Essential Genetics 6th Edition by Daniel Hartl

Exercise 5

In the summer squash, Curcurbita pepo, the shape of the fruit in wildtype genotypes is a Frisbee-like flattened shape known as disc. A homozygous recessive mutation in either of two different genes results in spherical fruit. The fruit of the double recessive homozygous genotype is elongated, like an American football. Assuming independent assortment, what ratio of disc : sphere : elongate would be expected in the
generation of a cross between homozygous disc and homozygous elongate?