Answer: Determines the partial pressure that drives loading.
- A Determines the partial pressure that drives loading
- B Neutralises blood pH
- C Activates carbonic anhydrase
- D Forms carbamino compounds
Correct answer: A. Determines the partial pressure that drives loading
Explanation: The dissolved oxygen establishes the partial pressure (pO<sub>2</sub>) of blood, and it is this pressure gradient that governs binding and release of oxygen by haemoglobin.
The S-shaped (sigmoid) curve reflects cooperative binding between Hb's four O₂ sites; the Bohr effect shifts the whole curve to the right under conditions found in actively respiring tissue (more CO₂, more acid, more heat), making haemoglobin release oxygen more readily exactly where it's needed.
Concept context
The mechanics of breathing, lung volumes, gas transport in blood, the Bohr effect, and respiratory regulation.