Question 1

Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements correctly describes phosphofructokinase activity?

Accepted Answer

A)  It is inhibited by AMP.
B)  It is activated by ATP.
C)  It is activated by citrate, an intermediate of the citric acid cycle.
D)  It catalyzes the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate, an early step of glycolysis.
E)  It is an allosteric enzyme.F) C) and E)
G) C) and D)

Question 2

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of

Accepted Answer

A)  active transport.
B)  an endergonic reaction coupled to an exergonic reaction.
C)  a reaction with a positive ΔG.
D)  osmosis.
E)  allosteric regulation.F) C) and D)
G) C) and E)

Question 3

During respiration, energy flows in the following sequence.

Accepted Answer

A)  glucose → NADH → electron transport → oxygen
B)  glucose → electron transport → NADH → proton-motive force → ATP
C)  pyruvate → acetyl-CoA → electron transport → water
D)  glucose → pyruvate → acetyl-CoA → CO₂
E)  glucose → NADH → electron transport → proton-motive force → ATPF) D) and E)
G) A) and B)

Question 4

What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source?

Accepted Answer

A)  1/6
B)  1/3
C)  1/2
D)  2/3
E)  100/100F) A) and B)
G) A) and E)

Question 5

When skeletal muscle cells are oxygen-deprived, the heart still pumps. What must the heart muscle cells be able to do?

Accepted Answer

A)  derive sufficient energy from fermentation
B)  continue aerobic metabolism when skeletal muscle cannot
C)  transform lactate to pyruvate again
D)  remove lactate from the blood
E)  remove oxygen from lactateF) A) and D)
G) D) and E)

Question 6

Where is ATP synthase located in the mitochondrion?

Accepted Answer

A)  cytosol
B)  electron transport chain
C)  outer membrane
D)  inner membrane
E)  mitochondrial matrixF) B) and C)
G) A) and B)

Question 7

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes

Accepted Answer

A)  hydrolyzed.
B)  hydrogenated.
C)  oxidized.
D)  reduced.
E)  an oxidizing agent.F) C) and D)
G) D) and E)

Question 8

The free energy for the oxidation of glucose to CO₂ and water is -686 kcal/mol and the free energy for the reduction of NAD⁺ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?

Accepted Answer

A)  Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis.
B)  Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat.
C)  Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
D)  There is no CO₂ or water produced as products of glycolysis.
E)  Glycolysis consists of many enzymatic reactions, each of which extracts some energy from the glucose molecule.F) A) and C)
G) None of the above

Question 9

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

Accepted Answer

A)  The pH of the matrix increases.
B)  ATP synthase pumps protons by active transport.
C)  The electrons gain free energy.
D)  The cytochromes phosphorylate ADP to form ATP.
E)  NAD⁺ is oxidized.F) D) and E)
G) A) and E)

Question 10

Why is glycolysis described as having an investment phase and a payoff phase?

Accepted Answer

A)  It both splits molecules and assembles molecules.
B)  It attaches and detaches phosphate groups.
C)  It uses glucose and generates pyruvate.
D)  It shifts molecules from cytosol to mitochondrion.
E)  It uses stored ATP and then forms a net increase in ATP.F) A) and E)
G) B) and C)

Question 11

During intense exercise, as skeletal muscle cells go into anaerobiosis, the human body will increase its catabolism of

Accepted Answer

A)  fats only.
B)  carbohydrates only.
C)  proteins only.
D)  fats, carbohydrates, and proteins.
E)  fats and proteins only.F) A) and D)
G) B) and E)

Question 12

What is the purpose of beta oxidation in respiration?

Accepted Answer

A)  oxidation of glucose
B)  oxidation of pyruvate
C)  feedback regulation
D)  control of ATP accumulation
E)  breakdown of fatty acidsF) D) and E)
G) B) and D)

Question 13

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

Accepted Answer

A)  oxygen.
B)  water.
C)  NAD⁺.
D)  pyruvate.
E)  ADP.F) A) and B)
G) A) and D)

Question 14

Why are carbohydrates and fats considered high-energy foods?

