Question

in the family tree below, people with the recessive trait of attached ear are shaded gray. what must be true about the person labeled \a\? a. it is a male with at least one dominant allele. b. it is a female with two dominant alleles. c. it is a female with at least one dominant allele. d. it is a male with two dominant alleles.

Explanation:

Step1: Analyze family - tree symbols

In a family - tree, squares represent males and circles represent females. The square labeled 'A' is a male.

Step2: Analyze trait inheritance

Since the shaded - gray represents the recessive trait and 'A' is not shaded, 'A' has at least one dominant allele (because having at least one dominant allele masks the recessive trait). We cannot be sure if 'A' has two dominant alleles or one dominant and one recessive allele.

Answer:

A. It is a male with at least one dominant allele