BiologyGuideCells & MoleculesDiseasesEcosystemHuman BiologyAQA BIOL1AQA HBIO1AQA HBIO2AQA HBIO4AQA HBIO5
EcosystemFive KingdomsHuman ActivityInheritanceNutrient CyclePhotosynthesisSelectionVariation

Normal distribution about the mean

Causes of variation

Independent assortment of bivalents at the equator during anaphase I

Crossing over between non-sister chromatids during prophase I

Fertilization / random fusion of gametes

Gene mutation / increased by environmental factors (eg radiation)

Discontinuous variation

Continuous variation

Advantageous of variation to species