CHAPTER 24: CARBOHYDRATE METABOLISM
MULTIPLE CHOICE
1. The primary site within the human body where carbohydrate digestion occurs is the: Ans. C
a. mouth
b. stomach
c. small intestine
d. membranes of intestinal mucosal cells
2. Which of the following conversions is accomplished by the process of glycolysis? Ans. B
a. glucose to glycogen
b. glucose to pyruvate
c. starch to glucose
d. pyruvate to glucose
3. The first two intermediates in the process of glycolysis are, respectively,: Ans. C
a. glucose 6-phosphate and glucose 1-phosphate
b. glucose 1-phosphate and glucose 6-phosphate
c. glucose 6-phosphate and fructose 6-phosphate
d. glucose 1-phosphate and fructose 1-phosphate
4. The transition from the C6 stage of glycolysis to the C3 stage involves the conversion of the
molecule fructose 1,6-bisphosphate into the C3 species: Ans. B
a. dihydroxyacetone and glyceraldehydes
b. dihydroxyacetone phosphate and glyceraldehyde 3-phosphate
c. glyceraldehyde and 3-phosphoglycerate
d. 3-phosphoglycerate and 2-phosphoglycerate
5. In the human body, under aerobic conditions and anaerobic conditions, respectively,
pyruvate is converted to: Ans. D
a. lactate and ethanol
b. lactate and acetyl CoA
c. ethanol and lactate
d. acetyl CoA and lactate
6. Accumulation of which of the following substances is the cause of stiff and sore muscles
after vigorous exercise? Ans. A
a. lactate
b. pyruvate
c. acetyl CoA
d. glycerate
7. The net yield of ATP from the complete oxidation of 3 molecules of glucose is: Ans. C
a. 36
b. 72
c. 90
d. 108
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8. The net yield of ATP when 18 glucose molecules are metabolized during the process of
glycolysis only is: Ans. A
a. 36
b. 72
c. 144
d. 216
9. The name of the process in which glucose 6-phosphate is converted to glycogen is: Ans. B
a. gluconeogenesis
b. glycogenesis
c. glycogenolysis
d. glycolysis
10. Which of the following processes requires UTP molecules? Ans. A
a. formation of glycogen from glucose 6-phosphate
b. degradation of glycogen to glucose 6-phosphate
c. both the formation and degradation of glycogen
d. formation of glucose 1-phosphate from glucose 6-phosphate
11. Glycogen is converted to glucose in which of the following processes? Ans. C
a. gluconeogenesis
b. glycogenesis
c. glycogenolysis
d. glycolysis
12. Which of the following intermediates is not involved in glycolysis but is in
gluconeogenesis? Ans. C
a. fructose 6-phosphate
b. pyruvate
c. oxaloacetate
d. acetyl CoA
13. Which of the following is a reactant in the first step of gluconeogenesis? Ans. A
a. carbon dioxide
b. GTP
c. glucose
d. phosphoenolpyruvate
14. Which of the following substances are participants in the reactions encompassed by the Cori
cycle? Ans. B
a. pyruvate and acetyl CoA
b. pyruvate and lactate
c. lactate and acetyl CoA
d. pyruvate, lactate and acetyl CoA
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15. Which of the following hormones promotes the uptake and use of glucose by cells? Ans. A
a. insulin
b. glucagon
c. epinephrine
d. adrenaline
16. Which of the following C6 stage glycolysis intermediates is paired with the correct type of
enzyme needed for its production? Ans. A
a. glucose 6-phosphate; kinase
b. fructose 6-phosphate; dehydrogenase
c. fructose 1,6-bisphosphate; mutase
d. more than one correct response
e. no correct response
17. In which of the following steps of glycolysis does substrate-level phosphorylation occur?
Ans. B
a. production of phosphoenolpyruvate
b. production of pyruvate
c. production of 2-phosphoglycerate
d. more than one correct response
e. no correct response
18. The regeneration of NAD+ from NADH occurs during the conversion of pyruvate to; Ans.
D, a and b
a. lactate
b. ethanol
c. acetyl CoA
d. more than one correct response
e. no correct response
19. Carbon dioxide is a product when pyruvate is converted to: Ans. D, both b and c
a. lactate
b. ethanol
c. acetyl CoA
d. more than one correct response
e. no correct response
20. In which of the following processes is glucose 6-phosphate the end product? Ans. B
a. glycogenesis
b. glycogenolysis
c. glycolysis
d. more than one correct response
e. no correct response
21. The compound glucose 1-phosphate is encountered in which of the following processes?
Ans. A
a. glycogenesis and glycogenolysis
b. glycolysis and gluconeogenesis
c. glycogenesis and gluconeogenesis
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d. more than one correct response
e. no correct response
22. The compound glucose 6-phosphate is not encountered in which of the following processes?
Ans. E
a. conversion of pyruvate to glucose
b. conversion to glucose to pyruvate
c. conversion of glycogen to glucose
d. more than one correct response
e. no correct response
23. The compound oxaloacetate is an intermediate in the conversion of: Ans. B
a. glycogen to glucose
b. pyruvate to glucose
c. pyruvate to acetyl CoA
d. more than one correct response
e. no correct response
24. Which of the following is a product of the pentose phosphate pathway? Ans. D, both b and c
a. carbon dioxide
b. NADPH
c. ribose 5-phosphate
d. more than one correct response
e. no correct response
25. Which of the following hormones increases blood glucose levels? Ans. C
a. insulin and glucagon
b. insulin and epinephrine
c. glucagon and epinephrine
d. more than one correct response
e. no correct response
Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given
statements as being TRUE or FALSE and then indicate the collective true-false status of the
statements using the choices:
a) All three statements are true.
b) Two of the three statements are true.
c) Only one of the statements is true.
d) None of the statements is true.
