AQA A-LEVEL BIOLOGY TOPIC 3 UPGRADED EXAM QUESTIONS AND ANSWERS

AQA A-LEVEL BIOLOGY TOPIC 3 UPGRADED EXAM QUESTIONS AND ANSWERS Why are Microorganisms able to perform exchange via their surface? - CORRECT ANSWER -• have a large surface area to volume ratio • have a short diffusion distance • have low demand How do Microorganisms Obtain Nutrients & Remove Waste? - CORRECT ANSWER -• 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? - CORRECT ANSWER -• 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 Why do Fish have Specialised Gas Exchange Systems? - CORRECT ANSWER -• multicellular organism so has a small surface area to volume ratio, large diffusion distance, high demand & body surface impermeable • therefore, cannot perform gas exchange (O2 in/CO2 out) via their surface, they require a specialised gas exchange system called Gills