moles of acetic acid.
one mole of acetoacetic acid.
one mole of hydroxybutyric acid.
12
LIPIDS (Continued)
98. Sodium taurocholate and glycocholate are
necessary for the absorption of
A.
B.
C.
D.
E.
sucrose.
glycerol.
amino acids.
fatty acids.
nucleic acids.
100. Which of the following is MOST often
associated with free fatty acid transport in
human blood?
A.
B.
C.
D.
E.
102.
Albumin
Globulin
Cholesterol
Sphingolipid
Mucopolysaccharide
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.
101. Triglyceride absorbed into the lymphatic
system is transported to the liver as which of
the following?
A.
B.
C.
D.
E.
Very low density lipoprotein
Low density lipoprotein
Chylomicrons
Liposomes
Micelles
Which of the following compounds is an
intermediate in the biosynthesis of
cholesterol?
A.
B.
C.
D.
E.
Squalene
Hexosamine
Cholic acid
Pregnanediol
Deoxycholic acid
MEMBRANES
103. The major lipids that make up the cell
membrane are
A.
B.
C.
D.
E.
triglycerides.
sphingomyelins.
phospholipids.
fatty acids.
steroids.
105. Each of the following lipid classes is
incorporated into membranes EXCEPT one.
Which one is this EXCEPTION?
A.
B.
C.
D.
E.
Cholesterol
Ganglioside
Triglyceride
Sphingomyelin
Phosphatidylcholine
104. The most abundant nonphospholipid
component of the cell membrane is
A.
B.
C.
D.
E.
cholesterol.
deoxycholate.
prostaglandin.
macroglobulin.
triacylglyceride.
106. Which of the following represents a
polyunsaturated fatty acid that is commonly
found in animal cell membranes?
A.
B.
C.
D.
E.
Oleic
Lactic
Sialic
Stearic
Linoleic
13
MEMBRANES (Continued)
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.
109. Which of the following molecules would likely
form a micelle when mixed with water and
agitated?
A.
B.
C.
D.
Serine
Glycerol
Phospholipid
Triglyceride
111. Mediated (facilitated) diffusion of substances
across cell membranes differs from simple
diffusion in that mediated diffusion
A.
B.
C.
D.
requires ATP.
requires another solute.
is a one-directional process.
exhibits saturation kinetics.
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.
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
112. Which of the following features distinguishes
active transport from facilitated diffusion?
A.
B.
C.
D.
Specificity
Carrier-mediated
Requires metabolic energy
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.
B.
C.
D.
Coupling
Allosterism
Modification
Microscopic reversibility
114. A common intermediate of metabolism of
carbohydrates, fatty acids and amino acids is
A.
B.
C.
D.
E.
glycerol.
acetyl CoA.
acetoacetate.
oxaloacetate.
acetylcholine.
14
METABOLISM (Continued)
115. A number of catabolic pathways are
allosterically inhibited by an increase in the
concentration of which of the following?
A.
B.
C.
D.
E.
ADP
AMP
ATP
NAD+
Pyruvate
117. Under strict anaerobic conditions, the
catabolism of one glucose molecule would
yield a net of
A.
B.
C.
D.
2 ATP and 2 lactic acid molecules.
4 ATP and 2 lactic acid molecules.
2 ATP and 2 pyruvic acid molecules.
4 ATP and 2 pyruvic acid molecules.
119. Enzymes that catalyze the anaerobic
processes of carbohydrate metabolism are
found predominantly in which part of a cell?
A.
B.
C.
D.
E.
Cytoplasm
Membrane
Cell wall
Nucleus
Mitochondria
121. Consider the conversion: alanine – lactic acid
– glucose. This is an example of
A.
B.
C.
D.
glycolysis.
glycogenolysis.
gluconeogenesis.
synthesis of glycerol.
116. In the glycolytic sequence, the enzyme that
brings about the transition from 6-carbon
metabolites to 3-carbon metabolites is
A.
B.
C.
D.
E.
phosphoglucoisomerase.
phosphofructokinase.
phosphorylase.
hexokinase.
aldolase.
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.
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.
122. Energy for ATP synthesis is derived from the
electron transport system by which of the
following processes?
A.
B.
C.
D.
E.
Transamination
Aldolization
Reductive synthesis
Oxidative deamination
Oxidative phosphorylation
15
METABOLISM (Continued)
123. The chemical energy generated by
mitochondrial electron transport results from
which of the following?
A. Excess H+ in the matrix
B. An H+ gradient across the inner
membrane
C. The formation of thioesters in the matrix
D. A conformational change in the inner
membrane
125. Which of the following represents the chemical
substance that is the immediate source of
energy for muscle contraction?
A.
B.
C.
D.
E.
Glycogen
Acetyl CoA
Lactic acid
Creatine phosphate
Adenosine triphosphate
127. Enzymes concerned with the citric acid cycle
are found in the
A.
B.
C.
D.
E.
nucleus.
ribosomes.
mitochondria.
nonparticulate cytoplasm.
None of the above
129. If protein is catabolized for energy, then MOST
of the energy is derived from which of the
following?
A.
B.
C.
D.
E.
Urea production
Oxidative deamination
Transamination reactions
Cleavage of peptide bonds
Oxidation of α-keto acids derived from
amino acids.
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.
B.
C.
D.
E.
(1), (3), and (5)
(1) and (4)
(2), (3), and (5)
(2) and (4)
(3) only
126. The tricarboxylic acid cycle is initiated by the
condensation of which of the following two
molecules?
A.
B.
C.
D.
E.
