8.4 Multiple Choice

Question 1

How can one increase the rate of a chemical reaction?

Answer 1

Add a catalyst

Question 2

Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in

Answer 2

Breaking the bond between glucose and fructose and forming new bonds from the atoms of water

Question 3

Reactions capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reactions

Answer 3

Activation energy

Question 4

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because

Answer 4

The activation energy barrier for this reaction cannot be surmounted

Question 5

Which of the following statements regarding enzymes is true?

Answer 5

Enzymes increase the rate of a reaction

Question 6

During a laboratory experiment, you discover that an enzyme-catalyze had a ?G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ?G for the new reaction?

Answer 6

-20 kcal/mol

Question 7

The active site of an enzyme is the region that

Answer 7

Is involved in the catalytic reaction of the enzyme

Question 8

According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?

Answer 8

The binding of the substrate changes the shape of the enzymes active site

Question 9

Which curve represents the behavior of an enzyme taken from a bacterium that lives in hot springs at temperatures of 70 or higher?

Answer 9

Curve 3

Question 10

Which curve was most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?

Answer 10

Curve 4

Question 11

Which curve was most likely generated from an enzyme that requires a cofactor?

Answer 11

It is not possible to determine

Question 12

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

Answer 12

Competitive inhibition

Question 13

Which of the following is true of enzymes?

Answer 13

Enzymes increase the rate of chemical reaction by lowering activation energy barriers

Question 14

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a

Answer 14

Cofactor necessary for enzyme activity

Question 15

Based on this information, which of the following is correct?

Answer 15

Succinate is the substrate, and fumarate is the product

Question 16

What is the purpose of using malonic acid in this experiment?

Answer 16

It is a competitive inhibitor

Question 17

Which of the following terms best describes the reaction?

Answer 17

Exergonic

Question 18

Which of the following represents the ?G of the reaction?

Answer 18

D

Question 19

Which of the following would be the same in an enzyme-catalyzed or noncatalyzed reaction?

Answer 19

D

Question 20

Which of the following best describes the reaction?

Answer 20

Negative ?G, spontaneous

Question 21

Which of the following represents the difference between the free-energy content of the reaction and the free energy content of the products?

Answer 21

D

Question 22

Which of the following represents the activation energy required for the enzyme catalyzed reaction?

Answer 22

B

Question 23

Which of the following represents the activation energy required for a noncatalyzed reaction?

Answer 23

C

Question 24

Which best describes the reaction?

Answer 24

The amount of free energy released as a result of the catalyzed reaction is indicated by “d”

Question 25

Assume that the reaction has a ?G of -5.6 kcal/mol. Which of the following would be true?

Answer 25

The reaction would result in an increase in entropy and a decrease in the total energy content of the system

Question 26

In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?

Answer 26

The binding of the first two molecules must cause a 3D change that opens another active site on the enzyme

Question 27

Competitive inhibitors block the entry of substrate into the active site of an enzyme. On which of the following properties of an active site does this primarily depend?

Answer 27

The ability of an enzyme to form a template for holding and joining molecules

Question 28

Which of the following is likely to lead to an increase in the concentration of ATP in a cell?

Answer 28

An increase in a cells catabolic activity

Question 29

When you have a severe fever, what may be a grave consequence if this is not controlled?

Answer 29

Change in the folding of enzymes

Question 30

How does a non competitive inhibitor decrease the rate of an enzyme reaction?

Answer 30

By changing the shape of a reactant

Question 31

Which of the following statements describes enzyme cooperativity?

Answer 31

A substrate molecule bound to an active site affects the active site of several subunits