Question

why can't diffusion work in multicellular organisims

Answer 1

When the surface area to volume ratio is small, then there is not much surface area for substances to diffuse across but there are lots of cells inside that need the substances (a high volume). The multicellular organism can't rely just on diffusion to get the substances that all of its cells need.

Explanation:

Here is your answer.

Answer 2

Answer:

When the surface area to volume ratio is small, then there is not much surface area for substances to diffuse across but there are lots of cells inside that need the substances (a high volume). The multicellular organism can't rely just on diffusion to get the substances that all of its cells need.