57.3k views
1 vote
If there is complete dominance, what will be the phenotypic ratio for the offspring of a AaGG x Aagg cross?

A. 3:1
B. 1:1:1:1
C. 9:3:3:1
D. 1:2:1
E. 1:1

User Ze Blob
by
8.3k points

1 Answer

6 votes

Answer + Explanation

If there is complete dominance, the phenotypic ratio for the offspring of a AaGG x Aagg cross will be 1:1:1:1, which corresponds to option B.

In this cross, the A allele is dominant over the a allele, and the G allele is dominant over the g allele.

The genotypes of the parent organisms are:

- AaGG: heterozygous for allele A and homozygous dominant for allele G

- Aagg: heterozygous for allele A and homozygous recessive for allele G

When these two organisms are crossed, the possible genotypes of the offspring are:

- AaGG: 1/4 chance

- AaGg: 1/4 chance

- AaGG: 1/4 chance

- Aagg: 1/4 chance

Since each genotype has an equal probability of occurring, the phenotypic ratio will also be equal, resulting in a 1:1:1:1 phenotypic ratio

hope this helps!

User Abhijith Sasikumar
by
7.8k points