Ornithine cycle performs

Options

A. ATP synthesis
B. Urea formation in spleen
C. Urea formation in liver
D. Urine formation in liver

Answer

### 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 in the liver. Its primary function is to convert excess nitrogen from amino acid metabolism into urea for excretion.

2. **Identifying the Purpose of the Cycle**: The main purpose of the Ornithine cycle is to detoxify ammonia, which is a byproduct of amino acid breakdown. Ammonia is toxic to the body, so it must be converted into a less harmful substance, which is urea.

3. **Location of the Cycle**: The Ornithine cycle takes place in the liver. This is crucial as the liver is the organ responsible for processing nitrogenous waste.

4. **Process of Urea Formation**: The cycle involves several steps where ammonia is combined with carbon dioxide and other molecules to ultimately produce urea. This process includes the conversion of ammonia (NH3) into urea ((NH2)2CO), which is then released into the bloodstream.

5. **Transport and Excretion**: Once urea is formed in the liver, it is transported to the kidneys through the bloodstream. The kidneys filter the blood, allowing urea to be excreted from the body through urine.

6. **Conclusion**: Based on the above information, the correct answer to the question "Ornithine cycle performs" is that it is responsible for "urea formation in the liver."

### Final Answer:
The Ornithine cycle performs urea formation in the liver.

---