onion cell slide practical

• How To Use A Light Microscope

  1. Plug in the microscope and turn on the light

  2. Place your prepared onion slide on the stage, ensuring the specimen is in the centre and secure with the clips

  3. Turn the objective lens to its lowest magnification

  4. Turn the coarse adjustment knob until the objective lens is almost touching the microscope slide

  5. Looking through the eyepiece and using the coarse adjustment knob, turn it until the cells are in focus

  6. Use the fine adjustment knob to bring the cells into clear focus

  7. Repeat this process, switching to a higher power (x100 and x400 magnification)
• How To Prepare A Microscope Slide for an Onion

  1. Using the pipette, add a drop of water to the microscope slide.
  2. Carefully peel off a thin piece of epidermal tissue from the inside of the onion.
  3. Place this tissue on the microscope slide, ensuring it is as flat as possible.
  4. Add a drop of iodine to the onion tissue.
  5. Carefully, using the pointed needle (as shown below), lower the cover slip onto the slide ensuring there are no air bubbles.
  6. Use the blotting paper to absorb any excess water or iodine solution.