Question 1

How do dehydrogenases function?

Accepted Answer

A) They remove a pair of hydrogen atoms from the substrate. 
B) They remove a pair of proton atoms from the substrate. 
C) They transfer the kinetic energy from glucose to NAD⁺. 
D) They facilitate the fall of electrons down an energy gradient from glucose to NAD⁺. 
E) They reduce substrate to produce oxidized NADH. 
A) They remove a pair of hydrogen atoms from the substrate. 
B) They remove a pair of proton atoms from the substrate. 
C) They transfer the kinetic energy from glucose to NAD⁺. 
D) They facilitate the fall of electrons down an energy gradient from glucose to NAD⁺. 
E) They reduce substrate to produce oxidized NADH. A

Question 2

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

Accepted Answer

A) 0% 
B) 2% 
C) 10% 
D) 38% 
E) 100% 
A) 0% 
B) 2% 
C) 10% 
D) 38% 
E) 100% E

Question 3

The transport of pyruvate into mitochondria depends on the proton-motive force across the inner mitochondrial membrane.How does pyruvate enter the mitochondrion?

Accepted Answer

A) active transport 
B) diffusion 
C) facilitated diffusion 
D) through a channel 
E) through a pore 
A) active transport 
B) diffusion 
C) facilitated diffusion 
D) through a channel 
E) through a pore A

Question 4

Why does glucose oxidation occur in a series of steps?

Accepted Answer

A) One step wouldn't allow the energy released to be harnessed efficiently. 
B) It doesn't have to; it just happens to be that way. 
C) Glycolysis evolved first and steps were just added over time. 
D) Glucose cannot pass into the mitochondria and oxygen cannot enter the cytosol. 
E) Glucose is reduced, not oxidized. 
A) One step wouldn't allow the energy released to be harnessed efficiently. 
B) It doesn't have to; it just happens to be that way. 
C) Glycolysis evolved first and steps were just added over time. 
D) Glucose cannot pass into the mitochondria and oxygen cannot enter the cytosol. 
E) Glucose is reduced, not oxidized.

Question 5

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

Question 6

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

Accepted Answer

A) It produces much less ATP than does oxidative phosphorylation. 
B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms. 
C) It is found in prokaryotic cells but not in eukaryotic cells. 
D) It relies on chemiosmosis, which is a metabolic mechanism present only in the first cells' prokaryotic cells. 
E) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells. 
A) It produces much less ATP than does oxidative phosphorylation. 
B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms. 
C) It is found in prokaryotic cells but not in eukaryotic cells. 
D) It relies on chemiosmosis, which is a metabolic mechanism present only in the first cells' prokaryotic cells. 
E) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.

Question 7

Use the following figure to answer the questions below.
   
The citric acid cycle.
-If pyruvate oxidation is blocked,what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the figure above?

Accepted Answer

A) There will be no change in the levels of oxaloacetate and citric acid. 
B) Oxaloacetate will decrease and citric acid will accumulate. 
C) Oxaloacetate will accumulate and citric acid will decrease. 
D) Both oxaloacetate and citric acid will decrease. 
E) Both oxaloacetate and citric acid will accumulate. 
A) There will be no change in the levels of oxaloacetate and citric acid. 
B) Oxaloacetate will decrease and citric acid will accumulate. 
C) Oxaloacetate will accumulate and citric acid will decrease. 
D) Both oxaloacetate and citric acid will decrease. 
E) Both oxaloacetate and citric acid will accumulate.

Question 8

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) E 
A) A 
B) B 
C) C 
D) D 
E) E

Question 9

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 → ATP 
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 → ATP

Question 10

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. 
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.

Question 11

During glycolysis,when each molecule of glucose is catabolized to two molecules of pyruvate,most of the potential energy contained in glucose is

Accepted Answer

A) transferred to ADP, forming ATP. 
B) transferred directly to ATP. 
C) retained in the two pyruvates. 
D) stored in the NADH produced. 
E) used to phosphorylate fructose to form fructose 6-phosphate. 
A) transferred to ADP, forming ATP. 
B) transferred directly to ATP. 
C) retained in the two pyruvates. 
D) stored in the NADH produced. 
E) used to phosphorylate fructose to form fructose 6-phosphate.

Question 12

Which catabolic processes may have been used by cells on ancient Earth before free oxygen became available?

Accepted Answer

A) glycolysis and fermentation only 
B) glycolysis and the citric acid cycle only 
C) glycolysis, pyruvate oxidation, and the citric acid cycle 
D) oxidative phosphorylation only 
E) glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron acceptor other than oxygen 
A) glycolysis and fermentation only 
B) glycolysis and the citric acid cycle only 
C) glycolysis, pyruvate oxidation, and the citric acid cycle 
D) oxidative phosphorylation only 
E) glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron acceptor other than oxygen

Question 13

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

Question 14

Following glycolysis and the citric acid cycle,but before the electron transport chain and oxidative phosphorylation,the carbon skeleton of glucose has been broken down to CO₂ with some net gain of ATP.However,what is most of the energy from the original glucose molecule at that point in the process in the form of?

Accepted Answer

A) acetyl-CoA 
B) glucose 
C) pyruvate 
D) NADH 
E) FADH₂ 
A) acetyl-CoA 
B) glucose 
C) pyruvate 
D) NADH 
E) FADH₂

Question 15

A mutation in yeast makes it unable to convert pyruvate to ethanol.How will this mutation affect these yeast cells?

