Question 1

Which series best summarizes the relative energies of the different stages of an exergonic chemical reaction?

Accepted Answer

A)  Products > transition state > reactants 
B)  Reactants > transition state > products 
C)  Products > reactants > transition state 
D)  Transition state > products > reactants 
E)  Transition state > reactants > products 
A)  Products > transition state > reactants 
B)  Reactants > transition state > products 
C)  Products > reactants > transition state 
D)  Transition state > products > reactants 
E)  Transition state > reactants > products

Question 2

Refer to the graph below.   The graph shows data collected using a purified sample of the enzyme phosphofructokinase (PFK).This enzyme catalyzes the reaction between fructose 6-phosphate and ATP to form fructose 1,6-bisphosphate.Which statement is consistent with the data shown in the graph?

Accepted Answer

A)  PFK is allosterically inhibited by ATP. 
B)  PFK is allosterically activated by ATP. 
C)  ATP is a competitive inhibitor of PFK. 
D)  ATP functions as a substrate and not as an inhibitor of PFK. 
E)  ATP functions as a substrate and not as an activator of PFK. 
A)  PFK is allosterically inhibited by ATP. 
B)  PFK is allosterically activated by ATP. 
C)  ATP is a competitive inhibitor of PFK. 
D)  ATP functions as a substrate and not as an inhibitor of PFK. 
E)  ATP functions as a substrate and not as an activator of PFK.

Question 3

Refer to the figure below.   Which word best fits into this figure where the question mark is located?

Accepted Answer

A)  Catalysis 
B)  Equilibrium 
C)  Energy 
D)  Metabolism 
E)  Entropy 
A)  Catalysis 
B)  Equilibrium 
C)  Energy 
D)  Metabolism 
E)  Entropy

Question 4

Which effector of enzyme activity is least likely to be utilized by cells?

Accepted Answer

A)  Allosteric inhibitors 
B)  Allosteric activators 
C)  Competitive inhibitors 
D)  Noncompetitive inhibitors 
E)  Irreversible inhibitors 
A)  Allosteric inhibitors 
B)  Allosteric activators 
C)  Competitive inhibitors 
D)  Noncompetitive inhibitors 
E)  Irreversible inhibitors

Question 5

When ATP is hydrolyzed, the reaction produces all of the following except

Accepted Answer

A)  AMP. 
B)  ADP. 
C)  phosphate ions. 
D)  pyrophosphate ions. 
E)  water. 
A)  AMP. 
B)  ADP. 
C)  phosphate ions. 
D)  pyrophosphate ions. 
E)  water.

Question 6

The greater the affinity of an enzyme for its substrate, the _______ the substrate dissociation constant (KD).

Accepted Answer

Question 7

The standard free energy change for the hydrolysis of GTP (guanosine triphosphate) to GDP + Pi is -7.3 kcal/mol, similar to that for ATP.From this information, one can conclude that the

Accepted Answer

A)  reaction will never reach equilibrium. 
B)  free energy of GDP and phosphate is higher than the free energy of GTP. 
C)  reaction requires energy. 
D)  reaction is endergonic. 
E)  reaction is exergonic. 
A)  reaction will never reach equilibrium. 
B)  free energy of GDP and phosphate is higher than the free energy of GTP. 
C)  reaction requires energy. 
D)  reaction is endergonic. 
E)  reaction is exergonic.

Question 8

The inhibition of enzyme activity by noncompetitive inhibitors can be reduced

Accepted Answer

A)  by decreasing the concentration of allosteric enzymes. 
B)  by decreasing the concentration of substrate. 
C)  by increasing the concentration of competitive inhibitor. 
D)  by increasing the concentration of substrate. 
E)  only when they become unbound. 
A)  by decreasing the concentration of allosteric enzymes. 
B)  by decreasing the concentration of substrate. 
C)  by increasing the concentration of competitive inhibitor. 
D)  by increasing the concentration of substrate. 
E)  only when they become unbound.

Question 9

In a chemical reaction, transition-state intermediates have free energies that are

Accepted Answer

A)  lower than those of either the reactants or the products. 
B)  lower than those of the reactants, but higher than those of the products. 
C)  higher than those of either the reactants or the products. 
D)  higher than those of the reactants, but lower than those of the products. 
E)  lower than those of the reactants, but the same as those of the products. 
A)  lower than those of either the reactants or the products. 
B)  lower than those of the reactants, but higher than those of the products. 
C)  higher than those of either the reactants or the products. 
D)  higher than those of the reactants, but lower than those of the products. 
E)  lower than those of the reactants, but the same as those of the products.

Question 10

The F1F1F1S1F1F1F10G of a reaction tells us all of the following except

Accepted Answer

A)  the rate of the reaction. 
B)  the direction of the reaction. 
C)  whether the reaction is exergonic or endergonic. 
D)  whether the reaction requires or releases energy. 
E)  whether a higher free energy is in the product or in the reactants. 
A)  the rate of the reaction. 
B)  the direction of the reaction. 
C)  whether the reaction is exergonic or endergonic. 
D)  whether the reaction requires or releases energy. 
E)  whether a higher free energy is in the product or in the reactants.

