3.3.1 Surface area to volume ratio

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sabawoon

Cards (8)

  • As size increases, SA:V tends to decrease
  • More thin / flat / folded / elongated structures increase SA:V
  • How to calculate SA:V
    Divide surface area (size length x side width x number of sides) by volume (length x width x depth)
  • SA:mass
    Easier / quicker to find / more accurate because irregular shapes
  • Metabolic rate
    Amount of energy used up by an organism within a given period of time
  • Metabolic rate is often measured by oxygen uptake as used in aerobic respiration to make ATP for energy release
  • As SA:V increases (smaller organisms)

    Metabolic rate increases
  • Adaptations that facilitate exchange as SA:V reduces in larger organisms
    • Changes to body shape (eg. long / thin) to increase SA:V and overcome long diffusion distance / pathway
    • Development of systems, such as a specialised surface / organ for gaseous exchange e.g. lungs, to increase (internal) SA:V and overcome long diffusion distance / pathway, and maintain a concentration gradient for diffusion