(3) the concentration of the substance is greater outside the cell than inside
Explanation;
-When a substance is of low molecular weight and has a higher concentration of the substance outside the cell as opposed to inside the cell then it is most likely to diffuse into a cell.
-Diffusion involves the movement of molecules from a region of high concentration to a region of low concentration, therefore if molecules are highly concentrated outside the cell then they are likely to move into the cell. Additionally, the size or the molecular weight of the molecules determines whether they will move into to the cell as the cell membrane only allows movement of materials in or out of the cell selectively.
