Class 12th Biology 2016 Set1 Outside Delhi Board Paper Solution
Question 12
What is a test cross ? How can it decipher the heterozygosity of a plant ?
Answer
If the progenies produced by a test cross show 50% dominant trait and 50% recessive trait, then the cross in which the genotype of an unknown dominant phenotype can be determined by crossing it with an individual homozygous recessive phenotype for that trait is called test cross.
This cross determines whether the dominant character is coming from homozygous dominant genotype or heterozygous genotype, (eg. tallness coming from Tt) when Tt is cross with it, we obtain all Tt (tall) individuals in the program. Thus, test can be used to determine the heterozygosity of the plants.
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