Multiple Choice
In the context of food safety, what is the maximum amount of time that food can safely remain in the temperature danger zone (between 4°C and 60°C) before it must be discarded?
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1. Introduction to Microbiology
Introduction to Microbiology
Multiple Choice
Which of the following is a limitation of using UV radiation for disinfection?
A
UV radiation is effective in the absence of direct exposure to microorganisms.
B
UV radiation has poor penetration through opaque or solid materials.
C
UV radiation leaves toxic chemical residues on surfaces.
D
UV radiation is highly effective at killing bacterial spores in deep layers.
Verified step by step guidance1
Understand the mechanism of UV radiation disinfection: UV light kills microorganisms primarily by damaging their DNA, which prevents replication and leads to cell death.
Recognize that UV radiation requires direct exposure to be effective because it cannot penetrate solid or opaque materials; microorganisms shielded by such materials will not be affected.
Evaluate each option by comparing it to the known properties of UV radiation: it does not leave chemical residues, and it is generally less effective against bacterial spores, especially those not directly exposed.
Identify that the limitation is related to penetration ability, meaning UV radiation cannot disinfect areas that are not directly exposed or are covered by opaque substances.
Conclude that the correct limitation is that UV radiation has poor penetration through opaque or solid materials, which restricts its use to surface disinfection where direct exposure is possible.
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