Deck 25: Lipid Metabolism

Question 1

Lipoproteins that transport triacylglycerols from intestinal cells to the bloodstream are called

A) chylomicrons
B) fatty acid micelles
C) adipocytes
D) chymes

Answer 1

chylomicrons

Question 2

Before a fatty acid can undergo $\beta$ -oxidation, it must be activated and then shuttled across the inner mitochondrial membrane. The activating agent and shuttle molecule are, respectively,

A) CoA and carnitine
B) CoA and citrate
C) acetyl CoA and carnitine
D) acetyl CoA and citrate

Answer 2

CoA and carnitine

Question 3

The notation ACP stands for

A) acyl carnitine pyruvate
B) acyl carrier protein
C) acetyl carnitine pyruvate
D) acetyl carrier protein

Answer 3

acyl carrier protein

Question 4

Which of the following statements concerning "fuel usage" in the human body is incorrect?

A) Skeletal muscle in a resting state uses glucose.
B) Cardiac muscle depends first on fatty acids and secondarily on ketone bodies.
C) Brain function is maintained primarily by glucose.
D) The liver uses fatty acids as the primary fuel.

Question 5

The two major products of triacylglycerol digestion in the small intestine are fatty acids and

A) glycerol
B) monoacylglycerols
C) diacylglycerols
D) acetyl CoA

Question 6

How many FADH₂ and NADH molecules are produced, respectively, after 6 "turns" of the $\beta$ -oxidation pathway?

A) 6, 6
B) 6, 12
C) 12, 6
D) 6, 18

Question 7

The carrier of the "two carbon units" used to biosynthesize a fatty acid is

A) acetyl CoA
B) acetyl ACP
C) malonyl CoA
D) malonyl ACP

Question 8

What is the net ATP production for the complete degradation of a C₂₀ fatty acid molecule to CO₂ and H₂O?

A) 134
B) 148
C) 162
D) 176

Question 9

The correct sequence for the four reactions of the $\beta$ -oxidation pathway in terms of "functional group acted upon" is

A) alkene, alkane, ketone, 2 $\degree$ alcohol
B) alkane, alkene, 2 $\degree$ alcohol, ketone
C) alkane, ketone, 2 $\degree$ alcohol, alkene
D) ketone, 2 $\degree$ alcohol, alkene, alkane

Question 10

The starting material for the process of ketogenesis is

A) acetyl CoA
B) oxaloacetate
C) pyruvate
D) citrate

Question 11

The major function for bile released during the digestion of triacylglycerols is to

A) facilitate the formation of chyme
B) act as an enzyme
C) act as an emulsifier
D) hydrolyze ester linkages within triacylglycerols

Question 12

How many "turns" in the $\beta$ -oxidation pathway are needed to "process" a C₂₀ fatty acid molecule?

A) 9
B) 10
C) 18
D) 20

Question 13

The correct sequence for the four reactions of the $\beta$ -oxidation pathway in terms of "type of reaction occurring" is

A) dehydrogenation, dehydrogenation, hydration, thiolysis
B) dehydrogenation, hydration, dehydrogenation, thiolysis
C) thiolysis, hydration, dehydration, dehydrogenation
D) thiolysis, dehydration, hydration, dehydration

Question 14

How many times do dietary triacylglycerols undergo hydrolysis before they become available for use by cells?

A) one
B) two
C) three
D) four

Question 15

Three of the following four compounds are classified as ketone bodies. The one that is not is

A) acetoacetate
B) ( $\beta$ -hydroxybutyrate)
C) acetobutyrate
D) acetone

Question 16

The first stage of glycerol metabolism involves a two-step process in which the glycerol is converted to

A) glycerol 3-phosphate
B) dihydroxyacetone phosphate
C) 3-phosphoglycerate
D) 2-phosphoglycerate

Question 17

Which of the following chemical changes is not possible within the human body?

A) pyruvate to acetyl CoA
B) acetyl CoA to pyruvate
C) fatty acid to CO₂ and H₂O via acetyl CoA, the CAC, and the ETC
D) glucose to fatty acid via acetyl CoA

Question 18

The reducing agent needed in the process of lipogenesis is

A) NADPH
B) NADH
C) FADH₂
D) ADP

Question 19

Which of the following is a correct ordering of cholesterol intermediates as they are encountered during the biosynthesis of cholesterol?

A) isopentenyl pyrophosphate, mevalonate, squalene
B) isopentenyl pyrophosphate, squalene, mevalonate
C) mevalonate, isopentenyl pyrophosphate, squalene
D) mevalonate, squalene, isopentenyl pyrophosphate

Question 20

Which of the following processes requires molecular O₂ as a reactant?

