RP6

• Microscopy


  Used to increase magnification and resolution of an object
• Types of microscopes


  • Optical
  • Electron
  • Transmission
  • Scanning
• Magnification


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


  • Plant stem
  • Acidified phloroglucinol in ethanol
  • Optical microscope
  • Microscope slides and coverslips
  • Scalpel
  • Razor blade
  • Paintbrush
  • White tile
  • Watch glass
  • Pipette
  • Wax crayon
• Calibrating 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
• Cutting transverse sections of the plant stem

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

  2. Select the thinnest sections
• Preparing the slide


  1. Place one section on a microscope slide

  2. Draw a line in wax crayon from top to bottom of the slide either side of the specimen to prevent the dye from spreading

  3. Add a few drops of concentrated phloroglucinol

  4. Lower the cover slip down carefully onto the slide

  5. Make sure there are no air bubbles in the slide which may distort the image
• Observing the slide under the microscope

  1. Place under a microscope and 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)
• Observing and measuring the stem

  1. Observe and draw the stem

  2. 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


  • Acidified phloroglucinol (corrosive and highly flammable)
  • Razor (cuts from sharp object)
  • Broken glass (cuts from sharp object)
  • Ethanol (irritant/flammable)
• Safety precautions


  • Wear eye protection; avoid contact with skin
  • Cut away from fingers; use forceps to hold sample whilst cutting, keep away from edge of desk
  • Take care when handling slides and coverslips; keep glassware away from edge of desk
  • Wear eye protection; keep away from naked flames, keep away from edge of desk
• Emergency procedures


  • Wash off skin immediately; flood eye/cuts with cold water
  • Elevate cuts; apply pressure; seek medical assistance
  • Elevate cuts; apply pressure; do not remove glass from wound; seek medical assistance
  • Wash eyes and skin with cold water
• Risk level for all hazards is low