Microorganism Quantification Methods Quiz
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Questions and Answers

How many microscope fields are typically counted in the Petroff-Hausser slide method?

  • 5
  • 12
  • 8
  • 10 (correct)
  • What is the main disadvantage of using the Petroff-Hausser slide for direct microscopic counting?

  • The slide does not provide accurate measurements of microorganisms.
  • It cannot distinguish between living and dead cells during counting. (correct)
  • The counting area is too small for accurate counting.
  • The slide requires complex staining techniques.
  • In the Breed method, bacteria are counted in at least how many different areas under the microscope?

  • 8
  • 5
  • 10 (correct)
  • 12
  • What is the basis for counting in the Thoma slide method?

    <p>Counting in a volume of 0.1 mm3</p> Signup and view all the answers

    What is the final result obtained by the counting method with the Thoma slide?

    <p>Number of microorganisms per milliliter</p> Signup and view all the answers

    Which method is most suitable for determining the amount of long filament bacteria?

    <p>Chemical measurement of cell mass</p> Signup and view all the answers

    Why are direct microscopic counting methods not suitable for samples containing low concentrations of microorganisms?

    <p>Inability to distinguish between live and dead microorganisms</p> Signup and view all the answers

    What is the disadvantage of direct microscopic counting methods?

    <p>Inability to distinguish between live and dead microorganisms</p> Signup and view all the answers

    What must be done prior to counting motile cells using direct microscopic counting methods?

    <p>Cell immobilization</p> Signup and view all the answers

    Which method is suitable for determining the amount of single-celled organisms such as bacteria and yeasts?

    <p>Total cell count</p> Signup and view all the answers

    What is the main disadvantage of direct microscopic counting methods for determining the total cell number?

    <p>Inability to distinguish between live and dead microorganisms</p> Signup and view all the answers

    Which method is most suitable for determining the amount of long filament bacteria?

    <p>Measurement of dry weight of cells</p> Signup and view all the answers

    What must be done prior to counting motile cells using direct microscopic counting methods?

    <p>Add a chemical fixative to immobilize the cells</p> Signup and view all the answers

    In the Breed method, bacteria are counted in at least how many different areas under the microscope?

    <p>6 different areas</p> Signup and view all the answers

    Why are direct microscopic counting methods not suitable for samples containing low concentrations of microorganisms?

    <p>They may not accurately distinguish between live and dead microorganisms</p> Signup and view all the answers

    What is the main disadvantage of using the Breed method for direct microscopic counting?

    <p>Inability to measure all dead or live cells accurately</p> Signup and view all the answers

    In the Thoma slide method, the counting area is divided into how many large squares?

    <p>16 large squares</p> Signup and view all the answers

    What is the basis for counting in the Petroff-Hausser slide method?

    <p>Dividing the middle part of the well area by lines</p> Signup and view all the answers

    What is the advantage of using the Thoma slide method for counting blood, sperm, and yeast?

    <p>Counting in a volume of 0.1 mm3</p> Signup and view all the answers

    Why are direct microscopic counting methods not as accurate as culture methods in measuring all dead or live cells?

    <p>Difficulty in distinguishing between live and dead cells</p> Signup and view all the answers

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