Which three elements are found in all biological macromolecules?

• A. Iron, magnesium, and chlorine
• B. Carbon, hydrogen, and oxygen
• C. Calcium, potassium, and sodium
• D. Nitrogen, phosphorus, and sulfur

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the concept of biological macromolecules. Biological macromolecules are large molecules essential for life, including carbohydrates, lipids, proteins, and nucleic acids. These molecules are primarily composed of certain key elements.
2. Step 2: Recall the primary elements found in biological macromolecules. Carbon (C), hydrogen (H), and oxygen (O) are the foundational elements present in all macromolecules because they form the backbone of organic chemistry and are involved in the structure and function of these molecules.
3. Step 3: Analyze the options provided. Iron, magnesium, and chlorine are trace elements and not universally found in all macromolecules. Calcium, potassium, and sodium are important for cellular functions but are not structural components of macromolecules. Nitrogen, phosphorus, and sulfur are found in specific macromolecules (e.g., proteins and nucleic acids) but not universally in all.
4. Step 4: Recognize that carbon, hydrogen, and oxygen are the correct answer because they are universally present in carbohydrates, lipids, proteins, and nucleic acids, forming the structural framework of these molecules.
5. Step 5: Conclude that understanding the universal presence of carbon, hydrogen, and oxygen in biological macromolecules is essential for grasping the basics of biochemistry and molecular biology.