Microscopy

• Why are microscopes important for biology?


  They allow us to see things that are not visible to the naked eye.
• What are the main types of microscopes and their functions?


  • Light microscopes: Use light and lenses to magnify specimens, allowing us to see individual cells and large subcellular structures.
  • Electron microscopes: Use electrons for higher magnification and resolution, enabling us to see smaller details like ribosomes and plasmids.
• What is the difference between light microscopes and electron microscopes?


  Light microscopes use light, while electron microscopes use electrons for imaging.
• What does resolution refer to in microscopy?


  Resolution is the ability to distinguish between two points.
• Why do electron microscopes provide a sharper image than light microscopes?


  Because they have a higher resolution.
• What is the formula for calculating magnification?


  Magnification = image size / real size
• If a specimen is 50 µm wide and viewed under a magnification of x 100, what is the width of the image?


  The width of the image is 5000 µm or 5 mm.
• How do you convert micrometres to millimetres?


  By dividing by 1000.
• What are the steps to prepare a slide for viewing under a light microscope?


  1. Add a drop of water to the slide.
  2. Cut and separate onion layers.
  3. Peel off epidermal tissue and place it in water.
  4. Add a drop of iodine solution as a stain.
  5. Place a cover slip over the specimen.
• What is the purpose of using a stain like iodine solution on a specimen?


  To highlight objects in a cell by adding color.
• What are the main parts of a light microscope that you need to know?

  • Eyepiece
  • Coarse adjustment knob
  • Fine adjustment knob
  • High and low power objective lenses
  • Stage
  • Light
• What are the steps to use a light microscope to look at 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 are the guidelines for drawing observations made under a microscope?


  • Use a sharp pencil.
  • Draw clearly without coloring or shading.
  • Ensure the drawing is proportional.
  • Include a title and magnification.
  • Label important features with straight lines.
• How do you calculate the magnification of a drawing?

  Magnification = length of drawing / real length of object
• If the real length of an onion cell is 0.3 mm and the length of the drawing is 30 mm, what is the magnification?


  The magnification is x 100.
• How might the appearance of light microscopes vary?


  • They may have different numbers of eyepieces.
  • They should still have the same basic features.