Virtual Lab: Introduction to the Microscope Objectives
• Explain the three parts of cell theory.
• Identify the different parts of a microscope.
• Explain why the microscope was invented and how it helped develop the cell theory.
Internet Resources: The Wacky History of Cell Theory OR http://ed.ted.com/lessons/the-wacky-history-of-cell-theory Virtual Microscope OR http://www.udel.edu/biology/ketcham/microscope/scope.html History of The Cell Theory Procedure:
1. Watch the following video: The Wacky History of Cell Theory (http://ed.ted.com/lessons/the-wacky-history-of-cell-theory)
2. After watching the video, answer the following questions. (HINT!!! You may need to watch the video more than once.)
a. What are the three parts of the cell theory?
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b. How did Leeuwenhoek discover bacteria?
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c. Before it was called “bacteria,” what was it called? _____________________________
d. Who came up with the term “cell?” _________________________________________
The Virtual Microscope Procedure
1. Begin by accessing this link: Virtual Microscope (http://www.udel.edu/biology/ketcham/microscope/scope.html
2. Make sure the volume is on. Click on the “Start Tour” at the bottom right of the “Getting Started” box.
3. 3. When asked to select a slide, begin with the green specimen- Onion Root Tip. This is the easiest to observe (2nd from top).
4. Click on the “Switch Objectives” tutorial under the “Getting Started” box. LISTEN!
5. Follow the tutorial prompts to learn how to center the slide and focus your specimen. (HINT!!! Use the checklist box on the left side of the screen to monitor your progress.)
6. Once your specimen is in focus using the 4X lens, use the revolving nosepiece at the bottom left of your screen to move the 10X lens into place. Use the fine focus to adjust.
CHECKPOINT: Which lens does the tutorial tell you to start with? _______x
CHECKPOINT: Describe the difference between the coarse focus and the fine focus.
CHECKPOINT: What are you supposed to do with the coarse focus?
CHECKPOINT: What happens if you try to use the coarse adjustment when the 10X lens is in place?
7. Draw the Onion Root Tip using 10x AND 100x magnification.
8. Follow the same procedure for the Bacterial Capsules and Cheek Cells Slides
a. Specimen: Bacterial capsule @ 40x AND 100x magnification
b. Specimen: Cheek cells @ 10x AND 40x magnification
CHECKPOINT: What happens to your image if you try to magnify it using 40x or 100x?
Analysis and Review
Use the information from “History of The Cell Theory” and “Virtual Microscope” lab activities to answer the questions below.
1. What objective lens you should have in place to begin looking at your specimen? Explain why.
2. Explain why this statement is right or wrong. (Yes, make a decision and defend your choice.) “You only use the coarse focus knob when you have the 4X scanning objective in place.”
3. Assuming the light is on and the oculars are in place, what are the next 2 steps? Describe what to do if more light is needed to view the specimen.
