The image shows a drawing of a cell membrane running horizontally. The area above the cell membrane is labeled Cytosol, and the area below the cell membrane is labeled Extracellular Fluid. On the left side of the membrane, an arrow that passes directly through the membrane connects a large group of white circles in the extracellular fluid to a small group of white circles in the cytosol. In the middle of the membrane, an arrow that passes between two large ovals that span the membrane connects a large group of black rectangles in the extracellular fluid to a small group of black rectangles in the cytosol. On the right side of the membrane, an arrow that passes through a large rectangle that spans the membrane connects a small group of black ovals in the extracellular fluid to a large group of black ovals in the cytosol.
Which of the following scientific questions is most relevant to the model represented in the figure above?