The diagram shows the major parts of the human respiratory system. The tidal volume of air inhaled per breath is 500 mL and the anatomical dead‑space volume is 150 mL per breath. A person breathes 12 times per minute at rest.

a) Calculate the alveolar ventilation (in litres per minute) at rest.

b) If the breathing rate increases to 20 breaths per minute while the tidal volume remains the same, calculate the new alveolar ventilation and the percentage increase relative to the resting value.

Question

The diagram shows the major parts of the human respiratory system. The tidal volume of air inhaled per breath is 500 mL and the anatomical dead‑space volume is 150 mL per breath. A person breathes 12 times per minute at rest.

a) Calculate the alveolar ventilation (in litres per minute) at rest.

b) If the breathing rate increases to 20 breaths per minute while the tidal volume remains the same, calculate the new alveolar ventilation and the percentage increase relative to the resting value.

Accepted Answer

Resting alveolar ventilation = 4.2 L min⁻¹; at 20 breaths min⁻¹ = 7.0 L min⁻¹; percentage increase ≈ 66.7 %.

Neco Model Questions Vol1 2025 Biology Question 11

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