Carbohydrate, Lipid, and Protein – Complete Test Bank | Ch24

General, Organic and Biological Chemistry, 4e (Smith)

Chapter 24 Carbohydrate, Lipid, and Protein Metabolism

1) Glycolysis converts ________.

A) polysaccharides to glucose

B) glucose to pyruvate, which is then metabolized to acetyl CoA

C) fatty acids to thioesters, which are then metabolized to acetyl CoA

D) amino acids to urea

2) Which class(es) of compounds generates pyruvate as it is metabolized to acetyl CoA?

A) Only fatty acids

B) Only proteins

C) Only carbohydrates

D) Proteins and carbohydrates

E) Fatty acids, proteins, and carbohydrates

3) Which enzyme is capable of catalyzing the reaction shown?

A) Propanol kinase

B) Propanol isomerase

C) Propanol dehydrogenase

D) Propanol carboxylase

4) Which is not one of the three major products formed in glycolysis?

A) Glucose

B) ATP

C) NADH

D) Pyruvate

5) Which compound can rise to dangerously high levels in individuals with galactosemia?

A) Galactase

B) Glucose 1-phosphate

C) Galactose

D) Galactose 6-phosphate

6) How is pyruvate converted to acetyl CoA?

A) Under aerobic conditions

B) Under anaerobic conditions

C) During fermentation

D) This conversion is favorable under all of the conditions.

7) Which food product does not rely on fermentation for its production?

A) Cheese

B) Beer

C) Yogurt

D) Yeast bread

E) All of the food products listed rely on fermentation for their production.

8) How much ATP results from the transformation of two (2) molecules of acetyl CoA to four (4) molecules of CO2?

A) 2 ATP molecules

B) 5 ATP molecules

C) 12 ATP molecules

D) 20 ATP molecules

E) 32 ATP molecules

9) How much ATP results from the transformation of one glucose molecule to two (2) molecules of acetyl CoA?

A) 2 ATP molecules

B) 5 ATP molecules

C) 12 ATP molecules

D) 20 ATP molecules

E) 32 ATP molecules

10) What is the starting material in step [1] in gluconeogenesis?

A) Glucose

B) Galactose

C) Pyruvate

D) Lactate

E) Acetyl CoA

11) In the Cori cycle, compounds are cycled ________.

A) from the muscles to the kidneys and back to the muscles

B) from the muscles to the liver and back to the muscles

C) from the kidneys to the liver and back to the kidneys

D) from the liver to the brain and back to the liver

12) Which is not a step in the Cori cycle?

A) The catabolism of glucose in muscle forms pyruvate, which is reduced to lactate when the oxygen supply is limited.

B) Lactate is transported to the liver.

C) Oxidation of lactate forms pyruvate, which is then converted to glucose by the 10-step process of gluconeogenesis.

D) Pyruvate and NAD+ are transported to the muscle.

13) Which statement best describes the energy requirement for the conversion of a fatty acid to a thioester with coenzyme A in the β-oxidation of a fatty acid?

A) This process requires energy.

B) This process is energy neutral—energy is neither required nor released.

C) This process releases energy.

D) Whether energy is required or released depends on the identity of the fatty acid being oxidized.

14) β-Oxidation of a fatty acid requires how many steps to cleave a two carbon acetyl CoA unit from the starting acyl CoA?

A) 2

B) 4

C) 8

D) 10

E) The number of steps required is dependent on the identity of the starting acyl CoA.

15) The β-oxidation of a fatty acid may be described as which type of metabolic pathway?

A) An anabolic pathway

B) A cyclic pathway

C) A spiral pathway

D) A linear pathway

16) How many cycles of β-oxidation are needed for complete catabolism of a saturated fatty acid with the chemical formula CH3(CH2)18CO2H?

A) 1

B) 9

C) 10

D) 18

E) 20

17) How many molecules of coenzyme A are needed for complete catabolism of a saturated fatty acid with the chemical formula CH3(CH2)18CO2H?

A) 1

B) 9

C) 10

D) 18

E) 20

18) How many molecules of NADH are formed during the complete catabolism of a saturated fatty acid with the chemical formula CH3(CH2)20CO2H?

