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Biochemistry Test 3 > Topic 6 Practice Problems > Flashcards

Topic 6 Practice Problems Flashcards

1
Q

The standard free energy change for the hydrolysis of ATP to ADP and inorganic phosphate (Pi) is about -30 kJ/mol but in the red blood cell the actual free energy change for this reaction is about -52 kJ/mol. This means that:
A. The concentration of ATP is more than 1 M.
B. The product of the concentrations of ADP and Pi is greater than the concentration of ATP.
C. The concentration of ATP is greater than the product of the concentrations of ADP and Pi.
D. The concentration of inorganic phosphate is much lower that that of ADP.

A

C. The concentration of ATP is greater than the product of the concentrations of ADP and Pi.

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2
Q 
In the equation, which is the oxidizing agent?
A.  NAD+
B.  Acetaldehyde
C.  Ethanol
D.  NADH
E.   H+
A

A. NAD+

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3
Q 
Referring to the equation, which molecule loses electrons?
A.  NADH
B.  NAD+
C.  Ethanol
D.  H+
E.  Acetaldehyde
A

C. Ethanol

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4
Q

Which of the following is FALSE for catabolic pathways?

A. They generate ATP.
B. They extract usable chemical energy from fuel molecules.
C. They are oxidative.
D. They generate oxidized enzyme cofactors.

A

D. They generate oxidized enzyme cofactors.

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5
Q 
Which of the following is always involved in biological oxidation-reduction reactions?
A.  Formation of water.
B.  Transfer of electron(s).
C.  Inner mitochondrial membrane.
D.  Oxygen.
A

B. Transfer of electron(s).

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6
Q

Which of the following statements concerning metabolic pathways is TRUE?
A. All reactions in a metabolic pathway are tightly regulated.
B. Metabolic pathways may have either a net positive or net negative free energy.
C. Opposing metabolic pathways do NOT occur.
D. Many of the reactions in a metabolic pathway are thermodynamically reversible.

A

D. Many of the reactions in a metabolic pathway are thermodynamically reversible.

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7
Q

Which of the following statements concerning ATP is TRUE?
A. The phosphoanhydride bonds in ATP are “high energy bonds” that are different from other covalent bonds.
B. The hydrolysis of phosphoanhydride bonds in ATP releases large amounts of free energy.
C. Phosphate groups within ATP experience more resonance stabilization than free phosphate groups.
D. The formation of phosphoanhydride bonds in ATP relieves electrostatic repulsion.

A

B. The hydrolysis of phosphoanhydride bonds in ATP releases large amounts of free energy.

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8
Q

Examine the following reactions:
Reaction 1. Glycerol 1-phosphate + H2O —-> Glycerol + Pi G = -9
Reaction 2. ATP + H2O ——–> ADP + Pi + H+ G = -30
What is the balanced equation and theG of the coupled reaction?
A. Glycerol + ATP —–> Glycerol 1-phosphate + ADP + H+ G = -21
B. Glycerol 1-phosphate + ADP + H+ ———> Glycerol + ATP G = -39
C. Glycerol 1-phosphate + ADP + H+ ——–> Glycerol + ATP G = -21
D. Glycerol + ATP ——> Glycerol 1-phosphate + ADP + H+ G = -39

A

A. Glycerol + ATP —–> Glycerol 1-phosphate + ADP + H+ G = -21

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9
Q

Which of the statements correctly describes the schematic pathway shown?
A->BCDEF
A. Four of the reactions shown are irreversible.
B. One of the reactions shown is endergonic.
C. It is likely that all of the enzymes catalyzing the reactions in this pathway are regulated.
D. A metabolic pathway with a starting metabolite of F and a product of A could exist in the same cell as the pathway shown above.
E. The concentrations of metabolites C, D and E likely change over time depending on the metabolic status of the cell.

A

D. A metabolic pathway with a starting metabolite of F and a product of A could exist in the same cell as the pathway shown above.

