• Surface area?and?volume?are both very important factors in the?exchange of materials?in organisms
• The surface area refers to the?total area of the organism that is exposed to the external environment
• The volume refers to the?total internal volume of the organism?(total amount of space inside the organism)
• As the surface area and volume of an organism increase (and therefore the overall ‘size’ of the organism increases), the surface area : volume ratio?decreases
• This is because?volume increases much more rapidly than surface area as size increases

As size increases, the surface area : volume ratio decreases

• The surface area : volume ratio calculation differs for different shapes (these shapes can reflect different cells or organisms)

?????? Step 1: Rearrange the equation to find the radius

r²?= surface area/4π

?????? Step 2:?Sub in relevant figuresr²?= 10.12 ÷ 12.56 = 0.805

?????? Step 3: Find the square root of r²Square root of 0.805 = 0.897

?????? Step 4:?Find the diameter from the radiusD = 2r

2(0.897) = 1.794

?????? Step 5:?Round to three significant figures

1.79 mm