Question

explin why organism when they are bigger than 1mm need to have other ways apart from diffusion of exchanging materials with their surroundings

Answer 1

The appropriate answer is

So as organisms get bigger their surface area/volume ratio gets smaller. A bacterium is all surface with not much inside, while a whale is all insides with not much surface. This means that as organisms become bigger it becomes more difficult for them to exchange materials with their surroundings.18 Jun 2004