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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-3-phosphate can be categorized into one of six types of enzymes. This enzyme is most appropriately called a(n):
A. Oxidoreductase
B. Transferase C. Hydrolase D. Lyase E. Isomerase
Answer
Top
2. Diisopropylphosphofluroridate and sarin are mechanism based inhibitors. They form:
A. Weak bonds with enzymes like xanthine oxidase
B. Hydrogen bonds with enzymes like acetylcholinesterase C. Van Der Waals bonds with cyclooxygenase D. Covalent bonds with enzymes like xanthine oxidase E. 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. Curve A
B. Curve B C. Curve C D. Curve 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. Calcitonin
B. Calsequesterin C. Calmodulin D. Calcitriol E. 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. is a Machaelis-Menten substrate
B. it resembles the transition state C. it is a pure carbohydrate D. it is an positive allosteric modifier of the enzyme E. 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. acetone, alcohol dismutase
B. methanol, alcohol kinase C. acetaldehyde, alcohol dehydrogenase D. ketone bodies, NADH E. 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. Prostaglandins
B. Smooth muscle cell membranes C. 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. Hypoxanthine
B. Glycopeptidyl transpeptidase C. Uric acid D. Xanthine oxidase E. Guanine
Answer Top
9. Which of the following statements about allosteric enzymes is CORRECT?
A. The binding of substrate to any active site affects the other active sites B. The plot of initial velocity vs. substrate concentration is a straight line C. The Keq of the reaction is increased when allosteric activator is bound
D. The enzymes contains only one polypeptide chain E. 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. Increase the Vmax
B. Decrease the Vmax C. Increase both the Vmax and the Km D. Decrease both the Vmax and the Km E. Shift the curve to the left
Answer Top
11. Enzymes catalyze reactions by
A. Increasing the free energy of the system so that the change in free energy is positive
B. 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. Usually found in liver
B. Uses fructose as a substrate C. Requires sulfate as a substrate D. Is found everywhere glucokinase is found E. Is inhibited by glucose-6-phosphate
Answer Top
13. cAMP
A. is created by the enzyme phosphodiesterase
B. is destroyed by the enzyme protein kinase A C. is destroyed by the enzyme adenylate cyclase D. will bind to the regulatory subunit of protein kinase A E. increases in concentration whenever insulin is present.
Answer Top
14. Epinephrine binds to α1-receptors in the liver membrane. This binding
A. increases the concentration of phosphatidyl inositol trisphosphate in the membrane
B. activates phospholipase C C. decreases the concentration of diacylglycerol D. increases calcium stored in the endoplasmic reticulum E. 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. decreasing proteolysis in the liver
B. increasing glucagon release from alpha-cells of the pancreas C. decreasing the GTPase activity of Gαs-stimulatory subunit D. decreasing the cAMP phosphodiesterase activity E. increasing protein phosphatase activity in the cell
Answer Top
16. Concerning Mya Sthenia who has myasthenia gravis, she has
A. hypreactive nerves releasing too much epinephrine B. too many epinephrine receptors C. too little active acetylcholineesterase
D. too little acetylcholine E. 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. insulin from beta-cells of the pancreas
B. epinephrine from alpha-cells of the pancreas C. epinephrine from the adrenal medula D. glucagon from the adrenal medula E. 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. adrenalin
B. cortisol C. epinephrine D. insulin E. glucagon
Answer Top
19. In the Ras and MAP kinase pathway, the last step in the pathway is catalyzed by MAP-kinase. MAP-kinase
A. phosphorylates a transcription factor
B. binds to Grb-2 C. activates adenylate cyclase D. activates phospholipase C E. 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. Phosphatidylinositol-3-kinase
B. GRB2 C. Phospholipase C D. MAP Kinase E. 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. Oxidoreductase B. Transferase C. Hydrolase D. Lyase E. Ligase
Answer Top
22. How does the aspirin (acetylsalicylic acid) inhibit prostaglandin endoperoxide synthase (cyclooxygenase)?
A. It acetylates the active site serine
B. It acts as a feed back inhibitor C. It acts as a product inhibitor D. It causes glycosylation of the N-terminus E. It forms a disulfide bond with glycine at the active site
Answer Top
23. Phosphorylase kinase activates muscle glycogen phosphorylase by
A. Converting glycogen phosphorylase a to glycogen phosphorylase b
B. Phosphorylating a seryl residue on glycogen phosphorylase C. Activating protein phosphatase D. Binding to the AMP allosteric binding site E. 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. The MEOS will oxidize more alcohol than the alcohol dehydrogenase enzyme
B. The alcohol dehydrogenase enzyme will oxidize more alcohol than the MEOS system C. The MEOS will reduce more alcohol than the alcohol dehydrogenase enzyme D. The alcohol dehydrogenase enzyme will reduce more alcohol than the MEOS system E. 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. Phosphorylated organic metabolites and hemoglobin
B. Inorganic phosphate and hemoglobin C. Phosphorylated organic metabolites and pyruvate D. Hemoglobin and bicarbonate E. Hemoglobin and albumin
Answer Top
2. The pH of blood changes from normal to 7.25. As a result, the patient will:
A. Breathe more slowly and the carbonic acid concentration will rise
B. Breathe more slowly and the serum bicarbonate concentration will rise C. Breathe more slowly and the pH will rise D. Breathe more quickly and the bicarbonate concentration will rise E. Breathe more 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. higher PaCO2 and higher serum bicarbonate B. lower PaCO2 and higher serum bicarbonate