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10
Q

A hypothetical metabolic pathway is depicted below. A, B, C, D and E are the metabolic intermediates. E1 through E4 catalyze the 4 reactions. The free energy change for each reaction is shown below the arrow in kJ/mol. What MOST LIKELY happens if the concentration of metabolite C is increased?
AB->CDE
A. The reverse reaction C to B will be driven to equilibrium.
B. The increased concentration of C will feedback inhibit enzyme E1.
C. The flux through the pathway from C to E will increase.
D. The increased concentration of C will feed-forward activate enzyme E4.

A

C. The flux through the pathway from C to E will increase.

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11
Q

Why is acetyl-CoA considered a high energy molecule?
A. Large amounts of ATP are released upon oxidation.
B. Large amounts of ATP are released upon deacetylation.
C. It contains an ester bond.
D. It contains a thioester bond.

A

D. It contains a thioester bond.

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12
Q

Which of the following bonds or functional groups is NOT found in ADP?
A. A phosphoester bond
B. A purine base
C. Neither a phosphoester bond nor deoxyribose
D. Deoxyribose
E. A phosphoanhydride bond

A

D. Deoxyribose

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13
Q

∆Go’ for the hydrolysis of ATP is – 31 kJ/mol. How will the standard free energy change be altered if the activity of the enzyme catalyzing ATP hydrolysis is reduced?
A. It will decrease.
B. It will stay the same.
C. It will increase.

A

B. It will stay the same.

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14
Q

Energy is generated during _____, the breakdown of larger molecules into smaller while energy is consumed during _____, the building of larger molecules from smaller ones.
A. reduction reactions; oxidation reactions
B. autotrophic reactions; heterotrophic reactions
C. catabolic reactions; anabolic reactions
D. hydrolysis reactions; condensation reactions
E. none of the above

A

C. catabolic reactions; anabolic reactions

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15
Q 
The bulk of triacylglycerols in the human body are stored in \_\_\_\_\_.
A.  liver cells 
B.  nerve cells 
C.  adipocytes 
D.  muscle cells 
E.  lipoproteins
A

C. adipocytes

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16
Q 
Which of the following is mobilized for energy use by a phosphorolysis reaction, not a hydrolysis?
A. polynucleotides 
B. protein 
C.  cholesterol esters 
D.  glycogen 
E.  triacylglycerols
A

D. glycogen

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17
Q 
Which of the following molecules is involved with the oxidation of glucose, synthesis of fatty acids and oxidation of fatty acids?
A.  pyruvate 
B.  acetyl-CoA 
C.  oxaloacetate 
D.  alanine 
E.  glyceraldehyde-3-phosphate
A

B. acetyl-CoA

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18
Q 
The conversion of a carbohydrate into CO2 is a(n) \_\_\_\_\_ process; the conversion of CO2 into a carbohydrate is a(n) \_\_\_\_\_ process.
A.  oxidative; exergonic 
B.  endergonic; reductive 
C.  exergonic; endergonic
D.  reductive; oxidative 
E.  endergonic; exergonic
A

C. exergonic; endergonic

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19
Q

Which of the following factors contributes to the highly exergonic nature of ATP hydrolysis?
A. removal of phosphate from the cytoplasm
B. addition of water to the hydrophilic ATP molecule
C. decrease in negative-ion repulsion in ATP
D. low energy of activation for the hydrolysis
E. none of the above

A

C. decrease in negative-ion repulsion in ATP

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20
Q

Where does ATP hydrolysis rank among the standard free energies of phosphoryl group transfer of all biological molecules?
A. ATP hydrolysis has nearly the largest negative free energy change.
B. ATP hydrolysis has an intermediate free energy change.
C. ATP hydrolysis has the largest negative free energy change.
D. ATP hydrolysis has nearly the smallest negative free energy change.

A

B. ATP hydrolysis has an intermediate free energy change.

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21
Q 
The activity of the glycolytic enzyme phosphofructokinase-1 is increased by which one of the following molecules?
A.  Fructose-2,6-bisphosphate
B.  Fructose-1,6-bisphosphate
C.  ATP
D.  Fructose-6-phosphate
A

A. Fructose-2,6-bisphosphate

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22
Q

What is the typical fate of pyruvate in red blood cells?
A. Converted to ethanol and CO2.
B. Used to produce glucose via gluconeogenesis.
C. Completely oxidized to CO2 and H2O.
D. Reduced to produce lactate.