A) saturated fatty acid degradation to acetyl CoA
B) saturated fatty acid biosynthesis
C) unsaturated fatty acid degradation to acetyl CoA
D) unsaturated fatty acid biosynthesis

Question 21

One "turn" in the F $\beta$ -oxidation pathway produces

A) an acetyl CoA molecule
B) two molecules of ATP
C) an acyl CoA molecule that has been shortened by two carbon atoms
D) more than one correct response
E) no correct response

Question 22

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:

-Statements: (1) The number of acetyl CoA molecules produced in the $\beta$ -oxidation pathway is equal to half the number of carbon atoms in the fatty acid that is processed.
(2) A fatty acid micelle is a lipoprotein that transports TAGs from the intestinal walls to the bloodstream.
(3) Associated with the conversion of acetyl CoA to malonyl CoA, in lipogenesis, is the production of a carbon dioxide 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.

Question 23

Which of the following compounds is a ketone body?

A) acetoacetate
B) oxaloacetate
C) acetyl CoA
D) more than one correct response
E) no correct response

Question 24

Which of the following relationships involving "turns" in the $\beta$ -oxidation pathway are correct?

A) 8 turns; 9 acetyl CoA molecules
B) 7 turns; 8 NADH molecules
C) 6 turns; 7 FADH₂ molecules
D) more than one correct response
E) no correct response

Question 25

Which of the following pairings of information about intermediates in the biosynthesis of cholesterol is correct?

A) mevalonate; a C₅ molecule
B) squalene; a C₂₀ molecule
C) lanosterol; a C₃₀ molecule
D) more than one correct response
E) no correct response

Question 26

Which of the following compounds is an intermediate in the conversion of glycerol to dihydroxyacetone phosphate?

A) acetoacetate
B) acetone
C) 3-phosphoglycerate
D) more than one correct response
E) no correct response

Question 27

Which of the following pairings of terms is correct for reactions in the $\beta$ -oxidation pathway?

A) alkene functional group; dehydrogenation
B) ketone functional group; thiolysis
C) alkane functional group; hydration
D) more than one correct response
E) no correct response

Question 28

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:

-Statements: (1) The process by which ketone bodies are produced from acetyl CoA is called ketosis.
(2) The number of "turns" in the $\beta$ -oxidation pathway needed to process an 18-carbon saturated fatty acid is nine.
(3) Glycerol metabolism involves production of dihydroxyacetone phosphate, which then enters the glycolysis 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.

Question 29

Which of the following statements concerning lipogenesis is correct?

A) It occurs in the cytosol of a cell.
B) It involves a multienzyme complex rather than a series of individual enzymes.
C) It is dependent on the oxidizing agents FAD and NAD⁺.
D) More than one correct response.
E) No correct response.

Question 30

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:

-Statements: (1) The $\beta$ -oxidation pathway involves a repetitive series of four reactions.
(2) Triacylglycerol mobilization is a hydrolysis process that occurs in adipose tissue.
(3) ATP and ACP have similar functions within the human body.

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.

Question 31

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:
Statements: (1) Both TAG emulsification and TAG digestion occur in the small intestine.
(2) On an equal-mass basis, fatty acids produce more than twice as much ATP per gram as carbohydrates (glucose).
(3) The "opposite" processes of lipogenesis and fatty acid oxidation cannot occur at the same time.

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.

Question 32

Which of the following is a possible fate for the acetyl CoA produced from the degradation of a fatty acid?

A) conversion to pyruvate
B) ketone body formation
C) cholesterol biosynthesis
D) more than one correct response
E) no correct response

Question 33

The molecule carnitine is involved in

A) glycerol catabolism
B) fatty acid activation
C) a shuttle system for acyl CoA
D) more than one correct response
E) no correct response

Question 34

Which of the following statements concerning the chain elongation phase of fatty acid biosynthesis is correct?

A) Step 1 involves a condensation reaction.
B) Step 2 involves a hydration reaction.
C) Step 3 involves a dehydrogenation reaction.
D) More than one correct response.
E) No correct response.

Question 35

Which of the following generalizations about "fuel" use in the human body is incorrect?

A) Skeletal muscle in an active state uses fatty acids.
B) Skeletal muscle in a resting state uses glucose.
C) Heart muscle uses glucose as a preferred fuel.
D) More than one correct response.
E) No correct response.

Question 36

Which of the following is a lipoprotein?

A) chylomicrons
B) fatty acid micelles
C) adipocytes
D) more than one correct response
E) no correct response

Question 37

Which of the following statements concerning digestion of dietary triacylglycerols in adults is correct?

