Assertion : Carbonic anhydrase is present in the erythrocytes.
Reason : In erythrocytes the carbon dioxide combine with water and is transported.

Options

A. Statement A is correct and is responsible for statement B
B. Statement A is not correct but Statement B is correct
C. Both Statement A and B are wrong
D. Statement A is correct and statement B is wrong.

Answer

To solve the question regarding the assertion and reason related to carbonic anhydrase and its role in erythrocytes, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understand the Assertion**: The assertion states that "Carbonic anhydrase is present in the erythrocytes."
- **Explanation**: Carbonic anhydrase is indeed an enzyme that catalyzes the conversion of carbon dioxide and water into bicarbonate and protons. This enzyme is found in red blood cells (erythrocytes), which confirms that the assertion is true.

2. **Understand the Reason**: The reason states that "In erythrocytes, carbon dioxide combines with water and is transported."
- **Explanation**: In the erythrocytes, carbon dioxide does combine with water to form bicarbonate (HCO3-) and protons (H+), which are then transported in the blood. This reaction is facilitated by carbonic anhydrase, confirming that the reason is also true.

3. **Evaluate the Relationship**: Now, we need to determine if the assertion is responsible for the reason.
- **Explanation**: Since carbonic anhydrase is responsible for the reaction that combines carbon dioxide with water in erythrocytes, the assertion (that carbonic anhydrase is present) does support the reason (that carbon dioxide combines with water and is transported).

4. **Conclusion**: Both the assertion and the reason are true, and the assertion is responsible for the reason.
- **Final Answer**: The correct option is: "Statement A is correct and is responsible for statement B."