cpac 2

• Microscopy


  Used to increase magnification and resolution of an object
• Optical microscopes and electron microscopes

  • Electron microscopes can be transmission or scanning
• Magnification


  Calculated by dividing the size of the image by the size of the actual object
• Equipment


  • Plant stem
  • Optical microscope
  • Eyepiece graticule
  • Stage micrometer
  • Toluidine Blue O stain
  • Microscope slides and coverslips
  • Razor blade
  • Paintbrush
  • White tile
  • Watch glass
  • Pipette
  • Mounted needle
  • Lens tissue
  • Paper towels
• Calibrate the eyepiece graticule


  Place both on the stage and line up the divisions of the stage micrometer (which have a known length) with the divisions of the eyepiece graticule (for which the length is unknown) to calculate the length of one division of the graticule
• Cut transverse sections of plant stem

  1. On the white tile using a razor, wet to reduce friction

  2. Select the two thinnest sections
• Mount one section in water on a microscope slide

  1. Lower the cover slip down carefully onto the slide

  2. Make sure there are no air bubbles in the slide which may distort the image
• Add toliuidine blue O stain to the other section

  1. Leave for three minutes

  2. Mount in water on another microscope slide and add the cover slip
• Place under a microscope

  1. Set the objective lens on the lowest magnification

  2. Use the coarse adjustment knob to move the lens down to just above the slide

  3. Use the fine adjustment knob to carefully re-adjust the focus until the image is clear (can use a higher magnification if needed)
• Observe and draw the stem

  Measure the size of the stem diameter and vascular bundle using the calibrated eyepiece graticule
• Tips for Biological Drawings

  • Use an HB pencil and a white, unlined sheet of paper
  • Draw in the centre of the page, and have the drawing take up at least half of the paper
  • Label the diagram, also in pencil
  • Use a ruler for straight lines and for labelling
  • Use clear lines - don't smudge or feather them
  • Only draw what you can see
  • Do an outline first
  • Do not use shading or colour
  • Write the lens power that has been used somewhere on the diagram
• Hazards


  • Toluidine blue O stain
  • Razor/scalpel
  • Broken glass
• Toluidine blue O stain


  May cause harm/irritation to eyes or in cuts
• Safety Precautions for Toluidine blue O stain

  • Keep away from a naked flame; wear eye protection; avoid contact with skin
• Emergency for Toluidine blue O stain

  Put out fire, seek assistance; wash off skin immediately; flood eye/cuts with cold water
• Razor/scalpel


  Cuts from sharp object
• Safety Precautions for Razor/scalpel


  • Cut away from fingers; use forceps to hold sample whilst cutting; keep away from edge of desk
• Emergency for Razor/scalpel


  Elevate cuts; apply pressure; seek medical assistance
• Broken glass


  Cuts from sharp object
• Safety Precautions for Broken glass

  • Take care when handling slides and coverslips; keep glassware away from edge of desk
• Emergency for Broken glass


  Elevate cuts; apply pressure; do not remove glass from wound; seek medical assistance