Deck 22: Aerobic Respiration and Energy Production

Question 1

In the final step of the citric acid cycle,malate dehydrogenase reduces NAD⁺ to NADH.Into what product is malate converted in this reaction?

A)citrate
B)fumarate
C)oxaloacetate
D)acetyl CoA
E)ATP

Answer 1

oxaloacetate

Question 2

In which stage of metabolism is the most energy in the form of ATP produced?

A)oxidative phosphorylation
B)digestion of food molecules
C)transcription pathway
D)citric acid cycle
E)glycolysis

Answer 2

oxidative phosphorylation

Question 3

What molecule acts as a positive allosteric effector of the conversion of isocitrate to α-ketoglutarate in the citric acid cycle?

A)NADH
B)ATP
C)ADP
D)CO₂
E)O₂

Answer 3

ADP

Question 4

Which organelle in the cytoplasm of the cell is the energy-producing factory of the cell?

A)nucleus
B)ribosomes
C)mitochondria
D)lysosomes
E)endoplasmic reticulum

Question 5

A portion of the citric acid cycle is shown below.What are the identities of A and B? citrate → A → isocitrate → B

A)A = succinate; B = α-ketoglutarate
B)A = α-ketoglutarate; B = succinate
C)A = cis-aconitate; B = α-ketoglutarate
D)A = malate; B = fumarate
E)A = cis-aconitate; B = oxaloacetate

Question 6

What is the primary function of the citric acid cycle in metabolism?

A)to break down food molecules into smaller components so they can be absorbed by the blood
B)to synthesize ATP from the energy produced in the hydrolysis of citric acid
C)to provide the enzymes necessary for the hydrolysis of carbohydrates,fats,and proteins
D)to convert acetyl groups to CO₂ molecules,and provide reduced coenzymes for electron transport and synthesis of ATP
E)to join two-carbon acetyl groups in a cyclic series of reactions to form glucose,which can then be used for energy

Question 7

What is the term for the folded ridges in the inner membrane of the mitochondria?

A)endoplasmic reticulum
B)matrix
C)cristae
D)ribosomes
E)β-pleated sheets

Question 8

FADH₂ is a less powerful reducing agent (electron donor)than NADH.What is the consequence of this in oxidative phosphorylation?

A)FADH₂ requires more steps than NADH does in electron transport to become oxidized.
B)The electrons from FADH₂ enter electron transport at a higher energy level than the electrons from NADH.
C)A molecule of FADH₂ is only capable of producing 2 molecules of ATP,while a molecule of NADH is capable of producing 3 molecules of ATP.
D)Oxidation of FADH₂ occurs in the cytoplasm of the cell,while oxidation of NADH occurs in the mitochondria.
E)FADH₂ can only donate 1 phosphate group to ATP,while NADH can donate 2 phosphate groups to ATP.

Question 9

What is the source of energy for the synthesis of ATP in oxidative phosphorylation?

A)O₂
B)H⁺ flowing through ATP synthase
C)ADP
D)inorganic phosphate ions
E)hydrolysis of acetyl CoA

Question 10

Which of the following best describes the function of NAD⁺ and FAD in catabolic pathways?

A)competitive inhibitors of the enzymes present in each pathway
B)oxidizing agents that accept electrons and hydrogen ions from compounds undergoing oxidation
C)non-competitive inhibitors of the enzymes present in each pathway
D)transport molecules that carry two-carbon acetyl units to or from the different pathways
E)enzymes that catalyze breaking the phosphoanydride bond of ATP

Question 11

Which statement concerning regulation of the citric acid cycle is TRUE?

A)High levels of ATP inhibit the reactions of the cycle.
B)High levels of NADH inhibit the reactions of the cycle
C)Low levels of ATP stimulate the reactions of the cycle.
D)High levels of ADP stimulate the reactions of the cycle.
E)All of the statements are true.

Question 12

To what molecule is the acetyl group of acetyl CoA transferred in the first step of the citric acid cycle?

A)citrate
B)alanine
C)coenzyme A
D)oxaloacetate
E)ATP

Question 13

What is the role of F₀ in the F₀F₁ complex used in oxidative phosphorylation?

A)It accepts two electrons and a hydrogen ion from NADH in forming NAD⁺.
B)It accepts two electrons and two hydrogen ions from FADH₂ in forming FAD.
C)It pumps H⁺ out of the mitochondrial matrix into the intermembrane space.
D)It provides the channel for the return of H⁺ to the matrix of the mitochondria.
E)It uses the energy released from the flow of H⁺ to the matrix to synthesize ATP.

