Dihybrid Cross

For homework tonight, we are learning about dihybrid crosses, which involve two traits. I have made an example question below.



In this example, the a homozygous dominant father (TTZZ) and a homozygous recessive mother (ttzz) breed and have offspring. All of the offspring, F1 generation, are heterozygous (TtZz). Having a tan (T) is the dominant trait and not having a tan (t) is the recessive trait. Also, having a zigzag tattoo (Z) is the dominant and having no zigzag tattoo (z) is recessive.

The genotype ratio is 1 TTZZ: 2 TTZz : 2 TtZZ : 1 TTzz: 4 TtZz : 1 ttZZ: 2 Ttzz : 2 ttZz : 1 ttzz, and the phenotype ration is 9 tan/zigzag tattoo: 3 tan/no tattoo: 3 no tan/zigzag tattoo: 1 no tan/no tattoo.

Below is a cool example of another dihybrid cross. Four different cats are produced, with the color and the length of tail changing.