BioChem 210 Comprehensive Final Exam 2026 Questions and Answers
100% PASS
1. Which of the following describes the Henderson-Hasselbalch equation?
A. pH = pKa - log([A-]/[HA])
B. pH = pKa + log([A-]/[HA])
C. pKa = pH + log([HA]/[A-])
D. pH = pKa * log([A-]/[HA])
Answer: B
Rationale: The Henderson-Hasselbalch equation relates pH, pKa, and the ratio of conjugate
base to weak acid concentration.
2. What is the primary characteristic of an amphipathic molecule?
A. It is entirely hydrophobic
B. It is entirely hydrophilic
C. It contains both hydrophilic and hydrophobic regions
D. It contains only non-polar covalent bonds
Answer: C
Rationale: Amphipathic molecules, like phospholipids, have both polar (hydrophilic) and
non-polar (hydrophobic) parts.
3. Which amino acid is classified as non-polar and aliphatic?
A. Lysine
B. Glutamate
C. Serine
D. Leucine
Answer: D
,Rationale: Leucine is a non-polar amino acid with an aliphatic side chain; Lysine is basic,
Serine is polar uncharged, and Glutamate is acidic.
4. At a pH below its pI, an amino acid will have what net charge?
A. Negative
B. Positive
C. Neutral
D. Zero
Answer: B
Rationale: When pH is lower than the isoelectric point (pI), the amino acid is in an acidic
environment and becomes protonated, resulting in a net positive charge.
5. What type of bond stabilizes the primary structure of a protein?
A. Hydrogen bonds
B. Ionic bonds
C. Disulfide bridges
D. Peptide bonds
Answer: D
Rationale: The primary structure is the linear sequence of amino acids held together by
covalent peptide bonds.
6. Which secondary structure is characterized by a right-handed coil stabilized
by intrachain hydrogen bonds?
A. Beta-pleated sheet
B. Random coil
C. Beta-turn
D. Alpha-helix
Answer: D
Rationale: The alpha-helix is a common secondary structure motif stabilized by hydrogen
bonds between the carbonyl oxygen and amide hydrogen four residues apart.
, 7. In enzyme kinetics, what does the Km (Michaelis constant) represent?
A. The maximum velocity of the reaction
B. The substrate concentration at half Vmax
C. The total concentration of enzyme
D. The equilibrium constant of the reaction
Answer: B
Rationale: Km is the substrate concentration at which the reaction rate is half of its
maximum velocity (Vmax).
8. How does a competitive inhibitor affect enzyme kinetics?
A. Increases Km and decreases Vmax
B. Decreases Km and leaves Vmax unchanged
C. Leaves Km unchanged and decreases Vmax
D. Increases Km and leaves Vmax unchanged
Answer: D
Rationale: Competitive inhibitors compete for the active site, increasing the amount of
substrate needed to reach half Vmax (higher Km) but not affecting the maximum rate
(Vmax).
9. Which molecule is a common ketose sugar?
A. Glucose
B. Fructose
C. Galactose
D. Mannose
Answer: B
Rationale: Fructose is a ketohexose, while glucose, galactose, and mannose are
aldohexoses.
100% PASS
1. Which of the following describes the Henderson-Hasselbalch equation?
A. pH = pKa - log([A-]/[HA])
B. pH = pKa + log([A-]/[HA])
C. pKa = pH + log([HA]/[A-])
D. pH = pKa * log([A-]/[HA])
Answer: B
Rationale: The Henderson-Hasselbalch equation relates pH, pKa, and the ratio of conjugate
base to weak acid concentration.
2. What is the primary characteristic of an amphipathic molecule?
A. It is entirely hydrophobic
B. It is entirely hydrophilic
C. It contains both hydrophilic and hydrophobic regions
D. It contains only non-polar covalent bonds
Answer: C
Rationale: Amphipathic molecules, like phospholipids, have both polar (hydrophilic) and
non-polar (hydrophobic) parts.
3. Which amino acid is classified as non-polar and aliphatic?
A. Lysine
B. Glutamate
C. Serine
D. Leucine
Answer: D
,Rationale: Leucine is a non-polar amino acid with an aliphatic side chain; Lysine is basic,
Serine is polar uncharged, and Glutamate is acidic.
4. At a pH below its pI, an amino acid will have what net charge?
A. Negative
B. Positive
C. Neutral
D. Zero
Answer: B
Rationale: When pH is lower than the isoelectric point (pI), the amino acid is in an acidic
environment and becomes protonated, resulting in a net positive charge.
5. What type of bond stabilizes the primary structure of a protein?
A. Hydrogen bonds
B. Ionic bonds
C. Disulfide bridges
D. Peptide bonds
Answer: D
Rationale: The primary structure is the linear sequence of amino acids held together by
covalent peptide bonds.
6. Which secondary structure is characterized by a right-handed coil stabilized
by intrachain hydrogen bonds?
A. Beta-pleated sheet
B. Random coil
C. Beta-turn
D. Alpha-helix
Answer: D
Rationale: The alpha-helix is a common secondary structure motif stabilized by hydrogen
bonds between the carbonyl oxygen and amide hydrogen four residues apart.
, 7. In enzyme kinetics, what does the Km (Michaelis constant) represent?
A. The maximum velocity of the reaction
B. The substrate concentration at half Vmax
C. The total concentration of enzyme
D. The equilibrium constant of the reaction
Answer: B
Rationale: Km is the substrate concentration at which the reaction rate is half of its
maximum velocity (Vmax).
8. How does a competitive inhibitor affect enzyme kinetics?
A. Increases Km and decreases Vmax
B. Decreases Km and leaves Vmax unchanged
C. Leaves Km unchanged and decreases Vmax
D. Increases Km and leaves Vmax unchanged
Answer: D
Rationale: Competitive inhibitors compete for the active site, increasing the amount of
substrate needed to reach half Vmax (higher Km) but not affecting the maximum rate
(Vmax).
9. Which molecule is a common ketose sugar?
A. Glucose
B. Fructose
C. Galactose
D. Mannose
Answer: B
Rationale: Fructose is a ketohexose, while glucose, galactose, and mannose are
aldohexoses.
