Question 1

The citric acid cycle is considered part of aerobic metabolism even though oxygen does not appear explicitly in any reaction because

Accepted Answer

A)  the NADH and FADH2 produced are reoxidized in the electron transport chain linked to oxygen 
B)  the reoxidation of NADH and FADH2 leads to the production of considerable quantities of ATP 
C)  it takes place in the mitochondrion 
D)  it contains oxidation reactions 
A)  the NADH and FADH2 produced are reoxidized in the electron transport chain linked to oxygen 
B)  the reoxidation of NADH and FADH2 leads to the production of considerable quantities of ATP 
C)  it takes place in the mitochondrion 
D)  it contains oxidation reactions

Question 2

Which of the following does not play a role in the overall aerobic metabolism of glucose?

Accepted Answer

A)  citric acid cycle 
B)  electron transport 
C)  oxidative phosphorylation 
D)  urea cycle 
E)  all of these play a role in overall aerobic metabolism of glucose 
A)  citric acid cycle 
B)  electron transport 
C)  oxidative phosphorylation 
D)  urea cycle 
E)  all of these play a role in overall aerobic metabolism of glucose

Question 3

Which of the following is a source of NADPH?

Accepted Answer

A)  the pentose phosphate pathway 
B)  a series of reactions in which oxaloacetate is reduced to malate followed by oxidative decarboxylation of the malate to pyruvate 
C)  both of the above 
D)  neither of these 
A)  the pentose phosphate pathway 
B)  a series of reactions in which oxaloacetate is reduced to malate followed by oxidative decarboxylation of the malate to pyruvate 
C)  both of the above 
D)  neither of these

Question 4

The citric acid cycle is amphibolic, meaning

Accepted Answer

A)  it plays a role in both anabolism and catabolism. 
B)  it is essentially irreversible. 
C)  it can operate both in the presence and absence of oxygen. 
D)  it can oxidize carbons and nitrogens equally well. 
E)  none of these 
A)  it plays a role in both anabolism and catabolism. 
B)  it is essentially irreversible. 
C)  it can operate both in the presence and absence of oxygen. 
D)  it can oxidize carbons and nitrogens equally well. 
E)  none of these

Question 5

Which of the following describes a use for acetyl-CoA as an important intermediate in metabolism?

Accepted Answer

A)  Breakdown to CO2 and water, yielding much energy. 
B)  Synthesis of terpenes and steroids. 
C)  Synthesis of oxaloacetate in plants. 
D)  Synthesis of fatty acids. 
E)  All of these are reasons why acetyl-CoA is a central molecule in metabolism. 
A)  Breakdown to CO2 and water, yielding much energy. 
B)  Synthesis of terpenes and steroids. 
C)  Synthesis of oxaloacetate in plants. 
D)  Synthesis of fatty acids. 
E)  All of these are reasons why acetyl-CoA is a central molecule in metabolism.

Question 6

In muscle cells, the following reaction proceeds as written, i.e. , from left to right, despite having Δ G ° ' ≈ +30 kJ\mol. How can this occur?
Malate + NAD+ → oxaloacetate + NADH + H+

Accepted Answer

A)  It is obviously thermodynamically favored under standard conditions. 
B)  In the cell, it is kinetically favored, even though it's thermodynamically unfavored. 
C)  The concentration of malate must be higher than oxaloacetate for this reaction to occur in the cell. 
D)  [H+] must be higher in muscle than under standard conditions, thus altering Δ G ° ' to Δ G ° . 
A)  It is obviously thermodynamically favored under standard conditions. 
B)  In the cell, it is kinetically favored, even though it's thermodynamically unfavored. 
C)  The concentration of malate must be higher than oxaloacetate for this reaction to occur in the cell. 
D)  [H+] must be higher in muscle than under standard conditions, thus altering Δ G ° ' to Δ G ° .