Question 14

In what way is the reaction shown a key one in carbohydrate catabolism?

A)The reaction allows pyruvate to enter the citric acid cycle where it can be completely oxidized to CO₂.
B)The reaction represents the final step in aerobic respiration.
C)The reaction is the only NADH producing reaction in the citric acid cycle.
D)The reaction is the only decarboxylation reaction in the citric acid cycle.
E)The reaction represents the only energy-producing reaction of the citric acid cycle.

Question 15

What is the primary function of electron transport and oxidative phosphorylation?

A)to provide electrons to break the phosphoanydride bond of ATP
B)to synthesize the reduced coenzymes NADH and FADH₂ that are necessary for digestion
C)to transport electrons and energy from ATP to ADP
D)to oxidize the reduced coenzymes NADH and FADH₂,and provide energy for the synthesis of ATP
E)to oxidize food molecules to acetyl CoA and prepare them for entry into the citric acid cycle

Question 16

Where in the mitochondrion are the protein complexes responsible for oxidative phosphorylation located?

A)cytoplasm
B)matrix
C)intermembrane space
D)inner mitochondrial membrane
E)outer mitochondrial membrane

Question 17

What cyclic metabolic pathway is the final stage of the degradation of carbohydrates,fats,and amino acids released from dietary proteins?

A)urea cycle
B)pentose phosphate pathway
C)Cori cycle
D)β-oxidation spiral
E)citric acid cycle

Question 18

What alternative name of the citric acid cycle is used in honor of the scientist who first proposed the steps of the cycle?

A)Cori cycle
B)Embden-Meyerhof pathway
C)Krebs cycle
D)Watson-Crick cycle
E)Chargaff cycle

Question 19

Which statement concerning the stages of catabolism is FALSE?

A)The primary function of digestion is to break down large food molecules into smaller ones that can be absorbed by the blood.
B)The primary function of Stage II is to produce NADH and FADH₂ for the citric acid cycle.
C)Most food molecules enter Stage III of catabolism in the form of acetyl CoA.
D)The primary function of the citric acid cycle in Stage III is to oxidize acetyl groups to CO₂,and provide reduced coenzymes for the synthesis of ATP.
E)The primary function of electron transport and oxidative phosphorylation is to oxidize NADH and FADH₂,and provide energy for the production of ATP.

Question 20

When amino acids undergo degradation in the liver,what is the first step of the process?

A)decarboxylation
B)removal of the α-amino group
C)removal of the side chain R group
D)attachment to coenzyme A
E)C-C bond cleavage

Question 21

The oxidative reactions of metabolism provide for most ATP production.In what specific part of the cell do these reactions occur?

A)nucleus
B)ribosome
C)mitochondria
D)mitochondrial membrane
E)None of the choices are correct.

Question 22

What is the term for the region of a mitochondrion that is enclosed by the inner membrane?

A)matrix space
B)intermembrane space
C)cristae
D)lumen
E)synthase space

Question 23

Step 6 in the citric acid cycle involves the dehydrogenation of succinate.What is the product of this reaction?

A)

B)

C)

D)

Question 24

How many molecules of ATP can be produced by the complete oxidation of one molecule of glucose in aerobic respiration?

A)3
B)9
C)18
D)24
E)36

Question 25

What key function does the urea cycle play in the degradation of amino acids?

A)removes ammonium ions from the blood
B)provides nitrogen for the synthesis of proteins
C)removes carbon monoxide from the blood
D)removes carboxylic acids from the blood
E)provides carboxyl groups for the synthesis of amino acids

Question 26

The enzyme fumarase catalyzes the hydration of fumarate in step 7 of the citric acid cycle.What is the product of this reaction?

A)

B)

C)

D)

E)HOCH₂CH₂OH

Question 27

The conversion of isocitrate to α-ketoglutarate in step 3 of the citric acid cycle actually occurs by the two-step process shown below.What is true about step 3a?

A)The reaction is a decarboxylation reaction.
B)The reaction is an oxidation reaction.
C)The reaction is a dehydration reaction.
D)The reaction is an alkene addition reaction.
E)The reaction is a hydrolysis reaction.

Question 28

What is the coenzyme that is required in all transamination reactions?

A)pyridoxal phosphate
B)ADP
C)coenzyme A
D)hexokinase
E)Vitamin C

Question 29

Which of the following substances serves as an intermediate through which all cellular energy sources are interconvertible?

