Final answer:
NC likely refers to an error-correcting mechanism in DNA replication, where DNA polymerases use proofreading functions to prevent substitution mutations and maintain genetic stability.
Step-by-step explanation:
The question "How does NC prevent substitution?" likely refers to the prevention of nucleotide substitution in DNA, which could be addressed within the field of Biology. An accurate answer requires additional context, such as whether 'NC' refers to a specific protein or mechanism, or if it is a typo for another term.
Assuming 'NC' refers to an error-correcting mechanism in DNA replication, I can explain that DNA polymerases have proofreading abilities to correct errors during DNA replication to prevent substitution mutations. If a wrong nucleotide is incorporated, the enzyme stalls and removes the incorrect nucleotide before continuing replication.
This reduces the likelihood of substitution mutations, whereby one base pair is incorrectly replaced by another. The proofreading function is critically important for maintaining genetic stability and avoiding mutations that could lead to diseases.