Question

if the dominant allele is represented by a and the recessive allele is represented by a, what would be a possible genotype and phenotype of individual ii.3?
a. genotype: aa
phenotype: carrier
b. genotype: aa
phenotype: affected
c. genotype: aa
phenotype: unaffected
d. genotype: aa
phenotype: unaffected

Explanation:

1. Analyze Option A: A carrier typically has a heterozygous genotype (Aa) for a recessive trait. AA is homozygous dominant, so the phenotype should be unaffected, not a carrier. Eliminate A.
2. Analyze Option B: For a recessive disorder, the affected phenotype is usually associated with aa (homozygous recessive). Aa is a carrier (or unaffected if dominant allele is expressed), not affected. Eliminate B.
3. Analyze Option C: AA is homozygous dominant. Since the dominant allele (A) is present, the individual will show the dominant (unaffected) phenotype. This is consistent.
4. Analyze Option D: aa is homozygous recessive. For most recessive traits, aa would result in the affected phenotype, not unaffected. Eliminate D.

Answer:

C. Genotype: AA; Phenotype: unaffected