CHEM 210 - Module 3: Enzymes and Enzyme Kinetics Exam 2026/2027
UPDATE
1. Which of the following best describes the role of an enzyme in a biological
reaction?
A. It increases the free energy change (ΔG) of the reaction.
B. It increases the activation energy required for the reaction.
C. It decreases the activation energy required for the reaction.
D. It changes the equilibrium constant of the reaction.
Answer: C
Rationale: Enzymes act as catalysts by lowering the activation energy barrier, allowing the
reaction to proceed faster without changing the overall ΔG or equilibrium.
2. A complete, catalytically active enzyme together with its bound coenzyme
and/or metal ions is called a(n):
A. Holoenzyme
B. Apoenzyme
C. Cofactor
D. Prosthetic group
Answer: A
Rationale: A holoenzyme is the active form consisting of the protein component
(apoenzyme) and the necessary non-protein component (cofactor/coenzyme).
,3. Which class of enzymes catalyzes the transfer of electrons from one molecule
to another?
A. Oxidoreductases
B. Hydrolases
C. Transferases
D. Isomerases
Answer: A
Rationale: Oxidoreductases catalyze oxidation-reduction reactions, which involve the
transfer of electrons.
4. The specific region of an enzyme where substrate binding and catalysis occur
is known as the:
A. Allosteric site
B. Regulatory site
C. Binding pocket
D. Active site
Answer: D
Rationale: The active site is the specialized pocket or cleft where the substrate binds and
the chemical reaction takes place.
5. The ‘Induced Fit’ model of enzyme-substrate interaction suggests that:
A. The enzyme changes its conformation upon substrate binding to achieve a tighter fit.
B. The substrate changes shape to fit the enzyme’s rigid active site.
C. The enzyme is a rigid structure that only fits a specific substrate shape.
D. The enzyme and substrate bind through covalent bonds only.
Answer: A
Rationale: The induced fit model states that the enzyme is flexible and undergoes a
conformational change when the substrate binds to optimize the interaction.
, 6. In Michaelis-Menten kinetics, the Michaelis constant (Km) is defined as:
A. The concentration of enzyme required to reach Vmax.
B. The maximum velocity of the reaction.
C. The rate constant for the formation of the ES complex.
D. The substrate concentration at which the reaction velocity is half of Vmax.
Answer: D
Rationale: Km is the substrate concentration [S] at which the initial reaction velocity (Vo)
is exactly one-half of the maximum velocity (Vmax).
7. If an enzyme has a very low Km value for a particular substrate, it implies:
A. Low affinity for the substrate.
B. High affinity for the substrate.
C. The reaction will be very slow.
D. The enzyme is easily inhibited.
Answer: B
Rationale: A low Km indicates that the enzyme reaches half-saturation at a low substrate
concentration, reflecting high binding affinity.
8. On a Lineweaver-Burk plot, the y-intercept represents:
A. 1/Vmax
B. -1/Km
C. Km/Vmax
D. 1/[S]
Answer: A
Rationale: The Lineweaver-Burk equation is 1/Vo = (Km/Vmax)(1/[S]) + 1/Vmax, where
1/Vmax is the y-intercept.
UPDATE
1. Which of the following best describes the role of an enzyme in a biological
reaction?
A. It increases the free energy change (ΔG) of the reaction.
B. It increases the activation energy required for the reaction.
C. It decreases the activation energy required for the reaction.
D. It changes the equilibrium constant of the reaction.
Answer: C
Rationale: Enzymes act as catalysts by lowering the activation energy barrier, allowing the
reaction to proceed faster without changing the overall ΔG or equilibrium.
2. A complete, catalytically active enzyme together with its bound coenzyme
and/or metal ions is called a(n):
A. Holoenzyme
B. Apoenzyme
C. Cofactor
D. Prosthetic group
Answer: A
Rationale: A holoenzyme is the active form consisting of the protein component
(apoenzyme) and the necessary non-protein component (cofactor/coenzyme).
,3. Which class of enzymes catalyzes the transfer of electrons from one molecule
to another?
A. Oxidoreductases
B. Hydrolases
C. Transferases
D. Isomerases
Answer: A
Rationale: Oxidoreductases catalyze oxidation-reduction reactions, which involve the
transfer of electrons.
4. The specific region of an enzyme where substrate binding and catalysis occur
is known as the:
A. Allosteric site
B. Regulatory site
C. Binding pocket
D. Active site
Answer: D
Rationale: The active site is the specialized pocket or cleft where the substrate binds and
the chemical reaction takes place.
5. The ‘Induced Fit’ model of enzyme-substrate interaction suggests that:
A. The enzyme changes its conformation upon substrate binding to achieve a tighter fit.
B. The substrate changes shape to fit the enzyme’s rigid active site.
C. The enzyme is a rigid structure that only fits a specific substrate shape.
D. The enzyme and substrate bind through covalent bonds only.
Answer: A
Rationale: The induced fit model states that the enzyme is flexible and undergoes a
conformational change when the substrate binds to optimize the interaction.
, 6. In Michaelis-Menten kinetics, the Michaelis constant (Km) is defined as:
A. The concentration of enzyme required to reach Vmax.
B. The maximum velocity of the reaction.
C. The rate constant for the formation of the ES complex.
D. The substrate concentration at which the reaction velocity is half of Vmax.
Answer: D
Rationale: Km is the substrate concentration [S] at which the initial reaction velocity (Vo)
is exactly one-half of the maximum velocity (Vmax).
7. If an enzyme has a very low Km value for a particular substrate, it implies:
A. Low affinity for the substrate.
B. High affinity for the substrate.
C. The reaction will be very slow.
D. The enzyme is easily inhibited.
Answer: B
Rationale: A low Km indicates that the enzyme reaches half-saturation at a low substrate
concentration, reflecting high binding affinity.
8. On a Lineweaver-Burk plot, the y-intercept represents:
A. 1/Vmax
B. -1/Km
C. Km/Vmax
D. 1/[S]
Answer: A
Rationale: The Lineweaver-Burk equation is 1/Vo = (Km/Vmax)(1/[S]) + 1/Vmax, where
1/Vmax is the y-intercept.