Accepted Answer

A) The mutant yeast will be unable to grow anaerobically. 
B) The mutant yeast will grow anaerobically only when given glucose. 
C) The mutant yeast will be unable to metabolize glucose. 
D) The mutant yeast will die because they cannot regenerate NAD⁺ from NAD. 
E) The mutant yeast will metabolize only fatty acids. 
A) The mutant yeast will be unable to grow anaerobically. 
B) The mutant yeast will grow anaerobically only when given glucose. 
C) The mutant yeast will be unable to metabolize glucose. 
D) The mutant yeast will die because they cannot regenerate NAD⁺ from NAD. 
E) The mutant yeast will metabolize only fatty acids.

Question 16

Use the following figure to answer the questions below.
   
The citric acid cycle.
-Starting with citrate,which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the figure above)?

Accepted Answer

A) 1 ATP, 2 CO₂, 3 NADH, and 1 FADH₂ 
B) 2 ATP, 2 CO₂, 3 NADH, and 3 FADH₂ 
C) 3 ATP, 3 CO₂, 3 NADH, and 3 FADH₂ 
D) 3 ATP, 6 CO₂, 9 NADH, and 3 FADH₂ 
E) 38 ATP, 6 CO₂, 3 NADH, and 12 FADH₂ 
A) 1 ATP, 2 CO₂, 3 NADH, and 1 FADH₂ 
B) 2 ATP, 2 CO₂, 3 NADH, and 3 FADH₂ 
C) 3 ATP, 3 CO₂, 3 NADH, and 3 FADH₂ 
D) 3 ATP, 6 CO₂, 9 NADH, and 3 FADH₂ 
E) 38 ATP, 6 CO₂, 3 NADH, and 12 FADH₂

Question 17

Even though plants carry on photosynthesis,plant cells still use their mitochondria for oxidation of pyruvate.When and where will this occur?

Accepted Answer

A) in photosynthetic cells in the light, while photosynthesis occurs concurrently 
B) in nonphotosynthesizing cells only 
C) in cells that are storing glucose only 
D) in all cells all the time 
E) in photosynthesizing cells in the light and in other tissues in the dark 
A) in photosynthetic cells in the light, while photosynthesis occurs concurrently 
B) in nonphotosynthesizing cells only 
C) in cells that are storing glucose only 
D) in all cells all the time 
E) in photosynthesizing cells in the light and in other tissues in the dark

Question 18

Canine phosphofructokinase (PFK)deficiency afflicts Springer spaniels,affecting an estimated 10% of the breed.What is one implication of the genetic defect resulting in PFK deficiency in dogs?

Accepted Answer

A) early embryonic mortality 
B) elevated blood-glucose levels in the dog's blood 
C) an intolerance for exercise 
D) a reduced life span 
E) an increase in glycolysis 
A) early embryonic mortality 
B) elevated blood-glucose levels in the dog's blood 
C) an intolerance for exercise 
D) a reduced life span 
E) an increase in glycolysis

Question 19

In mitochondria,exergonic redox reactions

Accepted Answer

A) are the source of energy driving prokaryotic ATP synthesis. 
B) are directly coupled to substrate-level phosphorylation. 
C) provide the energy that establishes the proton gradient. 
D) reduce carbon atoms to carbon dioxide. 
E) are coupled via phosphorylated intermediates to endergonic processes. 
A) are the source of energy driving prokaryotic ATP synthesis. 
B) are directly coupled to substrate-level phosphorylation. 
C) provide the energy that establishes the proton gradient. 
D) reduce carbon atoms to carbon dioxide. 
E) are coupled via phosphorylated intermediates to endergonic processes.

Question 20

Which of the following normally occurs regardless of whether or not oxygen (O)is present?

Accepted Answer

A) glycolysis 
B) fermentation 
C) oxidation of pyruvate to acetyl CoA 
D) citric acid cycle 
E) oxidative phosphorylation (chemiosmosis) 
A) glycolysis 
B) fermentation 
C) oxidation of pyruvate to acetyl CoA 
D) citric acid cycle 
E) oxidative phosphorylation (chemiosmosis)

Exam 9: Cellular Respiration and Fermentation

How do dehydrogenases function?

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

The transport of pyruvate into mitochondria depends on the proton-motive force across the inner mitochondrial membrane.How does pyruvate enter the mitochondrion?

Why does glucose oxidation occur in a series of steps?

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

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

Use the following figure to answer the questions below. The citric acid cycle. -If pyruvate oxidation is blocked,what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the figure above?

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?

During respiration,energy flows in the following sequence.

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?

During glycolysis,when each molecule of glucose is catabolized to two molecules of pyruvate,most of the potential energy contained in glucose is

Which catabolic processes may have been used by cells on ancient Earth before free oxygen became available?

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?

A mutation in yeast makes it unable to convert pyruvate to ethanol.How will this mutation affect these yeast cells?

Use the following figure to answer the questions below. The citric acid cycle. -Starting with citrate,which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the figure above)?

Even though plants carry on photosynthesis,plant cells still use their mitochondria for oxidation of pyruvate.When and where will this occur?

Canine phosphofructokinase (PFK)deficiency afflicts Springer spaniels,affecting an estimated 10% of the breed.What is one implication of the genetic defect resulting in PFK deficiency in dogs?

In mitochondria,exergonic redox reactions

Which of the following normally occurs regardless of whether or not oxygen (O)is present?

Introduction: Evolution and Themes of Biology

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure,Growth,and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons,Synapses,and Signalling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behaviour

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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