Deck 24: Carbohydrate,lipid,and Protein Metabolism

Question 1

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.

Answer 1

Pyruvate and NAD⁺ are transported to the muscle.

Question 2

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

Answer 2

10

Question 3

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

A)Galactase
B)Glucose 1-phosphate
C)Galactose
D)Galactose 6-phosphate

Answer 3

Galactose

Question 4

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

Question 5

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.

Question 6

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

Question 7

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

A)Glucose
B)ATP
C)NADH
D)Pyruvate

Question 8

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

Question 9

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

Question 10

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.

Question 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

Question 12

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.

Question 13

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

Question 14

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

Question 15

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

Question 16

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

Question 17

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

A)Glucose
B)Galactose
C)Pyruvate
D)Lactate
E)Acetyl CoA

Question 18

Which enzyme is capable of catalyzing the reaction shown?

A)Propanol kinase
B)Propanol isomerase
C)Propanol dehydrogenase
D)Propanol carboxylase

Question 19

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.

Question 20

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

Question 21

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

Question 22

Which amino acid is classified as glucogenic?

A)Leucine
B)Proline
C)Lysine
D)None of the amino acids are classified as glucogenic.

Question 23

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

Question 24

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.

Question 25

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.

Question 26

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

Question 27

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.

Question 28

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

Question 29

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.

Question 30

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

Question 31

What are the products formed in the transamination reaction shown?

A)
B)
C)
D)

Question 32

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.

Question 33

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

Question 34

Which amino acid is classified as ketogenic?

A)Histidine
B)Valine
C)Arginine
D)Leucine

Question 35

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.

Question 36

Which factors increase the rate of gluconeogenesis?

A)High glycogen reserves
B)Low carbohydrate diet
C)High carbohydrate diet
D)Low oxygen concentration

Question 37

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

Question 38

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

Question 39

Which compound is not a ketone body?

A)Acetoacetate
B)Acetone
C)β-hydroxybutyrate
D)Acetyl CoA

Question 40

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

Question 41

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

A)
B)
C)
D)

Question 42

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

Question 43

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.

Question 44

Oxygen is needed to oxidize NADH to NAD⁺.

Question 45

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

Question 46

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

Question 47

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

A)
B)
C)
D)

Question 48

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

Question 49

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

Question 50

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

Question 51

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.

Question 52

Gluconeogenesis is an anabolic process that synthesizes glucose from pyruvate.

Question 53

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

A)
B)
C)
D)

Question 54

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

Question 55

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

Question 56

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

Question 57

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

Question 58

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.

Question 59

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)

Question 60

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

Question 61

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.

Question 62

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

Question 63

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

Question 64

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.

Question 65

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

Question 66

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.

Question 67

Ketogenesis is the synthesis of ketone bodies from acetyl CoA.

Question 68

Gluconeogenesis is simply the reverse of glycolysis.

Question 69

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

Question 70

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

Question 71

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.

Question 72

The major products of glycolysis are glucose and ATP.

Question 73

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

Question 74

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.

Question 75

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

Question 76

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

Question 77

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

Question 78

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

Question 79

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

Question 80

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