The phenotypic dihybrid ratio is 9

The phenotypic dihybrid ratio is 9 - genes. Mendel...

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The phenotypic dihybrid ratio is 9:3:3:1–9 purple inflated, 3 purple constricted, 3 white inflated, and 1  white constricted. (Geneticists now test their results statistically to see if they approach the  theoretical 9:3:3:1 and usually use the  χ 2  [chi-square] test.)  Mendel drew a conclusion on the basis of his dihybrid crosses that is now known as  Mendel's  second law: the Law of Independent Assortment . It states that during gamete formation the  segregation of the alleles of one allelic pair is independent of the segregation of the alleles of other 
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Unformatted text preview: genes. Mendel confirmed this hypothesis further (as he did in the monohybrid crosses) by backcrossing the F 1 dihybrid to the recessive parent. The Punnett square for the backcross looks like this: The phenotypic ratio for the testcross is: 1:1:1:1; that is, 1 purple inflated:1 purple constricted:1 white inflated:1 white constrictedwhich indicates that the traits have separated and recombined independently of one another....
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