Question 1

The optimum pH for the activity of pepsin is about ________.

Accepted Answer

A) 2.0 
B) 4.0 
C) 6.5 
D) 7.4 
E) 7.6 
A) 2.0 
B) 4.0 
C) 6.5 
D) 7.4 
E) 7.6

Question 2

A noncompetitive inhibitor

Accepted Answer

A) binds at the active site of the enzyme. 
B) alters the three-dimensional structure of the enzyme. 
C) increases the rate of the enzyme-catalyzed reaction. 
D) has a structure similar to the substrate. 
E) has its effect reversed by adding more substrate. 
A) binds at the active site of the enzyme. 
B) alters the three-dimensional structure of the enzyme. 
C) increases the rate of the enzyme-catalyzed reaction. 
D) has a structure similar to the substrate. 
E) has its effect reversed by adding more substrate.

Question 3

Pyruvate carboxylase is an example of a ligase enzyme.

Accepted Answer

A) True 
 B)False

Question 4

Compared to an uncatalyzed reaction, an enzyme-catalyzed reaction

Accepted Answer

A) uses less substrate. 
B) produces different products. 
C) occurs at a faster rate. 
D) requires more energy. 
E) requires a higher temperature. 
A) uses less substrate. 
B) produces different products. 
C) occurs at a faster rate. 
D) requires more energy. 
E) requires a higher temperature.

Question 5

The optimum pH of most cellular enzymes is about 7.4.

Accepted Answer

A) True 
 B)False

Question 6

In the lock-and-key model of enzyme action, the enzyme active site is thought of as

Accepted Answer

A) a rigid, nonflexible shape that fits the substrate exactly. 
B) an area of the enzyme that can adjust to fit the substrate shape. 
C) a key-like shape that fits into a pocket of the substrate surface. 
D) a hydrophilic area on the enzyme surface. 
E) a lock that bars a noncompetitive inhibitor from reacting. 
A) a rigid, nonflexible shape that fits the substrate exactly. 
B) an area of the enzyme that can adjust to fit the substrate shape. 
C) a key-like shape that fits into a pocket of the substrate surface. 
D) a hydrophilic area on the enzyme surface. 
E) a lock that bars a noncompetitive inhibitor from reacting.

Question 7

The surface of a freshly cut apple turns brown because of

Accepted Answer

A) inhibition of the surface enzymes by nitrogen. 
B) interaction of the surface enzymes with oxygen. 
C) a change in pH at the surface. 
D) an increase in substrate concentration at the cut surface. 
E) the presence of vitamin C in the apple. 
A) inhibition of the surface enzymes by nitrogen. 
B) interaction of the surface enzymes with oxygen. 
C) a change in pH at the surface. 
D) an increase in substrate concentration at the cut surface. 
E) the presence of vitamin C in the apple.

Question 8

An increase in concentration of the enzyme LDH in the blood can be used to detect

Accepted Answer

A) heart attack. 
B) kidney damage. 
C) anemia. 
D) uremia. 
E) bulimia. 
A) heart attack. 
B) kidney damage. 
C) anemia. 
D) uremia. 
E) bulimia.

Question 9

Enzymes always require a cofactor.

Accepted Answer

A) True 
 B)False

Question 10

To what main class of enzymes does the enzyme that catalyzes the following reaction belong?

Accepted Answer

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

Question 11

A biological catalyst is called a(n) ________.

Accepted Answer

A) lipid 
B) enzyme 
C) cofactor 
D) coenzyme 
E) substrate 
A) lipid 
B) enzyme 
C) cofactor 
D) coenzyme 
E) substrate

Question 12

Some insecticides kill insects by inhibiting the enzyme

Accepted Answer

A) alcohol dehydrogenase. 
B) acetylcholinesterase. 
C) creatine kinase. 
D) lipase. 
E) penicillinase. 
A) alcohol dehydrogenase. 
B) acetylcholinesterase. 
C) creatine kinase. 
D) lipase. 
E) penicillinase.

