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

Question

Quizplus · Accepted Answer

The cross between Aa (heterozygous) and aa (homozygous recessive) results in a 50% chance of normal pigmentation (Aa) and a 50% chance of albinism (aa) in the offspring. The genotypes of the offspring are 50% heterozygous (Aa) and 50% homozygous recessive (aa). Therefore, the correct answer is C. Option A is incorrect because it suggests all offspring will be normal, which is not the case. Option B is incorrect because it suggests all offspring will be albino, but some will be heterozygous. Option D is incorrect because it suggests all offspring will be albino, but some will be heterozygous for the dominant allele.

The Phenotypes and Genotypes That Result from a Cross of Aa