A) 1

B) 10

C) 11

D) 20

E) 22

19) How many molecules of ATP are formed during the complete catabolism of a saturated fatty acid with the chemical formula CH3(CH2)20CO2H?

A) 32

B) 98

C) 140

D) 148

E) 150

20) How many moles of ATP per gram of fatty acid are formed during the complete catabolism of a saturated fatty acid with the chemical formula CH3(CH2)24CO2H (molar mass 397 g/mol)?

A) 0.0806 moles ATP / g fatty acid

B) 0.297 moles ATP / g fatty acid

C) 0.423 moles ATP / g fatty acid

D) 0.443 moles ATP / g fatty acid

E) 0.448 moles ATP / g fatty acid

21) How many molecules of ATP are formed per carbon atom in the fatty acid during the complete catabolism of a saturated fatty acid with the chemical formula CH3(CH2)24CO2H?

A) 1.23 molecules ATP / carbon atom in the fatty acid

B) 4.54 molecules ATP / carbon atom in the fatty acid

C) 6.46 molecules ATP / carbon atom in the fatty acid

D) 6.77 molecules ATP / carbon atom in the fatty acid

E) 6.85 molecules ATP / carbon atom in the fatty acid

22) What are the four reactions involved in beta-oxidation in the correct order?

A) Oxidation, hydration, cleavage, oxidation

B) Hydration, oxidation, oxidation, cleavage

C) Oxidation, oxidation, cleavage, hydration

D) Oxidation, hydration, oxidation, cleavage

23) Each four-step sequence of beta-oxidation forms one molecule each of which of the following?

A) Acetyl CoA, NADH, and FADH2

B) Pyruvate, NAD+, and FAD

C) Glucose, NAD+, and FADH2.

D) Acetyl CoA, NADH, and FAD.

24) Which compound is not a ketone body?

A) Acetoacetate

B) Acetone

C) β-hydroxybutyrate

D) Acetyl CoA

25) Which condition does not lead to increased levels of ketone bodies?

A) Uncontrolled diabetes

B) Starvation

C) High carbohydrate diet

D) All of the conditions result in increased levels of ketone bodies.

26) Which compound is necessary for the oxidative deamination of the glutamate formed by transamination?

A) acetyl CoA

B) ATP

C) NADH

D) NAD+

E) FADH2

27) Where does gluconeogenesis take place?

A) In the brain

B) In the muscle tissue

C) In the liver

D) In the kidney

E) Gluconeogenesis takes place in all of the locations listed.

28) What are the products formed in the transamination reaction shown?

A)

B)

C)

D)

29) What product(s) is formed in a transamination reaction?

A) An amino acid

B) Urea

C) Ammonia

D) An α-keto acid

E) An amino acid and an α-keto acid are both formed

30) Glucogenic amino acids ________.

A) are converted to acetyl CoA

B) are converted to glucose

C) are catabolized to pyruvate or an intermediate in the citric acid cycle

D) can be converted to ketone bodies

31) Which quantities need to be considered in determining the ATP yield from the complete catabolism of a fatty acid?

A) The ATP used up in the synthesis of the acyl CoA

B) The ATP generated from coenzymes produced during b-oxidation

C) The ATP that results from the catabolism of each acetyl CoA

D) All of the quantities need to be considered.

32) What is ketosis?

A) The accumulation of ketone bodies

B) The synthesis of ketones from acetyl CoA

C) The reduction of ketone bodies

D) A medical condition that results from the consumption of acetone and/or other toxic ketones

33) What metabolic conditions induce ketosis?

A) starvation

B) vigorous dieting

C) uncontrolled diabetes

D) All of the choices are correct.

E) None of the choices are correct.

34) What metabolic intermediate is formed from the carbon skeleton of the amino acid asparagine?

A) α-ketoglutarate

B) Oxaloacetate

C) Citrate

D) Succinyl CoA

E) Fumarate

35) What metabolic intermediate is formed from the carbon skeleton of the amino acid valine?

A) α-ketoglutarate

B) Oxaloacetate

C) Citrate

D) Succinyl CoA

E) Fumarate

36) Which amino acid is classified as glucogenic?

A) Leucine

B) Proline

C) Lysine

D) None of the amino acids are classified as glucogenic.

37) Which amino acid is classified as ketogenic?

