Conversion of ammonia to urea is done by `…......................` Cycle -

Options

A. Ornithine cycle
B. Arginine cycle
C. Fumaric cycle
D. Citrulline cycle

Answer

To solve the question regarding the conversion of ammonia to urea, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ammonia Production**:
- Ammonia is produced as a waste product during nitrogen metabolism in the body. It is highly toxic and needs to be converted to a less toxic form for excretion.

**Hint**: Ammonia is a byproduct of protein metabolism and is toxic to the body.

2. **Need for Conversion**:
- Due to its toxicity, ammonia must be converted to urea, which is less toxic and requires less water for excretion. This conversion is crucial for maintaining nitrogen balance in the body.

**Hint**: Urea is safer for the body and is easier to excrete than ammonia.

3. **Identifying the Cycle**:
- The conversion of ammonia to urea occurs through a specific biochemical pathway known as the **Ornithine Cycle**, also referred to as the **Urea Cycle**.

**Hint**: Look for the cycle involved in nitrogen metabolism that specifically deals with urea formation.

4. **Location of the Cycle**:
- The Ornithine Cycle takes place in the mitochondria of liver cells. This is where the enzymes necessary for the conversion process are located.

**Hint**: Remember that the liver is the primary organ for detoxifying ammonia and converting it to urea.

5. **Final Answer**:
- Therefore, the cycle responsible for the conversion of ammonia to urea is the **Ornithine Cycle** or **Urea Cycle**.

**Hint**: The correct answer is a cycle that involves intermediates like arginine, fumarate, and citrulline.

### Conclusion:
The conversion of ammonia to urea is done by the **Ornithine Cycle** (Urea Cycle).