Which of the following is a primary function of lipids in biological systems?

• A. Transporting oxygen in the blood
• B. Encoding genetic information
• C. Catalyzing biochemical reactions
• D. Energy storage

Answer: (D)

Verified step by step guidance

1. Understand the role of lipids in biological systems: Lipids are a diverse group of molecules that include fats, oils, phospholipids, and steroids. Their primary functions include energy storage, structural components of cell membranes, and signaling molecules.
2. Compare the given options with the known functions of lipids: Lipids do not transport oxygen in the blood; this is primarily the role of hemoglobin, a protein. Lipids also do not encode genetic information; this is the role of nucleic acids like DNA and RNA. Lipids do not catalyze biochemical reactions; enzymes, which are proteins, perform this function.
3. Focus on energy storage: Lipids, particularly triglycerides, are highly efficient molecules for storing energy. They contain long hydrocarbon chains that can be broken down during metabolism to release large amounts of energy.
4. Relate energy storage to biological systems: Lipids are stored in adipose tissue in animals and serve as a long-term energy reserve. This is especially important for organisms that need energy during periods of fasting or hibernation.
5. Conclude that the correct answer is energy storage: Based on the comparison of functions and the biological role of lipids, the primary function of lipids in biological systems is energy storage.