in which of the following forms ,CO_2 is not transported in the blood?

Options

A. carbaminohaemoglobin
B. in dissolved state through plasma
C. carboxyhaemoglobin
D. Bicarbonates

Answer

To determine in which form CO2 is not transported in the blood, we will analyze the options provided.

**Step 1: Understanding CO2 Transport Forms**
CO2 is transported in the blood in three main forms:
1. **Dissolved in Plasma**: A small percentage of CO2 is transported dissolved directly in the plasma.
2. **Carbo-Amino-Hemoglobin**: CO2 can bind to hemoglobin to form a complex known as carbo-amino-hemoglobin. This is a significant method of CO2 transport.
3. **Bicarbonate Ions (HCO3-)**: The majority of CO2 is converted into bicarbonate ions in the blood, which helps in maintaining the acid-base balance.

**Step 2: Analyzing the Options**
- **Carbo-Amino-Hemoglobin**: This form does transport CO2 as it binds with hemoglobin.
- **Dissolved State in Plasma**: CO2 can be transported in this form, although it is a smaller percentage.
- **Carboxyhemoglobin**: This is a complex formed when hemoglobin binds with carbon monoxide (CO), not CO2. Therefore, CO2 is not transported in this form.
- **Bicarbonate**: This is a primary form of CO2 transport in the blood.

**Step 3: Conclusion**
Based on the analysis, the form in which CO2 is not transported in the blood is **Carboxyhemoglobin**.

**Final Answer: Carboxyhemoglobin**

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