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A brown eyed couple has a blue- eyed chi...

A brown eyed couple has a blue- eyed child . The trait of brown eye (B) is dominant over blue-eye (b). What is the genotype of the couple ?

A

Bb `xx`Bb

B

`BB xxBB`

C

`BBxxBb`

D

`BBxxbb`

Text Solution

AI Generated Solution

The correct Answer is:
To determine the genotype of the brown-eyed couple who has a blue-eyed child, we can follow these steps: ### Step 1: Understand the Traits - Brown eyes (B) are dominant over blue eyes (b). - This means that a person with at least one dominant allele (B) will have brown eyes, while a person with two recessive alleles (bb) will have blue eyes. ### Step 2: Analyze the Child's Genotype - The child has blue eyes, which indicates that the child must have the genotype (bb). This is because blue eyes are only expressed when both alleles are recessive. ### Step 3: Determine the Possible Genotypes of the Parents - Since both parents are brown-eyed, their genotypes could either be homozygous dominant (BB) or heterozygous (Bb). - However, if both parents were homozygous dominant (BB), they could only produce offspring with brown eyes (BB or Bb), and would not be able to produce a blue-eyed child (bb). ### Step 4: Conclusion about the Parents' Genotype - Therefore, both parents must be heterozygous (Bb) in order to have a child with the blue-eyed genotype (bb). - The possible combinations from two Bb parents would be: - BB (brown eyes) - Bb (brown eyes) - Bb (brown eyes) - bb (blue eyes) ### Final Answer - The genotype of the brown-eyed couple is Bb (heterozygous).
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