Chapter 9: Glycolysis: A Paradigm of Metabolic Regulation

1. Metabolism is best defined as a collection of

a. biochemical reactions that convert chemical energy into work.

b. biochemical reactions that convert mechanical energy into work.

c. enzymes that convert glucose into carbon dioxide.

d. enzymes that convert amino acids into proteins.

ANS: A DIF: Easy REF: 9.1

OBJ: 9.1.a. List the major metabolic pathways in animals. MSC: Remembering

2. Catabolic pathways are always paired with anabolic pathways. Why?

a. Catabolic pathways build up new molecules and anabolic break down molecules.

b. Catabolic pathways break down molecules and anabolic build up new molecules.

c. Both require ATP to operate.

d. Both require redox reactions to operate.

ANS: A DIF: Medium REF: 9.1

OBJ: 9.1.c. Distinguish between catabolic pathways and anabolic pathways.

MSC: Analyzing

3. What may be the root cause of the slowing of the flux of metabolites through the glycolysis

and gluconeogenesis pathways in your body?

a. elevated levels of amino acids in the body

b. elevated levels of glycogen in the body

c. lowered levels of protein synthesis

d. lowered levels of enzyme activity

ANS: D DIF: Medium REF: 9.1

OBJ: 9.1.d. Explain how flux through a pathway changes in response to substrate

concentration and enzyme activity. MSC: Evaluating

4. Flux is defined as the rate at which __________ is/are interconverted.

a. enzymes

b. metabolites

c. sugars

d. energy

ANS: B DIF: Easy REF: 9.1

OBJ: 9.1.e. Define metabolic flux. MSC: Remembering

5. In the reaction A→ B, if at equilibrium [B] >> [A], what can be said about the directionality of

the reaction?

a. strongly favored in the forward direction

b. strongly favored in the reverse direction

c. strongly favored in both directions

d. Not enough information is given.

ANS: A DIF: Medium REF: 9.1

OBJ: 9.1.d. Explain how flux through a pathway changes in response to substrate

concentration and enzyme activity. MSC: Applying

6. For the following reaction A→ B, if at equilibrium ΔDG°′ > 0, what can be said about the

directionality of the reaction?

a. strongly favored in the forward direction

b. strongly favored in the reverse direction

c. strongly favored in both directions

d. Not enough information is given.

ANS: B DIF: Medium REF: 9.1

OBJ: 9.1.d. Explain how flux through a pathway changes in response to substrate

concentration and enzyme activity. MSC: Applying

7. How can an unfavorable reaction (ΔG°′ > 0) still occur in a metabolic pathway?

a. Link it to another unfavorable reaction.

b. Link it to a favorable reaction.

c. They cannot be used in metabolic pathway reactions.

d. Increase the temperature of the reaction.

ANS: B DIF: Easy REF: 9.1

OBJ: 9.1.g. Explain how reaction coupling allows an unfavorable ΔG value to be part of a

metabolic pathway. MSC: Understanding

8. Which of the following metabolic pathways is only found in plants?

a. glycolysis

b. citrate cycle

c. photosynthesis

d. urea cycle

ANS: C DIF: Easy REF: 9.1

OBJ: 9.1.b. List the major metabolic pathways in plants. MSC: Remembering

9. Which of the following pathways are found in both plants and animals?

a. photosynthesis and carbon fixation

b. urea cycle

c. nitrogen fixation

d. citrate cycle

ANS: D DIF: Easy REF: 9.1

OBJ: 9.1.b. List the major metabolic pathways in plants. MSC: Remembering

13. Which of the following is an energy conversion pathway?

a. urea cycle

b. citrate cycle

c. nitrogen fixation and assimilation

d. fatty acid degradation and synthesis

ANS: B DIF: Easy REF: 9.1

OBJ: 9.1.f. Distinguish between energy conversion pathways and metabolite synthesis and

degradation pathways. MSC: Understanding

14. What is the main difference between energy conversion pathways and metabolite synthesis

pathways?

a. Energy conversion pathways produce ATP.

b. Energy conversion pathways deplete ATP.

c. Metabolite synthesis pathway uses ATP to break down metabolites.

d. Metabolite synthesis pathway uses ATP to break down pyruvate.

