Surface area to volume ratio
What Surface area to volume ratio means in Biology GCSE, as defined for AQA, OCR.
Definitions of Surface area to volume ratio
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Reference: OCR
As multicellular organisms increase in size, volume grows far faster than surface area, causing this ratio to decrease drastically.
In multicellular organisms this is small because they are large, so the surface area available is too small relative to the volume.
Compares the total external surface area of an organism with its volume, calculated by dividing surface area by volume.
A small cell has a large surface area relative to its volume, so diffusion alone can supply its needs quickly.
Dividing surface area by volume yields this ratio, which is conventionally simplified to the format N : 1.
A small surface-area-to-volume ratio makes simple diffusion too slow, so specialised surfaces are needed.
Topics that use Surface area to volume ratio
- Diffusion (AQA GCSE)
- Eukaryotes and prokaryotes (AQA GCSE)
- The challenges of size (OCR GCSE)
Related terms
- Exchange surfaces
- active transport of minerals
- arteries
- blood plasma
- boundary layer
- Cell membrane
- Cell wall
- compound measures
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