Pyruvate and malate
NAD+ and oxaloacetate
NAD+ and oxalosuccinate
Acetyl coenzyme A and oxaloacetate
Acetyl coenzyme A and oxalosuccinate
128. Acids found in the citric acid (Krebs) cycle are
A.
B.
C.
D.
E.
glutamic acid and succinic acid.
glucuronic acid and aspartic acid.
oxaloacetic acid and aspartic acid.
oxaloacetic acid and pyruvic acid.
oxaloacetic acid and α-ketoglutaric acid.
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
glucuronate
C. Transamination of the alpha amino to a
keto acid
D. Conjugation of the alpha carboxyl group to
glucuronate
E. Decarboxylation of the alpha carboxyl
group to form a primary amine
16
METABOLISM (Continued)
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.
133. What is the product P in the following
reaction?
α-ketoglutarate + alanine = pyruvate + P
A.
B.
C.
D.
E.
Glutamate
Glutamine
Aspartate
Succinate
Pyridoxine phosphate
135. After prolonged acidosis, which of the following
represents the nitrogenous product that is
excreted in high amounts in the urine?
A.
B.
C.
D.
E.
Urea
Ammonia
Uric acid
Creatinine
Aspartic acid
137. In relative insulin insufficiency, acetyl CoA is
usually channeled into
A.
B.
C.
D.
E.
ketone-body formation.
cholesterol synthesis.
fatty-acid synthesis.
gluconeogenesis.
the Krebs cycle
132. The level of nonprotein nitrogen in the blood is
due principally to the level of which of the
following?
A.
B.
C.
D.
E.
Urea
Ammonia
Creatine
Arginine
Uric acid
134. Which of the following tissues is primarily
responsible for formation of urea?
A.
B.
C.
D.
Liver
Brain
Kidney
Muscle
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.
B.
C.
D.
ketosis.
acidosis.
ketonuria.
alkalosis.
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 αketoglutarate.
E. oxidation of L-β-hydroxybutyrate followed
by deacylation.
17
METABOLISM (Continued)
139. The final step in the complete metabolism of
fat is carried out by means of
A.
B.
C.
D.
E.
anaerobic glycolysis.
the tricarboxylic acid cycle.
the reductive fixation of CO2.
the hexose monophosphate shunt.
the Krebs-Henseleit (urea) cycle.
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.
143. The metabolite, 25-hydroxycholecalciferol is
derived MOST immediately from
A.
B.
C.
D.
E.
ergosterol.
cholesterol.
7-dehydro-sitosterol.
7-dehydro-cholesterol.
22-dihydro-ergosterol.
145. Most endogenous cholesterol in the liver is
usually converted into which of the following?
A.
B.
C.
D.
E.
Glucose
Steroids
Cholic acid
Oxaloacetate
Ketone bodies
147. Purine ribonucleoside phosphates are all
synthesized de novo from the common
intermediate
A.
B.
C.
D.
E.
inosine phosphate.
guanosine phosphate.
adenosine phosphate.
guanosine diphosphate.
deoxyadenosine phosphate.
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.
142. Prostaglandins are made within cells
A.
B.
C.
D.
E.
on an RNA template.
on rough endoplasmic reticulum.
from methionine.
from progesterone.
from polyunsaturated fatty acids.
144. Which of the following is necessary for de
novo synthesis of cholesterol?
A.
B.
C.
D.
E.
NAD+
NADH
NADP+
NADPH
FADH2
146. Ribose phosphate needed for nucleic acid
synthesis can be derived from
A.
B.
C.
D.
E.
gluconeogenesis.
the pentose phosphate pathway.
the Krebs’ tricarboxylic acid cycle.
decarboxylation of aromatic amino acids.
one-carbon transfer from tetrahydrofolate
derivatives.
148. Which of the following enzymes catalyzes the
formation of uric acid from purines?
A.
B.
C.
D.
E.
Urease
Uricase
Xanthine oxidase
Aspartate transcarbamoylase
Carbamoyl-phosphate synthetase
18
METABOLISM (Continued)
149. Which of the following is a source of
transferable methyl groups in metabolism?
A.
B.
C.
D.
Valine
Choline
Leucine
Isoleucine
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.
B.
C.
D.
E.
Polysaccharides
Acylglycerols
Gangliosides
Fatty acids
Proteins
150. Coenzyme A participates in
A.
B.
C.
D.
formylation.
protein synthesis.
methionine activation.
activation of carboxyl groups.
152. Glucosuria with hyperglycemia usually occurs
in which of the following?
A.
B.
C.
D.
E.
Pellagra
Addison’s disease
Diabetes mellitus
Diabetes insipidus
Parkinson’s disease
VITAMINS
153. Which of the following is a vitamin?
A.
B.
C.
D.
E.
Adenine
Inosine
Xanthine
Thyroxin
Pyridoxine
155. Pantothenic acid is an integral part of
A.
B.
C.
D.
E.
NAD+.
cobalamin.
folic acid.
coenzyme A.
pyridoxine phosphate.
157. A vitamin derivative concerned with conversion
of glucose to lactic acid is
A.
B.
C.
D.
thiamine (as cocarboxylase).
pantothenic acid (as coenzyme A).
pyridoxal (as pyridoxal phosphate).
nicotinamide (as nicotinamide adenine
dinucleotide).
154. The general reaction for the transfer of a “onecarbon fragment” requires the coenzyme
A.
B.
C.
D.
E.
pyridoxal phosphate.
tetrahydrofolic acid.
thiamine pyrophosphate.
flavin adenine dinucleotide.
diphosphopyridine nucleotide.