ANS: A DIF: Easy REF: 9.1

OBJ: 9.1.f. Distinguish between energy conversion pathways and metabolite synthesis and

degradation pathways. MSC: Understanding

15. A shared intermediate can be defined as a molecule that is

a. a reactant in a pathway.

b. the final product of a pathway.

c. the final product of a pathway and the reactant of the next

pathway.

d. favorable to produce.

ANS: C DIF: Easy REF: 9.1

OBJ: 9.1.h. Define shared intermediate. MSC: Remembering

17. Which of the following is the correct formula for glucose?

a. C12H22O11

b. C6H12O6

c. C6H6O6

d. C14N2H18O5

ANS: B DIF: Easy REF: 9.2

OBJ: 9.2.a. Distinguish between glucose and fructose. MSC: Remembering

18. Compare the structure of an aldose to a ketose.

a. Ketose has a carbon backbone with an aldehyde group at the end of the molecule,

whereas aldose has a ketone group at the end of the molecule.

b. Ketose has a carbon backbone with a ketone group at the end of the molecule,

whereas aldose has an aldehyde group at the end of the molecule.

c. Both have a carbon backbone where ketose has a ketone group at the end of the

molecule, and aldose also has an aldehyde group at the end of the molecule.

d. Both have a carbon backbone where ketose has a ketone group on the second carbon

in the molecule, and aldose also has an aldehyde group at the end of the molecule.

ANS: D DIF: Medium REF: 9.2

OBJ: 9.2.c. Define aldose and ketose. MSC: Analyzing

19. A chiral center is an atom with

a. two different functional groups and a strong dipole.

b. four different functional groups and which lacks a plane of symmetry.

c. all the same functional groups and a plane of symmetry.

d. the ability to hydrogen bond.

ANS: B DIF: Easy REF: 9.2 OBJ: 9.2.d. Define chiral

center.

MSC: Applying

20. Glucose and fructose are both C6H12O6. What is the structural difference between them?

a. Glucose is a five-membered ring and fructose is a six-membered ring.

b. Fructose is a five-membered ring and glucose is a six-membered ring.

c. Glucose is a linear molecule and fructose is a ring.

d. Glucose is found in the boat conformation and fructose is a chair conformation.

ANS: B DIF: Easy REF: 9.2

OBJ: 9.2.a. Distinguish between glucose and fructose. MSC: Applying

21. Explain the difference between a Fisher projection and a Haworth projection.

a. Fischer projections illustrate the cyclic form, whereas Haworth projections represent

the linear form.

b. The Haworth projection illustrates the six-membered rings, whereas the Fischer

projection represents the five-membered rings.

c. Haworth projections illustrate the cyclic form, whereas Fischer projections represent

the linear form.

d. Fischer projections show the boat conformation, whereas Haworth projections show

the chair conformation.

ANS: C DIF: Medium REF: 9.2

OBJ: 9.2.b. Explain the difference between a Haworth projection and a Fisher projection.

MSC: Applying

22. Define aldose.

a. Only aldose molecules have CH2OH.

b. Aldose molecules have ketone functional groups.

c. Aldose molecules have aldehyde functional groups.

d. Aldose molecules are all five-membered rings.

ANS: C DIF: Easy REF: 9.2

OBJ: 9.2.c. Define aldose and ketose. MSC: Remembering

23. Define ketose.

a. Only ketose molecules have CH2OH.

b. Ketose molecules have ketone functional groups.

c. Ketose molecules have aldehyde functional groups.

d. Ketose molecules are all five-membered rings.

ANS: B DIF: Easy REF: 9.2

OBJ: 9.2.c. Define aldose and ketose. MSC: Remembering

24. Distinguish between D and L isomers.

a. D is right handed and L is left handed.

b. D is left handed and L is right handed.

c. D and L only differ in the position of one chiral center.

d. D is the boat conformation and L is the chair conformation.