C. lower PaCO2 and lower serum bicarbonate D. higher PaCO2 and lower serum bicarbonate E. no change in PaCO2 and higher bicarbonate
Answer Top
4. An acid anhydride is formed by removing water from
A. A sulfhydryl group and a carboxylic acid B. An alcohol and a carboxylic acid C. An amino group and a carboxylic acid D. An alcohol group and an inorganic phosphate E. A carboxylic acid and an inorganic phosphate
Answer Top
5. The R-groups of the amino acids valine, leucine, and isoleucine are all:
A. Nonpolar and aromatic
B. Polar and hydrophobic C. Hydrophilic and branched chain D. Polar and charged E. 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. Cystine
B. Histidine C. Lysine D. Asparagine E. Valine
Answer Top
7. At pH of 7, a salt bond would most likely form between the R-groups of:
A. Valine and alanine
B. Histidine and lysine C. Aspartate and arginine D. Arginine and lysine E. Histidine and glutamate
Answer Top
8. Treatment for cystinurea could include:
A. Oxidation of cystine to form 2 cysteine molecules B. Reduction of cystine to form carboxyl groups which would be more soluble C. Reduction of methionine in the diet, since this is a precursor to the synthesis of cysteine
D. Feeding of reduced glutathione, since this will oxidize cystine E. 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. Alpha-helix B. Beta-sheet C. Beta-turn D. Quaternary E. Primary
Answer Top
10. Concerning prion disease, the amyloid protein in the brain is thought to result from
A. The repression of the PrPc gene
B. The accelerated conversion of PrPsc to amino acids C. The raising of the activation energy for the conversion of PrPsc to PrPc D. The raising of the activation energy for the conversion of PrPc to PrPsc E. The 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. The protein contains hydrogen bonds
B. The protein contains a hydrophobic pocket that contains heme C. Imidazole groups stabilize the ferrous ion D. Hydrophobic interactions are partially responsible for the conformation of the molecule E. The protein contains alpha and beta chains
Answer
Top
12. Concerning Di Abietes, HbA1c
A. Measures blood glucose levels since birth
B. Is high when the enzyme hemoglobin glycosylase is active C. Is best used to measure compliance over the last three days D. Is lower if the person lives in a cold climate E. 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. Primary structure B. Secondary structure
C. Tertiary structure D. Quaternary structure E. Motif structure
Answer Top
14. Will Sichel has sickel cell anemia. His beta-chains are changed by the substitution of :
A. a nonpolar valine for a charged glutamate
B. a nonpolar glutamate for a charged valine C. a polar valine for a polar glutamate D. a nonpolar valine for a nonpolar glutamate E. a 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. That the proton concentration is 2 x 10-6
B. That the proton concentration is 2 x 10-8 C. That the proton concentration is 1 x 10-14 D. That this is definitely a buffered solution E. 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. 8 mmol/L
B. 4 mmol/L C. 0.8 mmol/L D. 0.4 mmol/L E. 0.2 mmol/L
Answer Top
17. Which of the following statements about buffers are TRUE?
A. Their effectiveness does not depend upon their concentration
B. Maintenance of blood pH relies solely on the bicarbonate buffering system C. They usually consist of a strong acid and its conjugate base D. Buffers work best when the pH of the solution is within 1 pH unit of its pKa E. 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. 44 mM
B. 22 mM C. 11 mM D. 1.1mM E. 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. sulfhydryl group and a carboxyl group
B. carboxyl group and an amino group C. phosphate group and an alcohol group D. phosphate groupe and a carboxyl group E. 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. Phe - Trp B. Asn - Val C. Glu - Arg
D. Met - Cys E. Ala - Arg
Answer Top
22. Which of the following amino acids has an isoelectric point of about 11
A. Leucine
B. Tryptophan C. Methionine D. Aspartate E. Arginine
Answer Top
23. All of the following are treatments for cystinuria EXCEPT:
A. Increase fluid intake
B. Increased protein in the diet C. Reduce methionine intake in diet D. Sonic fracturing of cystine stones E. 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. Proline
B. Alanine C. Serine D. Isoleucine E. 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. Peptide bonds
B. Disulfide bonds C. Hydrogen bonds D. Salt bonds E. 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. Hb
B. Hb (02) C. Hb (02)2 D. 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. The salt of the acid B. The acid
Answer Top
28. Which of the following statements regarding ligand binding is NOT correct?
A. Some proteins require ligands in order to perform their function
B. Enzymes with their attached ligands are called holoenzymes C. Ligands are synonymous with prosthetic groups D. The heme group on hemoglobin is an example of a tightly bound ligand E. Some apoproteins will bind to ligands
Answer Top
29. Concerning a patient with diabetic ketoacidosis, which compound in her blood reacts with nitroprusside?
A. Glucose
B. Glucose oxidase C. Beta-hydroxybutyrate D. Acetoacetate E. A long chain fatty acid
Answer Top
30. Which of the following is a free radical?
A. N2
B. O2-
C. OH-
D. alanine E. NAD+
Answer Top
31. Regarding any untreated person having diabetes, what level of fasting blood sugar would you expect?
A. 55 mg/dL
B. 70 mg/dl C. 90 mg/dl D. 110 mg/dL E. 126 mg/dL
Answer Top
32. If a person breathes into a paper bag, you would expect their blood CO2 to
A. decrease and their blood pH to increase B. decrease and their blood pH to decrease
C. increase and their blood pH to increase D. increase and their blood pH to decrease E. remain the same because the kidney determines the blood CO2 concentration
Answer Top
33. A thioester is formed by removing water from
A. A sulfhydryl group and a carboxylic acid
B. An alcohol and a carboxylic acid C. An amino group and a carboxylic acid D. An alcohol group and an inorganic phosphate E. 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. Column A