A

D. Reduced to produce lactate.

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23
Q

Which statement completes the following sentence correctly? The reactions in glycolysis catalyzed by phosphofructokinase-1 and pyruvate kinase are similar in that:
A. they are both reversible.
B. they both use ATP.
C. they are both substrate-level phosphorylation reactions.
D. they both involve three-carbon compounds.
E. they are both catalyzed by allosteric enzymes.

A

E. they are both catalyzed by allosteric enzymes.

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24
Q 
Which enzyme catalyzes a regulated step in glycolysis and is affected by insulin?
A. Hexokinase
B. Phosphofructokinase-2
C. Fructose-1,6-bisphosphatase
D. Phosphofructokinase-1
Both C and D are correct.
A

D. Phosphofructokinase-1

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25
Q

Pyruvate has several metabolic fates depending on the cell, under aerobic or anaerobic conditions. Which one of the following is a metabolic fate for pyruvate?
A. decarboxylation to oxaloacetate
B. oxidation to ethanol
C. oxidative carboxylation to acetyl-CoA
D. reduction to lactate

A

D. reduction to lactate

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26
Q 
Which of the following is NOT a direct product of pyruvate metabolism?
A. Acetyl-CoA
B. Lactate
C. Oxaloacetate
D. Phosphoenolpyruvate
E.  Both C and D are correct.
A

D. Phosphoenolpyruvate

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27
Q 
Which one of the following enzymes catalyzes an "energy investment" reaction in glycolysis?
A. Hexokinase
B. Phosphofructokinase-2
C. Pyruvate kinase
D. Phosphoglycerate kinase
E.  Both A and B are correct.
A

A. Hexokinase

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28
Q

Which of the following is a reversible reaction under cellular conditions?
A. Fructose-6-phosphate + ATP ——> Fructose-1,6 bisphosphate + ADP + H+
B. Glucose-6-phosphate + H2O —–> Glucose + Pi
C. Phosphoenolpyruvate + ADP + H+ —–> Pyruvate + ATP
D. 1,3-bisphosphoglycerate + ADP ——> 3-phosphoglycerate + ATP

A

D. 1,3-bisphosphoglycerate + ADP ——> 3-phosphoglycerate + ATP

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29
Q

Consider the following metabolic reaction:

1,3-bisphosphoglycerate + NADH + H+ —> Glyceraldehyde-3-phosphate + NAD+ + Pi

Which of the following statements is TRUE?

i) This reaction is irreversible in the cell.
ii) This reaction is catalyzed by an isomerase.
iii) This reaction proceeds in the opposite direction during gluconeogenesis.
iv) This reaction is a redox reaction.
A. ii only
B. i, ii, and iii
C. iv only
D. All of the statements are true

A

C. iv only

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30
Q

If pyruvate could not be converted to lactate in muscle cells during strenuous exercise, what would be the outcome?
A. The rate of gluconeogenesis will increase.
B. Glycolysis would stop.
C. The muscle cell would export pyruvate out of the cell.
D. Glycolysis would be more efficient.

A

B. Glycolysis would stop.

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31
Q

What is the most likely fate of pyruvate in mammalian muscle during very vigorous exercise?
A. Conversion to oxaloacetate, to replenish citric acid cycle intermediates via anaplerotic reactions.
B. Transport out of the muscle cell into the bloodstream.
C. Conversion to lactate via lactate dehydrogenase.
D. Conversion to acetyl-CoA via the pyruvate dehydrogenase complex.

A

C. Conversion to lactate via lactate dehydrogenase.

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32
Q

What is the biochemical purpose for the production of lactate in muscle cells?
A. It is produced to reoxidize cytoplasmic NADH under anaerobic conditions
B. It decreases the pH of the muscle cell, thereby increasing release of oxygen from hemolglobin.
C. Its production enhances the activity of the citric acid cycle.
D. It is produced as a fuel molecule for the Cori cycle.
E. It replaces pyruvate as a substrate for the pyruvate dehydrogenase complex.

