Download Examination 2: Chapters 8 through 11

Examination 2: Chapters 8
through 11
Question
Shortcut: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
23 24 Home Page
This exam combines questions from exams given during past years.
The correct answer, relative objective, and percent of the class
answering each question correctly is at the end of the examination.
Questions:
1. The enzyme of glycolysis that converts dihydroxyacetone phosphate to glyceraldehyde-3phosphate can be categorized into one of six types of enzymes. This enzyme is most
appropriately called a(n):
A.
B.
C.
D.
E.
Oxidoreductase
Transferase
Hydrolase
Lyase
Isomerase
Answer
Top
2. Diisopropylphosphofluroridate and sarin are mechanism based inhibitors. They form:
A.
B.
C.
D.
E.
Weak bonds with enzymes like xanthine oxidase
Hydrogen bonds with enzymes like acetylcholinesterase
Van Der Waals bonds with cyclooxygenase
Covalent bonds with enzymes like xanthine oxidase
Covalent bonds with enzymes like acetylcholinesterase
Answer
3.
Top
On the following plot, N represents the curve for an allosteric enzyme with no allosteric
activators or inhibitors added. If an allosteric activator was added, which curve would one
obtain?
A.
B.
C.
D.
Curve
Curve
Curve
Curve
A
B
C
D
Answer
Top
4. This small protein can have dramatic effects on the activities of enzymes in response to
changes in intracellular calcium ion concentration:
A.
B.
C.
D.
E.
Calcitonin
Calsequesterin
Calmodulin
Calcitriol
Calciferol
Answer
Top
5. Pennicillin inhibits a vital enzyme step in bacterial growth. It is highly specific for the enzyme
and binds the active site very tightly because:
A.
B.
C.
D.
E.
is a Machaelis-Menten substrate
it resembles the transition state
it is a pure carbohydrate
it is an positive allosteric modifier of the enzyme
it contains two fatty acids where the enzyme has two charged aspartate residues
Answer
Top
6. In the liver, most ingested ethanol is initially converted to which compound and by which
enzyme, respectively?
A.
B.
C.
D.
E.
acetone, alcohol dismutase
methanol, alcohol kinase
acetaldehyde, alcohol dehydrogenase
ketone bodies, NADH
thiamine, thiamin pyrophosphate
Answer
Top
7. Dennis "the menace" Veere ingested the insecticide malathion. His symptoms of salivating,
tearing, sweating, and defecating were caused specifically by the organophosphate toxin binding
to which of the following?
A.
B.
C.
Prostaglandins
Smooth muscle cell membranes
Neurotransmitters
D. Hexokinases
E. Acetylcholinesterases
Answer
Top
8. Allopurinol is a drug used to treat gout. It acts as a suicide inhibitor of which of the following?
A.
B.
C.
D.
E.
Hypoxanthine
Glycopeptidyl transpeptidase
Uric acid
Xanthine oxidase
Guanine
Answer
Top
9. Which of the following statements about allosteric enzymes is CORRECT?
A.
B.
C.
D.
E.
The binding of substrate to any active site affects the other active sites
The plot of initial velocity vs. substrate concentration is a straight line
The Keq of the reaction is increased when allosteric activator is bound
The enzymes contains only one polypeptide chain
Allosteric activators bind to all active sites equally
Answer
Top
10. The most likely effect of a non-competitive inhibitor on an Michaelis-Menten enzyme is to
A.
B.
C.
D.
E.
Increase the Vmax
Decrease the Vmax
Increase both the Vmax and the Km
Decrease both the Vmax and the Km
Shift the curve to the left
Answer
Top
11. Enzymes catalyze reactions by
A.
B.
Increasing the free energy of the system so that the change in free energy is positive
Increasing the free energy of the substrate so that it is greater than the free energy of
the product
C. Changing the equilibrium constant for the reaction
D. Decreasing the free energy of activation
E. Decreasing the free energy of the product so that it is less than the free energy of the
substrate
Answer
Top
12. The enzyme hexokinase is
A.
B.
C.
D.
E.
Usually found in liver
Uses fructose as a substrate
Requires sulfate as a substrate
Is found everywhere glucokinase is found
Is inhibited by glucose-6-phosphate
Answer
Top
13. cAMP
A.
B.
C.
D.
E.
is created by the enzyme phosphodiesterase
is destroyed by the enzyme protein kinase A
is destroyed by the enzyme adenylate cyclase
will bind to the regulatory subunit of protein kinase A
increases in concentration whenever insulin is present.
Answer
Top
14. Epinephrine binds to α1-receptors in the liver membrane. This binding
A.
B.
C.
D.
E.
increases the concentration of phosphatidyl inositol trisphosphate in the membrane
activates phospholipase C
decreases the concentration of diacylglycerol
increases calcium stored in the endoplasmic reticulum
inhibits protein kinase C
Answer
Top
15.Assume the patient is fasting and then begins to eat a high carbohydrate meal. Following an
increase in blood glucose, the message of glucagon is, in part, terminated by
A.
B.
C.
D.
E.
decreasing proteolysis in the liver
increasing glucagon release from alpha-cells of the pancreas
decreasing the GTPase activity of Gαs-stimulatory subunit
decreasing the cAMP phosphodiesterase activity
increasing protein phosphatase activity in the cell
Answer
Top
16. Concerning Mya Sthenia who has myasthenia gravis, she has
A.
B.
C.
D.
E.
hypreactive nerves releasing too much epinephrine
too many epinephrine receptors
too little active acetylcholineesterase
too little acetylcholine
too few acetylcholine receptors
Answer
Top
17. During the fasting state, the release of fatty acids from adipose tissue is increased. At least
part of the signal for this release is carried by
A.
B.
C.
D.
E.
insulin from beta-cells of the pancreas
epinephrine from alpha-cells of the pancreas
epinephrine from the adrenal medula
glucagon from the adrenal medula
cortisol from the alpha-cells of the pancreas
Answer
Top
18. Which of the following hormones binds to a receptor in the nucleus or cytosol of target cells?
A.
B.
C.
D.
E.
adrenalin
cortisol
epinephrine
insulin
glucagon
Answer
Top
19. In the Ras and MAP kinase pathway, the last step in the pathway is catalyzed by MAPkinase. MAP-kinase
A.
B.
C.
D.
E.
phosphorylates a transcription factor
binds to Grb-2
activates adenylate cyclase
activates phospholipase C
binds to a glucocorticoid response element
Answer
Top
20. In the insulin signal transduction pathway that leads to increases in the diacylglycerol and
inositoltrisphosphate second messengers, What is the first signal transduction protein that binds
to the IRS?
A.
B.
C.
D.
E.
Phosphatidylinositol-3-kinase
GRB2
Phospholipase C
MAP Kinase
Adenylate cyclase (adenylyl cyclase)
Answer
Top
21. The following enzyme reaction is catalyzed by Acetyl CoA Carboxylase during fatty acid
synthesis:
Acetyl CoA + CO2 + ATP = Malonyl CoA + AMP + Pi
This enzyme is most appropriately called a(n):
A.
B.
C.
D.
E.
Oxidoreductase
Transferase
Hydrolase
Lyase
Ligase
Answer
Top
22. How does the aspirin (acetylsalicylic acid) inhibit prostaglandin endoperoxide synthase
(cyclooxygenase)?
A.
B.
C.
D.
E.
It
It
It
It
It
acetylates the active site serine
acts as a feed back inhibitor
acts as a product inhibitor
causes glycosylation of the N-terminus
forms a disulfide bond with glycine at the active site
Answer
Top
23. Phosphorylase kinase activates muscle glycogen phosphorylase by
A.
B.
C.
D.
E.
Converting glycogen phosphorylase a to glycogen phosphorylase b
Phosphorylating a seryl residue on glycogen phosphorylase
Activating protein phosphatase
Binding to the AMP allosteric binding site
Acting as a negative allosteric effector
Answer
Top
24. Concerning Al Martini who is an alcoholic, assume that the Vmax of cytosolic alcohol
dehydrogenase enzyme and the MEOS system are equal in Al's liver and that the KM's are 0.04
mM and 11 mM, respectively. If Al consumes one ounce of alcohol so that his blood level is 6.4
mM,
A.
B.
C.
D.
E.
The MEOS will oxidize more alcohol than the alcohol dehydrogenase enzyme
The alcohol dehydrogenase enzyme will oxidize more alcohol than the MEOS system
The MEOS will reduce more alcohol than the alcohol dehydrogenase enzyme
The alcohol dehydrogenase enzyme will reduce more alcohol than the MEOS system
Since the Vmax's are the same the amount of alcohol converted by the two systems will
be equal
Examination 1: Chapters 4 through 7
Question
Shortcut: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 2
9 30 31,32, 33, 34, 35, 36, Home Page
This exam combines questions from exams given during past years. The correct
answer, relative objective, and percent of the class answering each question correctly
is at the end of the examination.
Questions:
1. The two most important buffer systems in blood are:
A.
B.
C.
D.
E.
Phosphorylated organic metabolites and hemoglobin
Inorganic phosphate and hemoglobin
Phosphorylated organic metabolites and pyruvate
Hemoglobin and bicarbonate
Hemoglobin and albumin
Answer
Top
2. The pH of blood changes from normal to 7.25. As a result, the patient will:
A.
B.
C.
D.
E.
Breathe
Breathe
Breathe
Breathe
Breathe
more
more
more
more
more
slowly and the carbonic acid concentration will rise
slowly and the serum bicarbonate concentration will rise
slowly and the pH will rise
quickly and the bicarbonate concentration will rise
quickly and the carbonic acid concentration will drop
Answer
Top
3. Di Beatty is a patient who has had IDDM for seven years. She missed her scheduled insulin
shot and ate a candy bar. She was brought to the clinic after developing ketoacidosis..
Compared to normal, you would expect:
A.
B.
C.
D.
E.
higher PaCO2 and higher serum bicarbonate
lower PaCO2 and higher serum bicarbonate
lower PaCO2 and lower serum bicarbonate
higher PaCO2 and lower serum bicarbonate
no change in PaCO2 and higher bicarbonate
Answer
Top
4. An acid anhydride is formed by removing water from
A.
B.
C.
D.
E.
A sulfhydryl group and a carboxylic acid
An alcohol and a carboxylic acid
An amino group and a carboxylic acid
An alcohol group and an inorganic phosphate
A carboxylic acid and an inorganic phosphate
Answer
Top
5. The R-groups of the amino acids valine, leucine, and isoleucine are all:
A.
B.
C.
D.
E.
Nonpolar and aromatic
Polar and hydrophobic
Hydrophilic and branched chain
Polar and charged
Nonpolar and branched chain
Answer
Top
6. The pKa's for this amino acid are 2, 9, and 10.5. At a pH of 7.4, this amino acid has a net
positive charge. The amino acid is:
A.
B.
C.
D.
E.
Cystine
Histidine
Lysine
Asparagine
Valine
Answer
Top
7. At pH of 7, a salt bond would most likely form between the R-groups of:
A.
B.
C.
D.
E.
Valine and alanine
Histidine and lysine
Aspartate and arginine
Arginine and lysine
Histidine and glutamate
Answer
Top
8. Treatment for cystinurea could include:
A.
B.
C.
D.
E.
Oxidation of cystine to form 2 cysteine molecules
Reduction of cystine to form carboxyl groups which would be more soluble
Reduction of methionine in the diet, since this is a precursor to the synthesis of cysteine
Feeding of reduced glutathione, since this will oxidize cystine
Forming a salt bond between the disulfide bond and the R-group of glycine
Answer
Top
9. In this type of structure, most of carbonyl groups of peptide bonds forms a hydrogen bond
with the amide nitrogen of another peptide bond four amino acids further down the polypeptide
chain.:
A.
B.
C.
D.
E.
Alpha-helix
Beta-sheet
Beta-turn
Quaternary
Primary
Answer
Top
10. Concerning prion disease, the amyloid protein in the brain is thought to result from
A.
B.
C.
D.
E.
The
The
The
The
The
repression of the PrPc gene
accelerated conversion of PrPsc to amino acids
raising of the activation energy for the conversion of PrPsc to PrPc
raising of the activation energy for the conversion of PrPc to PrPsc
lowering of the activation energy for the conversion of PrPc to PrPsc
Answer
Top
11. Which of the following terms describes hemoglobin but not myoglobin?
A.
B.
C.
D.
E.