Question 13

Consider an enzymatic reaction in which the initial concentration of substrate is low. If the amount of enzyme is held constant, but the amount of substrate is increased, the rate of an enzyme catalyzed reaction will

Accepted Answer

A) increase in an exponential fashion. 
B) decrease at first, then increase in a linear fashion. 
C) increase at first in a linear fashion, then remain at a constant high rate. 
D) stay the same. 
E) be inhibited by the higher concentrations of substrate. 
A) increase in an exponential fashion. 
B) decrease at first, then increase in a linear fashion. 
C) increase at first in a linear fashion, then remain at a constant high rate. 
D) stay the same. 
E) be inhibited by the higher concentrations of substrate.

Question 14

In the induced fit model of enzyme activity, both the enzyme and the substrate change shape.

Accepted Answer

A) True 
 B)False

Question 15

Indicate whether each of the following is fat soluble or water soluble.
-folic acid

Accepted Answer

The answer of Indicate whether each of the following is...

Question 16

Indicate whether each of the following is fat soluble or water soluble.
-vitamin B6

Accepted Answer

The answer of Indicate whether each of the following is...

Question 17

Urea is converted to ammonia and carbon dioxide by the action of urease. What will be the effect on the rate if the temperature of the reaction is lowered from 37 °C (the optimum temperature) to 27 °C?

Accepted Answer

A) There will be no effect. 
B) The rate will slow down. 
C) The rate will double. 
D) The rate will triple. 
E) The rate will slow down, then speed up again. 
A) There will be no effect. 
B) The rate will slow down. 
C) The rate will double. 
D) The rate will triple. 
E) The rate will slow down, then speed up again.

Question 18

Hexokinase catalyzes only the addition of phosphate to any hexose sugar. This type of activity is called

Accepted Answer

A) regional specificity. 
B) collateral specificity. 
C) group specificity. 
D) noncompetitive specificity. 
E) general specificity. 
A) regional specificity. 
B) collateral specificity. 
C) group specificity. 
D) noncompetitive specificity. 
E) general specificity.

Question 19

The active site is a large part of an enzyme.

Accepted Answer

A) True 
 B)False

Question 20

Metal ions such as Zn2+ and Fe3+ are often needed by enzymes as

Accepted Answer

A) isozymes. 
B) allosteres. 
C) inhibitors. 
D) cofactors. 
E) substrates. 
A) isozymes. 
B) allosteres. 
C) inhibitors. 
D) cofactors. 
E) substrates.

Exam 20: Enzymes and Vitamins

The optimum pH for the activity of pepsin is about ________.

A noncompetitive inhibitor

Pyruvate carboxylase is an example of a ligase enzyme.

Compared to an uncatalyzed reaction, an enzyme-catalyzed reaction

The optimum pH of most cellular enzymes is about 7.4.

In the lock-and-key model of enzyme action, the enzyme active site is thought of as

The surface of a freshly cut apple turns brown because of

An increase in concentration of the enzyme LDH in the blood can be used to detect

Enzymes always require a cofactor.

To what main class of enzymes does the enzyme that catalyzes the following reaction belong?

A biological catalyst is called a(n) ________.

Some insecticides kill insects by inhibiting the enzyme

Consider an enzymatic reaction in which the initial concentration of substrate is low. If the amount of enzyme is held constant, but the amount of substrate is increased, the rate of an enzyme catalyzed reaction will

In the induced fit model of enzyme activity, both the enzyme and the substrate change shape.

Indicate whether each of the following is fat soluble or water soluble. -folic acid

Indicate whether each of the following is fat soluble or water soluble. -vitamin B6

Urea is converted to ammonia and carbon dioxide by the action of urease. What will be the effect on the rate if the temperature of the reaction is lowered from 37 °C (the optimum temperature) to 27 °C?

Hexokinase catalyzes only the addition of phosphate to any hexose sugar. This type of activity is called

The active site is a large part of an enzyme.

Metal ions such as Zn2+ and Fe3+ are often needed by enzymes as

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Metal ions such as Zn²⁺ and Fe³⁺ are often needed by enzymes as