Question 7

Which group of small molecules best fit the boxes associated with the reaction shown?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
A)  I 
B)  II 
C)  III 
D)  IV

Question 8

A cell in an active metabolic state has

Accepted Answer

A)  a high (ATP\ADP) and a high (NADH\NAD+) ratio. 
B)  a high (ATP\ADP) and a low (NADH\NAD+) ratio. 
C)  a low (ATP\ADP) and a low (NADH\NAD+) ratio. 
D)  a low (ATP\ADP) and a high (NADH\NAD+) ratio. 
A)  a high (ATP\ADP) and a high (NADH\NAD+) ratio. 
B)  a high (ATP\ADP) and a low (NADH\NAD+) ratio. 
C)  a low (ATP\ADP) and a low (NADH\NAD+) ratio. 
D)  a low (ATP\ADP) and a high (NADH\NAD+) ratio.

Question 9

​ Identify a true statement about lipoic acid.

Accepted Answer

A)  It contains two disulfide groups in its oxidized form and one sulfhydryl group in its reduced form. 
B)  It contains two disulfide groups in its reduced form and one sulfhydryl group in its oxidized form. 
C)  It contains one disulfide group in its reduced form and two sulfhydryl groups in its oxidized form. 
D)  It contains one disulfide group in its oxidized form and two sulfhydryl groups in its reduced form. 
A)  It contains two disulfide groups in its oxidized form and one sulfhydryl group in its reduced form. 
B)  It contains two disulfide groups in its reduced form and one sulfhydryl group in its oxidized form. 
C)  It contains one disulfide group in its reduced form and two sulfhydryl groups in its oxidized form. 
D)  It contains one disulfide group in its oxidized form and two sulfhydryl groups in its reduced form.

Question 10

Intermediates of the citric acid cycle are especially important in the synthesis of fatty acids and amino acids.

Accepted Answer

A) True 
 B)False

Question 11

The reaction in which malate is oxidized to oxaloacetate is not thermodynamically favored. It takes place because

Accepted Answer

A)  it is coupled to ATP hydrolysis. 
B)  it involves substrate-level phosphorylation. 
C)  the product is continuously used up in the next reaction of the cycle, which is thermodynamically favored. 
D)  it is coupled to a strong reduction. 
A)  it is coupled to ATP hydrolysis. 
B)  it involves substrate-level phosphorylation. 
C)  the product is continuously used up in the next reaction of the cycle, which is thermodynamically favored. 
D)  it is coupled to a strong reduction.

Question 12

Which of the following enzymes is allosterically activated by NAD+?

Accepted Answer

A)  isocitrate dehydrogenase 
B)  succinyl-CoA synthetase 
C)  succinate dehydrogenase 
D)  fumarase 
E)  none of these 
A)  isocitrate dehydrogenase 
B)  succinyl-CoA synthetase 
C)  succinate dehydrogenase 
D)  fumarase 
E)  none of these

Question 13

In the glyoxylate cycle, acetyl-CoA reacts with glyoxylate to produce

Accepted Answer

A)  succinyl-CoA 
B)  succinate 
C)  fumarate 
D)  malate 
A)  succinyl-CoA 
B)  succinate 
C)  fumarate 
D)  malate

Question 14

"Energy charge" in a cell is a measure of

Accepted Answer

A)  ATP\NAD+ ratios. 
B)  ATP\NADH ratios. 
C)  ATP\ADP ratios. 
D)  NADH\NAD+ ratios. 
E)  NAD+\ADP ratios. 
A)  ATP\NAD+ ratios. 
B)  ATP\NADH ratios. 
C)  ATP\ADP ratios. 
D)  NADH\NAD+ ratios. 
E)  NAD+\ADP ratios.

Question 15

Which of the following enzymes is not a control point of the citric acid cycle?

Accepted Answer

A)  citrate synthase 
B)  isocitrate dehydrogenase 
C)  aconitase 
D)  the α -ketoglutarate dehydrogenase complex 
A)  citrate synthase 
B)  isocitrate dehydrogenase 
C)  aconitase 
D)  the α -ketoglutarate dehydrogenase complex

Question 16

Which of the following enzymes is the only membrane-bound enzyme in the citric acid cycle?