The protein contains hydrogen bonds
The protein contains a hydrophobic pocket that contains heme
Imidazole groups stabilize the ferrous ion
Hydrophobic interactions are partially responsible for the conformation of the molecule
The protein contains alpha and beta chains
Answer
Top
12. Concerning Di Abietes, HbA1c
A.
B.
C.
D.
E.
Measures blood glucose levels since birth
Is high when the enzyme hemoglobin glycosylase is active
Is best used to measure compliance over the last three days
Is lower if the person lives in a cold climate
Measures compliance over the last 6 weeks to eight weeks
Answer
Top
13. The alpha helix found in myoglobin can best be described as
A.
B.
C.
D.
E.
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
Motif structure
Answer
Top
14. Will Sichel has sickel cell anemia. His beta-chains are changed by the substitution of :
A.
B.
C.
D.
E.
a
a
a
a
a
nonpolar valine for a charged glutamate
nonpolar glutamate for a charged valine
polar valine for a polar glutamate
nonpolar valine for a nonpolar glutamate
charged valine for a noncharged aspartate
Answer
Top
15. You have an aqueous solution on your lab bench. The concentration of hydroxide ions is 5 x
10-7. You can determine:
A.
B.
C.
D.
E.
That the proton concentration is 2 x 10-6
That the proton concentration is 2 x 10-8
That the proton concentration is 1 x 10-14
That this is definitely a buffered solution
Nothing, not enough data is presented here
Answer
Top
16. Phosphate buffer in blood has a pKa = 6.8. If the pH of blood was 7.1, and the
concentration of HPO4 was 0.8 mmol/L , What would be the concentration of H2PO4?
A.
B.
C.
D.
E.
8 mmol/L
4 mmol/L
0.8 mmol/L
0.4 mmol/L
0.2 mmol/L
Answer
Top
17. Which of the following statements about buffers are TRUE?
A.
B.
C.
D.
E.
Their effectiveness does not depend upon their concentration
Maintenance of blood pH relies solely on the bicarbonate buffering system
They usually consist of a strong acid and its conjugate base
Buffers work best when the pH of the solution is within 1 pH unit of its pKa
Although some problems may arise, the body could survive without buffers
Answer
Top
18. You are working with arterial blood. The patient is acidotic with a pH = 7.1. The pKa for
carbonic acid is 6.1. The partial pressure of CO2 is 37 mm Hg. The concentration of CO2 is 1.1
mM. What is the concentration of bicarbonate ion?
A.
B.
C.
D.
E.
44 mM
22 mM
11 mM
1.1mM
0.11 mM
Answer
Top
19. Which of the following statements regarding monosaccharides is FALSE?
A.
D-glucose and D-galactose differ in the orientation of one hydroxyl group; thus, they
are epimers
B. D-glucose and D-galactose are stereoisomers
C. Most monosaccharides in humans exist in the D-configuration
D. Monosaccharides in solution usually exist as ringed structures
E. Gluconate and glucuronate are both formed by the reduction of glucose
Answer
Top
20. An amide bond is formed from a
A.
B.
C.
D.
E.
sulfhydryl group and a carboxyl group
carboxyl group and an amino group
phosphate group and an alcohol group
phosphate groupe and a carboxyl group
carboxyl group and another carboxyl group
Answer
Top
21. At physiologic pH, which R-groups of the following pairs could successfully form a salt bond?
A.
B.
C.
D.
E.
Phe - Trp
Asn - Val
Glu - Arg
Met - Cys
Ala - Arg
Answer
Top
22. Which of the following amino acids has an isoelectric point of about 11
A.
B.
C.
D.
E.
Leucine
Tryptophan
Methionine
Aspartate
Arginine
Answer
Top
23. All of the following are treatments for cystinuria EXCEPT:
A.
B.
C.
D.
E.
Increase fluid intake
Increased protein in the diet
Reduce methionine intake in diet
Sonic fracturing of cystine stones
Drugs which convert cystine to more soluble compounds
Answer
Top
24. Which R-group of the following is MOST likely to form hydrogen bonds in aqueous solution?
A.
B.
C.
D.
E.
Proline
Alanine
Serine
Isoleucine
Valine
Answer
Top
25. One of the following is NOT usually a force that helps to hold the monomer units of a
quaternary protein together?
A.
B.
C.
D.
E.
Peptide bonds
Disulfide bonds
Hydrogen bonds
Salt bonds
Hydrophobic interactions
Answer
Top
26. Of the following states of hemoglobin (Hb), which is least likely to bind the next molecule of
oxygen (02)?
A.
B.
C.
D.
Hb
Hb (02)
Hb (02)2
Hb (02)3
Answer
Top
27. Assume that an acid and the salt of an acid are equally soluble at pH 7.7 and that the pKa
for the conversion of the salt to the acid is 5.7. As you add either the salt of the acid or the acid
to a solution buffered at 7.7, which would precipitate first?
A.
B.
The salt of the acid
The acid
Answer
Top
28. Which of the following statements regarding ligand binding is NOT correct?
A.
B.
C.
D.
E.
Some proteins require ligands in order to perform their function
Enzymes with their attached ligands are called holoenzymes
Ligands are synonymous with prosthetic groups
The heme group on hemoglobin is an example of a tightly bound ligand
Some apoproteins will bind to ligands
Answer
Top
29. Concerning a patient with diabetic ketoacidosis, which compound in her blood reacts with
nitroprusside?
A.
B.
C.
D.
E.
Glucose
Glucose oxidase
Beta-hydroxybutyrate
Acetoacetate
A long chain fatty acid
Answer
Top
30. Which of the following is a free radical?
A.
B.
C.
N2
O2OH-
D. alanine
E. NAD+
Answer
Top
31. Regarding any untreated person having diabetes, what level of fasting blood sugar would
you expect?
A.
B.
C.
D.
E.
55 mg/dL
70 mg/dl
90 mg/dl
110 mg/dL
126 mg/dL
Answer
Top
32. If a person breathes into a paper bag, you would expect their blood CO2 to
A.
B.
C.
D.
E.
decrease and their blood pH to increase
decrease and their blood pH to decrease
increase and their blood pH to increase
increase and their blood pH to decrease
remain the same because the kidney determines the blood CO2 concentration
Answer
Top
33. A thioester is formed by removing water from
A.
B.
C.
D.
E.
A sulfhydryl group and a carboxylic acid
An alcohol and a carboxylic acid
An amino group and a carboxylic acid
An alcohol group and an inorganic phosphate
A carboxylic acid and an inorganic phosphate
Answer
Top
34. Refer to the structures in Figure 1 below. Which column contains the structure for a
ketohexose?
A.
B.
C.
D.
E.
Column
Column
Column
Column
Column
A
B
C
D
E
Answer
Figure 1.
Top
35. Refer to the structures in Figure 1 above. Which column contains both sorbitol and a ketose?
A.
B.
C.
D.
E.
Column
Column
Column
Column
Column
A
B
C
D
E
Answer
Top
36. Refer to the structures in Figure 2 below. Which column contains the structure for adenine?
A.
B.
C.
D.
Column
Column
Column
Column
A
B
C
D
Answer
Examination 3: Chapters 19 through 21
Question
Shortcut: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 2
9 30 31,32, 33, Home Page
This exam combines questions from exams given during past years. The correct
answer, relative objective, and percent of the class answering each question correctly
is at the end of the examination.
Questions:
Top
1. Which of the following terms are used to describe the tendency of a reaction to
occur when the substrates and products of the reaction are at any concentration?
A.
B.
C.
D.
E.
ΔG
ΔGo
ΔGo'
-TΔS
ΔH
Answer
Top
2. For the enzyme reaction A+ B = C + D, Delta Go' = + 1 kcal/mol. This reaction will
proceed spontaneously in a forward direction if:
A.
B.
C.
D.
E.
The concentration of D is increased one-hundred fold
The concentration of C is increased one-hundred fold
The concentration of A is increased one-hundred fold
The concentration of B is lowered one-hundred fold
The concentration of both A and D are increased one-hundred fold
Answer
Top
3. During muscle contraction:
A.
B.
C.
D.
E.
ATP binds to the actin-ATPase
Low calcium concentration allows interaction of myosin and actin
ATP hydrolysis causes necessary changes in conformation
Binding of ATP to actin allows association of actin and myosin
AMP is the product of ATP hydrolysis
Answer
Top
4. Oxidative phosphorylation:
A. Is anaerobic
B. Requires AMP
C. Requires the electron transport system
D. Is not dependent upon development of a proton gradient
E. Is independent of mitochondria
Answer
Top
5. Patients with hyperthyroidism complain constantly of feeling hot and sweaty. All of
the following are reasons EXCEPT:
A. Thyroid hormone induces many proteins that catalyze the oxidation of fats,
carbohydrates, and proteins
B. Thyroid hormone stimulates the Na+,K+-ATPase
C. Thyroid hormone increases the flux through most anabolic pathways
D. All spontaneous reactions convert some free energy to heat
E. Thyroid hormone causes the non-enzymatic hydrolysis of ATP
Answer
Top
6. Which of the following is not a function of the citric acid cycle?
A.
B.
C.
D.
E.
Catabolism of carbon structures of some amino acids
Catabolism of acetate groups from acetyl CoA
The production of GTP
The production of NADPH
The production of carbon structures for the synthesis of some amino acids
Answer
Top
7. In the citric acid cycle, a substrate level phosphorylation is catalyzed by:
A.
B.
C.
D.
E.
Citrate synthase
Succinyl CoA synthetase
Fumarase
Isocitrate dehydrogenase
Citrate lyase
Answer
Top
8. In contrast to NADH, FAD(2H):
A.
B.
C.
D.
E.
Can donate electrons, but only two at a time, in a chemical reaction
Has a low affinity for its apoenzyme
Is very reactive in solution
Is an excellent feedback inhibitor
Is derived from a vitamin
Answer
Top
9. The anaplerotic reaction that links glycolysis to the TCA cycle:
A. Uses thiamin as a cofactor
B. Is called phosphoenolpyruvate carboxykinase
C. Produces oxaloacetate
D. Is activated by malonyl CoA
E. Is dependent upon vitamin B12
Answer
Top
10. Which of the following two enzymes are thought to be the major control enzymes
of the TCA cycle?
A.
B.
C.
D.
E.
Malate dehydrogenase and fumarase
Succinate dehydrogenase and fumarase
Succinyl CoA synthetase and succinate dehydrogenase
Succinyl CoA synthetase and alpha-ketoglutarate dehydrogenase
α-ketoglutarate dehydrogenase and isocitrate dehydrogenase
Answer
Top
11. Wet beriberi results in low peripheral resistance and cardiomyopathy. Both of
these symptoms are explained as follows:
A.
B.
C.
D.
E.
Thiamin pyrophosphate is a cofactor for pyruvate carboxylase
Without thiamin, the TCA cycle produces too much ATP
Thiamin is an important intermediate in the electron transport chain
Without thiamin, energy cannot be adequately produced by muscle cells
Thiamin permeabilizes membranes so no proton gradient can be established
Answer
Top
12. The ATP synthase responsible for most of the ATP synthesis in the body is
located:
A.
B.
C.
D.
E.
On the outer side of the outer mitochondria membrane
On the inner side of the outer mitochondria membrane
On the outer side of the inner mitochondria membrane
On the inner side of the inner mitochondria membrane
Free in the matrix of the mitochondria
Answer
Top
13. If electrons were removed from α-ketoglutarate and you could watch them move
down the electron transport system, the order of movement would be as follows:
A.
B.
C.
D.
E.
NADH, Complex I, CoQ, Complex III, Cytochrome C, Complex IV, H2O
NADH, Complex I, Complex II, CoQ, Cytochrome C, Complex IV, H2O
NADH, Complex II, CoQ, Cytochrome C, Complex III, Complex IV, H2O
NADH, Complex I, CoQ, Complex II, Cytochrome C, Complex III, H2O
NADH, Complex I, Complex II, Cytochrome C, Complex III, CoQ, Complex
IV, H2O
Answer
Top
14. Which of the following statements does NOT help explain the chemiosmotic
theory?
A. Protons move down a concentration gradient with negative free energy change
B. ADP and Pi combine to form ATP, this reaction has a positive change in free
energy
C. The inner mitochondria membrane is impermeable to protons
D. The only way protons can enter the mitochondria is through the ATP synthase
with the concomitant synthesis of ATP
E. The outside of the mitochondria is negative with respect to the matrix
Answer
Top
15. A mitochondrion is producing ATP at a constant rate and, then, a chemical
uncoupler is added. Compared to before the uncoupler was added:
A.
