a Cut jelly cubes in different sizes – 2 cm x 2 cm, 1 cm x 2cm and 0.9 cm x 1cm

b Place the cubes in a beaker and cover with the Hydrochloric acid.

c Time how long it takes for the acid to change the colour of the indicator in each jelly block.  (calculate diffusion time – 447sec, 380sec, 345sec)

 d Calculate volume ratio and surface area:

SA= 12,8cm2         SA=7,6sm2        SA=4,08cm2

V=2,4cm3              V=1,2cm3            V=0,54cm3


As surface area increases, time taken decreases. The bigger the surface area, the more time it takes to diffuse.


Surface area to volume ration is important in the limitation of cell size.


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