Question 1

The conversion of NAD+ to NADH is an example of reduction because

Accepted Answer

A)  the pyridine ring loses electrons (and a hydrogen) 
B)  the pyridine ring gains electrons (and a hydrogen) 
C)  the adenine ring loses electrons 
D)  the adenine ring gains electrons 
A)  the pyridine ring loses electrons (and a hydrogen) 
B)  the pyridine ring gains electrons (and a hydrogen) 
C)  the adenine ring loses electrons 
D)  the adenine ring gains electrons

Question 2

Which best describes the ΔG for hydrolysis of creatine phosphate under cellular conditions in which the concentration of creatine phosphate, creatine, and phosphate all equal 1 mM at 25°C. The ΔG° for the hydrolysis of creatine phosphate at 25°C is −43 kJ/mol.

Accepted Answer

A)  ΔG  0 kJ/mol 
A)  ΔG  0 kJ/mol

Question 3

In general, catabolism

Accepted Answer

A)  is an oxidative process that releases energy 
B)  is a reductive process that releases energy 
C)  is an oxidative process that requires energy 
D)  is a reductive process that requires energy 
E)  none of these 
A)  is an oxidative process that releases energy 
B)  is a reductive process that releases energy 
C)  is an oxidative process that requires energy 
D)  is a reductive process that requires energy 
E)  none of these

Question 4

The body allows energy consuming reactions to occur by coupling them with reactions which have a negative ΔG.

Accepted Answer

A) True 
 B)False

Question 5

In the coenzyme FAD the site to which electrons are transferred is

Accepted Answer

A)  the ribose moiety of the molecule 
B)  a purine ring system 
C)  a pyrimidine ring system 
D)  a nitrogen-containing ring system 
A)  the ribose moiety of the molecule 
B)  a purine ring system 
C)  a pyrimidine ring system 
D)  a nitrogen-containing ring system

Question 6

Which of the following is not a mechanism used to activate substrates for further metabolism?

Accepted Answer

A)  Addition of a phosphate group. 
B)  Combination with a vitamin, such as coenzyme A. 
C)  Hydrolyzing a polymer into its component monomers. 
D)  Addition of a phosphate group or combining with a vitamin. 
E)  All of these processes activate substrates. 
A)  Addition of a phosphate group. 
B)  Combination with a vitamin, such as coenzyme A. 
C)  Hydrolyzing a polymer into its component monomers. 
D)  Addition of a phosphate group or combining with a vitamin. 
E)  All of these processes activate substrates.

Question 7

By definition, a spontaneous reaction is one in which

Accepted Answer

A)  energy is released. 
B)  energy is absorbed. 
C)  the energy change is zero. 
D)  the reaction happens quickly 
E)  energy is released and the reaction happens quickly 
A)  energy is released. 
B)  energy is absorbed. 
C)  the energy change is zero. 
D)  the reaction happens quickly 
E)  energy is released and the reaction happens quickly

Question 8

When we say that the efficiency of glycolysis is about 33% we mean that

Accepted Answer

A)  2 ATP are produced and 6 ATP are involved in the overall process 
B)  2 ATP are produced in the oxidation of glucose, which contains six carbon atoms 
C)  the energy used to phosphorylate 2 ATP is 33% of the energy released in the process 
D)  all of these 
A)  2 ATP are produced and 6 ATP are involved in the overall process 
B)  2 ATP are produced in the oxidation of glucose, which contains six carbon atoms 
C)  the energy used to phosphorylate 2 ATP is 33% of the energy released in the process 
D)  all of these

Question 9

In order to drive the synthesis of ATP, the hydrolysis of an organic phosphate

Accepted Answer

A)  must have a higher free energy change. 
B)  must have a lower free energy change. 
C)  must have a free energy change equal to that of ATP. 
A)  must have a higher free energy change. 
B)  must have a lower free energy change. 
C)  must have a free energy change equal to that of ATP.

Question 10

A biological reaction with a significantly postive ΔG under cellular conditions may proceed in the forward direction because

Accepted Answer

A)  The cell will change the concentrations of the substrates and products so that the reaction can occur 
B)  The cell will raise the temperature, thereby affecting the overall thermodynamics of the reaction 
C)  the reaction can be coupled to a reaction with a more significant negative ΔG 
D)  reactions with positive ΔG values always proceed in the forward direction 
E)  None of these 
A)  The cell will change the concentrations of the substrates and products so that the reaction can occur 
B)  The cell will raise the temperature, thereby affecting the overall thermodynamics of the reaction 
C)  the reaction can be coupled to a reaction with a more significant negative ΔG 
D)  reactions with positive ΔG values always proceed in the forward direction 
E)  None of these

Question 11

An organism that is at equilibrium would be

Accepted Answer

A)  in a steady state 
B)  an open system 
C)  dead 
D)  energetically balanced 
A)  in a steady state 
B)  an open system 
C)  dead 
D)  energetically balanced

Question 12

I am performing a reaction, A → B, with ΔG°' = −0.3 kJ/mol. I start the reaction with 10 mM A and no B. After allowing the reaction to proceed for 24 hrs at room temperature and atmospheric pressure, I analyze a sample of the reaction mix to find I now have 1 mM A and 9 mM B. Which of the following conclusions should I make?

