Which of the following would be sufficient for the Hardy-Weinberg equation to accurately predict genotype frequencies from allele frequencies? p + q = 1 the population is not evolving due to natural selection. the population is not evolving due to any of the conditions that disrupt Hardy-Weinberg equilibrium. the population is infinitely large. in a village, if the proportion of individuals who have sickle-cell disease is 0.10, and the population is assumed to be at Hardy- Weinberg equilibrium, what is the expected frequency of the HbS allele? 0.32 0.18 0.90 0.01 in a village where the proportion of individuals who are susceptible to malaria (genotype HbA/HbA) is 0.31, and the population is assumed to be at Hardy-Weinberg equilibrium, what proportion of the population should be heterozygous HbA/HbS? Solution Ans. 5.5. Correct option- C Option A. Incorrect. A population NOT at Hardy-Weinberg (HW) equilibrium also has p + q= 1. Since the frequencies p, and q are calculated considering their relative abundance, their sum of always 1.0. However, the value of p and q changes over generations when population is evolving. The value of p and q remains constant over generations if the population is at HW equilibrium. Option B. Incorrect. Factors other than natural selection, like genetic drift, bottle-neck effect, etc. also disrupt HW equilibrium. So, even if natural selection does not occur, the population may evolve through genetic drift, etc. Option C. Correct. HW equation holds true when no factor causes evolution of the population. Option D. Incorrect. HW equation holds true when no factor causes evolution of the population. Being a large population do not exclude the possibilities of evolution. Ans. 5.6. Normal, dominant allele = HbA Mutant, recessive allele = Hbs Normal, homozygous genotype = HbA HbA - susceptible to malaria Normal, heterozygous genotype = HbA Hbs - it is a carrier, but unaffected by disease Recessive, affected genotype = Hbs Hbs - affected with sickle-cell disease Now, Hardy- Weinberg Equation for 2 allele system (for a population at HW equilibrium) p + q = 1 - equation 1 (p + q)2 = p2 + q2 + 2pq = 1 - equation 2 Where, p = allelic frequency of dominant allele HbA q = allelic frequency of recessive allele HbS p2 = genotypic frequency of HbA HbA q2 = genotypic frequency of Hbs Hbs 2pq = genotypic frequency of HbA Hbs Given, Frequency of Hbs Hbsindividuals = q2 = 0.10 Or, q2 = 0.10 Or, q = (0.10)1/2 = 0.316 = 0.32 ; [Note: (0.10)1/2 is under root (.010)] Hence, frequency of allele HbS = q = 0.32 Correct option. A. Ans. 5.7 Given, Frequency of HbA HbAindividuals = p2 = 0.31 Or, p = (0.31)1/2 = 0.55677 Hence, frequency of HbA allele = 0.55677 Putting the value of p in equation 1- p + q = 1 or, q = 1 – 0.55677 = 0.44323 Hence, q = 0.44323 Now, Frequency of the heterozygotes (HbA Hbs) = 2 pq = 2 x (0.55677) x (0.44323) = 0.493 Hence, frequency of heterozygotes = 0.493 % of heterozygotes = 49.3 %.