WGU C785 BIOCHEMISTRY
COMPREHENSIVE FINAL EXAM 2026
QUESTIONS AND ANSWERS
1. Which enzyme is responsible for relieving the torsional strain caused by DNA unwinding
during replication?
A. DNA Helicase
B. Primase
C. DNA Polymerase III
D. DNA Topoisomerase (Gyrase)
Answer: D
Conceptual Explanation: DNA Topoisomerase prevents supercoiling and relieves
torsional strain ahead of the replication fork by cutting and rejoining DNA strands.
2. In the Michaelis-Menten model, what does the Km value represent?
A. The maximum velocity of the reaction
B. The substrate concentration at which the reaction rate is half of Vmax
C. The total concentration of the enzyme
D. The equilibrium constant of the chemical reaction
Answer: B
,Conceptual Explanation: Km is the substrate concentration at which the reaction velocity
is 50% of the maximum velocity (Vmax). It reflects the affinity of the enzyme for its
substrate.
3. Which of the following describes the secondary structure of a protein?
A. The sequence of amino acids in a polypeptide chain
B. The 3D folding of a single polypeptide chain
C. Local folding patterns like alpha-helices and beta-pleated sheets
D. The interaction between multiple polypeptide subunits
Answer: C
Conceptual Explanation: Secondary structure refers to localized repeating patterns
stabilized by hydrogen bonds between the backbone carbonyl and amide groups.
4. How does 2,3-Bisphosphoglycerate (2,3-BPG) affect hemoglobin’s affinity for oxygen?
A. It decreases oxygen affinity by stabilizing the T-state
B. It increases oxygen affinity by stabilizing the R-state
C. It binds to the heme group, blocking oxygen binding
D. It converts hemoglobin into myoglobin
Answer: A
Conceptual Explanation: 2,3-BPG binds to the central cavity of the hemoglobin tetramer,
stabilizing the T-state (Tense) and promoting the release of oxygen into tissues.
, 5. Which metabolic pathway is upregulated by glucagon in the liver?
A. Glycolysis
B. Fatty acid synthesis
C. Glycogen synthesis
D. Gluconeogenesis
Answer: D
Conceptual Explanation: Glucagon signals low blood glucose levels, prompting the liver to
perform gluconeogenesis and glycogenolysis to increase blood sugar.
6. What type of inhibition occurs when the inhibitor binds only to the enzyme-substrate (ES)
complex?
A. Competitive inhibition
B. Uncompetitive inhibition
C. Non-competitive inhibition
D. Irreversible inhibition
Answer: B
Conceptual Explanation: Uncompetitive inhibitors bind to the ES complex, effectively
lowering both Vmax and Km.
COMPREHENSIVE FINAL EXAM 2026
QUESTIONS AND ANSWERS
1. Which enzyme is responsible for relieving the torsional strain caused by DNA unwinding
during replication?
A. DNA Helicase
B. Primase
C. DNA Polymerase III
D. DNA Topoisomerase (Gyrase)
Answer: D
Conceptual Explanation: DNA Topoisomerase prevents supercoiling and relieves
torsional strain ahead of the replication fork by cutting and rejoining DNA strands.
2. In the Michaelis-Menten model, what does the Km value represent?
A. The maximum velocity of the reaction
B. The substrate concentration at which the reaction rate is half of Vmax
C. The total concentration of the enzyme
D. The equilibrium constant of the chemical reaction
Answer: B
,Conceptual Explanation: Km is the substrate concentration at which the reaction velocity
is 50% of the maximum velocity (Vmax). It reflects the affinity of the enzyme for its
substrate.
3. Which of the following describes the secondary structure of a protein?
A. The sequence of amino acids in a polypeptide chain
B. The 3D folding of a single polypeptide chain
C. Local folding patterns like alpha-helices and beta-pleated sheets
D. The interaction between multiple polypeptide subunits
Answer: C
Conceptual Explanation: Secondary structure refers to localized repeating patterns
stabilized by hydrogen bonds between the backbone carbonyl and amide groups.
4. How does 2,3-Bisphosphoglycerate (2,3-BPG) affect hemoglobin’s affinity for oxygen?
A. It decreases oxygen affinity by stabilizing the T-state
B. It increases oxygen affinity by stabilizing the R-state
C. It binds to the heme group, blocking oxygen binding
D. It converts hemoglobin into myoglobin
Answer: A
Conceptual Explanation: 2,3-BPG binds to the central cavity of the hemoglobin tetramer,
stabilizing the T-state (Tense) and promoting the release of oxygen into tissues.
, 5. Which metabolic pathway is upregulated by glucagon in the liver?
A. Glycolysis
B. Fatty acid synthesis
C. Glycogen synthesis
D. Gluconeogenesis
Answer: D
Conceptual Explanation: Glucagon signals low blood glucose levels, prompting the liver to
perform gluconeogenesis and glycogenolysis to increase blood sugar.
6. What type of inhibition occurs when the inhibitor binds only to the enzyme-substrate (ES)
complex?
A. Competitive inhibition
B. Uncompetitive inhibition
C. Non-competitive inhibition
D. Irreversible inhibition
Answer: B
Conceptual Explanation: Uncompetitive inhibitors bind to the ES complex, effectively
lowering both Vmax and Km.
