The genotypes and phenotypes that result from the cross of Aa and Aa (A = normal pigmentation and a = albinism)are
A)phenotypes:75% normal and 25% albino; genotypes:25% homozygous dominant and 50% heterozygous and 25% homozygous recessive.
B)phenotypes:50% normal and 50% albino; genotypes:all homozygous recessive.
C)phenotypes:50% normal and 50% albino; genotypes:50% homozygous recessive and 50% homozygous dominant.
D)phenotypes:25% normal and 75% albino; genotypes:25% homozygous dominant and 50% heterozygous and 25% homozygous recessive.

Question

The genotypes and phenotypes that result from the cross of Aa and Aa (A = normal pigmentation and a = albinism)are
A)phenotypes:75% normal and 25% albino; genotypes:25% homozygous dominant and 50% heterozygous and 25% homozygous recessive.
B)phenotypes:50% normal and 50% albino; genotypes:all homozygous recessive.
C)phenotypes:50% normal and 50% albino; genotypes:50% homozygous recessive and 50% homozygous dominant.
D)phenotypes:25% normal and 75% albino; genotypes:25% homozygous dominant and 50% heterozygous and 25% homozygous recessive.

Quizplus · Accepted Answer

This is a classic example of a monohybrid cross. The Punnett square for this cross would show that 25% of the offspring would be homozygous dominant (AA) for normal pigmentation, 50% would be heterozygous (Aa) for normal pigmentation, and 25% would be homozygous recessive (aa) for albinism. Therefore, the phenotypic ratio would be 3:1 in favor of normal pigmentation (75% normal, 25% albino).

The Genotypes and Phenotypes That Result from the Cross of Aa