Which of the following substances are classified as lipids?

Lipids are a diverse group of hydrophobic organic compounds that play crucial roles in biological systems, primarily in cell membranes, energy storage, and signaling. The substances classified as lipids include fats, oils, waxes, and steroids, which all share common characteristics like being insoluble in water and soluble in nonpolar solvents.

Fats and oils, also known as triglycerides, are composed of glycerol and fatty acids and serve as major energy storage molecules. Waxes, which are long-chain fatty acids esterified to long-chain alcohols, are important for protective coatings in plants and animals. Steroids, which include hormones such as cholesterol, have a characteristic structure that allows them to function effectively in cellular signaling and membrane structure.

The other options listed do not fall under the lipid category. Proteins and carbohydrates are fundamentally different classes of biomolecules with distinct structures and functions. Amino acids are the building blocks of proteins, and nucleic acids (like DNA and RNA) are involved in genetic information storage and transfer, making them separate from lipid classification. Simple sugars are carbohydrates and serve as a primary energy source but do not possess the properties that define lipids. Therefore, the substances classified as lipids are specifically fats, oils, waxes,