Biokem PRC Questions
Biokem PRC Questions
Biokem PRC Questions
16. Sickle cell anemia is the manifestation of homozygous genes for an abnormal
hemoglobin molecule. The mutation in the beta-chain is known to produce a
single amino acid change. The most likely mechanism for this mutation is:
A.
Two base insertion
B.
Three base deletion
C.
Nondysjunction
D.
Point mutation
Ans. D
Ref: Harpers Biochemistry 24th ed. p. 734
MPL: 0.75
17. A culture of bacteria not resistant to Tetracycline develops an infection from a
virus that is derived from the lysis of tetracycline-resistant bacteria. Most of the
bacterial progeny of the original culture is found to have become resistant to
tetracycline. What phenomenon has occurred?
A.
Conjugation
B.
Recombination
C.
Transformation
D.
Transduction
Ans. D
Ref: Harpers Biochemistry 24th ed. p. 471
MPL: 0.75
18. Following ultraviolet damage to DNA in the skin, which of the following is MOST
likely to occur?
A.
A specific nuclease detects damaged areas.
B.
Purine dimmers are formed.
C.
Both strands are cleaved.
D.
Endonuclease removes the damaged strand.
Ans. A
Ref: Harpers Biochemistry 24th ed. p. 814
MPL: 0.75
19. Which of the following statements about the genetic code is the MOST accurate?
A.
Information is stored as sets of dinucleotide repeats called codons.
B.
The code is degenerate.
C.
There are 64 codons, all of which code for amino acids.
D.
Information is stored as sets of trinucleotide repeats called codons.
Ans. B
Ref: Harpers Biochemistry 24th ed. p. 433-434
MPL: 0.75
20. Which of the following is provided by the Northern Blot Analysis?
A.
Detection of specific base pairs.
B.
Detection of DNA molecules.
C.
Detection of RNA molecules.
D.
Detection of proteins.
Ans. C
Ref: Harpers Biochemistry 24th ed. p. 472-473
MPL: 1.0
21. In contrast to DNA polymerase, RNA polymerase:
A.
Fills in the gap between the Okazaki fragments.
B.
Works only in a 5 to 3 direction.
C.
Edits as it synthesizes.
D.
Synthesizes RNA primer to initiate DNA synthesis.
Ans. D
Ref: Harpers Biochemistry 24th ed. p. 418
MPL: 0.75
22. The removal of introns and subsequent self-splicing of adjacent exons occurs in
some portions of primary ribosomal RNA transcripts. The splicing of introns in
mRNA precursors is:
A.
RNA-catalyzed in the absence of protein.
B.
Carried out by spliceosomes.
C.
Controlled by RNA polymerase.
D.
Regulated by RNA helicase.
Ans. B
Ref: Harpers Biochemistry 24th ed. p.426
MPL: 0.75
23. What is the function of a promoter site on DNA?
A.
Transcribes repressor
B.
Initiates transcription
C.
Codes for RNA polymerase
D.
Regulates termination
Ans. B
Ref: Harpers Biochemistry 24th ed. p. 420
MPL: 1.0
24. The sigma factor found in many bacteria is best described as a:
A.
Subunit of RNA polymerase responsible for the specificity of the initiation
of transcription.
B.
Subunit of DNA polymerase that allows for the synthesis in both 5 to 3
and 3 to 5 directions.
C.
Subunit of the 50S ribosome that catalyzes peptide bond synthesis.
D.
Subunit of the 30S ribosome to which mRNA binds.
Ans. A
Ref: Harpers Biochemistry 24th ed. p. 418
MPL: 0.75
25. A 23-year old man was rushed to the emergency room with nausea, vomiting,
and abdominal pain. Remnants of the death-cap wild mushroom Amanita
phalloides were noted upon laboratory examination of his vomitus. A liver biopsy
indicates massive hepatic necrosis. Care is supportive. A major toxin of the death
cap mushroom inhibits which of the following?
