Biochemistry Final Exam (CHEM 210) – Cumulative
Questions|Answers|Rationales 2026/2027 update
1. Which of the following amino acids is considered non-chiral?
A. Alanine
B. Proline
C. Valine
D. Glycine
Answer: D
Rationale: Glycine has a hydrogen atom as its R-group, making the alpha-carbon bonded to
two identical hydrogen atoms, thus it lacks a chiral center.
2. In the Michaelis-Menten equation, what does Km represent?
A. The maximum velocity of the reaction
B. The total enzyme concentration
C. The substrate concentration at half of Vmax
D. The turnover number
Answer: C
Rationale: Km is the Michaelis constant, defined as the substrate concentration at which
the reaction rate is half of the maximum velocity (Vmax).
,3. Which stabilizing interaction is most important for the formation of an alpha-
helix?
A. Disulfide bridges
B. Intrachain hydrogen bonds
C. Hydrophobic interactions
D. Ionic bonds
Answer: B
Rationale: The alpha-helix is stabilized by hydrogen bonds between the carbonyl oxygen
of one amino acid and the amino hydrogen of an amino acid four residues down the chain.
4. Which enzyme catalyzes the rate-limiting step of glycolysis?
A. Hexokinase
B. Pyruvate Kinase
C. Aldolase
D. Phosphofructokinase-1 (PFK-1)
Answer: D
Rationale: PFK-1 is the primary regulatory and rate-limiting enzyme in glycolysis,
controlled by ATP and fructose-2,6-bisphosphate levels.
5. During the Citric Acid Cycle (TCA), how many molecules of NADH are
produced per one turn of the cycle?
A. 1
B. 2
C. 4
D. 3
Answer: D
Rationale: One turn of the TCA cycle produces 3 NADH, 1 FADH2, and 1 GTP (or ATP) per
acetyl-CoA molecule.
, 6. What is the primary function of SDS in SDS-PAGE electrophoresis?
A. To visualize the protein bands
B. To act as a buffer solution
C. To denature proteins and give them a uniform negative charge
D. To catalyze the polymerization of the gel
Answer: C
Rationale: Sodium Dodecyl Sulfate (SDS) unfolds proteins and coats them with negative
charges so they migrate through the gel based solely on their molecular weight.
7. Which molecule acts as the final electron acceptor in the electron transport
chain under aerobic conditions?
A. Water
B. NAD+
C. Oxygen (O2)
D. Cytochrome c
Answer: C
Rationale: Oxygen is the terminal electron acceptor in the ETC, where it is reduced to form
water.
8. Which of the following is a characteristic of a competitive inhibitor?
A. It increases the apparent Km
B. It decreases Km
C. It increases Vmax
D. It binds only to the enzyme-substrate complex
Answer: A
Rationale: Competitive inhibitors compete with the substrate for the active site, increasing
the amount of substrate needed to reach 1/2 Vmax (increasing Km) but not changing Vmax.
Questions|Answers|Rationales 2026/2027 update
1. Which of the following amino acids is considered non-chiral?
A. Alanine
B. Proline
C. Valine
D. Glycine
Answer: D
Rationale: Glycine has a hydrogen atom as its R-group, making the alpha-carbon bonded to
two identical hydrogen atoms, thus it lacks a chiral center.
2. In the Michaelis-Menten equation, what does Km represent?
A. The maximum velocity of the reaction
B. The total enzyme concentration
C. The substrate concentration at half of Vmax
D. The turnover number
Answer: C
Rationale: Km is the Michaelis constant, defined as the substrate concentration at which
the reaction rate is half of the maximum velocity (Vmax).
,3. Which stabilizing interaction is most important for the formation of an alpha-
helix?
A. Disulfide bridges
B. Intrachain hydrogen bonds
C. Hydrophobic interactions
D. Ionic bonds
Answer: B
Rationale: The alpha-helix is stabilized by hydrogen bonds between the carbonyl oxygen
of one amino acid and the amino hydrogen of an amino acid four residues down the chain.
4. Which enzyme catalyzes the rate-limiting step of glycolysis?
A. Hexokinase
B. Pyruvate Kinase
C. Aldolase
D. Phosphofructokinase-1 (PFK-1)
Answer: D
Rationale: PFK-1 is the primary regulatory and rate-limiting enzyme in glycolysis,
controlled by ATP and fructose-2,6-bisphosphate levels.
5. During the Citric Acid Cycle (TCA), how many molecules of NADH are
produced per one turn of the cycle?
A. 1
B. 2
C. 4
D. 3
Answer: D
Rationale: One turn of the TCA cycle produces 3 NADH, 1 FADH2, and 1 GTP (or ATP) per
acetyl-CoA molecule.
, 6. What is the primary function of SDS in SDS-PAGE electrophoresis?
A. To visualize the protein bands
B. To act as a buffer solution
C. To denature proteins and give them a uniform negative charge
D. To catalyze the polymerization of the gel
Answer: C
Rationale: Sodium Dodecyl Sulfate (SDS) unfolds proteins and coats them with negative
charges so they migrate through the gel based solely on their molecular weight.
7. Which molecule acts as the final electron acceptor in the electron transport
chain under aerobic conditions?
A. Water
B. NAD+
C. Oxygen (O2)
D. Cytochrome c
Answer: C
Rationale: Oxygen is the terminal electron acceptor in the ETC, where it is reduced to form
water.
8. Which of the following is a characteristic of a competitive inhibitor?
A. It increases the apparent Km
B. It decreases Km
C. It increases Vmax
D. It binds only to the enzyme-substrate complex
Answer: A
Rationale: Competitive inhibitors compete with the substrate for the active site, increasing
the amount of substrate needed to reach 1/2 Vmax (increasing Km) but not changing Vmax.
