In sweet peas, purple flower color and oblong pollen grains are dominant, with the recessives being red flower color and spherical pollen grains. When a homozygous purple, oblong plant is crossed with a homozygous red, spherical plant, the F₁ generation consists entirely of purple, oblong plants. When an F₁ plant is crossed with a homozygous red, spherical plant, the offspring are produced in a ratio of 7 purple, oblong to 1 purple, spherical to 1 red, oblong to 7 red, spherical. Which of the following is the only plausible explanation for such results?

Question

Quizplus · Accepted Answer

The observed offspring ratio deviates significantly from the expected 9:3:3:1 Mendelian ratio for a dihybrid cross, suggesting that the genes for flower color and pollen shape are linked on the same chromosome, hence not assorting independently. This linkage alters the expected phenotypic ratios, leading to the specific 7:1:1:7 ratio observed.

In Sweet Peas, Purple Flower Color and Oblong Pollen Grains