156. Derivatives of riboflavin and niacin function as
A.
B.
C.
D.
CO2 acceptors
coenzymes in redox reactions.
factors in transamination reactions.
replacements for each other in biologic
reactions.
158. Which of the following vitamins is necessary
as a coenzyme in the initial steps of fatty acid
synthesis?
A.
B.
C.
D.
E.
Biotin
Thiamine
Vitamin A
Vitamin D
Riboflavin
19
VITAMINS (Continued)
159. Which of the following is required for vitamin
D3 synthesis?
A.
B.
C.
D.
Decarboxylation in the liver
UV activation of precursors in skin
Metabolism by gut bacteria
Deamination in the kidney
161. Vitamin A functions to
A.
B.
C.
D.
prevent pellagra.
promote absorption of calcium.
promote differentiation of epithelial cells.
maintain the integrity of connective
tissues.
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.
165. Which of the following is NOT involved as a
cofactor in formation of acetyl CoA from
pyruvate?
A.
B.
C.
D.
E.
NAD+
FAD
Pyridoxine
Lipoic acid
Thiamine pyrophosphate
160. Hydroxylation at the 1 position of 25hydroxycholecalciferol occurs primarily in the
A.
B.
C.
D.
skin.
liver.
kidney.
intestinal mucosa.
162. A deficiency of vitamin A in a developing tooth
most likely affects the
A.
B.
C.
D.
pulp.
enamel.
dentin.
cementum.
164. Which of the following is a function of vitamin
B6 (pyrodoxal phosphate)?
A. Prevents pernicious anemia
B. Allows adaptation to dim light
C. Acts as coenzyme in transamination
reaction
D. Prevents microcytic hypochromic anemia
166. A derivative of vitamin K is the coenzyme for
which of the following?
A.
B.
C.
D.
E.
Production of menadiol
Esterfication of retinol
Hydrolysis of peptide bonds
Cross-linking of fibrinogen
Carboxylation of glutamate side chains
20
VITAMINS (Continued)
167. The function of vitamin K is involved directly
with
A.
B.
C.
D.
E.
synthesis of prothrombin.
activation of the Stuart factor.
regulation of calcium in the blood.
conversion of fibrinogen to fibrin.
transcriptional control for fibrinogen
synthesis.
169. Osteoblasts form the organic matrix of bone
prior to calcification of the tissue. This process
requires vitamins
A.
B.
C.
D.
E.
A and B12.
A and C.
A and D.
C and E.
D and E.
168. Which of the following vitamins can be
supplied to humans by the normal action of
intestinal flora?
A.
B.
C.
D.
E.
A
D
E
K
None of the above
170. To which of the following avitaminoses is the
gingival most susceptible?
A.
B.
C.
D.
E.
A
B2
B6
C
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.
B.
C.
D.
nucleic acids.
carbon dioxide.
metabolism of carbohydrates.
methylene folic acid derivatives.
173. Which of the following groups includes only
amino acids essential for humans?
A.
B.
C.
D.
E.
Valine, serine, leucine
Leucine, lysine, glycine
Tyrosine, threonine, tryptophan
Phenylalanine, methionine, proline
Tryptophan, methionine, isoleucine
175. A diet rich in tryptophan offsets a deficiency of
which of the following vitamins?
A.
B.
C.
D.
Niacin
Thiamine
Riboflavin
None of the above
172. Negative nitrogen balance (nitrogen excretion
> intake) may be cause by
A.
B.
C.
D.
growth.
protein synthesis.
dietary lack of essential amino acid.
synthesis and catabolism of equal
amounts of body protein.
174. Which of the following amino acids lessens the
need for phenylalanine?
A.
B.
C.
D.
E.
Lysine
Leucine
Glycine
Tyrosine
Tryptophan
176. A deficiency of rhodopsin is most likely caused
by decreased dietary intake of
A.
B.
C.
D.
E.
glucose.
adenine.
vitamin A.
tryptophan.
riboflavin.
21
NUTRITION (Continued)
177. Lipid is required in the average diet because it
A.
B.
C.
D.
has a high caloric value.
provides essential fatty acids.
aids in absorption of carbohydrates.
is necessary for storage of carbohydrates.
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.
181. Which of the following represents the amount
of dietary calcium normally absorbed from the
gut of an adult man?
A.
B.
C.
D.
An amount less than 50%
An amount between 60-70%
An amount between 80-100%
An amount dependent up the mucosal
ferritin level
183. The recommended daily dietary allowances for
Ca and P provide a Ca/P intake of
approximately
A.
B.
C.
D.
E.
0.5.
1.0
2.0.
3.0.
4.0.
185. Which of the following is secreted more during
the absorptive state than during the
postabsorptive state?
A.
B.
C.
D.
E.
Insulin
Glucagon
Cortisol
Thyroxine
Ephinephrine
178. A deficiency of choline in the diet can cause
abnormalities in the metabolism of
A.
B.
C.
D.
E.
lipids.
proteins.
minerals.
carbohydrates.
nucleoproteins.
180. Which of the following minerals are most
frequently in short supply in American diet?
A.
B.
C.
D.
Calcium and iron
Calcium and iodine
Sulfur and potassium
Iodine, magnesium and iron
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.
184. Which of the following must be digested before
being in a form that can be absorbed by
enterocytes?
A.
B.
C.
D.
E.
Monoglycerides
Fatty acids
Fructose
Glycine
Maltose
186. A sustained, severe carbohydrate deficiency in
the diet will result in which of the following?
