Chapter 3, Problem 32P

Three different pure-breeding strains of corn that produce ears with white kernels were crossed to each other. In each case, the F₁ plants were all red, while both red and white kernels were observed in the F₂ generation in a 9:7 ratio. These results are summarized in the following table.

		F1	F2
$\text{white}-\text{1}\times \text{white}-\text{2}$		red	9 red : 7 white
$\text{white}-\text{1}\times \text{white}-3$		red	9 red : 7 white
$\text{white}-2\times \text{white}-3$		red	9 red : 7 white
a.	How many genes are involved in determining kernel color in these three strains?
b.	Define your symbols and show the genotypes for the pure-breeding strains white-1, white-2, and white-3.
c.	Diagram the cross between white-1 and white-2, showing the genotypes and phenotypes of the F1 and F2 progeny. Explain the observed 9:7 ratio.