Question

Suppose a population is carrying a condition controlled by two alleles: R (dominant) and r (recessive). If the frequency of the r allele is 15%, and the frequency of the R allele is 85%, what will be the frequency of the RR genotype, assuming evolution is not occurring

A. 72.25 percent

B. 25.5 percent C. 12.75 percent D. 2.25 percent

Answer 1

The answer is (A) 72.25 percent. For an offspring, there are four possible outcomes: RR, rr, Rr, and rR (first and second letters corresponding to maternal and paternal contributions). To calculate the likelihood of each outcome, we multiply the likelihood of the two independent contributions. For the RR outcome, that is 0.85 times 0.85, which equals .7225 or 72.25%.