Gas Exchange RG

• What TWO MAJOR ADAPTIONS do gas exchange surfaces have- which INCREASE rate of diffusion ?

  • Large surface area
  • thin (often ONLY 1 layer of epithelial cells) which provides a short diffusion pathway across the gas exchange surface
  • The organism also MAINTAINS A STEEP CONCENTRATION GRADIENT OF GASES ACROSS the exchange surface
• how do single-celled organisms absorb and release gases?

  by diffusion through their outer surface
• why is there no need for single-celled organisms to have a gas exchange system?

  • relatively large surface area
  • Thin surface
  • short diffusion pathway (oxygen can take part in biochemical reactions as soon as it diffuses into the cell )