B. Column B C. Column C D. Column D E. Column E
Answer
Figure 1. Top
35. Refer to the structures in Figure 1 above. Which column contains both sorbitol and a ketose?
A. Column A
B. Column B C. Column C D. Column D E. Column E
Answer Top
36. Refer to the structures in Figure 2 below. Which column contains the structure for adenine?
A. Column A B. Column B C. Column C D. Column 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. ΔG
B. ΔGo
C. ΔGo'
D. -TΔS
E. 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. The concentration of D is increased one-hundred fold
B. The concentration of C is increased one-hundred fold
C. The concentration of A is increased one-hundred fold
D. The concentration of B is lowered one-hundred fold
E. The concentration of both A and D are increased one-hundred fold
Answer Top
3. During muscle contraction:
A. ATP binds to the actin-ATPase
B. Low calcium concentration allows interaction of myosin and actin
C. ATP hydrolysis causes necessary changes in conformation
D. Binding of ATP to actin allows association of actin and myosin
E. 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. Catabolism of carbon structures of some amino acids
B. Catabolism of acetate groups from acetyl CoA
C. The production of GTP
D. The production of NADPH
E. 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. Citrate synthase
B. Succinyl CoA synthetase
C. Fumarase
D. Isocitrate dehydrogenase
E. Citrate lyase
Answer Top
8. In contrast to NADH, FAD(2H):
A. Can donate electrons, but only two at a time, in a chemical reaction
B. Has a low affinity for its apoenzyme
C. Is very reactive in solution
D. Is an excellent feedback inhibitor
E. 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. Malate dehydrogenase and fumarase
B. Succinate dehydrogenase and fumarase
C. Succinyl CoA synthetase and succinate dehydrogenase
D. Succinyl CoA synthetase and alpha-ketoglutarate dehydrogenase
E. 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. Thiamin pyrophosphate is a cofactor for pyruvate carboxylase
B. Without thiamin, the TCA cycle produces too much ATP
C. Thiamin is an important intermediate in the electron transport chain
D. Without thiamin, energy cannot be adequately produced by muscle cells
E. 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. On the outer side of the outer mitochondria membrane
B. On the inner side of the outer mitochondria membrane
C. On the outer side of the inner mitochondria membrane
D. On the inner side of the inner mitochondria membrane
E. 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. NADH, Complex I, CoQ, Complex III, Cytochrome C, Complex IV, H2O
B. NADH, Complex I, Complex II, CoQ, Cytochrome C, Complex IV, H2O
C. NADH, Complex II, CoQ, Cytochrome C, Complex III, Complex IV, H2O
D. NADH, Complex I, CoQ, Complex II, Cytochrome C, Complex III, H2O
E. 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. Less heat would be produced
B. Less water would be produced
C. More NADH would be oxidized
D. More ATP would be produced
E. 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. Oxidation-reduction
B. Phosphorylation
C. Acetylation
D. Hydrolysis
E. 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. Contraction of muscle
B. Entry of water into cells through specific pores
C. Phosphorylation of glucose by hexokinase
D. Maintenance of the Na+ and K+ concentration gradients
E. Formation of glycosidic bonds to make glycogen
Answer Top
20. Which of the following is NOT a step during muscle contraction?
A. The terminal end of a myosin filament binds ATP
B. Cleavage of ADP into AMP and Pi provides energy for mechanical work
C. Thick myosin filaments bind thin actin filaments
D. Presence of calcium enables myosin to bind actin
E. ATP is cleaved by an ATPase located on the myosin filament
Answer Top
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. Glucose becomes unstable intracellularly
B. Hexokinase is present
C. ATP hydrolysis
D. High concentration of glucose in the blood compared to cell
E. 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. FAD accepts electrons as the hydrogen atom
B. NADH is the reduced form of the coenzyme
C. FAD(H2) is synthesized from the vitamin riboflavin
D. 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. One of its coenzymes - lipoic acid - comes from the vitamin B-carotene
B. It requires FAD as a coenzyme
C. Carbon dioxide is produced by this complex
D. One of its coenzymes - CoASH - comes from the vitamin pantothenate
E. 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. Citrate synthase
B. a-ketoglutarate dehydrogenase
C. Succiny-CoA synthetase (succinate thiokinase)
D. Malate dehydrogenase
E. 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. Cytochrome Q; NADH dehydrogenase; Cytochrome c; Cytochrome oxidase
B. Complex I; Cytochrome c; Complex II; Cytochrome oxidase
C. NADH dehydrogenase; Cytochrome b-c1; Cytochrome c; Cytochrome oxidase
D. Succinate dehydrogenase; Coenzyme Q; Cytochrome oxidase; Cytochrome c
E. Complex I; Complex II; Coenzyme Q; Cytochrome oxidase
Answer Top
31. All of the following can act as "uncouplers" EXCEPT:
A. Brown adipose tissue
B. Proton ionophores
C. Thermogenin (in infants)
D. Thyroid hormone
E. 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. increase electron flow (flux) through the chain
B. decrease the oxidation of NADH
C. decrease the production of water
D. decrease the pumping of protons across the membrane
E. 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
Calculate the ΔGo′ for the following reaction and determine whether the reaction is
spontaneous
Glucose + ATP --> Glucose-6-P + ADP
A. –10.3 kcal/mol and spontaneous
B. +10.3 kcal/mol and not spontaneous C. –3.7 kcal/mol and not spontaneous D. +3.7 kcal/mol and not spontaneous E. –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. Hexokinase
B. Glucokinase C. Phosphoglycerate kinase D. Pyruvate kinase E. Phosphofructokinase-1
Answer
Top
2. Which of the following is not a component of the Cori cycle:
A. Aerobic glycolysis
B. Blood lactate C. Gluconeogenesis D. Blood glucose E. 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. Low blood CO2
B. Low blood carbonic acid C. High partial pressure of oxygen D. High blood pH E. High blood lactate
Answer Top
4. If palmitoyl CoA undergoes beta-oxidation, the products will be:
A. 8 NADH + 8 FADH2 + 9 Acetyl CoA B. 7 NADH + 7 FADH2 + 8 Acetyl CoA C. 8 NADH + 8 FADH2 + 8 Acetyl CoA D. 7 NADH + 7 FADH2 + 7 Acetyl CoA E. 7 NADH + 7 FADH2 + 6 Acetyl 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. Curve A represents glucose
B. Curve B represents free fatty acid C. Curve B represents acetoacetate D. Curve C represents glucose E. Curve A represents beta-hydroxybutyrate
Answer
Top
6. Medium chain acyl CoA (MCAD) deficiency results in:
A. Increased blood glucose following a meal B. Increased ketone body synthesis during a fast C. Decreased levels of liver ATP during a fast D. Increased gluconeogenesis during a fast E. 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. Fatty acid synthesis in adipose tissue
B. Blood amino acids for gluconeogenesis C. Malonyl CoA concentrations in liver D. Protein synthesis in muscle E. Glycogen synthesis in muscle
Answer Top
8. During the series of events following an increase in insulin, all of the following occur EXCEPT:
A. Insulin binds its receptor, causing the autophosphorylation of receptor subunits
B. Active protein kinases can cause the induction/repression of genes C. Glucagon-stimulated phosphorylation is reversed by the effects of insulin D. Phosphorylation results in more glucose transporters in adipose tissue cells E. 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. The receptor undergoes a change in conformation
B. The receptor autophosphorylates tyrosyl residues C. Phosphorylation of the insulin receptor substrate (IRS) is increased D. More glucose transporters are inserted into the membrane E. 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. The sulfonylurea drug binds to a calcium channel
B. The sulfonylurea drug causes the cell to become more polarized C. The sulfonylurea drug increases the concentration of intracellular calcium D. The sulfonylurea drug inhibits glycolysis in beta-cells E. The sulfonylurea drug inhibits membrane depolarization
