3.In some breeds of dogs a dominant allele controls the characteristic of barking while trailing.

HI there

Excellent question.


       B  = barker      E = erect ears
        b   = silent               e  = drooping ears

                   wanted: BBee
                   but all genotypes present in kennel

          1.  eliminate all dogs with erect eaers (EE and Ee)
          2.  of remaining dogs (BBee and Bbee) & bbee
          3.  breed the silent, drooping-eared dogs to all barking droop-eared dogs
          → any litters containing silent dogs come from heterozygous (Bb) parents
          → eliminate these pups and their parents
           The remaining stock should be only BBee
           (this illustrates a test-cross)

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