Two pure-breeding wheat strains, one producing dark red kernels a...

Question

Two pure-breeding wheat strains, one producing dark red kernels and the other producing white kernels, are crossed to produce F₁ with pink kernel color. When an F₁ plant is self-fertilized and its seed collected and planted, the resulting F₂ consist of 160 plants with kernel colors as shown in the following table.

Kernel Color Number
White   9
Dark red 12
Red 39
Light pink 41
Pink 59

How many additive alleles are required to explain the five phenotypes seen in the F₂?

Accepted Answer

Hi, everyone. Let's look at our next question. It says a plant with yellow flowers. Capital Y capital Y is crossed with a plant with red flowers, lowercase R, lowercase R. All of the F one offspring have yellow flowers. What can we conclude about the inheritance of flower color in these plants? Choice? A flower color is determined by multiple gene loci. B. Flower color is determined by a single gene locus with two alleys. C flower color is determined by a single gene locus with more than two alleys or choice D. It is impossible to determine the mode of inheritance from the information given. Well, we see two colors of flowers and then we see all the offspring of a cross between them with a single flower color. So when you see this result, every single one of the offsprings showing a single color, just one parental genotype or one parental phenotype. Excuse me, that indicates that the mode of inheritance is choice B, flower color is determined by a single gene locus with two all because you have this complete dominance, complete masking of one phenotype with the other. There's no intermediate phenotype, there's no mix of different types here. So when we look at our other answer, choices, uh choice, a flower color is determined by multiple gene loci. In that case, we'd expect to see some sort of combined or additive effect. Uh But here we just see this complete dominance. So that's why choice A isn't the best answer. Choy C says flower color is determined by a single gene locus with more than two alleys. Well, I suppose there could be a possibility. There's a third allele. We just looked at a cross between two colors here. But we're looking at what can we include from the information we have here, what we see in our problem and there's nothing in our problem that would indicate a third allele. So that's why choice C isn't our answer. And finally choice D it is impossible to determine the mode of inheritance from the information given. Well, that's not correct either because when you see that complete dominance occurring, that does suggest you have two all on the same gene locus. One completely masking the other. So again, the conclusion from the inheritance of flower color, when we see all the f one offspring with yellow flowers and a cross between yellow flowered plants and red flower plants is choice B. Flower color is determined by a single gene locus with two alleys. See you in the next video.

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