A)acetyl CoA
B)glucose
C)ATP
D)pyruvate
E)citrate

Question 30

What is the name of the first compound formed in the citric acid cycle,produced by the transfer of an acetyl group from acetyl CoA to oxaloacetate?

A)acetone
B)citrate
C)fumarate
D)malate
E)carbon dioxide

Question 31

Which of the following structures,groups,or units does not form a part of acetyl CoA?

A)acetyl group
B)protein unit
C)β-mercaptoethylamine group
D)pantothenate unit
E)phosphorylated ADP

Question 32

What is the usual fate of the α-amino group in the catabolism of amino acids?

A)It is added to a growing peptide chain at the ribosomes.
B)It is converted into short peptide chains,which are excreted in the urine.
C)It is converted into N₂ and is expelled through the lungs.
D)It is converted into urea,which is excreted by the body in urine.
E)It is incorporated into the nucleotides of DNA and RNA.

Question 33

What type of bond in acetyl CoA links the acetyl group to the rest of the molecule?

A)ester
B)amide
C)thiol
D)thioester
E)phosphoryl

Question 34

Which of the following compounds is aconitate,the intermediate produced when the enzyme aconitase catalyzes the dehydration of citrate?

A)

B)

C)

D)

E)

Question 35

Which enzyme in the mitochondria is responsible for phosphorylation of ADP?

A)ATP
B)ATP synthase
C)ADP synthase
D)NADH
E)None of the choices are correct.

Question 36

Which correctly represents the products that result from the complete oxidation of an acetyl group in the citric acid cycle?

A)36 ATP
B)2 CO₂
C)2 CO₂,1 NADH,and 1 FADH₂
D)2 CO₂,3 NADH,1 FADH₂,and 1 ATP
E)2 acetyl CoA,1 NAD⁺,and 1 FAD

Question 37

Which of the following compounds in high concentration inhibits the pyruvate dehydrogenase complex,the enzyme responsible for the reaction shown below?

A)acetyl CoA
B)pyruvate
C)ADP
D)NAD⁺
E)FAD

Question 38

How many molecules of FADH₂ are produced by the complete oxidation of one acetyl group by the citric acid cycle?

A)1
B)2
C)4
D)6
E)12

Question 39

How many molecules of ATP are produced by oxidative phosphorylation for each molecule of NADH produced in the citric acid cycle?

A)1
B)2
C)3
D)6
E)18

Question 40

How many cycles of the citric acid cycle are required to completely oxidize all the pyruvate formed when a molecule of glucose undergoes glycolysis?

A)1
B)2
C)3
D)4
E)5

Question 41

What is the terminal electron acceptor in aerobic organisms?

A)ATP
B)NAD⁺
C)FAD
D)oxygen
E)carbon dioxide

Question 42

In addition to glutamate,what other compound is produced in the transamination reaction in which alanine and α-ketoglutarate react?

A)CH₃CH₂COO⁻
B)CO₂
C)

D)

E)

Question 43

Which of the following compounds,in high concentration,is a negative effector of citrate synthase,the enzyme that catalyzes the first step of the citric acid cycle?

A)ADP
B)acetyl CoA
C)ATP
D)NAD⁺
E)FAD

Question 44

Where in the body does the degradation of amino acids occur?

A)stomach
B)small intestine
C)liver
D)adipose tissue
E)cytoplasm

Question 45

Under what metabolic conditions is pyruvate converted to acetyl CoA?

A)sufficient O₂
B)low ATP
C)high ADP
D)low NADH
E)All of these are correct.

Question 46

When a molecule of glucose undergoes complete oxidation in the body,what percentage of its potential energy is harvested in the form of ATP molecules?

A)20%
B)40%
C)60%
D)80%
E)90%

Question 47

Which of the following substances,when present in high concentrations,inhibits the α-ketoglutarate dehydrogenase complex?

A)succinyl CoA
B)NAD⁺
C)FAD
D)P_i
E)AMP

Question 48

The enzymes for the citric acid cycle are found in what area of the mitochondria?

A)outer membrane
B)inner membrane
C)intermembrane space
D)matrix
E)All of these are correct.

Question 49

Which of the following accepts an α-amino group from amino acids in a transamination reaction?

A)glutamate
B)pyruvate
C)coenzyme A
D)acetyl CoA
E)α-ketoglutarate

Question 50

Oxaloacetate is the starting material in the first step of the citric acid cycle and the product of the last step.The last step of the citric acid cycle,the oxidation of malate,is shown below.What is the structure of the oxaloacetate product?

A)

B)

C)

D)

E)

Question 51

Which of the following statements concerning mitochondria is FALSE?