Accepted Answer

A)  They have a lot of oxygen atoms.
B)  They have no nitrogen in their makeup.
C)  They can have very long carbon skeletons.
D)  They have a lot of electrons associated with hydrogen.
E)  They are easily reduced.F) C) and D)
G) None of the above

Question 15

In addition to ATP, what are the end products of glycolysis?

Accepted Answer

A)  CO₂ and H₂O
B)  CO₂ and pyruvate
C)  NADH and pyruvate
D)  CO₂ and NADH
E)  H₂O, FADH₂, and citrateF) B) and D)
G) B) and C)

Question 16

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to

Accepted Answer

A)  inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.
B)  activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle.
C)  inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle.
D)  activate the enzyme and increase the rates of glycolysis and the citric acid cycle.
E)  inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate.F) C) and D)
G) C) and E)

Question 17

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

Accepted Answer

A)  the citric acid cycle
B)  the electron transport chain
C)  glycolysis
D)  synthesis of acetyl CoA from pyruvate
E)  reduction of pyruvate to lactateF) B) and E)
G) B) and D)

Question 18

The figure below illustrates some of the steps (reactions)  of glycolysis in their proper sequence. Each step is lettered. Use these letters to answer the questions.
 
-Which step in the figure above is a redox reaction?

Accepted Answer

A)  A
B)  B
C)  C
D)  D
E)  EF) A) and E)
G) A) and D)

Question 19

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the

Accepted Answer

A)  formation of ATP.
B)  reduction of NAD⁺.
C)  restoration of the Na⁺/K⁺ balance across the membrane.
D)  creation of a proton-motive force.
E)  lowering of pH in the mitochondrial matrix.F) All of the above
G) A) and B)

Question 20

What is the term for metabolic pathways that release stored energy by breaking down complex molecules?

Accepted Answer

A)  anabolic pathways
B)  catabolic pathways
C)  fermentation pathways
D)  thermodynamic pathways
E)  bioenergetic pathwaysF) All of the above
G) B) and D)

Exam 9: Cellular Respiration and Fermentation

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to

Correct AnswerverifiedShow Answer

Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements correctly describes phosphofructokinase activity?

Correct AnswerverifiedShow Answer

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes

Correct AnswerverifiedShow Answer

What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source?

Correct AnswerverifiedShow Answer

Why is glycolysis described as having an investment phase and a payoff phase?

Correct AnswerverifiedShow Answer

Why are carbohydrates and fats considered high-energy foods?

Correct AnswerverifiedShow Answer

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of

Correct AnswerverifiedShow Answer

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

Correct AnswerverifiedShow Answer

Where is ATP synthase located in the mitochondrion?

Correct AnswerverifiedShow Answer

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

Correct AnswerverifiedShow Answer

The figure below illustrates some of the steps (reactions) of glycolysis in their proper sequence. Each step is lettered. Use these letters to answer the questions. -Which step in the figure above is a redox reaction?

Correct AnswerverifiedShow Answer

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

Correct AnswerverifiedShow Answer

When skeletal muscle cells are oxygen-deprived, the heart still pumps. What must the heart muscle cells be able to do?

Correct AnswerverifiedShow Answer

What is the term for metabolic pathways that release stored energy by breaking down complex molecules?

Correct AnswerverifiedShow Answer

The free energy for the oxidation of glucose to CO₂ and water is -686 kcal/mol and the free energy for the reduction of NAD⁺ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?

Correct AnswerverifiedShow Answer

In addition to ATP, what are the end products of glycolysis?

Correct AnswerverifiedShow Answer

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the

Correct AnswerverifiedShow Answer

During respiration, energy flows in the following sequence.

Correct AnswerverifiedShow Answer

What is the purpose of beta oxidation in respiration?

Correct AnswerverifiedShow Answer

During intense exercise, as skeletal muscle cells go into anaerobiosis, the human body will increase its catabolism of

Correct AnswerverifiedShow Answer

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