Much of `CO_2` is transported by the blood as

Options

A. Dissolved in plasma
B. Bicarbonate
C. Attached to haemoglobin
D. Carbonate

Answer

To answer the question "Much of CO2 is transported by the blood as," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding CO2 Transport**: Carbon dioxide (CO2) is a waste product of cellular respiration and needs to be transported from the tissues to the lungs for exhalation.

2. **Forms of CO2 in Blood**: CO2 is transported in the blood in three main forms:
- **Bicarbonate ions (HCO3-)**: This is the primary form in which CO2 is transported.
- **Carbamino compounds**: CO2 can bind to hemoglobin and other proteins, forming carbamino compounds.
- **Dissolved CO2**: A small amount of CO2 is transported dissolved directly in the plasma.

3. **Percentage of CO2 Transported**:
- Approximately **70%** of CO2 is transported as bicarbonate ions.
- About **23%** is transported as carbamino compounds.
- Roughly **7%** is dissolved in the plasma.

4. **Conclusion**: Since the question asks for the form in which much of the CO2 is transported, we can conclude that the majority of CO2 is transported as bicarbonate ions.

5. **Final Answer**: Much of CO2 is transported by the blood as **bicarbonates**.