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Microbiology Chapter 7 Flashcards
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Microbiology Chapter 7 Flashcards

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@WellReceivedSquirrel7948

Questions and Answers

Which of the following is the best method to sterilize heat-labile solutions?

  • Freezing
  • Membrane filtration (correct)
  • Dry heat
  • Pasteurization
  • Autoclave

    • Which of the following best describes the pattern of microbial death?

  • The pattern varies depending on the antimicrobial agent.
  • The pattern varies depending on the species.
  • Not all of the cells in a culture are killed.
  • All the cells in a culture die at once.
  • The cells in a population die at a constant rate. (correct)

    • Which of the following chemical agents is used for sterilization?

  • Alcohol
  • Phenolics
  • Soap
  • Chlorine
  • Ethylene oxide (correct)

    • Which of the following substances is used for surgical hand scrubs?

    <p>Chlorhexidine</p> Signup and view all the answers

    Which of the following pairs of terms is mismatched?

    <p>Bacteriostatic – kills vegetative bacterial cells</p> Signup and view all the answers

    The antimicrobial activity of chlorine is due to which of the following?

    <p>The formation of hypochlorous acid</p> Signup and view all the answers

    Which of the following regarding antimicrobial control agents is FALSE?

    <p>Some agents inactivate viruses by attacking cell membrane lipids.</p> Signup and view all the answers

    Which of the following does NOT achieve sterilization?

    <p>Pasteurization</p> Signup and view all the answers

    Which of the following is a limitation of the autoclave?

    <p>It cannot be used with heat-labile materials.</p> Signup and view all the answers

    An agent used to reduce the number of bacteria on a toilet would most accurately be called a(n)

    <p>Disinfectant</p> Signup and view all the answers

    Application of heat to living cells can result in all of the following EXCEPT

    <p>Decreased thermal death time.</p> Signup and view all the answers

    Which of the following disinfectants acts by disrupting the plasma membrane?

    <p>Bisphenols</p> Signup and view all the answers

    Oxidizing agents include all of the following EXCEPT

    <p>Glutaraldehyde</p> Signup and view all the answers

    Disinfection of water is achieved by all of the following EXCEPT

    <p>Peracetic acid</p> Signup and view all the answers

    All of the following substances are effective against nonenveloped viruses EXCEPT

    <p>Alcohol</p> Signup and view all the answers

    Which of the following methods is used to preserve food by slowing the metabolic processes of foodborne microbes?

    <p>Freezing</p> Signup and view all the answers

    Which concentration of ethanol is the most effective bactericide?

    <p>70 percent</p> Signup and view all the answers

    All of the following factors contribute to hospital-acquired infections EXCEPT

    <p>None of the answers is correct; all of these factors may contribute to hospital-acquired infections.</p> Signup and view all the answers

    Which of the following treatments is the most effective for controlling microbial growth?

    <p>They are equivalent treatments.</p> Signup and view all the answers

    Which of the following could be used to sterilize plastic Petri plates in a plastic wrapper?

    <p>Gamma radiation</p> Signup and view all the answers

    Which of the following regarding antimicrobial control agents is FALSE?

    <p>A true antimicrobial control agent is equally effective against both bacteria and viruses.</p> Signup and view all the answers

    In Figure 7.1, what is the thermal death time?

    <p>60 minutes</p> Signup and view all the answers

    In Figure 7.1, the thermal death point for this culture is

    <p>The answer cannot be determined based on the information provided.</p> Signup and view all the answers

    In Figure 7.1, the decimal reduction time (D value) for the culture is approximately

    <p>10 minutes</p> Signup and view all the answers

    Which of the following results in lethal damage to nucleic acids?

    <p>Heat, radiation, and some chemicals</p> Signup and view all the answers

    Which of the following pairs is mismatched?

    <p>Alcohols – open wounds</p> Signup and view all the answers

    In Table 7.1, which compound was the most effective against Staphylococcus?

    <p>C</p> Signup and view all the answers

    In Table 7.1, which compound was the most effective against E.coli?

    <p>The answer cannot be determined based on the information provided.</p> Signup and view all the answers

    In Table 7.1, which compound was bactericidal?

    <p>The answer cannot be determined based on the information provided.</p> Signup and view all the answers

    In Table 7.2, which preservative is most effective?

    <p>Sodium benzoate</p> Signup and view all the answers

    An iodophor is a(n)

    <p>Iodine mixed with a surfactant</p> Signup and view all the answers

    Ethylene oxide

    <p>Is a sterilizing agent</p> Signup and view all the answers

    All of the following substances are used to preserve foods EXCEPT

    <p>Biguanides</p> Signup and view all the answers

    In Table 7.3, which disinfectant is the most effective at stopping bacterial growth?

