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GCSE Biology · key term
The amount of three-dimensional space occupied by an object, measured in cubed units such as cm³.
Used by AQA, Edexcel and OCR
Specification 4.1.3.1 · Paper 1
Revise: Surface Area to Volume Ratio and Exchange SystemsSurface area measures how much exposed surface is available for exchange, whereas volume measures how much space is inside. In biological models, volume can represent the amount of living material that must be supplied and have its waste products removed.
Specification 8.2 · Paper 2
The space an object occupies, measured in cubed units such as cm³.
Use the same length unit throughout before calculating or comparing ratios. Remember that area has squared units and volume has cubed units.
Simplify surface area : volume in the same way as any other ratio. For example, simplifies to .
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An exchange surface is where substances enter or leave an organism. Its area limits how much surface is available for exchange, while the organism's volume represents how much living material may need supplying. As an organism gets larger, its volume grows faster than its surface area.
Specification B2.2a · Paper 1 (Foundation), Paper 3 (Higher)
Revise: Exchange surfacesA single-celled organism has its entire cell membrane in contact with its environment. It has a large amount of membrane surface compared with its small volume, and no part of the cell is far from that membrane. Diffusion across the cell surface can therefore meet the cell's needs.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
The amount of space occupied by an organism or structure; it is related to how much living tissue needs supplies and produces waste.
Revise: Exchange SurfacesSurface area describes how much boundary is available for exchange; volume is related to how much living tissue needs supplies and produces waste. Comparing them gives the surface area:volume ratio.
The amount of three-dimensional space occupied by an object.
Do not confuse total surface area with surface area to volume ratio. A larger organism can have a greater total surface area but a smaller surface area to volume ratio.