Researchers studying a small milkweed population note that some plants produce a toxin and other plants do not. They identify the gene responsible for toxin production. One allele (t1) codes for an enzyme that makes the toxin, and another allele (t2) codes for a nonfunctional enzyme that cannot produce the toxin. Heterozygotes produce an intermediate amount of toxin. The allele frequency of t1 is determined to be 0. 6 and the allele frequency of t2 is 0. 4. What is the expected frequency of heterozygotes if the population is in hardy-weinberg equilibrium?.