Texas A&M University (TAMU) BIOL206 Practice Exam 3

Using 70% alcohol as a germicidal agent does have some disadvantages, one of which is its tendency to evaporate relatively quickly. While alcohol is a commonly used disinfectant, its rapid evaporation can limit its contact time with surfaces or microorganisms, which is crucial for effective disinfection. If the alcohol evaporates too quickly, it may not remain on the surface long enough to effectively kill bacteria and viruses, reducing its overall efficacy as a disinfectant.

The concentration of alcohol is also important; for optimal antimicrobial activity, a solution that is 60-80% alcohol is generally preferred. It works best at 70% because water is also present, which slows the evaporation process and allows the alcohol more time to penetrate microbial cell walls, thus being more effective as a disinfectant. The other options do not accurately reflect disadvantages of using 70% alcohol.