Deck 28: Specific Catabolic Pathways: Carbohydrate, Lipid, and Protein Metabolism

Question 1

Consider the following reaction sequence.
Which of the following is true of pathways by which energy is extracted from carbohydrates and glycerol?

A) They are both glycolysis pathways, but are different from one another.
B) They are the same as one another.
C) The pathway for carbohydrates does not involve glycolysis, but that for glycerol does.
D) The pathway for glycerol does not involve glycolysis, but that for carbohydrates does.

Answer 1

B

Question 2

Which of the following describes the relationship between glucose 6-phosphate and fructose 6-phosphate?

A) They are anomers.
B) They are enantiomers.
C) They are isomers.
D) There is no special relationship between them.

Answer 2

C

Question 3

Consider the following reaction sequence.
Why must carbohydrates, fats and proteins be broken down into small molecules?

A) so they can be absorbed through the walls of the stomach
B) so they can be absorbed through the walls of the intestines
C) so they can be properly excreted
D) so we can enjoy their tastes and aromas

Answer 3

B

Question 4

How many molecules of ATP are involved in the conversion of glucose to glucose 6-phosphate?

A) 0
B) 1
C) 2
D) 3

Question 5

How can the carbon skeletons of amino acids enter the common catabolic pathway?

A) as part of amino acids
B) as part of complete proteins
C) as acetyl coenzyme A
D) as any of these

Question 6

How can the carbon skeletons of amino acids enter the common catabolic pathway?

A) as part of amino acids
B) as part of complete proteins
C) as α-ketoacids
D) as any of these

Question 7

Consider the following reaction sequence.
Which of the following products result from the action of lipases on lipids?

A) fatty acids
B) glycerol
C) monoglycerides
D) all of these

Question 8

Which of the following describes the relationship between dihydroxyacetone phosphate and glyceraldehyde 3-phosphate?

A) They are anomers.
B) They are enantiomers.
C) They are isomers.
D) There is no special relationship between them.

Question 9

Consider the following reaction sequence.
Which of the following is(are) involved in the breaking down of di- and polysaccharides to monosaccharides?

A) enzymes
B) stomach acid
C) both a and b
D) neither a nor b

Question 10

The amino acid pool consists of which of the following?

A) the amino acids found in our diets
B) the free amino acids found inside the cells
C) the free amino acids found outside the cells
D) both b and c

Question 11

Which of the following enzymes is found in the stomach?

A) carboxypeptidase
B) chymotrypsin
C) pepsin
D) trypsin

Question 12

Phosphofructokinase is involved in the conversion of fructose 6-phosphate to which of the following?

A) fructose 1-phosphate
B) fructose 1,6-bisphosphate
C) glucose 1,6-bisphosphate
D) none of these

Question 13

Which of the following enzymes is found in the stomach?

A) carboxypeptidase
B) chymotrypsin
C) trypsin
D) none of them

Question 14

Which of the following is true of the amino acids in the amino acid pool?

A) They are never used as a fuel for energy.
B) They are sometimes used as a fuel for energy.
C) They are often used as a fuel for energy.
D) They are the major fuel used for energy.

Question 15

Which of the following is the product of the first step of glycolysis?

A) fructose
B) glucose
C) glucose 1-phosphate
D) glucose 6-phosphate

Question 16

Which of the following are needed to convert fructose 6-phosphate to fructose 1,6-bisphosphate?

A) only phosphofructokinase
B) only phosphofructokinase and Mg²⁺
C) phosphofructokinase, ADP, and Mg²⁺
D) phosphofructokinase, ATP, and Mg²⁺

Question 17

Consider the following reaction sequence.
Which of the following are not formed as a result the action of lipases on lipids?

A) amino acids
B) fatty acids
C) monoglycerides
D) None, all are formed from lipids.

Question 18

Which of the following is the pathway used by cells to obtain energy from fatty acids?

A) α-oxidation
B) α-reduction
C) β-oxidation
D) β-reduction

Question 19

Which of the following is not involved in the hydrolysis of proteins?

A) HCl
B) NaOH
C) intestinal enzymes
D) stomach enzymes

Question 20

The first three steps of glycolysis are collectively known as which of the following?

