Which of the following is a function of lipids? A) Store energy B) Serve as the primary structural component of DNA C) Transport oxygen D) Break down proteins

The correct answer is: **A) Store energy** **Explanation:** Lipids play several vital roles in living organisms, including: - **Storing Energy:** Lipids, particularly triglycerides, are excellent for energy storage. They can store more energy per gram than carbohydrates or proteins, making them efficient for long-term energy reserves. - **Structural Components:** Phospholipids and cholesterol are essential components of cell membranes, providing structural integrity and fluidity. - **Insulation and Protection:** Lipids help insulate the body and protect vital organs. - **Signaling Molecules:** Some lipids act as hormones and signaling molecules, influencing various physiological processes. The other options are functions of different biomolecules: - **B) Serve as the primary structural component of DNA:** This is incorrect because DNA's primary structural components are nucleotides, which consist of sugars, phosphates, and nitrogenous bases, not lipids. - **C) Transport oxygen:** This is a function of hemoglobin, a protein found in red blood cells. - **D) Break down proteins:** Protein digestion is carried out by enzymes like proteases, which are themselves proteins. **Therefore, option A accurately describes a function of lipids.**