A) Triacylglycerol digestion begins in the mouth.
B) Triacylglycerol digestion occurs to a small extent (10%) in the stomach.
C) Triacylglycerol digestion occurs only in the small intestine.
D) More than one correct response.
E) No correct response.

Question 38

Which of the following is an intermediate in the process of lipogenesis?

A) isopentenyl pyrophosphate
B) malonyl ACP
C) oxaloacetate
D) more than one correct response
E) no correct response

Question 39

Which of the following enzymes are required for processing unsaturated fatty acids through the $\beta$ -oxidation pathway but not for processing saturated fatty acids through the pathway?

A) an epimerase to change a D-isomer to a L-isomer
B) an isomerase to change a cis (3, 4) bond to a trans (2, 3) bond
C) a transferase to change a $\beta$ -hydroxyacyl CoA to a á-hydroxyacyl CoA
D) more than one correct response
E) no correct response

Question 40

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:
Statements: (1) Initial triacylglycerol digestion usually produces monoacylglycerols rather than glycerol itself.
(2) Fatty acids are the preferred fuel for "running" the heart (cardiac muscle) and the brain.
(3) The ketone body acetoacetate is the "parent" compound for the other four ketone bodies.

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.

Question 41

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:

-Statements:
(1) The ketone body acetoacetate lowers blood pH because of the presence of a carboxyl (acid) group in its structure.
(2) Two products of the initial "turn" in the $\beta$ -oxidation pathway are acetyl CoA and a fatty acid that contains two more carbon atoms than the reactant fatty acid.
(3) Fatty acids produced through lipogenesis cannot contain more than 14 carbon atoms.

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.

Question 42

Use the following to answer the questions below:
For each of the substances, select from the response list the process with which it is associated. Responses may be used more than once or need not be used at all.


-Malonyl CoA

A) ketogenesis
B) lipogenesis
C) ( $\beta$ -oxidation pathway)
D) glycerol degradation

Question 43

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:
Statements: (1) When the amount of acetyl CoA is excessive compared with the amount of oxaloacetate available to react with it, ketone body formation occurs.
(2) The transport stage of fatty acid oxidation involves the shuttle molecule acyl carnitine.
(3) As a part of digestion of lipids, enzymes in bile help "solubilize" the lipids.

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.

Question 44

Use the following to answer the questions below:
Identify the step (1 through 4) in a "turn" in the $\beta$ -oxidation pathway at which each of the compounds would be encountered as a reactant using the response list. Responses may be used more than once or need not be used at all.


-How many acetyl CoA are produced?

A) 7
B) 8
C) 106
D) 108

Question 45

Use the following to answer the questions below:
For each of the substances, select from the response list the process with which it is associated. Responses may be used more than once or need not be used at all.


-Dihydroxyacetone phosphate

A) ketogenesis
B) lipogenesis
C) ( $\beta$ -oxidation pathway)
D) glycerol degradation

Question 46

Use the following to answer the questions below:
On the left are characteristics of various reactions that occur in the chain elongation phase of fatty acid biosynthesis. Identify the step (1 through 4) of the chain elongation process to which each characterization applies using the response list on the right. Responses on the right may be used more than once or need not be used at all.

Malonyl ACP is a reactant.

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

Question 47

Use the following to answer the questions below:
For each of the substances, select from the response list the process with which it is associated. Responses may be used more than once or need not be used at all.


-Carnitine

A) ketogenesis
B) lipogenesis
C) ( $\beta$ -oxidation pathway)
D) glycerol degradation

Question 48

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:

-Statements: (1) The functional group change sequence "alkane-alkene-primary alcohol-ketone" occurs during each "turn" of the $\beta$ -oxidation pathway.
(2) Squalene and lanosterol, intermediates in cholesterol biosynthesis, contain more carbon atoms than does cholesterol.
(3) The acetyl CoA needed for lipogenesis is shuttled from mitochondria to the cytosol via a citrate shuttle.

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.

Question 49

Use the following to answer the questions below:
For each of the substances, select from the response list the process with which it is associated. Responses may be used more than once or need not be used at all.


-Glycerol 3-phosphate

A) ketogenesis
B) lipogenesis
C) ( $\beta$ -oxidation pathway)
D) glycerol degradation

Question 50

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:
Statements: (1) The human body, in the resting state, burns more fat than carbohydrate.
(2) The initial stages of exercise are fueled primarily by glucose.
(3) Statins lower plasma concentrations of LDL by inhibiting cholesterol synthesis in the liver.

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.

Question 51

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:
Statements: (1) The products of the first two stages of cholesterol biosynthesis are, respectively, mevalonate (C₆) and isopentenyl pyrophosphate (C₅).
(2) Over 90 percent of total dietary lipids are triacylglycerols.
(3) The activation stage of fatty acid oxidation involves both CoA and ATP.

