Online Quiz 6

1 of 20
A competitive inhibitor of the activity of an enzyme
a. binds to an allosteric site on the enzyme.
b. permanently inhibits the activity of the enzyme.
c. binds to the active site of the enzyme.
d. is a feedback inhibitor.
e. binds to the same extent at all substrate concentrations.
1 out of 1 Correct. Textbook Reference: 6.5 How Are Enzyme Activities Regulated? pp. 131–133

2 of 20
An allosteric enzyme
a. usually contains a single polypeptide chain.
b. may show a sigmoid dependence on substrate concentration.
c. is not subject to regulation of its activity.
d. often catalyzes a reaction near the end of a pathway.
e. is normally subject to irreversible inhibition.
1 out of 1 Correct. Textbook Reference: 6.5 How Are Enzyme Activities Regulated? pp. 132–133

3 of 20
A competitive inhibitor of an enzyme-catalyzed reaction
a. Always interferes with product release.
b. Inhibits to the same extent at all substrate concentrations.
c. cannot bind to the active site.
d. binds to an allosteric site.
e. is usually structurally similar to the substrate.
1 out of 1 Correct. Textbook Reference: 6.5 How Are Enzyme Activities Regulated? pp. 131–132

4 of 20
Which of the following statements is (are) inconsistent with the first and second laws of thermodynamics?
a. Living organisms can produce energy.
b. Chemical energy may be converted to light energy.
c. The total energy of a system is available to do work.
d. Potential energy may be used to do work.
e. Both a and c
1 out of 1 Correct. Textbook Reference: 6.1 What Physical Principles Underlie Biological Energy Transformations? pp. 119–121

5 of 20
A prosthetic group of an enzyme
a. readily dissociates from the enzyme.
b. is an organic molecule made up of amino acids.
c. participates in the reaction catalyzed by the enzyme.
d. is unchanged during the reaction catalyzed by the enzyme.
e. is made up of cofactors.
1 out of 1 Correct. Textbook Reference: 6.5 How Are Enzyme Activities Regulated? p. 130

6 of 20
If ΔG for a reaction is positive, the reaction
a. is spontaneous.
b. could drive an energy-requiring process.
c. is endergonic.
d. would necessarily have a positive ΔH.
e. would proceed quickly.
1 out of 1 Correct. Textbook Reference: 6.1 What Physical Properties Underlie Biological Energy Transformations? p. 121

7 of 20
In a reaction catalyzed by an enzyme,
a. the enzyme's structure is permanently modified.
b. the rate of the reaction is linearly dependent on the substrate concentration.
c. the enzyme does not affect the equilibrium constant for the reaction
d. substrate binding is nonspecific.
e. the rate of the reaction would be unaffected by temperature.
1 out of 1 Correct. Textbook Reference: 6.4 How Do Enzymes Work? pp. 126–128

8 of 20
Why is the statement, “ATP produces energy for life,” wrong?
a. It requires energy to make ATP.
b. It is a violation of the second law of thermodynamics.
c. It is a violation of the first law of kinetics.
d. It is a violation of the first law of thermodynamics.
e. Life produces ATP.
1 out of 1 Correct. Textbook Reference: 6.1 What Physical Principles Underlie Biological Energy Transformation? p. 119

9 of 20
The binding of a substrate to an enzyme
a. is covalent.
b. is irreversible.
c. is nonspecific.
d. may involve hydrogen bonds and van der Waal interactions.
e. does not induce shape changes in the enzyme.
1 out of 1 Correct. Textbook Reference: 6.4 How Do Enzymes Work? p. 129

10 of 20
An enzyme could increase the rate of a reaction by
a. orienting substrates.
b. inducing strain on the substrate.
c. reacting chemically with the substrate.
d. donating a proton to the substrate.
e. All of the above
1 out of 1 Correct. Textbook Reference: 6.4 How Do Enzynes Work? p. 128

11 of 20
Suppose the reaction A↔B has a large, negative ΔG. In what direction, how far and how fast will the reaction proceed?
a. From A to B; at equilibrium mostly B would be present; insufficient information is given to predict the rate of the reaction
b. From B to A; at equilibrium mostly A would be present; the reaction would be slow
c. From A to B; at equilibrium mostly B would be present; the reaction would be fast
d. From the information given the direction and how far the reaction would proceed cannot be determined, but the rate of the reaction would be fast
e. From A to B; at equilibrium mostly B would be present; the reaction would be slow
1 out of 1 Correct. Textbook Reference: 6.2 What is the Role of ATP in Biochemical Energetics? p. 123

