Which lipid type has a glycerol backbone with three fatty acids?

• A. Triglycerides
• B. Phospholipids
• C. Steroids
• D. Carotenoids

Answer: (A)

Triglycerides are the lipid type with a glycerol backbone bearing three fatty acids. Glycerol has three hydroxyl groups, and each can form an ester bond with a fatty acid; when all three sites are esterified, you get a triacylglycerol. This structure makes triglycerides highly nonpolar and excellent for long‑term energy storage in adipose tissue. In contrast, phospholipids also use a glycerol backbone but have only two fatty acids and a phosphate-containing head group, forming cellular membranes. Steroids are built from four fused hydrocarbon rings, not glycerol. Carotenoids are long isoprenoid pigments without a glycerol backbone.