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Biology LibreTexts

Part 3: Investigation of Pond Water & Microorganisms

  • Page ID
    16583
  • Investigation of Pond Water & Microorganisms

    Materials

    • Compound microscope

    • Microscope slide

    • Coverslip

    • Transfer pipette

    • Pond water sample

    Procedure

    1. Using the transfer pipette, transfer a drop of pond water onto a microscope slide. The best specimens usually come from the bottom and probably will contain chunks of algae or other debris that you can see with your naked eye.

    2. Place coverslip onto the slide.

    3. Use the SCANNING (4x) objective to focus, then move the mechanical stage around to scan the slide for live microorganisms. You are looking for tiny swimming beings- they may look green or clear and might be very small. Choose one to focus on and center it in your visual field.

      You may wish to use the ProtoSlo to keep your organisms from swimming to quickly!

    4. Switch to low power (10x). This may be sufficient to view your chosen organism. Try to note how it moves and do your best to draw it as you see it, unless you need more magnification.

    5. Once you have centered and focused the image, switch to high power (40x) and refocus. Note movements and draw the organism as you see it.

      Remember, do NOT use the coarse adjustment knob at this point!

    Screen Shot 2019-01-01 at 10.47.17 PM.png

    Questions:

    1. Why is it important to begin focusing with the scanning objective?

     

    2. If you’re using the 40x objective and you know your ocular is 10x, what is the total magnification?

     

    3. If you bump your microscope and lose focus, what do you do to refocus your specimen?

     

    4. Why must you center your image before switching to a higher objective?