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Monohybrid Problems Genetics

  1. Apr 19, 2005 #1
    Chickens with shortened wings and legs are called creepers, when creepers are mated to normal birds, they produce half creepers and half normal birds. When creepers aremated to creepers they produce 2 creepers to 1 normal. Crosses between normal birds produce only normal offspring. How must thesee results be explained?

    Determine the geotypes of the bull and the 3 cwos. Hornless is recessive when Cow A is mated with the bull, the calves are all hornless. When cow B is mated with the bull the calvbes are all hornless. When cow C is mated with the bull a horned calf results. Cow A is horned. Cow B is hornless and Cow C is hornless

    Thanks any help will be appreciated
  2. jcsd
  3. Apr 19, 2005 #2
    It is difficult to give hint without answering the question but here goes:

    Call the creeper allel C and the normal one N, then a creeper may have genotype CN or CC, normal ones could be CN or NN. See what genoptypes the offspring would have assuming the different possible genotypes of the parents (you will have to assume that one genotype is letal in order to explain the "2 creeper 1 normal" frequency of the offspring of creepers corssed with creepers).

    Call hornless allel H and the horns allel N, since hornless is recessive you know that all hornless cows must have genotype HH, using the results of the crossings you can easily figure out whether the others are HN or NN.
  4. Apr 20, 2005 #3


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    Karma, first figure out which trait is dominant and if the parent are heterozygous or homozygous

    No you don't. Creeper is probably dominant and the parent are probably heterozygous
  5. Apr 20, 2005 #4
    but then you would get 3 creeper 1 normal (not 2:1)
  6. Apr 20, 2005 #5


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    My bad. Maybe I should avoid answering question right after I wake up.
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