A.
B.
C.
D.
Ketoacidosis
Severe metabolic alkalosis
A deficiency in prostaglandin formation
An inability to synthesize ascorbic acid
22
HORMONES
187. Which of the following hormones is a
polypeptide?
A.
B.
C.
D.
E.
Epinephrine
Testosterone
Progesterone
Triiodotyronine
Follicle-stimulating hormone
189. Which of the following hormones is NOT
synthesized from cholesterol?
A.
B.
C.
D.
E.
Progesterone
Testosterone
Estradiol
Cortisol
Relaxin
191. Each of the following characterizes a peptide
hormone EXCEPT one. Which one is this
EXCEPTION?
A.
B.
C.
D.
E.
Stored in secretory granules
Synthesized in a precursor form
Binds to intracellular receptors
Acts by generating a second messenger
Usually transported unbound in plasma
193. The intracellular, “second” messenger for
many peptide and polypeptide hormones is
A.
B.
C.
D.
E.
AMP.
ATP.
cyclic AMP.
adenylate cyclase.
a cytoplasmic receptor.
195. The hyperglycemic effect of glucagon is
mediated primarily through
A.
B.
C.
D.
E.
the growth hormone.
muscle glycolysis.
liver glycogenolysis.
inhibition of cortisol action.
enhanced glucose reabsorption by renal
tubules.
197. Which of the following takes place as
proinsulin is converted to insulin?
A.
B.
C.
D.
Disulfide bonds are formed.
Disulfide bonds are broken.
The polypeptide chain is lengthened.
A segment of the polypeptide chain is
removed.
188. Iodine is primarily important in the biochemical
synthesis of
A.
B.
C.
D.
E.
ACTH.
thyroxin.
adrenalin.
calcitonin.
parathyroid hormone.
190. In which of the following combinations is the
name of the hormone, its chemical type and its
tissue of origin correctly matched?
A.
B.
C.
D.
E.
Aldosterone-peptide-pancreas
Glucagon-peptide-adrenal cortex
Epinephrine-steroid-adrenal medulla
ACTH-polypeptide-adrenal cortex
Vasopressin-peptide-posterior pituitary
192. Which of the following generates a slowly
developing long-term response in target
tissues by binding to an intracellular receptor?
A.
B.
C.
D.
E.
Glucagon
Estrogen
Prolactin
Growth hormone
Parathyroid hormone
194. Epinephrine causes an elevation in cAMP
levels in muscle cells which in turn activate
A.
B.
C.
D.
E.
ATPase.
adenyl cyclase.
glycogen synthetase.
glycogen phosphorylase.
glycogen phosphorylase phosphatase.
196. Two hormones which act similarly to increase
glycogen and lipid breakdown as well as cyclic
AMP synthesis are
A.
B.
C.
D.
insulin and calcitonin.
glucagon and epinephrine.
aldosterone and testosterone.
parathyroid hormone and glucagon.
198. Which of the following hormones does NOT
induce activation of adenylate cyclase?
A.
B.
C.
D.
Insulin
Glucagon
Epinephrine
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.
B.
C.
D.
E.
insulin.
cortisol.
glucagons.
epinephrine.
testosterone.
201. Aldosterone is normally associated with partial
regulation of which of the following processes?
A.
B.
C.
D.
E.
Sodium balance
Gluconeogenesis
Lipid digestion
Protein degradation
Carbohydrate metabolism
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
205. Hyperparathyroidism is marked by
A.
B.
C.
D.
E.
chronic tetany.
a high blood calcium level.
retention of phosphates by the kidneys.
storage of excess minerals in the bones.
increased irritability of excitable tissues.
200. Which of the following is a principal action of
insulin?
A.
B.
C.
D.
To mobilize lipid deposits
To enhance cell permeability to glucose
To decrease cell permeability to glucose
To conserve glucose by breaking down
amino acids
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.
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 bone
C. Stimulation of calcium reabsorption by
kidney
D. Inhibition of phosphate reabsorption by
kidney
E. Inhibition of intestinal absorption of
calcium
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.
24
HORMONES (Continued)
207. A parathyroidectomized animal will exhibit
which levels of calcium and phosphate ion
concentration in the plasma?
Calcium
A.
B.
C.
D.
E.
Phosphate ion
concentration
Low
Normal
High
Normal
Low
High
Low
Low
Normal
Low
209. Hydrolysis of thyroglobulin liberates a number
of iodinated compounds. Two are considered
thyroid hormones. These are
A.
B.
C.
D.
tyrosine and thyronine.
tyrosine and diiodotyrosine.
thyroxin and triiodothyronine.
thyroxin and triiodotyrosine.
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.
213. The gallbladder is caused to contract by the
hormone
A.
B.
C.
D.
E.
gastrin.
secretin.
pancreozymin.
enterogastrone.
cholecystokinin.
208. Which of the following are the immediate
effects of calcitonin on serum levels of calcium
and phosphate?
Serum calcium
A.
B.
C.
D.
E.
Increased
Increased
Decreased
No change
Decreased
Serum phosphate
Increased
Decreased
Decreased
Increased
No change
210. Thyroid hormones, glucocorticoids and
gonadal steroids are similar in that each
A.
B.
C.
D.
is derived from cholesterol.
is derived from amino acids.
acts on only one target organ or tissue.
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.
212. The physiologically active form of vitamin D
produced in the kidney is
A.
B.
C.
D.
E.
1,25-dihydroxycholecalciferol.
25-hydroxycholecalciferol.
7-dehydrocholesterol.
cholecalciferol.
ergosterol.
