Question 1

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) All of the B vitamins are water-soluble.
(2) The induced-fit model for enzyme action allows for small changes in active-site geometry.
(3) Noncompetitive enzyme inhibitors bind to an enzyme at sites other than the active site.

Accepted Answer

(1) True - All B vitamins are water-soluble.
(2) True - The induced-fit model allows for small changes in active-site geometry.
(3) True - Noncompetitive enzyme inhibitors bind to an enzyme at sites other than the active site. 
Therefore, all three statements are true.

Question 2

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.

-Apoenzyme

Accepted Answer

The answer of Use the following to answer the questions...

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.

-Coenzyme

Accepted Answer

Coenzymes are components of some conjugated enzymes, not all. They are organic molecules that bind to the enzyme and are essential for its catalytic activity but are not proteins themselves.

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) 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

(1) True: B vitamins are essential for the formation of enzyme coenzymes.
(2) True: Regulatory molecules affect the activity of allosteric enzymes.
(3) False: Kinases are enzymes that transfer a phosphate group from ATP to another molecule, not isomerases. Therefore, only statements (1) and (2) are true, and the best choice is B.

Question 5

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 competitive inhibitor must resemble the substrate, and its binding to the active site of the enzyme blocks the substrate's access.

Question 6

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 nerve gases

Accepted Answer

Nerve gases are irreversible inhibitors that permanently bind to and inactivate the enzyme acetylcholinesterase, leading to an accumulation of acetylcholine and overstimulation of nerve synapses.

Question 7

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.

-Decreases enzyme activity by binding at a site other than the active site

Accepted Answer

This description matches a reversible noncompetitive inhibitor, which decreases enzyme activity by binding to an allosteric site (a site other than the enzyme's active site), thereby changing the enzyme's shape and function without directly competing with the substrate for the active site.

Question 8

Use the following to answer the questions below:
For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all.

-Conversion of a D isomer to the L isomer

Accepted Answer

The enzyme involved in converting an isomer to another isomer is called an isomerase. In this case, it specifically converts a D isomer to an L isomer. Therefore, the best choice is B) isomerase.

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.

-Mode of action of penicillins

Accepted Answer

Penicillins irreversibly inhibit the bacterial enzyme transpeptidase, which is involved in bacterial cell wall synthesis.

Question 10

Use the following to answer the questions below:
For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all.

-Introduction of a double bond by removal of hydrogen from a substrate

Accepted Answer

The introduction of a double bond by removal of hydrogen represents an oxidation reaction, which is a type of reaction carried out by oxidoreductases.

Question 11

Use the following to answer the questions below:
For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all.

-Transfer of an amino group between substrates

Accepted Answer

Transferases are enzymes that transfer a functional group from one molecule to another. In this case, the functional group is the amino group, which is being transferred between substrates.

Question 12

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 holoenzyme is an enzyme that has both protein and nonprotein parts.

Question 13

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 enzyme lactase catalyzes the hydrolysis of lactose.
(2) The spent form of vitamin E is regenerated by vitamin C.
(3) All coenzymes are cofactors but not all cofactors are coenzymes.

Accepted Answer

(1) The statement is true. Lactase is the enzyme that breaks down lactose, which is a sugar found in milk.
(2) The statement is true. Vitamin C can regenerate vitamin E by donating electrons to the spent form of vitamin E.
(3) The statement is true. Coenzymes are a type of cofactor that are organic molecules, while cofactors can be either organic or inorganic. Therefore, all coenzymes are indeed cofactors, but not all cofactors are coenzymes.

Question 14

Use the following to answer the questions below: For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all. -Removal of CO₂ from a substrate

Accepted Answer

Removal of a group from a substrate is characteristic of lyase enzymes.

Question 15

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.

-Cofactor

Accepted Answer

The answer of Use the following to answer the questions...

Question 16

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 zymogen is an inactive precursor of an enzyme that requires a specific cleavage or modification to become active.

Question 17

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.

-Forms one or more covalent bonds at an enzyme active site

Accepted Answer

Irreversible inhibitors form covalent bonds with enzymes at the active site, permanently blocking the site and preventing enzymatic activity.

Question 18

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

(1) False - Enzymes can undergo denaturation, but not all protein reactions.
(2) False - Vitamin E is not a cholesterol derivative and cannot be synthesized in the skin.
(3) True - The optimal pH range for enzyme activity is within the physiological range of 7.0 to 7.5 in the human body. Therefore, only statement (3) is true, and the answer is C.

Question 19

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 process of enzymatic browning requires the presence of oxygen.
(2) The mode of action of penicillin drugs is selective competitive reversible inhibition.
(3) Bergamottin exerts its effect on enzymes by a process called suicide inactivation.

Accepted Answer

Statement 1 is true.
Statement 2 is false; the correct mode of action is selective irreversible inhibition.
Statement 3 is false; the correct term is irreversible inactivation. 
Therefore, two out of the three statements are true.

Question 20

Use the following to answer the questions below:
For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all.

-Transfer of a phosphate group between substances

Accepted Answer

Transfer of a phosphate group between substances is a classic example of a transferase enzyme.

Quiz 21: Enzymes and Vitamins

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. -Apoenzyme

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. -Coenzyme

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 nerve gases

Use the following to answer the questions below: For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all. -Conversion of a D isomer to the L isomer

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

Use the following to answer the questions below: For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all. -Introduction of a double bond by removal of hydrogen from a substrate

Use the following to answer the questions below: For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all. -Transfer of an amino group between substrates

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 enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all. -Removal of CO2 from a substrate

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. -Cofactor

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

Use the following to answer the questions below: For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all. -Transfer of a phosphate group between substances

Use the following to answer the questions below: For each of the enzyme actions, choose the general enzyme type from the response list. Responses may be used more than once or need not be used at all. -Removal of CO₂ from a substrate