A

A. It is produced to reoxidize cytoplasmic NADH under anaerobic conditions

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33
Q

Which of the following statements is TRUE regarding glycogen synthase?
A. It uses glucose-1-phosphate as a substrate.
B. It is activated by protein kinases.
C. It is activated by Ca2+ ions.
D. It catalyzes formation of glycosidic bonds.

A

D. It catalyzes formation of glycosidic bonds.

34
Q

Which one of the following processes most completely describes phosphorolysis reactions?
A. Hydrolyzing a polymer and adding a phosphate group.
B. Splitting a polymer.
C. Splitting a polymer and adding a phosphate group.
D. Removing a phosphate group from a polymer.

A

C. Splitting a polymer and adding a phosphate group.

35
Q

Which of the following statements regarding gluconeogenesis is TRUE?
A. Fructose-2,6-bisphosphate activates gluconeogenesis.
B. The conversion of phosphoenolpyruvate to 2-phosphoglycerate occurs in two steps.
C. It is likely to occur when cellular ATP levels are high.
D. It occurs actively in skeletal muscle during periods of exercise.
E. Gluconeogenesis is reciprocally regulated with glycogen synthesis.

A

C. It is likely to occur when cellular ATP levels are high.

36
Q 
Which of the following compounds is NOT a substrate for the synthesis of glucose via gluconeogenesis?
A.  leucine
B.  oxaloacetate
C.  lactate
D.  alanine
E.  glycerol
A

A. leucine

37
Q

Which of the following statements about glycogen is FALSE?
A. It consists of glucose residues linked by (1-6)- and (1-4)-glycosidic bonds.
B. Glycogen signals the fasting state and is released into the bloodstream when blood sugar levels are low.
C. It allows for the storage of many glucose molecules.
D. UDP-glucose is an “activated” compound that can donate a glucose molecule to a growing glycogen chain.

A

B. Glycogen signals the fasting state and is released into the bloodstream when blood sugar levels are low.

38
Q

Which of the following statements regarding gluconeogenesis is TRUE?
A. It primarily occurs in the liver.
B. It is catalyzed by all the same enzymes as glycolysis.
C. It leads to the synthesis of glucose in muscle tissue.
D. Both A and C are correct.

A

A. It primarily occurs in the liver.

39
Q

In humans, which one of the following statements regarding gluconeogenesis is FALSE?
A. Gluconeogenesis is activated by glucagon.
B. Gluconeogenesis is activated when ADP levels are high.
C. Gluconeogenesis requires the enzyme glucose-6-phosphatase.
D. Gluconeogenesis helps to maintain blood glucose levels between meals.

A

B. Gluconeogenesis is activated when ADP levels are high.

40
Q 
NADPH used in lipid biosynthesis is produced in \_\_\_\_\_.
A.  the pentose phosphate pathway 
B.  the citric acid cycle 
C.  glycolysis 
D.  gluconeogenesis 
E.  none of the above
A

A. the pentose phosphate pathway

41
Q 
Which of the following requires large amounts of both ribose-5-phosphate and NADPH?
A.  amino acid synthesis 
B.  DNA synthesis 
C.  lipid synthesis 
D.  glycogen synthesis 
E.  cholesterol synthesis
A

B. DNA synthesis

42
Q 
Which one of the following would not be involved in the equation that describes the oxidative decarboxylation of pyruvate?
A.  ATP
B.  NADH
C.  HS-CoA
D.  NAD+
E.  CO2
A

A. ATP

43
Q

Which three of the following are possible sources for acetyl-CoA that enters the citric acid cycle?

1) oxidative decarboxylation of pyruvate
2) β oxidation of fatty acids
3) catabolism of certain amino acids
4) citrate
5) carboxylation of pyruvate
A. 1, 2 and 4
B. 1, 2 and 3
C. 1, 2 and 5
D. 2, 3 and 4
E. 1, 4 and 5

A

B. 1, 2 and 3

44
Q

The rate of the citric acid cycle would be INCREASED under which of the following conditions?
A. The ADP/ATP ratio is high.
B. The ADP/ATP ratio is low.
C. The NAD+/NADH ratio is low.
D. The concentration of oxaloacetate is low.
E. B and C.

