QUIZ #2 Thermodynamics and Kinetics
32.
You are given the reaction A -> B, where delta-G= = -48cal/mol. If you perform this reaction starting
with 100x more [B] than [A], the actual free energy change (delta-G) for the reaction would be:
a. More A+@ than the delta-G=
b. More A-A than the delta-G=
c. The same as the delta-G=
d. Cannot be determined from the information given
33.
A solution of reactants and products is at equilibrium when:
a. delta G= = 0
b. delta H < delta S
c. The energy of the reactants and products are equal
d. The concentration of reactants and products are equal
e. More product than reactant is present at the end of the reaction
34.
What is the approximate Keq of a reaction when a 1 mol/liter solution of an ester is hydrolyzed by
water?
a. 0
b. 1
c. 158
d. 1364
e. The Keq cannot be estimated from the given information
35.
What factor(s) prevent the formation of phosphoenol pyruvate from a mixture of phosphate and
pyruvate?
a. Resonance stabilization of phosphate
b. Ketoenol tautomerism exhibited by pyruvate
c. Hydrogen bonding between water and inorganic phosphate
d. Hydrophobic repulsion of phosphate and pyruvate
e. Both 1) and 2) are correct
36.
A comparison of carbohydrates and lipids (on a carbon for carbon basis) reveals that carbohydrates:
a. Have more energy than lipids because the carbohydrates are more reduced
b. Have less energy than lipids because the lipids are more reduced
c. Have equivalent amounts of energy if their number of carbon atoms are the same
d. Have smaller molecular weights than lipids
e. Taste better than lipids
37.
Which bond's hydrolysis results in the greatest energy release per mole?
a. Thiol-esters
b. Anhydrides
c. Esters
d. Sulfoesters
e. Amides
38.
A cold-pack, administered in the case of a minor sports injury becomes cold when its contents are
mixed. The reaction occurring within the pack has:
a. a delta H that is negative
b. a delta S that is negative
c. Both 1) and 2) must be true
d. Neither 1) nor 2) must be true
39.
For reaction X --> Y to be spontaneous, what conditions must be satisfied?
a. [X] must be initially greater than [Y]
b. [Y] must be greater than [X] at equilibrium
c. delta-G < 0
d. delta-G > 0
e. delta-G = 0
40.
How does the Keq of a reaction compare to the Keq of the reverse reaction?
a. They are the same because the reactants and the products are the same.
b. They are the same but the reaction kinetics are different.
c. The Keq of the reverse reaction is equal to (-) Keq of the forward reaction.
d. The Keq of the reverse reaction is equal to the reciprocal of the Keq for the forward reaction.
e. The two Keq=s have no relationship because they catalyze different reactions.
41.
If the keq for the reaction below is 20/1, what is the delta-G= for DHAP --> G-3-P?
G-3-P --> DHAP
a. - 1.77 kcal / mol
b. +1.77 kcal / mol
c. +4.33 kcal / mol
d. +7 kcal / mol
42.
Which of the following is NOT true of enzymes?
a. Enzymes lower the energy barrier for a reaction
b. Enzymes assist in making a reaction more spontaneous
c. Enzymes increase the rate of a reaction
d. The enzyme concentration affects the Vmax but not the Km of a reaction
e. Enzymes are biological catalysts
43.
The Km of an enzyme catalyzed reaction refers to:
a. The affinity between the substrate and its enzyme
b. The rate of turnover of the E-S complex to an E-P complex
c. The amount of [S] required to reach 2 Vmax
d. The velocity of the reaction when the enzyme is 2 saturated
44.
Concerning Km, which of the following is TRUE?
a. Km = inverse of affinity between E and S
b. Km = 2 Vmax
c. Km is not altered when [E] is increased
d. The higher the Km, the slower the velocity
e. All of the above are true
45.
In comparing the specificity of enzymes for their substrates, one should compare their respective:
a. Vmax
b. Km
c. TN
d. Vmax/Km
e. Vmax/TN
46.
A non-competitive inhibitor:
a. Alters the Vmax
b. Alters the Km
c. Both 1) and 2) are correct
d. Neither 1) nor 2) are correct
47.
Which of the following terms represent the affinity of an enzyme for its substrate?
a. k1/k2
b. (k2 + k3)/k1
c. [E][S]/[ES]
d. k2/k3
e. k3 x [ES]
48.
The Km of an enzyme takes into account:
a. The affinity of an enzyme for its substrate
b. The enzyme's turnover rate
c. Both 1) and 2) are correct
d. Neither 1) nor 2) are correct
49.
An amino acid substitution is made in an enzyme which causes the enzyme's Vmax to increase. This
change might also cause ____ in the enzyme's Km.
a. An increase
b. A decrease
c. No change
d. All of the above are possible
50.
The following family of lines is produced by which kind of inhibitor?
a. Competitive
b. Uncompetitive
c. Non-competitive
d. Irreversible
e. Allosteric
51.
If the enzyme concentration in the following V vs [S] plot were to be decreased by 50%, at what location
on the graph will the Anew Km@ be found?
a. A
b. B
c. C
d. D
e. E
52.
What type of enzymatic inhibitor changes Vmax but not Km?
a. Uncompetitive
b. Noncompetitive
c. Competitive
d. Irreversible
e. Both 2) and 4) are correct
53.
What class of enzymes uses NADP+ a cofactor?
a. Lyases
b. Hydrolases
c. Isomerases
d. Transferases
e. Oxidoreductases
54.
What class of enzyme will catalyze the following reaction?
PPi --> 2Pi
a. Phosphatase
b. Pyrophosphatase
c. Pyrophosphorylase
d. Phosphorylase
e. Kinase
55.
Which of the following have an effect on the Vmax of a reaction?
a. Temperature
b. Concentration of enzyme
c. pH
d. Concentration of substrate
e. All of the above are correct
f. All but one of the above are correct
56.
What is "v" when [S] = 5Km?
a. 50% of Vmax
b. 66% of Vmax
c. 75% of Vmax
d. 83% of Vmax
e. 90% of Vmax
f. 100% of Vmax
57.
In Michaelis-Menton enzyme kinetics, v = 2 Vmax when:
a. [S] = Km
b. [S] = 2 Km
c. [S] = 5 Km
d. [S] = 10 Km
e. None of the above
58.
The mechanism for the hydrolysis of polysaccharides in the cell wall of bacteria by lysozyme involves:
a. Acid-base catalysis
b. Covalent catalysis
c. The serine protease mechanism
d. A carbonium ion intermediate
e. Both 1) and 4) are correct
59.
Which class of enzyme catalyzes the following reaction?
glucose-6-PO4 --> glucose-1-PO4
a. Kinase
b. Phosphatase
c. Phosphorylase
d. Mutase
e. Transferase
60.
The reason that Km is not equal to the inverse of the affinity between an enzyme and its substrate is:
a. Km = 2 Vmax
b. Vmax = k3 [ES]
c. v = Vmax [S]/Km + [S]
d. Km = (k2 + k3)/k1
e. None of the above are correct because Km is the inverse of the affinity between E and S
61.
On the following Lineweaver-Burk plot of a system with various inhibitors, which line represents the
situation when no inhibitor is present?
a. a
b. b
c. c
d. d
62.
In the derivation of the Michaelis-Menton equation, which reaction was assumed to be the rate limiting
step?
a. k1
b. k2
c. k3
d. k4
e. None of the reactions were assumed to be rate limiting
63.
Which of the following reactions increases linearly with the concentration of its substrate(s)?
a. First-order
b. Pseudo-first order
c. Second-order
d. Zero order
e. Mixed: first and zero order