GCSE›AQA GCSE Biology›Mind mapsPrinciples of OrganisationAQA GCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsThe hierarchyCells are the basic building blocksTissues: similar cells doing the same jobOrgans: different tissues working togetherOrgan systems: organs working for the whole organismDigestive systemAn organ system for digesting and absorbing foodIncludes stomach, small intestine, liver and pancreasEach organ has different tissuesAll contribute to one overall functionEnzymesBiological catalysts made of proteinShape of the active site makes them specificLock and key: only a complementary substrate fitsOrganisationcells to organ systemsEnzyme activityRate rises with temperature up to an optimumThen falls sharply as the enzyme denaturesDenatured: active site shape destroyedEach enzyme has an optimum pHCirculatory systemThe heart is an organ made of muscle tissueRight side pumps blood to the lungsLeft side pumps blood round the bodyExam tipsDigestive system: several organs, one overall functionExplain lock and key using substrate and active siteName the specific organ, not just the system