Which element is always present in proteins but never in simple carbohydrates or triglycerides?
- A. Phosphorus
- B. Nitrogen
- C. Magnesium
- D. Calcium
Explanation
Every amino acid carries an amino group, so nitrogen is a constant feature of proteins, and sulphur also appears in some. Simple carbohydrates and triglycerides contain only carbon, hydrogen and oxygen, and phosphorus is confined to compounds such as phospholipids and nucleic acids.
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