Answer:
A. 18
Step-by-step explanation:
Given that the Hardy-Weinberg equilibrium:
p² + 2pq + q² = 1
and p + q = 1
We can determine the percentage of the individuals would be expected to be heterozygous for this gene in the next generation.
Let the homozygous recessive individuals, let say "aa" = q²= 81%
Let the homozygous dominant individuals = AA = p²
Let the heterozygous individuals = Aa = 2pq
The frequency of 'a' allele which means q²= 0.81,
by definition; if
q²= 0.81
q= 0.9
Since q equals to the frequency of the 'a' allele, then the frequency is 90%
The frequency of the 'A' allele from the homozyous dominant individual can be determined since q = 0.9
p+q = 1
p+0.9 = 1
p = 1 - 0.9
p = 0.1
Frequency of A allele by definition is said to be 10%
Now, to determine the percentage of the individuals that is expected to be heterozygous for the next generation, we have;
2pq = (2 × 0.9 × 0.1 )
= 0.18
= 18%