Biochemistry Final Exam Comprehensive Study Set 2026 |WGU
1. How does a competitive inhibitor affect the kinetic parameters of an enzyme?
A. It increases Vmax and decreases Km.
B. It decreases Vmax and has no effect on Km.
C. It increases Km and has no effect on Vmax.
D. It decreases both Vmax and Km.
Answer: C
Rationale: A competitive inhibitor competes with the substrate for the active site.
Increasing substrate concentration can overcome inhibition, so Vmax remains the same,
but more substrate is needed to reach half-maximal velocity, thus increasing the Km.
2. Which level of protein structure is characterized by the sequence of amino
acids linked by peptide bonds?
A. Tertiary structure
B. Secondary structure
C. Primary structure
D. Quaternary structure
Answer: C
Rationale: The primary structure is the linear sequence of amino acids in a polypeptide
chain.
,3. Which of the following conditions will cause a right shift in the hemoglobin-
oxygen dissociation curve?
A. Decreased temperature
B. Decreased PCO2
C. Increased 2,3-BPG
D. Increased pH
Answer: C
Rationale: A right shift indicates a lower affinity for oxygen, facilitating its release to
tissues. This is caused by increased 2,3-BPG, increased CO2, increased H+ (lower pH), and
increased temperature.
4. What is the rate-limiting enzyme of glycolysis?
A. Phosphofructokinase-1 (PFK-1)
B. Hexokinase
C. Pyruvate Kinase
D. Aldolase
Answer: A
Rationale: PFK-1 is the primary rate-limiting and regulated step in glycolysis, converting
Fructose-6-phosphate to Fructose-1,6-bisphosphate.
5. Which nitrogenous base is found in RNA but not in DNA?
A. Adenine
B. Thymine
C. Uracil
D. Cytosine
Answer: C
Rationale: RNA contains Uracil (U) instead of Thymine (T), which is found in DNA.
, 6. Gluconeogenesis primarily occurs in which organ?
A. Liver
B. Skeletal muscle
C. Brain
D. Pancreas
Answer: A
Rationale: The liver is the primary site of gluconeogenesis, ensuring blood glucose levels
are maintained during fasting.
7. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Ligase
C. Primase
D. Helicase
Answer: D
Rationale: Helicase breaks the hydrogen bonds between the two strands of DNA to unwind
the helix.
8. In the Electron Transport Chain, which complex does NOT pump protons into
the mitochondrial intermembrane space?
A. Complex II
B. Complex I
C. Complex III
D. Complex IV
Answer: A
Rationale: Complex II (succinate dehydrogenase) transfers electrons but does not have the
energy to pump protons across the membrane.
1. How does a competitive inhibitor affect the kinetic parameters of an enzyme?
A. It increases Vmax and decreases Km.
B. It decreases Vmax and has no effect on Km.
C. It increases Km and has no effect on Vmax.
D. It decreases both Vmax and Km.
Answer: C
Rationale: A competitive inhibitor competes with the substrate for the active site.
Increasing substrate concentration can overcome inhibition, so Vmax remains the same,
but more substrate is needed to reach half-maximal velocity, thus increasing the Km.
2. Which level of protein structure is characterized by the sequence of amino
acids linked by peptide bonds?
A. Tertiary structure
B. Secondary structure
C. Primary structure
D. Quaternary structure
Answer: C
Rationale: The primary structure is the linear sequence of amino acids in a polypeptide
chain.
,3. Which of the following conditions will cause a right shift in the hemoglobin-
oxygen dissociation curve?
A. Decreased temperature
B. Decreased PCO2
C. Increased 2,3-BPG
D. Increased pH
Answer: C
Rationale: A right shift indicates a lower affinity for oxygen, facilitating its release to
tissues. This is caused by increased 2,3-BPG, increased CO2, increased H+ (lower pH), and
increased temperature.
4. What is the rate-limiting enzyme of glycolysis?
A. Phosphofructokinase-1 (PFK-1)
B. Hexokinase
C. Pyruvate Kinase
D. Aldolase
Answer: A
Rationale: PFK-1 is the primary rate-limiting and regulated step in glycolysis, converting
Fructose-6-phosphate to Fructose-1,6-bisphosphate.
5. Which nitrogenous base is found in RNA but not in DNA?
A. Adenine
B. Thymine
C. Uracil
D. Cytosine
Answer: C
Rationale: RNA contains Uracil (U) instead of Thymine (T), which is found in DNA.
, 6. Gluconeogenesis primarily occurs in which organ?
A. Liver
B. Skeletal muscle
C. Brain
D. Pancreas
Answer: A
Rationale: The liver is the primary site of gluconeogenesis, ensuring blood glucose levels
are maintained during fasting.
7. Which enzyme is responsible for unwinding the DNA double helix during
replication?
A. DNA Polymerase
B. Ligase
C. Primase
D. Helicase
Answer: D
Rationale: Helicase breaks the hydrogen bonds between the two strands of DNA to unwind
the helix.
8. In the Electron Transport Chain, which complex does NOT pump protons into
the mitochondrial intermembrane space?
A. Complex II
B. Complex I
C. Complex III
D. Complex IV
Answer: A
Rationale: Complex II (succinate dehydrogenase) transfers electrons but does not have the
energy to pump protons across the membrane.
