1. Test Cross

2. Test Cross
Used for organisms with an unknown genotype (but known dominant phenotype)
determines if their dominant phenotype is due to a heterozygous or homozygous genotype
What type of genotype should the organism be crossed with to determine this? g
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3. Sample Problem 1: The Test Cross
1. In dogs, there is an hereditary deafness caused by a recessive gene,“d.” A kennel owner has a male dog that she wants to use for breeding purposes. The dog can hear, so the owner knows his genotype is either DD or Dd. If the dog’s genotype is Dd, the owner does not wish to use him for breeding so that the deafness gene will not be passed on.
What cross should the breeder perform to determine the dog's genotype? Explain how she can use the results to determine the genotype of the male dog.