Question 11

A noncompetitive inhibitor hinders binding of a substrate to an enzyme by

Accepted Answer

A)  binding to the substrate. 
B)  binding to the active site. 
C)  lowering the activation energy. 
D)  increasing the F1F1F1S1F1F1F10G of the reaction. 
E)  changing the shape of the active site. 
A)  binding to the substrate. 
B)  binding to the active site. 
C)  lowering the activation energy. 
D)  increasing the F1F1F1S1F1F1F10G of the reaction. 
E)  changing the shape of the active site.

Question 12

Refer to the figure below.   The figure shows a branched metabolic pathway involving metabolites indicated with letters.The enzymes catalyzing the steps in this pathway are indicated with numbers.What type of data would be expected, based on the pathway shown?

Accepted Answer

A)  Enzyme 10 is allosterically activated by metabolite E. 
B)  Enzyme 3 is allosterically inhibited by metabolite G. 
C)  Enzyme 7 is allosterically inhibited by metabolite K. 
D)  Metabolite D functions as a competitive inhibitor of enzyme 1. 
E)  Metabolite G functions as a competitive inhibitor of enzyme 4. 
A)  Enzyme 10 is allosterically activated by metabolite E. 
B)  Enzyme 3 is allosterically inhibited by metabolite G. 
C)  Enzyme 7 is allosterically inhibited by metabolite K. 
D)  Metabolite D functions as a competitive inhibitor of enzyme 1. 
E)  Metabolite G functions as a competitive inhibitor of enzyme 4.

Question 13

In glycolysis, the exergonic reaction 1,3-diphosphoglycerate F1F1F1S1F1F1F10 3-phosphoglycerate is coupled to the reaction ADP + PiF1F1F1S1F1F1F10 ATP.Based on this information, which statement is most likely to be true about the reaction ADP + PiF1F1F1S1F1F1F10 ATP?

Accepted Answer

A)  The reaction never reaches equilibrium. 
B)  The reaction is spontaneous. 
C)  There is a large decrease in free energy. 
D)  The reaction is endergonic. 
E)  Temperature will not affect the rate constant of the reaction. 
A)  The reaction never reaches equilibrium. 
B)  The reaction is spontaneous. 
C)  There is a large decrease in free energy. 
D)  The reaction is endergonic. 
E)  Temperature will not affect the rate constant of the reaction.

Question 14

The hydrolysis of sucrose to glucose and fructose is exergonic.However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose.Why?

Accepted Answer

A)  The change in free energy of the reaction is positive. 
B)  The activation energy of the reaction is high. 
C)  The change in free energy of the reaction is negative. 
D)  This is a hydrolysis reaction, so it requires an input of energy. 
E)  The free energy of the products is higher than the free energy of the reactants. 
A)  The change in free energy of the reaction is positive. 
B)  The activation energy of the reaction is high. 
C)  The change in free energy of the reaction is negative. 
D)  This is a hydrolysis reaction, so it requires an input of energy. 
E)  The free energy of the products is higher than the free energy of the reactants.

Question 15

The enzyme lysozyme causes strain in its substrate as part of its catalytic mechanism.The enzyme UDP-glucose dehydrogenase forms a covalent intermediate with its substrate as part of its catalytic mechanism.This intermediate breaks down to form products, regenerating the enzyme in its original form.Lysozyme differs from UDP-glucose dehydrogenase in that it does not itself undergo _______ change as part of its catalytic mechanism.

Accepted Answer

The answer of The enzyme lysozyme causes strain in its...

Question 16

The molecules that are acted on by an enzyme are called

Accepted Answer

A)  products. 
B)  substrates. 
C)  carriers. 
D)  prosthetics. 
E)  effectors. 
A)  products. 
B)  substrates. 
C)  carriers. 
D)  prosthetics. 
E)  effectors.

Question 17

Which statement about enzymes is false?

Accepted Answer

A)  Enzymes do not affect the equilibrium point of a reaction. 
B)  Enzymes lower activation energy. 
C)  Enzymes are highly specific. 
D)  Enzymes can convert an endergonic to an exergonic reaction. 
E)  Enzymes undergo no net chemical change during catalysis. 
A)  Enzymes do not affect the equilibrium point of a reaction. 
B)  Enzymes lower activation energy. 
C)  Enzymes are highly specific. 
D)  Enzymes can convert an endergonic to an exergonic reaction. 
E)  Enzymes undergo no net chemical change during catalysis.

Question 18

A plant makes sugars via photosynthesis and is consumed by an herbivore.The herbivore in turn breaks down the sugars, producing energy it then uses to build a nest.Which sequence represents the energy transformation of this pathway?