B.
C.
D.
E.
Less heat would be produced
Less water would be produced
More NADH would be oxidized
More ATP would be produced
The proton gradient across the membrane would be increased
Answer
Top
16. Regarding Cora Nari, which of the following statements about her heart attack and
subsequent treatment and effects are FALSE?
A. Tissue plasminogen activator causes an increased production of plasmin
B. Tissue plasminogen activator can be given following a heart attack to dissolve
blood clots
C. Because of its high energy demands, the normal heart relies on anaerobic
respiration to meet its needs
D. Nitroprusside can be given following a heart attack to dilate blood vessels
E. Cardiac muscle cells, sperm cells, and other active cells have a relatively high
number of mitochondria
Answer
Top
17. The cleavage of the high-energy bond of ATP into ADP and Pi is an example of
what type of reaction?
A.
B.
C.
D.
E.
Oxidation-reduction
Phosphorylation
Acetylation
Hydrolysis
Amination
Answer
Top
18. Delta-G is negative, Delta-Go' is positive. Will the reaction occur spontaneously?
A. Yes
B. No
C. Not enough information to determine the answer
Answer
Top
19. Which of the following is NOT an example in which ATP is utilized in the body
for work?
A.
B.
C.
D.
E.
Contraction of muscle
Entry of water into cells through specific pores
Phosphorylation of glucose by hexokinase
Maintenance of the Na+ and K+ concentration gradients
Formation of glycosidic bonds to make glycogen
Answer
Top
20. Which of the following is NOT a step during muscle contraction?
A.
B.
C.
D.
E.
The terminal end of a myosin filament binds ATP
Cleavage of ADP into AMP and Pi provides energy for mechanical work
Thick myosin filaments bind thin actin filaments
Presence of calcium enables myosin to bind actin
ATP is cleaved by an ATPase located on the myosin filament
Answer
21. The phosphorylation of glucose to glucose-6-phosphate has a Delta Go'of +3.3
kcal/mol. So why does the reaction occur in almost every cell of our body?
A.
B.
C.
D.
E.
Top
Glucose becomes unstable intracellularly
Hexokinase is present
ATP hydrolysis
High concentration of glucose in the blood compared to cell
This reaction is coupled to another that has a much higher positive Delta Go
Answer
Top
22. Which of the following statements regarding electron-accepting coenzymes is
INCORRECT?
A.
B.
C.
D.
FAD accepts electrons as the hydrogen atom
NADH is the reduced form of the coenzyme
FAD(H2) is synthesized from the vitamin riboflavin
The Delta Go' for the oxidation of NADH by the electron transport chain is
negative
E. The electrons donated to these coenzymes are subsequently removed by the
enzymes of the TCA cycle
Answer
Top
23. Which of the following statements regarding the TCA cycle is CORRECT?
A. The rate-limiting step involves the enzyme malate dehydrogenase
B. For each acetyl CoA entering the cycle, two molecules of CO2 are produced
C. For each acetyl CoA entering the cycle, 24 high-energy phosphate bonds are
produced
D. The cycle will not function unless glutamate is present
E. The TCA cycle occurs in the rough endoplasmic reticulum of virtually every
cell in the body
Answer
Top
24. Which of the following statements regarding the alpha-ketoglutarate
dehydrogenase complex is INCORRECT?
A.
B.
C.
D.
E.
One of its coenzymes - lipoic acid - comes from the vitamin B-carotene
It requires FAD as a coenzyme
Carbon dioxide is produced by this complex
One of its coenzymes - CoASH - comes from the vitamin pantothenate
It catalyzes the reaction converting a-ketoglutarate into succinyl CoA
Answer
Top
25. Which enzyme complex in the TCA cycle requires the cofactors thiamine
pyrophosphate, lipoic acid, CoA, FAD and NAD+?
A.
B.
C.
D.
E.
Citrate synthase
a-ketoglutarate dehydrogenase
Succiny-CoA synthetase (succinate thiokinase)
Malate dehydrogenase
Fumarase
Answer
26. Which of the following statements about the coenzyme FAD is INCORRECT?
A. It accepts single electrons
B. The TCA cycle enzyme that transfers electrons to FAD is found in the inner
mitochondrial membrane
C. It is very reactive in solution
D. It remains tightly bound to the holoenzyme
E. FADH2 is an important allosteric inhibitor of the TCA cycle
Answer
Top
27. Which of the following statements about the TCA cycle is CORRECT?
A. Citrate is frequently used for gluconeogenesis in the liver
B. The production of oxaloacetate by pyruvate carboxylase is one of several
anaplerotic reactions for the TCA cycle
C. Succinyl CoA is used to create a neurotransmitter in the brain
D. Pyruvate dehydrogenase helps convert pyruvate into malate
E. Pyruvate carboxylase is only found in RBCs
Answer
Top
28. Which of the following statements regarding the pyruvate dehydrogenase complex
is INCORRECT?
A. When the complex is phosphorylated, it is inactive
B. Binding of pyruvate to the enzyme complex decreases the activity of the
kinase
C. High [ADP] stimulates the conversion of pyruvate to acetyl CoA
D. The phosphatase which activates the complex is itself inhibited by Ca2+
E. The kinase associated with the pyruvate dehydrogenase complex is an enzyme
that adds phosphate groups
Answer
Top
29. Which of the following statements regarding Complex II is INCORRECT?
A. This is one means by which the TCA cycle is linked to the electron-transport
chain
B. Succinate dehydrogenase is embedded in the inner mitochondrial membrane
C. Neither the single- or 2-electron forms of FAD dissociate from the enzyme
D. Complex II transfers its electrons directly to cytochrome c
E. The transfer of electrons from FAD(2H) to the electron-transport chain results
in the synthesis of approximately 1.5 ATPs
Answer
Top
30. Which of the following are in the correct sequence?
A.
B.
C.
D.
E.
Cytochrome Q; NADH dehydrogenase; Cytochrome c; Cytochrome oxidase
Complex I; Cytochrome c; Complex II; Cytochrome oxidase
NADH dehydrogenase; Cytochrome b-c1; Cytochrome c; Cytochrome oxidase
Succinate dehydrogenase; Coenzyme Q; Cytochrome oxidase; Cytochrome c
Complex I; Complex II; Coenzyme Q; Cytochrome oxidase
Answer
Top
31. All of the following can act as "uncouplers" EXCEPT:
A.
B.
C.
D.
E.
Brown adipose tissue
Proton ionophores
Thermogenin (in infants)
Thyroid hormone
Cyanide
Answer
Top
32. A patient suffers a heart attack due to the blockage of an artery. The heart cells
downstream from the blockage will receive less oxygen which will in turn cause
A. [ATP] to increase
B. [ADP] to decrease
C. An increase in electron flow through the electron transport chain
D. [NADH] to increase
E. Anaerobic glycolysis to decrease
Answer
Top
33. A patient has hyperthyroidism. Compared to normal, you would expect that the
electron transport chain would
A.
B.
C.
D.
E.
increase electron flow (flux) through the chain
decrease the oxidation of NADH
decrease the production of water
decrease the pumping of protons across the membrane
increase its efficiency in terms of ATP production per NADH oxidized
Answer
Top
34.Assume standard biological conditions and that all the enzymes are present to
catalyze the reactions. Given the following data:
Glucose + Pi = glucose-6-P + H2O, ΔGo′ = +3.3 kcal/mol
ATP + H2O = Pi + ADP,
ΔGo′ = -7.0 kcal/mole
o
Calculate the ΔG ′ for the following reaction and determine whether the reaction is
spontaneous
Glucose + ATP --> Glucose-6-P + ADP
A.
B.
C.
D.
E.
–10.3 kcal/mol and spontaneous
+10.3 kcal/mol and not spontaneous
–3.7 kcal/mol and not spontaneous
+3.7 kcal/mol and not spontaneous
–3.7 kcal/mol and spontaneous
Examination 4: Chapters 22
through 28
Question
Shortcut: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
23 24 25 26 27 28 29, Home Page
This exam combines questions from exams given during past years.
The correct answer, relative objective, and percent of the class
answering each question correctly is at the end of the examination.
Questions:
1. The enzyme that controls the rate at which metabolites flow through glycolysis is:
A.
B.
C.
D.
E.
Hexokinase
Glucokinase
Phosphoglycerate kinase
Pyruvate kinase
Phosphofructokinase-1
Answer
Top
2. Which of the following is not a component of the Cori cycle:
A.
B.
C.
D.
E.
Aerobic glycolysis
Blood lactate
Gluconeogenesis
Blood glucose
Glycolysis in red blood cells
Answer
Top
3. Your patient comes to the emergency room with a bleeding ulcer. She has felt bad for several
days. She suffers from COPD smoking 2 packs per day. She appears cyanotic. You expect a:
A.
B.
C.
D.
E.
Low blood CO2
Low blood carbonic acid
High partial pressure of oxygen
High blood pH
High blood lactate
Answer
Top
4. If palmitoyl CoA undergoes beta-oxidation, the products will be:
A.
B.
C.
D.
E.
8
7
8
7
7
NADH
NADH
NADH
NADH
NADH
+
+
+
+
+
8
7
8
7
7
FADH2
FADH2
FADH2
FADH2
FADH2
+
+
+
+
+
9
8
8
7
6
Acetyl
Acetyl
Acetyl
Acetyl
Acetyl
CoA
CoA
CoA
CoA
CoA
Answer
Top
5. The following graph shows the increase of blood acetoacetate, beta-hydroxybutyrate, glucose
and free fatty acids during a fast. Which of the following is CORRECT?
A.
B.
C.
D.
E.
Curve
Curve
Curve
Curve
Curve
A
B
B
C
A
represents
represents
represents
represents
represents
glucose
free fatty acid
acetoacetate
glucose
beta-hydroxybutyrate
Answer
Top
6. Medium chain acyl CoA (MCAD) deficiency results in:
A.
B.
C.
D.
E.
Increased blood glucose following a meal
Increased ketone body synthesis during a fast
Decreased levels of liver ATP during a fast
Increased gluconeogenesis during a fast
Increase ketone body synthesis following a meal
Answer
Top
7. All other things being constant, an increase in stress hormones would result in an increase in:
A.
B.
C.
D.
E.
Fatty acid synthesis in adipose tissue
Blood amino acids for gluconeogenesis
Malonyl CoA concentrations in liver
Protein synthesis in muscle
Glycogen synthesis in muscle
Answer
Top
8. During the series of events following an increase in insulin, all of the following occur EXCEPT:
A.
B.
C.
D.
E.
Insulin binds its receptor, causing the autophosphorylation of receptor subunits
Active protein kinases can cause the induction/repression of genes
Glucagon-stimulated phosphorylation is reversed by the effects of insulin
Phosphorylation results in more glucose transporters in adipose tissue cells
Phosphorylation inhibits 3', 5'-phosphodiesterase
Answer
Top
9. Which of the following is NOT a result of insulin binding to its receptor on a muscle cell?
A.
B.
C.
D.
E.
The receptor undergoes a change in conformation
The receptor autophosphorylates tyrosyl residues
Phosphorylation of the insulin receptor substrate (IRS) is increased
More glucose transporters are inserted into the membrane
G-protein and adenylate cyclase are activated
Answer
Top
10. In a patient with NIDDM who has started taking a sulfonylurea drug, which of the following
is part of the mechanism?
A.
B.
C.
D.
E.
The
The
The
The
The
sulfonylurea
sulfonylurea
sulfonylurea
sulfonylurea
sulfonylurea
drug
drug
drug
drug
drug
binds to a calcium channel
causes the cell to become more polarized
increases the concentration of intracellular calcium
inhibits glycolysis in beta-cells
inhibits membrane depolarization
Answer
Top
11. Which of the following statements about glycogenolysis and glucose metabolism is TRUE?
A.
B.
C.
D.
E.
Glucose-6-phosphate from liver glycogen usually enters glycolysis
Glucose-6-phosphate from muscle glycogen sometimes enters the blood
Muscle cytosol contains glucose-6-phosphatase
Liver glycogenolysis and glycolysis are not usually active at the same time
Muscle glycolysis is inhibited by epinephrine
Answer
Top
12. Which of the following events helps in the incorporation of blood glucose into muscle
glycogen?
A.
B.
C.
D.
E.
Glucokinase produces glucose-6-phosphate
UDP-glucose pyrophosphorylase produces glucose-1-phosphate
Branching enzyme produces alpha-1,4-glucosidic bonds
ATP is a substrate for glycogen synthase
Hydrolysis of pyrophosphate makes the overall reaction exergonic
Answer
Top
13. All of the following activate muscle phosphorylase EXCEPT:
A.
