Deck 21: Enzymes and Vitamins

Question 1

The protein portion of a conjugated enzyme is called a(n).

A) apoenzyme
B) coenzyme
C) holoenzyme
D) cofactor

Answer 1

apoenzyme

Question 2

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

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

Answer 2

components of coenzymes

Question 3

The number of known vitamins is

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

Answer 3

13

Question 4

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

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 5

Which of the following is always present in both conjugated enzymes and simple enzymes?

A) protein
B) a vitamin
C) a cofactor
D) a coenzyme

Question 6

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

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 7

In which of the following is the pairing between enzyme type and enzyme function incorrect?

A) carbohydrases - hydrolysis of glycosidic bonds in carbohydrates
B) oxidase - oxidation of a substrate
C) mutase - conversion of one structural isomer into another
D) dehydrogenase - removal of water from substrate

Question 8

The number of substrate molecules acted upon per minute by one molecule of enzyme is called the

A) active site number
B) enzyme activity number
C) turnover number
D) optimum number

Question 9

Which of the following substance is a zymogen?

A) angiotensin
B) pepsin
C) pepsinogen
D) elastase

Question 10

All of the B vitamins, except one, contain heterocyclic nitrogen ring systems as part of their structure. The exception is

A) riboflavin
B) thiamin
C) pantothenic acid
D) biotin

Question 11

The final product of a series of enzyme-catalyzed reactions causes the enzyme that catalyzes the first reaction of the series to be inhibited. This is an example of

A) positive regulator control
B) substrate control
C) feedback control
D) competitive control

Question 12

In which of the following pairs of vitamins are both members of the pair water-soluble?

A) vitamin E and thiamin
B) vitamin A and vitamin K
C) vitamin E and vitamin B₆
D) niacin and pantothenic acid

Question 13

An enzyme that catalyzes the oxidation of only one kind of alcohol would be described as showing

A) group specificity
B) stereochemical specificity
C) linkage specificity
D) absolute specificity

Question 14

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

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 15

Vitamins C and E are important, respectively, in

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

Question 16

Which of the following enzyme properties is explained by the lock-and-key model for enzyme action?

A) high turnover rate
B) absolute specificity
C) susceptibility to denaturation
D) susceptibility to deactivation

Question 17

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

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 18

What is the function of enzymes within living systems?

A) structural elements
B) neurotransmitters
C) catalysts
D) hormones

Question 19

Enzymes have names that

A) always end with -ise
B) always end with -in
C) can end with either -ase or -in
D) can end with either -ase or -ogen

Question 20

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

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

Question 21

Which of the following statements concerning the effect of temperature change on an enzyme-catalyzed reaction is incorrect?

A) An increase in temperature can stop the reaction by denaturing the enzyme.
B) An increase in temperature can increase the reaction rate by increasing the speed at which molecules move.
C) An increase in temperature to the optimum temperature maximizes reaction rate.
D) More than one correct response.
E) No correct response.

Question 22

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

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 23

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) A substrate is the substance upon which an enzyme "acts."
(2) Competitive enzyme inhibition is a reversible process.
(3) Vitamin C is necessary for the formation of the structural protein collagen.

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 24

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 active site of an enzyme always contains one or more metal atoms.
(2) The water-soluble vitamins are the B vitamins and vitamins A and C.
(3) An enzyme's turnover number is the rate at which it is degraded and resynthesized within the human body.

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 25

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

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

Question 26

Which of the following statements concerning sources for B vitamins is correct?

A) Most fruits are poor sources.
B) Most vegetables are good sources.
C) Meat and dairy products are good sources.
D) More than one correct response.
E) No correct response.

Question 27

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.

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 28

Which of the following pairings of vitamins and functions is correct?

A) vitamin E; an antioxidant
B) vitamin C; a coenzyme
C) vitamin D; maintenance of mucous membranes
D) more than one correct response
E) no correct response

Question 29

In which of the following pairs of terms do the two terms have the same meaning?

A) holoenzyme and conjugated enzyme
B) coenzyme and simple enzyme
C) apoenzyme and cofactor
D) more than one correct response
E) no correct response

Question 30

Which of the following is not a water-soluble vitamin?

