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    (Original post by iamspiderman)
    I need help with this question for question 1 a I know that the short allele is dominant and the black allele is also dominant

    but how to do b??? I cant do it
    9 short black hair, 3 short white hair, 3 long black hair, 1 long white hair.

    9 : 3 : 3 : 1 is a classic Mendelian ratio, so any time you cross two pure-breeding parents with two traits (one completely dominant and one completely recessive), you'll get this pattern. Have you done genetic crosses?
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    (Original post by iamspiderman)
    Yeah I actually figured how to work it out now thanks!

    I'm stuck with this Q though:

    If one white , single combed cockerel is crossed with several single combed, dark feathered hens. What is the probability that the cockerel will only have white offspring ?
    I don't think I have enough information to work that out? Does the question tell you anything else? Like where the genes are located or which is dominant? :/
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    (Original post by iamspiderman)
    Oh yeah sorry

    It's an extension of another question
    The genotype for the cockerel is ppwW and for the hens are ppww

    Where the
    White is W
    Dark w
    Pea combed P
    Single combed p

    And white is dominant and since is recessive


    I just don't get how to find the probability.. Cos it's one cockerel with several hens ..
    If all of the hens are the same phenotype (homozygous for dark), the factor that determines colour will be whether the offspring gets W or w from the cockerel.

    The probability of getting white offspring is 0.5, so I guess probability of getting only white offspring is just 0.5 to the power of the number of hens the cockerel mates with.
 
 
 
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