Name: 
 

Chaper 8: Enzymology and Catalysis



Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 

 1. 

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
a.
catalysis
b.
metabolism
c.
anabolism
d.
dehydration
e.
catabolism
 

 2. 

According to the first law of thermodynamics,
a.
the universe loses energy because of heat production.
b.
systems rich in energy are intrinsically unstable and will give up energy with time.
c.
energy can be neither created nor destroyed.
d.
A and B only
e.
A, B, and C
 

 3. 

Which of the following types of reactions would decrease the entropy within a cell?
a.
dehydration reactions
b.
hydrolysis
c.
respiration
d.
digestion
e.
catabolism
 

 4. 

The mathematical expression for the change in free energy of a system is: chpt8_files/i0050000.jpgG = chpt8_files/i0050001.jpgH - Tchpt8_files/i0050002.jpgS. Which of the following is (are) incorrect?
a.
chpt8_files/i0050003.jpgS is the change in entropy, a measure of randomness.
b.
chpt8_files/i0050004.jpgH is the change in enthalpy, the energy available to do work.
c.
chpt8_files/i0050005.jpgG is the change in free energy.
d.
T is the absolute temperature.
e.
both A and B
 

 5. 

When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows:
a.
+chpt8_files/i0060000.jpgG, +chpt8_files/i0060001.jpgH, +chpt8_files/i0060002.jpgS
b.
+chpt8_files/i0060003.jpgG, +chpt8_files/i0060004.jpgH, -chpt8_files/i0060005.jpgS
c.
+chpt8_files/i0060006.jpgG, -chpt8_files/i0060007.jpgH, -chpt8_files/i0060008.jpgS
d.
-chpt8_files/i0060009.jpgG, +chpt8_files/i0060010.jpgH, +chpt8_files/i0060011.jpgS
e.
-chpt8_files/i0060012.jpgG, -chpt8_files/i0060013.jpgH, -chpt8_files/i0060014.jpgS
 

 6. 

A chemical reaction that has a positive chpt8_files/i0070000.jpgG is correctly described as
a.
endergonic.
b.
endothermic.
c.
enthalpic.
d.
spontaneous.
e.
exothermic.
 

 7. 

The hydrolysis of ATP to ADP and inorganic phosphate (ATP + H2O chpt8_files/i0080000.jpg ADP + Pi )
a.
has a chpt8_files/i0080001.jpgG of about -7 kcal/mol under standard conditions.
b.
involves hydrolysis of a terminal phosphate bond of ATP.
c.
can occur spontaneously under appropriate conditions.
d.
Only A and B are correct.
e.
A, B, and C are correct.
 

 8. 

Which of the following is most similar in structure to ATP?
a.
an anabolic steroid
b.
a DNA helix
c.
RNA nucleotides
d.
an amino acid with three phosphate groups attached
e.
a phospholipid
 

 9. 

Which of the following statements is true concerning catabolic pathways?
a.
They combine molecules into more energy-rich molecules.
b.
They are usually coupled with anabolic pathways to which they supply energy in the form of ATP.
c.
They are endergonic.
d.
They are spontaneous and do not need enzyme catalysis.
e.
They build up complex molecules such as protein from simpler compounds.
 

 10. 

Which of the following statements is (are) true about enzyme-catalyzed reactions?
a.
The reaction is faster than the same reaction in the absence of the enzyme.
b.
The free energy change of the reaction is the same as the reaction in the absence of the enzyme.
c.
The reaction always goes in the direction toward chemical equilibrium.
d.
A and B only
e.
A, B, and C
 

 11. 

Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in
a.
bringing glucose and fructose together to form sucrose.
b.
the release of water from sucrose as the bond between glucose and fructose is broken.
c.
breaking the bond between glucose and fructose and forming new bonds from the atoms of water.
d.
production of water from the sugar as bonds are broken between the glucose monomers.
e.
utilization of water as a covalent bond is formed between glucose and fructose to form sucrase.
 

 12. 

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because
a.
the starch solution has less free energy than the sugar solution.
b.
the hydrolysis of starch to sugar is endergonic.
c.
the activation energy barrier for this reaction cannot be surmounted.
d.
starch cannot be hydrolyzed in the presence of so much water.
e.
starch hydrolysis is nonspontaneous.
 

