Microbiology History and Techniques
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Questions and Answers

What term was used by Van Leeuwenhoek to describe microbes?

  • Animalcules (correct)
  • Microorganisms
  • Archaea
  • Bacteria

    • What is the term for the measure of how greatly a substance slows light?

  • Magnification
  • Refractive index (correct)
  • Resolution
  • Focal length

    • What is the purpose of oil in light microscopy?

  • To fix the bacteria to the slide
  • To decrease the magnification
  • To increase the focal length
  • To get better resolution and achieve 1000x magnification (correct)

    • What is the process of preparing bacteria for observation by attaching them to a slide?

    <p>Heat fixing</p> Signup and view all the answers

    What is the term for the distance between the center of the lens and the focal point?

    <p>Focal length</p> Signup and view all the answers

    Why is gram staining necessary for observing bacteria?

    <p>Because bacteria have no color</p> Signup and view all the answers

    What is the result of light moving into a different medium?

    <p>It gets detracted</p> Signup and view all the answers

    What is the purpose of the objective lens in a compound microscope?

    <p>To bend the light</p> Signup and view all the answers

    What is the significance of Louis Pasteur's work in relation to spontaneous generation?

    <p>He disproved that spontaneous generation occurs</p> Signup and view all the answers

    What is the purpose of chemical fixation in preparing bacterial samples for microscopy?

    <p>To preserve the structure of the cell</p> Signup and view all the answers

    Why do some bacteria, such as those that cause tuberculosis, require special staining procedures?

    <p>Because they have high lipid content in their cell walls</p> Signup and view all the answers

    What is the purpose of the iodine step in the Gram staining procedure?

    <p>To bind to the peptidoglycan layer</p> Signup and view all the answers

    What type of microscopy is used to visualize live bacteria without staining?

    <p>Phase-contrast microscopy</p> Signup and view all the answers

    What is the purpose of the filters in fluorescence microscopy?

    <p>To remove long wavelengths</p> Signup and view all the answers

    What is the advantage of using confocal microscopy?

    <p>It provides a three-dimensional image</p> Signup and view all the answers

    Why is it necessary to dehydrate and fix samples for transmission electron microscopy (TEM)?

    <p>To allow for the beam of electrons to pass through</p> Signup and view all the answers

    What is the difference between TEM and scanning electron microscopy (SEM)?

    <p>TEM is used for studying internal structures, while SEM is used for studying surface structures</p> Signup and view all the answers

    What is the advantage of cryotomography over other types of microscopy?

    <p>It does not require fixation or dehydration</p> Signup and view all the answers

    What is the primary reason why bacteria need to be stained for observation under a light microscope?

    <p>Because they have no color</p> Signup and view all the answers

    What is the purpose of the objective lens in a compound microscope?

    <p>To focus the light on the sample</p> Signup and view all the answers

    What is the result of using a shorter focal length in a microscope?

    <p>Greater magnification</p> Signup and view all the answers

    Why is oil needed for high-magnification microscopy?

    <p>To achieve a resolution of 1000x magnification</p> Signup and view all the answers

    What is the significance of Louis Pasteur's work?

    <p>He disproved the theory of spontaneous generation</p> Signup and view all the answers

    What is the term used to describe the measure of how greatly a substance slows light?

    <p>Refractive index</p> Signup and view all the answers

    What is the purpose of heat fixing bacteria to a slide?

    <p>To attach the bacteria to the slide</p> Signup and view all the answers

    What is the term used to describe the bending of light as it passes through a different medium?

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

    What is the significance of Van Leeuwenhoek's work?

    <p>He was the first to describe microbes</p> Signup and view all the answers

    What is the primary reason for using acid to treat certain bacteria before Gram staining?

    <p>To break down the high lipid content in the cell wall</p> Signup and view all the answers

    What is the main difference between basic and acidic dyes in bacterial staining?

    <p>Basic dyes have a positive charge and acidic dyes have a negative charge</p> Signup and view all the answers

    What is the purpose of the heat fixation step in Gram staining?

    <p>To adhere the bacteria to the slide</p> Signup and view all the answers

    What is the main advantage of using fluorescence microscopy for bacterial observation?

    <p>It enables the visualization of specific structures or molecules within the bacteria</p> Signup and view all the answers

    What is the main difference between TEM and SEM?

    <p>TEM is used for observing the internal structure of bacteria, while SEM is used for observing the surface of bacteria</p> Signup and view all the answers

    What is the purpose of the counterstain step in Gram staining?

    <p>To enhance the differentiation of Gram-positive and Gram-negative bacteria</p> Signup and view all the answers

    Why are some bacteria resistant to heat fixation?

    <p>Because they have endospores</p> Signup and view all the answers

    What is the primary advantage of using confocal microscopy for bacterial observation?

    <p>It enables the visualization of three-dimensional structures within the bacteria</p> Signup and view all the answers

    What is the main advantage of using cryotomography for bacterial observation?

    <p>It enables the visualization of internal structures without the need for fixation</p> Signup and view all the answers

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