Answer: Binds CO 2 and H + more readily.
- A Binds oxygen more strongly
- B Blocks carbonic anhydrase
- C Prevents the chloride shift
- D Binds CO<sub>2</sub> and H<sup>+</sup> more readily
Correct answer: D. Binds CO<sub>2</sub> and H<sup>+</sup> more readily
Explanation: Deoxygenated (reduced) haemoglobin has a greater capacity to bind H<sup>+</sup> and form carbamino compounds, so venous blood transports more carbon dioxide.
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.