Damage to DNA can never be repaired.

• A. Sometimes
• B. True
• C. False
• D. Not sure

Answer: (C)

DNA damage is not irreparable; cells have multiple repair systems to fix different types of lesions. For example, base excision repair fixes small chemical changes to bases, nucleotide excision repair removes bulky adducts and UV-induced dimers, mismatch repair corrects replication errors, and double-strand breaks are handled by homologous recombination or non-homologous end joining. There are also pathways for repairing single-strand breaks and other common damages. While outcomes can vary and repair isn’t flawless in every case, the idea that damage can never be repaired is incorrect.