ANS: A DIF: Easy REF: 9.2

OBJ: 9.2.e. Distinguish between D and L isomers. MSC: Understanding

26. Anomers differ from each other by changes at the __________ carbon.

a. chiral

b. C-2

c. C-3

d. C-1

ANS: D DIF: Medium REF: 9.2

OBJ: 9.2.f. Differentiate among epimers, anomers, and isomers.

MSC: Understanding

27. Which of following is an anomeric pair?

a. D-glucose and D-fructose

b. D-glucose and L-fructose

c. D-glucose and L-glucose

d. α-D-glucose and β-D-glucose

ANS: D DIF: Medium REF: 9.2

OBJ: 9.2.f. Differentiate among epimers, anomers, and isomers.

MSC: Understanding

28. During the cyclization of D-glucose, where is a new chiral center formed?

a. C-1

b. C-3

c. C-4

d. C-5

ANS: A DIF: Easy REF: 9.2

OBJ: 9.2.g. Demonstrate the cyclization of linear glucose to cyclic glucopyranose.

MSC: Understanding

29. The test using copper to determine blood glucose levels is called a __________ test.

a. glycolysis

b. phosphorylation

c. Benedict's

d. McKee's

ANS: C DIF: Easy REF: 9.2

OBJ: 9.2.h. Explain the significance of Benedict's test. MSC: Remembering

30. A carbohydrate that reacts with oxidizing agents such as Cu+2 is called a(n) __________

sugar.

a. oxidizing

b. reducing

c. rentose

d. aldose

ANS: B DIF: Medium REF: 9.2

OBJ: 9.2.i. Differentiate between a reducing and a nonreducing sugar.

MSC: Remembering

31. Sucrose is a nonreducing sugar. Why?

a. Sucrose does not contain an aldehyde functional group.

b. Sucrose does not react with heat.

c. Sucrose is a pyranose that cannot be reacted with copper.

d. Sucrose is a disaccharide that cannot be converted to an open chain.

ANS: D DIF: Medium REF: 9.2

OBJ: 9.2.i. Differentiate between a reducing and a nonreducing sugar.

MSC: Understanding

34. The glycolytic pathway is responsible for passing molecules to which other pathways?

a. citrate cycle and nitrogen fixation

b. photosynthesis and oxidative phosphorylation

c. citrate cycle and oxidative phosphorylation

d. urea cycle and fatty acid synthesis

ANS: C DIF: Easy REF: 9.3

OBJ: 9.3.a. Describe the glycolytic pathway. MSC: Understanding

35. Which of the following is NOT a reason why glycolysis is considered one of the core

metabolic pathways in nature?

a. Glycolytic enzymes are hugely conserved among all living organisms.

b. It is a primary pathway for ATP generation under anaerobic conditions.

c. Metabolites of glycolysis are precursors for a large number of interdependent

pathways.

d. It is a primary pathway for nitrogen generation.

ANS: D DIF: Easy REF: 9.3

OBJ: 9.3.b. List the three primary reasons why glycolysis is considered one of the core

metabolic pathways in nature. MSC: Understanding

36. Which of the following is the correct net reaction for glycolysis?

a. glucose + 2 ATP → 2 lactate + 2 ADP + 2 Pi

b. glucose + 2 ADP + 2 Pi + 2 NAD+ → 2 pyruvate + 2 ATP + 2 NADH + 4 H+

c. glucose + 2 ADP + 2 Pi → 2 CH3CH2OH + 2 CO2 + 2 ATP

d. glucose + 2 ADP + 2 Pi + 2 NAD+ → 2 pyruvate + 2 ATP + 2 NADH + 2 H+ + 2H2O

ANS: D DIF: Easy REF: 9.3

OBJ: 9.3.d. Identify the overall net reaction of glycolysis. MSC: Understanding

37. What does glycolysis accomplish for the cell?

a. It generates ADP for the cell to be used in other cycles.

b. It generates ATP and pyruvate for the cell to be used in other cycles.

c. It generates glucose to be used for storage.

d. It generates CO2 that is exhaled.

