Final answer:
The genotype frequency for aa given that the A allele frequency is 0.7 is calculated using the Hardy-Weinberg principle, yielding a frequency of 0.09.
Step-by-step explanation:
The genotype frequency for aa given that the A allele frequency is 0.7 can be calculated using the Hardy-Weinberg principle. According to this principle, in a population in Hardy-Weinberg equilibrium, the frequencies of alleles and genotypes will remain constant from generation to generation.
The frequency of the aa genotype can be found using the equation p² + 2pq + q² = 1, where p is the frequency of the dominant allele (A) and q is the frequency of the recessive allele (a). Since p is given as 0.7, we can calculate q as 1 - p, which equals 0.3. Consequently, the frequency of the aa genotype, which is represented as q², is 0.3² or 0.09.