10.2  Inheritance

big ninja

Essential Idea:

Genes may be linked or unlinked  

and are inherited accordingly


  • Gene loci are said to be linked if on the same chromosome
  • Unlinked genes segregate independently as a result of meiosis
  • Variation can be discrete or continuous
  • The phenotypes of polygenic characteristics tend to show continuous variation
  • Chi-squared tests are used to determine whether the difference between an observed and expected frequency distribution is statistically significant


  • Morgan’s discovery of non-Mendelian ratios in Drosophila
  • Completion and analysis of Punnett squares for dihybrid traits
  • Polygenic traits such as human height may also be influenced by environmental factors


  • Calculation of the predicted genotypic and phenotypic ratio of offspring of dihybrid crosses involving unlinked autosomal genes
  • Identification of recombinants in crosses involving two linked genes
  • Use of a chi-squared test on data from dihybrid crosses