Which sterilisation method uses ultraviolet light to kill microorganisms?

• A. Glass bead steriliser
• B. Autoclave
• C. UV Sterilisation
• D. Boiling water

Answer: (C)

Ultraviolet light sterilisation uses UV-C radiation to damage the DNA or RNA of microorganisms. The energy from UV photons creates thymine dimers in DNA, which blocks replication and transcription, so the organism can’t survive or reproduce. This works best on exposed surfaces, in air, or in water where the light can reach directly. It doesn’t penetrate solids well and isn’t reliable for spores or shaded areas, so it’s not a universal sterilization method. The other methods rely on heat: dry heat via heated glass beads, moist heat under pressure in an autoclave, or simply boiling water. So the approach that uses ultraviolet light to kill microorganisms is ultraviolet sterilisation.