 13. 

Which of the following is not true of enzymes?
a.
Enzyme catalysis is dependent on the pH and temperature of the reaction environment.
b.
Enzyme catalysis is dependent on the three-dimensional structure or conformation of the enzyme.
c.
Enzymes provide activation energy for the reaction they catalyze.
d.
Enzymes are composed primarily of protein, but they may bind nonprotein cofactors.
e.
Enzyme activity can be inhibited if the enzyme's allosteric site is bound with a noncompetitive inhibitor.
 

 14. 

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a chpt8_files/i0150000.jpgG of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the chpt8_files/i0150001.jpgG for the new reaction?
a.
-40 kcal/mol
b.
-20 kcal/mol
c.
0 kcal/mol
d.
+20 kcal/mol
e.
+40 kcal/mol
 
 
Refer to the figure below to answer the following questions.

chpt8_files/i0160000.jpg
 

 15. 

Which curve represents the behavior of an enzyme taken from a bacterium that lives in hot springs at temperatures of 70°C or higher?
a.
curve 1
b.
curve 2
c.
curve 3
d.
curve 4
e.
curve 5
 

 16. 

Which curve was most likely generated from an enzyme that requires a cofactor?
a.
curve 1
b.
curve 2
c.
curve 4
d.
curve 5
e.
It is not possible to determine whether an enzyme requires a cofactor from these data.
 

 17. 

ATP is often an allosteric inhibitor of key enzymes in catabolic pathways. Which of the following statements is inconsistent with the role of ATP?
a.
ATP couples energy production in catabolic pathways to energy demand in anabolic pathways.
b.
When ATP levels are high in the cell, it is an indication that energy supply from catabolic reactions exceeds energy demand by anabolic reactions.
c.
The binding of ATP to allosteric sites on enzymes of the catabolic pathway decreases the production of ATP by the pathway.
d.
Increasing availability of ATP increases the energy available to drive endergonic reactions.
e.
When ATP levels are low in the cell, there is no inhibition of the catabolic pathway and ATP production is at a maximum.
 

 18. 

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
a.
denaturization of the enzyme
b.
allosteric inhibition
c.
competitive inhibition
d.
saturation of the enzyme activity
e.
insufficient cofactors
 

 19. 

Which of the following is true of enzymes?
a.
Enzymes may require a nonprotein cofactor or ion for catalysis to take place.
b.
Enzyme function is reduced if the three-dimensional structure or conformation of an enzyme is altered.
c.
Enzyme function is influenced by physical and chemical environmental factors such as pH and temperature.
d.
Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
e.
All of the above are true of enzymes.
 
 
The following questions are based on the reaction A + B chpt8_files/i0220000.jpg C + D shown in the figure below.

chpt8_files/i0220001.jpg
 

 20. 

Which of the following terms best describes the reaction?
a.
endergonic
b.
exergonic
c.
anabolic
d.
allosteric
e.
nonspontaneous
 

 21. 

Which of the following represents the chpt8_files/i0240000.jpgG of the reaction?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 22. 

Which of the following would be the same in an enzyme-catalyzed or noncatalyzed reaction?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 23. 

Which of the following bests describes the reaction?
a.
negative chpt8_files/i0260000.jpgG, spontaneous
b.
positive chpt8_files/i0260001.jpgG, nonspontaneous
c.
positive chpt8_files/i0260002.jpgG, exergonic
d.
negative chpt8_files/i0260003.jpgG, endergonic
e.
chpt8_files/i0260004.jpgG of zero, chemical equilibrium
 

 24. 

Which of the following represents the difference between the free-energy content of the reaction and the free-energy content of the products?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 25. 

Which of the following represents the activation energy required for the enzyme-catalyzed reaction?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 26. 

Which of the following represents the activation energy required for a noncatalyzed reaction?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 27. 

How does a non-competitive inhibitor decrease the rate of an enzyme reaction?
a.
by binding at the active site of the enzyme
b.
by changing the structure of the enzyme
c.
by changing the free energy change of the reaction
d.
by acting as a coenzyme for the reaction
e.
by decreasing the activation energy of the reaction
 



 
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