Does it need a membrane - diffusion (simple)
No
Diffusion
The passive movement of molecules from an area of high concentration gradient to an area of low concentration gradient
Factors that affect the rate of diffusion
Concentration gradient
Temperature
Surface area to volume ratio
Osmotic pressure
Pressure which must be exerted upon a solution to prevent the passage of distilled water into it across the semi permeable membrane
Turgor pressure
The internal pressure exerted on the walls of a cell by water.
Osmosis
Passive net movement of free water molecules from a hypotonic to a hypertonic solution across a semi permeable membrane