Question

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In rats, the pigment gene has two alleles: the P allele is dominant and confers no pigment in the hair (no color); the p allele is recessive and confers hair pigment (color). A second gene, black, also has two alleles: the B allele is dominant and confers black hair pigment and the b allele is recessive and confers tan hair pigment. The dominant P allele is epistatic on both alleles of the black gene. A pure-breeding black-haired rat is crossed to a rat that has the genotype PP bb. Their progeny are the F1. These F1 rats are then crossed to each other. What would be the expected proportion of the F2 progeny that would be unpigmented? __________________________

Answer 1