bio

• surface area

  • total area over which substances and heat can be exchanged
• volume

  • total internal space
  • as volume increases more materials needed as there are more cells so metabolism increases
• SA:V ratio

  • increase in organism size leads to increase in volume as their are more cells.
  • increase in number of cells means there is less surface area for exchange of materials as many cells in contact with another.
  • ratio decreases with increasing organism size
• adaptations to sa:v ratio

  • large surface area allows more of substance to diffuse at same time
  • thin membrane reduces diffusion distence
  • transport systems move substances around organism/facilitate exchange. allows higher concentration gradient to me maintained.