Question

based on the pedigree that is shown, which describes john?

carrier for hemophilia
expresses hemophilia
does not have hemophilia
expresses hemophilia and died of complications

Explanation:

Identify the individual in question

The question asks which option describes John. Looking at the pedigree, the child of Charles (\(X^H Y\)) and Marie (\(X^H X^h\)) is represented by a shaded square with a question mark underneath. This male child is John.

Determine John's genotype

John is a male, so he inherits a \(Y\) chromosome from his father, Charles, and one of the \(X\) chromosomes from his mother, Marie.
Marie is a carrier with the genotype \(X^H X^h\).
The pedigree shows John's square is fully shaded, indicating that he is affected by the condition (hemophilia). Therefore, he must have inherited the recessive disease-causing allele \(X^h\) from his mother.
His genotype is \(X^h Y\).

Analyze John's phenotype

Since hemophilia is an X-linked recessive disorder, a male with the genotype \(X^h Y\) has only one copy of the X chromosome and will fully express the trait.
Thus, John expresses hemophilia.

Answer:

Based on the pedigree that is shown, which describes John?

• carrier for hemophilia
• expresses hemophilia (Correct answer)
• does not have hemophilia
• expresses hemophilia and died of complications