Mendel's phenotypic ratio in dihybrid cross is 9:3:3:1,what does it mean?

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Answer 1 · 2018-04-02T23:36:54

Dihybrid cross is a cross between two different lines/genes that differ in two observed traits.

Example: Dihybrid cross of two plants one with yellow round seed and another with green wrinkled seed.

$"Parent:" color(white)(.....) "YYRR" × "yyrr"$

$"F"_1: color(white)(....................) "YyRr"$

All the plants produced in $"F"_1$ generation are Yellow Round (Phenotypic character).

When $"F"_1$ progeny is self fertilised then progeny formed are shown below in Punnet square

Here you can see that phenotypic ratio is

$"9 Yellow Round" : "3 Yellow Wrinkled" : "3 Round Green" : "3 Green wrinkled"$

In a nutshell