Answer: circulatory system
Explanation:
Allele frequency is a measure of the relative frequency of an allele on a genetic locus in a population.
Usually it is expressed as a proportion or a percentage.
In population genetics, allele frequencies show the genetic diversity of a species population or equivalently the richness of its gene pool.
The frequencies of all the alleles of a given gene often are graphed together as an allele frequency distribution histogram.
Population genetics studies the different "forces" that might lead to changes in the distribution and frequencies of alleles - in other words, to evolution.
Besides selection, these forces include genetic drift, mutation and migration.
If scientists believe that the newly discovered gene has two alleles A and a and that the alleles show incomplete dominance, the best way to prove this is to look for subjects who are homozygous with respect to the different alleles. The offsprings will all have the genotype of Aa and if indeed, the alleles show incomplete the dominance, the traits of the first generation will not manifest completely but a mixture of two will.