What is the result of a substitution mutation?
The new amino acid is always the same as the original amino acid.
The new amino acid is always different from the original amino acid.
O The new amino acid may be the same as the original amino acid or it may be different.

The new amino acid may be the same as the original amino acid or it may be different.

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).