Accepted Answer

A)  The reaction has reached equilibrium. 
B)  I should come back again later; equilibrium has not yet been reached. 
C)  The formation of B from A is thermodynamically unfavorable, so I should find another starting material to make B. 
D)  I must've screwed up; there's no way I could get that result with that ΔG°' 
A)  The reaction has reached equilibrium. 
B)  I should come back again later; equilibrium has not yet been reached. 
C)  The formation of B from A is thermodynamically unfavorable, so I should find another starting material to make B. 
D)  I must've screwed up; there's no way I could get that result with that ΔG°'

Question 13

If the reaction A → B has ΔG = +25 Joule/mol and the reaction B → C has ΔG = −15 Joule/mol, the overall energy change A → C will be

Accepted Answer

A)  −40 Joule/mol. 
B)  −15 Joule/mol. 
C)  +10 Joule/mol. 
D)  +40 Joule/mol. 
E)  You cannot determine the overall reaction from the given data. 
A)  −40 Joule/mol. 
B)  −15 Joule/mol. 
C)  +10 Joule/mol. 
D)  +40 Joule/mol. 
E)  You cannot determine the overall reaction from the given data.

Question 14

Exhibit 15A Consider the reaction of alcohol dehydrogenase.
  
-Refer to Exhibit 15A. Which is the oxidizing agent?

Accepted Answer

A)  Ethanol 
B)  NAD+ 
C)  Acetaldehyde 
D)  NADH 
E)  H+ 
A)  Ethanol 
B)  NAD+ 
C)  Acetaldehyde 
D)  NADH 
E)  H+

Question 15

Spontaneous reaction always occurs at a relatively fast rate.

Accepted Answer

A) True 
 B)False

Question 16

The standard state usually used in biochemistry (ΔG°') includes

Accepted Answer

A)  all concentrations at 1 M. 
B)  all concentrations at 1 M, except for [H+], which is 10−7 M. 
C)  same as a), but at 25° C. 
D)  same as b), but at 25° C. 
E)  None of the answers 
A)  all concentrations at 1 M. 
B)  all concentrations at 1 M, except for [H+], which is 10−7 M. 
C)  same as a), but at 25° C. 
D)  same as b), but at 25° C. 
E)  None of the answers

Question 17

In order to initiate many metabolic pathways it is necessary to activate the starting materials.

Accepted Answer

A) True 
 B)False

Question 18

The production of larger molecules from smaller ones is called

Accepted Answer

A)  metabolism. 
B)  catabolism. 
C)  anabolism. 
D)  none of these 
A)  metabolism. 
B)  catabolism. 
C)  anabolism. 
D)  none of these

Question 19

Which of the following statements concerning the free energy change (ΔG) is false?

Accepted Answer

A)  The energy change for a reaction depends only on the initial and final states, and is independent of the path taken. 
B)  The overall energy change for a reaction could be calculated by summing the energy changes for a series of separate reactions that could convert the reactants to the products. 
C)  The rate of a reaction can be determined from the energy change. 
D)  The energy change is a function of the concentrations of the products and reactants at start. 
E)  All of the answers are true 
A)  The energy change for a reaction depends only on the initial and final states, and is independent of the path taken. 
B)  The overall energy change for a reaction could be calculated by summing the energy changes for a series of separate reactions that could convert the reactants to the products. 
C)  The rate of a reaction can be determined from the energy change. 
D)  The energy change is a function of the concentrations of the products and reactants at start. 
E)  All of the answers are true

Question 20

Which of the following is not true?

Accepted Answer

A)  Molecular oxygen is always a substrate in oxidation reactions. 
B)  Oxidation reactions involve the movement of electrons from one molecule to another 
C)  When a molecule is oxidized, it loses electrons 
D)  Reduction involves the gain of electrons 
A)  Molecular oxygen is always a substrate in oxidation reactions. 
B)  Oxidation reactions involve the movement of electrons from one molecule to another 
C)  When a molecule is oxidized, it loses electrons 
D)  Reduction involves the gain of electrons

Exam 15: The Importance of Energy Changes and Electron Transfer in Metabolism

The conversion of NAD+ to NADH is an example of reduction because

Which best describes the ΔG for hydrolysis of creatine phosphate under cellular conditions in which the concentration of creatine phosphate, creatine, and phosphate all equal 1 mM at 25°C. The ΔG° for the hydrolysis of creatine phosphate at 25°C is −43 kJ/mol.

In general, catabolism

The body allows energy consuming reactions to occur by coupling them with reactions which have a negative ΔG.

In the coenzyme FAD the site to which electrons are transferred is

Which of the following is not a mechanism used to activate substrates for further metabolism?

By definition, a spontaneous reaction is one in which

When we say that the efficiency of glycolysis is about 33% we mean that

In order to drive the synthesis of ATP, the hydrolysis of an organic phosphate

A biological reaction with a significantly postive ΔG under cellular conditions may proceed in the forward direction because

An organism that is at equilibrium would be

If the reaction A → B has ΔG = +25 Joule/mol and the reaction B → C has ΔG = −15 Joule/mol, the overall energy change A → C will be

Exhibit 15A Consider the reaction of alcohol dehydrogenase. -Refer to Exhibit 15A. Which is the oxidizing agent?

Spontaneous reaction always occurs at a relatively fast rate.

The standard state usually used in biochemistry (ΔG°') includes

In order to initiate many metabolic pathways it is necessary to activate the starting materials.

The production of larger molecules from smaller ones is called

Which of the following statements concerning the free energy change (ΔG) is false?

Which of the following is not true?

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: Biosynthesis of RNA

Protein Synthesis: Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses, Cancer, and Immunology

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism: Cellular Signaling

Filters

The conversion of NAD⁺ to NADH is an example of reduction because