Scientists were examining the maize genome. They had two specimens: one control and one specimen that had undergone mutagenesis. They saw that the mutant specimen underwent a knockout caused by a nucleotide exchange in the DNA. When they compared gene sequences, they saw same number of nucleotide bases. Which type of mutation had most likely occurred? deletion insertion inversion substitution

substitution

Explanation:

A substitution is a point mutation where a nucleotide base (either adenine, guanine, thymine or cytosine) is replaced by a different base pair. In contrast to insertions or deletions, substitutions don't change the number of bases in the DNA sequence. Moreover, inversions are large genetic rearrangements where the genetic sequence is reversed. A substitution may have different effects: change a codon to another (changing the protein sequence when codons are translated into amino acids), produce a stop codon, cause synonymous mutations (i.e., neutral mutations that don't alter the amino acid sequence due to the degeneracy of the genetic code), etc.

the diploid number of chromosomes is sometimes represented by the symbol 2n. for the fruit fly, the diploid number is 8, which can be written as 2n = 8, where n represents twice the number of chromosomes in a sperm or egg cell.

affects the water bodies: excessive use of fertilizers causes eutrophication. the fertilizers which are used on plants affect the quality of land on which it is used, further causing erosion of soil. the fertilizers used on plants contain harmful chemical fumes which affect the environment.