ANS: B DIF: Medium REF: 9.3

OBJ: 9.3.d. Identify the overall net reaction of glycolysis. MSC: Applying

38. In which of the following metabolic conversions is ATP "consumed" during glycolysis?

a. 1,3-Bisphosphoglycerate → 3-phosphoglycerate

b. glucose → glucose-6-phosphate

c. 2-Phosphoglycerate → 3-phosphoglycerate

d. glucose-6-phosphate → fructose-6-phosphate

ANS: B DIF: Medium REF: 9.3

OBJ: 9.3.e. Distinguish between the energy investment of stage 1 and stage 2 of glycolysis.

MSC: Remembering

39. Which of the following best defines substrate-level phosphorylation?

a. direct transfer of a Pi to an ADP

b. direct transfer of a Pi to an ATP

c. indirect transfer of a Pi to an ATP

d. indirect transfer of a Pi to glucose

ANS: A DIF: Medium REF: 9.3

OBJ: 9.3.f. Define substrate-level phosphorylation. MSC: Remembering

40. Which of the following compounds contains a "high-energy" bond and is used to produce ATP

by substrate-level phosphorylation in glycolysis?

a. glucose

b. fructose-1,6-BP

c. 3-phosphoglycerate

d. 1,3-bisphosphoglycerate

ANS: D DIF: Medium REF: 9.3

OBJ: 9.3.f. Define substrate-level phosphorylation. MSC: Applying

41. The first reaction in glycolysis that produces a high-energy compound is catalyzed by

a. aldolase.

b. triose phosphate isomerase.

c. enolase.

d. phosphofructokinase-1.

ANS: D DIF: Easy REF: 9.3

OBJ: 9.3.h. Explain how phosphofructokinase-1 couples ATP hydrolysis with a phosphoryl

transfer reaction. MSC: Remembering

42. Fructose-1,6-bisphosphate is cleaved by aldolase. What is required for the reaction to proceed?

a. production of endergonic intermediate

b. substrate phosphorylation

c. cleaving of high-energy phosphate bond

d. formation of Schiff base intermediate

ANS: D DIF: Medium REF: 9.3

OBJ: 9.3.i. Identify how fructose-1,6-biphosphatase is cleaved by aldolase.

MSC: Understanding

43. Which coenzyme is required to convert glyceraldehyde-3-P into

1,3-bisphosphosphoglycerate?

a. FAD+

b. NAD+

c. ATP

d. Pi

ANS: B DIF: Easy REF: 9.3

OBJ: 9.3.j. Explain how glyceraldehyde-3-P is converted into 1,3-bisphosphoglycerate by

glyceraldehyde-3-P dehydrogenase. MSC: Understanding

44. How does phosphoglycerate kinase make glycolysis energy neutral at this step?

a. It uses ATP to produce 3-phosphoglycerate.

b. It produces 2 ATP along with 3-phosphoglycerate.

c. It results in a reaction at equilibrium.

d. It results in a reaction is endergonic.

ANS: B DIF: Medium REF: 9.3

OBJ: 9.3.k. Describe how phosphoglycerate kinase replaces 2 ATP previously invested in

glycolysis. MSC: Applying

45. What advantage is there to phosphoglycerate kinase having an open and closed configuration?

a. It allows water to be trapped in the active site along with the substrate.

b. It forces covalent binding of the substrate to the enzyme active site.

c. The induced-fit mechanism maximizes accessibility of active site without sacrificing

hydrophobic environment.

d. Changing of the configuration of the enzyme makes the reaction exergonic.

ANS: C DIF: Medium REF: 9.3

OBJ: 9.3.k. Describe how phosphoglycerate kinase replaces 2 ATP previously invested in

glycolysis. MSC: Applying

46. Predict how oxygen saturation would be affected if an individual has defective hexokinase

enzymes.

a. 2,3-BPG levels are elevated and oxygen binding decreases.

b. 2,3-BPG levels are reduced and oxygen binding increases.

c. 2,3-BPG levels are elevated and oxygen binding increases.

d. 2,3-BPG levels are reduced and oxygen binding decreases.

