Cell membranes protect and organize cells. All cells have an outer plasma membrane that regulates ... On the other hand, cell membranes restrict diffusion of highly charged molecules, such as ...

This does not require a supply of energy because diffusion is a spontaneous process. This occurs when molecules are moved across the cell membrane from an area where they are at a low ...

Diffusion is the movement of particles from ... and is one of the ways substances can move across the cell membrane, into or out of the cell. Products of digestion, dissolved in water, can pass ...