A) activation
B) initiation
C) initialization
D) precursors

Question 21

Which of the following gases is produced during the conversion of pyruvate of acetyl coenzyme A?

A) CO
B) CO₂
C) O₂
D) none of these

Question 22

The conversion of ribose to deoxyribose is an example of which of the following?

A) dehydration
B) oxidation
C) reduction
D) tautomerization

Question 23

Which of the following is the cause of muscle cramps associated with strenuous exercise?

A) acetate
B) citrate
C) lactate
D) pyruvate

Question 24

NADPH is needed for the synthesis of which of the following?

A) amino acids
B) cholesterol
C) unsaturated fatty acids
D) all of these

Question 25

The enzyme phosphoglycerate mutase promotes which of the following?

A) the hydrolysis of 3-phosphoglycerate
B) the isomerization of 3-phosphoglycerate
C) the oxidation of 3-phosphoglycerate
D) the reduction of 3-phosphoglycerate

Question 26

Which of the following chemicals causes much of the damage associated with fetal alcohol syndrome?

A) acetaldehyde
B) acetic acid
C) acetone
D) ethanol

Question 27

The conversion of pyruvate of acetyl coenzyme A is an example of which of the following?

A) carbonation
B) decarbonylation
C) oxidative decarboxylation
D) reductive decarboxylation

Question 28

The conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate produces which of the following?

A) AMP
B) ADP
C) ATP
D) none of these

Question 29

Which of the following is true of pyruvate kinase?

A) It is activated by AMP.
B) It plays a key regulatory role in glycolysis.
C) both a and b
D) neither a nor b

Question 30

Which of the following is true of those steps of glycolysis which yield pyruvate as the end product?

A) They all occur in the cytoplasm.
B) They all occur in the mitochondria.
C) They occur primarily in the cytoplasm.
D) They occur primarily in the mitochondria.

Question 31

The conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate is an example of which of the following reactions?

A) hydrolysis
B) isomerization
C) oxidation
D) reduction

Question 32

Which of the following is true of anaerobic reactions?

A) They are all redox reactions.
B) They are never redox reactions.
C) They occur in the presence of oxygen.
D) They occur in the absence of oxygen.

Question 33

In how many steps of the glycolysis pathway are Mg²⁺ ions needed?

A) 3
B) 4
C) 5
D) 6

Question 34

In the conversion of pyruvate to acetyl coenzyme A which species is the oxidizing agent?

A) ATP
B) NAD⁺
C) NADH
D) pyruvate

Question 35

The conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate requires which of the following?

A) ADP
B) ATP
C) NADH
D) NAD⁺

Question 36

The production of 3-phosphoglycerate from 1,3-bisphosphoglycerate is an example of which of the following?

A) addition
B) dephosphorylation
C) phosphorylation
D) oxidation

Question 37

In NADPH and NADP⁺ where does diphosphate bind to the two sugar units?

A) at carbon 1 on each of the two sugar units
B) at carbon 3 on one sugar unit and at carbon 5 on the other
C) at carbon 3 on each of the two sugar units
D) at carbon 5 on each of the two sugar units

Question 38

Which of the following is the main agent used to keep hemoglobin in its reduced form?

A) ATP
B) FAD
C) glutathione
D) NADP⁺

Question 39

Which enzyme is involved in the conversion of phosphoenolpyruvate to pyruvate?

A) enolase
B) ketolase
C) pyruvate kinase
D) pyruvate oxidase

Question 40

Which of the following is true of pyruvate kinase?

A) It is activated by ATP.
B) It plays a key regulatory role in glycolysis.
C) both a and b
D) neither a nor b

Question 41

How many ATP molecules are produced as a result of the complete metabolism of one molecule of glucose in the heart or liver?

A) 12
B) 24
C) 36
D) 38

Question 42

How many high-energy phosphate bonds are cleaved during activation of fatty acid β-oxidation?

A) 0
B) 1
C) 2
D) 3

Question 43

When a molecule of glycerol is metabolized how many ATP molecules are produced?

A) 3
B) 6
C) 18
D) 20

Question 44

Which of the following cannot be converted to a form which can enter the glycolysis pathway?

A) fructose
B) galactose
C) glycogen
D) None of them, they can all be converted.

Question 45

Addition across the double bond of a fatty acid results in which of the following?