Answer Top
11. Which of the following statements about glycogenolysis and glucose metabolism is TRUE?
A. Glucose-6-phosphate from liver glycogen usually enters glycolysis
B. Glucose-6-phosphate from muscle glycogen sometimes enters the blood C. Muscle cytosol contains glucose-6-phosphatase D. Liver glycogenolysis and glycolysis are not usually active at the same time E. 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. Glucokinase produces glucose-6-phosphate B. UDP-glucose pyrophosphorylase produces glucose-1-phosphate
C. Branching enzyme produces alpha-1,4-glucosidic bonds D. ATP is a substrate for glycogen synthase E. Hydrolysis of pyrophosphate makes the overall reaction exergonic
Answer Top
13. All of the following activate muscle phosphorylase EXCEPT:
A. AMP
B. Ca++- calmodulin C. fight or flight D. cyclic-AMP E. protein phosphatase
Answer Top
14. An absence of liver glucose-6-phosphatase is known as:
A. Von Gierke's disease
B. McArdle's disease C. Paget's disease D. Wernicke-Korsakoff syndrome E. 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-3-
phosphate 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-2,6-
bisphosphate
E. Hexokinase; Phosphofructokinase-1; DHAP(dihydroxyacetonephosphate); Phosphoenolpyruvate
Answer Top
16. Which of the following glycolytic enzymes produce ATP during glycolysis
A. Hexokinase
B. Glucokinase C. Phosphofructokinase-1 D. 3-phosphoglycerate kinase E. glyceraldehyde-3-phosphate dehydrogenase
Answer Top
17. The LDH reaction is reversible. Which of the following is not a substrate for this reaction?
A. Lactate B. Pyruvate C. NAD+
D. NADH + H+ E. 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. Aspartate B. Glutamate C. Malate D. Glutamine E. Asparagine
Answer Top
19. The activation of fatty acids involves all of the following players EXCEPT:
A. ATP
B. Fatty acyl CoA synthetase C. Enzyme bound fatty acyl AMP D. Pyrophosphate E. 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. Even chain fatty acids can be completely converted to acetyl CoA
B. The process has four steps, two of which use NAD+ to oxidize the fatty acyl group C. For each NADH that is formed, 2.5 ATP can be generated D. 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. Ketone bodies are synthesized for stored energy during the fed state
B. HMG CoA is an intermediate that is converted into acetoacetate C. Acetoacetate is converted to beta-hydroxybutyrate spontaneously, yielding a CO2 D. Ketone bodies are produced in the brain in response to starvation E. 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. Glucose storage as glycogen in liver and muscle B. Conversion of glucose to triacylglycerols in liver C. Amino acid uptake and protein synthesis in skeletal muscle D. Promotion of the sparing of glucose utilized for energy in the brain during a fast E. 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. The activation of glycogen phosphorylase by insulin
B. The yielding of glucose-1-phosphate residues by the enzyme glycogen phosphorylase C. The activity of a 4: 4- transferase to ensure the debranching D. The activity of an alpha-1,6- glucosidase that yields free glucose residues E. The use of inorganic phosphate by glycogen phosphorylase
