What type mutation are most harmful to an organism

type 1

Explanation:

Because an insertion or deletion results in a frame-shift that changes the reading of subsequent codons and, therefore, alters the entire amino acid sequence that follows the mutation, insertions and deletions are usually more harmful than a substitution in which only a single amino acid is altered.

as in mitosis, dna replication occurs during interphase.   in meiosis, it occurs specifically in s phase of interphase 1.