Which of the following is an accurate statement regarding biological membrane lipids?

1. Cholesterol is a steroid lipid with two fatty acid chains
2. Phosphatidylcholine is less abundant in biological membranes than phosphatidylinositol-4,5-biphosphate
3. Phosphatidylserine has a net positive charge
4. Plasma membrane glycolipids are preferentially located in the extracellular-facing leaflet of the lipid bilayer
5. Sphingomyelin is a phospholipid that is derived from glycerol