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Brown eyes are dominant over blue eyes. In addition, colour blindness(n) is sex-...

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islnds | Valedictorian

Posted April 15, 2013 at 2:20 PM via web

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Brown eyes are dominant over blue eyes. In addition, colour blindness(n) is sex- linked. What type of offspring would be produced from the following cross?

BbXNXN      and      BbXnY

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jerichorayel | College Teacher | (Level 1) Senior Educator

Posted April 15, 2013 at 4:47 PM (Answer #1)

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Both of the parents are heterozygous brown eyes (Bb). Doing the punnet square the results would be:

         B      b

B      BB    Bb

b      Bb    bb

 

50% Heterozygous brown eyes

25% Homozygous brown eyes

25% blue eyes (recessive trait)

 

For the x-linked trait color blindness, the resulting offspring would be:

Parents:

Male: `X^nY` -> color blind male

Female: `X^NX^N` -> Normal female

     

                 `X^n`          `Y`

`X^N`    `X^NX^n`   `X^NY`

`X^N`    `X^NX^n`   `X^NY`

 

Results: 

50% Carrier female

50% Normal male

Sources:

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