exchanging substances

organisms exchange substances with their environement 

1) cells can use diffusion to take in substances they need and get rid of waste products. 

2) how easy it is or an organism to exchange substances with its environment depends on the organisms surface area to volume ratio. 

multicellular organisms need exchange surfaces 

in single celled organisms gases and dissolved substances can diffuse directly into or out of the cell because they have a large surface area compared to their volume so enough substances can be exchanged…