A

A. The ADP/ATP ratio is high.

45
Q

Under which of the following conditions is the entry of acetyl-CoA into the citric acid cycle DECREASED?
A. When the NADH/NAD+ ratio is high.
B. When NAD+ levels are elevated.
C. When the ADP/ATP ratio is high.
D. When NADH is rapidly oxidized via the electron transport system.
E. When ADP levels are elevated.

A

A. When the NADH/NAD+ ratio is high.

46
Q 
If an organism were fed a diet consisting of lactate, PEP and acetyl-CoA, the energy yield per mole from the complete catabolism of these molecules would be in which order (highest to lowest)?
A.  acetyl-CoA > PEP > lactate
B.  acetyl-CoA > lactate > PEP
C.  PEP > acetyl-CoA > lactate
D.  PEP > lactate > acetyl-CoA
E.  lactate > PEP > acetyl-CoA
A

E. lactate > PEP > acetyl-CoA

47
Q 
Which of the following can be converted into glutamic acid in a single enzyme-catalyzed step?
A.  malate 
B.  alpha-ketoglutarate 
C.  succinyl-CoA 
D.  isocitrate 
E.  oxaloacetate
A

B. alpha-ketoglutarate

48
Q

Match each of the following:

Glycogen
Pyruvate 
2 CO2 
Acetyl groups 
Citric acid cycle
  1. Product of one complete round of the citric acid cycle
  2. Glucose residues linked together
  3. Oxidizes Acetyl groups to carbon dioxide
  4. The final result of glycolysis
  5. Two-carbon fragments derived from carbohydrates, amino acids, and fatty acids, and enter the citric acid cycle
A

Glycogen 2. Glucose residues linked together
Pyruvate 4. The final result of glycolysis
2 CO2 1. Product of one complete round of the citric acid cycle
Acetyl groups 5. Two-carbon fragments derived from carbohydrates, amino acids, and fatty acids, and enter the citric acid cycle
Citric acid cycle 3. Oxidizes Acetyl groups to carbon dioxide

49
Q

In adipocytes, why does the synthesis of triacylglycerols require an external supply of glucose?
A. The synthesis of triacylglycerols requires glycerol, which is derived from glucose.
B. The synthesis of triacylglycerols requires glycerol 3-phosphate, which is derived from glucose.
C. Glucose is required for the production of acetyl-CoA, which is necessary for the synthesis of fatty acids.
D. Glucose is required for the anaerobic production of ATP.

A

B. The synthesis of triacylglycerols requires glycerol 3-phosphate, which is derived from glucose.

50
Q

Which of these statements about cholesterol synthesis is NOT true?
A. Statins are competitive inhibitors of HMG-CoA reductase.
B. Unregulated cholesterol synthesis predisposes humans to development of atherosclerotic plaques.
C. Glucagon inhibits HMG-CoA reductase activity.
D. Dietary cholesterol has little effect on the synthesis of cholesterol in hepatocytes.

A

D. Dietary cholesterol has little effect on the synthesis of cholesterol in hepatocytes.

51
Q

Why is HDL commonly referred to as “good cholesterol”?
A. It returns excess cholesterol from peripheral tissues to the intestine where it can be excreted as bile salts.
B. It returns excess cholesterol from the intestine to the liver where it can be stored as bile salts.
C. It returns excess cholesterol from peripheral tissues to the liver where it can be excreted as bile salts.
D. It returns excess cholesterol from adipocytes to the liver where it can be stored as bile salts.

A

C. It returns excess cholesterol from peripheral tissues to the liver where it can be excreted as bile salts.

52
Q

Fat is a more efficient store of energy than carbohydrate. Which of the following is NOT a factor in this?
A. Fatty acids are more highly reduced than carbohydrates.
B. Per gram, fatty acids contain twice as many calories as glucose.
C. Fat is catabolized only aerobically; carbohydrate can be catabolized anaerobically.
D. Carbohydrates are polar, hydrophilic molecules.

