Answer:
The type of mutation that occurs when in the DNA strand there is a change from guanine to cytosine is a nonsense mutation, since the triplet that should encode the amino acid encodes a stop codon and the protein cannot be completely synthesized.
Explanation:
The nonsense mutation consists of a change in one of the bases of the stranded DNA, which is transcribed into an altered mRNA, producing a stop codon, instead of an amino acid.
In the table it is observed that the CCA codon is a stop codon that cuts off the protein synthesis prematurely, leaving it incomplete and probably non-functional.
Sometimes this type of mutation can alter the sequence of amino acids but the protein may be complete enough to partially fulfill its function.
Answer: The frequency of brown beetles is 0.32.
Explanation: The frequency of A1 allele is 0.8. As p+q=1, or the sum of dominant and recessive frequencies equals 1 or 100%:
1 - 0.8 = 0.2
In Hardy-Weinberg principle,

2pq represents the frequency of heterozygote individuals, so:
genotype A1A2 = 2*0.8*0.2 = 0.32.
Thus, the frequency of brown beetles (A1A2) in the population is 0.32.