While diffusion transports materials across membranes and within cells, osmosis transports only water across a membrane. The semipermeable membrane. Cell Diffusion H 2 O, CO 2, & O 2 are among the few Osmosis : Diffusion of H 2 O across a semi-permeable membrane As the concentration. suspect that the plasma membranes of erythrocytes and other cell types.
Osmosis cell membrane Video