BIOCHEM 210 COMPREHENSIVE EXAM
(MODULES 1-8) EXAM QUESTIONS AND
ANSWERS
1. Which property of water allows it to act as an efficient solvent for crystalline salts like
NaCl?
A. High dielectric constant
B. High surface tension
C. Low boiling point
D. Non-polar nature
Answer: A
Conceptual Explanation: Water’s high dielectric constant allows it to effectively screen
the electrostatic interactions between ions, facilitating their dissolution.
2. Which amino acid is considered a ‘helix breaker’ due to its rigid cyclic structure?
A. Glycine
B. Proline
C. Alanine
D. Leucine
,Answer: B
Conceptual Explanation: Proline’s cyclic side chain restricts its phi angle and lacks a
hydrogen atom on its nitrogen for hydrogen bonding, destabilizing alpha-helices.
3. In the Henderson-Hasselbalch equation, what happens when the pH equals the pKa?
A. The acid is fully protonated
B. The solution is at its maximum acidity
C. The concentration of acid equals the concentration of conjugate base
D. The buffer capacity is zero
Answer: C
Conceptual Explanation: When pH = pKa, the log([A-]/[HA]) term is zero, meaning [A-] =
[HA].
4. Which level of protein structure is primarily stabilized by hydrogen bonds between the
backbone carbonyl oxygens and amide nitrogens?
A. Secondary structure
B. Primary structure
C. Tertiary structure
D. Quaternary structure
Answer: A
, Conceptual Explanation: Secondary structures like alpha-helices and beta-sheets are
formed by hydrogen bonding patterns in the polypeptide backbone.
5. According to the Bohr effect, how does a decrease in pH affect hemoglobin’s affinity for
oxygen?
A. Affinity increases, shifting the curve to the left
B. Oxygen binding becomes non-cooperative
C. Affinity remains unchanged
D. Affinity decreases, shifting the curve to the right
Answer: D
Conceptual Explanation: Lower pH (higher H+ concentration) stabilizes the T-state of
hemoglobin, decreasing its affinity for O2 and promoting its release to tissues.
6. What is the primary role of 2,3-bisphosphoglycerate (2,3-BPG) in red blood cells?
A. To increase hemoglobin’s affinity for oxygen
B. To stabilize the T-state of hemoglobin
C. To catalyze the conversion of CO2 to bicarbonate
D. To act as an intermediate in glycolysis
Answer: B
Conceptual Explanation: 2,3-BPG binds to the central cavity of the hemoglobin tetramer,
stabilizing the T-state and facilitating oxygen unloading.
(MODULES 1-8) EXAM QUESTIONS AND
ANSWERS
1. Which property of water allows it to act as an efficient solvent for crystalline salts like
NaCl?
A. High dielectric constant
B. High surface tension
C. Low boiling point
D. Non-polar nature
Answer: A
Conceptual Explanation: Water’s high dielectric constant allows it to effectively screen
the electrostatic interactions between ions, facilitating their dissolution.
2. Which amino acid is considered a ‘helix breaker’ due to its rigid cyclic structure?
A. Glycine
B. Proline
C. Alanine
D. Leucine
,Answer: B
Conceptual Explanation: Proline’s cyclic side chain restricts its phi angle and lacks a
hydrogen atom on its nitrogen for hydrogen bonding, destabilizing alpha-helices.
3. In the Henderson-Hasselbalch equation, what happens when the pH equals the pKa?
A. The acid is fully protonated
B. The solution is at its maximum acidity
C. The concentration of acid equals the concentration of conjugate base
D. The buffer capacity is zero
Answer: C
Conceptual Explanation: When pH = pKa, the log([A-]/[HA]) term is zero, meaning [A-] =
[HA].
4. Which level of protein structure is primarily stabilized by hydrogen bonds between the
backbone carbonyl oxygens and amide nitrogens?
A. Secondary structure
B. Primary structure
C. Tertiary structure
D. Quaternary structure
Answer: A
, Conceptual Explanation: Secondary structures like alpha-helices and beta-sheets are
formed by hydrogen bonding patterns in the polypeptide backbone.
5. According to the Bohr effect, how does a decrease in pH affect hemoglobin’s affinity for
oxygen?
A. Affinity increases, shifting the curve to the left
B. Oxygen binding becomes non-cooperative
C. Affinity remains unchanged
D. Affinity decreases, shifting the curve to the right
Answer: D
Conceptual Explanation: Lower pH (higher H+ concentration) stabilizes the T-state of
hemoglobin, decreasing its affinity for O2 and promoting its release to tissues.
6. What is the primary role of 2,3-bisphosphoglycerate (2,3-BPG) in red blood cells?
A. To increase hemoglobin’s affinity for oxygen
B. To stabilize the T-state of hemoglobin
C. To catalyze the conversion of CO2 to bicarbonate
D. To act as an intermediate in glycolysis
Answer: B
Conceptual Explanation: 2,3-BPG binds to the central cavity of the hemoglobin tetramer,
stabilizing the T-state and facilitating oxygen unloading.
