C785 Biochemistry Final Exam Practice 2026 |WGU
1. Which type of bond stabilizes the primary structure of a protein?
A. Hydrogen bonds
B. Disulfide bridges
C. Ionic bonds
D. Peptide bonds
Answer: D
Rationale: The primary structure of a protein is the linear sequence of amino acids, which
are held together by covalent peptide bonds.
2. In enzyme kinetics, what does the Michaelis constant (Km) represent?
A. The maximum velocity of the reaction
B. The substrate concentration at which the reaction velocity is half of Vmax
C. The total concentration of enzyme available
D. The energy required to reach the transition state
Answer: B
Rationale: Km is defined as the substrate concentration at which the reaction rate is
exactly half of the maximum velocity (Vmax).
3. Which of the following describes the Bohr effect on hemoglobin?
A. High pH decreases hemoglobin’s affinity for oxygen
B. Low pH decreases hemoglobin’s affinity for oxygen
C. Low CO2 levels promote oxygen unloading
D. High oxygen levels cause hemoglobin to release CO2
Answer: B
,Rationale: The Bohr effect states that lower pH (more acidic) and higher CO2 levels shift
the oxygen dissociation curve to the right, decreasing hemoglobin’s affinity for oxygen to
facilitate unloading in tissues.
4. What is the effect of a competitive inhibitor on an enzyme’s Vmax and Km?
A. Vmax decreases, Km stays the same
B. Vmax stays the same, Km increases
C. Vmax increases, Km decreases
D. Both Vmax and Km stay the same
Answer: B
Rationale: Competitive inhibitors compete for the active site, increasing the apparent Km
(more substrate is needed to reach half Vmax), but the Vmax remains unchanged because
high substrate concentrations can outcompete the inhibitor.
5. Which molecule serves as the final electron acceptor in the electron transport
chain during aerobic respiration?
A. Oxygen
B. FAD
C. NAD+
D. Water
Answer: A
Rationale: Oxygen acts as the terminal electron acceptor in the electron transport chain,
where it is reduced to form water.
, 6. In DNA replication, which enzyme is responsible for unwinding the double
helix?
A. DNA Polymerase
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between the two strands of the DNA
double helix to unwind it for replication.
7. What is the primary site of gluconeogenesis in the human body?
A. Skeletal muscle
B. Adipose tissue
C. Pancreas
D. Liver
Answer: D
Rationale: Gluconeogenesis, the synthesis of glucose from non-carbohydrate precursors,
occurs primarily in the liver (and to a lesser extent in the kidneys).
8. Which hormone is released by the pancreas in response to high blood glucose
levels?
A. Glucagon
B. Epinephrine
C. Insulin
D. Cortisol
Answer: C
Rationale: Insulin is secreted by the beta cells of the pancreas to promote glucose uptake
by cells and lower blood sugar levels.
1. Which type of bond stabilizes the primary structure of a protein?
A. Hydrogen bonds
B. Disulfide bridges
C. Ionic bonds
D. Peptide bonds
Answer: D
Rationale: The primary structure of a protein is the linear sequence of amino acids, which
are held together by covalent peptide bonds.
2. In enzyme kinetics, what does the Michaelis constant (Km) represent?
A. The maximum velocity of the reaction
B. The substrate concentration at which the reaction velocity is half of Vmax
C. The total concentration of enzyme available
D. The energy required to reach the transition state
Answer: B
Rationale: Km is defined as the substrate concentration at which the reaction rate is
exactly half of the maximum velocity (Vmax).
3. Which of the following describes the Bohr effect on hemoglobin?
A. High pH decreases hemoglobin’s affinity for oxygen
B. Low pH decreases hemoglobin’s affinity for oxygen
C. Low CO2 levels promote oxygen unloading
D. High oxygen levels cause hemoglobin to release CO2
Answer: B
,Rationale: The Bohr effect states that lower pH (more acidic) and higher CO2 levels shift
the oxygen dissociation curve to the right, decreasing hemoglobin’s affinity for oxygen to
facilitate unloading in tissues.
4. What is the effect of a competitive inhibitor on an enzyme’s Vmax and Km?
A. Vmax decreases, Km stays the same
B. Vmax stays the same, Km increases
C. Vmax increases, Km decreases
D. Both Vmax and Km stay the same
Answer: B
Rationale: Competitive inhibitors compete for the active site, increasing the apparent Km
(more substrate is needed to reach half Vmax), but the Vmax remains unchanged because
high substrate concentrations can outcompete the inhibitor.
5. Which molecule serves as the final electron acceptor in the electron transport
chain during aerobic respiration?
A. Oxygen
B. FAD
C. NAD+
D. Water
Answer: A
Rationale: Oxygen acts as the terminal electron acceptor in the electron transport chain,
where it is reduced to form water.
, 6. In DNA replication, which enzyme is responsible for unwinding the double
helix?
A. DNA Polymerase
B. Ligase
C. Helicase
D. Primase
Answer: C
Rationale: Helicase breaks the hydrogen bonds between the two strands of the DNA
double helix to unwind it for replication.
7. What is the primary site of gluconeogenesis in the human body?
A. Skeletal muscle
B. Adipose tissue
C. Pancreas
D. Liver
Answer: D
Rationale: Gluconeogenesis, the synthesis of glucose from non-carbohydrate precursors,
occurs primarily in the liver (and to a lesser extent in the kidneys).
8. Which hormone is released by the pancreas in response to high blood glucose
levels?
A. Glucagon
B. Epinephrine
C. Insulin
D. Cortisol
Answer: C
Rationale: Insulin is secreted by the beta cells of the pancreas to promote glucose uptake
by cells and lower blood sugar levels.