Accepted Answer

A)  Aconitase. 
B)  Iso Citrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  Alpha -Ketoglutarate Dehydrogenase complex. 
A)  Aconitase. 
B)  Iso Citrate Dehydrogenase. 
C)  Succinate Dehydrogenase. 
D)  Malate Dehydrogenase. 
E)  Alpha -Ketoglutarate Dehydrogenase complex.

Question 17

Roughly how many more ATP's can be produced via the complete aerobic oxidation of glucose compared to that produced by glycolysis alone?

Accepted Answer

A)  twice as much 
B)  five times as much 
C)  fifteen times as much 
D)  thirty-two times as much 
E)  none of these 
A)  twice as much 
B)  five times as much 
C)  fifteen times as much 
D)  thirty-two times as much 
E)  none of these

Question 18

Exhibit 19A The following compounds are all intermediates in the citric acid cycle.   Refer to Exhibit 19A. Which intermediate does FAD oxidize?

Accepted Answer

A)  2 
B)  3 
C)  4 
D)  5 
E)  More than one of these is oxidized by FAD. 
A)  2 
B)  3 
C)  4 
D)  5 
E)  More than one of these is oxidized by FAD.

Question 19

The citric acid cycle produces one high energy phosphate molecule per cycle directly in the form of ____

Accepted Answer

A)  ATP 
B)  GTP 
C)  CTP 
D)  AMP 
E)  none of these 
A)  ATP 
B)  GTP 
C)  CTP 
D)  AMP 
E)  none of these

Question 20

The production of malate in the glyoxylate pathway is important, since it can be readily converted to phosphoenolpyruvate and then to sugars.

Accepted Answer

A) True 
 B)False

Exam 19: The Citric Acid Cycle

The citric acid cycle is considered part of aerobic metabolism even though oxygen does not appear explicitly in any reaction because

Which of the following does not play a role in the overall aerobic metabolism of glucose?

Which of the following is a source of NADPH?

The citric acid cycle is amphibolic, meaning

Which of the following describes a use for acetyl-CoA as an important intermediate in metabolism?

In muscle cells, the following reaction proceeds as written, i.e. , from left to right, despite having Δ G ° ' ≈ +30 kJ\mol. How can this occur? Malate + NAD+ → oxaloacetate + NADH + H+

Which group of small molecules best fit the boxes associated with the reaction shown?

A cell in an active metabolic state has

​ Identify a true statement about lipoic acid.

Intermediates of the citric acid cycle are especially important in the synthesis of fatty acids and amino acids.

The reaction in which malate is oxidized to oxaloacetate is not thermodynamically favored. It takes place because

Which of the following enzymes is allosterically activated by NAD+?

In the glyoxylate cycle, acetyl-CoA reacts with glyoxylate to produce

"Energy charge" in a cell is a measure of

Which of the following enzymes is not a control point of the citric acid cycle?

Which of the following enzymes is the only membrane-bound enzyme in the citric acid cycle?

Roughly how many more ATP's can be produced via the complete aerobic oxidation of glucose compared to that produced by glycolysis alone?

Exhibit 19A The following compounds are all intermediates in the citric acid cycle. Refer to Exhibit 19A. Which intermediate does FAD oxidize?

The citric acid cycle produces one high energy phosphate molecule per cycle directly in the form of ____

The production of malate in the glyoxylate pathway is important, since it can be readily converted to phosphoenolpyruvate and then to sugars.

Biochemistry and the Organization of Cells

Water the Solvent for Biochemical Reactions

Amino Acids and Peptides

The Three Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins Enzymes

The Behavior of Proteins Enzymes Mechanisms and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids How Structure Conveys Information

Biosynthesis of Nucleic Acids Replication

Transcription of the Genetic Code the Biosynthesis of Rna

Protein Synthesis Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses Cancer and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism Cellular Signaling

Filters

In muscle cells, the following reaction proceeds as written, i.e. , from left to right, despite having Δ G ° ' ≈ +30 kJ\mol. How can this occur? Malate + NAD⁺ → oxaloacetate + NADH + H⁺

Identify a true statement about lipoic acid.

Which of the following enzymes is allosterically activated by NAD⁺?