IB Biology SL C3.1.15 Ventilation Rate Feedback Control Questions

Explore how CO₂-driven pH changes activate chemoreceptors and the medulla, which adjusts diaphragm and intercostal activity to control ventilation in IB Biology SL C3.1.15.

Exam points

Explain how CO₂-driven blood-pH changes are detected and alter ventilation through the medulla and respiratory muscles.
Interpret arterial-pH or atmospheric-CO₂ data to relate chemoreceptor feedback to ventilation rate and air volume.

[Maximum number: 3]

The fMRI scan shows a human brain.

Figure for Question IB Biology SL C3.1.15 Ventilation Rate Feedback Control Questions question 1 — IB Biology SL

Explain control of breathing rate by the structure labelled X.

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a	breathing centre in medulla (oblongata)/brain stem;
b	operates via autonomic nervous system;
c	blood pH reduced/more acidic (with increased carbon dioxide);
d	(Medulla) causes deeper/faster breathing;
e	expels more carbon dioxide from lungs/blood;
f	raises pH of blood;

IB Biology SL C3.1.15 Ventilation Rate Feedback Control Questions question 1