What is the Mendelian ratio?

1 Answer
Dec 18, 2015

For a monohybrid cross, the phenotypic ratio is #3:1#. This occurs because when #"Aa"# #xx# #"Aa"#, the result is #1# #"AA"#, #2# #"Aa"#, and #1# #"aa"#.

The #"AA"# and #2# #"Aa"# represent the dominant phenotype since they contain the dominant allele #"A"#.

There is only #1# cross that results in a recessive phenotype: #"aa"#.

Since there are three dominant phenotypes to one recessive, the common ratio is #3:1#.

http://images.tutorvista.com/content/heredity-and-variation/mendels-monohybrid-inheritance.jpeg

There is also a common ratio for a dihybrid cross: #9:3:3:1#.

http://www.biologycorner.com