Biochemistry Final Exam Preparation 2026 |WGU
1. Which of the following describes the secondary structure of a protein?
A. The local folding patterns such as alpha-helices and beta-sheets
B. The sequence of amino acids in a polypeptide chain
C. The overall three-dimensional shape of a single polypeptide
D. The arrangement of multiple polypeptide subunits
Answer: A
Rationale: Secondary structure refers to the local spatial arrangement of the polypeptide
backbone, stabilized by hydrogen bonds between atoms of the peptide backbone, resulting
in alpha-helices and beta-pleated sheets.
2. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. DNA Ligase
C. Primase
D. Helicase
Answer: D
Rationale: Helicase is the enzyme that breaks the hydrogen bonds between the
nitrogenous bases to separate the two strands of DNA, creating a replication fork.
,3. In the Michaelis-Menten model, what does the Km value represent?
A. The substrate concentration at which the reaction velocity is half of Vmax
B. The maximum velocity of the reaction
C. The total enzyme concentration
D. The rate constant for the formation of the product
Answer: A
Rationale: Km, the Michaelis constant, is the substrate concentration at which the reaction
rate is 50% of the maximum velocity (Vmax), indicating the affinity of the enzyme for its
substrate.
4. Which molecule acts as the final electron acceptor in the electron transport
chain under aerobic conditions?
A. NAD+
B. FAD
C. Oxygen
D. Water
Answer: C
Rationale: In aerobic respiration, molecular oxygen (O2) is the final electron acceptor,
which then combines with protons to form water.
5. What is the primary effect of 2,3-bisphosphoglycerate (2,3-BPG) on
hemoglobin?
A. It increases hemoglobin’s affinity for oxygen
B. It prevents hemoglobin from binding to carbon dioxide
C. It stabilizes the R-state of hemoglobin
D. It decreases hemoglobin’s affinity for oxygen, promoting oxygen release
Answer: D
, Rationale: 2,3-BPG binds to the center of the hemoglobin tetramer in the T-state (tense
state), stabilizing it and reducing oxygen affinity, which facilitates the unloading of oxygen
to tissues.
6. How does a competitive inhibitor affect the kinetic parameters of an enzyme?
A. Vmax remains the same, Km increases
B. Vmax decreases, Km remains the same
C. Vmax decreases, Km decreases
D. Vmax remains the same, Km decreases
Answer: A
Rationale: A competitive inhibitor competes with the substrate for the active site.
Increasing the substrate concentration can overcome the inhibitor, so Vmax is unchanged,
but more substrate is needed to reach half-maximal velocity, thus Km increases.
7. Which process occurs in the mitochondrial matrix?
A. Glycolysis
B. Oxidative Phosphorylation
C. Citric Acid Cycle
D. Transcription
Answer: C
Rationale: The Citric Acid Cycle (Krebs cycle) takes place in the mitochondrial matrix,
whereas glycolysis occurs in the cytoplasm and oxidative phosphorylation occurs on the
inner mitochondrial membrane.
8. Which base is found in RNA but not in DNA?
A. Adenine
B. Uracil
C. Guanine
D. Thymine
Answer: B
1. Which of the following describes the secondary structure of a protein?
A. The local folding patterns such as alpha-helices and beta-sheets
B. The sequence of amino acids in a polypeptide chain
C. The overall three-dimensional shape of a single polypeptide
D. The arrangement of multiple polypeptide subunits
Answer: A
Rationale: Secondary structure refers to the local spatial arrangement of the polypeptide
backbone, stabilized by hydrogen bonds between atoms of the peptide backbone, resulting
in alpha-helices and beta-pleated sheets.
2. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. DNA Ligase
C. Primase
D. Helicase
Answer: D
Rationale: Helicase is the enzyme that breaks the hydrogen bonds between the
nitrogenous bases to separate the two strands of DNA, creating a replication fork.
,3. In the Michaelis-Menten model, what does the Km value represent?
A. The substrate concentration at which the reaction velocity is half of Vmax
B. The maximum velocity of the reaction
C. The total enzyme concentration
D. The rate constant for the formation of the product
Answer: A
Rationale: Km, the Michaelis constant, is the substrate concentration at which the reaction
rate is 50% of the maximum velocity (Vmax), indicating the affinity of the enzyme for its
substrate.
4. Which molecule acts as the final electron acceptor in the electron transport
chain under aerobic conditions?
A. NAD+
B. FAD
C. Oxygen
D. Water
Answer: C
Rationale: In aerobic respiration, molecular oxygen (O2) is the final electron acceptor,
which then combines with protons to form water.
5. What is the primary effect of 2,3-bisphosphoglycerate (2,3-BPG) on
hemoglobin?
A. It increases hemoglobin’s affinity for oxygen
B. It prevents hemoglobin from binding to carbon dioxide
C. It stabilizes the R-state of hemoglobin
D. It decreases hemoglobin’s affinity for oxygen, promoting oxygen release
Answer: D
, Rationale: 2,3-BPG binds to the center of the hemoglobin tetramer in the T-state (tense
state), stabilizing it and reducing oxygen affinity, which facilitates the unloading of oxygen
to tissues.
6. How does a competitive inhibitor affect the kinetic parameters of an enzyme?
A. Vmax remains the same, Km increases
B. Vmax decreases, Km remains the same
C. Vmax decreases, Km decreases
D. Vmax remains the same, Km decreases
Answer: A
Rationale: A competitive inhibitor competes with the substrate for the active site.
Increasing the substrate concentration can overcome the inhibitor, so Vmax is unchanged,
but more substrate is needed to reach half-maximal velocity, thus Km increases.
7. Which process occurs in the mitochondrial matrix?
A. Glycolysis
B. Oxidative Phosphorylation
C. Citric Acid Cycle
D. Transcription
Answer: C
Rationale: The Citric Acid Cycle (Krebs cycle) takes place in the mitochondrial matrix,
whereas glycolysis occurs in the cytoplasm and oxidative phosphorylation occurs on the
inner mitochondrial membrane.
8. Which base is found in RNA but not in DNA?
A. Adenine
B. Uracil
C. Guanine
D. Thymine
Answer: B
