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Homework Help: Incomplete Dominance Question Grade 11 Need an biology expert

  1. Mar 16, 2012 #1
    1. The problem statement, all variables and given/known data

    Hey guys...

    The palomino horse results from the combination of two incompletely dominant genes, one codes for the colour chestnut and the other for cream. Determine the expected genotypic and phenotypic ratios for the following crosses:

    a.)chestnut and cream
    b.)palomino and cream
    c.) palomino and palomino

    Please this is the only question I didn't understand for my homework.. However I got 100% for phenotype for all options... Please correct me if I'm wrong and tell me what I'm doing right and wrong but mostly wrong :)

    2. Relevant equations

    What :S :?

    3. The attempt at a solution

    Let PP represent the allele for palomino.
    Let PC1 represent the allele for cream.
    Let PC2 represent the allele for chestnut.



    Genotype: 50% Cream; 50% Chestnut
    Phenotype: 100% PC1PC2



    Genotype: 50% Cream; Palomino 50%
    Phenotype: 100% PPPC1



    Genotype: 100% Palomino
    Phenotype: 100% PPPP
  2. jcsd
  3. Mar 17, 2012 #2


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    Science Advisor
    2017 Award

    A few points:

    1) When the question asks about about genotype ratios, it's talking about the different combinations of alleles. For example, 50% PC1PC2, 50% PC1PC1 is a genotype ratio. A phenotype ratio would describe the numbers of horses of each color, for example, 50% palomino, 50% cream.

    2) Pp is not the allele for palomino. In fact, phenotypes are not represented by a single allele. Rather, phenotypes are associated with pairs of alleles (e.g. PC1PC1 gives the cream phenotype, whereas Pc2Pc2 gives the chesnut phenotype). Read the question again, focusing on the first two sentences. What is the genotype associated with the palomino phenotype? If you still don't understand, you may need to re-read the section in your textbook on incomplete dominance.
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