Irradiation can directly impair critical cell functions or components of DNA.

• A. True
• B. False
• C. Only indirectly forms radiolytic products.
• D. It has no effect on cells.

Answer: (A)

Direct ionization of DNA and essential cellular components by irradiation can disrupt replication, transcription, and basic cell functions. When radiation directly hits DNA, it can cause strand breaks, base damage, and crosslinks, and it can also damage proteins, membranes, and enzymes, leading to impaired viability. While indirect damage from radiolysis of water–produced reactive species contributes significantly to overall effects, the direct interactions alone are enough to impair critical cellular functions. That’s why the statement is true. The idea that damage only comes from indirect radiolytic products is incomplete, and the notion that irradiation has no effect on cells is incorrect.