# GCSE biology help

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#1
hi can someone help me with this q 5.5. plsss
Last edited by mohona1827; 1 month ago
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1 month ago
#2
The genotype is Dd this is because they produce one daughter who doesn’t have the disorder and that wouldn’t be possible if the genotype was DD due to the disorder being a dominant trait.

Punnet square: we know the parent genotype are the same as parent 1 and 2 due to their ability to produce a daughter who is totally unaffected and therefore dd

D d
d Dd dd
d Dd dd
So both children in the left hand column would have the disorder and therefore thats 2/4 or the probability is 50:50.

The diagram shows it’s not on the Y chromosome because 3,11 and 12 are all female yet have the disorder. Females do not have a Y chromosome so therefore the allele cannot physically be carried on the Y chromosome (otherwise it would be impossible for females to have it) and must be carried on a different one.

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#3
(Original post by Wannabevet133)
The genotype is Dd this is because they produce one daughter who doesn’t have the disorder and that wouldn’t be possible if the genotype was DD due to the disorder being a dominant trait.

Punnet square: we know the parent genotype are the same as parent 1 and 2 due to their ability to produce a daughter who is totally unaffected and therefore dd

D d
d Dd dd
d Dd dd
So both children in the left hand column would have the disorder and therefore thats 2/4 or the probability is 50:50.

The diagram shows it’s not on the Y chromosome because 3,11 and 12 are all female yet have the disorder. Females do not have a Y chromosome so therefore the allele cannot physically be carried on the Y chromosome (otherwise it would be impossible for females to have it) and must be carried on a different one.

hey thank you for helping me out yes i understand it much better now
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