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A female that is homozygous for an X-linked dominant trait is expected to pass on the trait to what proportion of her children?

A. All of her sons and half of her daughters
B. It depends on her husband's genotype.
C. Half of her sons and all of her daughters
D. All of her sons and all of her daughters.
E. Half of her sons and half of her daughters

1 Answer

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Final answer:

A female homozygous for an X-linked dominant trait will pass the dominant allele to all of her children, meaning all of her sons and all of her daughters will inherit and express the trait.

Step-by-step explanation:

When considering X-linked dominant traits, a female that is homozygous for the trait will transmit the allele to all her offspring regardless of sex. Since females have two X chromosomes, a homozygous female has the dominant allele on both of her X chromosomes. If we assume that alleles are inherited independently and follow Mendelian principles, then each child will inherit one of the mother's X chromosomes.

Therefore, all her sons will receive an X chromosome bearing the dominant allele (since they inherit their Y chromosome from their father and have no other X chromosome). Similarly, all her daughters will receive one X chromosome with the dominant allele, and, since the dominant trait will be expressed in the presence of a recessive allele on the other X chromosome (inherited from the father), all daughters will also express the trait. Thus, the correct answer is D: All of her sons and all of her daughters will inherit and express the X-linked dominant trait.

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