Chapter 4, Problem 18PDQ

A geneticist from an alien planet that prohibits genetic research brought with him two true-breeding lines of frogs. One frog line croaks by uttering "rib-it rib-it" and has purple eyes. The other frog line croaks by muttering "knee-deep knee-deep" and has green eyes. He mated the two frog lines, producing F₁ frogs that were all utterers with blue eyes. A large F2 generation then yielded the following ratios:

27/64 blue, utterer

12/64 green, utterer

9/64 blue, mutterer

9/64 purple, utterer

4/64 green, mutterer

3/64 purple, mutterer

(a) How many total gene pairs are involved in the inheritance of both eye color and croaking?

(b) Of these, how many control eye color, and how many control croaking?

(c) Assign gene symbols for all phenotypes, and indicate the genotypes of the P₁, F₁, and F₂ frogs.

(d) After many years, the frog geneticist isolated true-breeding lines of all six F₂ phenotypes. Indicate the F₁ and F₂ phenotypic ratios of a cross between a blue, mutterer and a purple, utterer.