C785 Biochemistry: Acid-Base Balance & Metabolic Integration
Practice Pack 2026/2027 WGU
1. Which of the following equations is primarily used to determine the pH of a
buffer solution based on the pKa and the ratio of conjugate base to weak acid?
A. Henderson-Hasselbalch Equation
B. Michaelis-Menten Equation
C. Nernst Equation
D. Lineweaver-Burk Plot
Answer: A
Rationale: The Henderson-Hasselbalch equation (pH = pKa + log([A-]/[HA])) is used to
calculate the pH of a buffer system.
2. What is the normal physiological range for arterial blood pH?
A. 7.00 - 7.15
B. 6.85 - 6.95
C. 7.55 - 7.65
D. 7.35 - 7.45
Answer: D
Rationale: Normal arterial blood pH is tightly regulated between 7.35 and 7.45.
,3. In the bicarbonate buffer system, which enzyme catalyzes the conversion of
CO2 and H2O into carbonic acid?
A. Lactate Dehydrogenase
B. Pyruvate Carboxylase
C. Bicarbonate Synthetase
D. Carbonic Anhydrase
Answer: D
Rationale: Carbonic anhydrase facilitates the rapid interconversion of carbon dioxide and
water to bicarbonate and hydrogen ions.
4. Which condition is characterized by a decrease in blood pH and an increase in
pCO2?
A. Metabolic Alkalosis
B. Respiratory Alkalosis
C. Metabolic Acidosis
D. Respiratory Acidosis
Answer: D
Rationale: Respiratory acidosis occurs when hypoventilation leads to an accumulation of
CO2, lowering the pH.
5. A patient presents with a pH of 7.25, low HCO3-, and a normal pCO2. What is
the most likely diagnosis?
A. Metabolic Acidosis
B. Respiratory Acidosis
C. Metabolic Alkalosis
D. Respiratory Alkalosis
Answer: A
Rationale: Metabolic acidosis is indicated by a low pH and a primary decrease in
bicarbonate (HCO3-).
, 6. How do the lungs compensate for metabolic acidosis?
A. By decreasing the respiratory rate to retain CO2
B. By decreasing the tidal volume
C. By secreting more bicarbonate into the bloodstream
D. By increasing the respiratory rate to exhale more CO2
Answer: D
Rationale: The lungs compensate for metabolic acidosis via hyperventilation to reduce
pCO2 levels, which helps raise the pH.
7. Which organ is responsible for the long-term regulation of acid-base balance
by excreting hydrogen ions and reabsorbing bicarbonate?
A. Lungs
B. Liver
C. Pancreas
D. Kidneys
Answer: D
Rationale: The kidneys manage long-term acid-base balance through the secretion of H+
and the reabsorption/generation of HCO3-.
8. Which of the following serves as the major intracellular buffer?
A. Bicarbonate
B. Phosphate and Proteins
C. Chloride
D. Sodium
Answer: B
Rationale: Phosphate and various proteins (including hemoglobin in RBCs) serve as the
primary intracellular buffers.
Practice Pack 2026/2027 WGU
1. Which of the following equations is primarily used to determine the pH of a
buffer solution based on the pKa and the ratio of conjugate base to weak acid?
A. Henderson-Hasselbalch Equation
B. Michaelis-Menten Equation
C. Nernst Equation
D. Lineweaver-Burk Plot
Answer: A
Rationale: The Henderson-Hasselbalch equation (pH = pKa + log([A-]/[HA])) is used to
calculate the pH of a buffer system.
2. What is the normal physiological range for arterial blood pH?
A. 7.00 - 7.15
B. 6.85 - 6.95
C. 7.55 - 7.65
D. 7.35 - 7.45
Answer: D
Rationale: Normal arterial blood pH is tightly regulated between 7.35 and 7.45.
,3. In the bicarbonate buffer system, which enzyme catalyzes the conversion of
CO2 and H2O into carbonic acid?
A. Lactate Dehydrogenase
B. Pyruvate Carboxylase
C. Bicarbonate Synthetase
D. Carbonic Anhydrase
Answer: D
Rationale: Carbonic anhydrase facilitates the rapid interconversion of carbon dioxide and
water to bicarbonate and hydrogen ions.
4. Which condition is characterized by a decrease in blood pH and an increase in
pCO2?
A. Metabolic Alkalosis
B. Respiratory Alkalosis
C. Metabolic Acidosis
D. Respiratory Acidosis
Answer: D
Rationale: Respiratory acidosis occurs when hypoventilation leads to an accumulation of
CO2, lowering the pH.
5. A patient presents with a pH of 7.25, low HCO3-, and a normal pCO2. What is
the most likely diagnosis?
A. Metabolic Acidosis
B. Respiratory Acidosis
C. Metabolic Alkalosis
D. Respiratory Alkalosis
Answer: A
Rationale: Metabolic acidosis is indicated by a low pH and a primary decrease in
bicarbonate (HCO3-).
, 6. How do the lungs compensate for metabolic acidosis?
A. By decreasing the respiratory rate to retain CO2
B. By decreasing the tidal volume
C. By secreting more bicarbonate into the bloodstream
D. By increasing the respiratory rate to exhale more CO2
Answer: D
Rationale: The lungs compensate for metabolic acidosis via hyperventilation to reduce
pCO2 levels, which helps raise the pH.
7. Which organ is responsible for the long-term regulation of acid-base balance
by excreting hydrogen ions and reabsorbing bicarbonate?
A. Lungs
B. Liver
C. Pancreas
D. Kidneys
Answer: D
Rationale: The kidneys manage long-term acid-base balance through the secretion of H+
and the reabsorption/generation of HCO3-.
8. Which of the following serves as the major intracellular buffer?
A. Bicarbonate
B. Phosphate and Proteins
C. Chloride
D. Sodium
Answer: B
Rationale: Phosphate and various proteins (including hemoglobin in RBCs) serve as the
primary intracellular buffers.
