Final answer:
UV radiation is the method that uses UV light for sterilization/disinfection, particularly employed in settings like biological safety cabinets. It kills microorganisms by causing mutations in their DNA but requires direct exposure as it cannot penetrate surfaces.
The correct answer is option d) UV radiation
Step-by-step explanation:
The sterilization/disinfection method that uses UV light is d) UV radiation. This physical method is employed in various settings, including biological safety cabinets. Ultraviolet (UV) light works by causing thymine dimers to form within DNA, which can lead to mutations and ultimately kill microorganisms. UV lamps are commonly incorporated into water purification systems and also used for surface sterilization in environments like surgical suites and biological safety cabinets. Germicidal lamps, for example, often emit UV light at a wavelength of around 260 nm, which is effective against microbes. However, it is important to note that UV light does not penetrate surfaces and cannot pass through materials like plastics or glass, so direct exposure to the light source is necessary for it to be effective.
Sterilization involves the complete removal or killing of all vegetative cells, endospores, and viruses. It can be achieved through physical means such as heat, pressure, filtration, or chemical methods using sterilants. UV light, a form of nonionizing radiation, is suitable for surface disinfection rather than filtration, which physically removes microbes. Filtration, on the other hand, does not kill microbes but removes them physically from samples.
Comparatively, methods such as autoclaving rely on moist heat to kill microbes including endospores which can survive boiling temperatures. Autoclaves increase temperatures above the boiling point of water to achieve this effect.
UV disinfection of water, meanwhile, is a purely physical process and does not remove dead microorganisms from the water. The world's largest UV water disinfection plant, treating New York City's drinking water, showcases the large-scale application of UV sterilization technology.