A) putting a hydroxyl group on the α-carbon
B) putting a hydroxyl group on the β-carbon
C) putting hydroxyl groups on both the α- and β-carbons
D) putting a hydroxyl group on either the α- or β-carbon, depending on the identity of the original fatty acid

Question 46

When one molecule of glucose undergoes glycolysis, two molecules of pyruvate are produced; the pyruvates then undergoes oxidative decarboxylation to yield two acetyl CoA. How many net molecules of ATP are produced by the oxidative decarboxylation of two molecules of pyruvate to yield two acetyl CoA?

A) 2
B) 4
C) 6
D) 12

Question 47

For oxidative phosphorylation to occur which of the following is true of the NADH and H⁺ produced during glycolysis?

A) Since it is produced in the cytoplasm it can be used directly.
B) Since it is produced in the mitochondria it can be used directly.
C) Since it is produced in the cytoplasm it cannot be used directly because oxidative phosphorylation occurs in the mitochondria.
D) Since it is produced in the mitochondria it cannot be used directly because oxidative phosphorylation occurs in the cytoplasm.

Question 48

In a fatty acid which carbon atom is the β-carbon?

A) carbon-2
B) carbon-3
C) the second carbon from the hydrophobic end
D) none of these

Question 49

Which of the following is the initial product formed during glycerol catabolism?

A) glycerol 1-phosphate
B) glycerol 2-phosphate
C) glycerol 1,2-bisphosphate
D) glycerol 1,3-bisphosphate

Question 50

In the transport mechanism which operates in the heart and liver, how many ATP molecules are produced for each NADH + H⁺?

A) 1
B) 2
C) 3
D) 4

Question 51

Which of the following is the oxidizing agent in the first oxidation step of β-oxidation of fatty acids?

A) FAD
B) FADH₂
C) NAD⁺
D) NADH + H⁺

Question 52

When one molecule of glucose undergoes glycolysis, two molecules of glyceraldehyde 3-phosphate are produced; these are then phosphorylated to yield two 1,3-bisphosphoglycerates. How many molecules of ATP are produced by the phosphorylation of two molecules of glyceraldehyde 3-phosphate to yield two 1,3-bisphosphoglycerates?

A) 2
B) 4
C) 6
D) 12

Question 53

Which of the following is(are) consumed in the process of converting glycerol to dihydroxyacetone phosphate?

A) ATP
B) NAD⁺
C) both a and b
D) neither a nor b

Question 54

When one molecule of glucose undergoes glycolysis, two molecules of 1,3-bisphosphoglycerate are produced; these are then dephosphorylated to yield two pyruvates. How many molecules of ATP are produced by the dephosphorylation of two molecules of 1,3-bisphosphoglycerate to yield two pyruvates?

A) 2
B) 4
C) 6
D) 12

Question 55

What is the name for the process in which glycogen is converted to glucose?

A) digestion
B) glucogenesis
C) glycogenolysis
D) none of these

Question 56

In what form(s) is the fatty acid transported from the cytosol to the mitochondria?

A) as a free fatty acid
B) as acetyl CoA
C) as acyl CoA
D) all of these

Question 57

How many ATP molecules are produced as a result of the complete metabolism of one molecule of glucose in skeletal muscles?

A) 4
B) 6
C) 24
D) 36

Question 58

In glycerol 3-phosphate transport, found in muscle and nerve cells, how many ATP molecules are produced for each NADH + H⁺?

A) 1
B) 2
C) 3
D) 4

Question 59

The action of acyl-CoA dehydrogenase and FAD on the fatty acid results in which of the following?

A) elimination of a C₂ fragment
B) formation of a cis-double bond between the α- and β-carbon atoms
C) formation of a trans-double bond between the α- and β-carbon atoms
D) none of the above

Question 60

Which of the following is(are) consumed in the process of converting glycerol to dihydroxyacetone phosphate?

A) ADP
B) NADH⁺
C) both a and b
D) neither a nor b

Question 61

Oxidation of a hydroxy fatty acid does which of the following?

A) converts an α-hydroxy to an α-ketone
B) converts a β-hydroxy to an β-ketone
C) both a nor b
D) neither a nor b

Question 62

The NADH + H⁺ produced during the catabolism of amino acids ultimately results in the production of how many molecules of ATP?

