Question 1

Which of the following statements concerning enzyme active sites is incorrect?

Accepted Answer

A)  They generally involve only a small portion of the enzyme. 
B)  Noncompetitive inhibitors can change active site shape. 
C)  The lock-and-key model of enzyme activity assumes that an active site has a fixed, rigid geometrical conformation. 
D)  More than one correct response. 
E)  No correct response. 
A)  They generally involve only a small portion of the enzyme. 
B)  Noncompetitive inhibitors can change active site shape. 
C)  The lock-and-key model of enzyme activity assumes that an active site has a fixed, rigid geometrical conformation. 
D)  More than one correct response. 
E)  No correct response. E

Question 2

Vitamins C and E are important, respectively, in

Accepted Answer

A)  bone formation and antioxidant activity 
B)  bone formation and proper use of calcium and phosphorus 
C)  vision and blood clotting 
D)  vision and proper use of calcium and phosphorus 
A)  bone formation and antioxidant activity 
B)  bone formation and proper use of calcium and phosphorus 
C)  vision and blood clotting 
D)  vision and proper use of calcium and phosphorus A

Question 3

Use the following to answer the questions below:
Match each of the enzyme descriptions with an appropriate characterization from the response list. Responses may be used more than once or need not be used at all.

-Zymogen

Accepted Answer

A)  component of all conjugated enzymes 
B)  component of some conjugated enzymes 
C)  has both protein and nonprotein parts 
D)  inactive precursor of an enzyme 
A)  component of all conjugated enzymes 
B)  component of some conjugated enzymes 
C)  has both protein and nonprotein parts 
D)  inactive precursor of an enzyme D

Question 4

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
-Statements: (1) An apoenzyme, by itself, has no biochemical activity.
(2) Urease is an example of an enzyme with absolute specificity.
(3) All enzymes have names that end in -ase.

Accepted Answer

A)  All three statements are true. 
B)  Two of the three statements are true. 
C)  Only one of the statements is true. 
D)  None of the statements is true. 
A)  All three statements are true. 
B)  Two of the three statements are true. 
C)  Only one of the statements is true. 
D)  None of the statements is true.

Question 5

Which of the following statements about a competitive inhibitor is correct?

Accepted Answer

A)  It must resemble the substrate in general shape. 
B)  Its effect can be diminished by increasing substrate concentration. 
C)  It and the normal substrate simultaneously occupy the active site. 
D)  More than one correct response. 
E)  No correct response. 
A)  It must resemble the substrate in general shape. 
B)  Its effect can be diminished by increasing substrate concentration. 
C)  It and the normal substrate simultaneously occupy the active site. 
D)  More than one correct response. 
E)  No correct response.

Question 6

Use the following to answer the questions below:
Match each of the enzyme descriptions with an appropriate characterization from the response list. Responses may be used more than once or need not be used at all.

-Holoenzyme

Accepted Answer

A)  component of all conjugated enzymes 
B)  component of some conjugated enzymes 
C)  has both protein and nonprotein parts 
D)  inactive precursor of an enzyme 
A)  component of all conjugated enzymes 
B)  component of some conjugated enzymes 
C)  has both protein and nonprotein parts 
D)  inactive precursor of an enzyme

Question 7

Use the following to answer the questions below:
For each of the descriptions of a vitamin, select from the response list the name of the vitamin. Responses may be used more than once or need not be used at all.

-Water-soluble vitamin that is not a B vitamin

Accepted Answer

A)  vitamin D 
B)  vitamin C 
C)  vitamin K 
D)  vitamin B12 
A)  vitamin D 
B)  vitamin C 
C)  vitamin K 
D)  vitamin B12

Question 8

A plot of enzyme activity (y-axis) versus substrate concentration (x-axis) with other variables constant is a

Accepted Answer

A)  straight line with an upward slope 
B)  line with an upward slope and a long flat top 
C)  line with an upward slope followed by a downward slope 
D)  straight horizontal line 
A)  straight line with an upward slope 
B)  line with an upward slope and a long flat top 
C)  line with an upward slope followed by a downward slope 
D)  straight horizontal line

Question 9

Use the following to answer the questions below:
For each of the descriptions of "enzyme action," choose from the response list the type of inhibitor or regulator that is involved. Responses may be used more than once or need not be used at all.

-Must resemble a substrate closely in shape and charge distribution

Accepted Answer

A)  reversible competitive inhibitor 
B)  reversible noncompetitive inhibitor 
C)  irreversible inhibitor 
D)  positive regulator 
A)  reversible competitive inhibitor 
B)  reversible noncompetitive inhibitor 
C)  irreversible inhibitor 
D)  positive regulator

Question 10

An enzyme active site is the location in the enzyme where:

Accepted Answer

A)  The actual catalysis occurs. 
B)  The side groups of the protein interact with the catalyst. 
C)  The catalyst creates the substrate molecules. 
D)  The substrate molecules are created. 
A)  The actual catalysis occurs. 
B)  The side groups of the protein interact with the catalyst. 
C)  The catalyst creates the substrate molecules. 
D)  The substrate molecules are created.

Question 11

Use the following to answer the questions below:
For each of the descriptions of "enzyme action," choose from the response list the type of inhibitor or regulator that is involved. Responses may be used more than once or need not be used at all.

-Mode of action of penicillins

Accepted Answer

A)  reversible competitive inhibitor 
B)  reversible noncompetitive inhibitor 
C)  irreversible inhibitor 
D)  positive regulator 
A)  reversible competitive inhibitor 
B)  reversible noncompetitive inhibitor 
C)  irreversible inhibitor 
D)  positive regulator

Question 12

In which of the following pairs of substances are both members of the pair zymogens?

