Refer to the diagram below showing a pedigree of a sex-linked recessive trait. In generation II, female number 5 marries a man and has three children. One daughter and one son do not have the recessive trait; the other son does have the recessive trait. Based on these results, one can conclude that

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Quizplus · Accepted Answer

Since one of the sons does not have the trait, we know that the father cannot be homozygous recessive (since all of his sons would then have the trait). Therefore, the mother must be a carrier (heterozygous) for the trait and passed on the dominant allele to the unaffected daughter and one son, while passing on the recessive allele to the affected son.

Refer to the Diagram Below Showing a Pedigree of a Sex-Linked