Wild-type canaries are yellow. A mutant allele of the color gene causes white fe

Question

Wild-type canaries are yellow. A mutant allele of the color gene causes white feathers in heterozygotes that carry this mutant allele. Two white canaries are crossed. They produce progeny in a 1:2 ratio of yellow to white. If the yellow progeny are crossed to each other, they are true-breeding, yielding only yellow progeny. If the white progeny are crossed to each other, they again produce a 1:2 ratio of yellow to white offspring.

(a) Explain this 1:2 ratio using terminology learned in class. Within your explanation propose genotypes for the above yellow and white canaries. Define your alleles.

(b) If you were to cross a yellow canary to a white canary, what phenotypic ratio would you predict to see in the progeny?

Explanation / Answer

Wild type is yellow let genotype to be YY, with mutant M it gives YM that is white. now we crosses two white YM X YM we will get as below

SO YELLOW TO WHITE 1:2 RATIO. So here if the yellow progeny crossed each other they will give all four YY that is true yellow wild type. if white Ym are crossed again will get 1:2 ratio yellow and white. Now let see cross of white to yellow. this could be example of co dominant so one mutant gene togther with another only show a different colour

SO YELLOW TO WHITE RATIO WOULD BE 1:1

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