Four possibilites for the transport of carbon dioxide from the body cells to the lungs are listed below which possibility does no exist ?

Options

A. bound to the ferro ions of haemoglobin in erythrocytes
B. As a hydrocarbonate ion in the buffering system of the blood
C. As a hydrocarbonate ion in the buffering system of the blood
D. dissolved in blood plasma and in erythrocyte cytoplasm

Answer

To determine which possibility for the transport of carbon dioxide from body cells to the lungs does not exist, we need to analyze the four options provided.

### Step-by-Step Solution:

1. **Understanding Carbon Dioxide Transport**:
Carbon dioxide (CO2) is a waste product produced by cells during metabolism. It needs to be transported from the body cells to the lungs for exhalation.

2. **Identifying the Transport Methods**:
There are several known methods for the transport of carbon dioxide in the blood:
- **Bound to Hemoglobin**: CO2 can bind to hemoglobin in red blood cells (RBCs) to form carbaminohemoglobin. However, it does not bind to the iron (ferroions) of hemoglobin.
- **As Bicarbonate Ions**: A significant portion of CO2 is converted into bicarbonate ions (HCO3-) in the blood, which helps in buffering.
- **Dissolved in Plasma**: Some CO2 is transported dissolved directly in the blood plasma.

3. **Evaluating the Statements**:
- **Statement 1**: "Carbon dioxide is bound to the ferroions of hemoglobin."
- This is incorrect because CO2 binds to the amino groups of hemoglobin, not the iron.
- **Statement 2**: "Carbon dioxide is transported as bicarbonate ions."
- This is correct as CO2 is converted to bicarbonate in the blood.
- **Statement 3**: "Carbon dioxide is dissolved in the blood plasma."
- This is also correct as CO2 can be transported in a dissolved state.
- **Statement 4**: (Assuming a fourth statement is similar to the above or another method) needs to be evaluated based on the context.

4. **Conclusion**:
The first statement is the one that does not exist as a method for transporting carbon dioxide since CO2 does not bind to the iron of hemoglobin.

### Final Answer:
The possibility that does not exist is: **"Carbon dioxide is bound to the ferroions of hemoglobin."**