Questions and Answers
Decimal reduction time is the time in minutes in which __________ of the population at a given temperature will be killed.
90%
Which of these conditions is likely to interfere with the effectiveness of an antiseptic or disinfectant?
You conclude from these results that __________.
the compound is fungistatic
An antiseptic is used to remove microbes from __________.
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Which of these is NOT a characteristic of the autoclave?
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A chemical that reduces spoilage in fruit by destroying fungi but does NOT appear to affect other microbes would be called a __________.
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Which of the following correctly describes antisepsis?
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Which treatment is most effective against S. enterica?
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The DRT for a particular bacterial species at 60°C is 30 minutes. How long would it take at this temperature to remove 99.9% of this bacterial population?
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Which of the following is true of an antimicrobial substance with a microbial death rate of 90% after 1 minute?
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Which of the following are NOT major targets for action of antimicrobials?
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Which of the following treatments achieves sterilization?
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Operating rooms may receive ventilation from air that has passed through __________ filters to remove microorganisms.
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__________ bacteria may survive pasteurization.
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The most likely explanation for pasteurized milk spoiling is __________.
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Packages of milk and coffee creamers may be stored without refrigeration if they have been sterilized by __________.
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Which of the following is LEAST likely to be damaged by exposure to gamma radiation?
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Pasteurization was first used by Pasteur to control spoilage of __________.
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Sterilization is the __________.
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Which of the following types of radiation is the LEAST effective control method against microorganisms?
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Which type of radiation is LEAST effective in killing microbes?
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All of the following methods are used for food preservation EXCEPT __________.
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Which of the following is an appropriate strategy for preparing and sterilizing a medium for growing fastidious bacteria?
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How were the creamer products treated to eliminate microbial growth and prevent spoilage?
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Which one of the following physical methods of microbial control is bactericidal?
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For control of microbial growth on a surface, which of these conditions is LEAST likely to interfere with the effectiveness of an antiseptic or disinfectant?
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Which term refers to an agent that inhibits bacterial growth?
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Study Notes
Microbiology Concepts and Definitions
- Decimal Reduction Time (DRT) is the duration required to kill 90% of a microbial population at a specific temperature.
- Antiseptics are agents that remove microbes from living tissue, commonly used on skin prior to injections.
- A fungistatic compound inhibits fungal growth without killing them, as seen in reduced fungal weight on treated apples compared to untreated ones.
- A fungicidal agent destroys fungi, effectively reducing spoilage in fruit without affecting other microorganisms.
Antimicrobial Agents and Effects
- The presence of biofilms significantly decreases the effectiveness of antiseptics and disinfectants.
- Heat treatment at 52°C is the most effective method against Salmonella enterica, with a DRT of 2 minutes.
- Antimicrobial substances often display a 90% death rate; after one minute, 10% of the original microbial population remains.
Sterilization and Pasteurization Techniques
- Autoclaves use high pressure and moist heat for sterilization, not requiring long exposure times.
- Pasteurization traditionally aimed to control spoilage in wine but has broader applications in food safety, like milk preservation.
- Thermoduric bacteria can survive pasteurization processes but face challenges at refrigeration temperatures.
- Ultra-high-temperature (UHT) treatment allows for storage of dairy products without refrigeration by eliminating microbial growth.
Radiation and Microbial Control
- Gamma rays are highly effective, while microwaves are the least effective method of all types of radiation in controlling microbial populations.
- Prions are notably resistant to heat and various radiation treatments compared to other microorganisms like viruses and bacteria.
General Microbial Control Facts
- Direct flaming is not a method typically used for food preservation compared to methods like desiccation and commercial canning.
- Bacteriostatic agents inhibit bacterial growth, while bactericidal agents kill bacteria.
- HEPA filters are used in operating rooms to filter out microorganisms from the air for infection control.
Key Takeaways for Laboratory Practices
- For media requiring heat-labile solutions, prepare and autoclave the medium before adding sensitive ingredients.
- Environmental conditions like warm temperatures do not significantly hinder antiseptic effectiveness compared to high microbial numbers or biofilms.
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Description
Test your knowledge on key concepts from Microbiology Chapter 7 with these flashcards. Focus on terms like decimal reduction time and factors affecting antiseptic effectiveness. Perfect for reinforcing your understanding of microbial control.
