Question 1

Substances the bind to an enzyme and increase its activity are called

Accepted Answer

A)  negative regulators.
B)  positive regulators.
C)  allosteric regulators.
D)  neutral regulators.

Question 2

A form of inhibition that occurs by covalent modification is the

Accepted Answer

A)  phosphorylation of an active site by ATP.
B)  dephosphorylation of an active site by hydrolysis.
C)  transfer of a phosphate group to ADP.
D)  all of these

Question 3

In order to have full activity,some enzymes require certain metal ions,such as Mg2+ or Zn2+.This component is called a

Accepted Answer

A)  cofactor.
B)  coenzyme.
C)  regulator.
D)  substrate.
E)  inhibitor.

Question 4

A model that explains how the substrate fits exactly into the active site of an enzyme is called

Accepted Answer

A)  a coenzyme.
B)  an induced-fit.
C)  a lock-and-key.
D)  substrate specific.
E)  an active site.

Question 5

A deficiency in in which of the following has been shown to cause goiter?

Accepted Answer

A)  magnesium
B)  iodine
C)  selenium
D)  chlorine
E)  chromium

Question 6

Noncompetitive inhibition can be overcome by

Accepted Answer

A)  increasing the concentration of substrate.
B)  increasing the concentration of enzyme.
C)  decreasing the concentration of inhibitor.
D)  decreasing the concentration of products.
E)  decreasing the concentration of substrate.

Question 7

When a molecule other than the correct substrate interacts with some part of an enzyme to alter the shape of the active site,the process is called

Accepted Answer

A)  competitive inhibition.
B)  noncompetitive inhibition.
C)  irreversible inhibition.
D)  activation.
E)  covalent modification.

Question 8

Enzymes have an optimum temperature for their catalytic activity.This is best explained by the balance between the ________ number of collisions and the ________ rate of denaturation of the enzyme as temperatures increase.

Accepted Answer

A)  increased;increased
B)  decreased;increased
C)  increased;decreased
D)  decreased;decreased
E)  none of the above

Question 9

Some enzymes are produced as zymogens because

Accepted Answer

A)  the reactions they catalyze are undesirable at the site of production.
B)  they must have both an active site and an allosteric site,and these can't be produced simultaneously.
C)  the actual enzyme molecules are so large that they must be produced in pieces and assembled as needed.
D)  the pH at the site of production is very different from the pH at the site where they are used.
E)  none of these

Question 10

Which of the following vitamins has antioxidant properties?

Accepted Answer

A)  vitamin C
B)  vitamin E
C)  vitamin K
D)  vitamin B
E)  vitamins C and E

Question 11

Match the following.
-induced-fit model

Accepted Answer

A)  a type of enzyme that catalyzes the breakdown of large molecules by reaction with water
B)  a type of enzyme that catalyzes the transfer of a functional group from one molecule to another
C)  a substance that prevents harmful reactions of free radicals
D)  an inactive form of an enzyme;also called a proenzyme
E)  any process which decreases the rate of an enzyme catalyzed reactionF) a type of enzyme that catalyzes the joining of two molecules togetherG) a description of the catalytic activity of an enzyme,where a small value means that very few molecules are acted on in a unit of timeH) a description of enzyme activity based on the ability of the enzyme to change shape in order to accommodate substrate moleculesI) any process that increases the rate of an enzyme catalyzed reactionJ) a type of enzyme that catalyzes the removal of a small molecule from a larger oneK) a description of enzyme activity based on an exact match between the shapes of the active site and the substrate moleculeL) a small organic molecule necessary for good health that must be obtained in the dietM) a type of enzyme that catalyzes the internal rearrangement of moleculesN) a type of enzyme that catalyzes oxidation or reduction reactions

Question 12

An enzyme functions best at its optimal temperature.What would possibly happen if the temperature is increased greatly?

Accepted Answer

A)  The enzyme would become denatured.
B)  The reaction rate would increase.
C)  The reaction would slow down.
D)  There would be no effect on the enzyme's activity.

Question 13

One of the enzymes involved in glycolysis is phosphofructokinase.What type of biochemical reaction is it catalyzing?

Accepted Answer

A)  Transfer of a carbonyl group from glucose to fructose.
B)  Removal of a phosphate group from fructose-6-phosphate.
C)  Transfer of a phosphate group from ATP to fructose-6-phosphate.
D)  Transfer of a phosphate group from fructose-1,6-bisphosphate to fructose.
E)  none of the above

Question 14

Enzymes that are affected by the binding of an inhibitor are called

Accepted Answer

A)  induced enzymes.
B)  allosteric enzymes.
C)  proenzymes.
D)  zymogens.
E)  controlled enzymes.

