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B. In the following problems: Red coat {R} and long {L} nose are dominant in dogs, white {r} and short {l} nose are recessive.

1. When a red coated, long nosed dog is crossed with a white, short nosed dog: some white, short nosed puppies occur. Give the genotypes of the parents and the F1. What phenotypes could occur in the offspring?

2. If two red coated, long nosed dogs are breed and some white, short nosed puppies appear, what phenotypes ratio will be parent in the F1?

3. A homozygous red coated, long nosed dog is bred with a white, short nosed dog, what genotypes and phenotypes will appear in their offspring?

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  • 1 decade ago
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    1. OK so a red coated dog could be Rr or RR, so for now we now that one parent is R_ and it has a long nose. So parent A: R_L_ for now.

    Parent b is white with a short nose, both recessive traits, so we can be certain it's genotype is rrll.

    Since the some offspring are white with short noses, parent a has to be a carrier for the recessive traits. So, final answer:

    Parent A: RrLl

    Parent B: rrll

    P1 Genotypes: RrLl x rrll

    P1 Phenotypes: red coat with long nose x white coat with short nose

    Gametes: RL, Rl, rL, rl x rl, rl, rl, rl

    So make a punnett square for the P1 and list out the phenotypes for F1 (red coat with short nose, red coat with long nose, white coat with short nose and white coat with long nose

    2) Red coats with long nose is RrLl or RRLL, but I don't really get what the question is asking for.

    3) Homozygous red coat with long nose is RRLL, white short nose dog must be rrll. The genotypes of the oF1 will be 100% RrLl and for phenotypes 100% red coat with long nose.

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