Give the definition of diffusion and write its properties.

(N/A) $\Rightarrow$ Definition: The movement of molecules of any substance from a region of higher concentration to a region of lower concentration is called diffusion. Molecules move in a random fashion.
$\Rightarrow$ Properties:
$\bullet$ Movement by diffusion is passive.
$\bullet$ It may occur from one part of the cell to another,or from cell to cell.
$\bullet$ This movement occurs over short distances.
$\bullet$ It can occur from the intercellular spaces of a leaf to the outside environment.
$\bullet$ No energy expenditure takes place during diffusion.
$\bullet$ Diffusion is a slow process and is not dependent on a 'living system'.
$\bullet$ Diffusion is most obvious in gases and liquids.
$\bullet$ Diffusion of solid substances is also possible.
$\bullet$ Diffusion is very important to plants since it is the only means for gaseous movement within the plant body.
$\bullet$ Diffusion rates are affected by the concentration gradient,the permeability of the membrane separating them,temperature,and pressure.