BIOCHEMISTRY CHEM 210
COMPREHENSIVE MASTERY EXAM
(MODULES 1-8) QUESTIONS AND
ANSWERS 2026/2027 UPDATE || 100%
GUARANTEED PASS
1. Which of the following conditions would lead to the most significant decrease in the
fluidity of a biological membrane?
A. Increase in the temperature of the environment.
B. Increase in the concentration of unsaturated fatty acids.
C. Decrease in the average chain length of fatty acid tails.
D. Increase in the proportion of long-chain saturated fatty acids.
Answer: D
Conceptual Explanation: Long-chain saturated fatty acids have higher melting points and
pack more tightly due to Van der Waals forces, decreasing membrane fluidity compared to
unsaturated or short-chain fatty acids.
2. In the titration of a weak acid with a strong base, at what point is the pH equal to the pKa?
A. At the equivalence point.
,B. When the acid is completely dissociated.
C. At the beginning of the titration.
D. At the half-equivalence point.
Answer: D
Conceptual Explanation: According to the Henderson-Hasselbalch equation, when [A-] =
[HA] (half-equivalence point), the log([A-]/[HA]) term becomes zero, making pH = pKa.
3. A reaction has a Delta H of -50 kJ/mol and a Delta S of -200 J/mol K. At what temperature
range is this reaction spontaneous?
A. Temperatures above 250 K
B. Temperatures below 250 K
C. All temperatures
D. The reaction is never spontaneous
Answer: B
Conceptual Explanation: For spontaneity, Delta G = Delta H - T(Delta S) < 0. Setting -
50,000 - T(-200) < 0 gives 200T < 50,000, so T < 250 K.
4. Which amino acid contains a sulfur atom but cannot form disulfide bridges?
A. Cysteine
B. Serine
, C. Methionine
D. Threonine
Answer: C
Conceptual Explanation: Methionine contains sulfur in a thioether linkage, which is not
reactive enough to form disulfide bonds, unlike the thiol group in Cysteine.
5. Calculate the approximate isoelectric point (pI) of Glutamic Acid (pKa1=2.19, pKa2=9.67,
pKaR=4.25).
A. 5.93
B. 6.96
C. 3.22
D. 7.00
Answer: C
Conceptual Explanation: For acidic amino acids, pI is the average of the two lowest pKa
values: (2.19 + 4.25) / 2 = 3.22.
6. Which level of protein structure is primarily stabilized by hydrogen bonds between
carbonyl oxygens and amide hydrogens of the polypeptide backbone?
A. Secondary
B. Primary
C. Tertiary
COMPREHENSIVE MASTERY EXAM
(MODULES 1-8) QUESTIONS AND
ANSWERS 2026/2027 UPDATE || 100%
GUARANTEED PASS
1. Which of the following conditions would lead to the most significant decrease in the
fluidity of a biological membrane?
A. Increase in the temperature of the environment.
B. Increase in the concentration of unsaturated fatty acids.
C. Decrease in the average chain length of fatty acid tails.
D. Increase in the proportion of long-chain saturated fatty acids.
Answer: D
Conceptual Explanation: Long-chain saturated fatty acids have higher melting points and
pack more tightly due to Van der Waals forces, decreasing membrane fluidity compared to
unsaturated or short-chain fatty acids.
2. In the titration of a weak acid with a strong base, at what point is the pH equal to the pKa?
A. At the equivalence point.
,B. When the acid is completely dissociated.
C. At the beginning of the titration.
D. At the half-equivalence point.
Answer: D
Conceptual Explanation: According to the Henderson-Hasselbalch equation, when [A-] =
[HA] (half-equivalence point), the log([A-]/[HA]) term becomes zero, making pH = pKa.
3. A reaction has a Delta H of -50 kJ/mol and a Delta S of -200 J/mol K. At what temperature
range is this reaction spontaneous?
A. Temperatures above 250 K
B. Temperatures below 250 K
C. All temperatures
D. The reaction is never spontaneous
Answer: B
Conceptual Explanation: For spontaneity, Delta G = Delta H - T(Delta S) < 0. Setting -
50,000 - T(-200) < 0 gives 200T < 50,000, so T < 250 K.
4. Which amino acid contains a sulfur atom but cannot form disulfide bridges?
A. Cysteine
B. Serine
, C. Methionine
D. Threonine
Answer: C
Conceptual Explanation: Methionine contains sulfur in a thioether linkage, which is not
reactive enough to form disulfide bonds, unlike the thiol group in Cysteine.
5. Calculate the approximate isoelectric point (pI) of Glutamic Acid (pKa1=2.19, pKa2=9.67,
pKaR=4.25).
A. 5.93
B. 6.96
C. 3.22
D. 7.00
Answer: C
Conceptual Explanation: For acidic amino acids, pI is the average of the two lowest pKa
values: (2.19 + 4.25) / 2 = 3.22.
6. Which level of protein structure is primarily stabilized by hydrogen bonds between
carbonyl oxygens and amide hydrogens of the polypeptide backbone?
A. Secondary
B. Primary
C. Tertiary