Answer Top
27. Which of the following is NOT true?
A. Glucagon causes the breakdown of glycogen in liver to yield glucose to the blood
B. Insulin inhibits glycogenolysis in the liver C. Epinephrine causes the glycogen in liver to be degraded to yield glucose to the blood D. Insulin increases the transport of glucose into muscle cells E. 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. The insulin inhibited glycogenolysis
B. The insulin inhibited gluconeogenesis C. The insulin inhibited hormones sensitive lipase D. The exercise used a lot of glucose E. The 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. ADP
B. AMP C. Carnitine palmitoyltransferase D. Acetyl CoA carboxylase E. 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. More active and more phosphorylated
B. More active and less phosphorylated
C. Less active and more phosphorylated
D. 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. The inhibition of net muscle protein catabolism
B. A decreased concentration of blood amino acids
C. Induction of phosphoenolpyruvate carboxykinase
D. An inhibition of fructose-1,6-bisphosphatase
E. 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. The reduction of antioxidant vitamins
B. Detoxification reactions that use P450
C. The reductive biosynthesis of cholesterol
D. The biosynthesis of palmitate
E. 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. The red blood cells have more active glucose-6-phosphate dehydrogenase
B. The red blood cells have more glutathione reductase activity
C. The red blood cells have more NADH in their cytosol
D. The other cells have less active glucose-6-phosphate dehydrogenase activity
E. 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. Glucose transport into muscle and adipose tissue is increased
B. Glucose uptake and utilization by adipose tissue is increased
C. Glucose storage in glycogen is increased
D. Glycolysis in the liver is increased
E. Glucose uptake by the brain is increased
Answer Top
8. When glucagon binds to a liver cell,
A. G-protein binds to ATP
B. Adenylate cyclase is activated
C. Protein phosphatase is activated
D. Cyclic-AMP is decreased
E. 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. More free fatty acid is mobilized from adipose tissue
B. More glycerol is mobilized from adipose tissue
C. More acetyl CoA is produced from free fatty acid in the liver
D. Acetyl CoA activates pyruvate carboxylase
E. 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. High blood fatty acids
B. Low blood ketone bodies
C. High gluconeogenesis
D. High concentration of active protein kinase A in adipose cells
E. 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. Pyruvate carboxylase
C. Citrate synthase
D. Citrate lyase
E. 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. Dihydroxyacetone phosphate
B. Glycerol-3-phosphate
C. Monoacylglycerol
D. Phosphatidic acid
E. Diacylglycerol
Answer Top
13. Ginny has been fasting (500 kcal/day) for several days. All of the following would
be increased EXCEPT:
A. Cyclic-AMP in adipose tissue
B. The activity of hormone sensitive lipase in adipose tissue
C. The concentration of glycerol phosphate in adipose tissue
D. The amount of free fatty acid bound to albumin in the blood
E. 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. Biotin
B. Thiamine pyrophosphate
C. S-adenosylmethionine
D. Vitamin B12
E. Methylene tetrahydrofolate
Answer Top
15. Which of the following is NOT a glycerophospholipid commonly found in cell
membranes:
A. Phosphatidylglycine
B. Phosphatidylcholine
C. Phosphatidylserine
D. Phosphatidylethanolamine
E. 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. Students 1, 2, and 3 are all correct
B. Students 1 and 2 are both correct and student 3 is incorrect
C. Student 2 is correct and students 1 and 3 are both incorrect
D. Students 1,2,and 3 are all incorrect
E. 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. Mitochondrial pyruvate carboxylase
B. Mitochondrial phosphoenolpyruvate carboxykinase
C. Cytosolic phosphoenolpyruvate carboxykinase
D. Cytosolic pyruvate carboxylase
E. Cytosolic pyruvate kinase
Answer Top
18. When pyruvate carboxylase and phosphoenolpyruvate carboxykinase are active,
futile cycling is prevented by:
A. Phosphorylation and activation of pyruvate kinase by insulin via cAMP
B. Dephosphorylation and inactivation of protein kinase by glucagon via cAMP
C. Phosphorylation and activation of protein kinase by insulin via cAMP
D. 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. The dephosphorylation of pyruvate kinase and an increase in the
B. The phosphorylation of pyruvate kinase and an increase in the
C. The phosphorylation of pyruvate kinase and a decrease in the
D. 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-5-
phosphate, which glycolytic substrate(s) would be most efficient:
A. Glucose-6-phosphate and fructose-1,6-bisphosphate
B. Fructose-6-phosphate and dihydroxyacetone phosphate
C. Glucose-6-phosphate
D. Fructose-6-phosphate and glyceraldehyde-3-phosphate
E. 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. The hydroxyl group of threonine
B. The sulfhydryl group of cysteine
C. The carboxyl group of aspartate
D. The reactive hydrogen of histidine
E. 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. Some glucose is converted to glycerol phosphate
B. Some glucose is stored as glycogen
C. Some glucose is used via aerobic glycolysis
D. Some glucose is used via anaerobic glycolysis
E. 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. An increase in the activity of 3',5'-phosphosdiesterase
B. An increase in the activity of phosphofructokinase-2
C. An increase in the activity of fructose-2,6-bisphosphatase
D. A decrease in the activity of protein kinase
E. 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. Insulin has activated the cyclic AMP cascade in the liver
B. Insulin has activated the cyclic AMP cascade in adipose tissue
C. Insulin has caused an increase in ketone bodies synthesis in the liver
D. Insulin has inhibited fructose-1,6-biphosphatase in the liver
E. Insulin has inhibited glucose uptake and released across the liver cell
membrane
Answer Top
29. Both acetyl CoA and the acyl carrier protein
A. Transfer one carbon units
B. React only with each other
C. Only react when vitamin B12 is present
D. Are synthesized from vitamin thiamine
E. 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. Glycerol
B. Dihydroxyacetone phosphate (DHAP) C. Phosphatidic acid D. Diacylglycerol E. 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. The concentration of free amino acids increases B. The concentration of glycerol increases
C. The concentration of cyclic-AMP rises D. The concentration of fructose-2,6-bisphosphate rises E. The 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. The increased insulin to glucagon ratio activates lipoprotein lipase in adipose tissue B. Increased blood concentrations of free fatty acids bound to albumin C. Inactive acetyl CoA carboxylase D. More flux through beta-oxidation E. 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. Free fatty acids in her blood are too high C. Too much acetyl-CoA is produced by the liver D. Too much hydroxymethylglutaryl CoA is produced E. 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. 1/100
