BIOCHEM 210 COMPREHENSIVE FINAL
EXAM (MODULES 1-8) QUESTIONS
WITH VERIFIED ANSWERS
1. Which of the following amino acids has a side chain with a pKa close to physiological pH,
making it frequently involved in acid-base catalysis in enzyme active sites?
A. Lysine
B. Histidine
C. Arginine
D. Aspartate
Answer: B
Conceptual Explanation: Histidine has an imidazole side chain with a pKa of
approximately 6.0, allowing it to act as both a proton donor and acceptor at physiological
pH.
2. In the context of the hydrophobic effect, what is the primary thermodynamic driving force
for the folding of globular proteins?
A. Decrease in enthalpy due to hydrogen bonding
B. Decrease in protein entropy
,C. Increase in solvent entropy
D. Increase in enthalpy due to van der Waals forces
Answer: C
Conceptual Explanation: The burial of nonpolar side chains releases ordered water
molecules (clathrates) back into the bulk solvent, significantly increasing the entropy of the
system.
3. An enzyme follows Michaelis-Menten kinetics. If the concentration of substrate is equal to
3 times the Km, what is the initial velocity (v0) relative to Vmax?
A. 0.25 Vmax
B. 0.50 Vmax
C. 0.90 Vmax
D. 0.75 Vmax
Answer: D
Conceptual Explanation: Using v0 = Vmax[S] / (Km + [S]), substituting [S] = 3Km gives v0
= Vmax(3Km) / (4Km) = 0.75 Vmax.
4. Competitive inhibitors change which kinetic parameters in a Lineweaver-Burk plot?
A. Increase the y-intercept, no change in slope
B. Decrease the x-intercept, increase the slope
C. Increase the x-intercept, no change in slope
, D. No change in the y-intercept, increase the slope
Answer: D
Conceptual Explanation: Competitive inhibitors increase the apparent Km (moving the x-
intercept toward zero) but do not change Vmax (y-intercept remains constant), thus
increasing the slope (Km/Vmax).
5. The Bohr effect describes the decrease in hemoglobin’s affinity for oxygen in the presence
of which factors?
A. High pH and low CO2
B. Low pH and low 2,3-BPG
C. Low pH and high CO2
D. High pH and high 2,3-BPG
Answer: C
Conceptual Explanation: Low pH (high H+) and high CO2 promote the T-state (tense
state) of hemoglobin, facilitating oxygen release in metabolically active tissues.
6. Which of the following sugars is a non-reducing disaccharide?
A. Lactose
B. Maltose
C. Cellobiose
D. Sucrose
EXAM (MODULES 1-8) QUESTIONS
WITH VERIFIED ANSWERS
1. Which of the following amino acids has a side chain with a pKa close to physiological pH,
making it frequently involved in acid-base catalysis in enzyme active sites?
A. Lysine
B. Histidine
C. Arginine
D. Aspartate
Answer: B
Conceptual Explanation: Histidine has an imidazole side chain with a pKa of
approximately 6.0, allowing it to act as both a proton donor and acceptor at physiological
pH.
2. In the context of the hydrophobic effect, what is the primary thermodynamic driving force
for the folding of globular proteins?
A. Decrease in enthalpy due to hydrogen bonding
B. Decrease in protein entropy
,C. Increase in solvent entropy
D. Increase in enthalpy due to van der Waals forces
Answer: C
Conceptual Explanation: The burial of nonpolar side chains releases ordered water
molecules (clathrates) back into the bulk solvent, significantly increasing the entropy of the
system.
3. An enzyme follows Michaelis-Menten kinetics. If the concentration of substrate is equal to
3 times the Km, what is the initial velocity (v0) relative to Vmax?
A. 0.25 Vmax
B. 0.50 Vmax
C. 0.90 Vmax
D. 0.75 Vmax
Answer: D
Conceptual Explanation: Using v0 = Vmax[S] / (Km + [S]), substituting [S] = 3Km gives v0
= Vmax(3Km) / (4Km) = 0.75 Vmax.
4. Competitive inhibitors change which kinetic parameters in a Lineweaver-Burk plot?
A. Increase the y-intercept, no change in slope
B. Decrease the x-intercept, increase the slope
C. Increase the x-intercept, no change in slope
, D. No change in the y-intercept, increase the slope
Answer: D
Conceptual Explanation: Competitive inhibitors increase the apparent Km (moving the x-
intercept toward zero) but do not change Vmax (y-intercept remains constant), thus
increasing the slope (Km/Vmax).
5. The Bohr effect describes the decrease in hemoglobin’s affinity for oxygen in the presence
of which factors?
A. High pH and low CO2
B. Low pH and low 2,3-BPG
C. Low pH and high CO2
D. High pH and high 2,3-BPG
Answer: C
Conceptual Explanation: Low pH (high H+) and high CO2 promote the T-state (tense
state) of hemoglobin, facilitating oxygen release in metabolically active tissues.
6. Which of the following sugars is a non-reducing disaccharide?
A. Lactose
B. Maltose
C. Cellobiose
D. Sucrose