ANS: B DIF: Difficult REF: 9.3

OBJ: 9.3.l. Explain why individuals with defects in glycolytic enzymes have altered

oxygen-transport capabilities. MSC: Applying

47. The enzyme phosphoglycerate mutase operates at ΔG ≈ 0 kJ/mol. That indicates that the

reversibility of that reaction

a. is spontaneous.

b. occurs rapidly.

c. occurs at equilibrium.

d. is nonspontaneous.

ANS: C DIF: Easy REF: 9.3

OBJ: 9.3.m. Demonstrate how phosphoglycerate mutase is a reversible reaction.

MSC: Applying

49. To produce 4 ATP requires 122 kJ/mol. Which reactions in the glycolytic pathway produce

enough energy to be able to overcome this deficit?

a. hexokinase, phosphofructokinase-1, and pyruvate kinase

b. hexokinase, phosphofructokinase-1, and pyruvate kinase

c. phosphofructokinase-1, aldolase, and pyruvate kinase

d. hexokinase, enolase, and pyruvate kinase

ANS: B DIF: Easy REF: 9.3

OBJ: 9.3.n. Demonstrate using Gibbs free energy that glycolysis is an overall favorable

reaction pathway. MSC: Applying

50. Which of the following metabolic conversions is considered to be the major control point of

glycolysis?

a. fructose-1,6-bisphosphate → dihydroxyacetone phosphate +

glyceraldehyde-3-phosphate

b. 1,3-Bisphosphoglycerate + ADP → 3-Phosphoglycerate + ATP

c. 2-phosphoglyerate → phosphoenolpyruvate

d. fructose-6-phosphate → fructose-1,6-bisphosphate

ANS: D DIF: Medium REF: 9.3

OBJ: 9.3.g. List the three irreversible enzymatic reactions in glycolysis.

MSC: Applying

51. In glycolysis, fructose 1,6-bisphosphate is converted to two products with a standard

free-energy change (ΔG′°) of 23.8 kJ/mol. Under what conditions (encountered in

erythrocytes) will the free-energy change (ΔG) be negative, enabling the reaction to proceed

to products?

a. The free-energy change will be negative if the concentrations of the two products are

high relative to that of fructose 1,6-bisphosphate.

b. The reaction will not go to the right spontaneously under any conditions because the

ΔG′° is positive.

c. Under standard conditions, enough energy is released to drive the reaction to the

right.

d. The free-energy change will be negative when there is a high concentration of

fructose 1,6-bisphosphate relative to the concentration of products.

ANS: D DIF: Difficult REF: 9.3

OBJ: 9.3.n. Demonstrate using Gibbs free energy that glycolysis is an overall favorable

reaction pathway. MSC: Analyzing

52. Where in the body is glucokinase found?

a. small intestine

b. liver

c. heart

d. thyroid

ANS: B DIF: Easy REF: 9.4

OBJ: 9.4.a. Explain the role of glucokinase in regulation of the glycolytic pathway.

MSC: Remembering

53. Hexokinase has a Km of 0.1 mM for glucose, whereas glucokinase has a Km of 10 mM for

glucose. What does that mean for their relative affinities for glucose?

a. Glucokinase has a higher affinity.

b. Hexokinase has a higher affinity.

c. Km does not measure affinity.

d. They are different enzymes and affinity cannot be compared between enzymes.

ANS: B DIF: Easy REF: 9.4

OBJ: 9.4.a. Explain the role of glucokinase in regulation of the glycolytic pathway.

MSC: Understanding

54. If blood glucose levels are elevated, what does glucokinase do in response?

a. inhibits glycolysis

b. stimulates the production of more hexokinase

c. stimulates the release of insulin

d. inhibits production of 2,3-BPG

ANS: C DIF: Medium REF: 9.4

OBJ: 9.4.a. Explain the role of glucokinase in regulation of the glycolytic pathway.

MSC: Understanding

55. If you are unable to digest milk products, what is the metabolic root of that issue?

a. maltase

b. lactase

c. sucrose

d. glucose oxidase

ANS: B DIF: Easy REF: 9.4

OBJ: 9.4.g. Describe metabolic roots of lactose intolerance. MSC: Understanding

56. In the presence of lactase, lactose is cleaved into the monosaccharides glucose and

a. glucose.

b. fructose.

c. galactose.

d. maltose.

