Microbial Growth and Carrying Capacity
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Questions and Answers

What is the primary mechanism of action of certain microbial control agents on the plasma membrane?

  • Facilitating the formation of hydrogen bonds
  • Altering its permeability due to damage to lipid and protein components (correct)
  • Forming covalent bonds with proteins
  • Increasing the membrane potential

    • What is the main difference between antimicrobial and antibacterial compounds?

  • Antimicrobial compounds are less effective against fungi
  • Antimicrobial compounds are more effective against viruses
  • Antimicrobial compounds are only effective against endospores
  • Antimicrobial compounds are effective against all types of microorganisms, while antibacterial compounds are only effective against bacteria (correct)

    • What is the purpose of commercial sterilization in canned food?

  • To kill vegetative pathogens
  • To promote the growth of beneficial microorganisms
  • To kill endospores of Clostridium botulinum (correct)
  • To remove prions from the food

    • What is the effect of Triclosan on microbial populations?

    <p>It gives rise to antimicrobial resistance indirectly</p> Signup and view all the answers

    What is the primary goal of degerming?

    <p>To remove microbes from a limited area, such as the skin around an injection site</p> Signup and view all the answers

    What is the effect of certain microbial control agents on cellular proteins?

    <p>They damage cellular proteins by breaking hydrogen bonds and covalent bonds</p> Signup and view all the answers

    What is the primary mechanism by which moist heat kills microorganisms?

    <p>Denaturation of enzymes</p> Signup and view all the answers

    What is the term used to describe the lowest temperature at which all microorganisms in a liquid culture are killed in 10 minutes?

    <p>Thermal death point</p> Signup and view all the answers

    What is the primary advantage of autoclaving over boiling for sterilization?

    <p>It is more effective against bacterial spores</p> Signup and view all the answers

    What is the purpose of the HTST method of pasteurization?

    <p>To destroy pathogens without altering the flavor of the food</p> Signup and view all the answers

    What is the term used to describe the absence of significant contamination?

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

    What is the term used to describe the length of time required to kill all bacteria in a liquid culture at a given temperature?

    <p>Thermal death time</p> Signup and view all the answers

    What is the primary effect of ionizing radiation on water?

    <p>Formation of highly reactive hydroxyl radicals</p> Signup and view all the answers

    What is the wavelength of UV radiation that is most effective for germicidal purposes?

    <p>260 nm</p> Signup and view all the answers

    How do microwaves kill microbes?

    <p>Indirectly, as materials get hot</p> Signup and view all the answers

    What is the effect of refrigeration on microbial growth?

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

    What is the purpose of lyophilization?

    <p>To preserve microbial cultures, food, and drugs</p> Signup and view all the answers

    What is the characteristic of chlorine as a disinfectant?

    <p>Effective against all the test bacteria but more effective against gram-positive</p> Signup and view all the answers

    What is the primary factor that limits the growth of bacteria in an environment?

    <p>Available nutrients</p> Signup and view all the answers

    During which phase of the microbial growth curve do bacteria prepare for binary fission?

    <p>Lag phase</p> Signup and view all the answers

    What is the result when the number of bacterial cells produced is equal to the number of cells that die?

    <p>Stationary phase</p> Signup and view all the answers

    What is the purpose of adding 20% glycerol to an agar slant?

    <p>To preserve the bacteria for up to 6 years</p> Signup and view all the answers

    What is the definition of generation time in microbiology?

    <p>The time it takes for a bacterial cell to divide or double in number</p> Signup and view all the answers

    What is the relationship between the number of bacterial cells produced and the number of cells that die when a population exceeds the carrying capacity?

    <p>The number of cells produced is equal to the number of cells that die</p> Signup and view all the answers

    Which of the following factors should be considered when selecting a disinfectant?

    <p>Presence of organic matter and temperature</p> Signup and view all the answers

    What is the primary purpose of the use-dilution test?

    <p>To evaluate the bacterial survival in a manufacturer's recommended dilution</p> Signup and view all the answers

    Which of the following acids is used as a food preservative to inhibit fungal metabolism?

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

    What is the mechanism of action of aldehydes, such as formaldehyde and glutaraldehyde, as chemical disinfectants?

    <p>Denaturation of proteins</p> Signup and view all the answers

    What is the primary mechanism of action of ethylene oxide as a sterilizing agent?

    <p>Protein denaturation</p> Signup and view all the answers

    Which of the following methods is used to evaluate the effectiveness of agents against viruses, endospore-forming bacteria, mycobacteria, and fungi?

    <p>Use-dilution test</p> Signup and view all the answers

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