Ornithine cycle is related to

Options

A. Respiration
B. Excretion
C. Digestion
D. Nutrition

Answer

### Step-by-Step Solution:

1. **Understanding the Ornithine Cycle**: The Ornithine cycle, also known as the urea cycle, is a biochemical process that occurs in the liver. It is responsible for converting excess ammonia, which is toxic, into urea, which can be safely excreted from the body.

2. **Role of Amino Acids**: When proteins are broken down in the body, they release amino acids. Excess amino acids undergo a process called deamination, where the amino group (NH2) is removed. This process is crucial because the removal of the amino group produces ammonia, a toxic substance.

3. **Formation of Ammonium Ion**: During deamination, the amino group is converted into ammonium ions (NH4+). This transformation occurs primarily in the liver, where the ammonia is then processed further.

4. **Conversion to Urea**: The ammonium ions enter the Ornithine cycle, where they are converted into urea. Urea is much less toxic than ammonia and can be safely transported in the bloodstream.

5. **Excretion Process**: Once urea is formed, it is released into the bloodstream and transported to the kidneys. The kidneys filter the blood, and urea is excreted from the body through urine.

6. **Conclusion**: Thus, the Ornithine cycle is primarily related to the excretion of nitrogenous waste (urea) from the body, making it a crucial process for maintaining nitrogen balance and detoxifying ammonia.

### Final Answer:
The Ornithine cycle is related to **excretion**.

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