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Questions and Answers

What is the main function of the nosepiece in a microscope?

  • Hold the slide in place
  • Concentrate light onto the specimen
  • Rotate the objective lenses (correct)
  • Control the amount of light passing through

    • Which part of the microscope is responsible for supporting the head of the microscope?

  • Arm (correct)
  • Objective Lens
  • Fine Adjustment Knob
  • Stage Clips

    • What is the purpose of the diaphragm in a light microscope?

  • Hold the slide in place
  • Rotate between different magnifications
  • Move the stage up and down quickly
  • Control the amount of light going through the condenser (correct)

    • Which microscope uses two or more lenses for magnification?

    <p>Compound Light Microscope</p> Signup and view all the answers

    What is the function of the condenser in a microscope?

    <p>Concentrate light onto the specimen</p> Signup and view all the answers

    Which part of the microscope is used for precise focusing?

    <p>Fine Adjustment Knob</p> Signup and view all the answers

    What is the main purpose of drawing a standard curve in an ELISA experiment?

    <p>To plot the concentration on the X-axis and absorbance on the Y-axis</p> Signup and view all the answers

    What is the role of the quality control sample in an ELISA experiment?

    <p>It helps determine if the results are within an acceptable range</p> Signup and view all the answers

    Who pioneered the technique of electrophoresis for protein separation?

    <p>Arne Tiselius</p> Signup and view all the answers

    What is the definition of electrophoresis?

    <p>&quot;Migration of charged molecules under an external magnetic field&quot;</p> Signup and view all the answers

    In an ELISA experiment, what happens after reading the results?

    <p>The standard curve is drawn</p> Signup and view all the answers

    How is the unknown concentration of samples determined in an ELISA experiment?

    <p>By finding the concentration opposite to the absorbance on the standard curve</p> Signup and view all the answers

    What are the most common microorganisms found on the skin surface?

    <p>Staphylococcus epidermidis and Diphtheroids</p> Signup and view all the answers

    What is the main role of normal flora on the skin surface in preventing infections?

    <p>Competing with pathogenic organisms for resources</p> Signup and view all the answers

    Which bacteria protect the conjunctiva from infections?

    <p>Moraxella and Diphtheroids</p> Signup and view all the answers

    What is the main protective mechanism of lysozyme in tears for the eyes?

    <p>Breaking down bacterial cell walls</p> Signup and view all the answers

    Under what conditions can resident Bacteroides species become pathogenic in the peritoneal cavity or pelvic tissues?

    <p>When introduced into these tissues due to trauma</p> Signup and view all the answers

    What distinguishes common resident bacteria such as Bacteroides from becoming pathogenic under normal circumstances?

    <p>They maintain a commensal relationship with the host</p> Signup and view all the answers

    What is the primary purpose of Gram staining in ecological studies?

    <p>To observe microorganisms labeled by fluorochromes</p> Signup and view all the answers

    Which scientist is credited with the development of the Gram staining technique?

    <p>Hans Christian Gram</p> Signup and view all the answers

    What did Carl Weigert add to the Gram staining procedure a few years after its initial development by Hans Christian Gram?

    <p>Staining with Safranin as a counterstain</p> Signup and view all the answers

    What is a limitation of the Gram staining technique mentioned in the text?

    <p>Not all bacteria can be definitively classified by this technique</p> Signup and view all the answers

    Which type of bacteria did Hans Christian Gram discover preferentially took up and retained certain stains?

    <p>Gram-positive bacteria</p> Signup and view all the answers

    How did Carl Weigert's addition of Safranin staining enhance the Gram staining procedure?

    <p>It counterstained Gram-negative bacteria red for visualization</p> Signup and view all the answers

    What is the main purpose of agarose gel electrophoresis?

    <p>To separate molecules based on their molecular size</p> Signup and view all the answers

    In agarose gel electrophoresis, why do smaller molecules move faster compared to larger molecules?

    <p>Smaller molecules penetrate the agarose gel more easily</p> Signup and view all the answers

    How are biomolecules separated in agarose gel electrophoresis?

    <p>By their molecular size</p> Signup and view all the answers

    What is the role of the agarose gel in agarose gel electrophoresis?

    <p>To provide a medium for biomolecule separation based on size</p> Signup and view all the answers

    Which technique might benefit from using molecules separated by agarose gel electrophoresis?

    <p><strong>PCR</strong></p> Signup and view all the answers

    Why is agarose gel electrophoresis commonly used in biotechnology laboratories?

    <p>To separate nucleic acids based on size</p> Signup and view all the answers

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