Question

what are cell membranes mostly made up of? lipids proteins nucleic acid carbohydrates

Explanation:

Cell membranes are primarily composed of lipids, specifically phospholipids which form a bilayer. Proteins are also present but lipids are the main component. Nucleic acids are for genetic information storage and not a major part of cell - membrane structure. Carbohydrates are often attached to lipids or proteins on the cell - membrane surface but are not the main constituent.

Answer:

Lipids