diffusion/osmosis (bio chap 2 sec 3)

• diffusion is the net movement of particles from a region of high concentration to a region of low concentration, down a concentration gradient
• the factors that affect the rate of diffusion are surface area-to-volume ratio, diffusion distance and concentration gradient
• as a cell grows, the rate of movement of substances across the cell will decrease
• some cell have specifically adapted to absorb substances such as root hair cells where they have long narrow protrusions to increase the surface area-to-volume ratio of the cell membrane.