Question 1

Where is the enzyme arginase produced in the human body?

Accepted Answer

A)  the liver 
B)  the pancreas 
C)  the small intestine 
D)  the stomach 
A)  the liver 
B)  the pancreas 
C)  the small intestine 
D)  the stomach A

Question 2

The names of enzymes are often derived from which of the following?

Accepted Answer

A)  the reaction they catalyze 
B)  the compound on which they act 
C)  the reaction they catalyze and the compound on which they act 
D)  none of these 
A)  the reaction they catalyze 
B)  the compound on which they act 
C)  the reaction they catalyze and the compound on which they act 
D)  none of these C

Question 3

Which of the following reactions is catalyzed by a hydrolase?

Accepted Answer

A)  the conversion of lactate to pyruvate 
B)  the conversion of aspartate to glutamate and oxaloacetate 
C)  the conversion of acetylcholine to acetic acid and choline 
D)  the conversion of aconitate to isocitrate 
A)  the conversion of lactate to pyruvate 
B)  the conversion of aspartate to glutamate and oxaloacetate 
C)  the conversion of acetylcholine to acetic acid and choline 
D)  the conversion of aconitate to isocitrate C

Question 4

Consider the following image depicting enzyme behavior.   Which of the following correctly characterizes the components of this model?

Accepted Answer

A)  A - enzyme, B - substrate, C - active site, D - E-S complex 
B)  A - substrate, B - active site, C - enzyme, D - E-S complex 
C)  A - active site, B - substrate, C - E-S complex, D - enzyme 
D)  A - substrate, B - enzyme, D - E-S complex, D - active site 
A)  A - enzyme, B - substrate, C - active site, D - E-S complex 
B)  A - substrate, B - active site, C - enzyme, D - E-S complex 
C)  A - active site, B - substrate, C - E-S complex, D - enzyme 
D)  A - substrate, B - enzyme, D - E-S complex, D - active site

Question 5

Which of the following statements is true of enzymes?

Accepted Answer

A)  They lower the activation energy of a chemical reaction. 
B)  They are extremely specific. 
C)  They lower the activation energy of a chemical reaction and they are extremely specific. 
D)  None of these 
A)  They lower the activation energy of a chemical reaction. 
B)  They are extremely specific. 
C)  They lower the activation energy of a chemical reaction and they are extremely specific. 
D)  None of these

Question 6

What is the optimum pH range for the activity of the enzyme pepsin?

Accepted Answer

A)  1.5-2.0 
B)  6.7-7.0 
C)  3.5-4.5 
D)  8.8-9.2 
A)  1.5-2.0 
B)  6.7-7.0 
C)  3.5-4.5 
D)  8.8-9.2

Question 7

Which of the following statements is true of chymotrypsinogen?

Accepted Answer

A)  It is the active form of trypsinogen. 
B)  It consists of a single polypeptide chain that is 100 residues long. 
C)  It is formed in the pancreas. 
D)  It has 20 disulfide bonds. 
A)  It is the active form of trypsinogen. 
B)  It consists of a single polypeptide chain that is 100 residues long. 
C)  It is formed in the pancreas. 
D)  It has 20 disulfide bonds.

Question 8

Which of the following processes is commonly associated with protein modification?

Accepted Answer

A)  phosphorylation 
B)  positive modulation 
C)  phosphorylation and positive modulation 
D)  none of these 
A)  phosphorylation 
B)  positive modulation 
C)  phosphorylation and positive modulation 
D)  none of these

Question 9

In which type of inhibition does an inhibitor bind to the active site of an enzyme?

Accepted Answer

A)  cooperative inhibition 
B)  competitive inhibition 
C)  noncompetitive inhibition 
D)  selective inhibition 
A)  cooperative inhibition 
B)  competitive inhibition 
C)  noncompetitive inhibition 
D)  selective inhibition

Question 10

Which of the following changes can cause enzyme activity to either increase or decrease?

Accepted Answer

A)  an increase in enzyme concentration 
B)  a change in the pH 
C)  an increase in the enzyme concentration and a change in the pH 
D)  none of these 
A)  an increase in enzyme concentration 
B)  a change in the pH 
C)  an increase in the enzyme concentration and a change in the pH 
D)  none of these

Question 11

Which of the following is an intermediate in an enzyme-catalyzed reaction?

Accepted Answer

A)  an apoenzyme 
B)  a coenzyme-substrate complex 
C)  an enzyme-substrate complex 
D)  a zymogen 
A)  an apoenzyme 
B)  a coenzyme-substrate complex 
C)  an enzyme-substrate complex 
D)  a zymogen

Question 12

Which of the following statements is true of isozymes?

