2.15 understand the factors that affect the rate of movement of substances into and out of cells, to include the effects of surface area to volume ratio, temperature and concentration gradient

Surface area
with a larger surface area- molecules have more surfaces through which to diffuse, this increases the rate of moment

Temperature
Increased temperature means increased kinetic energy- this will mean molecules collide with the cell membrane more often making movement through it more likely

Concentration gradient
This is the difference between the concentration inside and outside of the cell. The bigger the difference is the more opportunity molecules have of diffusing.