17. Biological membranes are made of lipids and proteins. Lipids were extracted from human red blood cells. The calculated total surface area of these red blood cells was found to be 36 . How much surface area would these lipids cover once they were spread across the surface of water? (Ignore the area occupied by proteins in the RBC membrane) (1) 72 (2) 36 (3)18 (4) 144 u