A)Mitochondria are football shaped organelles located inside the nucleus of a cell.
B)Mitochondria are believed to have evolved from bacteria that were "captured" by eukaryotic cells.
C)Mitochondria contain their own genetic information (DNA).
D)Mitochondria produce the majority of the ATP for our cells.
E)Mitochondria are self-replicating that is,they grow in size and divide to produce new mitochondria.

Question 52

Which of the following compounds is a positive effector of the allosteric enzyme isocitrate dehydrogenase?

A)ATP
B)FAD
C)GTP
D)ADP
E)NADH

Question 53

Step 7 of the citric acid cycle is shown below.Which of the following correctly describes what is occurring in this step?

A)Fumarate undergoes hydrolysis with the aid of the enzyme fumarase.
B)Fumarate undergoes reduction with the aid of the cofactor fumarase.
C)Fumarase supplies the hydrogens and electrons necessary for the hydrogenation of fumarate.
D)Fumarate undergoes hydration with the aid of the enzyme fumarase.
E)Fumarase is a coenzyme that catalyzes the hydrogenation of fumarate.

Question 54

What word is used to describe a pathway that functions in both degradative and biosynthetic reactions?

A)catabolic
B)anabolic
C)metabolic
D)amphibolic
E)diabolic

Question 55

The acetyl group is an important part of cellular metabolism.Which of the following is the acetyl group?

A)

B)

C)

D)

E)

Question 56

The first step of the urea cycle involves which of the following substances?

A)urea
B)citrulline
C)NAD⁺
D)NH₄⁺
E)P_i

Question 57

What is another name for the F₀F₁ complex involved in oxidative phosphorylation?

A)NADH
B)mitochondria
C)cristae
D)transport proteins
E)ATP synthase

Question 58

What is the ultimate fate of glucose under aerobic conditions?

A)Conversion to coenzyme A.
B)Conversion to ethanol.
C)Complete oxidation to CO₂ by way of the citric acid cycle.
D)Complete reduction to CH₄.
E)Conversion to triglycerides.

Question 59

The conversion of isocitrate to α-ketoglutarate in step 3 of the citric acid cycle actually occurs by the two-step process shown below.What is true about step 3b?

A)The reaction is a decarboxylation reaction.
B)The reaction is a hydration reaction.
C)The reaction is a dehydration reaction.
D)The reaction is an alkene addition reaction.
E)The reaction is a hydrolysis reaction.

Question 60

What protein complex in the inner mitochondrial membrane allows protons to return to the matrix?

A)cytochrome
B)electron transport carriers
C)F₀F₁
D)NADH dehydrogenase
E)porin

Question 61

Cells in fast twitch muscle fibers contain more mitochondria than do cells in slow twitch fibers.

Question 62

Which statement is true concerning aerobic versus anaerobic metabolism?

A)Aerobic metabolism is much more efficient than anaerobic metabolism.
B)Both metabolism methods produce the same amount of energy.
C)Both metabolism methods yield carbon dioxide.
D)All multicellular organisms are anaerobic.
E)In both methods of metabolism much of the energy is lost as heat.

Question 63

The outer mitochondrial membrane is porous and permeable to substances with molar masses less than 10,000 g/mol.

Question 64

The mitochondria are aerobic.

Question 65

The ribosomes found in eukaryotic cells allow the mitochondria to synthesize some of their own proteins.

Question 66

In the first stage of amino acid degradation,the carboxylate group is removed as carbon dioxide.

Question 67

The acetyl group of acetyl CoA is transferred to oxaloacetate by the enzyme citrate synthase.

Question 68

ATP synthase is a very large multi-lipid complex.

Question 69

Pyruvate is the key intermediate through which carbohydrates,amino acids,and fatty acids degrade and enter into the citric acid cycle.

Question 70

The Krebs cycle begins with an aldol condensation.

Question 71

Cyanide binds irreversibly to the heme group in cytochrome oxidase,which blocks electron transfer reactions.

Question 72

What amino acids can be used as fuel for the body?

A)No amino acids can be used as fuel.
B)All amino acids can be used as fuel.
C)Only essential amino acids can be used as fuel.
D)Only amino acids that were once part of the muscular system can be used as fuel.
E)Only those amino acids that are not needed for protein synthesis can be used as fuel.

Question 73

A deficiency of urea cycle enzymes causes an elevation of the ammonium ion concentration.

Question 74

Acetyl coenzyme A is central to cellular metabolism.

Question 75

The protein complexes responsible for oxidative phosphorylation are embedded in the inner mitochondrial membrane.