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Offspring phenotypes for Guinea Pigs

In guinea pigs, dark coat color (C) is dominant over albino (c), and short hair (S) is dominant over long hair (s). The genes for these two traits show independent assortment. By evaluating the possible crosses, determine the most probable genotypes for the parents of each of these seven crosses:

parental phenotypes short dark long dark short albino long albino
a)dark short x dark short 89 31 29 11
b)dark short x dark long 18 19 0 0
c)dark short x albino short 20 0 21 0
d)albino short x albino short 0 0 28 9
e)dark long x dark long 0 32 0 10
f)dark short x dark short 46 16 0 0
g)dark short x dark long 29 31 9 11

Solution Preview

The key in this problem is to work backwards. See the parental phenotypes first and depending on the dominant gene write down the probable genotype.
eg. in a) Since the genotypes of both are dark short - the genotype has to be

C_S_ x ...