In maize, the gene for leaf color has two alleles, recessive g for green leaves and dominant G for purple leaves, and the gene for stalk height has two alleles, recessive s for short stalk and dominant S for tall stalk. A plant with green leaves and a short stalk was crossed to a plant with purple leaves and a tall stalk. All the F1 plants from this cross had purple leaves and tall stalks. When they were backcrossed to plants with green leaves and short stalks, they produced an F2 in which, among a total of 200 plants, four phenotypic classes were observed: (1) green leaves, short stalks, 75; (2) purple leaves, tall stalks, 79; (3) green leaves, tall stalks, 24; and (4) purple leaves, short stalks, 22.

(a) What is the evidence that the genes for leaf color and stalk height are linked?

(b) What is the linkage phase of the dominant and recessive alleles of these two genes in the F1 plants?

(c) Among the F2 plants, what is the frequency of recombination?

(d) What is the distance in centiMorgans between the leaf color and stalk height genes?