A) vitamin C
B) vitamin A
C) vitamin D
D) more than one correct response
E) no correct response

Question 31

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 primary function of vitamin D in the body is that of an antioxidant.
(2) Holoenzymes are conjugated enzymes.
(3) An increase in enzyme activity is always associated with an increase in the temperature of an enzyme-containing system.

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 32

Which of the following would be the name for an enzyme?

A) succinate dehydrogenase
B) pyruvate
C) pepsin
D) more than one correct response
E) no correct response

Question 33

In which of the following pairs of enzymes is the first listed enzyme more limited in its scope than the second listed enzyme?

A) linkage-specific enzyme, absolute-specific enzyme
B) stereochemical-specific enzyme, linkage-specific enzyme
C) group-specific enzyme, stereochemical-specific enzyme
D) more than one correct response
E) no correct response

Question 34

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

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.

Question 35

Which of the following could be a component of a conjugated enzyme?

A) coenzyme
B) cofactor
C) apoenzyme
D) more than one correct response
E) no correct response

Question 36

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) Activation of a zymogen produces a proteolytic enzyme.
(2) An enzyme-substrate complex is the final product in most enzyme-catalyzed reactions.
(3) Three forms of vitamin A are active in the human body.

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 37

Which of the following B vitamins has a structure in which a metal atom is present?

A) folate
B) biotin
C) vitamin B₁₂
D) more than one correct response
E) no correct response

Question 38

Which of the following binds to an enzyme at its active site?

A) irreversible inhibitor
B) reversible competitive inhibitor
C) reversible noncompetitive inhibitor
D) more than one correct response
E) no correct response

Question 39

Which of the following pairings of terms is correct?

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 40

An enzyme active site is the location in an enzyme where substrate molecules

A) are generated
B) become catalysts
C) undergo change
D) more than one correct response
E) no correct response

Question 41

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.

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 42

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

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 43

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

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 44

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.

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 45

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

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

Question 46

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

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

Question 47

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

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

Question 48

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

A) lyase
B) isomerase
C) transferase
D) oxidoreductase

Question 49

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

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

Question 50

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

A) lyase
B) isomerase
C) transferase
D) oxidoreductase

Question 51

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

A) lyase
B) isomerase
C) transferase
D) oxidoreductase

Question 52

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

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 53

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.

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 54

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

A) lyase
B) isomerase
C) transferase
D) oxidoreductase

Question 55

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

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 56

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

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 57

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

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

Question 58

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.

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 59

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.

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 60

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

A) lyase
B) isomerase
C) transferase
D) oxidoreductase

Question 61

Use the following to answer the questions below:
Below are descriptions of the variables needed to plot a graph on which enzyme activity is the y-axis. For each description choose from the response list the "shape" of the resulting graph. Choices may be used more than once or need not be used at all.
Increase in substrate concentration with all other variables constant

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

Question 62

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.

Important in the blood-clotting process

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

Question 63

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.

Structure contains a cobalt atom

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

Question 64

Use the following to answer the questions below:
Below are descriptions of the variables needed to plot a graph on which enzyme activity is the y-axis. For each description choose from the response list the "shape" of the resulting graph. Choices may be used more than once or need not be used at all.
Increase in enzyme concentration with all other variables constant

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

Question 65

Use the following to answer the questions below:
Below are descriptions of the variables needed to plot a graph on which enzyme activity is the y-axis. For each description choose from the response list the "shape" of the resulting graph. Choices may be used more than once or need not be used at all.
Increase in temperature up to the optimum temperature with all other variables constant

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

Question 66

Use the following to answer the questions below:
Below are descriptions of the variables needed to plot a graph on which enzyme activity is the y-axis. For each description choose from the response list the "shape" of the resulting graph. Choices may be used more than once or need not be used at all.
Increase in pH with all other variables constant

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

Question 67

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.

Structural derivative of cholesterol

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

Question 68

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

Question 69

Use the following to answer the questions below:
Below are descriptions of the variables needed to plot a graph on which enzyme activity is the y-axis. For each description choose from the response list the "shape" of the resulting graph. Choices may be used more than once or need not be used at all.
Increase in temperature beginning at the optimum temperature with all other variables constant

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

Question 70

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.

Cosubstrate in the formation of the structural protein collagen

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