A.
DNA primase
B.
RNA nuclease
C.
DNA ligase
D.
RNA polymerase
Ans. D
Ref: Harpers Biochemistry 24th ed. p. 420
MPL: 0.75
26. The consensus sequence 5-TATAAAA-3 found ineukaryotic genes is almost
similar to a consensus sequence observed in prokaryotes. The consensus
sequence is important as the:
A.
Only site of binding of RNA polymerase II.
B.
Promoter site for all RNA polymerases.
C.
Termination site for RNA polymerase II.
D.
First site of binding of a transcription factor for RNA polymerase II.
Ans. D
Ref: Harpers Biochemistry 24th ed. pp. 421-422
MPL: 0.75
Ans. D
Ref: Harpers Biochemistry 24th ed. p.716
MPL: 1.0
33. Which of the following proteolytic enzymes is activated by acid hydrolysis of the
proenzyme form?
A.
Trypsin
B.
Elastase
C.
Pepsin
D.
Carboxypeptidase
Ans. C
Ref: Harpers Biochemistry 24th ed. p.636
MPL: 1.0
34. Which of the following amino acids is ionizable in proteins?
A.
Leucine
B.
Histidine
C.
Valine
D.
Alanine
Ans. B
Ref: Harpers Biochemistry 24th ed. p. 294
MPL: 0.75
35. The oxygen carrier of muscle is the globular protein myoglobin. Which of the
following amino acids is highly likely to be localized within the interior of the
molecule?
A.
Arginine
B.
Aspartic acid
C.
Glutamic acid
D.
Valine
Ans. D
Ref: Harpers Biochemistry 24th ed. p.53
MPL: 0.75
36. Which of the following statements concerning immunoglobulins is most accurate?
A.
IgE is the principal antibody in the serum.
B.
The heavy chains are similar in each class of immunoglobulin.
C.
The constant regions of the heavy chains are the same in each class of
immunoglobulin.
D.
IgE is the major immunoglobulin found in external secretions.
Ans. C
Ref: Harpers Biochemistry 24th ed. p.718
MPL: 1.0
37. Under normal conditions in the blood, which of the following amino acid residues
of albumin is neutral?
A.
Arginine
B.
Aspartate
C.
Glutamine
D.
Histidine
Ans. C
Ref: Harpers Biochemistry 24th ed. p. 294
MPL: 0.75
38. A child develops chronic diarrhea and liver inflammation in early infancy when the
mother begins using formula that includes corn syrup. Evaluation of the child
demonstrates sensitivity to fructose in the diet. Which of the following glycosides
contains fructose and therefore should be avoided when feeding or treating this
infant?
A.
Sucrose
B.
Oaubain
C.
Lactose
D.
Maltose
Ans. A
Ref: Harpers Biochemistry 24th ed. p.135
MPL: 0.75
39. Which of the following carbohydrates would be most abundant in a diet of strict
vegetarians?
A.
Amylose
B.
Lactose
C.
Cellulose
D.
Glycogen
Ans. C
Ref: Harpers Biochemistry 24th ed. p. 141
MPL: 1.0
40. The major metabolic product under normal circumstances by erythrocytes and by
muscle cells during intense exercise is recycled through the liver in the Cori
cycle. The metabolite is:
A.
Oxaloacetate
B.
Glycerol
C.
Alanine
D.
Lactate
Ans. D
Ref: Harpers Biochemistry 24th ed. p. 200-201
MPL: 0.75
41. Chronic alcoholics require more ethanol than do nondrinkers to become
intoxicated because of a higher level of a specific enzyme levels, the availability
of what other substance is rate-limiting in the clearance of alcohol?
A.
NADH
B.
NAD+
C.
FADH
D.
