To determine the identity of the biological molecule based on given elemental percentages, we follow these steps:
1. Examine the given percentages of elements:
- Carbon (C): 38%
- Nitrogen (N): 17%
- Phosphorus (P): 10%
- Oxygen (O): 31%
- Sulfur (S): 0%
- Hydrogen (H): 4%
2. Understand typical compositions in biological molecules:
- Proteins typically contain a significant amount of Carbon, Nitrogen, Oxygen, and Hydrogen. Proteins can also contain small amounts of Sulfur.
- Nucleic acids (DNA/RNA) contain a relatively high percentage of Phosphorus along with significant amounts of Carbon, Nitrogen, Oxygen, and Hydrogen.
- Carbohydrates are made primarily of Carbon, Oxygen, and Hydrogen, with only trace amounts of other elements.
- Lipids (fats) are predominantly composed of Carbon, Hydrogen, and Oxygen, usually with very low or negligible Nitrogen content.
3. Match percentages with molecule characteristics:
- The given composition has relatively high amounts of Nitrogen (17%) and Phosphorus (10%).
- Carbohydrates and lipids can be quickly excluded due to their low nitrogen and phosphorus content.
- The significant amount of Nitrogen suggests it's more than just nucleic acids, which balances the high Phosphorus content as well. Additionally, the Phosphorus amount suggests it’s not solely a simple protein, since typical proteins might have less Phosphorus.
- Proteins can contain Nitrogen and have small to negligible Sulfur content based on the composition.
4. Conclusion:
Given the element percentages, the molecule fits best with the composition of a protein. Proteins can indeed have the given mixture of 38% Carbon, 17% Nitrogen, 10% Phosphorus, 31% Oxygen, 0% Sulfur, and 4% Hydrogen.
Thus, the biological molecule is best described as a protein.