A) Histidine

B) Valine

C) Arginine

D) Leucine

38) Which process requires the coenzyme NADH?

A) Glucose → pyruvate

B) Pyruvate → acetaldehyde

C) Pyruvate → lactate

D) Pyruvate → acetyl CoA

E) More than one of the processes requires the coenzyme NADH.

39) Which factors increase the rate of gluconeogenesis?

A) High glycogen reserves

B) Low carbohydrate diet

C) High carbohydrate diet

D) Low oxygen concentration

40) How is the amino group of an amino acid lost as a result of transamination and oxidative deamination?

A) NH2–

B) NH3

C) NH4+

D) CH3NH2

41) The reduction of acetaldehyde, shown below, is the last step in the fermentation process. What is the product of the reduction of acetaldehyde?

A)

B)

C)

D)

42) The first step in gluconeogenesis is the oxidation of lactate. What product is formed when lactate is oxidized?

A)

B)

C)

D)

43) Under anaerobic conditions, the reaction of pyruvate with NADH and H+ should form which of the following products?

A)

B)

C)

D)

44) Step [9] in glycolysis, shown below, involves the dehydration of 2-phosphoglycerate. What is the structure of the dehydration product?

A)

B)

C)

D)

45) Step [7] of glycolysis is shown below. Which statement concerning this step is true?

A) The hydrolysis of ATP provides the necessary energy for the removal of a phosphate group from 1,3-bisphosphoglycerate.

B) The formation of 3-phosphoglycerate provides the necessary energy for the phosphorylation of ADP.

C) The energy required in the hydrolysis of 1,3-bisphosphoglycerate is stored in ADP.

D) The hydrolysis of 1,3-bisphosphoglycerate is an unfavorable reaction.

46) Which steps in glycolysis form ATP?

A) Steps 1 and 2

B) Steps 3 and 6

C) Steps 7 and 10

D) Steps 1 and 3

E) Steps 4 and 5

47) Which steps in glycolysis use ATP?

A) Steps 1 and 2

B) Steps 3 and 6

C) Steps 7 and 10

D) Steps 1 and 3

E) Steps 4 and 5

48) Glucosamine, shown below, is a competitive inhibitor of the enzyme hexokinase, which catalyzes the phosphorylation of glucose in the first step of glycolysis (Eqn. 1 below). Which statement best describes the inhibition by glucosamine?  

A) Glucosamine reacts with glucose, preventing glucose from binding to the active site of hexokinase.

B) Glucosamine binds to the active site of hexokinase, preventing glucose from binding.

C) Glucosamine stabilizes the active site of hexokinase, preventing glucose 6-phosphate from being released.

D) Glucosamine binds to the surface of hexokinase, causing a change in shape of the enzyme and the active site, preventing glucose from binding.

49) On the fatty acid structure below, identify which carbons are alpha (α) and beta (β), two important positions in the β-oxidation process.

A) C1 is alpha and C2 is beta

B) C3 is alpha and C2 is beta

C) C6 is alpha and C5 is beta

D) C5 is alpha and C4 is beta

E) C4 is alpha and C5 is beta

50) In glycolysis, two three-carbon molecules of pyruvate (CH3COCO2–) are formed from each glucose molecule.

51) Individuals with galactosemia lack one of the enzymes necessary for converting galactose to glucose 6-phosphate.

52) The phosphorylation of mannose to form mannose 6-phosphate requires energy from ATP.

53) Many cancerous tumors depend largely on glycolysis to supply their energy needs.

54) Oxygen is needed to oxidize NADH to NAD+.

55) Fermentation is the aerobic conversion of glucose to ethanol and CO2.

56) Gluconeogenesis is an anabolic process that synthesizes glucose from pyruvate.

57) Conceptually, gluconeogenesis is the reverse of glycolysis; that is, two molecules of pyruvate are converted to glucose by a stepwise pathway that passes through all of the same intermediates encountered in glycolysis.

58) Six of the steps of gluconeogenesis use the same enzymes as used in glycolysis.

59) Gluconeogenesis is not a commonly used metabolic pathway when carbohydrate intake is high.

60) The glycerol formed from triacylglycerol hydrolysis is converted in two steps to dihydroxyacetone phosphate.

