Practice question

If all progeny in a cross display dominant phenotype, no progeny could be homozygous recessive aa. A homozygous recessive parent always contributes a allele, so pairing with heterozygous Aa would generate 50% recessive offspring. Homozygous dominant parent AA contributes only A alleles, guaranteeing every zygote receives at least one dominant allele regardless of other parent genotype. Therefore uniform dominant progeny indicates presence of at least one AA parent among the pair. This outcome occurs in AA x AA, AA x Aa, and AA x aa crosses, consistent with complete dominance.