B.
C.
D.
E.
AMP
Ca++- calmodulin
fight or flight
cyclic-AMP
protein phosphatase
Answer
Top
14. An absence of liver glucose-6-phosphatase is known as:
A.
B.
C.
D.
E.
Von Gierke's disease
McArdle's disease
Paget's disease
Wernicke-Korsakoff syndrome
Tay-Sachs disease
Answer
Top
15. Which of the following glycolytic intermediates and enzymes are in the CORRECT sequence?
A.
Glucose-6-phosphate; Phosphofructokinase-1; Phosphoenolpyruvate; Glyceraldehyde-3phosphate
B. Hexokinase; DHAP(dihydroxyacetonephosphate); Fructose-6-phosphate;
Glyceraldehyde-3-phosphate
C. Glucose-6-phosphate; Glyceraldehyde-3-phosphate; Pyruvate kinase;
Phosphoenolpyruvate
D. Glucose-6-phosphate; Phosphofructokinase-1; Phosphoenolpyruvate; Fructose-2,6bisphosphate
E.
Hexokinase; Phosphofructokinase-1; DHAP(dihydroxyacetonephosphate);
Phosphoenolpyruvate
Answer
Top
16. Which of the following glycolytic enzymes produce ATP during glycolysis
A.
B.
C.
D.
E.
Hexokinase
Glucokinase
Phosphofructokinase-1
3-phosphoglycerate kinase
glyceraldehyde-3-phosphate dehydrogenase
Answer
Top
17. The LDH reaction is reversible. Which of the following is not a substrate for this reaction?
A.
B.
C.
D.
E.
Lactate
Pyruvate
NAD+
NADH + H+
phosphoenolpyruvate
Answer
Top
18. In a cell with mitochondria, NADH is produced during glycolysis. Since NADH cannot cross
the mitochondrial membrane, the electrons of NADH are transferred to another compound which
can cross the mitochondrial membrane. The compound is
A.
B.
C.
D.
E.
Aspartate
Glutamate
Malate
Glutamine
Asparagine
Answer
Top
19. The activation of fatty acids involves all of the following players EXCEPT:
A.
B.
C.
D.
E.
ATP
Fatty acyl CoA synthetase
Enzyme bound fatty acyl AMP
Pyrophosphate
Fatty acylcarnitine
Answer
Top
20. Regarding the CPT I and the CPT II reactions, which of the following is NOT TRUE?
A.
This reaction is necessary before activated fatty acids can pass into the matrix from the
cytosol
B. CPT I is embedded in the outer mitochondrial membrane
C. CPT I is inhibited by malate
D. CPT II transfers the acyl group from acylcarnitine
E. CPT I causes the transfer of fatty acid from acyl-CoA to carnitine
Answer
Top
21. Which of the following is NOT TRUE of beta-oxidation?
A.
B.
C.
D.
Even chain fatty acids can be completely converted to acetyl CoA
The process has four steps, two of which use NAD+ to oxidize the fatty acyl group
For each NADH that is formed, 2.5 ATP can be generated
The overall beta-oxidation of a 16 carbon fatty acyl CoA to 8 acetyl CoAs yields 28 ATP
E.
The beta-oxidation of an odd chain fatty acid would yield a propionyl CoA
Answer
Top
22. Regarding the synthesis of ketone bodies, which of the following is TRUE?
A.
B.
C.
D.
E.
Ketone bodies are synthesized for stored energy during the fed state
HMG CoA is an intermediate that is converted into acetoacetate
Acetoacetate is converted to beta-hydroxybutyrate spontaneously, yielding a CO2
Ketone bodies are produced in the brain in response to starvation
In the liver, most acetoacetate produced can be converted to acetoacetyl-CoA
Answer
Top
23. Increased blood insulin specifically plays a major role in all of the following EXCEPT:
A.
B.
C.
D.
E.
Glucose storage as glycogen in liver and muscle
Conversion of glucose to triacylglycerols in liver
Amino acid uptake and protein synthesis in skeletal muscle
Promotion of the sparing of glucose utilized for energy in the brain during a fast
Stimulation of transport of glucose into muscle and adipose tissue
Answer
Top
24. In the synthesis of Insulin, which of the following is NOT TRUE?
A.
The α-cells of the pancreas are centered such that blood flow carries new glucagon over
the Β-cells explaining the inhibitory effect of glucagon on insulin release
B. Glucose is a major regulator of insulin release
C. Cleavage of proinsulin to insulin yields a C-Peptide
D. The chains of insulin are held together and in active conformation by disulfide bridges
E. The A chain of insulin is shorter than the B chain
Answer
Top
25. All the following are important in the glucagon second messenger cascade EXCEPT
A.
Glucagon binds causing the dissociation of GDP from and the association of GTP with
the G-protein
B. Adenylate cyclase catalyzes the conversion of ATP to cAMP
C. Phosphodiesterase catalyzes the conversion of cAMP to AMP
D. The receptor for glucagon undergoes an autophosphorylation which activates adenylate
cyclase
E. The cAMP binds to Protein Kinase A regulatory subunits, releasing catalytic subunits
Answer
Top
26. In liver and muscle, glycogen degradation is characterized by all of the following EXCEPT:
A.
B.
C.
D.
E.
The
The
The
The
The
activation of glycogen phosphorylase by insulin
yielding of glucose-1-phosphate residues by the enzyme glycogen phosphorylase
activity of a 4: 4- transferase to ensure the debranching
activity of an alpha-1,6- glucosidase that yields free glucose residues
use of inorganic phosphate by glycogen phosphorylase
Answer
Top
27. Which of the following is NOT true?
A.
B.
C.
D.
E.
Glucagon causes the breakdown of glycogen in liver to yield glucose to the blood
Insulin inhibits glycogenolysis in the liver
Epinephrine causes the glycogen in liver to be degraded to yield glucose to the blood
Insulin increases the transport of glucose into muscle cells
Epinephrine inhibits glycolysis of glucose in muscle cells
Answer
Top
28. A bodybuilding enthusiast injected insulin and tried to work out for several hours. He
continuously ingested the sports drink containing salts but no glucose, fatty acids, or protein. He
passed out and went into a coma. All of the following contributed to his coma EXCEPT
A.
B.
C.
D.
E.
The
The
The
The
The
insulin inhibited glycogenolysis
insulin inhibited gluconeogenesis
insulin inhibited hormones sensitive lipase
exercise used a lot of glucose
insulin inhibited glucose transporters
Answer
Top
29. Concerning Otto shape, during his long distance run the change in the concentration of AMP
ensures the increased uptake of fatty acyl CoA into his muscle mitochondria. This happens
because the AMP-dependent protein kinase catalyzes the phosphorylation of
A.
B.
C.
D.
E.
ADP
AMP
Carnitine palmitoyltransferase
Acetyl CoA carboxylase
Malic enzyme
Answer
Examination 5: Chapters 29 through 33
Question
Shortcut: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 2
9 30,Home Page
This exam combines questions from exams given during past years. The correct
answer, relative objective, and percent of the class answering each question correctly
is at the end of the examination.
Questions:
1. The enzyme phosphofructokinase-2/fructose-2,6-bisphosphatase plays a key role in
the control of glycolysis exerted by the insulin to glucagon ratio. If the insulin to
glucagon ratio increases, phosphofructokinase-2/fructose-2,6-bisphosphatase in the
liver would:
A. Become more phosphorylated and phosphofructokinase-2 would become more
active
B. Become less phosphorylated and phosphofructokinase-2 would become less
active
C. Become more phosphorylated and phosphofructokinase-1 would become more
active
D. Become less phosphorylated and phosphofructokinase-2 would become more
active
E. Become less phosphorylated and fructose-2,6-bisphosphatase would become
more active
Answer
Top
2. During a fast, the liver enzyme pyruvate kinase becomes:
A.
B.
C.
D.
More active and more phosphorylated
More active and less phosphorylated
Less active and more phosphorylated
Less active and less phosphorylated
Answer
Top
3. This patient has been taking dexamethasone for severe asthma for several weeks.
She has developed hyperglycemia and muscle weakness. A partial explanation of
these symptoms might be:
A.
B.
C.
D.
E.
The inhibition of net muscle protein catabolism
A decreased concentration of blood amino acids
Induction of phosphoenolpyruvate carboxykinase
An inhibition of fructose-1,6-bisphosphatase
Increased secretion of insulin
Answer
Top
4. The pentose phosphate pathway can, without help from glycolysis or
gluconeogenesis, perform the following EXCEPT:
A. The synthesis of NADPH from glucose-6-phosphate
B. The synthesis of ribose-5-phosphate from glucose-6-phosphate
C. The synthesis of ribose-5-phosphate from fructose-6-phosphate and
glyceraldehyde-3-phosphate
D. The synthesis of glucose-6-phosphate from ribose-5-phosphate
E. The synthesis of fructose-6-phosphate and glyceraldehyde-3-phosphate from
ribose-5-phosphate
Answer
Top
5. Which of the following would NOT require NADPH?
A.
B.
C.
D.
E.
The reduction of antioxidant vitamins
Detoxification reactions that use P450
The reductive biosynthesis of cholesterol
The biosynthesis of palmitate
The beta-oxidation of fatty acids
Answer
Top
6. A patient takes sulfa drugs for the first time and develops hemolytic anemia. The
other blood cells appear normal. The best explanation is:
A.
B.
C.
D.
E.
The red blood cells have more active glucose-6-phosphate dehydrogenase
The red blood cells have more glutathione reductase activity
The red blood cells have more NADH in their cytosol
The other cells have less active glucose-6-phosphate dehydrogenase activity
The other cells have higher NADPH concentrations
Answer
Top
7. After ingestion of a high carbohydrate meal, all of the following are true EXCEPT:
A.
B.
C.
D.
E.
Glucose transport into muscle and adipose tissue is increased
Glucose uptake and utilization by adipose tissue is increased
Glucose storage in glycogen is increased
Glycolysis in the liver is increased
Glucose uptake by the brain is increased
Answer
Top
8. When glucagon binds to a liver cell,
A.
B.
C.
D.
E.
G-protein binds to ATP
Adenylate cyclase is activated
Protein phosphatase is activated
Cyclic-AMP is decreased
The configuration of every protein mentioned above is changed
Answer
Top
9. After a 24 hour fast, the maintenance of blood glucose is largely a result of the
change in the insulin to glucagon ratio. All of the following help to explain this
mechanism EXCEPT:
A.
B.
C.
D.
E.
More free fatty acid is mobilized from adipose tissue
More glycerol is mobilized from adipose tissue
More acetyl CoA is produced from free fatty acid in the liver
Acetyl CoA activates pyruvate carboxylase
Oxaloacetate is used as the principal source of energy to drive
gluconeogenesis
Answer
Top
10. Bob was brought to the emergency room. His wife said that he was a 33 year old
and had IDDM (Type I). He had told her last night that he had forgotten whether he
had taken his injection. Since he couldn't remember, he gave himself another
injection. His blood glucose was 25 mg/dL. At the present time and compared to a
normal person, Bob has:
A.
B.
C.
D.
E.
High blood fatty acids
Low blood ketone bodies
High gluconeogenesis
High concentration of active protein kinase A in adipose cells
High cyclic-AMP levels in adipose cells
Answer
Top
11. Which of the following enzymes is NOT part of the pathway for converting
carbon atoms in glucose to carbon atoms in free fatty acids in the liver?
A. Pyruvate dehydrogenase
B.
C.
D.
E.
Pyruvate carboxylase
Citrate synthase
Citrate lyase
Alpha-ketoglutarate dehydrogenase
Answer
Top
12. All of the following are intermediates in the synthesis of triacylglycerol from
glucose following a high carbohydrate meal EXCEPT:
A.
B.
C.
D.
E.
Dihydroxyacetone phosphate
Glycerol-3-phosphate
Monoacylglycerol
Phosphatidic acid
Diacylglycerol
Answer
Top
13. Ginny has been fasting (500 kcal/day) for several days. All of the following would
be increased EXCEPT:
A.
B.
C.
D.
E.
Cyclic-AMP in adipose tissue
The activity of hormone sensitive lipase in adipose tissue
The concentration of glycerol phosphate in adipose tissue
The amount of free fatty acid bound to albumin in the blood
The amount of free fatty acid entering the liver mitochondria
Answer
Top
14. Phosphatidylethanolamine is converted to phosphatidylcholine in an enzyme
reaction that transfers three activated methyl groups to the ethanolamine converting it
to phosphatidylcholine. This reaction requires the cofactor:
A.