ANS: C DIF: Easy REF: 9.4

OBJ: 9.4.g. Describe metabolic roots of lactose intolerance. MSC: Understanding

57. The rate limiting step can be defined as a level of enzyme activity that can be regulated to be

__________ even when substrate levels are __________.

a. high; high

b. low; high

c. high; low

d. low; low

ANS: B DIF: Easy REF: 9.4

OBJ: 9.4.c. Define rate limiting step. MSC: Remembering

58. What effect do elevated levels of ATP have on glycolysis?

a. decrease the affinity of PFK-1 for fructose-6-P and slow rate of the pathway

b. increase the affinity of PFK-1 for fructose-6-P and increase the rate of the pathway

c. increase the concentration of PFK-1 in the R-state

d. increase the concentration of glucose entering glycolysis

ANS: A DIF: Medium REF: 9.4

OBJ: 9.4.b. Explain how the conversion of phosphofructokinase-1 between the T and R state

is allosterically controlled by ATP, ADP, and AMP. MSC: Understanding

59. In the presence of high concentrations of ADP and F6P, how does the equilibrium shift

between the T state and R state of PFK-1? High concentrations of ADP and F6P

a. shift equilibrium to the R state.

b. shift equilibrium to the T state.

c. do not bind to PFK.

d. dancel each other out and have no effect.

ANS: A DIF: Medium REF: 9.4

OBJ: 9.4.b. Explain how the conversion of phosphofructokinase-1 between the T and R state

is allosterically controlled by ATP, ADP, and AMP. MSC: Applying

60. If a person has a deficiency in fructose-1-P, what effects does that have on the body?

a. Fructose-6-P concentrations increase.

b. Fructose-6-P is depleted.

c. ATP concentrations increase.

d. Glucose-6-P concentrations increase.

ANS: A DIF: Difficult REF: 9.4

OBJ: 9.4.b. Explain how the conversion of phosphofructokinase-1 between the T and R state

is allosterically controlled by ATP, ADP and AMP. MSC: Applying

61. List three ways in which flux is controlled through glycolysis.

a. regulation of aldolase, PFK-1, and supply and demand of intermediates

b. regulation of glucokinase, fructokinase, and number of intermediates

c. regulation of glucokinase, PFK-1, and concentration of glucose

d. regulation of glucokinase, PFK-1, and supply and demand of intermediates

ANS: D DIF: Difficult REF: 9.4

OBJ: 9.4.d. List three ways in which substrate availability and enzyme activity levels control

flux through the glycolytic pathway. MSC: Applying

62. Galactosemia is deficiency in which enzyme?

a. galactokinase

b. galactose-1-P uridyltransferase

c. UDP-galactose 4-epimerase

d. phosphoglucomutase

ANS: B DIF: Difficult REF: 9.4

OBJ: 9.4.i. Describe the effect of defective galactose-1-P uridylyltransferase.

MSC: Understanding

63. An infant who obtains nourishment from milk and who has galactosemia is unable to convert

a. galactose-1-P to glucose-6-P.

b. glucose-6-P to galactose-1-P.

c. galactose-1-P to glucose-1-P.

d. glucose-1-P to galactose-1-P.

ANS: C DIF: Difficult REF: 9.4

OBJ: 9.4.i. Describe the effect of defective galactose-1-P uridylyltransferase.

MSC: Applying

64. Glucokinase is a molecular sensor for which molecule?

a. glucose

b. lactose

c. galactose

d. maltose

ANS: A DIF: Easy REF: 9.4

OBJ: 9.4.e. Explain why glucokinase is a molecular sensor. MSC: Remembering

65. Which enzyme is the main regulator of glycolysis?

a. hexokinase

b. PFK-1

c. pyruvate kinase

d. aldolase

ANS: B DIF: Easy REF: 9.4

OBJ: 9.4.f. List the allosteric activators and inhibitors of phosphofructokinase-1.