B. 1/10 C. 0 D. 10/1 E. 100/1
Answer Top
5. Which of the following enzyme reactions takes place during the synthesis of urea from ammonium ion and glutamate?
A. Carbamoyl phosphate + citrulline = ornithine
B. Aspartate + citrulline + ATP = argininosuccinate + AMP + PPi C. Argininosuccinate = aspartate + arginine D. CO2 + NH4
+ + 2 ADP = carbamoyl phosphate + 2 ATP E. Argininosuccinate = arginine + urea
Answer Top
6. All of the following would be expected to increase the activity of the urea cycle EXCEPT:
A. Antibiotics B. Switching to a high protein diet
C. Going from the fed state of a normal diet to a fasting state D. An increase in gluconeogenesis E. Stress
Answer Top
7. Which of the following is an essential amino acid?
A. Alanine
B. Glycine C. Valine D. Aspartate E. Serine
Answer Top
8. The products of the catabolism of cysteine are:
A. Serine and phosphate
B. Serine and HCl C. Pyruvate and sulfate D. Serine and sulfate E. Alanine and sulfate
Answer Top
9. All of the following are substrates or products of the phenylalanine hydroxylase reaction EXCEPT:
A. Tetrahydrofolate
B. 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. Methionine
B. Cysteine C. Cystathionine D. α-ketobutyrate E. 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. Tyrosine hydroxylase is absent and lactate dehydrogenase is absent
B. Phenylalanine hydroxylase is absent and aminotransferases are absent C. Tyrosine hydroxylase is present and lactate dehydrogenase is present D. Phenylalanine hydroxylase is present and tyrosine hydroxylase is absent E. Phenylalanine hydroxylase is absent and aminotransferases are present
Answer Top
12. Following a meal, glucose will be stored in liver glycogen because:
A. Hexokinase will be phosphorylated as a result of the high insulin to glucagon ratio B. Hexokinase will be dephosphorylated following a reduction in protein kinase A
C. Glycogen phosphorylase A will be inactivated by phosphorylation by protein kinase A D. Phosphorylase kinase will be inactivated by phosphorylation by protein kinase A E. Glycogen synthase will be activated by protein phosphatase
Answer Top
13. The enzyme acetyl CoA carboxylase is activated following an increase in:
A. Malonyl CoA
B. Protein kinase A activity C. Cyclic AMP D. Palmitoyl CoA E. Proteins phosphatase activity
Answer Top
14. The delivery of free fatty acids from lipoproteins into adipose tissue cells will be increased by:
A. Epinephrine
B. Norepinephrine C. Diabetes D. Glucagon E. Insulin
Answer Top
15. Compared to a normal person, a patient with diabetes Type II:
A. Will release more insulin from her beta cells following the same meal
B. 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. Alanine travels to the liver and is used for gluconeogenesis
B. Alanine travels to the liver and donates an amino group to the synthesis of urea C. Glutamine travels to the kidney where it's amide group is used to buffer the urine D. Alanine is used for gluconeogenesis in the muscle E. 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. It can be synthesized in the transaminase reaction using alanine as a substrate
B. It can be synthesized in an aminotransferase reaction using aspartate as a substrate C. 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. Acetyl CoA B. Citrate C. Malonyl CoA
D. N-acetylglutamate E. 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. Arginine
B. Citrulline C. Aspartate D. Glutamate E. Glutamine
Answer Top
20. Which of the following is an essential amino acid:
A. Alanine
B. Serine C. Tryptophan D. Glutamine E. 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. Glutamate
B. Oxaloacetate
C. Pyruvate D. 3-phosphoglycerate E. Methionine
Answer Top
22. All of the following amino acids are glucogenic EXCEPT:
A. Leucine
B. Alanine C. Glutamate D. Phenylalanine E. 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. 7.4 B. 7.2 C. 7.1 D. 7.7 E. 6.4
Answer Top
2. The pKa for ammonium ion is 9.3. At a blood pH of 7.3, there is:
A. An equal amount of ammonia and ammonium ion B. Ten times more ammonia than ammonium ion C. One hundred times more ammonia than ammonium ion D. 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. CO2 B. Alanine C. NH4Cl D. NaHCO3 E. 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. Decrease of [H+] in blood B. Decrease of [HCO3
-] in blood C. Decrease of [H2CO3] in blood D. Decrease of pCO2 in blood E. 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. Row A B. Row B C. Row C D. Row D E. 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. Row A B. Row B C. Row C D. Row D E. 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. Column A shows Adenine and pyrimidine ring B. Column B shows Guanine and pyrimidine ring C. Column C shows Thymine and pyrimidine ring D. Column D shows Niacin and pyrimidine ring E. Column C shows Thymine and purine ring
Figure for Question 7
Answer
Top
8. Arichidonic Acid is
A. is depicted as 16:0 B. is depicted as 18:0 C. is depicted as 18:Δ9 D. is depicted as 18:3Δ9,12, 15 E. 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. Glutamate B. Histidine C. Methionine D. Cysteine E. Cystine
Answer Top
10. Which of the following will migrate the fastest toward the positive end of an electric field?
A. Alanine at a pH of 11.0 B. Arginine at a pH of 10.0 C. Histidine at a pH of 8.0 D. Tryptophan at a pH of 5.0 E. 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. Histidine: Positively charged at a pH of 4.1 C. Lysine: No charge at a pH of 3.8 D. Aspartate: Negatively charged at a pH of 1.7 E. 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-COO
-
A. +2 B. 0 C. +1 D. -1 E. -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. Quaternary structure B. Mosaic C. Motif D. Domain E. Native Protein
Answer Top
14. Which of the following characterize the a-helix secondary structure of proteins?
A. Occur rarely in nature B. Involves two antiparallel chains C. Includes zinc atoms bound to cysteine and histidine residues D. Hydrogen bonds between oxygens and nitrogen atoms four residues apart E. Coils rich in proline residues
Answer Top
15. HbA1C is
A. hemoglobin electrostatically bound to galactose B. synthesized only in the kidney, liver, and pancreas C. made by the enzyme glucohemoloobin synthase D. made during protein synthesis E. 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. Aspartate is substituted for cysteine on HbS subunits B. Red blood cells are usually only "sickle" shaped in tissue capillaries C. The "anemia" is from an iron deficiency D. Amino acid substitution results in a hydrophobic knob or area E. "Pain" associated with this disease is from vessel wall injury
Answer Top
17. When lactate is oxidized to pyruvate:
A. Two electrons and two protons are transferred to NAD+ B. Two electrons and two protons are transferred from NAD+ C. One electron and two protons are transferred to NAD+ D. One electron and two protons are transferred from NAD+ E. 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. The conversion of urate to hypoxanthine B. The conversion of urate to xanthine C. The conversion of hypoxanthine to inosine monophosphate D. The conversion of guanine to guanosine monophosphate E. The conversion of GMP to urate
