Question

A cross is made between true-breeding tall red-flowered plants and true-breeding short white-flowered plants. Tall and red are dominant traits. What would be the expected ratios of phenotypes in the F1 and F2 generations? What is the expected phenotypic ratio of the F2 generation if the red and white are codominant?

Answer 1

In a cross between true-breeding tall red-flowered plants and true-breeding short white-flowered plants, the F1 generation would result in all tall red-flowered plants. In the F2 generation, the expected phenotypic ratio would be 9 tall red-flowered plants : 3 tall white-flowered plants : 3 short red-flowered plants : 1 short white-flowered plant if the red and white traits are codominant.

Step-by-step explanation:

In a cross between true-breeding tall red-flowered plants (TTRR) and true-breeding short white-flowered plants (ttrr), the F1 generation would result in all tall red-flowered plants (TtRr). This is because the dominant traits for both height and flower color are passed on to the offspring.

In the F2 generation, the expected phenotypic ratio would be 9 tall red-flowered plants : 3 tall white-flowered plants : 3 short red-flowered plants : 1 short white-flowered plant. This is based on the 9:3:3:1 phenotypic ratio commonly observed in Mendelian inheritance.

If the red and white flower colors are codominant, the expected phenotypic ratio in the F2 generation would be 1 red : 2 pink : 1 white. In this case, both red and white traits would be expressed equally, resulting in pink flowers.