B.
C.
D.
E.
Biotin
Thiamine pyrophosphate
S-adenosylmethionine
Vitamin B12
Methylene tetrahydrofolate
Answer
Top
15. Which of the following is NOT a glycerophospholipid commonly found in cell
membranes:
A.
B.
C.
D.
E.
Phosphatidylglycine
Phosphatidylcholine
Phosphatidylserine
Phosphatidylethanolamine
Phosphatidylinositolbisphosphate
Answer
Top
16. You are a fourth year medical student on rounds in the pediatric unit. The patient
is a premature infant with respiratory distress syndrome. The attending physician asks
the students present to explain one molecular cause of the disease. Student 1 says that
the infant is not making enough dipalmitoylphosphatidylcholine. Student 2 says that
the infant is not able to make enough lecithin. Student 3 says that the infant is not able
to make enough sphingomyelin. Your best answer is:
A.
B.
C.
D.
E.
Students 1, 2, and 3 are all correct
Students 1 and 2 are both correct and student 3 is incorrect
Student 2 is correct and students 1 and 3 are both incorrect
Students 1,2,and 3 are all incorrect
Student 3 is correct and students 1 and 2 are both incorrect
Answer
Top
17. During gluconeogenesis, an increased concentration of acetyl-CoA in the liver cell
will activate:
A.
B.
C.
D.
E.
Mitochondrial pyruvate carboxylase
Mitochondrial phosphoenolpyruvate carboxykinase
Cytosolic phosphoenolpyruvate carboxykinase
Cytosolic pyruvate carboxylase
Cytosolic pyruvate kinase
Answer
Top
18. When pyruvate carboxylase and phosphoenolpyruvate carboxykinase are active,
futile cycling is prevented by:
A.
B.
C.
D.
Phosphorylation and activation of pyruvate kinase by insulin via cAMP
Dephosphorylation and inactivation of protein kinase by glucagon via cAMP
Phosphorylation and activation of protein kinase by insulin via cAMP
Phosphorylation and inactivation of pyruvate kinase by glucagon via cAMP
Answer
Top
19. Gluconeogenesis ends with the conversion of fructose-1,6-bisphosphate to glucose
in a series of three enzymatic steps. Which of the following statements regarding
these enzymes is TRUE:
A. All three of these enzymes release inorganic phosphate and two are also used
in the reverse reaction in glycolysis
B. Two of these enzymes release inorganic phosphate and the other is also used
in the reverse reaction in glycolysis
C. Two of these enzymes release inorganic phosphate, and two are also used in
the reverse reaction in glycolysis
D. One of these enzymes releases inorganic phosphate, and the other two are also
used in the reverse reactions in glycolysis
E. One of these enzymes releases inorganic phosphate, and all three enzymes are
used in the reverse reactions in glycolysis
Answer
Top
20. An increase in the insulin/glucagon ratio would lead to______________ and a(n)
__________conversion of phosphoenolpyruvate to pyruvate.
A.
B.
C.
D.
The dephosphorylation of pyruvate kinase and an increase in the
The phosphorylation of pyruvate kinase and an increase in the
The phosphorylation of pyruvate kinase and a decrease in the
The dephosphorylation of pyruvate kinase and a decrease in the
Answer
Top
21. The hexose monophosphate shunt is:
A. Found mostly in the mitochondria of muscle cells
B. Found mostly in the cytosol of cells that rely heavily upon anaerobic
glycolysis
C. Found mostly in the cytosol of cells that do not rely upon vitamin C or vitamin
D for protection against free radicals
D. Found in the mitochondria of all cells
E. Found in the cytosol of all cells
Answer
Top
22. If a cell needed to make exactly twice the amount of NADPH as ribose-5phosphate, which glycolytic substrate(s) would be most efficient:
A.
B.
C.
D.
E.
Glucose-6-phosphate and fructose-1,6-bisphosphate
Fructose-6-phosphate and dihydroxyacetone phosphate
Glucose-6-phosphate
Fructose-6-phosphate and glyceraldehyde-3-phosphate
Glucose-6-phosphate and dihydroxyacetone phosphate
Answer
Top
23. Glutathione is continuously being reduced and oxidized. Which group on the
molecule is actually being reduced and oxidized:
A.
B.
C.
D.
E.
The hydroxyl group of threonine
The sulfhydryl group of cysteine
The carboxyl group of aspartate
The reactive hydrogen of histidine
The amide group of asparagine
Answer
Top
24. A pathway exists that uses substrate(s) from the glycolytic pathway to produce
reducing agents that remove H2O2 from the cell. Al of the following enzymes are used
by that pathway EXCEPT:
A. 6-phosphogluconate dehydrogenase
B. Glucose-6-phosphate dehydrogenase
C. Cytochrome P450 monooxygenase
D. Glutathione reductase
E. Glutathione peroxidase
Answer
Top
25. A person fasts for 12 hours and then eats a high protein meal. About 45 minutes
later their blood is analyzed. Compared to blood levels before ingestion:
A. Insulin will be higher. Glucagon will be higher. Liver glycolysis will be active.
B. Insulin will be higher. Glucagon will be higher. Liver gluconeogenesis will be
active.
C. Insulin will be lower. Glucagon will be higher. Liver glycolysis will be active.
D. Insulin will be lower. Glucagon will be higher. Liver gluconeogenesis will be
active.
E. Insulin will be higher. Glucagon will be lower. Liver gluconeogenesis will be
active.
Answer
Top
26. Regarding dietary glucose entering the liver following a high caloric, high
carbohydrate meal. Which of the following statements is NOT true:
A.
B.
C.
D.
E.
Some glucose is converted to glycerol phosphate
Some glucose is stored as glycogen
Some glucose is used via aerobic glycolysis
Some glucose is used via anaerobic glycolysis
Some glucose is used for fatty acid synthesis
Answer
Top
27. When going from the fed state to the fasted state, the activity of the glycolytic and
gluconeogenic pathways are changed. Part of the mechanism for this change is:
A.
B.
C.
D.
E.
An increase in the activity of 3',5'-phosphosdiesterase
An increase in the activity of phosphofructokinase-2
An increase in the activity of fructose-2,6-bisphosphatase
A decrease in the activity of protein kinase
A decrease in the ativity of adenylate cyclase
Answer
Top
28. You meet your patient in the emergency room. She forgot that she took her first
shot of insulin last night and so she took a second shot. She is now in a hypoglycemic
coma. Which of the following is contributing to the low blood sugar:
A.
B.
C.
D.
E.
Insulin has activated the cyclic AMP cascade in the liver
Insulin has activated the cyclic AMP cascade in adipose tissue
Insulin has caused an increase in ketone bodies synthesis in the liver
Insulin has inhibited fructose-1,6-biphosphatase in the liver
Insulin has inhibited glucose uptake and released across the liver cell
membrane
Answer
Top
29. Both acetyl CoA and the acyl carrier protein
A.
B.
C.
D.
E.
Transfer one carbon units
React only with each other
Only react when vitamin B12 is present
Are synthesized from vitamin thiamine
Contain phosphopantetheine reactive groups
Answer
Top
30. Which of the following is NOT an intermediate in the synthesis of triaclglycerol
from glucose-6-phosphate and fatty acids in adipose tisssue:
A.
B.
C.
D.
E.
Glycerol
Dihydroxyacetone phosphate (DHAP)
Phosphatidic acid
Diacylglycerol
Acyl-CoA
Examination 6: Chapters 36 through 39
Question Shortcut: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 , Home
Page
This exam combines questions from exams given during past years. The correct
answer, relative objective, and percent of the class answering each question correctly
is at the end of the examination.
Questions:
1. During fasting, all of the following would tend to increase the flux through gluconeogenesis
EXCEPT:
A.
B.
C.
D.
E.
The
The
The
The
The
concentration of free amino acids increases
concentration of glycerol increases
concentration of cyclic-AMP rises
concentration of fructose-2,6-bisphosphate rises
enzyme phosphoenolpyruvate carboxykinase is induced
Answer
Top
2. All of the following contribute to the increase in ketone body synthesis in the liver during
fasting EXCEPT:
A.
B.
C.
D.
E.
The increased insulin to glucagon ratio activates lipoprotein lipase in adipose tissue
Increased blood concentrations of free fatty acids bound to albumin
Inactive acetyl CoA carboxylase
More flux through beta-oxidation
The liver makes more acetyl CoA than the TCA cycle can use
Answer
Top
3. A patient with type I diabetes has come to the emergency room with ketoacidosis. All of the
following might help to explain why her ketones are high EXCEPT:
A.
Protein kinase A in her liver is to high
B.
C.
D.
E.
Free fatty acids in her blood are too high
Too much acetyl-CoA is produced by the liver
Too much hydroxymethylglutaryl CoA is produced
Carnitine deficiency
Answer
Top
4. The pKa for ammonium ion is about 9.4 and the pH of blood is about 7.4. The ratio of
ammonia to ammonium ion (ammonia/ammonium ion) in blood is about:
A.
B.
C.
D.
E.
1/100
1/10
0
10/1
100/1
Answer
Top
5. Which of the following enzyme reactions takes place during the synthesis of urea from
ammonium ion and glutamate?
A.
B.
C.
D.
E.
Carbamoyl phosphate + citrulline = ornithine
Aspartate + citrulline + ATP = argininosuccinate + AMP + PPi
Argininosuccinate = aspartate + arginine
CO2 + NH4+ + 2 ADP = carbamoyl phosphate + 2 ATP
Argininosuccinate = arginine + urea
Answer
Top
6. All of the following would be expected to increase the activity of the urea cycle EXCEPT:
A.
B.
C.
D.
E.
Antibiotics
Switching to a high protein diet
Going from the fed state of a normal diet to a fasting state
An increase in gluconeogenesis
Stress
Answer
Top
7. Which of the following is an essential amino acid?
A.
B.
C.
D.
E.
Alanine
Glycine
Valine
Aspartate
Serine
Answer
Top
8. The products of the catabolism of cysteine are:
A.
B.
C.
D.
E.
Serine and phosphate
Serine and HCl
Pyruvate and sulfate
Serine and sulfate
Alanine and sulfate
Answer
Top
9. All of the following are substrates or products of the phenylalanine hydroxylase reaction
EXCEPT:
A.
B.
Tetrahydrofolate
H20
C. Dihydrobiopterin
D. Tyrosine
E. O2
Answer
Top
10. You suspect that your 12 year old male patient has an inborn error in methionine
metabolism. It may be that cystathionine synthase is deficient. If this is true, he should have
high serum concentrations of:
A.
B.
C.
D.
E.
Methionine
Cysteine
Cystathionine
α-ketobutyrate
Methyl cobalamin
Answer
Top
11. As a result of having the disease phenylketonuria, phenyl ketones are found in the urine.
The best explanation for this is:
A.
B.
C.
D.
E.
Tyrosine hydroxylase is absent and lactate dehydrogenase is absent
Phenylalanine hydroxylase is absent and aminotransferases are absent
Tyrosine hydroxylase is present and lactate dehydrogenase is present
Phenylalanine hydroxylase is present and tyrosine hydroxylase is absent
Phenylalanine hydroxylase is absent and aminotransferases are present
Answer
Top
12. Following a meal, glucose will be stored in liver glycogen because:
A.
B.
C.
D.
E.
Hexokinase will be phosphorylated as a result of the high insulin to glucagon ratio
Hexokinase will be dephosphorylated following a reduction in protein kinase A
Glycogen phosphorylase A will be inactivated by phosphorylation by protein kinase A
Phosphorylase kinase will be inactivated by phosphorylation by protein kinase A
Glycogen synthase will be activated by protein phosphatase
Answer
Top
13. The enzyme acetyl CoA carboxylase is activated following an increase in:
A.
B.
C.
D.
E.
Malonyl CoA
Protein kinase A activity
Cyclic AMP
Palmitoyl CoA
Proteins phosphatase activity
Answer
Top
14. The delivery of free fatty acids from lipoproteins into adipose tissue cells will be increased
by:
A.
B.
C.
D.
E.
Epinephrine
Norepinephrine
Diabetes
Glucagon
Insulin
Answer
Top
15. Compared to a normal person, a patient with diabetes Type II:
A.
B.
