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Corn genotypes

A) While examining an ear of corn, you notice that the kernels in the ear display two apparent phenotypes; yellow and white. inspired by your understanding that these represent different alleles of a single gene, you count the kernels of each type and you asses 347 yellow (Y) kernels and 111 white (y) kernels. if this ear of corn is an F2 hybrid, what was the genotype of its F1 parent? which allele is dominant?

b) For the ear of corn detailed above, test to see if the observed phenotype distribution fits the predictions of the genotype using the X2 test. what is your hypothesis? do the data permit you to accept the hypothesis? show work.

Solution Preview

347:111 is very close to a 3:1 ratio. In fact, it's 3.1:1. That's pretty close. Therefore, it looks like a nice F2 generation resulting from a heterozygote F1 cross.

Like this:

F1 parents were both Yy.

Y y

Y YY Yy

y Yy yy

Therefore, we have a 3:1 phenotypic ratio if we assume that Y is dominant.
YY and Yy are both yellow ...

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