6.3: Lab Report
Microscopy Exercise
A. Brightfield Microscopy - Prepared Slides
1. Amoeba proteus
Each mark on the ocular micrometer measures: (show your work)
At 40x = 25 μm
At 100x = _________________
At 400x = _________________
At 1000x = 1 μm
Sketch your view of the Amoeba and the ocular micrometer for each total magnification. Note: the ocular micrometer does not change; however, your organism will appear larger with each objective.
40X Total Magnification:
100X Total Magnification:
400X Total Magnification:
Choose a sample and measure the same object at three different magnifications. Remember, because the object is the same, its size is not changing during this, and therefore the numbers you get should be the same, or at least close.
| Total Magnification | Number of marks on the ocular micrometer | Multiply by: | Measured size & units: |
|---|---|---|---|
| Amoeba at 40x | |||
| Amoeba at 100x | |||
| Amoeba at 400x | |||
| optional: Bacterium at 1000x |
2. Bacteria
Sketch your view of the bacteria and the ocular micrometer for under the 100x objective lens and complete the last row of the Data Table for Microorganism Size (above).
Bacterium 1000X Total Magnification:
B. Phase Contrast Microscopy - Live Specimens
Questions to think about:
- How do you determine total magnification?
2. How does the size of an organism change as you change magnification? Choose a stationary or very slow organism to focus on as you change magnifications. Use the worksheet on the following page to help you measure the size of the organism.
3. Wet mount: What is the purpose of the phase contrast? Switch back and forth between brightfield and phase contrast. How does your sample look different? Look especially at the smallest organisms on your slide. Describe the differences you see between brightfield and phase contrast under each of the objective lenses.