AQA A-Level Biology Topic 3 Already Passed 2024

Why are Microorganisms able to perform exchange via their surface? • have a large surface area to volume ratio • have a short diffusion distance • have low demand How do Microorganisms Obtain Nutrients & Remove Waste? • by exchange via their surface • nutrients (e.g. glucose, oxygen) move in by diffusion via their surface • waste (e.g. carbon dioxide) move out by diffusion via their surface Why can't Animals/Plants perform exchange via their surface? • have a small surface area to volume ratio • multicellular (large diffusion distance and high demand) • impermeable surface (prevent pathogens entering and reduce water loss) • therefore, require specialised Exchange & Transport systems • exchange system = increases rate of diffusion of nutrients in and wastes out • transport system = deliver nutrients and remove waste from all cells