In a classical Mendelian cross between two individuals heterozygous for a single autosomal gene exhibiting complete dominance (Aa x Aa), what is the expected genotypic ratio among the offspring?
Answer and explanation
Correct answer: B. 1:2:1 (1 AA : 2 Aa : 1 aa)
A monohybrid cross between two heterozygotes (Aa x Aa) yields offspring with genotypes in the ratio 1 AA : 2 Aa : 1 aa (25% homozygous dominant, 50% heterozygous, 25% homozygous recessive). The 3:1 ratio is the phenotypic ratio under complete dominance, while 9:3:3:1 is the phenotypic ratio of an independent dihybrid cross.
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