Practicals

• What is the aim of the investigation described in the study material?

  To investigate biological specimens using microscopes
• What equipment is needed for the investigation of cells using microscopes?

  • Light microscope
  • Microscope slide
  • Cover slip
  • Onion
  • Forceps
  • Iodine solution
  • White tile
  • Scalpel
  • Any other prepared plant and animal cell slides
• What is the first step in the method for preparing an onion slide?

  Peel off an epidermal layer on the onion using forceps
• How should the onion tissue be mounted on the microscope slide?

  With a drop of water using a pipette, ensuring it lies flat
• Why is iodine solution added to the onion cells?

  To stain the cells so that internal structures become visible
• How should the cover slip be placed on the slide?

  By placing one edge down first and slowly lowering the other side
• What should be done to remove excess stain from the slide?

  Soak it with paper towels
• What is the next step after placing the slide on the stage of the microscope?

  Turn the nosepiece to select a low power objective
• What should you do before looking into the eyepiece of the microscope?

  Use the coarse adjustment knob to raise the stage until the cover slip just touches the objective
• What is the purpose of turning the coarse adjustment knob after looking into the eyepiece?

  To move the stage away until the image comes into focus
• What should you do after selecting a high power objective?

  Repeat the focusing process using the fine adjustment knob
• What should be included in the labelled drawing of the cells?

  Features such as cell wall and nucleus
• What should you write down after making a labelled drawing of the cells?

  The magnification used
• What should you do after completing the steps with the onion slide?

  Repeat the steps using a prepared slide
• What safety precautions should be taken during the experiment?

  • Wear safety goggles when handling iodine solution
  • Be careful with broken glass if a slide breaks