Dihybrid Crosses
In some cases, we want to predict the inheritance with two different genes. The law of independent assortment states
that the alleles of two (or more) different genes get sorted into gametes independently of one another. So how do we
determine this? Dihybrid Crosses!
Example: In pea plants, round seeds are dominant ( R ) and wrinkled seeds are recessive ( r ). Yellow seeds are dominant
(Y) and green seeds are recessive (y). A homozygous green plant is crossed with a homozygous yellow plant. Show the F1
and F2 genotypic and phenotypic ratios.
Parent: ________________________
Gametes:
x
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Punnett Square
F1 generation
Gametes:
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Punnett Square:
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x
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