You have a pair of breeding guinea pigs You keep track of th

You have a pair of breeding guinea pigs. You keep track of their litters until you have data on 350 baby guinea pigs. 70 of the babies had pointy ears and brown eyes. 190 of the babies had rounded ears and brown eyes. 25 of the babies had pointy ears and green eyes. Finally, 65 of the babies had rounded ears and green eyes.

1. What are the genotypes of your two breeding guinea pigs?

2. What is the phenotypic ratio seen in the offspring?

3. What traits are dominant traits? What traits are recessive?

Solution

Answer:

Dihybrid cross ratio is 9:3:3:1

190 : 70 : 65 : 25 = 9:3:3:1

Rounded ears and brown eyes = 190 (P_E_)

Pointy ears and brown eyes= 70(ppE_)

Rounded ears and green eyes= 65 ( P_ee)

Pointy ears and green eyes = 25 (ppee)

1) PpEe x PpEe

2) 9:3:3:1

3).

Round ears & Brown eyes are dominant traits

Pointy ears & green eyes are recessive traits.

Round ears are dominant over pointy ears.

Brown eyes are dominant over green eyes