particles move around randomly and end up evenly spaced.
the gradual movement of particles from places of HIGH CONCENTRATION to areas of LOW CONCENTRATION
occours in LIQUIDS and GASSES only because particles are able to move about randomly in these substances.
DIFFFUSSION THROUGH CELL MEMBRANES
cell membranes hold the cell together while letting small molecules such as oxygen, glucose, ameno acids and water into the cell.
dissloved substances can move in and out of cells by diffusion. big molecules such as starch and proteins are too large to pass through and are usually in larger chains.