12 of 20
A reaction that has a negative ΔG
a. is endergonic.
b. necessarily proceeds more rapidly than a reaction with a less negative ΔG.
c. is spontaneous.
d. cannot be used to drive a reaction with a positive ΔG.
e. None of the above
1 out of 1 Correct. Textbook Reference: 6.1 What Physical Principles Underlie Biological Energy Transformations? pp. 121–122

13 of 20
The activity of enzymes may be affected by
a. allosteric inhibitors.
b. allosteric activators.
c. competitive inhibitors
d. non-competitive inhibitors.
e. All of the above
1 out of 1 Correct. Textbook Reference: 6.5 How Are Enzyme Activities Regulated? p. 133

14 of 20
Which of the following parameters determines how far and in what direction a reaction will proceed?
a. The activation energy
b. ΔG
c. ΔH
d. ΔS
e. T, the absolute temperature
1 out of 1 Correct. Textbook Reference: 6.3 What Are Enzymes? pp. 126–127

15 of 20
Anabolic pathways are usually _, whereas catabolic pathways are usually _. Anabolic pathways are associated with ___ in entropy.
a. endergonic; exergonic; an increase
b. endergonic; exergonic; a decrease
c. exergonic; endergonic; no change
d. exergonic; endergonic; an increase
e. endergonic; exergonic; no change
1 out of 1 Correct. Textbook Reference: 6.2 What is the Role of ATP in Biochemical Energetics? p. 122

16 of 20
Entropy
a. is the total energy in a system.
b. tends to decrease in the universe.
c. when multiplied times the absolute temperature, is the useable energy in a system.
d. is related to the disorder or randomness of a system.
e. is represented in equations by the letter "H".
1 out of 1 Correct. Textbook Reference: 6.1 What Physical Principles Underlie Biological Energy Transformations? p. 120

17 of 20
The rate of a reaction catalyzed by an enzyme
a. is independent of the substrate concentration.
b. may be increased or decreased by temperature.
c. is always accelerated by increasing the pH.
d. may be inhibited by allosteric effectors.
e. Both b and d
1 out of 1 Correct. Textbook Reference: 6.4 How Do Enzymes Work? and 6.5 How Are Enzyme Activities Regulated? pp. 130–133

18 of 20
Enzymes
a. may be subject to feedback inhibition.
b. change the value of ΔG for a reaction.
c. always require cofactors.
d. have no effect on the activation energy barrier of a reaction.
e. are permanently changed by the reactions they facilitate.
1 out of 1 Correct. Textbook Reference: 6.3 What Are Enzymes? pp.125–127

19 of 20
To be metabolized, glucose must be converted to glucose 6-phosphate. However, at equilibrium, a mixture of glucose and phosphate at concentrations that exist in cells would contain little glucose 6-phosphate. How do cells circumvent this problem?
a. An enzyme lowers the activation energy barrier to favor glucose 6-phosphate formation.
b. An enzyme changes the equilibrium constant for the reaction to favor glucose 6-phosphate formation.
c. ATP, rather than phosphate, is used as the donor of the phosphoryl group and the formation of glucose 6-phosphate is endergonic.
d. ATP is used as the donor of the phosphoryl group and the formation of glucose 6-phosphate is exergonic.
e. Phosphate from the hydrolysis of ATP is used to phosphorylate glucose.
1 out of 1 Correct. Textbook Reference: 6.2 What is the Role of ATP in Biochemical Energetics? pp. 124–125

20 of 20
Which of the following statements about ATP is false?
a. The synthesis of ATP is an endergonic reaction.
b. The hydrolysis of ATP to ADP and Pi is an exergonic reaction.
c. The phosphate bond energy of ATP is used to power catabolic metabolism.
d. ATP is a building block of RNA
e. The phosphate bond energy of ATP may be transformed into light.
1 out of 1 Correct. Textbook Reference: 6.2 What is the Role of ATP in Biochemical Energetics? pp. 124–125

thanks

Way to be on top of things!

Gracias Amigos

Thank you, but make sure we don't just copy…. We gotta read, too

Looks like they are all correct!

Thank you

You are right, it is important that we read too because not everything is covered in the quiz!

Yes, reading is very important but i try and do the quizes enough so i know the info before i get the 100 on it. I usually take it before i read the chapter when i get done with chapter and then get a 100 before its due :)

This will be great study material. Thank you!

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