Biology - Breathing and Exchange of Gases Question with Solution | TestHub

The oxyhaemoglobin dissociation curve shifts to the left when the affinity of haemoglobin for oxygen increases.

This left shift occurs under conditions such as low $pC{O}_2$, low $H^{+}$ concentration (which corresponds to high pH), low temperature, and low 2,3-DPG levels.

An increase in pH means a decrease in $H^{+}$ concentration, which favours the formation of oxyhaemoglobin and shifts the curve to the left.

Conversely, an increase in temperature, $pC{O}_2$, or DPG decreases the affinity of haemoglobin for oxygen and shifts the curve to the right.

Answer: pH