Question 15

Which aspect of enzyme structure is related to our dietary need for trace minerals?

Accepted Answer

A)  cofactor
B)  active site
C)  turnover number
D)  chirality
E)  none of these

Question 16

The theory of enzyme mechanism that suggests a flexible molecule whose shape is altered by the reaction conditions is the ________ model.

Accepted Answer

A)  coenzyme
B)  induced-fit
C)  lock-and-key
D)  substrate specific
E)  active site

Question 17

Enzymes that are affected by the binding of an activator are called

Accepted Answer

A)  zymogens.
B)  proenzymes.
C)  allosteric enzymes.
D)  induced enzymes.

Question 18

An enzyme that catalyzes addition or removal of hydrogen or oxygen on substrate molecules is a(an)

Accepted Answer

A)  ligase.
B)  isomerase.
C)  oxidoreductase.
D)  transferase.
E)  hydrolase.

Question 19

Another term for substances that bind irreversibly with the active site of an enzyme is

Accepted Answer

A)  activators.
B)  poisons.
C)  coenzymes.
D)  hormones.
E)  zymogens.

Question 20

Match the following.
-hydrolase

Accepted Answer

A)  a type of enzyme that catalyzes the breakdown of large molecules by reaction with water
B)  a type of enzyme that catalyzes the transfer of a functional group from one molecule to another
C)  a substance that prevents harmful reactions of free radicals
D)  an inactive form of an enzyme;also called a proenzyme
E)  any process which decreases the rate of an enzyme catalyzed reactionF) a type of enzyme that catalyzes the joining of two molecules togetherG) a description of the catalytic activity of an enzyme,where a small value means that very few molecules are acted on in a unit of timeH) a description of enzyme activity based on the ability of the enzyme to change shape in order to accommodate substrate moleculesI) any process that increases the rate of an enzyme catalyzed reactionJ) a type of enzyme that catalyzes the removal of a small molecule from a larger oneK) a description of enzyme activity based on an exact match between the shapes of the active site and the substrate moleculeL) a small organic molecule necessary for good health that must be obtained in the dietM) a type of enzyme that catalyzes the internal rearrangement of moleculesN) a type of enzyme that catalyzes oxidation or reduction reactions

Exam 19: Enzymes and Vitamins

Noncompetitive inhibition can be overcome by

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A form of inhibition that occurs by covalent modification is the

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An enzyme that catalyzes addition or removal of hydrogen or oxygen on substrate molecules is a(an)

Correct AnswerverifiedShow Answer

A deficiency in in which of the following has been shown to cause goiter?

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Another term for substances that bind irreversibly with the active site of an enzyme is

Correct AnswerverifiedShow Answer

A model that explains how the substrate fits exactly into the active site of an enzyme is called

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One of the enzymes involved in glycolysis is phosphofructokinase.What type of biochemical reaction is it catalyzing?

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An enzyme functions best at its optimal temperature.What would possibly happen if the temperature is increased greatly?

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Enzymes that are affected by the binding of an activator are called

Correct AnswerverifiedShow Answer

Enzymes have an optimum temperature for their catalytic activity.This is best explained by the balance between the ________ number of collisions and the ________ rate of denaturation of the enzyme as temperatures increase.

Correct AnswerverifiedShow Answer

Enzymes that are affected by the binding of an inhibitor are called

Correct AnswerverifiedShow Answer

Match the following. -induced-fit model

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Which of the following vitamins has antioxidant properties?

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Match the following. -hydrolase

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Which aspect of enzyme structure is related to our dietary need for trace minerals?

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The theory of enzyme mechanism that suggests a flexible molecule whose shape is altered by the reaction conditions is the ________ model.

Correct AnswerverifiedShow Answer

In order to have full activity,some enzymes require certain metal ions,such as Mg2+ or Zn2+.This component is called a

Correct AnswerverifiedShow Answer

When a molecule other than the correct substrate interacts with some part of an enzyme to alter the shape of the active site,the process is called

Correct AnswerverifiedShow Answer

Some enzymes are produced as zymogens because

Correct AnswerverifiedShow Answer

Substances the bind to an enzyme and increase its activity are called

Correct AnswerverifiedShow Answer

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Enzymes have an optimum temperature for their catalytic activity.This is best explained by the balance between the number of collisions and the rate of denaturation of the enzyme as temperatures increase.

Correct Answer
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In order to have full activity,some enzymes require certain metal ions,such as Mg²⁺ or Zn²⁺.This component is called a

Correct Answer
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