Question

Which following statement(s) is(are) true about progeny testing for simply-inherited traits? (Circle all the correct answers)

A. Test crosses are performed to determine whether a deleterious allele is dominant.

B. You need to produce more offspring to reach 95% probability of detection if you mate a carrier with a known carrier than with its daughter.

C. Detection with 20 progeny and no detection with 20 progeny from two crosses of the same parents are independent events.

D. You always need to perform a test cross when only additive gene action exists in a locus. E. You always need to perform a test cross when dominant gene action exists in a locus.

Answer 1

The test cross is carried out so that we can know the genotype of the offspring and also we can know whether the a deleterious allele is following a recessive or dominant pattern of inheritance. The detection of 20 progeny and no detection with 20 progeny from two crosses of same parents are independent events as 2 crosses have random gametes fusion and random progeny formation. More progeny are required to detect the trait of the offspring being inherited.

Hence all the options given in the question are true about progeny testing for simply-inherited traits.

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