GCSE›Edexcel GCSE Biology›Mind mapsTransport in AnimalsEdexcel GCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsWhy transport?Carries oxygen and carbon dioxideCarries water, dissolved food, ionsCarries urea to be excretedSurface areaBigger organisms have smaller SA:volume ratioDiffusion alone becomes too slowNeed exchange surfaces and a transport system2 cm cube: ratio 3:1, 4 cm cube: 1.5:1BloodRed cells carry oxygen via haemoglobinRed cells: no nucleus, biconcavePhagocytes engulf pathogensLymphocytes produce antibodiesPlasma carries dissolved substances and heatPlatelets clot bloodAnimal transportblood and vesselsArteriesThick, muscular wall, narrow lumenHigh pressure, away from heartVeins and capillariesVeins: thin wall, wide lumen, valvesVeins: low pressure, to heartCapillaries: one cell thick, exchange with tissuesExam tipsPhagocytes engulf, lymphocytes make antibodiesValves belong to veins, not arteriesSay SA:volume ratio decreases as size increases