A

C. Fat is catabolized only aerobically; carbohydrate can be catabolized anaerobically.

53
Q 
Where are the two major sites for fatty acid catabolism in the body?
A.  Liver and cardiac muscle.
B.  Liver and skeletal muscle.
C.  Skeletal muscle and adipose tissue.
D.  Liver and adipose tissue.
A

B. Liver and skeletal muscle.

54
Q

“Statins” are pharmaceutical drugs designed to inhibit which enzyme/pathway?
A. lipoprotein lipase/lipolysis
B. acetyl-CoA carboxylase/fatty acid synthesis
C. HMG-CoA reductase/cholesterol synthesis
D. carnitine acyltransferase/-oxidation
E. transaminase/urea cycle

A

C. HMG-CoA reductase/cholesterol synthesis

55
Q 
The hydrolysis of triacylglycerols stored in adipose tissue is catalyzed by the enzyme \_\_\_\_\_.
A.  lipoprotein lipase 
B.  chylomicron lipase 
C.  adipocyte lipase 
D.  albumin-associated lipase 
E.  hormone-sensitive lipase
A

E. hormone-sensitive lipase

56
Q 
What transport system moves activated fatty acids from the cytosol to the mitochondrial matrix?
A.  glycerol phosphate shuttle 
B.  carnitine shuttle 
C.  triacylglycerol shuttle 
D.  acyl adenylate shuttle 
E.  lipoprotein shuttle
A

B. carnitine shuttle

57
Q 
What coenzyme is required for the complete β-oxidation of a polyunsaturated fatty acid?
A.  NADPH 
B.  NADP+ 
C.  NADH 
D.  FADH2 
E.  all of the above
A

A. NADPH

58
Q

Which of the following types of fatty acids would be oxidized exclusively in the peroxisome instead of the mitochondria?
A. branched-chain fatty acids
B. polyunsaturated fatty acids
C. monounsaturated fatty acids
D. short-chain saturated fatty acids
E. very long-chain saturated fatty acids

A

A. branched-chain fatty acids

59
Q

The synthesis of triacylglycerols involves the addition of acyl groups to glycerol-3-phosphate. What is the source of the acyl groups?
A. free fatty acid
B. acyl-carnitine
C. fatty acid attached to the acyl carrier protein
D. fatty acyl-CoA
E. fatty acyladenylate

A

D. fatty acyl-CoA

60
Q 
Which of the lipoproteins is responsible for removing cholesterol from cells?
A.  VHDL 
B.  chylomicron 
C.  LDL 
D.  VLDL 
E.  HDL
A

E. HDL

61
Q

What are the products of the following transamination reaction?

alpha-ketoglutarate + alanine  \_\_\_\_\_ + \_\_\_\_\_
A.  aspartate; oxaloacetate 
B.  glutamate; oxaloacetate 
C.  aspartate; pyruvate 
D.  glutamate; pyruvate 
E.  none of the above
A

D. glutamate; pyruvate

62
Q 
Which of the following citric acid cycle intermediates can be converted to aspartate via transamination?
A.  fumarate 
B. alpha-ketoglutarate 
C.  citrate 
D.  oxaloacetate
A

D. oxaloacetate

63
Q 
Which of the following glycolytic intermediates is the common precursor to serine, cysteine and glycine?
A.  pyruvate 
B.  fructose-6-phosphate 
C.  dihydroxyacetone phosphate 
D.  glyceraldehyde-3-phosphate 
E.  3-phosphoglycerate
A

E. 3-phosphoglycerate

64
Q

What step controls the activity of both purine and pyrimidine synthesis?
A. conversion of UTP to CTP
B. conversion of IMP to xanthosine monophosphate for GMP production
C. ribonucleotide reductase
D. conversion of IMP to adenylosuccinate for AMP production
E. conversion of ribose-5-phosphate to 5-phosphoribosyl pyrophosphate

A

E. conversion of ribose-5-phosphate to 5-phosphoribosyl pyrophosphate

65
Q 
Which of the following amino acids is a source of both carbon and nitrogen for UMP?
A.  Glu 
B.  Gly 
C.  Asp 
D.  Gln 
E.  Asn
A

C. Asp

66
Q

What nucleotide is methylated to produce dTMP?
A. dGMP
B. dAMP
C. both dCMP and dUMP can be converted to dTMP
D. dCMP
E. dUMP

