required practicals

• What is required to view a specimen under a light microscope?

  A microscope slide
• What is a microscope slide made of?

  Clear glass or plastic
• What are the steps to prepare a slide for viewing onion cells?

  1. Add a drop of water to a clean slide.
  2. Cut an onion and separate into layers.
  3. Use tweezers to pull off epidermal tissue.
  4. Place the tissue into the water on the slide.
  5. Add a drop of iodine solution.
  6. Place a cover slip on top.
• What is the purpose of iodine solution when preparing a slide?

  It is a stain to highlight objects
• What is a cover slip made of?

  Thin, transparent plastic or glass
• What are the steps to use a light microscope to view a slide?

  1. Clip the slide onto the stage.
  2. Select the lowest-powered objective lens.
  3. Use the coarse adjustment knob to move the stage up.
  4. Look down the eyepiece and adjust focus.
  5. Use the fine adjustment knob for a clear image.
  6. Swap to a higher-powered lens if needed.
• What should you do first when using a light microscope?

  Clip the slide onto the stage
• Why do you use the coarse adjustment knob first?

  To move the stage closer to the lens
• What happens if you need greater magnification while viewing a slide?

  Swap to a higher-powered objective lens
• How can you observe the effect of sugar solution on plant tissue?

  1. Cut a potato into identical cylinders.
  2. Fill beakers with different sugar solutions.
  3. Measure the mass of the cylinders.
  4. Leave them in solutions for 24 hours.
  5. Dry and measure their masses again.
• What indicates that potato cylinders have drawn in water by osmosis?

  They will have increased in mass
• What happens to the mass of potato cylinders if water is drawn out?

  The mass will have decreased
• What is the first step in observing the effect of sugar solution on plant tissue?

  Cut up a potato into identical cylinders
• How does osmosis affect the mass of potato cylinders in different sugar solutions?

  Mass increases in dilute solutions, decreases in concentrated