Answer Top
19. To stabilize the transition state complex, which of the following must be lowered?
A. Initial energy state B. Activation energy C. Net energy change D. The Vmax E. 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. Calmodulin B. Troponin I C. Protein kinase A D. Zymogen E. Protein phosphatase
Answer Top
22. If an enzyme is described by the Michaelis-Menten equation, a competitive inhibitor will:
A. decrease the Km and decrease the Vmax B. decrease the Km, but not the Vmax C. always just change the Vmax D. increase the Km but not change the Vmax E. 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. competitive inhibition B. that an allosteric activator is absent C. that the enzyme is phosphorylated D. Michaelis-Menten kinetics E. 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. A phosphorylated tyrosyl residue B. A phosphorylated seryl residue C. A src homology binding domain (SH2 domain) D. Bound inositol trisphosphate E. An alpha-1 receptor
Answer Top
26. When epinephrine binds to alpha-1 receptors, one result is
A. The receptor binds to the IRS-protein B. The receptor inhibits phospholipase-C C. The endoplasmic reticulum releases calcium ions D. There is a reduction in the diacylglycerol concentration E. 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. little calcium released near the presynaptic membrane B. many inhibitory proteins in the neuromuscular junction C. much vesical fusion in the presynaptic junction D. much acetylcholine esterase E. 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. The Gαs protein releases GTP and binds to GDP B. The Gαs protein dissociates into an αβ- complex and a γ-subunit C. The enzyme adenylyl cyclase is inhibited D. Cyclic-AMP and PPi are produced E. Protein kinase A is inhibited by cyclic-AMP
Answer Top
29. Given the following reactions:
A + H20 = B + C Delta-Go' = + 11 kcal/mol
D + H20 = B + G Delta-Go' = + 3 kcal/mol
K + H20 = B + L Delta-Go' = -7 kcal/mol
J + H20 = B + M Delta-Go' = -5 kcal/mol
Which of these reactions would be exergonic when proceeding from left to right?
A. A + G = C + D B. A + M = C + J C. D + M = G + J D. A + L = K + C E. K + M = J + L
Answer Top
30. NAD+, FAD, and FMN are all cofactors for:
A. Oxidoreductases B. Transferases C. Hydrolases D. Lyases E. 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. Without oxygen, the electron transport system is inhibited B. Without oxygen, a proton gradient could not be maintained C. Without oxygen, an adequate amount of oxidative phosphorylation can not occur D. Without oxygen, there will not be enough ATP to cause adequate muscle contraction E. 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. The reaction will be at equilibrium B. The reaction will proceed from right to left C. The Delta Go' will become more negative D. The Delta G will become more negative E. 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. The proton gradient across the mitochondrial membrane is diminished C. The electron transport chain produces more water D. The concentration of NADH decreases and the concentration of NAD+ increases E. Alpha-ketoglutarate dehydrogenase is inhibited by phosphorylation
Answer Top
34. The TCA cycle:
A. Is found in the cytosol B. Is controlled by calcium ion, the ADP/ATP ratio, and the NADH concentration C. Is also called the Cori cycle D. Consumes most of the CO2 produced by ribosomes E. 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. Inhibited by increases in the calcium concentration. B. Activated by increased in acetyl CoA C. Activated by increases in NADH D. Activated by increases in ADP E. 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. Increased Ca++ will cause dephosphorylation and activation of the enzyme B. Increased ADP will inhibit phosphorylation of the enzyme and activate the enzyme C. Increased ADP will activate ATP synthase and lower the proton gradient D. A lower proton gradient will increase the utilization of NADH E. Increased NADH will activate pyruvate dehydrogenase
Answer Top
38. The chemiosmotic theory holds all of the following EXCEPT:
A. The inner mitochondrial membrane is impermeable to protons B. The cytosol has a higher pH than the matrix C. In the absence of a proton motive force, ATP will not be synthesized D. 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. It becomes uncoupled B. More ATP is made C. The concentration of NADH increases D. The cytochromes are all oxidized E. 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. An inhibitor of cyt a + a3 B. An inhibitor of complex I C. An inhibitor of complex II D. An inhibitor of complex III E. 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. 3 ATPs B. 4 ATPs C. 5 ATPs D. 7 ATPs E. 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. Glucose B. Lactate C. Galactose D. Pyruvate E. 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. PPi B. Acyl CoA C. ATP D. CoA E. ADP
Answer Top
46. In the fasting state, more ketone bodies are made in the liver because:
A. Free fatty acid synthesis is increased B. Malonyl CoA inhibits carnitine palmitoyl transferase I C. The concentration of blood albumin increases D. More fatty acid transporters appear on the surface of liver cells E. 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. As independent water soluble compounds in the blood B. By using receptors on red blood cells C. Bound to serum proteins D. Free fatty acids do not travel to liver E. 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 B-oxidation
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. Fatty acid synthesis in adipose tissue B. β-oxidation in liver C. Malonyl CoA concentrations in liver D. Protein synthesis in muscle E. Glycogenolysis in muscle
Answer Top
50. Your patient has an insulinoma. 6 hours after a meal, her blood:
A. Glucagon would be increased B. Free fatty acid concentration would be normal C. C-peptide concentration would be increased D. Epinephrine concentration would be normal E. 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. Her blood insulin will not be in the normal range B. Her β-cells are secreting enough insulin C. Her muscle cells are responding normally to insulin D. Her adipose cells are responding normally to insulin E. 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. Increased glucose transport into muscle B. Decreased glycogen phosphorylase activity in muscle C. Decreased gluconeogenesis in liver D. Increased glucose uptake into brain E. Decreased glycogen phosphorylase in liver
Answer Top
54. In liver and muscle, glycogen synthesis is characterized by all of the following EXCEPT:
A. The phosphorylation of glucose B. The formation of UDP-glucose C. The actions of the enzyme glycogen synthase, activated by the hormone glucagon D. The actions of a branching enzyme, to ensure branching E. 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. Dephosphorylation and inactivation of glycogen phosphorylase B. Phosphorylation and activation of glycogen synthase C. Dephosphorylation and activation of glycogen synthase D. Phosphorylation and activation of glycogen phosphorylase E. Phosphorylation and inactivation of glycogen phosphorylase
