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    I was doing Q4 on this paper and i came across a hardy weinberg question:
    Polydactyly in cats is an inherited condition in which cats have extra toes. The allele for
    polydactyly is dominant.

    In a population, 19% of cats had extra toes. Use the Hardy-Weinberg equation to
    calculate the frequency of the recessive allele for this gene in this population.

    The answer is supposed to be 0.9.Somebody please help??

    The allele for polydactyly is dominant so this is p2 and 2pq which means you have to find q2. Turn 19% into a frequency - 19/100= 0.19 which is p2+2pq. As you want to find q2 do 1-0.19= 0.81 but now you want to find the allele which is q instead of the genotype so do the square root of 0.81 which is 0.9... Hope this helps, I'm not great at explaining!

    1-0.19 = 0.81= q^2 (recessive)
    Square root 0.81 to get q = 0.9

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