Exchange surfaces

Question 1

Explain, in terms of surface area to volume ratio, why large multicellular organisms need specialised gas exchange systems and transport systems, whereas small single-celled organisms do not.

Answer 1

a larger size of an organism the smaller the sa to volume ratio
In smaller cellular organisms the sa to volume ratio is so large diffusion suficent enough to meet the demands of the cell
Large organisms cant supply themselves by relying on simple diffusion therefore transports systems help