Which macromolecules form important parts of bones, muscles, blood, enzymes, some hormones, and cell membranes?

• A. Carbohydrates
• B. Lipids
• C. Nucleic acids
• D. Proteins

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the role of macromolecules in the body. Macromolecules are large molecules essential for various biological functions, including structural support, energy storage, and catalysis of biochemical reactions.
2. Step 2: Analyze the options provided: Carbohydrates, Lipids, Nucleic acids, and Proteins. Each of these macromolecules has distinct functions in the body. For example, carbohydrates primarily serve as energy sources, lipids are involved in energy storage and membrane structure, and nucleic acids store genetic information.
3. Step 3: Focus on the functions mentioned in the problem: bones, muscles, blood, enzymes, some hormones, and cell membranes. Proteins are the macromolecules that play a central role in these areas. For instance, collagen (a protein) is a key component of bones, actin and myosin (proteins) are essential for muscle contraction, hemoglobin (a protein) transports oxygen in blood, enzymes are proteins that catalyze biochemical reactions, and some hormones like insulin are proteins.
4. Step 4: Understand why the other macromolecules are not the correct answer. Carbohydrates are primarily involved in energy metabolism, lipids contribute to energy storage and membrane structure but are not directly involved in the functions listed, and nucleic acids are responsible for genetic information storage and transmission.
5. Step 5: Conclude that proteins are the correct answer because they are versatile macromolecules involved in structural, functional, and regulatory roles in the body, aligning with the functions described in the problem.