MSC: Understanding

66. What is the potential metabolic fate of pyruvate under aerobic conditions?

a. produce lactate

b. produce ethanol

c. produce carbon dioxide and water

d. produce glucose

ANS: C DIF: Easy REF: 9.5

OBJ: 9.5.a. List the potential metabolic fates of pyruvate. MSC: Understanding

67. What is the potential metabolic fate of pyruvate during strenuous exercise?

a. produce lactate

b. produce ethanol

c. produce carbon dioxide and water

d. produce glucose

ANS: A DIF: Medium REF: 9.5

OBJ: 9.5.a. List the potential metabolic fates of pyruvate. MSC: Understanding

68. The NADH that is produced by glycolysis under anaerobic conditions is regenerated to NAD+

by the conversion of

a. acetaldehyde → ethanol.

b. lactate → pyruvate.

c. phosphoenolpyruvate → pyruvate.

d. pyruvate → lactate.

ANS: D DIF: Medium REF: 9.5

OBJ: 9.5.a. List the potential metabolic fates of pyruvate. MSC: Applying

69. What would the effect be of a lack of lactate dehydrogenase?

a. buildup of glucose

b. buildup of CO2

c. deficiency of ATP

d. deficiency of pyruvate

ANS: C DIF: Medium REF: 9.5

OBJ: 9.5.a. List the potential metabolic fates of pyruvate. MSC: Understanding

70. What is the fate of pyruvate in the presence of yeast, Saccharomyces cerevisiae?

a. converts to CO2 and ethanol

b. converts to H2O and CO2

c. converts to lactate and ethanol

d. converts to lactate and glucose

ANS: A DIF: Medium REF: 9.5

OBJ: 9.5.a. List the potential metabolic fates of pyruvate. MSC: Applying

71. Which of these cofactors participates directly in MOST of the redox reactions in the

fermentation of glucose to lactate?

a. ADP

b. ATP

c. NAD+/NADH

d. FAD/FADH2

ANS: C DIF: Medium REF: 9.5

OBJ: 9.5.a. List the potential metabolic fates of pyruvate. MSC: Remembering

72. When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the

enzyme phosphohexose isomerase, the final mixture contains twice as much glucose

6-phosphate as fructose 6-phosphate. Which one of the following statements is MOST

correct, when applied to the reaction below (R = 8.315 J/mol·K and T = 298 K)?

Glucose 6-phosphate ↔ fructose 6-phosphate

a. ΔG′° is +1.7 kJ/mol.

b. ΔG′° is -1.7 kJ/mol.

c. ΔG′° is zero.

d. It is not possible to calculate ΔG′°

ANS: A DIF: Difficult REF: 9.3

OBJ: 9.3.n. Demonstrate using Gibbs free energy that glycolysis is an overall favorable

reaction pathway. MSC: Applying

73. Fructose 1,6-bisphosphate is converted to two products with a standard free energy of 23.8

kJ/mol. Under what condition(s) will this reaction become spontaneous?

a. spontaneous under any conditions

b. spontaneous under all conditions

c. when there is a high concentration of products relative to the concentration of

fructose 1,6-bisphosphate

d. when there is a low concentration of products relative to the concentration of

fructose 1,6-bisphosphate

ANS: D DIF: Medium REF: 9.3

OBJ: 9.3.n. Demonstrate using Gibbs free energy that glycolysis is an overall favorable

reaction pathway. MSC: Applying

74. During glycolysis, the steps between glucose and formation of glyceraldehyde-3-phosphate

a. consume 2 ATP and 2 NADH.

b. consume 2 ATP.

c. produce 2 ADP and 2 NADH.

d. produce 2 ATP and 2 NADH.

ANS: B DIF: Easy REF: 9.3

OBJ: 9.3.e. Distinguish between the energy investment of stage 1 and stage 2 of glycolysis.

MSC: Applying

75. Which reaction in glycolysis is a redox reaction?

a. glyceraldehyde-3-P → 1,3-bisphosphoglycerate

b. glucose → glucose-6-P

c. 2-phosphoglycerate → phosphoenolpyruvate

d. fructose-6-P → fructose-1,6-BP

ANS: A DIF: Easy REF: 9.3

OBJ: 9.3.a. Describe the glycolytic pathway. MSC: Understanding