The first formed nitrogenous waste of vertebrates is

Options

A. `NH_(2)`
B. Urea
C. `NH_(3)`
D. `NH_(4)`

Answer

To solve the question "The first formed nitrogenous waste of vertebrates is," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nitrogenous Waste**:
- Nitrogenous waste is a byproduct of the metabolism of proteins and nucleic acids. When proteins and amino acids are broken down, they release nitrogen.

2. **Identifying Nitrogenous Compounds**:
- The primary nitrogenous compounds involved in metabolism include amino acids, purines, and pyrimidines. These compounds contain nitrogen and are metabolized to release ammonia.

3. **Formation of Ammonia**:
- During the catabolism (breakdown) of these nitrogenous compounds, the first nitrogenous waste that is produced is ammonia (NH3). This is because amino groups (-NH2) from amino acids are converted into ammonia.

4. **Conversion to Urea**:
- Ammonia is toxic, so it is transported to the liver, where it enters the urea cycle. In this cycle, ammonia is converted into urea, which is less toxic and can be safely excreted by the kidneys.

5. **Conclusion**:
- The question asks for the first formed nitrogenous waste. Since ammonia is the initial product formed from the breakdown of nitrogenous biomolecules, the answer is ammonia (NH3).

### Final Answer:
The first formed nitrogenous waste of vertebrates is **NH3 (ammonia)**.

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