Passive transport
Passive transport means moving biochemicals and atomic or molecular substances across the cell membrane. Unlike active transport, this process does not involve chemical energy. The four main kinds of passive transport are diffusion, facilitated diffusion, filtration and osmosis.
Osmosis
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/76/Osmotic_pressure_on_blood_cells_diagram.svg/249px-Osmotic_pressure_on_blood_cells_diagram.svg.png)
Osmosis is the diffusion of water molecules across a selectively permeable membrane. The net movement of water molecules through a partially permeable membrane from a solution of high water potential to an area of low water potential. A cell with a less negative water potential will draw in water but this depends on other factors as well such as solute potential (pressure in the cell e.g. solute molecules) and pressure potential (external pressure e.g. cell wall).
See also
[[Category:Cellular processes