Luijckx et al. (2012) discovered that resistance to the bacterial parasite Pasteuria ramosa is genetically variable in the common freshwater crustacean Daphnia magna. To investigate the genetic basis of this variation, they crossed a completely resistant lineage to a completely susceptible lineage. All the F₁offspring were resistant. These offspring, when mature, were then crossed to each other to produce an F₂ generation. If resistance is the result of only a single gene with two forms (alleles), then resistant and susceptible  offspring should occur in a 3:13:1 ratio. Of 71 F2'_sF_2's tested, 57 were resistant and 14 were susceptible.

a. With these data, calculate the confidence interval of the proportion of resistant offspring. Does this interval include the proportion predicted if resistance is determined by a single gene?

b. Give two other values for the proportion that are also consistent with the data.

c. Test the genetic hypothesis. Are the results compatible with your findings in part (a)?

d. On the basis of these results, is it correct to conclude that a single gene in Daphnia magna underlies resistance to the bacterium?