C785 Biochemistry Final Exam Version 1 2026 |WGU
1. Which level of protein structure is characterized by the specific sequence of
amino acids joined by peptide bonds?
A. Secondary structure
B. Tertiary structure
C. Primary structure
D. Quaternary structure
Answer: C
Rationale: The primary structure is the linear sequence of amino acids held together by
covalent peptide bonds.
2. How does a competitive inhibitor affect enzyme kinetics?
A. It increases Km and leaves Vmax unchanged
B. It increases Vmax and decreases Km
C. It decreases Vmax and increases Km
D. It decreases both Km and Vmax
Answer: A
Rationale: Competitive inhibitors compete for the active site, which increases the amount
of substrate needed to reach half-maximal velocity (Km), but the maximum velocity (Vmax)
can still be reached with enough substrate.
,3. Which of the following describes the Bohr effect on hemoglobin?
A. Low pH and high CO2 increase oxygen affinity
B. Low pH and high CO2 decrease oxygen affinity
C. High pH and low CO2 decrease oxygen affinity
D. Increased 2,3-BPG increases oxygen affinity
Answer: B
Rationale: The Bohr effect states that hemoglobin’s oxygen binding affinity is inversely
related to acidity and to the concentration of carbon dioxide.
4. In DNA replication, which enzyme is responsible for unwinding the double
helix?
A. DNA Polymerase
B. Helicase
C. Ligase
D. Primase
Answer: B
Rationale: Helicase breaks the hydrogen bonds between bases to unwind the DNA double
helix for replication.
5. Which molecule acts as the primary signal for the ‘fed state’ and promotes
glucose uptake in muscles?
A. Glucagon
B. Epinephrine
C. Cortisol
D. Insulin
Answer: D
Rationale: Insulin is released by the pancreas in response to high blood glucose, signaling
cells to take up glucose and store it as glycogen.
, 6. What is the rate-limiting enzyme of glycolysis?
A. Hexokinase
B. Pyruvate Kinase
C. Phosphofructokinase-1 (PFK-1)
D. Aldolase
Answer: C
Rationale: PFK-1 is the primary regulatory and rate-limiting enzyme of the glycolytic
pathway.
7. Which amino acid is involved in forming disulfide bridges that stabilize
tertiary structure?
A. Methionine
B. Cysteine
C. Serine
D. Alanine
Answer: B
Rationale: Cysteine contains a thiol (-SH) group that can oxidize to form a covalent
disulfide bond with another cysteine.
8. During DNA replication, the lagging strand is synthesized in short segments
called:
A. Replication forks
B. Okazaki fragments
C. Introns
D. Promoters
Answer: B
Rationale: Because DNA polymerase only works 5’ to 3’, the lagging strand must be
synthesized discontinuously in Okazaki fragments.
1. Which level of protein structure is characterized by the specific sequence of
amino acids joined by peptide bonds?
A. Secondary structure
B. Tertiary structure
C. Primary structure
D. Quaternary structure
Answer: C
Rationale: The primary structure is the linear sequence of amino acids held together by
covalent peptide bonds.
2. How does a competitive inhibitor affect enzyme kinetics?
A. It increases Km and leaves Vmax unchanged
B. It increases Vmax and decreases Km
C. It decreases Vmax and increases Km
D. It decreases both Km and Vmax
Answer: A
Rationale: Competitive inhibitors compete for the active site, which increases the amount
of substrate needed to reach half-maximal velocity (Km), but the maximum velocity (Vmax)
can still be reached with enough substrate.
,3. Which of the following describes the Bohr effect on hemoglobin?
A. Low pH and high CO2 increase oxygen affinity
B. Low pH and high CO2 decrease oxygen affinity
C. High pH and low CO2 decrease oxygen affinity
D. Increased 2,3-BPG increases oxygen affinity
Answer: B
Rationale: The Bohr effect states that hemoglobin’s oxygen binding affinity is inversely
related to acidity and to the concentration of carbon dioxide.
4. In DNA replication, which enzyme is responsible for unwinding the double
helix?
A. DNA Polymerase
B. Helicase
C. Ligase
D. Primase
Answer: B
Rationale: Helicase breaks the hydrogen bonds between bases to unwind the DNA double
helix for replication.
5. Which molecule acts as the primary signal for the ‘fed state’ and promotes
glucose uptake in muscles?
A. Glucagon
B. Epinephrine
C. Cortisol
D. Insulin
Answer: D
Rationale: Insulin is released by the pancreas in response to high blood glucose, signaling
cells to take up glucose and store it as glycogen.
, 6. What is the rate-limiting enzyme of glycolysis?
A. Hexokinase
B. Pyruvate Kinase
C. Phosphofructokinase-1 (PFK-1)
D. Aldolase
Answer: C
Rationale: PFK-1 is the primary regulatory and rate-limiting enzyme of the glycolytic
pathway.
7. Which amino acid is involved in forming disulfide bridges that stabilize
tertiary structure?
A. Methionine
B. Cysteine
C. Serine
D. Alanine
Answer: B
Rationale: Cysteine contains a thiol (-SH) group that can oxidize to form a covalent
disulfide bond with another cysteine.
8. During DNA replication, the lagging strand is synthesized in short segments
called:
A. Replication forks
B. Okazaki fragments
C. Introns
D. Promoters
Answer: B
Rationale: Because DNA polymerase only works 5’ to 3’, the lagging strand must be
synthesized discontinuously in Okazaki fragments.
