[Campbell Biology P.554] In a fruit fly population that is in Hardy-Weinberg equilibrium, te... | Practice Question

In a fruit fly population that is in Hardy-Weinberg equilibrium, tests show that 70% of the gametes produced contain the A1 allele for a particular gene. What proportion of the flies in this population are expected to carry both the A1 and A2 alleles?

  • A: 0.70
  • B: 0.49
  • C: 0.42
  • D: 0.21

Explanation

In Hardy-Weinberg equilibrium, if p is the frequency of allele A1 and q is the frequency of allele A2, then p + q = 1. We are given p = 0.70. Therefore, q = 1 - 0.70 = 0.30. The proportion of flies carrying both A1 and A2 alleles are the heterozygotes A1A2 , whose frequency is represented by 2pq. So, 2pq = 2 0.70 0.30 = 2 0.21 = 0.42.