Question

With independent assortment, the ratio of genotypes in the F2 generation of a cross between true-breeding strains (AA bb × aa BB) can be described as 1:2:1:2:4:2:1:2:1. To what genotype does the "4" in the ratio refer?

Answer 1

AaBb

Step-by-step explanation:

Cross between true breeding strains

Parents: AAbb x aaBB

Gametes: Ab aB

The F1 is homogeneous: AaBb.

To obtain the F2 generation we must do a cross between 2 F1 individuals: AaBb x AaBb

Their genotypes are the same, so they both will produce the same type of gametes: AB, Ab, aB and ab.

If you do a Punnett Square, you can check the ratio of genotypes of the F2, and that the "4" refers to AaBb.