Solution

• E Gorter and F Grendel made a breakthrough by examining the surface area of lipids and concluded that the lipid surface surrounding cells must be of two layers in the year 1925. Their experiment involved extracting lipids from red blood cells and then spreading them out on a water surface to form a monolayer. •They then measured the area of the monolayer and found that it was twice the area of the surface area of the red blood cells. • This led them to conclude that the lipid bilayer model of the cell membrane must be correct. • Gorter and Grendel's work was a major breakthrough in the understanding of cell structure and function. • It helped to establish the lipid bilayer model of the cell membrane, which is still the accepted model today.