What is the effect of an increase in temperature on the oxygen dissociation curve?

• A. Shifts left
• B. Shifts right
• C. No change
• D. Denatures the bond between oxygen and haemoglobin

Answer: (B)

An increase in temperature lowers hemoglobin’s affinity for oxygen, so the oxygen-hemoglobin dissociation curve shifts to the right. This means that at the same partial pressure of oxygen, hemoglobin is less saturated, and the P50 (the PO2 at 50% saturation) increases. The body benefits during activity because warmer tissues need more oxygen, and the rightward shift facilitates greater oxygen delivery where it’s needed. A leftward shift would occur with cooler temperatures or higher pH, where Hb holds onto O2 more tightly. The idea of denaturing the bond isn’t how this works under normal physiological temperature changes; the curve shifts without denaturation.