[Campbell Biology P.323] What is the purpose of a testcross? | Practice Question

What is the purpose of a testcross?

  • A: To produce a new true-breeding variety.
  • B: To determine the genotype of an organism with a dominant phenotype.
  • C: To create a hybrid organism with two different traits.
  • D: To observe the 3:1 phenotypic ratio in the offspring.

Explanation

The text defines a testcross as 'Breeding an organism of unknown genotype with a recessive homozygote... because it can reveal the genotype of that organism.' It is used when an organism displays a dominant phenotype and could be either homozygous dominant PP or heterozygous Pp .