Will release more insulin from her beta cells following the same meal
Will produce less glucose via gluconeogenesis during a fast
C. Will have adipose tissue cells that are just as responsive to insulin
D. Will have muscle cells that are just as responsive to insulin
E. Will synthesize more lipoprotein in the fasting state
Answer
Top
16. During a fast, muscle protein is catabolized to free amino acids. All of the following scenarios
occur EXCEPT:
A.
B.
C.
D.
E.
Alanine travels to the liver and is used for gluconeogenesis
Alanine travels to the liver and donates an amino group to the synthesis of urea
Glutamine travels to the kidney where it's amide group is used to buffer the urine
Alanine is used for gluconeogenesis in the muscle
Most amino acids travel to the liver and are used by the liver for gluconeogenesis
Answer
Top
17. Which of the following statements about glutamate is NOT true:
A.
B.
C.
It can be synthesized in the transaminase reaction using alanine as a substrate
It can be synthesized in an aminotransferase reaction using aspartate as a substrate
It can be synthesized by the glutamate dehydrogenase reaction using α-ketoglutarate
and free ammonium ion as substrates
D. It can transfer it's amino group to oxaloacetate in a one step reaction
E. It can transfer it's amino group to citrulline in a one step reaction
Answer
Top
18. The urea cycle is regulated by:
A.
B.
C.
D.
E.
Acetyl CoA
Citrate
Malonyl CoA
N-acetylglutamate
Cytoplasmic carbamoyl phosphate
Answer
Top
19. The carbon structure of this amino acid can be converted in a single enzyme step into an
intermediate in either the TCA cycle or the urea cycle:
A.
B.
C.
D.
E.
Arginine
Citrulline
Aspartate
Glutamate
Glutamine
Answer
Top
20. Which of the following is an essential amino acid:
A.
B.
C.
D.
E.
Alanine
Serine
Tryptophan
Glutamine
Asparagine
Answer
Top
21. Serine is a nonessential amino acid. The precursor in glycolysis or the TCA cycle from which
serine is made is:
A.
B.
Glutamate
Oxaloacetate
C. Pyruvate
D. 3-phosphoglycerate
E. Methionine
Answer
Top
22. All of the following amino acids are glucogenic EXCEPT:
A.
B.
C.
D.
E.
Leucine
Alanine
Glutamate
Phenylalanine
Cystine
Answer
Practice Final Examination : Chapters 4
through 39
Question
Shortcut: 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31,3
2, 33, 34, 35, 36, 37, 38, 39, 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
61 6263 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 9
1 92 93 Home Page
This exam has the same number of questions, same structure, and same number of
Practice Questions as the real Final Examination you will take later. The correct
answer, relative objective, and percent of the class answering each question correctly
is at the end of the examination.
Questions:
1. The pH of a solution is 7.4. If half of the hydrogen ions are removed, the new pH would
be:
A.
B.
C.
D.
E.
7.4
7.2
7.1
7.7
6.4
Answer
Top
2. The pKa for ammonium ion is 9.3. At a blood pH of 7.3, there is:
A.
B.
C.
D.
An equal amount of ammonia and ammonium ion
Ten times more ammonia than ammonium ion
One hundred times more ammonia than ammonium ion
Ten times more ammonium ion than there is ammonia
E. One hundred times more ammonium ion than there is ammonia
Answer
Top
3. Phenobarbital is a weak acid with a pKa = 7.1. Its acid form (protonated form) is readily
reabsorbed from the kidney filtrate into the blood. Its charged form (salt form) is not
reabsorbed from the kidney filtrate into the blood, but rather, finds it way to the urine.
Which of the following would you give to an intoxicated patient in order to remove
phenobarbital from her system? [Hint! Use the Henderson-Hasselbalch equation for
phenobarbital and consider the affect of each of the following.
A.
B.
C.
D.
E.
CO2
Alanine
NH4Cl
NaHCO3
Ascorbic acid
Answer
Top
4. Which of the following do you expect to see in a patient with metabolic acidosis with no
respiratory compensation?
A.
B.
C.
D.
E.
Decrease of [H+] in blood
Decrease of [HCO3-] in blood
Decrease of [H2CO3] in blood
Decrease of pCO2 in blood
Decrease of dissolved CO2 in blood
Answer
Top
5. Refer to the following Figure for Questions 5 and 6. In which row is a structure for
lysolecithin found?
A.
B.
C.
D.
E.
Row A
Row B
Row C
Row D
Row E
Answer
Top
6. Refer to the following Figure for Questions 5 and 6. In which row is a structure for
triacylglycerol found?
A.
B.
C.
D.
E.
Row A
Row B
Row C
Row D
Row E
Answer
Top
Figure for Questions 5 and 6
Question 5, In which row is a structure for lysolecithin found?
Question 6, In which row is a structure for triacylglycerol found?
A = Row A, B = Row B, C = Row C, D = Row D, E = Row E
Top
7. Refer to the following Figure for Question 7. Which answer is correct
A.
B.
C.
D.
E.
Column A shows Adenine and pyrimidine ring
Column B shows Guanine and pyrimidine ring
Column C shows Thymine and pyrimidine ring
Column D shows Niacin and pyrimidine ring
Column C shows Thymine and purine ring
Figure for Question 7
Answer
Top
8. Arichidonic Acid is
A.
B.
C.
D.
E.
is depicted as 16:0
is depicted as 18:0
is depicted as 18:Δ9
is depicted as 18:3Δ9,12, 15
is depicted as 20:4Δ5,8,11,14
Answer
Top
9. This amino acid has three pKa's and an isoelectric point of 3.1. The amino acid is:
A.
B.
C.
D.
E.
Glutamate
Histidine
Methionine
Cysteine
Cystine
Answer
Top
10. Which of the following will migrate the fastest toward the positive end of an electric
field?
A.
B.
C.
D.
E.
Alanine at a pH of 11.0
Arginine at a pH of 10.0
Histidine at a pH of 8.0
Tryptophan at a pH of 5.0
Glutamine at a pH of 1.0
Answer
Top
11. Which of the following best describes the net charge of the R groups of the following
amino acids at the designated pH?
A. Glutamate: Positively charged at a pH of 7.4
B.
C.
D.
E.
Histidine: Positively charged at a pH of 4.1
Lysine: No charge at a pH of 3.8
Aspartate: Negatively charged at a pH of 1.7
Arginine: Negatively charged at a pH of 6.0
Answer
Top
12. What will be the net charge of the protein below at physiologic pH (7.4)?
NH3+-Ala-Phe-Glu-Lys-Arg-Pro-COOA.
B.
C.
D.
E.
+2
0
+1
-1
-2
Answer
Top
13. If a polypeptide portion of a protein can assume the same stable conformation that it
does in the native protein, it can be called a:
A.
B.
C.
D.
E.
Quaternary structure
Mosaic
Motif
Domain
Native Protein
Answer
Top
14. Which of the following characterize the a-helix secondary structure of proteins?
A.
B.
C.
D.
E.
Occur rarely in nature
Involves two antiparallel chains
Includes zinc atoms bound to cysteine and histidine residues
Hydrogen bonds between oxygens and nitrogen atoms four residues apart
Coils rich in proline residues
Answer
Top
15. HbA1C is
A.
B.
C.
D.
E.
hemoglobin electrostatically bound to galactose
synthesized only in the kidney, liver, and pancreas
made by the enzyme glucohemoloobin synthase
made during protein synthesis
a measure of blood glucose during the past 6 weeks
Answer
Top
16. As you read about, Michel Sichel just experienced a sickle cell crisis. Which of the
following statements about sickle cell anemia is TRUE?
A.
B.
C.
D.
E.
Aspartate is substituted for cysteine on HbS subunits
Red blood cells are usually only "sickle" shaped in tissue capillaries
The "anemia" is from an iron deficiency
Amino acid substitution results in a hydrophobic knob or area
"Pain" associated with this disease is from vessel wall injury
Answer
Top
17. When lactate is oxidized to pyruvate:
A.
B.
C.
D.
E.
Two electrons and two protons are transferred to NAD+
Two electrons and two protons are transferred from NAD+
One electron and two protons are transferred to NAD+
One electron and two protons are transferred from NAD+
Two electrons and one protons are transferred to NAD+
Answer
Top
18. The drug allopurinol is used to treat gout. Which of the following common biological
pathways is inhibited by the drug?
A.
B.
C.
D.
E.
The conversion of urate to hypoxanthine
The conversion of urate to xanthine
The conversion of hypoxanthine to inosine monophosphate
The conversion of guanine to guanosine monophosphate
The conversion of GMP to urate
Answer
Top
19. To stabilize the transition state complex, which of the following must be lowered?
A.
B.
C.
D.
E.
Initial energy state
Activation energy
Net energy change
The Vmax
Final energy state
Answer
Top
20. The following enzyme reaction is an example of a(n)?
Glucose + ATP = Glucose-6-phosphate + ADP
A. Oxidoreductase
B. Transferase
C. Hydrolase
D. Lyase
E. Ligase
Answer
Top
21. During muscle contraction, calcium is released from the endoplasmic reticulum. An
increase in glycogenolysis is initiated when calcium binds to
A.
B.
C.
D.
E.
Calmodulin
Troponin I
Protein kinase A
Zymogen
Protein phosphatase
Answer
Top
22. If an enzyme is described by the Michaelis-Menten equation, a competitive inhibitor will:
A.
B.
C.
D.
E.
decrease the Km and decrease the Vmax
decrease the Km, but not the Vmax
always just change the Vmax
increase the Km but not change the Vmax
increase the Km and decrease the Vmax
Answer
Top
23. You have isolated the control enzyme phosphofructokinase-1. When you plot the initial
velocity vs. substrate concentration, an S-shaped curve results. This reflects
A.
B.
C.
D.
E.
competitive inhibition
that an allosteric activator is absent
that the enzyme is phosphorylated
Michaelis-Menten kinetics
cooperative binding
Answer
Top
24. An apoenzyme
A. Includes non-protein compounds such as metal ions
B. Consists of complex organic structures which may be classified as activation-transfer
coenzymes or oxidation-reduction coenzymes
C. Is the protein portion of the enzyme without the cofactors
D. Includes vitamins E and C
E. None of the above
Answer
Top
25. As a result of insulin binding to the insulin receptor, the GRB protein binds to the IRS. The
binding of the GRB adaptor protein occurs because the IRS contains
A.
B.
C.
D.
E.
A phosphorylated tyrosyl residue
A phosphorylated seryl residue
A src homology binding domain (SH2 domain)
Bound inositol trisphosphate
An alpha-1 receptor
Answer
Top
26. When epinephrine binds to alpha-1 receptors, one result is
A.
B.
C.
D.
E.
The receptor binds to the IRS-protein
The receptor inhibits phospholipase-C
The endoplasmic reticulum releases calcium ions
There is a reduction in the diacylglycerol concentration
Calmodulin dissociates from all the proteins to which it normally binds
Answer
Top
27. Concerning Mya Sthenia who has myasthenia gravis, her chemical messenger system
differs from a normal person because she has too
A.
B.
C.
D.
E.
little calcium released near the presynaptic membrane
many inhibitory proteins in the neuromuscular junction
much vesical fusion in the presynaptic junction
much acetylcholine esterase
few acetylcholine receptors in the postsynaptic membrane
Answer
Top
28. When epinephrine binds to a b-receptor on the liver membrane and activates a Gαs signal
transduction protein,
A.
B.
C.
D.
E.
The Gαs protein releases GTP and binds to GDP
The Gαs protein dissociates into an αβ- complex and a γ-subunit
The enzyme adenylyl cyclase is inhibited
Cyclic-AMP and PPi are produced
Protein kinase A is inhibited by cyclic-AMP
Answer
Top
29. Given the following reactions:
A + H20 = B + C
D + H20 = B + G
K + H20 = B + L
J + H20 = B + M
Delta-Go' = + 11 kcal/mol
Delta-Go' = + 3 kcal/mol
Delta-Go' = -7 kcal/mol
Delta-Go' = -5 kcal/mol
Which of these reactions would be exergonic when proceeding from left to right?
A.
B.
C.
D.
E.
A+G=C+D
A+M=C+J
D+M=G+J
A+L=K+C
K+M=J+L
Answer
Top
30. NAD+, FAD, and FMN are all cofactors for:
A.
B.
C.
D.
E.
Oxidoreductases
Transferases
Hydrolases
Lyases
Ligases
Answer
Top
31. All of the following would help to explain why ischemia would cause a failure of the left
ventricular muscle to eject a normal amount of blood EXCEPT:
A.
