Which two elements are most commonly found in biomolecules?

• A. Carbon and hydrogen
• B. Nitrogen and calcium
• C. Phosphorus and sulfur
• D. Oxygen and sodium

Answer: (A)

Verified step by step guidance

1. Understand the composition of biomolecules: Biomolecules are primarily composed of elements that form stable covalent bonds and are essential for life processes. These elements are typically found in organic compounds such as carbohydrates, lipids, proteins, and nucleic acids.
2. Recognize the most common elements in organic chemistry: Carbon (C) and hydrogen (H) are the backbone of organic molecules. Carbon's ability to form four covalent bonds makes it versatile for creating complex structures, while hydrogen is commonly bonded to carbon in hydrocarbons and other biomolecules.
3. Consider the role of oxygen (O): Oxygen is another key element in biomolecules, often found in functional groups such as hydroxyl (-OH), carbonyl (C=O), and carboxyl (-COOH). It plays a critical role in energy metabolism and structural components.
4. Evaluate the presence of nitrogen (N): Nitrogen is essential in biomolecules like amino acids (building blocks of proteins) and nucleotides (components of DNA and RNA). It is less abundant than carbon and hydrogen but still vital for life.
5. Exclude less common elements: Elements like calcium (Ca), phosphorus (P), sulfur (S), and sodium (Na) are important in specific biological functions (e.g., bone structure, signaling, and enzymatic activity) but are not as universally abundant in biomolecules as carbon and hydrogen.