61) Catabolism of a fatty acid produces more than twice the energy per gram as glucose (in terms of moles of ATP generated).

62) Ketogenesis is the synthesis of ketone bodies from acetyl CoA.

63) Ketone bodies are produced in the kidneys, and since they are small molecules that can hydrogen bond with water, they are readily soluble in blood and urine.

64) An abnormally high concentration of ketone bodies can lead to ketoacidosis—that is, an increase in the blood pH caused by the increased level of β-hydroxybutyrate and acetoacetate.

65) When acetyl CoA levels exceed the capacity of the citric acid cycle, acetyl CoA is converted to ketone bodies.

66) The breakdown of amino acids forms NH4+, which enters the urea cycle to form urea, and a carbon skeleton that is metabolized to either pyruvate, acetyl CoA, or an intermediate in the citric acid cycle.

67) Transamination removes the amino group from an amino acid, leaving a carbon skeleton that contains only carbon, hydrogen, and oxygen atoms.

68) In oxidative deamination, glutamate is re-converted to α-ketoglutarate, which can undergo transamination with another molecule of an amino acid and the cycle repeats.

69) The overall result of transamination and oxidative deamination is to remove an amino group from an amino acid and form an ammonium ion, NH4+.

70) The products that result when alanine is subjected to transamination followed by oxidative deamination are properly indicated below.

71) A glucogenic amino acid may also be a ketogenic amino acid.

72) When oxygen is plentiful, pyruvate is converted to acetyl CoA, which can enter the citric acid cycle.

73) Glycolysis occurs when the body has depleted its supplies of glucose and stored glycogen, and occurs during sustained physical exercise and fasting.

74) The rate of glycolysis decreases when the body's ATP concentration is high.

75) In fermentation, the six carbon atoms of glucose are converted to three molecules of ethanol.

76) Step [1] of the β-oxidation of a fatty acid is considered an oxidation reaction even though the product has no additional C–O bonds.

77) Low carbohydrate diets such as the Atkins diet induce the catabolism of stored fat for energy production to assist in weight loss.

78) The urea cycle is a multistep pathway that converts ammonium ions to urea, (NH2)2C=O, in the kidneys.

79) Gluconeogenesis is simply the reverse of glycolysis.

80) The major products of glycolysis are glucose and ATP.

81) 3-Phosphoglycerate and 2-phosphoglycerate, two intermediates in glycolysis, are related as stereoisomers.

82) Dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, two intermediates in glycolysis, are related as constitutional isomers.

83) Cortisol is an anti-inflammatory agent that also regulates carbohydrate metabolism. Cortisol contains a primary alcohol, a secondary alcohol, and a quaternary alcohol.

84) A kinase enzyme catalyzes the transfer of a phosphate group from one substrate to another.

85) A carboxylase enzyme catalyzes the removal of carbon dioxide from a substrate.

86) Glycolysis is a cyclic, 10-step pathway.

87) Glycolysis is an anaerobic pathway.

88) Glycolysis begins with the phosphorylation of glucose to form glucose 6-phosphate.

89) The first three steps of glycolysis add three phosphate groups to glucose.

90) ________ and ________ are obtained by the hydrolysis of the disaccharide sucrose, which is found in sugar beets and sugarcane.

91) Pyruvate is converted to ________ under anaerobic conditions.

92) The complete catabolism of glucose forms ________ CO2 molecules and ________ ATP molecules.

93) When energy demands are low, glucose is stored as the polymer ________ in the liver and muscles.

94) ________ is the main source of energy for cells and the only source of energy used by the brain.

95) ________ is the synthesis of glucose from noncarbohydrate sources—lactate, amino acids, or glycerol.

96) Fatty acid oxidation begins with the conversion of a fatty acid into a thioester with coenzyme A.

97) Under some circumstances, when glucose is unavailable or cannot pass into a cell for use as fuel, ketone bodies accumulate, a condition called ________.

98) Transamination is the transfer of an amino group from a(n) _____to a(n) ________, usually α-ketoglutarate.

99) The hydrolysis of ATP to ADP releases 7.3 kcal/mol of energy. If the coupled reaction below releases 3.4 kcal/mol of energy, then the amount of energy required for the phosphorylation of fructose 6-phosphate is ________ kcal/mol.