214. Secretin functions in digestion of proteins by
increasing
A.
B.
C.
D.
flow of bile.
secretion of pepsin.
flow of pancreatic juice.
secretion of carboxypeptidase.
215. Androgens are produced in the testis and
A.
B.
C.
D.
E.
adrenal cortex.
thyroid.
adrenal medulla.
pituitary.
hypothalamus.
25
FLUORIDE
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.
218. Which of the following statements is NOT true
concerning fluoride?
A.
B.
C.
D.
It is expected rapidly by the kidney.
It is deposited in calcified tissues.
It occurs only in the ionic form in plasma.
It passes the placental barrier relatively
slowly.
E. At 1 ppm. In water, it is tasteless, odorless
and colorless.
220. The rate of fluoride incorporation into bone
depends upon the
A.
B.
C.
D.
E.
water-mineral ratio.
age of the individual.
rate of bone remodeling or turnover.
amount of ionizable fluoride in the diet.
All of the above
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.
219. The anticaries effect of fluoride is LEAST
related to which of the following?
A.
B.
C.
D.
E.
Ion exchange
Decreased solubility
Facilitation of remineralization
Its presence during enamel formation
Activation of plaque polysaccharide
hydrolysis
221. Sodium fluoride inhibits glycolysis by affecting
which of the following?
A.
B.
C.
D.
Amylase
Enolase
Phosphatase
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.
26
BLOOD CLOTTING (Continued)
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.
226. Which of the following represents the normal
substrate of thrombin?
A.
B.
C.
D.
E.
Fibrin
Thrombospondin
Prothrombin
Thromboplastin
Fibrinogen
225. Which of the following compounds is NOT
involved in coagulation of blood?
A.
B.
C.
D.
E.
Fe+2
Ca+2
Prothrombin
Fibrinogen
Thromboplastin
227. Which of the following ions is involved in blood
clotting?
A.
B.
C.
D.
Iron
Sodium
Calcium
Potassium
BONES AND TEETH
228. The organic matrix of bone is composed
largely of collagen and
A.
B.
C.
D.
lipids.
citrate.
dextrans.
glycosaminoglycans.
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.
232. Which of the following noncollagenous protein
components BEST characterizes dentin
matrix?
A.
B.
C.
D.
E.
Laminin
Vimentin
Phosphophoryn
Osteonectin
Fibronectin
229. Which of the following represent(s) the matrix
proteins of enamel?
A.
B.
C.
D.
E.
Carboxylglutamic acid containing proteins
Type I collagen
Amelogenins
Proteoglycans
Elastin
231. Which of following is the major protein
component of cementum?
A.
B.
C.
D.
E.
Elastin
Keratin
Collagen
Amelogenin
Osteonectin
233. Which of the following has a high affinity for
binding calcium and collagen in the calcifying
matrix?
A.
B.
C.
D.
E.
Calcitonin
Osteogenin
Osteonectin
Amelogenin
Fibronectin
27
BONES AND TEETH (Continued)
234. Protein content of enamel from mature teeth is
approximately what per cent of enamel
weight?
A.
B.
C.
D.
E.
0.1-1%
5-10%
15-20%
25-30%
50-55%
236. Which of the following BEST characterizes
hydroxyapatite?
A. Has an amphiphilic surface
B. Contains 12 ions per unit cell
C. As found in bone and enamel contains no
ion substitutions
D. Has a higher solubility product constant
than fluoroapatite
238. Which of the following vitamins is the LEAST
likely to be involved in tooth development and
calcification?
A.
B.
C.
D.
A
B1
C
D
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.
242. The extracellular polysaccharides synthesized
by cariogenic streptococci in the presence of
excess sucrose are best described as
A.
B.
C.
D.
E.
amylase.
amylopectin.
mucopolysaccharide.
glycogen-like glucan.
dextran-like glucan.
235. Which of the following functions of bone could
be considered the most prominent?
A.
B.
C.
D.
E.
Buffering
Phosphate source
Sodium reservoir
Fluoride reservoir
Calcium reservoir
237. The lack of which of the following substances
during tooth formation most likely induces
enamel hypoplasia?
A.
B.
C.
D.
E.
Vitamins A and D
Vitamins C and D
Vitamins C and K
Phosphorus and iron
Calcium and fluoride
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.
241. Which of the following sweeteners is nonnutritive as well as non-cariogenic?
A.
B.
C.
D.
E.
D-fructose
Saccharin
Galactose
Sorbitol
Maltose
243. Which of the following represents a soluble
polysaccharide found in dental plaque and is
formed from the fructose moiety of sucrose?
A.
B.
C.
D.
Levan
Dextran
Amylopectin
Hyaluronic acid
28
BIOCHEMISTRY NATIONAL BOARD EXAM REVIEW
ANSWERS and COMMENTARY
BASIC CHEMISTRY
There are usually 1-2 basic chemistry questions.
1.
2.
3.
4.
5.
6.
7.
D
A
B
B
B
D
A
Same question in 1987 and 1998.
Same question in 1985 and 1998.
BUFFERS AND pH
8.
C
9.
10.
11.
12.
13.
C
B
D
A
C
A question on the Henderson-Hasselbalch question appeared on exams in 1978,
1982, 1985, and 1998. Know this fundamental equation.
Same question in 1989 and 1996.
Very similar question in 1996 and 1998.
Be familiar with physiologic buffers.
BICARBONATE/CO2
There are usually 1-2 questions covering carbonic acid, bicarbonate and CO2.
14.
15.
16.
17.
18.
