investigating cells

• Light microscopes

  • Uses light and lenses to magnify specimens, allowing us to see individual cells and large subcellular structures like nuclei
• Electron microscopes

  • Uses electrons to form an image and can magnify much more than light microscopes, showing us the finer details of cell structures like mitochondria and chloroplasts
• Using a light microscope

  Secure slide on stage, start with lowest-powered objective lens, adjust coarse then fine focus, switch to higher-powered lens to see more detail
• Labelling a microscope

  A) eyepiece lens

  B) coarse adjustment knob

  C) objective lenses

  D) fine adjustment knob

  E) stage

  F) light

  
• Magnification = image size / actual size
• Slide Preparation

  1. Place a tissue sample on a microscope slide.
  2. add a few drops of a suitable stain.
  3. lower a coverslip onto the tissue.
  4. place the slide on the microscope stage and focus on the cells using low power.
  5. change to high power and refocus
  6. draw any types of cells that can be seen
  7. add a scale line to the diagram
• Using a Light Microscope

  • Secure the slide on the stage of the microscope.
  • Begin with the LOWEST-POWERED OBJECTIVE LENS.
  • Adjust the COARSE ADJUSTMENT KNOB to bring the stage close to the lens without touching.
  • Look through the EYEPIECE and use the COARSE ADJUSTMENT KNOB to find the focus.
  • adjust the focus with the FINE ADJUSTMENT KNOB for a clear image.
  • For greater detail, switch to a higher-powered objective lens and refocus.
• Drawing Observations

  • Draw what you observe with a PENCIL.
  • Ensure the drawing occupies at least half of the space provided.
  • Use clear, UNBROKEN LINES; avoid coloring or shading.
  • Draw cells proportionally, labelling important features like nucleus or chloroplasts with straight lines.
  • Include a TITLE and the MAGNIFICATION LEVEL

  
• 1 mm = 1000 μm
• The cells on the slides are not clear to see.

  describe how to adjust the microscope to see the cells more clearly.

  focus it
• 16

  
• it is easier to view cells using the low-power objective lens first because it's easier to focus and its the biggest field of view.

  
• to focus an image the objective lens should be moved away from the stage to avoid damage to lens.

  
• (x) 5

  
• 860 micrometres

  
• • place slide on stage
  • use lowest power
  • switch light to pass through the slide
  • move stage as close to lens as possible
  • slide must not touch lens
  • turn focussing knob so slide moves away from lens
  • turn focussing knob until image comes into focus
  • use fine focus to get clear image
  • change objective lens to x10
  • x5 eyepiece and x10 objective lenses
  • refocus slide using focussing knob

  
• describe how the student should adjust the microscope to see the cells on slide B more clearly.

  change the lens to a high power.