Answer
57. The activity of the oxidative portion of the pentose phosphate pathway is controlled by
the:
A. Cytosolic concentration of ribose-1-phosphate B. Mitochondrial concentration of ribose-5-phosphate C. Concentration of glyceraldehyde-3-phosphate D. Concentration of NADPH in the cytosol E. Concentration of NAD+ in the endoplasmic reticulum
Answer Top
58. NADPH is used for
A. Oxidizing vitamin C B. Oxidizing vitamin E C. Oxidizing glutathione D. Reductive biosynthesis of fatty acids E. 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. Glutathione reductase B. Phosphoglucoisomerase C. Glucose-6-phosphate dehydrogenase D. 6-phosphogluconate dehydrogenase E. Gluconolactonase
Answer Top
60. All of the following enzymes and metabolites are found in the pathway for the reduction of HOOH except
A. 6-phosphogluconate dehydrogenase B. NADH + H+ C. Glutathione reductase D. Reduced glutathione E. 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. hexokinase B. fructose-2, 6-bisphosphatase C. glucokinase D. glucose-6-phosphatase E. 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. oxidized by NADH to form oxaloacetate B. reduced by NADH to form oxaloacetate C. oxidized by NAD+ to form pyruvate D. 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. 100% from gut B. 100% from gluconeogenesis C. 100% from glycogenolysis D. 50% from gut and 50% from gluconeogenesis E. 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. linoleic B. palmitic C. oleic D. stearic E. palmitoleic
Answer Top
66. S-adenosylmethionine is important in the synthesis of
A. Ethanolamine from diacylglycerol B. Phosphatidylcholine from diacylglycerol and CDP-choline C. Phosphatidylcholine from phosphatidylethanolamine D. Phosphatidylethanolamine from phosphatidylserine E. 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. Endoplasmic reticulum B. Golgi complex C. Lysosome D. Cytosol E. 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. Phosphatidyl glycerol C. Surface active proteins D. Lung surfactant E. Sphingomyelin
Answer Top
69. The pathway for the synthesis of glycogen from portal blood glucose in the liver:
A. Uses activated hexokinase B. Is inhibited by glucose C. Is inhibited by insulin D. Uses activated glycogen phosphorylase E. 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. Capillaries don't have as much lipoprotein lipase activity B. Adipose hormone sensitive lipase is more active C. More VLDL is being synthesized in the liver D. The cyclic-AMP concentration of adipose tissue is high E. 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. Less serum lipoproteins B. Lower blood glucose C. Decreased production of lipoprotein by the liver D. Decreased lipoprotein lipase activity E. Decreased hormones sensitive lipase activity
Answer Top
72. The following are all effects of insulin EXCEPT
A. Stimulation of acetyl CoA carboxylase B. Stimulation of the lipolytic activity of hormone sensitive lipase (HSL) C. Stimulates adipose cells to synthesize and secrete LPL (lipoprotein lipase) D. Stimulates the enzyme glucose-6-phosphate dehydrogenase E. 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. NAD+ B. Acetyl CoA C. Pyridoxal phosphate (PLP) D. FADH2 E. NADPH
Answer Top
74. Your patient has hepatitis A which has developed into hepatic encephalopathy. All of the following might be helpful EXCEPT:
A. Low protein diet B. Antibiotics C. Lactulose D. Enemas E. 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. Argininosuccinate lyase B. Argininosuccinate synthetase C. Ornithine transcarbamoylase D. Arginase
Answer Top
76. Alanine aminotransferase (ALT) transfers an amino group from alanine to
A. Pyruvate B. alpha-ketoglutarate C. Oxaloacetate D. Methionine E. Carbamoyl phosphate
Answer Top
77. Which of the following is an essential amino acid?
A. Glutamine B. Proline C. Methionine D. Cysteine E. 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. Of vitamin B12 B. Of folic acid C. A deficiency in the pathway that synthesizes methyl cobalamin D. A deficiency in the pathway that synthesizes N5-methyl tetrahydrofolate E. 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. Pyruvate B. Oxaloacetate C. Succinyl CoA D. Acetyl CoA E. 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. Methionine B. Serine C. Cystathionine D. Homocystine E. 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. Glutamine for valine B. Valine for glutamate C. Hydrophobic amino acid for another hydrophobic amino acid D. Hydrophilic amino acid for another hydrophilic amino acid E. Hydrophilic amino acid for a hydrophobic amino acid
Answer Top
83. Aldolase is classified as a(n)
A. Oxidoreductase B. Transferase C. Hydrolase D. Lyase E. Isomerase
Answer Top
84. When the blood concentration of insulin is increased, less glucagon is produced and there is an increase in
A. the activity of adenylate cyclase B. the activity of cAMP phosphodiesterase (3’, 5’-phosphodiesterase) C. binding of cAMP to the inhibitory subunits of protein kinase A D. cAMP E. 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. Muscle needs ATP to contract B. Most ATP is produced by oxidative phosphorylation C. NADH and FADH2 are produced by the TCA cycle D. The TCA cycle needs thiamine pyrophosphate to function E. 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. Increased binding of GTP to G-protein B. Activation of the cAMP cascade C. Increased phosphorylation of enzymes by protein kinase A D. Activation of fructose-2,6-bisphosphatase and inhibition of phosphofructokinase-2 E. 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
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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.
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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-6-phosphate
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-1,6-bisphosphatase 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 phosphofructokinase-2. This enzyme is inhibited by the cAMP cascade
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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. The cAMP cascade activates hormone sensitive lipase B. Triacylglycerol is hydrolyzed to free fatty acids and glycerol C. Free fatty acids are carried to most tissues of the body by albumin D. 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
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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. Low protein diet B. Arginine supplementation to her diet C. Oral doses of hippuric acid and phenylacetylglutamine D. Benzoic acid tablets E. Oral doses of pheylbutyrate
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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. Methionine to homocysteine B. Homocysteine to methionine C. Homocysteine to succinyl CoA D. Serine to cysteine E. Cysteine to pyruvate and H2SO4
