30% of a population lacks the ability to taste the chemical PTC. Non-tasters are homozygouse recessive for this tasting gene. What percentage of the population are tasters and what percentage of the population are NOT heterozygous for this trait?

This question requires the knowledge of two equations from the Hardy-Weinberg Principle. p + q = 1 and p² + 2pq + q² = 1 where p = dominant allele, and q = recessive allele. Firstly we know from the question that 30% are non-tasters and so using equation 1, which means all remaining in the population are tasters. So 1 - 0.3 = 0.7 Which means that 70% of the popultation are tasters. Understanding of the equations is required to know that 2pq = the proportion of heterozygous Therefore next, we input values we know into this. 2 x (0.3) x (0.7) = 0.42 This tells us 42% of the population are heterozygous and so 100 - 42 = 58. So 58% of the population are not heterozygous.