In a certain species of plant, flowers occur in three colors: blue, pink, and white.A pure-breeding pink plant is mated with a pure-breeding white plant.All of the F₁ are blue.When the blue F₁ plants are selfed, the F₂ occur in the ratio 9 blue:3 pink:4 white.The genotype that produces white is ww.The presence of one W allele allows pink or blue color to occur.The alleles at the hypostatic locus are B (blue)and b (pink).What is the genotype of the F₁ plants?

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First, we know that the pink plant is pure-breeding which means it must be homozygous for the recessive allele of the B/b gene, bb. The white plant is also pure-breeding, meaning it must be homozygous for the ww genotype. When these plants are crossed, we know that the F1 generation will be heterozygous for both genes (Bb Ww). Next, we look at the selfed F2 generation. We see that 9/16 of the plants are blue, 3/16 are pink, and 4/16 are white. This ratio matches that of a dihybrid cross involving two heterozygous individuals, which is what we have in the F1 generation. From the ratio, we know that the blue plants must be homozygous dominant for both genes (BB WW), as they only produce blue offspring when selfed. To determine the genotype of the F1 generation, we can set up a Punnett square using the genotypes of the pink and white parents. We would get the following: | | W | w | |---|---|---| | B | BW | Bw | | b | bw | bw | The F1 generation would all be Bb Ww. Therefore, the genotype of the F₁ plants must be Bb Ww.

In a Certain Species of Plant, Flowers Occur in Three