Principles of Biochemistry, 5e (Moran/Horton/Scrimgeour) - Test Bank - Chapter 6

Principles of Biochemistry, 5/E



Laurence A. Moran, University of Toronto
Robert A Horton, North Carolina State University
Gray Scrimgeour, University of Toronto
Marc Perry, University of Toronto

ISBN-10: 0321707338
ISBN-13:  9780321707338
Publisher:  Prentice Hall
Copyright:  2012

Principles of Biochemistry, 5e (Moran/Horton/Scrimgeour/Perry/Rawn)
Chapter 6   Mechanisms of Enzymes


1) A detailed description of a chemical reaction in terms of the molecular, atomic or subatomic events is called the reaction ________.
A) mechanism
B) pathway
C) primary sequence
D) motif
Answer:  A
Page Ref: Section 6-1

2) Which mode(s) of catalysis is/are classified as chemical effects?
1.   Transition state stabilization
2.   Acid-base catalysis
3.   Covalent catalysis
4.   Proximity effect
A) 3 only.
B) 1, 2 and 3.
C) 2 and 3.
D) All of them.
Answer:  C
Page Ref: Section 6-1

3) How is the half-reaction Cu2+ + 2e- ? Cu classified?
A) Free radical reaction.
B) Electrophilic substitution reaction.
C) Oxidation reaction.
D) Reduction reaction.
E) None of the above.
Answer:  D
Page Ref: Section 6-1

4) In the reaction below, Y- is ________.

Y- + CH2X ? CH2Y + X-
A) the leaving group
B) the attacking electrophile
C) the reaction intermediate
D) a nucleophile
Answer:  D
Page Ref: Section 6-1

 
5) Which represents a hydride ion?
A) H2-
B) H-
C) H+
D) H3O+
Answer:  B
Page Ref: Section 6-1
6) The movement of ________ is key to understanding chemical and enzymatic reactions.
A) neutrons
B) electrons
C) nucleophiles
D) electrophiles
Answer:  B
Page Ref: Section 6-1

7) A chemical group that has a negative charge or an unshared electron pair may act as a(n)
A) transition state.
B) neutrophile.
C) electrophile.
D) nucleophile.
Answer:  D
Page Ref: Section 6-1

8) Cleavage of a C-C bond produces a carbanion that ________ both electrons and a carbocation that ________ both electrons.
A) loses; loses
B) loses; keeps
C) keeps; loses
D) keeps; keeps
Answer:  C
Page Ref: Section 6-1

9) In the following chemical reaction which species is the reducing agent?

CH4 + 2 O2 ? CO2 + 2 H2O
A) CH4
B) O2
C) CO2
D) H2O
E) None of the above, this is not an oxidation-reduction reaction.
Answer:  A
Page Ref: Section 6-1

 
10) In this reaction, the carbon is ________.

 
A) oxidized
B) reduced
C) neutralized
D) hydrolyzed
Answer:  B
Page Ref: Section 6-1
11) Which statement does not apply to transition states?
A) Many have been detected experimentally.
B) Chemical bonds are in the process of being formed and broken.
C) Have lifetimes on the order of 10-14 to 10-13 seconds.
D) Differ in energy from the ground state by the activation energy.
Answer:  A
Page Ref: Section 6-2

12) On the energy diagram below, which point represents a transition state?

 
A) Point 1
B) Point 2
C) Point 3
D) Point 4
Answer:  C
Page Ref: Section 6-2

13) Which will be different for a catalyzed reaction versus an uncatalyzed reaction?
A) Activation energy.
B) Ground state energy.
C) Free energy change.
D) All of the above.
Answer:  A
Page Ref: Section 6-2
14) On the energy diagram below, which point represents an intermediate?

 
A) Point 1
B) Point 2
C) Point 3
D) Point 4
Answer:  B
Page Ref: Section 6-2

15) On the energy diagram below, which arrow(s) represent the activation energy for the forward and reverse reactions?
 
A) Arrow 1 is the activation energy for both the forward and reverse reactions.
B) Arrow 1 is the activation energy for the forward reaction and arrow 2 is the activation energy for the reverse reaction.
C) Arrow 1 is the activation energy for the forward reaction and arrow 3 is the activation energy for the reverse reaction.
D) Arrow 3 is the activation energy for the forward reaction and arrow 2 is the activation energy for the reverse reaction.
Answer:  B
Page Ref: Section 6-2

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