Select the incorrect statement.

Options

A. Every 100 ml of deoxygenated blood, delivers approximately 4 ml of `CO_(2)` to the alveoli.
B. Carbonic anhydrase is present in very high concentration in RBC.
C. High `Pco_(2)` and low `pO_(2)` in tissue help in binding of carbon dioxide.
D. `CO_(2)` is carried in haemoglobin as carboxyhemoglobin.

Answer

To solve the question of selecting the incorrect statement, we will analyze each of the provided statements one by one.

### Step-by-Step Solution:

1. **Statement 1**: "Every 100 milliliters of deoxygenated blood delivers approximately 4 milliliters of carbon dioxide to the alveoli."
- This statement is **true**. Deoxygenated blood does indeed transport carbon dioxide to the alveoli for exhalation.

2. **Statement 2**: "Carbonic anhydrase is present in very high concentration in red blood cells."
- This statement is also **true**. Carbonic anhydrase is an enzyme found in high concentrations in red blood cells, where it plays a crucial role in the conversion of carbon dioxide and water into carbonic acid.

3. **Statement 3**: "High partial pressure of carbon dioxide and low partial pressure of oxygen in tissue help in binding of carbon dioxide."
- This statement is **true**. In tissues, the high partial pressure of carbon dioxide and low partial pressure of oxygen facilitate the binding of carbon dioxide to hemoglobin.

4. **Statement 4**: "Carbon dioxide is carried in hemoglobin as carboxyhemoglobin."
- This statement is **incorrect**. Carbon dioxide is primarily carried in hemoglobin as carbaminohemoglobin, not carboxyhemoglobin. Carboxyhemoglobin is formed when carbon monoxide binds to hemoglobin, which is a different process.

### Conclusion:
The incorrect statement is: **"Carbon dioxide is carried in hemoglobin as carboxyhemoglobin."**

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