Human Heredity 11th Edition by Michael Cummings

Exercise 25

Two traits are examined simultaneously in a cross of two pure-breeding pea-plant varieties. Pod shape can be either swollen or pinched. Pea color can be either green or yellow. A plant with the traits swollen and green is crossed with a plant with the traits pinched and yellow, and a resulting F1 plant is self-crossed. A total of 640 F2 progeny are phenotypically categorized as follows: 360 swollen yellow
120 swollen green
120 pinched yellow
40 pinched green
A) What is the phenotypic ratio observed for pod shape? Pea color?
B) What is the phenotypic ratio observed for both traits considered together?
C) What is the dominance relationship for pod shape? Pea color?
D) Deduce the genotypes of the P1 and F1 generations.