Two parents, one hemophilic and the other carrier female, chances among the male offspring to be hemophilic:
Correct answer: B. 50%
- A. 25%
- B. 50%
- C. 75%
- D. 100%
Explanation
In the extremely rare event that both the mother and father have the affected X chromosomes, there is a 50% chance that their sons will be born with hemophilia. There will be a 50% chance that their daughters will be carriers and a 50% chance of them being hemophilic.50%The hemophilic parent is presumably the father, since hemophilia is an X-linked recessive trait. The carrier female parent has one normal X chromosome and one X chromosome with the hemophilia gene.The male offspring have a 50% chance of inheriting the X chromosome with the hemophilia gene, making them hemophilic. The other 50% of the time, they will inherit the normal X chromosome and be unaffected.The female offspring have a 50% chance of being carriers like their mother, and a 50% chance of being unaffected.
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About Inheritance
Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.
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