Diffusion is a process where by the net movement of molecules move from an area of higher molecules concentration to lower molecules concentration. This process will stop once all the molecules become evenly dispersed throughout the object. Molecules never stop moving. They are moving all the time. The factors that determine the rate of diffusion are:1)Temperature,2)Size of molecules and 3)The steepness of the concentration gradient. Eg: Nutrients moving into the cell and waste moving out of the cell. There are 3 types of passive transport. It is called passive because it requires no energy from the cell to carry the substance across the membrane.
