Question

A test cross is done to find out

• A. The genotype of an individual by examining the phenotypes of its offsprings from a particular mating
• B. The genotype of an individual for testing for its DNA content
• C. Whether a mating is fertile
• D. Whether two species can interbreed

Answer 1

The correct option is A The genotype of an individual by examining the phenotypes of its offsprings from a particular mating

A test cross is the cross of any individual to a homozygous recessive parent.

It may be used to establish the genotype of an individual with the dominant phenotype.

e.g: Genotype could be AA or Aa so crossing with aa will give us different results.

AA x aa = All Aa (All one phenotype)

Aa x aa = 1 Aa: 1 aa (half one phenotype, half other)

The appearance of the recessive phenotype in the offspring of a test cross indicates that the unknown genotype was heterozygous.

A test cross can also occur with 2 or more genes involved.