    <p>Doom</p> Signup and view all the answers

    In Table 7.3, which disinfectant was bactericidal?

    <p>Mortum</p> Signup and view all the answers

    In Table 7.3, which disinfectant was most effective against Salmonella?

    <p>The answer cannot be determined based on the information provided.</p> Signup and view all the answers

    All of the following are effective for destroying prions EXCEPT

    <p>Boiling</p> Signup and view all the answers

    Which of the following pairs is mismatched?

    <p>Ultraviolet radiation – desiccation</p> Signup and view all the answers

    All of the following are methods of food preservation EXCEPT

    <p>Microwaves</p> Signup and view all the answers

    The preservation of beef jerky from microbial growth relies on which method of microbial control?

    <p>Desiccation</p> Signup and view all the answers

    If you were preparing nutrient agar at home and did not have an autoclave, what could you use to sterilize the nutrient agar?

    <p>Pressure cooker at 121°C for 15 minutes</p> Signup and view all the answers

    Bone and tendons for transplant are decontaminated by

    <p>Supercritical fluids</p> Signup and view all the answers

    Which one of the following is most resistant to chemical biocides?

    <p>Gram-negative bacteria</p> Signup and view all the answers

    Any process that destroys the non-spore forming contaminants on inanimate objects is sterilization.

    <p>False</p> Signup and view all the answers

    Desiccation is a reliable form of sterilization.

    <p>False</p> Signup and view all the answers

    The thermal death time is the time needed to kill all the bacteria in a particular culture at a certain temperature.

    <p>True</p> Signup and view all the answers

    Pseudomonas has been found growing in quaternary ammonium compounds (quats).

    <p>True</p> Signup and view all the answers

    Moist heat destroys organisms by denaturing proteins.

    <p>True</p> Signup and view all the answers

    Some antimicrobial chemicals are considered to be disinfectants and antiseptics.

    <p>True</p> Signup and view all the answers

    The pH of the medium has no effect on the activity of the disinfectant being applied.

    <p>False</p> Signup and view all the answers

    Ultraviolet light (UV) causes irreversible breaks in DNA strands.

    <p>False</p> Signup and view all the answers

    Autoclaving is the most effective method of moist heat sterilization.

    <p>True</p> Signup and view all the answers

    Microorganisms placed in high concentrations of salts and sugars undergo lysis.

    <p>False</p> Signup and view all the answers

    Study Notes

    Sterilization and Microbial Control Methods

    • Membrane filtration is the best method for sterilizing heat-labile solutions.
    • Microbial death occurs at a constant rate, not all at once.
    • Ethylene oxide is an effective chemical agent for sterilization.
    • Chlorhexidine is commonly used for surgical hand scrubs.

    Antimicrobial Terminology

    • Bacteriostatic agents inhibit growth without killing bacteria.
    • Hypochlorous acid formation is responsible for chlorine's antimicrobial activity.
    • Effective disinfectants disrupt microbial cell membranes, such as bisphenols.

    Dysfunctions and Misconceptions

    • Pasteurization does not achieve complete sterilization.
    • Autoclaves cannot be used with heat-labile materials, limiting their application.
    • Organic debris can reduce the effectiveness of antimicrobial agents.

    Heat and Radiation Effects

    • Application of heat can damage DNA and disrupt membrane integrity without always affecting thermal death time.
    • Radiation methods, such as gamma radiation, are effective for sterilizing heat-sensitive items like plastic Petri dishes.

    Efficacy of Disinfectants

    • The effectiveness of disinfectants can be measured by zones of inhibition, with larger zones indicating greater effectiveness.
    • Sodium benzoate is identified as a highly effective preservative against bacterial growth in food products.

    General Microbial Resistance and Preservation

    • Gram-negative bacteria are more resistant to chemical biocides than gram-positive strains.
    • Various methods, including desiccation and refrigeration, are employed for food preservation, while ionizing radiation is commonly used in industrial contexts.

    Miscellaneous

    • Some chemicals possess dual roles, serving as both disinfectants and antiseptics.
    • The pH of the medium impacts the action of disinfectants, contrary to the false belief that it has no effect.
    • Ultraviolet light can cause damage to DNA but does not create irreversible breaks.

    True/False Statements

    • Autoclaving is confirmed as the most effective method of moist heat sterilization.
    • High concentrations of salts and sugars lead to cell lysis, contrary to common belief.

    Importance of Correct Practices

    • Proper understanding of sterilization and microbial control methods is essential for preventing infections and ensuring safety in healthcare and food practices.

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    Description

    Test your knowledge with our flashcards for Microbiology Chapter 7. This quiz covers important sterilization methods and patterns of microbial death. Challenge yourself and enhance your understanding of key microbiology concepts.

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