Solutions For An Introduction to Genetic Analysis Chapter 6 Problem 47P

b. To get the ratio of tryptophan-independent and tryptophan-dependent progeny in the cross of given wild types, cross the wild types as below:

Parent generation td; su (wild type) X td⁺; su⁺ (wild type)

F1 progeny will be as follows in the given proportions:

1td; su wild type

1 td; su⁺ requires tryptophan

1 td⁺; su⁺ wild type

1 td⁺; su wild type

We got the ratio of tryptophan dependent and tryptophan independent is 1:3.