IB Biology SL 3.1.15 Ventilation and gas exchange Question Bank
Practise IB Biology SL 3.1.15 by explaining how pH and exercise change ventilation rate.
- Syllabus
- First assessment 2025
- Course
- Biology SL
- Level
- SL
Practise IB Biology SL 3.1.15 by explaining how pH and exercise change ventilation rate.
The fMRI scan shows a human brain.

Explain control of breathing rate by the structure labelled X .
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;
Marking guidance:
Accept inverse responses for decreased carbon dioxide (for mp c to f)
For mp d accept a valid mechanism
3 max