DNA replicates every time a cell undergoes mitosis for growth and repair or meiosis for gamete production. This continues to occur throughout the life of the organism. Mutations or mistakes in the copying of the DNA are common and cells contain mechanisms to repair these mistakes. Copying errors can be repaired by enzymes such as DNA polymerase that can use the undamaged strand of DNA in the double helix as a template to fix and replace the incorrect damaged base sequence.
This is from HSC online!
Next time say that it's from the option topic because this scared me for one second! This isn't taught in the core modules i believe, and it's a dotpoint in genetics