Which of the following correctly lists functions of proteins in biological systems?

• A. Cellulose formation, oxygen production, and water transport
• B. Energy storage, genetic information storage, and insulation
• C. Hormone synthesis, DNA replication, and lipid digestion
• D. Enzyme catalysis, structural support, transport, and immune defense

Answer: (D)

Verified step by step guidance

1. Step 1: Begin by understanding the role of proteins in biological systems. Proteins are macromolecules composed of amino acids and are essential for various cellular functions.
2. Step 2: Analyze the options provided in the problem. Evaluate each function listed to determine if it aligns with known protein functions. For example, cellulose formation is a carbohydrate-related process, not a protein function.
3. Step 3: Recall the major functions of proteins, which include enzyme catalysis (speeding up biochemical reactions), structural support (e.g., collagen in connective tissues), transport (e.g., hemoglobin transporting oxygen), and immune defense (e.g., antibodies protecting against pathogens).
4. Step 4: Compare the correct answer provided ('Enzyme catalysis, structural support, transport, and immune defense') with the other options. Eliminate incorrect options based on your understanding of protein functions.
5. Step 5: Conclude that the correct answer aligns with the known functions of proteins in biological systems, as proteins are involved in catalysis, structural roles, transport, and immune defense, but not in cellulose formation, genetic information storage, or insulation.