A Level Biology Revision (Year 13) "Dihybrid Inheritance"

In this A level Biology video, we look at dihybrid inheritance. First we look at how gametes are formed, in particular with two genes on different pairs of homologous chromosomes. We then look at how to carry out a dihybrid cross, looking at the inheritance of pea seed shape and colour (which was investigated by Gregor Mendel). We explore why the ratio of a dihybrid cross can be 9:3:3:1 in the offspring and why this shows that the genes are unlinked and obey Mendel's law of independent assortment. Image credits: Mendel pea traits https://commons.wikimedia.org/wiki/File:Mendel_pea_traits.svg Nefronus, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons