The presence of arginase confirms that

Options

A. Arginine is synthesised
B. Ammonia is formed
C. Arginine is being converted into ornithine
D. Arginine is being converted into citrulline

Answer

To answer the question "The presence of arginase confirms that," we need to understand the role of arginase in the urea cycle and its implications in mammalian metabolism.

### Step-by-Step Solution:

1. **Understanding the Urea Cycle**:
- The urea cycle is a series of biochemical reactions that convert ammonia, which is toxic at high levels, into urea, which can be safely excreted. This cycle primarily occurs in the liver.

2. **Role of Arginase**:
- Arginase is an enzyme that catalyzes the final step of the urea cycle. It converts arginine into urea and ornithine. This step is crucial because it helps in the removal of excess nitrogen from the body.

3. **Location of the Urea Cycle**:
- The urea cycle consists of several steps. The first two steps occur in the mitochondria, while the remaining steps, including the action of arginase, occur in the cytosol.

4. **Function of Arginine**:
- In the last step of the urea cycle, arginine is cleaved by arginase to produce urea and ornithine. The ornithine can then re-enter the mitochondria to continue the cycle.

5. **Conclusion**:
- Therefore, the presence of arginase confirms that arginine is being converted into urea and ornithine, indicating that the urea cycle is active. This also implies that the organism is effectively processing nitrogenous waste.

### Final Answer:
The presence of arginase confirms that arginine is reconverted into urea and ornithine.

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