AQA AS Biology

Revision Notes

3.1.1 Surface Area to Volume Ratio

Surface Area to Volume Ratio

  • 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

11. Principles of surface area _ volume, downloadable AS & A Level Biology revision notes

As size increases, the surface area : volume ratio decreases

  • Calculating SA_V ratios, downloadable AS & A Level Biology revision notes

 

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

Exam Tip

You are expected to be able to calculate the SA:V ratio for a cube, cuboid or cylinder and explain how the increasing size of an organism affects the SA:V ratio.

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