The two metabolic end products that are utilised during the ornithine cycle are :

Options

A. `CO_2` and urea
B. `CO_2 ` and ammonia
C. ammonia and urea
D. ammonia and uric acid

Explanation

**Step-by-Step Solution:**

1. **Understanding the Ornithine Cycle**: The ornithine cycle, also known as the urea cycle, is a series of biochemical reactions that occur primarily in the liver. Its main function is to convert ammonia, which is toxic, into urea, which can be safely excreted from the body.

2. **Identifying the Metabolic End Products**: In the ornithine cycle, the two key metabolic end products that are utilized are ammonia (NH₃) and carbon dioxide (CO₂).

3. **Role of Ammonia and Carbon Dioxide**:
- Ammonia is produced during the breakdown of amino acids and is highly toxic.
- Carbon dioxide is a byproduct of cellular respiration and is also involved in the urea cycle.

4. **The Reaction Process**:
- Ammonia combines with carbon dioxide to form carbamoyl phosphate, which is the first step of the urea cycle.
- This reaction is catalyzed by the enzyme carbamoyl phosphate synthetase.

5. **Final Product**: The end product of the ornithine cycle is urea, which is then transported to the kidneys for excretion.

**Conclusion**: The two metabolic end products utilized during the ornithine cycle are ammonia (NH₃) and carbon dioxide (CO₂).

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