Plant Reproduction
Mitchell and Emma are senior students that share a biology class. Their high school has a section on school property that has been used to grow various plants over the years. Each student is required to select a plant to study for their final project. The pictures show some of the plants that are grown on school property. The tulips, irises, and daffodils reproduce asexually. The snapdragons and the roses reproduce sexually.
Mitchell is interested in the snapdragons that reproduce sexually. He knows that purple (P) is dominant to white (w). Mitchell crosses a homozygous purple plant with a homozygous white plant. If he breeds two of the first generation offspring together, what percentage of the second generation offspring can Mitchell predict will most likely be white?
a
25%
b
50%
c
75%
d
100%
The answer is b) 50%.
When Mitchell crosses a homozygous purple plant (PP) with a homozygous white plant (ww), he will get all heterozygous purple offspring (Pw).
When he breeds two of the first generation offspring (Pw) together, he will get a 1:2:1 ratio of genotypes in the second generation offspring: PP, Pw, ww.
Therefore, there is a 25% chance of getting a homozygous purple plant, a 50% chance of getting a heterozygous purple plant, and a 25% chance of getting a homozygous white plant.