Question 1

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

Accepted Answer

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 
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 2

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

Accepted Answer

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 
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 3

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

Accepted Answer

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. 
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 4

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

Accepted Answer

A) True 
 B)False

Question 5

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

Accepted Answer

A) True 
 B)False

Question 6

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

Accepted Answer

A) True 
 B)False

Question 7

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

Accepted Answer

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

Question 8

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

Accepted Answer

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

Question 9

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

Accepted Answer

A) True 
 B)False

Question 10

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

Accepted Answer

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

Question 11

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

Accepted Answer

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

Question 12

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

Accepted Answer

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

Question 13

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

Accepted Answer

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 
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 14

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

Accepted Answer

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 
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 15

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

Accepted Answer

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

Question 16

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

Accepted Answer

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. 
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 17

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

Accepted Answer

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

Question 18

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

Accepted Answer

A) True 
 B)False

Question 19

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?

Accepted Answer

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

Question 20

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

Accepted Answer

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

Exam 22: Aerobic Respiration and Energy Production

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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?

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

Chemistry - Methods and Measurement

The Structure of the Atom and the Periodic Table

Structure and Properties of Ionic and Covalent Compounds

Calculations, chemical Changes, and the Chemical Equation

States of Matter: Gases, liquids, and Solids

Solutions

Energy,rate and Equilibrium

Acids and Bases

The Nucleus, radioactivity, and Nuclear Medicine

An Introduction to Organic Chemistry

The Unsaturated Hydrocarbons: Alkenes, alkynes, and Aromatics

Alcohols, phenols, thiols, and Ethers

Aldehydes and Ketones

Carboxylic Acids and Carboxylic Acid Derivatives

Amines and Amides

Carbohydrates

Lipids and Their Functions in Biochemical Systems

Protein Structure and Function

Enzymes

Introduction to Molecular Genetics

Carbohydrate Metabolism

Fatty Acid Metabolism

Filters

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

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

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