D
B
E
D
A
Same question in 1978, 1981, 1985, and 1987.
Very similar question in 1978, 1979, 1981 and 1996.
A good question on this physiologic buffer system.
A variation of this 1998 question on carbonic anhydrase appeared on the 1987
exam.
PROTEINS
19.
C
20.
21.
22.
23.
24.
B
B
C
C
E
25.
B
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)
Same question in 1978, 1989, and 1996.
Similar questions about types of proteins, as indicated by the choice of answers,
have appeared on several exams.
A question on pI, pH and electrophoresis of a protein or peptide is common.
ENZYMES
26.
27.
28.
29.
30.
E
B
C
B
A
Same question in 1981, 1985, and 1987; and a similar question in 1996.
Know the definition of the kinetic parameters, Km and Vmax.
Know the characteristics of competitive, non-competitive, uncompetitive and
mixed inhibition.
29
31.
D
32.
33.
34.
35.
36.
37.
38.
39.
A
D
B
A
D
C
B
A
Regulation of enzyme activity by phosphorylation is a common question, often in
terms of specific enzymes.
Know characteristics of allosteric modifiers.
There is frequently a question on enolase because it is inhibited by fluoride.
Know the common zymogens and how they are activated.
COLLAGEN
40.
41.
42.
43.
44.
45.
D
B
C
A
D
E
Know all aspects of collagen.
Questions on post-translational modifications of collagen are very common.
HEMOGLOBIN
46.
47.
48.
49.
D
C
D
A
50.
51.
E
A
Know the effects of pH, CO2, and 2,3-bisphosphoglycerate on binding of O2 to
hemoglobin.
A question related to sickle cell anemia occurs frequently.
PROTEIN SYNTHESIS
52.
53.
54.
55.
56.
57.
58.
C
A
C
A
C
B
E
CARBOHYDRATES
59.
60.
61.
62.
63.
64.
65.
66.
67.
C
D
A
A
B
B
D
D
D
68.
69.
70.
71.
E
D
D
A
A question on sucrose is almost inevitable.
A question on configuration is common.
Generally there are 2-3 questions on amino sugar compounds and
glycoaminoglycans. (Next two questions for example.)
30
NUCLEIC ACIDS
The number of questions on nucleic acids and molecular biology have increased in recent years.
72.
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
84.
85.
A
E
D
A
C
D
B
C
B
A
D
B
C
C
Know base pairing.
LIPIDS
Generally, lipids are emphasized: different classes of lipids, reactions, metabolism, and functions.
86.
87.
88.
89.
90.
91.
92.
93.
94.
D
E
A
A
E
B
B
E
C
95.
96.
97.
98.
99.
100.
101.
102.
C
A
B
D
D
A
C
A
Same question on exams in 1985 and 1987.
The same or similar question was on exams in 1979, 1987, and 1996.
Same question on exams in 1985, 1987, and 1989. Know fatty acid synthesis
and degradation ( -oxidation). See the following questions.
There is usually 1-2 questions on the composition and function of bile salts.
The same or similar question appeared on at least 4 exams.
Know what the different classes of serum lipoproteins transport and to where.
MEMBRANES
Questions on membranes tend to focus on composition and transport.
103.
104.
105.
106.
107.
108.
109.
110.
111.
112.
C
A
C
E
C
B
C
B
D
C
31
METABOLISM
Carbohydrate, amino acid, lipid, and nucleotide metabolism are included.
113.
114.
115.
116.
117.
118.
119.
120.
121.
122.
A
B
C
E
A
E
A
A
C
E
123.
124.
125.
126.
127.
128.
129.
130.
131.
132.
133.
134.
135.
136.
B
D
E
D
C
E
E
C
B
A
A
A
B
D
137.
138.
139.
140.
141.
142.
143.
144.
145.
146.
147.
148.
149.
150.
151.
152.
A
C
B
E
B
E
D
D
C
B
A
C
B
D
C
C
A similar question has been on at least four exams.
At least 1 question on electron transport and oxidative phosphorylation is
common. See following question.
A good question.
The identical question or a similar one has appeared on at least 5 exams.
A good question that covers several aspects of amino acid metabolism.
At least one question on ketogenesis, ketosis, or ketone bodies is common. See
following two questions.
Know cholesterol metabolism.
VITAMINS
There is usually several questions on vitamins because of their involvement in many biological processes.
153.
154.
155.
156.
157.
158.
159.
160.
161.
E
B
D
B
D
A
B
C
C
A question on vitamin D is common.
32
162.
163.
164.
165.
166.
167.
168.
169.
170.
B
C
C
C
E
A
D
B
D
A similar question has appeared on at least 3 exams.
Know vitamin K. See following 2 questions.
NUTRITION
Nutrition 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
172.
173.
174.
175.
176.
177.
178.
179.
180.
181.
182.
183.
184.
185.
186.
C
E
D
A
C
B
A
B
A
A
D
B
E
A
A
Esential amino acids and related metabolism tend to be emphasized. See
following 4 questions.
Know calcium.
HORMONES
Questions cover the chemical composition, biosynthesis, mechanism of action, and physiological functions of
hormones.
187.
188.
189.
190.
E
B
E
E
191.
192.
193.
194.
C
B
C
D
195.
196.
197.
198.
199.
200.
201.
202.
C
B
D
A
A
B
A
B
A good question because it covers different characteristics of a particular
hormone.
Know the hyperglycemic (epinephrine, glucagon) and hypoglycemic (insulin)
hormones. See the following 6 questions.
A question on aldosterone has appeared on at least 5 exams.