FAD+
Ans. B
Ref: Harpers Biochemistry 24th ed. pp. 601-603
MPL: 0.25
42. Following a fad diet of skimmed milk and yogurt, an adult female patient
experiences abdominal distention, nausea, cramping, and pain followed by
watery diarrhea. This set of symptoms is observed each time the said meal is
consumed. A most likely diagnosis is:
A.
Steatorrhea
B.
Lactase deficiency
C.
Sialidase deficiency
D.
Lipoprotein deficiency
Ans. B
Ref: Harpers Biochemistry 24th ed. p. 645
MPL: 0.1
43. A percentage of Filipino population may flush and feel discomfort after drinking
small amounts of ethanol in alcoholic beverages. This reaction is due to genetic
variation in an enzyme that metabolizes the liver metabolite of alcohol, which is:
A.
Methanol
B.
Acetone
C.
Acetaldehyde
D.
Glycerol
Ans. C
Ref: Harpers Biochemistry 24th ed. p. 264
MPL: 0.75
44. Which of the following enzymes catalyzes the high-energy phosphorylation of
substrates during glycolysis?
A.
Pyruvate kinase
B.
Phosphoglycerate kinase
C.
Triosephosphate isomerase
D.
Glyceraldehyde-3-phosphate dehydrogenase
Ans. D
Ref: Harpers Biochemistry 24th ed. p.176
MPL: 1.0
45. Which of the following enzymes is common to both glycolysis and
gluconeogenesis?
A.
Pyruvate carboxylase
B.
Hexokinase
C.
Phosphoglycerate kinase
D.
Fructose 1,6-bisphosphatase
Ans. C
Ref: Harpers Biochemistry 24th ed. p.194
MPL: 0.75
46. During the first week of a diet of 1500 calories per day, the oxidation of glucose
via glycolysis in the liver of a normal 59-kg woman is inhibited by the lowering of
which of the following?
A.
Citrate
B.
ATP
C.
Ketone bodies
D.
Fructose-2,6-bisphosphatase
Ans. D
Ref: Harpers Biochemistry 24th ed. p.176
MPL: 0.75
47. Familial fructokinase deficiency causes no symptoms because:
A.
Hexokinase can phosphorylate fructose.
B.
Most tissues utilize fructose.
C.
Liver fructose-1-phosphate aldolase is still active.
D.
Excess fructose spills into the bowel and is eliminated in the feces.
Ans. A
Ref: Harpers Biochemistry 24th ed. p. 214
MPL: 0.75
48. A newborn begins vomiting after feeding, becomes severely jaundiced, and has
liver disease. Treatment for possible sepsis is initiated, and the urine is found to
have reducing substances. A blood screen for galactosemia is positive, and
lactose-containing substances are removed from the diet. Lactose is toxic in this
case because:
A.
Excess glucose accumulated in the blood.
B.
C.
D.
Ans. B
Ref: Harpers Biochemistry 24th ed. p. 205
MPL: 0.25
49. Which of the following enzymes catalyzes phosphorylation with the use of
inorganic phosphate?
A.
Hexokinase
B.
Phosphofructokinase
C.
Phosphoglycerate kinase
D.
Glyceraldehyde-3-phosphate dehydrogenase
Ans. D
Ref: Harpers Biochemistry 24th ed. p. 179
MPL: 0.75
50. After a well-rounded breakfast, which of the following would be expected to
occur?
A.
Increased activity of pyruvate carboxylase
B.
Decreased activity of acetyl CoA carboxylase
C.
Decreased rate of glycogenesis
D.
Decreased rate of protein synthesis
Ans.
Ref.
MPL:
C
Harpers Biochemistry 24th ed. p. 179
0.75
10
53.
54. Which of the following mutations would produce a severe form of thalassemia?
A.
Deletion of one -globin locus
B.
Deletion of one -globin locus
C.
Oxidation of heme groups to produce methemoglobin
D.
Altered RNA processing at both
Ans.
Ref.
