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Microbiology: Bacterial Growth and Physiology

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이 집합의 용어 (40)

  • Why does bacterial growth decrease above the maximum growth temperature?
    Enzymes and proteins become denatured, impairing cellular functions.
  • Which bacterial growth phase shows decreasing viable cell numbers due to nutrient exhaustion and waste accumulation?
    The death phase.
  • Do all microorganisms in biofilms belong to the same species?
    No, biofilms often contain multiple species and organisms from different kingdoms.
  • What environment favors growth of a bacterium that grows best at pH 9.5?
    An alkaline lake.
  • What is the effect of a drug that prevents FtsZ ring formation in bacteria?
    Cytokinesis cannot occur, preventing cell division.
  • A microorganism requiring at least 9% NaCl for growth is classified as a:
    Extreme halophile.
  • Which bacterial growth phase is metabolically active but shows no increase in cell number?
    The stationary phase.
  • What component primarily holds a biofilm together?
    The EPS (extracellular polymeric substance) matrix.
  • How can growth of a foodborne pathogen be reduced without antimicrobials?
    By reducing water availability and lowering temperature.
  • Why are jams and jellies resistant to microbial spoilage?
    High sugar content reduces water availability.
  • What does continued bacterial growth despite oxygen depletion indicate?
    The organism may be capable of anaerobic metabolism.
  • Which bacterial growth phase occurs when a culture reaches carrying capacity?
    The stationary phase.
  • Why is infection by a hyperthermophile unlikely in the human body?
    Its enzymes are optimized for much higher temperatures than human body temperature.
  • How is a bacterium growing best at pH 2.5 classified?
    As an acidophile.
  • During which bacterial growth phase do patients often first develop symptoms?
    During the log (exponential) phase.
  • A bacterium growing only at the top of a thioglycolate tube is classified as:
    An obligate aerobe.
  • Which group likely causes growth of pathogens in refrigerated foods at 4°C?
    Psychrotrophs.
  • A bacterium growing evenly throughout a thioglycolate tube without using oxygen is:
    An aerotolerant anaerobe.
  • What characteristic contributes most to biofilm resistance?
    The protective EPS matrix.
  • What process occurs when a bacterium placed in concentrated brine immediately loses water?
    Plasmolysis.
  • Why are obligate anaerobes often harmed by oxygen?
    They lack enzymes that detoxify reactive oxygen species.
  • A microorganism growing optimally at 4°C and not above 20°C is a:
    Psychrophile.
  • What explains recurrent catheter-associated infections?
    Development of biofilms on the catheter surface.
  • A bacterium growing at 4°C, 25°C, and 37°C is likely a:
    Psychrotroph, capable of growth during refrigeration.
  • Successful antibiotic treatment should push bacteria into which phase?
    The death phase.
  • A chronic infection with persistent low-level symptoms resembles which bacterial phase?
    The stationary phase.
  • Which process is affected if a mutant bacterium lacks functional Par proteins?
    Chromosome segregation.
  • What effect does a drug interfering with quorum sensing have?
    It causes reduced community coordination and virulence.
  • If a bacterial species doubles every 30 minutes, how many cells after 2 hours starting from 1,000?
    16,000 cells.
  • Most effective strategy to prevent biofilm formation on medical implants?
    Prevent initial bacterial attachment.
  • A pathogen synthesizing enzymes but not increasing in number is in which phase?
    The lag phase.
  • During which phase are secondary metabolites like antibiotics commonly produced?
    The stationary phase.
  • Why can strict anaerobes survive within dental plaque?
    Surface organisms consume oxygen, creating anaerobic niches.
  • Why do generation times vary between bacterial species?
    Generation time varies among species and environmental conditions.
  • A bacterial community attached to a surface with EPS and quorum sensing is a:
    Biofilm.
  • An organism growing with oxygen but switching to anaerobic respiration is a:
    Facultative anaerobe.
  • Why are most human pathogens neutrophiles?
    Because human body fluids are near neutral pH.
  • How does Helicobacter pylori survive stomach acidity?
    It produces urease that raises local pH.
  • A drug inhibiting Fts proteins affects:
    Cell division.
  • During which phase are bacteria most susceptible to antibiotics?
    During the log (exponential) phase.