A-level Biology Notes

Why can't animal/plants preform exchange via their surface?

-Have a small surface area to volume ratio

-Multi cellular [large diffusion distance on high demand]

-Impermeable surface [prevents pathogens entering and reduces water loss]

-Therefore comment require specialized exchange and transport systems

-Exchange system = increases rate of diffusion of nutrients in and waste out 

-transport system= deliver nutrients and remove waste from all cells