Required practical - using a light microscope

• Aim of the experiment

  • to use a light microscope to examine animal and plant cells
  • to make observations and draw scale diagrams of cells
• Method

  1. rotate objective lenses so the low power is in line with stage
  2. turn coarse focus so the stage is as close to the objective lens as possible. Don't look through microscope to do this
  3. place microscope slide on stage. Line it up so the specimen is in centre of the stage, where the light passes through
  4. focus the slide towards you by turning the coarse focus adjustment
  5. draw a low power image or record a digital image of what you see. The, rotate the objectives so that the high power objective is in line with the stage
  6. bring the slide back into focus using the fine focus adjustment.
• Risks

  • care must be taken when looking down the microscope if the illumination is too bright
  • care must be taken when using microscope stains
  • care must be taken when handling coverslips and microscope slides
• A low power diagram is used:

  • as a plan to show the arrangement of any distinct regions of the tissue, for example the tissues in a plant root
  • to show the outline of individual cells that make up the tissue, if the tissue is uniform
• A high power diagram is used:

  • a detailed image of a part of the slide
  • to show a single cell, eg of a single cheek cell or onion cell