Surface Area to Volume Ratio (AQA A-Level Biology): Flashcards
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Practise the cards
10 cards from this deck
Materials organisms exchange with environment
Materials organisms exchange with environment
Nutrients, O₂, water in; waste (CO₂, urea) out
How SA increases vs volume as object grows
How SA increases vs volume as object grows
SA increases as , volume as
SA:V ratio change as organism size increases
SA:V ratio change as organism size increases
SA:V ratio decreases rapidly
Why small organisms can rely on simple diffusion
Why small organisms can rely on simple diffusion
High SA:V ratio & short diffusion distances
Problem large organisms face with low SA:V ratio
Problem large organisms face with low SA:V ratio
Diffusion distances to centre too great, cells would die
3 solutions large organisms evolved for exchange
3 solutions large organisms evolved for exchange
Flattened shapes, specialised surfaces, transport systems
Exchange surface feature: surface area
Exchange surface feature: surface area
Large surface area relative to volume
Exchange surface feature: wall thickness
Exchange surface feature: wall thickness
Very thin walls, often just one cell thick
Exchange surface feature: permeability type
Exchange surface feature: permeability type
Selective permeability - only specific materials cross
Examples of specialised exchange surfaces
Examples of specialised exchange surfaces
Folded inner surface of lungs, branched structure of gills