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EXAM 3 PRACTICE QUESTIONS
Biochemistry 460
Dr. Canfield Fall 2005
MULTIPLE CHOICE (Only one answer is correct)
1. Most of the enzymes of the citric acid cycle are located in the
a. mitochondrial matrix.
b. inner mitochondrial membrane.
c. intermembrane space.
d. outer mitochondrial membrane.
e. cytosol.
2. Most of the ATP made during cellular respiration is generated by:
a. substrate-level phosphorylation.
b. oxidative phosphorylation.
c. glycolysis.
d. the malate-aspartate shuttle.
3. This reaction uses a cofactor derived from niacin:
a. glyceraldehyde-3-phosphate dehydrogenase
b. succinate dehydrogenase
c. pyruvate carboxylase
d. phosphofructokinase
4. The two monosaccharides that comprise the dissacharide sucrose are:
a. galactose and glucose
b. glucose and maltose
c. glucose and fructose
d. galactose and fructose
5. The respiratory chain complex that does not produce enough energy to pump protons:
a. cytochrome C oxidase
b. succinate Q-reductase
c. cytochrome reductase
d. NADH-Q reductase
6. The enzyme in glyconeogenesis that is unique to the pathway is:
a. phosphoenolpyruvate carboxykinase
b. glyceraldehyde 3-phosphate dehydrogenase
c. pyruvate dehydrogenase
d. enolase
e. phosphoglycerate kinase
7. Isocitrate dehydrogenase in the citric acid cycle is allosterically activated by
a. ATP
b. ADP
c. NADH
d. oxaloacetate
e. succinyl coA
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Exam 3 practice questions
Fall 2005
Dr. Canfield
8. The enzyme that is activated by citrate is
a. glucose 6-phosphatase
b. fructose 1-6 bisphosphatase
c. pyruvate carboxylase
d. fructose 2,6 bisphosphatase
e. phosphoenolpyruvate carboxykinase
9. Hexokinase is allosterically inhibited by:
a. ATP
b. citrate
c. fructose-6-phosphate
d. glucose 6-phosphate
e. phosphorylation
10. Both phosphofructokinase and pyruvate kinase:
a. generate ATP
b. are irreversible reactions
c. use a six carbon substrate
d. are enzymes of gluconeogenesis
11. Glyceraldehyde 3-phosphate dehydrogenase
a. catalyzes the formation of dihydroxyacetone phosphate
b. reduces glyceraldehyde-3-phosphate using NADH as a cofactor
c. produces NADH as a product
d. is an enzyme of the TCA cycle
12. The gluconeogenic enzyme that requires GTP is:
a. glucose 6-phosphatase
b. fructose 1,6 bisphosphatase
c. phosphoglyerate kinase
d. phosphoenolpyruvate carboxykinase
e. acetyl coA carboxylase
13. In the citric acid cycle, FADH2 is formed as a product in a reaction catalyzed by:
a. succinate dehydrogenase
b. citrate synthase
c. malate dehydrogenase
d. succinyl coA synthetase
e. lactate dehydrogenase
14. Most of the enzymes of the electron transport chain are located in the
a. cytosol
b. outer mitochondrial membrane.
c. intermembrane space.
d. inner mitochondrial membrane.
e. mitochondrial matrix.
Exam 3 practice questions
Fall 2005
Dr. Canfield
15. During electron transport, protons are NOT pumped out of the mitochondrion at this site:
a. Complex I.
b. Complex II.
c. Complex III.
d. Complex IV.
16. The cytochrome c oxidase complex
a. accepts electrons from cytochrome c.
a. donates four electrons to O2.
b. produces one molecule H2O per O2 reduced.
c. pumps 4 protons out of the matrix space.
17. The substrate for glycogen synthase is
a. glucose-1-P.
b. glucose-6-P.
c. UDP-glucose.
d. UTP-glucose.
18. The enzyme of gluconeogensis not found in the cytosol:
a. pyruvate carboxylase
b. fructose-1,6-bisphosphatase.
c. glucose-6-phosphatase
d. malate dehydrogenase
19. Fructose-2,6-bisphosphate (F2,6P)
a. inhibits phosphofructokinase.
b. activates fructose-1,6-bisphosphatase.
c. activates phosphofructokinase.
d. inhibits fructose-1,6-bisphosphatase.
20. Epinephrine and glucagon
a. stimulate glycogen phosphorylase by phosphorylation.
b. stimulate glycogen synthase by phosphorylation.
c. stimulate glycogen phosphorylase by dephosphorylation.
d. inhibit glycogen phosphorylase by phosphorylation.
TRUE/FALSE
1. ____Uncoupling of mitochondria decreases the rate of ATP synthesis.
2. ____The reduction potential for reduced coenzyme Q is more negative than the reduction potential for reduced
cytochrome C.
3. ____The enzyme that catalyzes the conversion of phosphoenolpyruvate to pyruvate is activated by
phosphorylation.
4. ____Four protons are pumpted out of the mitochondrial matrix by Succinate Q reductase.
5. ____Hexokinase is the major enzyme that phosphorylates glucose in liver.
6. ____The relaxed form of glycogen phosphorylase is the active form of the enzyme.
7. ____Glycogenin catalyzes the synthesis of UDP glucose from glucose 1-P and UTP
8. ____The active form of glycogen phosphorylase is phosphorylated; the active form of glycogen synthase is
dephosphorylated
9. ____Pyruvate enters the citric acid cycle after being converted to aectyl CoA.
10. ____Covalent reversible modification of key enzymes is an important mechanism for the control of metabolic
pathways.