In tomatoes,tall is dominant to short and smooth fruits are dominant to hairy fruits.A plant that is homozygous for both dominant traits is crossed with a plant that is homozygous for both recessive traits.The F₁ progeny are tested and crossed with the following results: 78 tall smooth fruits;82 short hairy fruits;22 tall hairy fruits;and 18 short smooth fruits.These data indicate that the genes are A) on different chromosomes. B) linked but do not cross over. C) linked and show 10 percent recombination. D) linked and show 20 percent recombination. E) linked and show 40 percent recombination.

Question

Quizplus · Accepted Answer

The data indicate that the two traits are linked, as the expected ratio of F2 offspring based on independent assortment would be 9:3:3:1 (tall smooth : tall hairy : short smooth : short hairy). The observed ratio of 78:22:18:82 indicates that the tall and smooth traits are linked together on one chromosome, while the short and hairy traits are linked together on the other chromosome. The recombination frequency between the two linked genes can be calculated as (22+18)/(78+22+18+82) = 0.2, or 20 percent. Therefore, choice D is the best answer.

In Tomatoes,tall Is Dominant to Short and Smooth Fruits Are