The process which removes/eliminates excretory wastes to the outside of the organism.

This is necessary, because:

  • accumulation of metabolic waste would slow down and evenutally stop chemical reactions which makes up an organism's metabolism and to maintain its equilibrium.
  • excretory waste are toxic, interfering with key metabolic steps.
  • diluting effect of the excessive accumulation of water within a cell also slows down metabolic reactions.
      e.g. swelling of cells.