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
204.
205.
206.
207.
208.
209.
210.
211.
212.
213.
214.
215.
E
B
A
A
C
C
D
A
A
E
C
A
Questions on parathyroid hormone and calcitonin and their regulation of calcium
and phosphate levels are emphasized. See the following 5 questions.
FLUORIDE
216.
217.
218.
219.
220.
221.
E
A
C
E
E
B
This same question has appeared on at least 4 exams.
BLOOD CLOTTING
222.
223.
224.
225.
226.
227.
A
B
B
A
E
C
BONES and TEETH
The composition and properties of bones and teeth, the effects of hormones and vitamins, and caries are
emphasized.
228.
229.
230.
231.
232.
233.
234.
235.
236.
237.
238.
239.
240.
241.
242.
243.
D
C
A
C
C
C
A
E
D
A
B
B
B
B
E
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.
B.
C.
D.
not move.
move to the anode.
move to the cathode.
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.
B.
C.
D.
E.
A4.
Pepsin
Amylase
Hexokinase
Adenylate cyclase
Carbonic anhydrase
Which of the following is an allosteric effector
of an enzymatic reaction?
A.
B.
C.
D.
Competitive inhibitor
Noncompetitive inhibitor
Substance that binds to the substrate
Substance affecting enzymatic activity by
binding to the active site
E. Substance affecting enzymatic activity by
binding to non-active sites
Lysine and arginine
Arginine and leucine
Leucine and valine
Valine and glutamic acid
Glutamic acid and lysine
Zinc is an essential component of which of the
following?
A.
B.
C.
D.
E.
A3.
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 histidines
C. Decreased solubility of the deoxy form of
hemoglobin
D. 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.
B.
C.
D.
E.
A8.
valine, threonine, and lysine.
desmosine, glycine, and proline.
cysteine, tyrosine, and phenylalanine.
glycine, proline, and hydroxyproline.
cysteine, hydroxylysine, and proline.
Which of the following vitamins is essential for
the normal elaboration and maintenance of
bone matrix, cartilage, and dentin?
A.
B.
C.
D.
Niacin
Vitamin E
Ascorbic acid
Pantothenic acid
A7. Which of the following is MOST likely to
promote depolymerization of extracellular
matrix?
A.
B.
C.
D.
Cortisone
Collagenase
Chymotrypsin
Hyaluronidase
A9. Which of the following statements BEST
describes hydroxyapatite in enamel?
A.
B.
C.
D.
E.
Has a nonpolar surface
Has 10 ions in each unit cell
Contains no ion substitutions
Has a higher solubility than fluorapatite
Has a solubility that decreases as the pH
decreases
CARBOHYDRATES
A10. What are predominant linkages in glycogen
between glucose units?
A.
B.
C.
D.
E.
Alpha-1,4
Alpha-1,6
Beta-1,3
Beta-1,4
Beta-1,6
A12. Which of the following is the pathway that
results in the formation of glucose in the liver
from lactate produced in muscle?
A.
B.
C.
D.
Cori cycle
Glycolysis
Citric acid cycle
Pentose phosphate pathway
A11. Glucose can be made from each of the
following substances EXCEPT one. Which
one is this EXCEPTION?
A.
B.
C.
D.
E.
Lactate
Acetyl CoA
Glycerol
Pyruvate
Fructose
A13. Which of the following mechanisms operates in
liver cells to regulate breakdown of glycogen?
A. Zymogen activation
B. Phosphorylation of phosphorylase b to
phosphorylase a
C. Induction of phosphorylase b by an
inducer
D. Inhibition of adenylate cyclase
A14. Glucose-6-phosphatase is found associated
with which of the following?
A.
B.
C.
D.
Kidneys and liver
Liver and muscles
Kidneys and brain
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.
B.
C.
D.
E.
G-C
A-T
G-U
C-T
A-U
A17. DNA that is complementary to mRNA can be
made using which of the following?
A.
B.
C.
D.
E.
A plasmid
DNA ligase
A retrovirus
RNA polymerase
Reverse transcriptase
A19. Which of the following enzymes seals nicks in
DNA?
A.
B.
C.
D.
E.
Exonuclease
Endonuclease
Ligase
DNA polymerase
RNA polymerase
A21. Which of the following BEST describes
restriction enzymes?
A.
B.
C.
D.
E.
Exonucleases
Topiosomerases
Enzymes that degrade RNA
Non-specific endonucleases
Site-specific endonucleases
A23. Which of the following enzymes synthesizes
polynucleotide chains from nucleotides and
does NOT require a primer chain?
A.
B.
C.
D.
E.
Ligase
Exonuclease
Endonuclease
DNA polymerase
RNA polymerase
A16. If the anticodon on transfer-RNA is 5’ACG3’,
then which of the following is its corresponding
codon on messenger-RNA?
A.
B.
C.
D.
E.
5’ CGT 3’
5’ CGU 3’
5’ TGC 3’
5’ UAG 3’
5’ UGC 3’
A18. Which of the following represents the
consequence of the fact that DNA strands are
complementary?
A.
B.
C.
D.
Hairpin loop structures can be generated
They will always have identical sequences
Separated strands are able to reassociate
They cannot get back together once
separated
A20. Which of the following BEST describes the
major function of histones?
A.
B.
C.
D.
E.
Unwind DNA.
Activate genes.
Stabilize DNA in a compact form.
Remove exons during RNA splicing.
Stabilize RNA during transcription.
A22. Which of the following types of blotting can be
used to identify DNA restriction fragments?
A.
B.
