Some dogs bark while trailing; others are silent. The barker gene is dominant, the silent gene reces

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Some dogs bark while trailing; others are silent. The barker gene is dominant, the silent gene recessive. These genes are not linked. The gene for normal tail is dominant over the gene for screw (curly) tail. A barker dog with a normal tail that is heterozygous for both traits is mated to another dog of the same genotype. What fraction of their offspring will be barkers with screw tails?

Accepted Answer

Sol.(c) [Key Concept: Dihybrid Cross — Phenotypic Fractions] Cross: BbNn × BbNn (where B=barker, N=normal tail). Expected ratios: 9 B_N_ (barker, normal tail) : 3 B_nn (barker, screw tail) : 3 bbN_ (silent, normal tail) : 1 bbnn (silent, screw tail). Barkers with screw tails (B_nn) = 3/16. This is the standard dihybrid cross giving 9:3:3:1 ratio.

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