26.
Statements: Ans. C, only 1 is true
(1) The three major monosaccharide products from carbohydrate digestion are glucose,
galactose, and ribose.
(2) In glycolysis, two ATP molecules are consumed and four ATP molecules are produced.
(3) The Cori cycle is a process in which glucose is converted to pyruvate, which is then
converted back to glucose.
a. All three statements are true.
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b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
27. Statements: Ans. B, both 2 and 3 are true
(1) Glycogenesis and glycolysis are “opposite” processes.
(2) The focal point for carbohydrate metabolism is the molecule glucose.
(3) Production of 30 ATP molecules accompanies the complete oxidation of a glucose
molecule.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
28. Statements: Ans. B, both 2 and 3 are true
(1) Absorption of monosaccharides through the intestinal wall into the bloodstream involves
passive transport.
(2) In the conversion of pyruvate to acetyl CoA, a carbon dioxide molecule is produced.
(3) Glucose degradation occurs in both glycolysis and the pentose phosphate pathway.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
29. Statements: Ans. C, only 2 is true
(1) The process of glycolysis converts a C6 molecule into three C2 molecules.
(2) The primary location where gluconeogenesis occurs is the liver.
(3) Pyruvate reduction to lactate occurs under aerobic conditions, and pyruvate oxidation to
acetyl CoA results from anaerobic conditions.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
30. Statements: Ans. A
(1) Glucose 1-phosphate is an intermediate in both glycogenesis and glycogenolysis.
(2) Conversion of ATP to ADP occurs in both steps one and three of glycolysis.
(3) In the pentose phosphate pathway, a hexose phosphate is converted to a pentose
phosphate and carbon dioxide.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
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31. Statements: Ans. B, only 1 and 2 are true
(1) Gluconeogenesis is a process through which glucose can be synthesized from
noncarbohydrate materials.
(2) The process of glycolysis takes place in the cytosol of a cell.
(3) Insulin's function is to increase blood glucose levels by speeding up the conversion of
glycogen to glucose.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
32. Statements: Ans. A
(1) The conversion of glucose 6-phosphate to glucose does not occur in muscle cells.
(2) The two triose phosphates initially formed in glycolysis are dihydroxyacetone phosphate
and glyceraldehyde 3-phosphate.
(3) ATP production during glycolysis occurs via substrate-level phosphorylation.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
33. Statements: Ans. B, only 1 and 2 are true. The effects are not the same for type I and II
(1) Lactate accumulation is the cause of muscle pain and cramping during prolonged,
strenuous exercise.
(2) Lactate production during exercise lowers blood pH.
(3) The effects of both type I and type II diabetes are the same: inadequate glucose uptake
by cells.
a. All three statements are true.
b. Two of the three statements are true.
c. Only one of the statements is true.
d. None of the statements is true.
NUMERIC RESPONSE
Use the following to answer the questions below:
Assign each of the characterizations to one of the metabolic pathways listed in the response
list. Responses may be used more than once or need not be used at all.
a) gluconeogenesis
b) glycogenesis
c) glycogenolysis
d) glycolysis
1. Glucose is converted to two pyruvates. Ans. D
2. Glycogen is synthesized from glucose 6-phosphate. Ans. B
3. Glycogen is broken down into glucose 6-phosphate units. Ans. C
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4. Glucose is synthesized from pyruvate. Ans. A
5. Two C3 molecules combine to give a C6 molecule. Ans. A
6. Fructose 6-phosphate is the product formed in the second step of this process. Ans. D
7. Formation of UDP-glucose is part of this process. Ans. B
8. Oxaloacetate is the product formed in the first step of this process. Ans. A
9. Two trioses combine to form fructose 1,6-bisphosphate as part of this process. Ans. A
10. Glucose 6-phosphate is converted to glucose 1-phosphate as part of this process. Ans. B
Use the following to answer the questions below:
For each of the chemical changes, choose from the response list a correct name for the
process or the conditions under which it occurs. Responses may be used more than once or
need not be used at all.
a) Cori cycle
b) an anaerobic process
c) pentose phosphate pathway
11. Pyruvate to lactate. Ans. B
12. Pyruvate to ethanol. Ans. B
13. Glucose to pyruvate to lactate to pyruvate to glucose. Ans. A
14. Glucose 6-phosphate to ribose 5-phosphate. Ans. C
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