C.
D.
Eastern
Southern
Northern
Western
A24. Which of the following is produced when a
mutation occurs in an enzyme controlling a
signal pathway involved in cell growth
processes?
A.
B.
C.
D.
E.
Epigene
Antigene
Oncogene
Monogene
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.
B.
C.
D.
E.
thiolase.
pyruvate carboxylase.
citrate synthetase.
acetyl CoA carboxylase.
pyruvate dehydrogenase.
A27. Which of the following is a ketone body?
A.
B.
C.
D.
E.
Glycerol
Glucagon
Acetyl CoA
Acetoacetate
Phosphatidycholine
A26. Each of the following is expected to be active
during fatty acid biosynthesis EXCEPT one.
Which one is this EXCEPTION?
A.
B.
C.
D.
E.
Tricarboxylic acid cycle
Pyruvate dehydrogenase
Amino acid catabolism
Beta oxidation
Glycolysis
A28. Bile salts are sodium salts of bile acid that are
conjugated with
A.
B.
C.
D.
cysteine and serine.
taurine and glycine
methionine and lysine.
homocysteine and ornithine.
MEMBRANES/TRANSPORT
A29. Facilitated diffusion DIFFERS from active
transport in that net transport by facilitated
diffusion
A.
B.
C.
D.
has a transport maximum.
uses ATP as an energy source.
requires a concentration gradient.
occurs as an endergonic (positive ΔG)
process.
A31. Active transport systems generally involve
specific binding molecules that are classified
as a
A.
B.
C.
D.
E.
lipid.
protein.
lipoprotein.
carbohydrate.
phospholipid.
A30. The cell membrane is LEAST permeable to
which of the following substances?
A.
B.
C.
D.
E.
O2
CO2
H2O
Sodium
Ethanol
A32. Which of the following provides the immediate
energy source for the transport of glucose into
intestinal epithelial cells?
A.
B.
C.
D.
NADH
NADPH
Na+ gradient across the luminal
membrane
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.
B.
C.
D.
Amino acids
Fatty acids
Carbohydrates
Proteins
A35. Which of the following directly catalyzes urea
formation in a cell?
A.
B.
C.
D.
Urease
Uricase
Arginase
Glutaminase
A34. The catabolism of which of the following results
in no energy production in the form of ATP?
A.
B.
C.
D.
Lipid
Protein
Nucleotide
Carbohydrate
A36. Which main product of protein nitrogen
metabolism is found in human urine?
A.
B.
C.
D.
E.
Urea
Ammonia
Creatine
Uric acid
Creatinine
A37. Which of the following compound is a
precursor of the pigments of the skin, hair, and
eyes?
A.
B.
C.
D.
E.
Tyrosine
Cysteine
Lysine
Creatine
Galactosamine
HORMONES
A38. Which of the following promotes the release of
bile from the gallbladder?
A.
B.
C.
D.
E.
Gastrin
Secretin
Galla
Bombesin
Cholecystokinin
A40. Which of the following hormones exerts the
LEAST effect on calcium metabolism of bone
tissues?
A.
B.
C.
D.
E.
Androgen
Estrogen
Norepinephrine
Thyroid hormone
Parathyroid hormone
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.
A41. The biologically active conformation of trimeric
G-proteins requires
A.
B.
C.
D.
the alpha-subunit to bind GDP.
the alpha-subunit to bind GTP.
the hydrolysis of BetaGamma-subunits.
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.
B.
C.
D.
NAD
Biotin
Coenzyme A
Thiamine pyrophosphate
Testlet 1.
A 23-year-old female present with complaints
of difficulty in opening her mouth and a lowgrade 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.
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.
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.
B.
C.
D.
E.
Coma
Dizziness
Confusion
Convulsion
Hyperventilation
A43. Which of the following coenzymes is required
for the synthesis of pyrimidines, such as
thymine?
A.
B.
C.
D.
E.
Niacin
Thiamine
Folic acid
Riboflavin
Pyridoxine
A44. Rifampin (Rifadin®) is effective in treating
active tuberculosis because it targets which of
the following pathways?
A.
B.
C.
D.
E.
Mitosis
Replication
Translation
Transcription
mRNA splicing
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.
A47. Which of the following glucose transporters
was responsible for the patient’s “insulin
reaction”?
A.
B.
C.
D.
E.
GLUT-1
GLUT-2
GLUT-3
GLUT-4
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.
B.
C.
D.
E.
Insulin
Estrogen
Aldosterone
Thyroid stimulating hormone
Parathyroid hormone
A49. Administration of a local anesthetic with
epinephrine will MOST likely produce which of
the following cardiovascular effects?
A.
B.
C.
D.
Increased heart rate
Decreased heart rate
Increased diastolic blood pressure
Decreased systolic blood pressure
41
Answers for Addendum, June, 2005
A1.
A2.
A3.
A4.
A5.
A6.
A7.
A8.
A9.
A10.
A11.
A12.
A13.
A14.
A15.
A16.
A17.
A18.
A19.
A20.
A21.
A22.
A23.
A24.
A25.
A
C
E
E
C
D
D
C
D
A
B
A
B
A
B
B
E
C
C
C
E
B
E
C
D
A26.
A27.
A28.
A29.
A30.
A31.
A32.
A33.
A34.
A35.
A36.
A37.
A38.
A39.
A40.
A41.
A42.
A43.
A44.
A45.
A46.
A47.
A48.
A49.
D
D
B
C
D
B
C
B
C
C
A
A
E
B
C
B
B
C
D
C
E
D
E
A
42