This takes place when molecules diffuse across the cell membrane by travelling through specific transport ... not require a supply of energy because diffusion is a spontaneous process.

All cells have an outer plasma membrane ... can also pass through membranes, but they do so more slowly. On the other hand, cell membranes restrict diffusion of highly charged molecules, such ...

the diffusion of water. In the diagram above solution two gains water faster than it loses sugar. This is because the selectively permeable membrane lets water molecules pass through much more ...

These discontinuities can prevent, or temporarily restrict, the free diffusion of membrane molecules. Figure 1: Fluorescence recovery after photobleaching (FRAP). Unrestricted diffusion of a ...