A) 1
B) 2
C) 3
D) 4

Question 63

The accumulation of ketone bodies in the blood results in which of the following?

A) a decrease in [Na+] in the interstitial fluids
B) an increase in the pH of the blood
C) both a and b
D) neither a nor b

Question 64

The formation of β-hydroxybutyrate from acetoacetate is an example of which of the following type of reaction?

A) decarboxylation
B) hydrolysis
C) reduction
D) oxidation

Question 65

Which of the following enzymes is associated with the removal of a C₂ fragment from the fatty acid?

A) acyl CoA dehydrogenase
B) carnitine
C) hydroxyacyldehydrogenase
D) thiolase

Question 66

Which of the following is true if a diet provides an adequate supply of sugars?

A) Most of the energy required by the body is obtained from fatty acids.
B) The available supply of sugar has no effect on the β-oxidation pathway.
C) The β-oxidation pathway is inhibited.
D) The β-oxidation pathway is mobilized.

Question 67

Which of the following is the oxidizing agent in the second oxidation step of the β-oxidation of fatty acids?

A) FAD
B) FADH₂
C) NAD⁺
D) NADH + H⁺

Question 68

What fraction of the energy produced by the complete metabolism of stearic acid is associated with β-oxidation of the acid?

A) approximately 25%
B) approximately 50%
C) approximately 75%
D) 100%

Question 69

α-Ketoglutarate is involved in both transamination and oxidative deamination. Which of the following describes its involvement in these two processes?

A) It is a product of both transamination and oxidative deamination.
B) It is a reactant in both transamination and oxidative deamination.
C) It is a reactant in oxidative deamination and a product in transamination.
D) It is a reactant in transamination and a product in oxidative deamination.

Question 70

Complete metabolism of which of the following fatty acids will yield the most ATP molecules per carbon atom?

A) CH₃(CH₂)₁₂COOH
B) CH₃(CH₂)₁₄COOH
C) CH₃(CH₂)₁₆COOH
D) None, they all yield the same number of ATPs/C.

Question 71

Which of the following is true when comparing the β-oxidation of a naturally occurring unsaturated fatty acid to that of a saturated fatty acid?

A) It is identical to the β-oxidation of a saturated fatty acid.
B) It involves an extra step to convert a cis double bond to a trans double bond.
C) It involves an extra step to convert a trans double bond to a cis double bond.
D) It proceeds by a totally different pathway.

Question 72

Which of the following could be the reactants in an oxidative deamination?

A) α-ketoglutarate, NAD⁺ and H₂O
B) α-ketoglutarate, NADH and H⁺
C) glutamate, NAD⁺ and H₂O
D) glutamate, NADH and H⁺

Question 73

The formation of acetone from acetoacetate is an example of which of the following type of reaction?

A) decarboxylation
B) hydrolysis
C) reduction
D) oxidation

Question 74

How many molecules of ATP are produced during a single turn of the β-oxidation cycle?

A) 2
B) 3
C) 4
D) 5

Question 75

The accumulation of ketone bodies in the blood results in which of the following?

A) a decrease in the pH of the blood
B) no effect on the pH of the blood
C) an increase in the pH of the blood
D) an increase in [Na⁺] in the interstitial fluids

Question 76

The urea cycle does which of the following?

A) It generates molecules which can enter the common metabolic pathway.
B) It removes the NH₄⁺ which is produced by oxidative deamination.
C) both a and b
D) neither a nor b

Question 77

Carbamoyl phosphate is formed in which region(s) of the cell?

A) the cytoplasm
B) the mitochondria
C) both a and b
D) neither a nor b

Question 78

How does the body utilize amino acids which are not needed for the synthesis of proteins and other biological molecules?

A) It catabolizes them.
B) It stores them.
C) both a and b
D) neither a nor b

Question 79

Since naturally occurring fatty acids contain an even number of carbon atoms, the number of carbon atoms in such compounds can be expressed as 2n. How many turns of the β-oxidation cycle occur during the breakdown of a fatty acid which contains 2n carbon atoms?

A) n − 2
B) n − 1
C) n
D) n + 1

Question 80

Which of the following is a reactant in transamination?

A) α-ketoglutarate
B) β-ketogluarate
C) glutamate
D) none of these