Answer: Volume of air inhaled/exhaled in a normal breath (~500 mL).
- A The maximum air volume the lungs can hold after forced inhalation
- B Volume of air inhaled/exhaled in a normal breath (~500 mL)
- C The air remaining in lungs after the most forceful possible exhalation
- D The maximum air that can be exhaled after the deepest possible inhalation
Correct answer: B. Volume of air inhaled/exhaled in a normal breath (~500 mL)
Explanation: Tidal volume: volume of air moved in or out per normal breath, about 500 mL at rest.
The S-shaped (sigmoid) curve reflects cooperative binding between Hb's four O₂ sites; the Bohr effect shifts the whole curve to the right under conditions found in actively respiring tissue (more CO₂, more acid, more heat), making haemoglobin release oxygen more readily exactly where it's needed.
Concept context
The mechanics of breathing, lung volumes, gas transport in blood, the Bohr effect, and respiratory regulation.