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A women with blue eyes, a recessive trait, marries a man with brown eyes, the dominant trait. They have children with both blue eyes and brown eyes. Question:

What are the genotypes of the parents?
Complete the genetic cross and describe the ratio of blue to brown eyes among the children.
What are the genotypes of the children?
and list what letter is for what please

User Jzeef
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1 Answer

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Blue eye colour is a recessive trait and thus we will represent it by “b”

Brown eye colour is a dominant trait and thus we will represent it by “B”

Mother is blue eyed thus its genotype would be “bb”

Father is brown eyed thus its genotype would be either “BB” or “Bb”, but here is this question the offspring’s are both brown and blue eyed and thus, father genotype in this case would be “Bb”

a) What are the genotypes of the parents?

Mother Genotype – bb

Father Genotype – Bb

b) Complete the genetic cross and describe the ratio of blue to brown eyes among the children.

Genetic Cross

Bb X bb

Bb, Bb, bb, bb

Brown eyed children – 2 in numbers “Bb”

Blue eyed children – 2 in numbers “bb”

Ratio of blue to brown eyes among the children: 2:2

c) What are the genotypes of the children?

Brown eyed children – “Bb”

Blue eyed children – “bb”

d) list what letter is for what please

b = blue colour

B = brown color

X = cross between two genotypes

User Bince
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