Variation in phenotype


Continuous data:

  • Intermediate forms - eg height
  • Can be represented by a distribution curve
  • Continous variation

Image result for distribution curve

Discontinuous data:

  • Does not show intermediate forms - categories eg blood type
  • Can be represented as a bar chart
  • Discontinuous variation
  • Environmental factors have little influence on this

Image result for bar chart

Genetic causes of variation:

Mutations -

  • sudden changes to genes and chromosomes may, or may not be passed onto the next generation
  • mutations are a main source of variation

Meiosis -

  • homologous chromosomes split into daughter cells
  • independent assortment of these chromosomes
  • produces new combinations of alleles

Random fertilisation of gametes -

  • sexual reproduction produces


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