Q5 - CO2, Not O2, Drives Everyday Breathing Rate
John Haldane (1892-1962) discovered many mechanisms which control gas exchange and breathing. The effect of altering the pressure of oxygen or carbon dioxide in air sacs (alveoli) within human lungs on the volume of air breathed every minute was recorded. Alveolar air, at sea level, usually has Po = 100 mmHg, Pco = 40 mmHg. 2 2
Using the information and data, determine which of the statements are true or which are false.
A. Increasing blood acidity (lowering pH) increases breathing rate.
B. Breathing rate is determined by the oxygen content of blood in normal conditions.
C. At high altitude (atmospheric pressure < 50 % of sea level), falling carbon dioxide pressure in the blood has a greater impact on breathing than falling oxygen pressure.
D. Total blood oxygen content changes negligibly when alveolar oxygen pressure is increased from 50 mmHg to 150 mmHg.
Question reproduced from IBO 2017, Theoretical Exam B, licensed under CC BY-NC-SA 4.0 - attributed to the International Biology Olympiad. Open the full exam PDF · Official answer key & worked solutions