MPL
D
Harpers Biochemistry 24th ed. p. 734
0.75
55. The substitution of valine for glutamate at position 6 on the two chains in sickle
cell hemoglobin causes which of the following?
A.
Increased electrophoretic mobility at pH 7.0
B.
Increased solubility of deoxyhemoglobin
C.
Decreased polymerization of deoxyhemoglobin
D.
Unchanged primary structure
Ans.
Ref.
MPL
A
Harpers Biochemistry 24th ed. p. 476
0.75
56. An increased affinity of hemoglobin for oxygen may result from which of the
following?
A.
Initial binding of oxygen to one of the four sites available in each
deoxyhemoglobin molecule
B.
High pH
C.
High carbon dioxide levels
D.
High 2,3-bisphosphoglycerate levels within erthrocytes
Ans.
Ref.
MPL
A
Harpers Biochemistry 24th ed. p. 436
0.75
57. The functions of many enzymes, membrane transporters, and other proteins can
be quickly activated or deactivated by phosphorylation of specific amino acid
residues catalyzed by enzymes called:
A.
Cyclases
B.
Kinases
C.
Phosphatases
D.
Proteases
Ans
Ref.
MPL
B
Harpers Biochemistry 24th ed. p. 64-65
0.75
11
C
Harpers Biochemistry 24th ed. p. 86-88
0.75
B
Harpers Biochemistry 24th ed. p. 75-90
0.75
60. In the study of enzymes, the sigmoidal plot of substrate concentration versus
reaction velocity may indicate:
A.
Michaelis-Menten Kinetics
B.
Myoglobin binding oxygen
C.
Cooperative binding
D.
Competitive inhibition
Ans
Ref.
MPL
C
Harpers Biochemistry 24th ed. p. 75, 90
1.0
C
Harpers Biochemistry 24th ed. p. 86-88
0.75
A
Harpers Biochemistry 24th ed. p. 104-105
0.75
12
D
Harpers Biochemistry 24th ed. p. 104-105
0.75
64. A comatose laboratory technician is rushed into the emergency room. She dies
while you are examining her. Her most dramatic symptom is that her body is
literally hot to your touch, indicating an extremely high fever. You learn that her
lab has been working on metabolic inhibitors and that there is a high likelihood
that she accidentally ingested one. Which one of the following is the MOST likely
culprit?
A.
Barbiturates
B.
Piericidin A
C.
Dimercaprol
D.
Dinitrophenol
Ans
Ref.
MPL
D
Harpers Biochemistry 24th ed. p. 128
0.25
D
Harpers Biochemistry 24th ed. p. 117-118
0.75
66. As electrons are received and passed down the transport chain, the various
carriers are first reduced with acceptance of the electron and then oxidized with
loss of the electron. A patient poisoned by which of the following compounds has
the MOST highly reduced state of the respiratory chain carriers?
A.
Antimycin A
B.
Rotenone
C.
Carbon Monoxide
D.
Puromycin
Ans
Ref.
MPL
C
Harpers Biochemistry 24th ed. p. 128
0.25
67. Which of the following compounds is a member of the electron transport chain?
A.
Octanoyl carnitine
B.
Cytochrome c
C.
NADH
D.
Palmitoyl carnitine
Ans
Ref.
MPL
C
Harpers Biochemistry 24th ed. p. 128
0.75
13
68. All known effects of cyclic AMP in eukaryotic cells result from:
A.
Activation of the catalytic unit of adenylate cyclase
B.
Activation of synthetases
C.
Activation of protein kinase
D.
Stimulation of calcium release from the endoplasmic reticulum
Ans
Ref.
MPL
C
Harpers Biochemistry 24th ed. p. 165
0.75
B
Harpers Biochemistry 24th ed. p. 127
0.75
70. If all potential sources of ATP production are taken into account, the net number
of ATP molecules formed per molecule of glucose in aerobic glycolysis is:
A.
2
B.
6
C.
18
D.