Accepted Answer

A)  They are two different enzymes that have the same function. 
B)  They are a pair of enzymes that must both be present for enzyme inhibition. 
C)  They are different forms of the same enzyme produced in different tissues. 
D)  None of these are true. 
A)  They are two different enzymes that have the same function. 
B)  They are a pair of enzymes that must both be present for enzyme inhibition. 
C)  They are different forms of the same enzyme produced in different tissues. 
D)  None of these are true.

Question 13

How many subunits does lactate dehydrogenase contain?

Accepted Answer

A)  4 
B)  2 
C)  10 
D)  6 
A)  4 
B)  2 
C)  10 
D)  6

Question 14

Which of the following statements is true of enzymes?

Accepted Answer

A)  They shift the position of chemical equilibrium. 
B)  They increase the rate of a chemical reaction. 
C)  They shift the position of chemical equilibrium and they increase the rate of a chemical reaction. 
D)  None of these 
A)  They shift the position of chemical equilibrium. 
B)  They increase the rate of a chemical reaction. 
C)  They shift the position of chemical equilibrium and they increase the rate of a chemical reaction. 
D)  None of these

Question 15

Which of the following types of molecules reduce the activity of an enzyme?

Accepted Answer

A)  zymogens 
B)  inhibitors 
C)  isozymes 
D)  substrates 
A)  zymogens 
B)  inhibitors 
C)  isozymes 
D)  substrates

Question 16

In which type of inhibition is it not possible to restore the maximum rate of enzyme activity by adding additional substrate?

Accepted Answer

A)  cooperative inhibition 
B)  competitive inhibition 
C)  induced-fit inhibition 
D)  irreversible inhibition 
A)  cooperative inhibition 
B)  competitive inhibition 
C)  induced-fit inhibition 
D)  irreversible inhibition

Question 17

Tyrosine-tRNA synthetase belongs to which group of enzymes?

Accepted Answer

A)  hydrolases 
B)  ligases 
C)  oxidoreductases 
D)  transferases 
A)  hydrolases 
B)  ligases 
C)  oxidoreductases 
D)  transferases

Question 18

Identify the optimum pH for the activity of the enzyme lipase.

Accepted Answer

A)  8.0 
B)  6.0 
C)  9.7 
D)  2.0 
A)  8.0 
B)  6.0 
C)  9.7 
D)  2.0

Question 19

What name is given to a molecule on which an enzyme works?

Accepted Answer

A)  cofactor 
B)  isozyme 
C)  substrate 
D)  zymogen 
A)  cofactor 
B)  isozyme 
C)  substrate 
D)  zymogen

Question 20

Which of the following statements is true of allosteric enzymes?

Accepted Answer

A)  They always consist 006Ff one polypeptide chain or subunit. 
B)  They have a nonprotein portion. 
C)  They have more than one active site on each subunit. 
D)  The active site and regulatory site can be present on the same subunit. 
A)  They always consist 006Ff one polypeptide chain or subunit. 
B)  They have a nonprotein portion. 
C)  They have more than one active site on each subunit. 
D)  The active site and regulatory site can be present on the same subunit.

Exam 22: Enzymes

Where is the enzyme arginase produced in the human body?

The names of enzymes are often derived from which of the following?

Which of the following reactions is catalyzed by a hydrolase?

Consider the following image depicting enzyme behavior. Which of the following correctly characterizes the components of this model?

Which of the following statements is true of enzymes?

What is the optimum pH range for the activity of the enzyme pepsin?

Which of the following statements is true of chymotrypsinogen?

Which of the following processes is commonly associated with protein modification?

In which type of inhibition does an inhibitor bind to the active site of an enzyme?

Which of the following changes can cause enzyme activity to either increase or decrease?

Which of the following is an intermediate in an enzyme-catalyzed reaction?

Which of the following statements is true of isozymes?

How many subunits does lactate dehydrogenase contain?

Which of the following statements is true of enzymes?

Which of the following types of molecules reduce the activity of an enzyme?

In which type of inhibition is it not possible to restore the maximum rate of enzyme activity by adding additional substrate?

Tyrosine-tRNA synthetase belongs to which group of enzymes?

Identify the optimum pH for the activity of the enzyme lipase.

What name is given to a molecule on which an enzyme works?

Which of the following statements is true of allosteric enzymes?

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