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Home Q & A Board Science-Related Homework Help High School Level Science
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Aliya1 Aliya1
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6 years ago
#19. Hemophilia is a sex-linked recessive trait. A male hemophiliac and phenotypically normal female have a daughter that is a hemophiliac.

Create a Punnett square that depicts the described parental cross. (1 mark)
Explain why it is far more common for a male to be a hemophiliac than a female. (1 mark)
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Educator
6 years ago Edited: 6 years ago, bio_man
Good morning Aliya1

Quote from: Aliya1 (6 years ago)
#19. Hemophilia is a sex-linked recessive trait. A male hemophiliac and phenotypically normal female have a daughter that is a hemophiliac.

Create a Punnett square that depicts the described parental cross. (1 mark)
Explain why it is far more common for a male to be a hemophiliac than a female. (1 mark)

Male hemophiliac would be XNY
Female would have to be: XNXn

         XN         Y
XN   XNXN   XNY
Xn   XNXn   XnY

Because females have two x chromosomes, one good gene will compensate for the bad gene. Whereas males, whose sex genotype consists of 1 X, they only get one chance. If they inherit a bad gene, they have it, and don't have an opporunity to escape as do females.

Notice that the girl has a 50% chance of being affected!
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Aliya1 AuthorAliya1
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Posts: 351
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6 years ago
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