BIO genetics question

[d wannabe]

Hi,
Can someone help me with this question?

Q: If a male hemophiliac (X^h Y) is crossed with a female carrier of both color blindness and hemophilia (X^c X^h), what is the probability that a female child will be phenotypically normal?

1) 0%
2) 25%
3) 50%
4) Same as for a male child

The answer is 3) 50%.
I thought it is 0%
-> one female child: (X^c X^h) : Both hemophiliac and color blindness
one female child: (X^h X^h) : Hemophiliac

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[nt4reall]

Hi,
Can someone help me with this question?

Q: If a male hemophiliac (X^h Y) is crossed with a female carrier of both color blindness and hemophilia (X^c X^h), what is the probability that a female child will be phenotypically normal?

1) 0%
2) 25%
3) 50%
4) Same as for a male child

The answer is 3) 50%.
I thought it is 0%
-> one female child: (X^c X^h) : Both hemophiliac and color blindness
one female child: (X^h X^h) : Hemophiliac

I think the answer is correct because it asked about phenotype not genenotype , 50% of female will be hemophilliac . Hemophilliac is a sickle anemia disease or some disease which related to red blood cell . Therefore , female which this disease still has normal phenotype . For the color blindness female , she can not see the color , therefore, it shows abnormal phenotype . I don't know whether it's correct or not . Somebody helps???

 

[mddang]

Hemophilia and color blindness are recessive disorders.

For a female to have either one of these disorders, both X chromosomes (homozygous) must carry the defected gene.


The father will always pass down his X^h to his daughter.

The mother can pass down either one of the X chromosomes to the daughter. If the X^h is passed to the daughter, the daughter will have hemophilia.

If the X^c is passed to the daughter, the daughter will be heterozygous for the color blindness gene and for the hemophilia gene. The daughter would be normal in this case.

The mother carries 2 different X chromosomes, and each chromosome has a 50% chance of being passed on.

 

[nt4reall]

Hemophilia and color blindness are recessive disorders.

For a female to have either one of these disorders, both X chromosomes (homozygous) must carry the defected gene.


The father will always pass down his X^h to his daughter.

The mother can pass down either one of the X chromosomes to the daughter. If the X^h is passed to the daughter, the daughter will have hemophilia.

If the X^c is passed to the daughter, the daughter will be heterozygous for the color blindness gene and for the hemophilia gene. The daughter would be normal in this case.

The mother carries 2 different X chromosomes, and each chromosome has a 50% chance of being passed on.

okie , i understand the problem now . X^cX^h is normal because this female is a carrier of color blindness and carrier of hemophilia.

 

[americanpierg]

lol wow i picked 0 right off the bat too. I better start reading more closely