You are investigating 4 recessive alleles in corn. They are whimpy ears (w), striped leaves (s), shriveled kernels (k), and red tassels (r). Their dominant counterparts are represented by the “+” symbol. A plant that is homozygous recessive for all four genes (ww ss kk rr) is crossed with a plant that is homozygous dominant for all four genes (++ ++ ++ ++). The F₁ progeny (w+ s+ k+ r+) are then testcrossed with another plant. A total of 1000 F₂ progeny were produced. The F₂ progeny display the following phenotypes.

a.     Calculate the recombination frequencies between each pair of genes. (HINT: you will calculate 6 recombination frequencies – determine where each pair of genes experienced a crossover to produce the observed offspring).

b.     Draw a chromosome map for these genes if they are linked.