Which reactions are occurring in the blood within a capillary adjacent to an alveolus? 1. $\text{Hb} + 4\text{O}_2 \rightarrow \text{HbO}_8$ 2. $\text{H}_2\text{O} + \text{CO}_2 \rightarrow \text{H}_2\text{CO}_3$ 3. $\text{H}_2\text{CO}_3 \rightarrow \text{H}^+ + \text{HCO}_3^-$ Key: Hb = haemoglobin
- A1 and 2
- B1 only
- C2 and 3
- D2 only