How do substances move across a selectively permeable membrane?
A selectively permeable membrane is a membrane that allows some substances to pass through easily, while other substances pass through very slowly or not at all. All cell membranes, including the plasma membrane, are selectively permeable. In the exercise below, you will learn about 2 types of diffusion across selectively permeable membranes: • Simple diffusion refers to diffusion of substances without the help of transport proteins. • Facilitated diffusion refers to diffusion of substances with the help of transport proteins.
