Answer: Low pO2 and high pCO2.
- A High pO2 and low pCO2
- B Low pO2 and high pCO2
- C High pO2 and high pH
- D Low pCO2 and high pH
Correct answer: B. Low pO2 and high pCO2
Explanation: In actively respiring tissues the low partial pressure of oxygen, high pCO2, high H+ and higher temperature all favour dissociation of oxygen from 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.