3.3.1 SA:V ratio

Cards (4)

  • SA:V- as organisms get bigger, their SA:V ratio decreases, meaning rate also decreases
  • Factors that affect the SA:V ratio:
    • Thickness of organism/ cell
    • Shape of organism/ cell
  • The surface area to volume ratio (SA:V) determines how fast substances diffuse into or out of cells.
  • Each unit of volume (V) of an organism requires a specific amount of surface area (SA) to supply it's metabolism with raw materials. The amount of SA available to each unit of V varies with the size of a cell. As a cell grows, it's SA:V ratio decreases- getting so small it can't supply the raw materials required for it's volume, meaning the cell can't get any larger.