Triglycerides are a type of what biomolecule?

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

Answer: (D)

Triglycerides are a type of lipid, a class of biomolecules that are hydrophobic and used mainly for long-term energy storage and insulation. Their structure—glycerol backbone with three fatty acids attached via ester bonds—gives them nonpolar, water-insoluble properties typical of lipids. This distinguishes them from nucleic acids, which store genetic information in nucleotides; from proteins, which are made of amino acids and perform diverse functions; and from carbohydrates, which include sugars and starches that provide quick energy and have more polar, water-soluble characteristics. The high energy density of triglycerides and their role as stored fat reflect why the correct category is lipids.