Question

a student traced a widow’s peak hairline in her family. based on her interviews and observations, she drew the following pedigree: which pattern(s) of inheritance are consistent with the pedigree? complete dominance sex - linked a and b only codominance

Explanation:

1. Complete Dominance Check: The trait (widow's peak) appears in every generation, affected individuals have at least one affected parent, and unaffected parents have only unaffected offspring. This matches autosomal dominant inheritance, a form of complete dominance.
2. Sex-Linked (X-linked Dominant) Check: X-linked dominant traits also appear in every generation, affected males pass the trait to all daughters (seen in the pedigree), and affected females can pass it to both sons and daughters (also seen). This pattern is consistent with the pedigree.
3. Codominance Check: Codominance would show both traits expressed simultaneously in heterozygotes, which is not indicated in the pedigree.

Answer:

A and B only