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Determine the phenotypes of progrency

  1. Nov 1, 2005 #1
    Hi,

    My Question:

    In poultry, the dominant alleles for a rose comb (R) and a pea comb (P), if present together, give a walnut comb. The recessive alleles of each gene, when present together in a homozygous state, give a single comb. What will be the comb characters of the offspring of the following cross?

    a. R/RP/p´r/rP/p

    I'm not sure what to do. Am I supposed to develop a combination of crosses and then put them in a punnett square to help determine the phenotypes:confused:

    Thank You :smile:
     
  2. jcsd
  3. Nov 1, 2005 #2

    iansmith

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    It is basicly a 16 square punnett square of the cross given in a. and you have to give the character of the offsprings.
    To get you started, the possible combination of one of the parent is as follow:
    RP Rp RP Rp

    So have to determine the combination of the other parent and then mix both parental combination.
     
  4. Nov 1, 2005 #3
    So you mean like this

    View attachment Table.doc
     
    Last edited: Nov 1, 2005
  5. Nov 1, 2005 #4

    Moonbear

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    Not quite. Go back to that very first problem set you posted here where we went through how to set up a Punnett Square for two traits and refresh your memory of how to set those up. It's the same thing here. iansmith got you started for one parent.
     
  6. Nov 1, 2005 #5
    Hi,

    So it would be a 9:3:3:1 type combination?

    If so wouldn't it be the same answer for the different type of combinations for this cross

    • r/rP/P´R/rP/p
     
  7. Nov 2, 2005 #6

    Moonbear

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    9:3:3:1 is the ratio you get with a dihybrid cross (when both parents are heterozygous for both traits). What are your gametes for each parent?
     
  8. Feb 17, 2010 #7
    Hi . Help me ? which one correct .
    In poultry, the dominant alleles for rose comb (R) and pea comb (P), if present together, give a walnut comb. The recessive alleles of each gene, when present together in a homozygous state, give a single comb. What will be the comb characters of the offspring of the following cross: R/R P/p x r/r P/p?
    A. 1/4 walnut (R/r P/-) : 3/4 rose (R/r p/p)
    B. 3/4 walnut (R/r P/-) : 1/4 rose (R/r p/p)
    C. 1/2 walnut (R/r P/-) : 1/2 pea (r/r P/-)
    D. 1/4 walnut (R/r P/-) : 1/4 rose (R/r p/p) : 1/4 pea (r/r P/-) : 1/4 single (r/r p/p)
    E. 1/2 pea (r/r P/-) : 1/2 single (r/r p/p)
    Thank You very much
     
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