36
Ans
Ref.
MPL
B
Harpers Biochemistry 24th ed. p. 176-184
0.75
D
Harpers Biochemistry 24th ed. p. 176-184
0.75
72. which of the following products of triacylglycerol breakdown and subsequent oxidation may undergo gluconeogenesis?
A.
Propionyl CoA
B.
Acetyl CoA
C.
All ketone bodies
D.
Some amino acids
Ans
Ref.
MPL
A
Harpers Biochemistry 24th ed. p. 284
0.75
14
Ans
Ref.
MPL
D
Harpers Biochemistry 24th ed. p. 267
0.75
D
Harpers Biochemistry 24th ed. p. 701
0.75
C
Harpers Biochemistry 24th ed. p. 301-380
0.75
76. A newborn becomes progressively lethargic after feeding and increases his
respiratory rate. He becomes virtually comatose, responding only to painful
stimuli, and exhibits mild respiratory alkalosis. Suspicion of urea cycle disorder is
aroused and evaluation of serum amino acids levels is initiated. In the presence
of hyperammonemia, production of which of the following amino acids is always
increased?
A.
Glycine
B.
Arginine
C.
Proline
D.
Glutamine
Ans
Ref.
MPL
D
Harpers Biochemistry 24th ed. p. 267
0.75
B
Harpers Biochemistry 24th ed. p. 534-536
0.75
D
Harpers Biochemistry 24th ed. p. 296-297
0.75
15
A
Harpers Biochemistry 24th ed. p. 322-325
0.75
80. The important receive group of glutathione in its role as antioxidant is:
A.
Serine
B.
Sulfhydryl
C.
Tyrosine
D.
Acetyl CoA
Ans
Ref.
MPL
B
Harpers Biochemistry 24th ed. p. 753
0.75
81. A newborn develops jaundice that requires laboratory evaluation. Which of the
following porphyrin derivatives is conjugated, reacts directly, and is a major
component of bile?
A.
Stercobilin
B.
Biliverdin
C.
Bilirubin
D.
Bilirubin diglucuronide
Ans
Ref.
MPL
D
Harpers Biochemistry 24th ed. p. 356
0.75
82. Which of the following poryphrins give stools their characteristic brown color?
A.
Biliverdin
B.
Urobilinogen
C.
Heme
D.
Stercobilin
Ans
Ref.
MPL
D
Harpers Biochemistry 24th ed. p. 354
0.75
83. Chylomicrons, IDL, LDL, and VLDL are all serum lipoproteins. What is the
correct ordering of these particles from the lowest to the highest density?
A.
LDL, IDL, VLDL, Chylomicrons
B.
Chylomicrons, VLDL, IDL, LDL
C.
VLDL, IDL, LDL, Chylomicrons
D.
Chylomicrons, IDL, VLDL, LDL
Ans
Ref.
MPL
B
Harpers Biochemistry 24th ed. p. 708
0.75
B
Harpers Biochemistry 24th ed. p. 250-252
0.75
16
85.
Which of the following steps in cholesterol biosynthesis is thought to be ratelimiting and the locus of metabolic regulation?
A.
Geranyl pyrophosphate to Farnesyl pyrophosphate
B.
Squalene to Lanosterol
C.
Lanosterol to Cholesterol
D.
3-hydroxy-3-metylglutaryl CoA to Mevalonic acid
Ans
Ref.
MPL
B
Harpers Biochemistry 24th ed. p. 274
0.75
86. Humans MOST easily tolerate a lack of which of the following nutrients?
A.
Protein
B.
Iodine
C.
Carbohydrate
D.
Lipid
Ans
Ref.
MPL
C
Harpers Biochemistry 24th ed. p. 285-286
0.75
D
Harpers Biochemistry 24th ed. p. 612-613
0.75
88. Which of the following vitaminswould MOST likely become deficient in a person
who develops a completely carnivorous lifestyle?
A.