B.
C.
D.
E.
Without oxygen, the electron transport system is inhibited
Without oxygen, a proton gradient could not be maintained
Without oxygen, an adequate amount of oxidative phosphorylation can not occur
Without oxygen, there will not be enough ATP to cause adequate muscle contraction
Without oxygen, intracellular calcium concentrations cannot be maintained at a high
enough level
Answer
Top
32. For the reaction A = B + C, the concentration of A is 1 mM, the concentration of B is 1
mM and the concentration of C is 2 mM. Also, standard free energy change for the reaction
under biological conditions is Delta-Go' = 0 kcal/mole and free energy change for the reaction
is Delta-G = - 3.7 kcal/mole. If the concentration of C is lowered to 1 mM,
A.
B.
C.
D.
E.
The reaction will be at equilibrium
The reaction will proceed from right to left
The Delta Go' will become more negative
The Delta G will become more negative
The Delta Go' will become more positive
Answer
Top
33. When muscles contract, a chain of events result in greater activity by the TCA cycle. All of
the following are links in that chain EXCEPT:
A. The ADP concentration increases
B.
C.
D.
E.
The proton gradient across the mitochondrial membrane is diminished
The electron transport chain produces more water
The concentration of NADH decreases and the concentration of NAD+ increases
Alpha-ketoglutarate dehydrogenase is inhibited by phosphorylation
Answer
Top
34. The TCA cycle:
A.
B.
C.
D.
E.
Is found in the cytosol
Is controlled by calcium ion, the ADP/ATP ratio, and the NADH concentration
Is also called the Cori cycle
Consumes most of the CO2 produced by ribosomes
Produces most of the water made in humans
Answer
Top
35. Which of the following statements regarding the four "dehydrogenases" of the TCA cycle
is INCORRECT?
A. These are enzymes which remove electrons in the form of hydrogen from various
structures and transfer them to others
B. At least one catalyzes the "rate-limiting steps" of the TCA cycle
C. GTP is generated from one of them via substrate level phosphorylation
D. NAD+ and FAD are the electron-accepting coenzymes for these enzymes
E. At least one catalyzes a reversible reactions
Answer
Top
36. The rate at which pyruvate from glycolysis is used by the TCA cycle to produce energy is
regulated by pyruvate dehydrogenase. During muscle contraction, this enzyme is
A.
B.
C.
D.
E.
Inhibited by increases in the calcium concentration.
Activated by increased in acetyl CoA
Activated by increases in NADH
Activated by increases in ADP
Inhibited by increases in AMP
Answer
Top
37. If a muscle begins to work hard, the ATP concentration of the cell will drop. In turn, the
pyruvate dehydrogenase reaction will be activated. Which of the following mechanisms will
NOT play a role, either directly or indirectly, in this activation?
A.
B.
C.
D.
E.
Increased Ca++ will cause dephosphorylation and activation of the enzyme
Increased ADP will inhibit phosphorylation of the enzyme and activate the enzyme
Increased ADP will activate ATP synthase and lower the proton gradient
A lower proton gradient will increase the utilization of NADH
Increased NADH will activate pyruvate dehydrogenase
Answer
Top
38. The chemiosmotic theory holds all of the following EXCEPT:
A.
B.
C.
D.
The inner mitochondrial membrane is impermeable to protons
The cytosol has a higher pH than the matrix
In the absence of a proton motive force, ATP will not be synthesized
The electrochemical potential comes from both the electrical potential and the
proton concentration gradient
E. Electrons are passed from one carrier to the next as protons are pumped across the
inner mitochondrial membrane
Answer
Top
39. When the electron transport chain is exposed to cyanide,
A.
B.
C.
D.
E.
It becomes uncoupled
More ATP is made
The concentration of NADH increases
The cytochromes are all oxidized
The pumping of protons increases resulting in an increase in the proton gradient.
Answer
Top
40. Which of the following can increase the permeability of membranes to protons and thus
decrease ATP synthesis while increasing the consumption of O2
A.
B.
C.
D.
E.
An inhibitor of cyt a + a3
An inhibitor of complex I
An inhibitor of complex II
An inhibitor of complex III
A proton ionophore
Answer
Top
41. During aerobic glycolysis, the conversion of glucose to pyruvate, what is the net
production of energy in ATP equivalents?
A.
B.
C.
D.
E.
3 ATPs
4 ATPs
5 ATPs
7 ATPs
10 ATPs
Answer
Top
42. You have a patient who eats hard candy throughout the day. The patient also has dental
caries. Which of the following is part of the correlation between eating candy and dental
caries?
A. Glucose from the sucrose is catabolized aerobically by bacteria
B. Aerobic metabolism of glucose produces hydroxyapatite like crystals which are
imperfect
C. Anaerobic metabolism produces pyruvate which is basic and attacks hydroxyapatite
D. Aerobic metabolism produces pyruvate which raises the pH about 9.0. This pH
dissolves teeth
E. Anaerobic metabolism produces lactate and lowers the pH below 5.0. Acid dissolves
bone
Answer
Top
43. When undergoing strenuous exercise the Cori Cycle is functioning. Which of the
following compounds is being delivered to muscle tissue as part of this Cycle?
A.
B.
C.
D.
E.
Glucose
Lactate
Galactose
Pyruvate
Alanine
Answer
Top
44. Anemia, hemorrhage, and chronic obstructive pulmonary disease can all cause metabolic
acidosis. The best explanation is that the lack of oxygen causes
A. a decrease in insulin that, in turn, increases anaerobic glycolysis in the brain
B. a decrease in oxidative phosphorylation so the cells have to rely upon anaerobic
glycolysis
C. a decrease in the oxidation of tyrosine to epinephrine which decreases
gluconeogenesis in muscle
D. a decrease in the removal of CO2 from the blood. The resulting decrease in pH
causes an increase in glycolysis in most cells
E. an increase in glycolysis in red blood cells
Answer
Top
45. All of the following are substrates or products of the fatty acyl CoA synthetase reaction
EXCEPT:
A.
B.
C.
D.
E.
PPi
Acyl CoA
ATP
CoA
ADP
Answer
Top
46. In the fasting state, more ketone bodies are made in the liver because:
A.
B.
C.
D.
E.
Free fatty acid synthesis is increased
Malonyl CoA inhibits carnitine palmitoyl transferase I
The concentration of blood albumin increases
More fatty acid transporters appear on the surface of liver cells
More triacylglycerol is hydrolyzed in adipose cells
Answer
Top
47. Free fatty acids are able to travel from adipose tissue to muscle or liver
A.
B.
C.
D.
E.
As independent water soluble compounds in the blood
By using receptors on red blood cells
Bound to serum proteins
Free fatty acids do not travel to liver
By using enzymes that modify them
Answer
Top
48. Which of the following is NOT TRUE following β-oxidation in the liver?
A. The formation of propionyl CoA could lead to the production of glucose from Boxidation
B. The formation of acetyl CoA could lead to ketone bodies synthesis
C. Acetyl CoA could be converted to pyruvate allowing for the production of glucose
D. Acetyl CoA could be used for the synthesis of HMG CoA
E. Acetyl CoA might be oxidized by the TCA cycle
Answer
Top
49. All other things being constant, an increase in glucagon would result in an increase in
A.
B.
C.
D.
E.
Fatty acid synthesis in adipose tissue
β-oxidation in liver
Malonyl CoA concentrations in liver
Protein synthesis in muscle
Glycogenolysis in muscle
Answer
Top
50. Your patient has an insulinoma. 6 hours after a meal, her blood:
A.
B.
C.
D.
E.
Glucagon would be increased
Free fatty acid concentration would be normal
C-peptide concentration would be increased
Epinephrine concentration would be normal
Concentration of glucose would be normal
Answer
Top
51. Concerning Anne Sullivan who has suffered from NIDDM for five years. Which of the
following statements is true?
A.
B.
C.
D.
E.
Her blood insulin will not be in the normal range
Her β-cells are secreting enough insulin
Her muscle cells are responding normally to insulin
Her adipose cells are responding normally to insulin
Her rate of gluconeogenesis is abnormal
Answer
Top
52. Insulin is secreted by the B-cells of the pancreas into the hepatic portal vein. Which of
the following regarding insulin synthesis is FALSE:
A. The active form of insulin is composed of two polypeptide chains linked by two
interchain disulfide bonds
B. The A-Chain has an intrachain disulfide bond
C. Insulin is synthesized as a preprohormone which is converted to proinsulin
D. Stimulation of A-cells by glucose causes exocytosis of the insulin storage vesicles
E. Cleavage of proinsulin to insulin yields a C-peptide
Answer
Top
53. A woman body builder passed out and went into a coma while lifting weights. When she
arrived at the emergency room, her blood glucose was 24 mg/dL (normal - 70 - 105 mg/dL).
Her friend said that she had injected 60 units of regular (short acting) insulin before each
meal for the last 5 meals. This is at least 4 times normal basal secreting of insulin. Insulin had
all of the following effects EXCEPT:
A.
B.
C.
D.
E.
Increased glucose transport into muscle
Decreased glycogen phosphorylase activity in muscle
Decreased gluconeogenesis in liver
Increased glucose uptake into brain
Decreased glycogen phosphorylase in liver
Answer
Top
54. In liver and muscle, glycogen synthesis is characterized by all of the following EXCEPT:
A.
B.
C.
D.
E.
The phosphorylation of glucose
The formation of UDP-glucose
The actions of the enzyme glycogen synthase, activated by the hormone glucagon
The actions of a branching enzyme, to ensure branching
The conversion of glucose-6-phosphate to glucose-1-phosphate by the enzyme
phosphoglucomutase
Answer
Top
55. Which of the following statements is CORRECT regarding the function of glycogen in liver
and skeletal muscle?
A. In both skeletal muscle and liver, the glucose-6-phosphate formed enters the
glycolytic pathway
B. Glycogen is an important fuel source for skeletal muscle when ATP demands are low
C. Glycogen in skeletal muscle is produced by gluconeogenesis during a prolonged fast
D. Liver glycogen is the first and immediate source of glucose for the maintenance of
blood glucose levels
E. The pathways of glycogenolysis and gluconeogenesis in a liver cell are not activated
together
Answer
Top
56. What is the effect of increases in protein kinase A activity upon the activity of glycogen
synthase and glycogen phosphorylase?
A.
B.
C.
D.
E.
Dephosphorylation and inactivation of glycogen phosphorylase
Phosphorylation and activation of glycogen synthase
Dephosphorylation and activation of glycogen synthase
Phosphorylation and activation of glycogen phosphorylase
Phosphorylation and inactivation of glycogen phosphorylase
Answer
57. The activity of the oxidative portion of the pentose phosphate pathway is controlled by
the:
A.
B.
C.
D.
E.
Cytosolic concentration of ribose-1-phosphate
Mitochondrial concentration of ribose-5-phosphate
Concentration of glyceraldehyde-3-phosphate
Concentration of NADPH in the cytosol
Concentration of NAD+ in the endoplasmic reticulum
Answer
Top
58. NADPH is used for
A.
B.
C.
D.
E.
Oxidizing vitamin C
Oxidizing vitamin E
Oxidizing glutathione
Reductive biosynthesis of fatty acids
β-oxidation of fatty acids
Answer
Top
59. During the Korean War, 10 percent of black servicemen given the drug primaquine
developed drug-induced hemolytic anemia. These men had only 15 percent of the normal
somatic activity of
A.
B.
C.
D.
E.
Glutathione reductase
Phosphoglucoisomerase
Glucose-6-phosphate dehydrogenase
6-phosphogluconate dehydrogenase
Gluconolactonase
Answer
Top
60. All of the following enzymes and metabolites are found in the pathway for the reduction
of HOOH except
A.
B.
C.
D.
E.
6-phosphogluconate dehydrogenase
NADH + H+
Glutathione reductase
Reduced glutathione
Glutathione peroxidase
Answer
Top
61. Liver cells are able to release glucose to the circulation from both glycogen and
gluconeogenesis. Which of the following enzymes is important to both of these processes?
A.
B.
C.
D.
E.
hexokinase
fructose-2, 6-bisphosphatase
glucokinase
glucose-6-phosphatase
fructose-1, 6-bisphosphatase
Answer
Top
62. After strenuous muscle activity, lactate produced from anaerobic glycolysis is recycled in
the liver by being ____________________ in a reaction catalyzed by lactate dehydrogenase.
A.
B.
C.
