Biochemistry C785 Final Exam Practice 2026 |WGU
1. Which of the following describes the Bohr effect?
A. As pH increases, hemoglobin’s affinity for oxygen increases
B. As pH decreases, hemoglobin’s affinity for oxygen increases
C. As carbon dioxide increases, hemoglobin’s affinity for oxygen increases
D. As pH decreases, hemoglobin’s affinity for oxygen decreases
Answer: D
Rationale: The Bohr effect states that hemoglobin’s oxygen binding affinity is inversely
related both to acidity and to the concentration of carbon dioxide.
2. Which level of protein structure is defined by the sequence of amino acids
linked by peptide bonds?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Answer: A
Rationale: The primary structure is the linear sequence of amino acids in a polypeptide
chain.
,3. In an enzyme-catalyzed reaction, what happens to the Michaelis constant
(Km) in the presence of a competitive inhibitor?
A. It decreases
B. It remains the same
C. It increases
D. It becomes zero
Answer: C
Rationale: Competitive inhibitors compete with the substrate for the active site, effectively
increasing the amount of substrate needed to reach half of Vmax, thus increasing Km.
4. Which molecule serves as the primary high-energy electron carrier in
glycolysis?
A. FADH2
B. NADPH
C. NADH
D. ATP
Answer: C
Rationale: NAD+ is reduced to NADH during glycolysis as it accepts high-energy electrons
from glucose breakdown.
5. What is the net yield of ATP from one molecule of glucose during glycolysis?
A. 1 ATP
B. 2 ATP
C. 4 ATP
D. 36 ATP
Answer: B
Rationale: Glycolysis produces 4 ATP but consumes 2 ATP in the initial stages, resulting in
a net yield of 2 ATP.
, 6. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between nitrogenous bases to separate the
DNA strands.
7. In the bicarbonate buffer system, what happens when blood pH becomes too
acidic?
A. Bicarbonate reacts with H+ to form carbonic acid
B. Carbonic acid dissociates into bicarbonate and H+
C. The lungs decrease the rate of CO2 exhalation
D. The kidneys excrete more bicarbonate
Answer: A
Rationale: To neutralize excess H+ ions, bicarbonate ions (HCO3-) combine with them to
form carbonic acid (H2CO3), which then converts to CO2 and water.
8. Which type of mutation results in a premature stop codon?
A. Silent mutation
B. Missense mutation
C. Frameshift mutation
D. Nonsense mutation
Answer: D
Rationale: A nonsense mutation is a point mutation that changes a codon for an amino acid
into a stop codon.
1. Which of the following describes the Bohr effect?
A. As pH increases, hemoglobin’s affinity for oxygen increases
B. As pH decreases, hemoglobin’s affinity for oxygen increases
C. As carbon dioxide increases, hemoglobin’s affinity for oxygen increases
D. As pH decreases, hemoglobin’s affinity for oxygen decreases
Answer: D
Rationale: The Bohr effect states that hemoglobin’s oxygen binding affinity is inversely
related both to acidity and to the concentration of carbon dioxide.
2. Which level of protein structure is defined by the sequence of amino acids
linked by peptide bonds?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Answer: A
Rationale: The primary structure is the linear sequence of amino acids in a polypeptide
chain.
,3. In an enzyme-catalyzed reaction, what happens to the Michaelis constant
(Km) in the presence of a competitive inhibitor?
A. It decreases
B. It remains the same
C. It increases
D. It becomes zero
Answer: C
Rationale: Competitive inhibitors compete with the substrate for the active site, effectively
increasing the amount of substrate needed to reach half of Vmax, thus increasing Km.
4. Which molecule serves as the primary high-energy electron carrier in
glycolysis?
A. FADH2
B. NADPH
C. NADH
D. ATP
Answer: C
Rationale: NAD+ is reduced to NADH during glycolysis as it accepts high-energy electrons
from glucose breakdown.
5. What is the net yield of ATP from one molecule of glucose during glycolysis?
A. 1 ATP
B. 2 ATP
C. 4 ATP
D. 36 ATP
Answer: B
Rationale: Glycolysis produces 4 ATP but consumes 2 ATP in the initial stages, resulting in
a net yield of 2 ATP.
, 6. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between nitrogenous bases to separate the
DNA strands.
7. In the bicarbonate buffer system, what happens when blood pH becomes too
acidic?
A. Bicarbonate reacts with H+ to form carbonic acid
B. Carbonic acid dissociates into bicarbonate and H+
C. The lungs decrease the rate of CO2 exhalation
D. The kidneys excrete more bicarbonate
Answer: A
Rationale: To neutralize excess H+ ions, bicarbonate ions (HCO3-) combine with them to
form carbonic acid (H2CO3), which then converts to CO2 and water.
8. Which type of mutation results in a premature stop codon?
A. Silent mutation
B. Missense mutation
C. Frameshift mutation
D. Nonsense mutation
Answer: D
Rationale: A nonsense mutation is a point mutation that changes a codon for an amino acid
into a stop codon.
