Apart from carbon, hydrogen and oxygen the most prevalent element in living organisms

Options

A. Phosphorus
B. Nitrogen
C. Calcium
D. Iron

Answer

To answer the question "Apart from carbon, hydrogen, and oxygen, what is the most prevalent element in living organisms?", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Essential Elements**: Begin by recognizing that carbon, hydrogen, and oxygen are the most prevalent elements in living organisms. These elements are fundamental for the formation of biomolecules such as carbohydrates, proteins, and nucleic acids.

2. **Consider Other Elements**: Next, we need to look at other elements that are also important in living organisms. The options given are phosphorus, nitrogen, calcium, and iron.

3. **Evaluate Each Option**:
- **Phosphorus**: While phosphorus is important for nucleic acids and energy transfer (ATP), it is not as prevalent as nitrogen.
- **Nitrogen**: Nitrogen is a key component of amino acids, which are the building blocks of proteins. Since proteins are crucial for many biological functions, nitrogen is highly prevalent in living organisms.
- **Calcium**: Calcium is important for bone structure and various cellular functions, but it is not as abundant as nitrogen.
- **Iron**: Iron is essential for oxygen transport in the blood (hemoglobin) and other functions, but it is present in much smaller amounts compared to nitrogen.

4. **Conclusion**: After evaluating all options, nitrogen stands out as the most prevalent element apart from carbon, hydrogen, and oxygen. Therefore, the correct answer is **option 2: nitrogen**.

### Final Answer:
The most prevalent element in living organisms, apart from carbon, hydrogen, and oxygen, is **nitrogen**.

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