Accepted Answer

A)  pepsin and pepsinogen 
B)  proelastase and elastase 
C)  prothrombin and pepsinogen 
D)  more than one correct response 
E)  no correct response 
A)  pepsin and pepsinogen 
B)  proelastase and elastase 
C)  prothrombin and pepsinogen 
D)  more than one correct response 
E)  no correct response

Question 13

Which of the following statements concerning a competitive enzyme inhibitor is correct?

Accepted Answer

A)  It resembles the substrate in charge distribution. 
B)  It forms a strong covalent bond to an amino acid side-chain group at a site other than the active site. 
C)  Its effect is never reversible. 
D)  Its effect can be overcome by increasing the inhibitor concentration. 
A)  It resembles the substrate in charge distribution. 
B)  It forms a strong covalent bond to an amino acid side-chain group at a site other than the active site. 
C)  Its effect is never reversible. 
D)  Its effect can be overcome by increasing the inhibitor concentration.

Question 14

The number of known vitamins is

Accepted Answer

A)  10 
B)  13 
C)  15 
D)  20 
A)  10 
B)  13 
C)  15 
D)  20

Question 15

Which of the following pairings of terms is correct?

Accepted Answer

A)  A kinase is a transferase 
B)  A mutase is a ligase 
C)  A synthase is a lyase 
D)  more than one correct response 
E)  no correct response 
A)  A kinase is a transferase 
B)  A mutase is a ligase 
C)  A synthase is a lyase 
D)  more than one correct response 
E)  no correct response

Question 16

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
-Statements: (1) Enzymes undergo all of the reactions of proteins including denaturation.
(2) Vitamin E, a cholesterol derivative, can be synthesized in the skin by sunlight irradiation.
(3) The optimum pH for enzyme activity within the human body is always within the physiological pH range of 7.0 to 7.5.

Accepted Answer

A)  All three statements are true. 
B)  Two of the three statements are true. 
C)  Only one of the statements is true. 
D)  None of the statements is true. 
A)  All three statements are true. 
B)  Two of the three statements are true. 
C)  Only one of the statements is true. 
D)  None of the statements is true.

Question 17

Use the following to answer the questions below:
In each of the following multiple-choice questions, characterize EACH of the three given statements as being TRUE or FALSE and then indicate the collective true-false status of the statements using the choices:
-Statements: (1) The B vitamins serve as precursors for enzyme cofactors.
(2) Associated with allosteric enzyme action are substances known as regulators.
(3) Kinases belong to the class of enzymes called isomerases.

Accepted Answer

A)  All three statements are true. 
B)  Two of the three statements are true. 
C)  Only one of the statements is true. 
D)  None of the statements is true. 
A)  All three statements are true. 
B)  Two of the three statements are true. 
C)  Only one of the statements is true. 
D)  None of the statements is true.

Question 18

Which of the following binds to an enzyme at a location other than the active site?

Accepted Answer

A)  substrate 
B)  irreversible inhibitor 
C)  reversible competitive inhibitor 
D)  reversible noncompetitive inhibitor 
A)  substrate 
B)  irreversible inhibitor 
C)  reversible competitive inhibitor 
D)  reversible noncompetitive inhibitor

Question 19

A plot of enzyme activity (y-axis) versus pH (x-axis) with other variables constant is a

Accepted Answer

A)  straight line with an upward slope 
B)  line with an upward slope and a long flat top 
C)  line with an upward slope followed by a downward slope 
D)  straight horizontal line 
A)  straight line with an upward slope 
B)  line with an upward slope and a long flat top 
C)  line with an upward slope followed by a downward slope 
D)  straight horizontal line

Question 20

The major function for B vitamins within the human body is as

Accepted Answer

A)  antioxidants 
B)  components of coenzymes 
C)  regulators of cell differentiation 
D)  regulators of calcium ion and phosphate ion concentrations in blood 
A)  antioxidants 
B)  components of coenzymes 
C)  regulators of cell differentiation 
D)  regulators of calcium ion and phosphate ion concentrations in blood

Exam 21: Enzymes and Vitamins

Which of the following statements concerning enzyme active sites is incorrect?

Vitamins C and E are important, respectively, in

Use the following to answer the questions below: Match each of the enzyme descriptions with an appropriate characterization from the response list. Responses may be used more than once or need not be used at all. -Zymogen

Which of the following statements about a competitive inhibitor is correct?

Use the following to answer the questions below: Match each of the enzyme descriptions with an appropriate characterization from the response list. Responses may be used more than once or need not be used at all. -Holoenzyme

Use the following to answer the questions below: For each of the descriptions of a vitamin, select from the response list the name of the vitamin. Responses may be used more than once or need not be used at all. -Water-soluble vitamin that is not a B vitamin

A plot of enzyme activity (y-axis) versus substrate concentration (x-axis) with other variables constant is a

An enzyme active site is the location in the enzyme where:

Use the following to answer the questions below: For each of the descriptions of "enzyme action," choose from the response list the type of inhibitor or regulator that is involved. Responses may be used more than once or need not be used at all. -Mode of action of penicillins

In which of the following pairs of substances are both members of the pair zymogens?

Which of the following statements concerning a competitive enzyme inhibitor is correct?

The number of known vitamins is

Which of the following pairings of terms is correct?

Which of the following binds to an enzyme at a location other than the active site?

A plot of enzyme activity (y-axis) versus pH (x-axis) with other variables constant is a

The major function for B vitamins within the human body is as

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