UNIT 3 EXAM - PRACTICE

Question 1

One of the useful tools in diagnosing cancer is called positron emission tomography scan (PET scan). To do the scan, patients would be injected with a safe radioactive-tracet, 2-fluorodeoxyglucose (a glucose analogue shown below), which can be easily visualized under the PET scan as bright yellow/reddish spots. Which statement below does NOT explain cancers bright spots under PET scan?

a. Cancer cells have higher uptake of 2 fluorodeoxyglucose.
b. Cancer cells retain 2-fluorodeoxyglucose inside of the cells likely through phosphorylation.
c. Cancer cells cannot break down 2-fluorodeoxyglucose readily.
d. Cancer cells rapidly convert 2-fluorodeoxyglucose
OH into fluoroacetate for detection.

Answer 1

d. Cancer cells rapidly convert 2-fluorodeoxyglucose
OH into fluoroacetate for detection.

Question 2

If glucose is metabolized according to the Warburg Effect by cancer cells, which reaction best summarizes the overall process?

a. Glucose + 2Pi + 2ADP - Lactate + 2ATP + 2 H2O
b. Glucose + 2Pi + 2ADP -> 2 Lactate + 2ATP + 2 H2O
c. Glucose + 2Pi + 2ADP -> 2 Ethanol + 2AP + 2H2O
d. Glucose + 2Pi + 2ADP - 2 Pyruvate + 2ATP + 2NADH + 2 H20

Answer 2

b. Glucose + 2Pi + 2ADP -> 2 Lactate + 2ATP + 2 H2O

Question 3

Because of Warburg Effect, inhibition of glycolysis is sought after as an anti-cancer therapy.
Which enzyme would be the best target for inhibition from biochemistry point of view?

a. Ketohexokinase
b. Phosphofructose kinase
c. Phosphoglycerate kinase
d. Pyruvate kinase

Answer 3

b. Phosphofructose kinase

Question 4

At first glance, why would the Warburg Effect seem to be unfavourable for cancer cells?

a. Anaerobic metabolism of glucose takes place only in the cytosol, not in the mitochondria.
b. Anaerobic metabolism of glucose produces less energy than aerobic respiration.
c. Anaerobic metabolism of glucose may lead to increase in pH
d. Anaerobic metabolism of glucose may cross-activate other pro-survival cellular pathways.

Answer 4

b. Anaerobic metabolism of glucose produces less energy than aerobic respiration.

Question 5

Why do cancer cells frequently up-regulate glycolysis?

a. To increase energy yield from mitochondria.
b. To inhibit other pro-growth signalling pathways.
c. To produce more metabolic intermediates for biosynthesis.
d. To reduce the rate of pentose phosphate pathway.

Answer 5

c. To produce more metabolic intermediates for biosynthesis.

Question 6

Which one of the following comparisons between glycolysis and gluconeogenesis is WRONG?

a. Glycolysis begins with glucose, but gluconeogenesis may begin with lactate.
b. Glycolysis produces 2 ATP, while gluconeogenesis produces 6 ATP equivalence.
c. Glycolysis takes place in the cytosol, while gluconeogenesis takes place in mitochondria and cytosol.
d. Insulin activates glycolysis, while glucagon activates gluconeogenesis.

Answer 6

b. Glycolysis produces 2 ATP, while gluconeogenesis produces 6 ATP equivalence.

Question 7

How many ATP and NADH molecules are required to synthesize glucose from dihydroxyacetone phosphate (DHAP)?

a. 2 ATP & 2 NADH
b. 2ATP & 0 NADH
c. 0 ATP & 2 NADH
d. 0 ATP & 0 NADH

Answer 7

d. 0 ATP & 0 NADH

Question 8

Which metabolic process produces large amount of glycerol?

a. Glycolysis
b. Gluconcogenesis
c. Lipolysis
d. TCA cycle

Answer 8

c. Lipolysis

Question 9

How many ATP molecules are produced if glycerol is used as fuel for acrobic respiration? (Assume aspartate-malate shuttle is used)

a. 18.5
b. 19.5
c. 17
d. 14.5

Answer 9

a. 18.5

Question 10

Which molecule is NOT a direct product of B-oxidation?

a. FADH2
b. NADH
c. H2O
d. Acetyl CoA

Answer 10

c. H2O

Question 11

Extensive B-oxidation with very limited carbohydrate intake will most likely lead to…

a. Ketoacidosis
b. Ketogenesis
c. Fatty acid synthesis
d. Lactic acidosis

Answer 11

b. Ketogenesis

Question 12

While humans cannot make ecosapentaenoic acid, we can make arachidic acid, a C20:0 saturated fatty acid. How many acetyl Co molecules are needed to make arachidic acid?

a. 20
b. 18
c. 14
d. 10

Answer 12

d. 10

Question 13

Where would the synthesis of arachidic acid take place?

a. In the cytosol
b. In the mitochondrial
c. In the smooth E.R.
d. In the cytosol and smooth E.R.

Answer 13

d. In the cytosol and smooth E.R.

Question 14

To make arachidic acid, how many NADPH molecules are needed?

a. 20
b. 18
c. 14
d. 10

Answer 14

b. 18

Question 15

Which one of the following enzymes is needed to convert arachidic acid into eicosapentaenoic acid?

a. Desaturase
b. Elongase
c. Acyl CoA synthetase
d. Reductase

Answer 15

a. Desaturase

Question 16

Which statement about reduction potential is correct?

a. Reduction potential is directly proportional to the Gibbs free energy.
b. The standard reduction potential is the likelihood that a species will be oxidized.
c. Reactions with the largest positive reduction potential have oxidized forms with the greatest tendency to accept electrons and be reduced.
d. Reactions with most negative reduction potential have oxidized forms with the greatest tendency to accept electrons and be reduced.

Answer 16

c. Reactions with the largest positive reduction potential have oxidized forms with the greatest tendency to accept electrons and be reduced.

Question 17

Which one of the following molecules is most likely to be oxidized?

a. Pyruvate
b. Cytochrome c
c. Lipoic acid
d. O2

Answer 17

c. Lipoic acid

Question 18

What is the net change of reduction potential for the reaction catalyzed by complex IV of the electron transport chain?

a. 0.58 V
b. - 0.58 V
c. 1.05 V
d. - 0.595 V

Answer 18

a. 0.58 V