D.
oxidized by NADH to form oxaloacetate
reduced by NADH to form oxaloacetate
oxidized by NAD+ to form pyruvate
reduced by NAD+ to form pyruvate
Answer
Top
63. A person eats a meal and then watches TV or sleeps for the next 16 hours of a fast. At 16
hours, what is the source of their blood glucose?
A.
B.
C.
D.
E.
100% from gut
100% from gluconeogenesis
100% from glycogenolysis
50% from gut and 50% from gluconeogenesis
50% from glycogenolysis and 50% from gluconeogenesis
Answer
Top
64. Which of the following occurs during prolonged fasting (starvation)?
A. Tissues use the same amount of glucose that they use during a brief fast
B. Blood glucose levels decrease drastically during a four-week fast
C. As a fast progresses, tissues rely predominantly on fuels derived from adipose
triacylglycerols
D. Blood ketone levels decrease dramatically after 3-5 days of fasting
E. After 3-5 days of fasting, the brain increases its utilization of glucose and the rate of
gluconeogenesis and the production of urea increases
Answer
Top
65. Which of the following is an essential fatty acid?
A.
B.
C.
D.
E.
linoleic
palmitic
oleic
stearic
palmitoleic
Answer
Top
66. S-adenosylmethionine is important in the synthesis of
A.
B.
C.
D.
E.
Ethanolamine from diacylglycerol
Phosphatidylcholine from diacylglycerol and CDP-choline
Phosphatidylcholine from phosphatidylethanolamine
Phosphatidylethanolamine from phosphatidylserine
Phosphatidylserine from phosphatidylethanolamine
Answer
Top
67. Palmitoyl CoA and other activated long chain fatty acids can be elongated two carbons at
a time by a series of reactions that occur in the:
A.
B.
C.
D.
E.
Endoplasmic reticulum
Golgi complex
Lysosome
Cytosol
None of the above
Answer
Top
68. An infant is born prematurely and has respiratory distress syndrome. All of the following
will be low EXCEPT
A. Dipalmitoylphosphatidylcholine
B.
C.
D.
E.
Phosphatidyl glycerol
Surface active proteins
Lung surfactant
Sphingomyelin
Answer
Top
69. The pathway for the synthesis of glycogen from portal blood glucose in the liver:
A.
B.
C.
D.
E.
Uses activated hexokinase
Is inhibited by glucose
Is inhibited by insulin
Uses activated glycogen phosphorylase
Is inhibited by high cAMP
Answer
Top
70. A patient with type I diabetes has come to the emergency room with ketoacidosis. All of
her serum samples are opalescent, ie, they scatter light. Compared to a normal person, all of
the following probably contributed to this abnormal serum EXCEPT:
A.
B.
C.
D.
E.
Capillaries don't have as much lipoprotein lipase activity
Adipose hormone sensitive lipase is more active
More VLDL is being synthesized in the liver
The cyclic-AMP concentration of adipose tissue is high
Brain usage of free fatty acids is down
Answer
Top
71. Your patient sufferers from type I diabetes. Compared to a normal person your patient
will have
A.
B.
C.
D.
E.
Less serum lipoproteins
Lower blood glucose
Decreased production of lipoprotein by the liver
Decreased lipoprotein lipase activity
Decreased hormones sensitive lipase activity
Answer
Top
72. The following are all effects of insulin EXCEPT
A.
B.
C.
D.
E.
Stimulation of acetyl CoA carboxylase
Stimulation of the lipolytic activity of hormone sensitive lipase (HSL)
Stimulates adipose cells to synthesize and secrete LPL (lipoprotein lipase)
Stimulates the enzyme glucose-6-phosphate dehydrogenase
Increase in the number of glucose transporters in adipose cell membranes
Answer
Top
73.What is the name of the cofactor for AST, ALT, or any other transamination reaction?
A.
B.
C.
D.
E.
NAD+
Acetyl CoA
Pyridoxal phosphate (PLP)
FADH2
NADPH
Answer
Top
74. Your patient has hepatitis A which has developed into hepatic encephalopathy. All of the
following might be helpful EXCEPT:
A.
B.
C.
D.
E.
Low protein diet
Antibiotics
Lactulose
Enemas
Low carbohydrate diet
Answer
Top
75. Which of the following reactions takes place in the mitochondria during the synthesis of
urea from ammonium ion and glutamate?
A.
B.
C.
D.
Argininosuccinate lyase
Argininosuccinate synthetase
Ornithine transcarbamoylase
Arginase
Answer
Top
76. Alanine aminotransferase (ALT) transfers an amino group from alanine to
A.
B.
C.
D.
E.
Pyruvate
alpha-ketoglutarate
Oxaloacetate
Methionine
Carbamoyl phosphate
Answer
Top
77. Which of the following is an essential amino acid?
A.
B.
C.
D.
E.
Glutamine
Proline
Methionine
Cysteine
Asparagine
Answer
Top
78. You suspect that your 12 year old male patient has an inborn error in methionine
metabolism. His methionine levels are low and his homocysteine levels are high. A liver
biopsy indicates that his cystathionine synthase and cystathionase levels are normal. This
patient may have a deficiency:
A.
B.
C.
D.
E.
Of vitamin B12
Of folic acid
A deficiency in the pathway that synthesizes methyl cobalamin
A deficiency in the pathway that synthesizes N5-methyl tetrahydrofolate
All of the above
Answer
Top
79. The catabolic products of isoleucine, methionine, and valine all enter into the TCA cycle
or glycolysis as
A.
B.
C.
D.
E.
Pyruvate
Oxaloacetate
Succinyl CoA
Acetyl CoA
Fumarate
Answer
Top
80. The patient-has normal cystathionine levels and normal vitamin B12 metabolism. She has
an inborn error in the pathway for tetrahydrofolate production. Which of the following
would be at a lower concentration when compared to a healthy individual?
A.
B.
C.
D.
E.
Methionine
Serine
Cystathionine
Homocystine
Cystine
Answer
Top
81. Ketoacidosis refers to the metabolic acidosis caused by the overproduction of ketoacids.
The classic form of ketoacidosis is uncontrolled diabetes mellitus. All of the following would
occur in a patient suffering from a diabetes-induced metabolic acidosis (diabetic
ketoacidosis) EXCEPT:
A. Deep and/or rapid breathing causes a decrease in the partial pressure of carbon
dioxide (PaCO2) in the blood.
B. The removal of carbon dioxide through deep, rapid breathing results in a rise in the
blood pH
C. When endogenous acid production rises sharply, net acid excretion cannot keep
pace and the bicarbonate lost in buffering is not replaced causing plasma HCO3-levels
to fall
D. Serum bicarbonate levels will decrease after the administration of an insulin
injection
E. The fall in insulin causes fat cells to liberate fatty acids, which flood the hepatocytes
Answer
Top
82. Sickle cell disease results from a point (missense) mutation of the b-globin of:
A.
B.
C.
D.
E.
Glutamine for valine
Valine for glutamate
Hydrophobic amino acid for another hydrophobic amino acid
Hydrophilic amino acid for another hydrophilic amino acid
Hydrophilic amino acid for a hydrophobic amino acid
Answer
Top
83. Aldolase is classified as a(n)
A.
B.
C.
D.
E.
Oxidoreductase
Transferase
Hydrolase
Lyase
Isomerase
Answer
Top
84. When the blood concentration of insulin is increased, less glucagon is produced and
there is an increase in
A.
B.
C.
D.
E.
the activity of adenylate cyclase
the activity of cAMP phosphodiesterase (3’, 5’-phosphodiesterase)
binding of cAMP to the inhibitory subunits of protein kinase A
cAMP
protein kinase A activity
Answer
Top
85. The ΔG and ΔG0! Both refer to the free energy change in a steady state reaction. Steady
state means that the concentrations of substrates and products are fixed or constant. All of
the following statements about ΔG and ΔG0! Are true EXCEPT
A. ΔG refers to a specific reaction with fixed (constant) concentrations of substrate and
products
B. ΔG0! refers to a reaction at pH = 7 and 25 degrees centigrade
C. ΔG0! refers to a reaction with the concentrations of substrates and products, except
hydrogen ion, fixed at one molar concentrations
D. ΔG and ΔG0! can both have positive or negative values
E. ΔG0! for a specific reactions can have many values
Answer
Top
86. Your patient is an alcoholic with a buildup of a-ketoacids and symptoms of wet beriberi.
All of the following might be part of a scenario that would explain why peripheral vessels
dilate and cardiac muscles loose their contractility EXCEPT
A.
B.
C.
D.
E.
Muscle needs ATP to contract
Most ATP is produced by oxidative phosphorylation
NADH and FADH2 are produced by the TCA cycle
The TCA cycle needs thiamine pyrophosphate to function
A shortage of thiamine results in the inability to oxidize NADH
Answer
Top
87. In the muscle, all of the following are part of the pathway whereby increased
epinephrine causes an increase in the glycolytic pathway EXCEPT
A.
B.
C.
D.
E.
Increased binding of GTP to G-protein
Activation of the cAMP cascade
Increased phosphorylation of enzymes by protein kinase A
Activation of fructose-2,6-bisphosphatase and inhibition of phosphofructokinase-2
Increased binding of fructose-2,6-bisphosphate to phosphofructokinase-1
Answer
Top
88. All of the following help to explain the mechanism for releasing insulin from β-cells in
response to the concentration of blood glucose - EXCEPT
A. The important regulator of glycolysis in β cells is the concentration of glucose
reacting with glucokinase
B. ATP is made in proportion to the rate of glycolysis
C. The rate of K+ leaving the cell through a potassium channel is a major determinant of
the polarization of the cell membrane
D. ATP inhibits the K+-channel, the more ATP, the less K+ leaving the cell, and the less
polarized (more depolarized) the cell membrane
E. Depolarization causes Ca++ to exit the cell and insulin leaves the cell through the
insulin transporter
Answer
Top
89. All of the following statements about the pentose phosphate pathway are true EXCEPT
A. Its two functions are to produce NADPH and ribose-5-P
B. It uses glucose-6-P as a substrate when producing NADPH and CO2
C. Glucose-6-phosphate dehydrogenase is the control enzyme and it is regulated by the
NADPH concentration of the cell
D. If it is producing more than twice as much NADPH as ribose-5-P, it can produce
glyceraldehyde-3-P and fructose-6-P
E. It is found in the mitochondria of liver, muscle and brain but is absent from most
other tissues of the body.
Answer
Top
90. The most important control step in gluconeogenesis is fructose-1,6-bisphosphatase. All
of the following statements are true EXCEPT
A. Fructose-1,6-bisphosphatase converts fructose-2,6-bisphosphate to fructose-6phosphate
B. During times when insulin is high, fructose-1,6-bisphosphatase is inhibited by
fructose-2,6-bisphosphate
C. During a fast or exercise when glucagon and/or epinephrine are high, fructose-1,6bisphosphatase is active because of the absence of fructose-2,6-bisphosphate
D. Glycolysis or gluconeogenesis cannot be active at the same time. If they were is
would be a futile cycle
E. In the liver, fructose-2,6-bisphosphate is made by the enzyme phosphofructokinase2. This enzyme is inhibited by the cAMP cascade
Answer
Top
91. When the concentration of epinephrine or glucagon is high, they bind to receptors on
adipose cell membrane and all of the following can be expected to occur EXCEPT
A.
B.
C.
D.
The cAMP cascade activates hormone sensitive lipase
Triacylglycerol is hydrolyzed to free fatty acids and glycerol
Free fatty acids are carried to most tissues of the body by albumin
Fatty acids are activated, enter the mitochondria, and are oxidized by β-oxidation
and the TCA cycle
E. Increased β-oxidation increases glycolysis in resting muscle
Answer
Top
92.This patient has a deficiency of argininosuccinate lyase and has very high concentrations
of blood glutamine and ammonium ion. You could treat her with all of the following EXCEPT
A.
B.
C.
D.
E.
Low protein diet
Arginine supplementation to her diet
Oral doses of hippuric acid and phenylacetylglutamine
Benzoic acid tablets
Oral doses of pheylbutyrate
Answer
Top
93. Your patient has a high serum homocysteine level and a defect in the enzyme that
transfers one-carbon units from N5-methyltetrahydrofolate to form methylcobalamin
(B12). The greatest change from normal would be in the rate of conversion of
A.
B.
C.
D.
E.
Methionine to homocysteine
Homocysteine to methionine
Homocysteine to succinyl CoA
Serine to cysteine
Cysteine to pyruvate and H2SO4