Accepted Answer

A)  Light F1F1F1S1F1F1F10 chemical F1F1F1S1F1F1F10 mechanical 
B)  Chemical F1F1F1S1F1F1F10 kinetic F1F1F1S1F1F1F10 heat 
C)  Heat F1F1F1S1F1F1F10 chemical F1F1F1S1F1F1F10 potential 
D)  Light F1F1F1S1F1F1F10 kinetic F1F1F1S1F1F1F10 chemical 
E)  Mechanical F1F1F1S1F1F1F10 heat F1F1F1S1F1F1F10 potential 
A)  Light F1F1F1S1F1F1F10 chemical F1F1F1S1F1F1F10 mechanical 
B)  Chemical F1F1F1S1F1F1F10 kinetic F1F1F1S1F1F1F10 heat 
C)  Heat F1F1F1S1F1F1F10 chemical F1F1F1S1F1F1F10 potential 
D)  Light F1F1F1S1F1F1F10 kinetic F1F1F1S1F1F1F10 chemical 
E)  Mechanical F1F1F1S1F1F1F10 heat F1F1F1S1F1F1F10 potential

Question 19

A theoretical enzyme, anyase, catalyzes the same reaction using five different substrates.The dissociation constants for these substrates and the enzyme are listed below.Which substrate will produce the greatest concentration of anyase-substrate complex?

Accepted Answer

A)  Substrate A, KD = 10-7 M 
B)  Substrate B, KD = 10-4 M 
C)  Substrate C, KD = 100 M 
D)  Substrate D, KD = 104 M 
E)  Substrate E, KD = 107 M 
A)  Substrate A, KD = 10-7 M 
B)  Substrate B, KD = 10-4 M 
C)  Substrate C, KD = 100 M 
D)  Substrate D, KD = 104 M 
E)  Substrate E, KD = 107 M

Question 20

If the temperature of an enzyme-catalyzed reaction is increased from 20°C to 70°C, the rate of the reaction

Accepted Answer

A)  will increase indefinitely. 
B)  will decrease immediately. 
C)  will decrease to zero because the enzyme will become denatured. 
D)  will decrease and then increase. 
E)  cannot be determined without information regarding optimal temperature. 
A)  will increase indefinitely. 
B)  will decrease immediately. 
C)  will decrease to zero because the enzyme will become denatured. 
D)  will decrease and then increase. 
E)  cannot be determined without information regarding optimal temperature.

Exam 8: Energy, Enzymes, and Metabolism

Which series best summarizes the relative energies of the different stages of an exergonic chemical reaction?

Refer to the graph below. The graph shows data collected using a purified sample of the enzyme phosphofructokinase (PFK).This enzyme catalyzes the reaction between fructose 6-phosphate and ATP to form fructose 1,6-bisphosphate.Which statement is consistent with the data shown in the graph?

Refer to the figure below. Which word best fits into this figure where the question mark is located?

Which effector of enzyme activity is least likely to be utilized by cells?

When ATP is hydrolyzed, the reaction produces all of the following except

The greater the affinity of an enzyme for its substrate, the _______ the substrate dissociation constant (KD).

The standard free energy change for the hydrolysis of GTP (guanosine triphosphate) to GDP + Pi is -7.3 kcal/mol, similar to that for ATP.From this information, one can conclude that the

The inhibition of enzyme activity by noncompetitive inhibitors can be reduced

In a chemical reaction, transition-state intermediates have free energies that are

The G of a reaction tells us all of the following except

A noncompetitive inhibitor hinders binding of a substrate to an enzyme by

Refer to the figure below. The figure shows a branched metabolic pathway involving metabolites indicated with letters.The enzymes catalyzing the steps in this pathway are indicated with numbers.What type of data would be expected, based on the pathway shown?

In glycolysis, the exergonic reaction 1,3-diphosphoglycerate  3-phosphoglycerate is coupled to the reaction ADP + Pi ATP.Based on this information, which statement is most likely to be true about the reaction ADP + Pi ATP?

The hydrolysis of sucrose to glucose and fructose is exergonic.However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose.Why?

The molecules that are acted on by an enzyme are called

Which statement about enzymes is false?

A plant makes sugars via photosynthesis and is consumed by an herbivore.The herbivore in turn breaks down the sugars, producing energy it then uses to build a nest.Which sequence represents the energy transformation of this pathway?

A theoretical enzyme, anyase, catalyzes the same reaction using five different substrates.The dissociation constants for these substrates and the enzyme are listed below.Which substrate will produce the greatest concentration of anyase-substrate complex?

If the temperature of an enzyme-catalyzed reaction is increased from 20°C to 70°C, the rate of the reaction

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The greater the affinity of an enzyme for its substrate, the _______ the substrate dissociation constant (K_D).

The standard free energy change for the hydrolysis of GTP (guanosine triphosphate) to GDP + P_i is -7.3 kcal/mol, similar to that for ATP.From this information, one can conclude that the

In glycolysis, the exergonic reaction 1,3-diphosphoglycerate  3-phosphoglycerate is coupled to the reaction ADP + P_i ATP.Based on this information, which statement is most likely to be true about the reaction ADP + P_i ATP?