Thiamine
B.
Niacin
C.
Cobalamin
D.
Vitamin C
Ans
Ref.
MPL
D
Harpers Biochemistry 24th ed. p. 612-613
0.75
89. Fully activated pyruvate carboxylase depends upon the presence of:
A.
Malate and Niacin
B.
Acetyl CoA and Biotin
C.
Acetyl CoA and Thiamine pyrophosphate
D.
Oxaloacetate
Ans
Ref.
MPL
B
Harpers Biochemistry 24th ed. p. 194
0.75
B
Harpers Biochemistry 24th ed. p. 606-607
0.75
17
91. Which of the following conditions would primarily produce a functional deficiency
of Vitamin K?
A.
Coumadin Therapy
B.
Broad Spectrum antibiotic
C.
Premature birth
D.
Lack of red meat in the diet
Ans
Ref.
MPL
A
Harpers Biochemistry 24th ed. p. 727
0.75
92. A 3 month old boy presents with poor feeding & growth, hypotonia, lactic
acidemia, and mild acidosis. The pyruvate to lactate ratio is high, and there is
decreased conversion of pyruvate to Acetyl CoA. Which of the following may be
considered for therapy?
A.
Thiamine
B.
FFA
C.
Biotin
D.
Vitamin C
Ans
Ref.
MPL
A
Harpers Biochemistry 24th ed. p. 183
0.25
93. A 2-year old child presents with cough and bronchitis, growth failure, & chronic
diarrhea with light-colored foul smelling stools. A deficiency of which vitamin
should be considered?
A.
Vit B6
B.
Vit C
C.
Vit A
D.
Vit B1
Ans
Ref.
MPL
C
Harpers Biochemistry 24th ed. p. 614-617
0.25
94. an infant presents with prominent forehead, bowing of the limbs, broad & tender
wrists, swelling at the costochondral junction of the ribs, and irritability. Which of
the following treatments is the most appropriate for this patient?
A.
Removal of eggs from diet
B.
Milk & Sunlight exposure
C.
Diet of baby food containing liver & ground beef
D.
Diet of baby food containing leafy vegetables
Ans
Ref.
MPL
C
Harpers Biochemistry 24th ed. p. 613
0.25
95. Allopurinol effectively treats gout but has NO effect on the severe neurological
symptoms of Lesch-Nyhan patients because it does not:
A.
Decrease de Novo purine synthesis
B.
Decrease de Novo Pyrimidine syntheis
C.
Inhibit xanthine oxidase
D.
Increase PRPP levels
Ans
Ref.
MPL
A
Harpers Biochemistry 24th ed. p. 378
0.75
18
C
Harpers Biochemistry 24th ed. p. 381
0.75
97. Which of the following contributes nitrogen atom to both purine & pyrimidine
rings?
A.
Aspartate
B.
Carbonage PO4
C.
CO2
98. What is the end product of fatty acid synthase activity in human?
A.
Palmitic acid
B.
Palmetoleic acid
C.
Linoleic
D.
Arachidonic acid
Ans
Ref.
MPL
A
Harpers Biochemistry 24th ed. p. 216-223
0.75
99. For every 2 moles of free glycerol released by lipolysis of triglycerides in adipose
tissue?
A.
1 mole of glucose can be synthesized via gluconeogenesis
B.
2 moles of triacrylglyceride is released
C.
2 moles of FFA is released
D.
3 moles of Acyl CoA is produced
Ans
Ref.
MPL
A
Harpers Biochemistry 24th ed. p. 267
0.75
100.
A 45 year old man ha s a mild heart attack and is placed on diet and
Mevastatin therapy. Which of the following will result in this therapy?
A.
Low blood glucose level
B.
Low blood LDLs
C.
High blood cholesterol
D.
Low oxidation of Fa
Ans
Ref.
MPL
B
Harpers Biochemistry 24th ed. p. 281
0.75
19
20