Final answer:
Waxes and sphingolipids do not have a glycerol backbone.
Step-by-step explanation:
Waxes and sphingolipids do not have a glycerol backbone. Waxes are composed of long-chain fatty acids and alcohols, while sphingolipids have a sphingosine backbone. However, glycerol is found in glycerophospholipids and triglycerides.