1. (4 pts) A cross was made between snapdragons with red and white flowers, and

Question

1. (4 pts) A cross was made between snapdragons with red and white flowers, and the resulting offspring were all pink. When the pink Fl snapdragons were crossed, the following offspring were produced: 125 red, 242 pink, and 121 white. A. Explain the inheritance of color in snapdragons. Give genotypes to all three phenotypes, using any logical nomenclature, B. Assume that one of the pink F, plants is crossed to a white plant. Of 400 offspring produced, what would be the expected numbers of red, pink, and white flowers? Explain your logic

Explanation / Answer

A. A snapdragon flower produces varities of colours due to the protein which encodes the colour of the flower which are controlled by genes.For the red types are the dominant and the white is the recessive one but when the red and white flowers are crossed and if the result is pink that is due to Incomplete dominance . Incomplete dominance is one where there is no complete dominance of the dominant gene and there is a expression of both the genes . That is , the red is not completely dominant over the recessive white gene leading to the blending of the colors.

If the genotype of dominant red types be RR

And the recessive white type be rr

Now when both are crossed then the F1 generation has Rr which leads to pink color that is incomplete dominance

RR + rr gives Rr and rR

B.If the F2 pink plant which has a genome of Rr is crossed with a white plant with genome rr then the result will only be the pink and white plants and no red plants will be produced due to the genome type because there is no way of producing RR gene.

If the pink F2 plant be of genotype Rr

And the white plant be rr

Then the result produced will be Rr and rr

And hence for 400 offsprings produced 200 will be of pink color and 200 will be of white color and no red flowers.

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