,BIOL252/BIOL 252 Module 8 Exam | Human Anatomy &
Physiology II w/ Lab | Portage Learning | Q & A | 2026/2027
Edition (PDF)
**1. Approximately what percentage of the human body weight is made up of water?**
A) 20-30%
B) 40-50%
C) 50-60%
D) 70-80%
Correct Answer: 50-60%
Rationale: Water constitutes about 50-60% of the total body weight in adults, varying based on age, sex,
and body composition. Lean individuals have a higher percentage of body water (up to 60-70%)
compared to those with more adipose tissue, which has lower water content.
**2. Which fluid compartment contains approximately two-thirds of the body's total water?**
A) Intracellular fluid (ICF)
B) Extracellular fluid (ECF)
C) Interstitial fluid
D) Plasma
Correct Answer: Intracellular fluid (ICF)
Rationale: The intracellular fluid (ICF) compartment contains about two-thirds (approximately 40% of
body weight) of the body's total water. The extracellular fluid (ECF) compartment contains the
remaining one-third (about 20% of body weight), which includes interstitial fluid, plasma, and other
minor fluid compartments.
**3. The extracellular fluid (ECF) compartment is composed of which of the following?**
A) Intracellular fluid and interstitial fluid
,B) Plasma and interstitial fluid
C) Plasma and intracellular fluid
D) Interstitial fluid and transcellular fluid
Correct Answer: Plasma and interstitial fluid
Rationale: The extracellular fluid (ECF) compartment includes plasma (the fluid portion of blood) and
interstitial fluid (the fluid that bathes the cells). Other minor ECF components include lymph,
cerebrospinal fluid, and other transcellular fluids.
**4. Which of the following is the major cation in the intracellular fluid (ICF)?**
A) Sodium (Na⁺)
B) Potassium (K⁺)
C) Calcium (Ca²⁺)
D) Magnesium (Mg²⁺)
Correct Answer: Potassium (K⁺)
Rationale: Potassium (K⁺) is the predominant cation in the intracellular fluid, playing a crucial role in
maintaining membrane potential and cellular function. Sodium (Na⁺) is the major cation in the
extracellular fluid, while calcium and magnesium are present in smaller concentrations.
**5. The primary cation in the extracellular fluid (ECF) is:**
A) Potassium (K⁺)
B) Calcium (Ca²⁺)
C) Sodium (Na⁺)
D) Magnesium (Mg²⁺)
Correct Answer: Sodium (Na⁺)
, Rationale: Sodium (Na⁺) is the most abundant cation in the extracellular fluid, contributing to osmotic
pressure, fluid balance, and nerve impulse transmission. Its concentration is tightly regulated by
hormones like aldosterone and atrial natriuretic peptide.
**6. The primary anion in the extracellular fluid is:**
A) Phosphate (PO₄³⁻)
B) Bicarbonate (HCO₃⁻)
C) Chloride (Cl⁻)
D) Sulfate (SO₄²⁻)
Correct Answer: Chloride (Cl⁻)
Rationale: Chloride (Cl⁻) is the major anion in the extracellular fluid, playing a key role in maintaining
electrical neutrality and fluid balance. It often follows sodium to maintain osmotic balance, and it is
involved in the chloride shift during CO₂ transport.
**7. Osmosis is the movement of water across a semipermeable membrane from an area of:**
A) Low solute concentration to high solute concentration
B) High solute concentration to low solute concentration
C) Equal solute concentration
D) High pressure to low pressure
Correct Answer: Low solute concentration to high solute concentration
Rationale: Osmosis is the passive movement of water across a semipermeable membrane from an area
of lower solute concentration (higher water concentration) to an area of higher solute concentration
(lower water concentration). This movement continues until osmotic equilibrium is reached.
**8. Osmolarity is a measure of the total concentration of solute particles in a solution. The normal
osmolarity of plasma is approximately:**
A) 200-250 mOsm/L
Physiology II w/ Lab | Portage Learning | Q & A | 2026/2027
Edition (PDF)
**1. Approximately what percentage of the human body weight is made up of water?**
A) 20-30%
B) 40-50%
C) 50-60%
D) 70-80%
Correct Answer: 50-60%
Rationale: Water constitutes about 50-60% of the total body weight in adults, varying based on age, sex,
and body composition. Lean individuals have a higher percentage of body water (up to 60-70%)
compared to those with more adipose tissue, which has lower water content.
**2. Which fluid compartment contains approximately two-thirds of the body's total water?**
A) Intracellular fluid (ICF)
B) Extracellular fluid (ECF)
C) Interstitial fluid
D) Plasma
Correct Answer: Intracellular fluid (ICF)
Rationale: The intracellular fluid (ICF) compartment contains about two-thirds (approximately 40% of
body weight) of the body's total water. The extracellular fluid (ECF) compartment contains the
remaining one-third (about 20% of body weight), which includes interstitial fluid, plasma, and other
minor fluid compartments.
**3. The extracellular fluid (ECF) compartment is composed of which of the following?**
A) Intracellular fluid and interstitial fluid
,B) Plasma and interstitial fluid
C) Plasma and intracellular fluid
D) Interstitial fluid and transcellular fluid
Correct Answer: Plasma and interstitial fluid
Rationale: The extracellular fluid (ECF) compartment includes plasma (the fluid portion of blood) and
interstitial fluid (the fluid that bathes the cells). Other minor ECF components include lymph,
cerebrospinal fluid, and other transcellular fluids.
**4. Which of the following is the major cation in the intracellular fluid (ICF)?**
A) Sodium (Na⁺)
B) Potassium (K⁺)
C) Calcium (Ca²⁺)
D) Magnesium (Mg²⁺)
Correct Answer: Potassium (K⁺)
Rationale: Potassium (K⁺) is the predominant cation in the intracellular fluid, playing a crucial role in
maintaining membrane potential and cellular function. Sodium (Na⁺) is the major cation in the
extracellular fluid, while calcium and magnesium are present in smaller concentrations.
**5. The primary cation in the extracellular fluid (ECF) is:**
A) Potassium (K⁺)
B) Calcium (Ca²⁺)
C) Sodium (Na⁺)
D) Magnesium (Mg²⁺)
Correct Answer: Sodium (Na⁺)
, Rationale: Sodium (Na⁺) is the most abundant cation in the extracellular fluid, contributing to osmotic
pressure, fluid balance, and nerve impulse transmission. Its concentration is tightly regulated by
hormones like aldosterone and atrial natriuretic peptide.
**6. The primary anion in the extracellular fluid is:**
A) Phosphate (PO₄³⁻)
B) Bicarbonate (HCO₃⁻)
C) Chloride (Cl⁻)
D) Sulfate (SO₄²⁻)
Correct Answer: Chloride (Cl⁻)
Rationale: Chloride (Cl⁻) is the major anion in the extracellular fluid, playing a key role in maintaining
electrical neutrality and fluid balance. It often follows sodium to maintain osmotic balance, and it is
involved in the chloride shift during CO₂ transport.
**7. Osmosis is the movement of water across a semipermeable membrane from an area of:**
A) Low solute concentration to high solute concentration
B) High solute concentration to low solute concentration
C) Equal solute concentration
D) High pressure to low pressure
Correct Answer: Low solute concentration to high solute concentration
Rationale: Osmosis is the passive movement of water across a semipermeable membrane from an area
of lower solute concentration (higher water concentration) to an area of higher solute concentration
(lower water concentration). This movement continues until osmotic equilibrium is reached.
**8. Osmolarity is a measure of the total concentration of solute particles in a solution. The normal
osmolarity of plasma is approximately:**
A) 200-250 mOsm/L
