By which process, urea is formed in the liver cells?

Explanation

### Step-by-Step Solution:

1. **Identify the Process**: The process by which urea is formed in liver cells is known as the **Ornithine Cycle**, also referred to as the **Urea Cycle**.

2. **Location of the Process**: This cycle occurs primarily in the **liver cells**, which are also called **hepatocytes**. These cells contain all the necessary enzymes for the urea synthesis from ammonia.

3. **Conversion of Ammonia**: The primary function of the Ornithine Cycle is to convert **highly toxic ammonia** into **urea**, which is less toxic and can be safely excreted from the body.

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