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.

Question 52

Use the following to answer the questions below:
Identify the step (1 through 4) in a "turn" in the $\beta$ -oxidation pathway at which each of the compounds would be encountered as a reactant using the response list. Responses may be used more than once or need not be used at all.


-What is the net ATP production for complete degradation of the fatty acid to CO₂ and H₂O?

A) 7
B) 8
C) 106
D) 108

Question 53

Use the following to answer the questions below:
On the left are characteristics of various reactions that occur in the chain elongation phase of fatty acid biosynthesis. Identify the step (1 through 4) of the chain elongation process to which each characterization applies using the response list on the right. Responses on the right may be used more than once or need not be used at all.

CO₂ is a product.

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

Question 54

Use the following to answer the questions below:
On the left are characteristics of various reactions that occur in the chain elongation phase of fatty acid biosynthesis. Identify the step (1 through 4) of the chain elongation process to which each characterization applies using the response list on the right. Responses on the right may be used more than once or need not be used at all.

ACP is a product.

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

Question 55

Use the following to answer the questions below:
Identify the step (1 through 4) in a "turn" in the $\beta$ -oxidation pathway at which each of the compounds would be encountered as a reactant using the response list. Responses may be used more than once or need not be used at all.


-How many FADH₂ are produced?

A) 7
B) 8
C) 106
D) 108

Question 56

Use the following to answer the questions below:
For each of the substances, select from the response list the process with which it is associated. Responses may be used more than once or need not be used at all.


-Acetoacetyl ACP

A) ketogenesis
B) lipogenesis
C) ( $\beta$ -oxidation pathway)
D) glycerol degradation

Question 57

Use the following to answer the questions below:
Identify the step (1 through 4) in a "turn" in the $\beta$ -oxidation pathway at which each of the compounds would be encountered as a reactant using the response list. Responses may be used more than once or need not be used at all.


-How many NADH are produced?

A) 7
B) 8
C) 106
D) 108

Question 58

Use the following to answer the questions below:
On the left are characteristics of various reactions that occur in the chain elongation phase of fatty acid biosynthesis. Identify the step (1 through 4) of the chain elongation process to which each characterization applies using the response list on the right. Responses on the right may be used more than once or need not be used at all.

A dehydration reaction occurs.

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

Question 59

Use the following to answer the questions below:
On the left are characteristics of various reactions that occur in the chain elongation phase of fatty acid biosynthesis. Identify the step (1 through 4) of the chain elongation process to which each characterization applies using the response list on the right. Responses on the right may be used more than once or need not be used at all.

A carbon-carbon double bond is converted to a carbon-carbon single bond.

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

Question 60

Use the following to answer the questions below:
Identify the step (1 through 4) in a "turn" in the $\beta$ -oxidation pathway at which each of the compounds would be encountered as a reactant using the response list. Responses may be used more than once or need not be used at all.


-How many "turns" in the $\beta$ -oxidation pathway are needed?

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

Question 61

Use the following to answer the questions below:
For each of the substances, which are associated with the biosynthesis of cholesterol, select the number of carbon atoms present in the substance using the response list. Responses may be used more than once or need not be used at all.

Cholesterol

A) C₅ molecule
B) C₆ molecule
C) C₂₇ molecule
D) C₃₀ molecule

Question 62

Use the following to answer the questions below:
For each of the substances, which are associated with the biosynthesis of cholesterol, select the number of carbon atoms present in the substance using the response list. Responses may be used more than once or need not be used at all.

Squalene

A) C₅ molecule
B) C₆ molecule
C) C₂₇ molecule
D) C₃₀ molecule

Question 63

Use the following to answer the questions below:
For each of the substances, which are associated with the biosynthesis of cholesterol, select the number of carbon atoms present in the substance using the response list. Responses may be used more than once or need not be used at all.

Mevalonate

A) C₅ molecule
B) C₆ molecule
C) C₂₇ molecule
D) C₃₀ molecule

Question 64

Use the following to answer the questions below:
For each of the substances, which are associated with the biosynthesis of cholesterol, select the number of carbon atoms present in the substance using the response list. Responses may be used more than once or need not be used at all.

Isopentenyl pyrophosphate

A) C₅ molecule
B) C₆ molecule
C) C₂₇ molecule
D) C₃₀ molecule

Question 65

Use the following to answer the questions below:
For each of the substances, which are associated with the biosynthesis of cholesterol, select the number of carbon atoms present in the substance using the response list. Responses may be used more than once or need not be used at all.

Lanosterol

A) C₅ molecule
B) C₆ molecule
C) C₂₇ molecule
D) C₃₀ molecule