A

E. dUMP

67
Q 
Which of the following is secreted from the pancreas when blood glucose levels are low?
A.  insulin
B.  glucose
C.  glucagon
D.  epinephrine
A

C. glucagon

68
Q 
Where are the two major sites of glucose storage in humans?
A.  Brain and kidney.
B.  Muscle and adipose tissue.
C.  Liver and adipose tissue.
D.  Liver and muscle.
E.  Liver and brain.
A

D. Liver and muscle.

69
Q 
Where are triacylglycerols stored in humans under normal conditions?
A.  Hepatocytes
B.  Myocytes
C.  Adipocytes
D.  Liver cells
A

C. Adipocytes

70
Q

Which of the following does NOT typically occur in response to the release of insulin?
A. Glycolysis in the liver.
B. Glycogen breakdown in skeletal muscle.
C. Glycogen synthesis in the liver.
D. Glycolysis in skeletal muscle.

A

B. Glycogen breakdown in skeletal muscle.

71
Q

Which of the following statements regarding insulin is FALSE?
A. Insulin results in a lowering of the blood glucose levels.
B. Insulin signals the fed state.
C. Insulin stimulates the liver to store fatty acids as triacylglycerols.
D. Insulin works through activating phosphatases.

A

C. Insulin stimulates the liver to store fatty acids as triacylglycerols.

72
Q

Which of the following does NOT correctly describe insulin’s role in human metabolism?
A. Insulin is released in response to high blood glucose.
B. Insulin activates phosphatases.
C. Insulin activates glycogenolysis.
D. Insulin results in fatty acids being stored as fat in adipocytes.

A

C. Insulin activates glycogenolysis.

73
Q 
In a well-fed state, brain cells use which one of the following compounds circulating in the blood stream almost exclusively as an energy source?
A.  amino acids
B.  insulin
C.  glucose
D.  ketone bodies
E.  fatty acids
A

C. glucose

74
Q

What are the two major types of fuel store in mammals?
A. Fat and skeletal muscle proteins.
B. Glycogen and skeletal muscle proteins.
C. Fat and glycogen.
D. Ketones and glycogen.

A

C. Fat and glycogen.

75
Q 
Mammalian cells derive chemical energy from a variety of "fuel" molecules which are delivered to them in the bloodstream. Which one of the following is NEVER taken up as a fuel molecule from the bloodstream?
A.  Acetyl-CoA
B.  Acetoacetate
C.  Glucose
D.  Fatty acids
E.  Lactate
A

A. Acetyl-CoA (not transported in the blood stream)

76
Q 
What metabolite is used in unusually high amounts by cancerous tumors and is thus often used as a means to visualize cancerous tissue?
A.  very long chain fatty acids 
B.  lactate 
C.  ketone bodies 
D.  glutamine 
E.  glucose
A

E. glucose

77
Q 
Under anaerobic conditions, \_\_\_\_\_ is produced in the muscle and is then used by the liver for \_\_\_\_\_.
A.  citrate; fatty acid synthesis 
B.  glycogen; glycogenolysis 
C.  lactate; gluconeogenesis 
D.  glycerol; triacylglycerol synthesis 
E.  oxaloacetate; gluconeogenesis
A

C. lactate; gluconeogenesis

78
Q 
After several days of fasting, the liver begins producing relatively large amounts of ketone bodies. Which type of tissue is highly dependent upon this as its sole source of energy in the absence of glucose?
A.  heart 
B.  kidney 
C.  skeletal muscle 
D.  brain 
E.  all of the above
A

D. brain

79
Q 
In a diabetic liver, which of the following pathways would be constantly active?
A.  ketone body oxidation 
B.  glycolysis 
C.  glycogen synthesis 
D.  fatty acid synthesis 
E.  gluconeogenesis
A

E. gluconeogenesis

80
Q 
The synthesis of what liver enzyme is inhibited by the drug metformin, an activator of AMPK?
A.  pyruvate carboxylase 
B.  glucose-6-phosphatase 
C.  phosphofructokinase 
D.  glycogen phosphorylase 
E.  acetyl-CoA carboxylase
A

B. glucose-6-phosphatase

Biochemistry Test 3 (3 decks)

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