Atrue-breeding caffeine-free plant carrying the allele z2 for marker z, was crossed with a true-breeding caffeine-producing plant of commercial value (with the z1 allele for marker z). 100% of the f1 individuals were able to produce caffeine. f1 was selfed, producing f2 plants with the following proportions of phenotype/genotype:

49.02% caffeine-producing, genotype z1z2
24.99% caffeine-producing, genotype z1z1
24.01% caffeine-free, genotype z2z2
0.99% caffeine-producing, genotype z2z2
0.98% caffeine-free, genotype z1z2
0.01% caffeine-free, genotype z1z1

a) what is the genotype for marker z in the parental caffeine-free plant?
b) what is the genotype for marker z in the parental caffeine-producing plant?
c) what is the genotype for marker z in the f1 plants?
d) what is the genetic distance between the cs gene and marker z?
tip: do the punett ! use cs+ for caffeine-producing, and cs- for caffeine-free alleles.