Two true-breeding stocks of pea plants are crossed. One parent has red, axial flowers and the other has white, terminal flowers; all F1 individuals have red, axial flowers. The genes for flower color and location assort independently. If 1000 F2 offspring resulted from a dihybrid cross, approximately how many of them would you expect to have red, terminal flowers?

Question

Quizplus · Accepted Answer

Given that the genes for flower color and location assort independently and considering the Mendelian inheritance, we can determine the expected phenotypic ratio for a dihybrid cross, which is 9:3:3:1. In this scenario, red is dominant over white, and axial is dominant over terminal. The question asks for red, terminal flowers, which falls under the 3/16 category (since red is dominant and terminal is the recessive trait being expressed). Therefore, out of 1000 F2 offspring, 3/16 would be expected to have red, terminal flowers. Calculating this gives 1000 * (3/16) = 187.5, which rounds to approximately 190.

Two True-Breeding Stocks of Pea Plants Are Crossed