Ganong’s Review of Medical Physiology
National Board Type Questions With 100%
Correct Answers And Explanation
Volume I – Chapter 1-10.
,CHAPTER 1
General Principles & Energy Production in Medical
Physiology
Q1.
Which compartment contains the largest percentage of total body water in a healthy adult
male?
A. Plasma
B. Interstitial fluid
C. Intracellular fluid
D. Transcellular fluid
✅ Correct answer: C. Intracellular fluid
Explanation:
About 60% of body weight is water. Of this:
• ~40% is intracellular fluid (ICF)
• ~20% is extracellular fluid (ECF)
Thus, ICF is the largest compartment.
Q2.
Which ion contributes the most to plasma osmolality under normal conditions?
A. Potassium
B. Calcium
C. Sodium
D. Glucose
✅ Correct answer: C. Sodium
Explanation:
Plasma osmolality (~290 mOsm/kg) is mainly determined by Na⁺ and its accompanying anions
(Cl⁻, HCO₃⁻). Glucose and urea contribute much less under normal conditions.
Q3.
,A buffer works best when:
A. pH > pKa
B. pH < pKa
C. pH = pKa
D. Acid concentration is zero
✅ Correct answer: C. pH = pKa
Explanation:
Buffering capacity is maximal when [A⁻] = [HA], which occurs when pH = pKa (Henderson–
Hasselbalch equation).
Q4.
Which of the following best describes osmosis?
A. Diffusion of solute down its gradient
B. Movement of water across a semipermeable membrane
C. Active transport of ions
D. Filtration due to hydrostatic pressure
✅ Correct answer: B
Explanation:
Osmosis is the movement of water across a membrane permeable to water but not solute,
driven by differences in solute concentration.
Q5.
Which property of water makes it an excellent biological solvent?
A. Low dielectric constant
B. Nonpolar structure
C. Hydrogen bonding
D. Low heat capacity
✅ Correct answer: C
Explanation:
Water’s polarity and hydrogen bonding allow it to dissolve ions and polar molecules
efficiently.
, Q6.
Which equation is used to calculate equilibrium potential for an ion?
A. Henderson–Hasselbalch
B. Gibbs–Donnan
C. Nernst
D. Fick
✅ Correct answer: C. Nernst
Explanation:
The Nernst equation calculates the membrane potential at which no net ion movement occurs.
Q7.
The resting membrane potential of most neurons is closest to the equilibrium potential of:
A. Sodium
B. Potassium
C. Calcium
D. Chloride
✅ Correct answer: D. Chloride
Explanation:
Resting membrane potential ≈ –70 mV, which closely matches ECl⁻, due to passive distribution
of chloride ions.
Q8.
Which pump is essential to prevent osmotic swelling of cells?
A. Ca²⁺ ATPase
B. H⁺ ATPase
C. Na⁺/K⁺ ATPase
D. Cl⁻ exchanger
✅ Correct answer: C
National Board Type Questions With 100%
Correct Answers And Explanation
Volume I – Chapter 1-10.
,CHAPTER 1
General Principles & Energy Production in Medical
Physiology
Q1.
Which compartment contains the largest percentage of total body water in a healthy adult
male?
A. Plasma
B. Interstitial fluid
C. Intracellular fluid
D. Transcellular fluid
✅ Correct answer: C. Intracellular fluid
Explanation:
About 60% of body weight is water. Of this:
• ~40% is intracellular fluid (ICF)
• ~20% is extracellular fluid (ECF)
Thus, ICF is the largest compartment.
Q2.
Which ion contributes the most to plasma osmolality under normal conditions?
A. Potassium
B. Calcium
C. Sodium
D. Glucose
✅ Correct answer: C. Sodium
Explanation:
Plasma osmolality (~290 mOsm/kg) is mainly determined by Na⁺ and its accompanying anions
(Cl⁻, HCO₃⁻). Glucose and urea contribute much less under normal conditions.
Q3.
,A buffer works best when:
A. pH > pKa
B. pH < pKa
C. pH = pKa
D. Acid concentration is zero
✅ Correct answer: C. pH = pKa
Explanation:
Buffering capacity is maximal when [A⁻] = [HA], which occurs when pH = pKa (Henderson–
Hasselbalch equation).
Q4.
Which of the following best describes osmosis?
A. Diffusion of solute down its gradient
B. Movement of water across a semipermeable membrane
C. Active transport of ions
D. Filtration due to hydrostatic pressure
✅ Correct answer: B
Explanation:
Osmosis is the movement of water across a membrane permeable to water but not solute,
driven by differences in solute concentration.
Q5.
Which property of water makes it an excellent biological solvent?
A. Low dielectric constant
B. Nonpolar structure
C. Hydrogen bonding
D. Low heat capacity
✅ Correct answer: C
Explanation:
Water’s polarity and hydrogen bonding allow it to dissolve ions and polar molecules
efficiently.
, Q6.
Which equation is used to calculate equilibrium potential for an ion?
A. Henderson–Hasselbalch
B. Gibbs–Donnan
C. Nernst
D. Fick
✅ Correct answer: C. Nernst
Explanation:
The Nernst equation calculates the membrane potential at which no net ion movement occurs.
Q7.
The resting membrane potential of most neurons is closest to the equilibrium potential of:
A. Sodium
B. Potassium
C. Calcium
D. Chloride
✅ Correct answer: D. Chloride
Explanation:
Resting membrane potential ≈ –70 mV, which closely matches ECl⁻, due to passive distribution
of chloride ions.
Q8.
Which pump is essential to prevent osmotic swelling of cells?
A. Ca²⁺ ATPase
B. H⁺ ATPase
C. Na⁺/K⁺ ATPase
D. Cl⁻ exchanger
✅ Correct answer: C
