IGCSE›Oxford AQA IGCSE Biology›Mind mapsContinuous and discontinuous variationOxford AQA IGCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsCausesDifferences between individuals of a speciesGenetic: different alleles from parentsEnvironmental: diet, temperature, sunlightMost traits are both, e.g. heightTwo typesContinuous: smooth range, e.g. heightContinuous: many genes, bell curveDiscontinuous: distinct categories, e.g. blood groupDiscontinuous: one or few genes, bar chartNatural selectionVariation exists in the populationSelection pressure: predators, disease, foodBest-suited individuals survive and breedAdvantageous alleles become more frequentVariationand evolutionEvidenceFossil record: change over timeAntibiotic resistance: rapid, observable evolutionHomologous bones suggest common ancestryDarwin (1859) lacked a mechanism; Mendel filled itMaking changesSelective breeding: slow, uses natural variationGenetic engineering: restriction enzyme cuts, ligase sealsCloning: identical copies, less diversitySpeciation: isolation → selection → no fertile offspringExam tipsContinuous is not the same as geneticName the factor: 'different alleles'Give natural selection steps in order