CHEM 210 BIOCHEMISTRY MIDTERM
COMPREHENSIVE EXAM QUESTIONS
AND ANSWERS 2026/2027 UPDATE ||
100% GUARANTEED PASS
1. Which of the following amino acids contains a sulfur atom but is incapable of forming
disulfide bridges?
A. Cysteine
B. Threonine
C. Methionine
D. Serine
Answer: C
Conceptual Explanation: Methionine contains a thioether group which is non-reactive for
disulfide formation, unlike the thiol group in Cysteine.
2. In the context of thermodynamics, a reaction is considered spontaneous if:
A. Delta G is positive
B. Delta H is positive
C. Entropy decreases
D. Delta G is negative
,Answer: D
Conceptual Explanation: A negative Gibbs free energy (Delta G) indicates an exergonic
reaction that occurs spontaneously.
3. Which level of protein structure is primarily stabilized by hydrogen bonds between the
carbonyl oxygen and the amide hydrogen of the polypeptide backbone?
A. Primary structure
B. Tertiary structure
C. Secondary structure
D. Quaternary structure
Answer: C
Conceptual Explanation: Secondary structures like alpha-helices and beta-sheets are
formed by backbone hydrogen bonding.
4. Which amino acid lacks a chiral center?
A. Alanine
B. Glycine
C. Proline
D. Valine
Answer: B
, Conceptual Explanation: Glycine’s R-group is a hydrogen atom, making it symmetric and
thus achiral.
5. Using the Henderson-Hasselbalch equation, what is the pH of a solution where the
concentration of the conjugate base is ten times that of the weak acid (pKa = 4.76)?
A. 3.76
B. 4.76
C. 5.76
D. 6.76
Answer: C
Conceptual Explanation: pH = pKa + log([A-]/[HA]). If [A-]/[HA] = 10, then pH = 4.76 +
log(10) = 4.76 + 1 = 5.76.
6. A competitive inhibitor affects an enzyme-catalyzed reaction by:
A. Increasing Km and decreasing Vmax
B. Decreasing Km and keeping Vmax constant
C. Increasing Km and keeping Vmax constant
D. Decreasing both Km and Vmax
Answer: C
COMPREHENSIVE EXAM QUESTIONS
AND ANSWERS 2026/2027 UPDATE ||
100% GUARANTEED PASS
1. Which of the following amino acids contains a sulfur atom but is incapable of forming
disulfide bridges?
A. Cysteine
B. Threonine
C. Methionine
D. Serine
Answer: C
Conceptual Explanation: Methionine contains a thioether group which is non-reactive for
disulfide formation, unlike the thiol group in Cysteine.
2. In the context of thermodynamics, a reaction is considered spontaneous if:
A. Delta G is positive
B. Delta H is positive
C. Entropy decreases
D. Delta G is negative
,Answer: D
Conceptual Explanation: A negative Gibbs free energy (Delta G) indicates an exergonic
reaction that occurs spontaneously.
3. Which level of protein structure is primarily stabilized by hydrogen bonds between the
carbonyl oxygen and the amide hydrogen of the polypeptide backbone?
A. Primary structure
B. Tertiary structure
C. Secondary structure
D. Quaternary structure
Answer: C
Conceptual Explanation: Secondary structures like alpha-helices and beta-sheets are
formed by backbone hydrogen bonding.
4. Which amino acid lacks a chiral center?
A. Alanine
B. Glycine
C. Proline
D. Valine
Answer: B
, Conceptual Explanation: Glycine’s R-group is a hydrogen atom, making it symmetric and
thus achiral.
5. Using the Henderson-Hasselbalch equation, what is the pH of a solution where the
concentration of the conjugate base is ten times that of the weak acid (pKa = 4.76)?
A. 3.76
B. 4.76
C. 5.76
D. 6.76
Answer: C
Conceptual Explanation: pH = pKa + log([A-]/[HA]). If [A-]/[HA] = 10, then pH = 4.76 +
log(10) = 4.76 + 1 = 5.76.
6. A competitive inhibitor affects an enzyme-catalyzed reaction by:
A. Increasing Km and decreasing Vmax
B. Decreasing Km and keeping Vmax constant
C. Increasing Km and keeping Vmax constant
D. Decreasing both Km and Vmax
Answer: C
