microscopy

    Cards (43)

    • What is the purpose of microscopy in biology?
      To observe and investigate different types of cell and cell structure in eukaryotic organisms
    • What is an electron micrograph?
      A photograph of an image seen using an electron microscope
    • What is magnification?

      The number of times larger an image appears compared with the size of the object
    • What are organelles?
      Small structures within cells, each of which has a specific function
    • What is a photomicrograph?

      A photograph of an image seen using an optical microscope
    • How does resolution affect the clarity of an image?
      The higher the resolution, the clearer the image
    • What is the maximum magnification of optical microscopes?
      Up to x1500, or in some types x2000
    • Why can't optical microscopes magnify structures closer than 200 nm?

      Because their resolution limit is 0.2 μm
    • What is the wavelength range of visible light?
      Between 400 and 700 nm
    • Why can't ribosomes be examined using a light microscope?
      Because they are very small, non-membrane-bound organelles of about 20 nm diameter
    • What is the first step in using a light microscope?
      Place the specimen on the stage and clip it into place
    • What should you adjust while viewing the image for optimum light?
      The iris diaphragm
    • What is the total magnification formula for a microscope?
      Total magnification = magnifying power of the objective lens x magnifying power of the eyepiece lens
    • What is the role of stains in microscopy?
      Stains are coloured chemicals that bind to molecules in or on the specimen, making it easier to see
    • What is methylene blue used for?
      It is an all-purpose stain
    • What does acetic orcein stain?
      It binds to DNA and stains chromosomes dark red
    • What does eosin stain?

      It stains cytoplasm
    • What does Sudan red stain?
      It stains lipids
    • How do you convert a measurement in mm to μm?

      By multiplying the measurement by 1000
    • What are the advantages of optical microscopes?
      • Relatively cheap
      • Easy to use
      • Portable and usable in the field
      • Can study whole living specimens
    • What are the characteristics of laser scanning microscopes?
      • Use laser light to scan objects point by point
      • Assemble images by computer
      • Produce high-resolution images with high contrast
      • Can focus on structures at different depths
    • What are the characteristics of transmission electron microscopes?
      • Produce a 2D black-and-white image
      • Can magnify up to 2 million times
      • Used in medical professions for diagnosis
      • Require specimens to be dead and chemically fixed
    • What are the characteristics of scanning electron microscopes?
      • Produce a 3D image
      • Magnification from x15 up to x200,000
      • Specimens must be placed in a vacuum and often coated with metal
      • Use secondary electrons to create images
    • What are the limitations of electron microscopes?
      • Large and very expensive
      • Require skill and training to use
      • Specimens must be dead
      • Potential hazards from metallic salt stains
    • What is the significance of the logarithmic scale in microscopy?
      • It shows sizes of objects in steps, where each step is a 10-fold increase
    • What is the process of making microscope slides?
      • Use a special instrument to make thin slices (sections)
      • Stain and mount sections in a special chemical to preserve them
    • How can unstained specimens be observed under a microscope?
      • By using light interference or a dark background
      • Adjusting the iris diaphragm to reduce illumination
    • What is the purpose of adjusting the iris diaphragm on a light microscope?
      To reduce the illumination of the specimen
    • What is the process of staining specimens in microscopy?
      • Making very thin slices called sections
      • Staining and mounting them in a special chemical to preserve them
    • What is the function of stains in microscopy?
      Stains are coloured chemicals that bind to molecules in or on the specimen
    • What is differential staining?

      It is a technique where specific stains bind to specific cell structures, staining them differently
    • What are the steps to calculate the actual thickness of a leaf using a photomicrograph?
      1. Measure the widest part of the leaf in mm
      2. Convert that measurement to μm by multiplying by 1000
      3. Divide this figure by the magnification
    • What are the key features of prepared microscope slides?
      • Made by dehydrating specimens
      • Embedded in wax to prevent distortion during slicing
      • Permanently fixed for observation
    • What is an eyepiece graticule?

      • A measuring device placed in the eyepiece of a microscope
      • Acts as a ruler when viewing an object under the microscope
    • What is a stage graticule?

      • A precise measuring device placed on the microscope stage
      • Used to calibrate the value of eyepiece divisions at different magnifications
    • How do you use an eyepiece graticule and a stage graticule together?
      1. Insert an eyepiece graticule into the eyepiece
      2. Place a stage graticule on the microscope stage and bring it into focus
      3. Align both graticules to check the value of one eyepiece division
    • What is the length of each division on a stage graticule?
      Each division is 0.01 mm or 10 μm
    • How do you measure the actual width of a root using a graticule?

      Measure the length of the line in small divisions and multiply by 10 μm
    • If the total magnification is x100 and the eyepiece magnification is x10, what is the magnification of the objective lens?
      The objective lens magnification is x10
    • What is the equation for calculating actual size from magnification?
      • Actual size = Image size / Magnification
      • Magnification = Image size / Actual size
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