Bacteria revision notes quiz
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Bacteria revision notes quiz

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Questions and Answers

Which structure allows some bacteria to withstand mechanical stress?

  • Biofilms (correct)
  • Pili
  • Endospores
  • Flagella

    • What is the correct genus name for the bacterium S. salivarius?

  • Salivarius
  • Firmicutes
  • Streptococcaceae
  • Streptococcus (correct)

    • Which of the following is associated with localized aggressive periodontitis?

  • Porphyromonas gingivalis
  • Bacteroides fragilis
  • Streptococcus salivarius
  • Aggregatibacter actinomycemcomitans (correct)

    • Which kingdom do bacteria belong to?

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

    What is the family name of Streptococcus salivarius?

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

    Which statement about species naming is correct?

    <p>Species names are typically in italics and lowercase.</p> Signup and view all the answers

    What type of bacterium is Porphyromonas gingivalis?

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

    What is the major characteristic of the division Firmicutes?

    <p>Low DNA content</p> Signup and view all the answers

    Which of the following is a type of mechanical stress that bacteria can resist?

    <p>Pressure/agitation</p> Signup and view all the answers

    Which of the following terms describes the systematic classification of organisms?

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

    What characteristic allows Gram negative bacteria to appear pink under a microscope?

    <p>Thin peptidoglycan layer</p> Signup and view all the answers

    Which factor is required for the metabolic processes of most Gram negative bacteria?

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

    Which of the following correctly describes anaerobes?

    <p>Do not need oxygen and may be harmed by it</p> Signup and view all the answers

    What significant component is characteristic of the outer layer of Gram negative bacteria?

    <p>Lipopolysaccharide layer</p> Signup and view all the answers

    In which environment are aerobes most commonly found?

    <p>Near the surface where oxygen is highest</p> Signup and view all the answers

    What type of disease is associated with Porphyromonas gingivalis?

    <p>Periodontal disease</p> Signup and view all the answers

    What type of organism requires a low oxygen environment to grow optimally?

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

    Which characteristic allows some bacteria to survive in dry conditions?

    <p>Formation of spores</p> Signup and view all the answers

    What happens to Gram negative bacteria when exposed to crystal violet stain?

    <p>They do not retain the crystal violet stain</p> Signup and view all the answers

    Which group of microorganisms prefers moderate temperatures around 30-40 degrees Celsius?

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

    Which of the following does NOT describe the environmental requirements for Gram negative bacteria?

    <p>Optimum growth in aerobic conditions</p> Signup and view all the answers

    What do capnophiles specifically require for optimal growth?

    <p>Increased carbon dioxide levels</p> Signup and view all the answers

    What structural characteristic distinguishes Gram-positive bacteria from Gram-negative bacteria?

    <p>Thick peptidoglycan cell wall</p> Signup and view all the answers

    What is a common misconception about the structure of Gram negative bacteria?

    <p>They have a thick peptidoglycan layer.</p> Signup and view all the answers

    Which microorganisms are known to thrive in high salt concentrations?

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

    Which of the following statements is true about bacteria?

    <p>They are prokaryotic microorganisms</p> Signup and view all the answers

    What is the optimal temperature for thermophiles?

    <p>60-70 degrees Celsius</p> Signup and view all the answers

    What group of microorganisms prefers acidic environments?

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

    What is the primary function of bacteria?

    <p>Metabolizing and reproducing</p> Signup and view all the answers

    Which of the following bacteria is an example of a Gram-positive organism?

    <p>Staphylococcus aureus</p> Signup and view all the answers

    Which type of light can promote bacterial growth but high-intensity visible light can kill bacteria?

    <p>Low power visible light</p> Signup and view all the answers

    How is the DNA of bacteria structured?

    <p>As circular DNA chromosomes</p> Signup and view all the answers

    Which organisms are optimal at extremely high temperatures, typically around 90-100 degrees Celsius?

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

    What kind of microorganisms can tolerate and live in neutral pH environments?

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

    Which staining method is primarily used for Gram-positive bacteria?

    <p>Crystal violet staining</p> Signup and view all the answers

    Which of the following is NOT a feature of bacteria?

    <p>Eukaryotic organization</p> Signup and view all the answers

    Which of the following classifications includes organisms that prefer high temperature environments?

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

    What typically differentiates a Gram-negative bacterium from a Gram-positive bacterium when stained?

    <p>It has thinner peptidoglycan layers.</p> Signup and view all the answers

    What is the main reason that Gram-positive bacteria retain the crystal violet stain during the Gram staining process?

    <p>Thick peptidoglycan wall</p> Signup and view all the answers

    Which of these functions are commonly associated with bacteria?

    <p>Reproduce and metabolize nutrients</p> Signup and view all the answers

    Study Notes

    Bacteria

    • Small, single-celled microorganisms.
    • Prokaryotic: lack membrane-bound organelles, have a single circular DNA chromosome.
    • Gram-positive bacteria: have a thick peptidoglycan layer in their cell wall, retain crystal violet stain (e.g., Streptococcus mutans).
    • Gram-negative bacteria: have a thin peptidoglycan layer with a thick lipopolysaccharide layer, don't retain crystal violet stain, appearing pink (e.g., Porphyromonas gingivalis).
    • Gram-negative bacteria often possess endotoxins, which can contribute to inflammation.

    Environmental Requirements for Bacteria

    • Moisture: Required for metabolic processes. Most thrive in moist environments, but some can survive in dry conditions by forming spores.
    • Oxygen:
      • Anaerobes: do not need oxygen, may even be harmed by it (e.g., Porphyromonas gingivalis).
      • Aerobes: require oxygen for survival.
      • Microaerophiles: grow optimally in lower oxygen environments but still require some.
      • Facultative anaerobes: can adapt and live within a range of different oxygen levels. (e.g., Streptococcus mutans).
    • Carbon Dioxide: Capnophiles need increased CO2 to grow, but most can grow with normal atmospheric CO2 levels.
    • Temperature:
      • Psychrophiles: cold, optimal temperature 5-15 °C.
      • Mesophiles: moderate, optimal temperature 30-40 °C.
      • Thermophiles: high, optimal temperature 60-70 °C.
      • Hyperthermophiles: extremely high, optimal temperature 90-100 °C.
    • pH:
      • Acidophiles: thrive in acidic environments.
      • Neutrophiles: thrive in neutral environments.
      • Alkaliphiles: thrive in alkaline environments.
    • Light: High intensity visible light can kill bacteria, while low power visible and near-infrared light can promote bacterial growth.
    • Osmotic effect: Halophiles grow and develop in high salt concentration areas.
    • Mechanical stress: Some bacteria can withstand pressure/agitation by forming biofilms or protective structures (spores/capsules).

    Classification of Bacteria

    • Taxonomy: Systematic classification of organisms into groups.
    • The scientific name comes from the last two ranks: Genus and species.
    • Genus name is capitalized, species name is not.
    • Scientific name is usually in italics.
    • Example: Streptococcus salivarius (Genus: Streptococcus, Species: salivarius).

    Bacteria in Dentistry

    • Periodontal disease:
      • Porphyromonas gingivalis: Gram-negative, anaerobic bacteria that contributes to inflammation and tissue destruction.
      • Aggregatibacter actinomycetemcomitans: Gram-negative, facultative anaerobe that can cause localized aggressive periodontitis.

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    Bacteria Revision PDF

    Description

    This quiz explores the fundamental features of bacteria, focusing on their classification as prokaryotic microorganisms. It covers differences between gram-positive and gram-negative bacteria, as well as their environmental requirements for growth. Test your knowledge on the characteristics and conditions necessary for bacterial survival!

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