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3 votes
Given three possible phenotypes for parents showing dominance AA , Aa , aa which combination would produce a 1:2:1 ratio of genotypes and a 3:1 ratio of phenotypes

User LStarky
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2 Answers

6 votes
Aa and aa will give you a 1:2:1 ratio
Aa and Aa will give you a 3:1 ratio

a a

A Aa Aa

a aa aa

A a

A AA Aa

a Aa aa




5 votes

Answer:

A cross between two heterozygote individuals, Aa x Aa

Step-by-step explanation:

A cross between two heterozygotes individuals would produce a 1:2:1 ratio of genotypes and a 3:1 ratio of phenotypes. This is a case of complete dominance of one of the alleles over the other one. In this case, the allele A completely dominates over the allele a.

The cross would be like:

Parental) Aa x Aa

Gametes) A a A a

Punnet Square)

A a

A AA Aa

a Aa aa

The F1 genotype proportions are: 1/4 Homozygous dominant, AA

2/4 Heterozygous, Aa

1/4 Homozygous recessive, aa

The F1 phenotype proportions are: 3/4 of individuals expressing the

dominant trait.

1/4 of individuals expressing

the recessive trait.