Procedure
Part A:
‍Parts of the Compound Microscope

Use the terms listed here to label the figure of the microscope below.  Fill these answers in for Part A of your Lab Report.
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A picture of a compound light microscope with numbered arrows pointing to parts 1-12. Use the list of parts provided to identify the parts of the microscope. The labeled parts are: 1. the lens the viewer looks through to see the specimen, 2. a rotating turret that houses the objective lenses, 3. cylindrical lens which can be rotated that range in power from 4X to 100X, 4. The flat platform where the slide is placed, 5. gathers and focuses light from the lamp onto the specimen being viewed, 6. knob that controls the amount of light reaching the specimen, 7. knobs that move the stage left and right or up and down, 8. the light source for a microscope, 9. connects the eyepiece to the objective lenses, 10. connects the body tube to the base of the microscope, 11. brings the specimen into general focus, 12. fine-tunes the focus and increases the detail of the specimen.

• Arm
• Condenser
• Coarse focus knob
• Fine focus knob
• Head
• Iris diaphragm
• Iris diaphragm lever
• Lamp
• Objective lenses
• Ocular lenses
• Rotating nosepiece
• Stage






Part B - Using The Compound Light Microscope

• Use the information provided in the Lab 2 reading, these slides of the printed letter "e", and Figure 2.2 (below), and  to answer questions in Part B of your Lab 2 Lab Report.
• Use the Black arrow to move from one slide to the next.
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This is  the orientation of the letter "e" when it is placed on the microscope stage. Notice what happens to the orientation (direction) of this image when viewed through the microscope on the next slides.

the figure shows the unturned orientation of the lowercase English alphabet letter “e” when placed on a compound microscope stage.
The letter e and viewed under 4X objective lens appears upside-down and backwards and occupies almost the entire field of view.
The letter e and viewed under 10X objective lens. Image is still inverted; you cannot see the entire letter e in the field of view any more. Ink is obviously blotchy, not smooth.
The letter e and viewed under 40X objective lens. Image is still inverted; you can only see a small part of the letter e. The ink is clearly not smooth, but instead patches or blotches of ink spots.

Use Figure 2.2 and the definition of working distance provided in Lab 2 reading the to answers question 16 in your Lab Report. The arrow is showing the working distance for one of the lenses.

The figure shows four objective lenses 4X, 10X, 40X, and 100X. An example of working distance is shown by an arrow between the slide and 4X lens. The image shows less space between the bottom of the lens and the slide as the magnification increases. At 100X the working distance approaches zero.

                                       Figure 2.2

Part C:
‍Prokaryotic cells: Human Mouth Bacteria

• Many of the mutualistic microorganisms that populate humans live in the digestive tract. Most of these microorganisms are members of the Domain Bacteria. There are many bacteria that live in the human mouth, no matter how clean you think your mouth is they are there.
• The variety of bacterial populations in the mouth is dependent on factors such as diet, toothpaste, mouthwashes, and cigarette smoke.
• Some environments will support large diverse bacterial communities while other will support very few.
• In the exercise, you will visualize the bacteria living in a mouth.

• Below is an image of bacteria taken from someone's mouth.
• The bacteria were 'fixed' to a slide and stained to make them easier to see.
• This image was taken with the oil immersion (100X) lens in place.
• You would have seen an image like this one had you taken bacteria from your own mouth.
• Each one of those tiny spheres and rods is an individual bacterial cell.
•There are many tiny bacterial cells in this field of view.
• No matter how clean you think your mouth is there are bacteria in there!
• Use this image to answer questions in Part C of the Lab Report.

Gram stained bacteria from mouth, gram positive and gram negative bacteria with different morphology can be observed here seen through a compound light microscope under oil immersion lens (100X). The cells are too small to see any cellular detail.

Part D:
‍Eukaryotic cells: Protists in Pond Water

Watch Pond water VideoSome of the protists you may see in pond water mentioned in Fig 2.3 include the bi-lobed green algae called algae cosmarium, the slipper-shaped motile ciliated paramecium, the motile photosynthetic discoidal unicellular organism called euglena, the filamentous green alga called spirogyra, the spherical colonial green alga called volvox, the horn-shaped or trumpet-like ciliate, organism called stentor, the pennate diatom called nitzchia, the filamentous segmented green alga called penium, the oval/bean-shaped green alga called navicula, the bell-shaped ciliates organism with stalks called vorticella, and the star-shaped green algae called stairatrum.


• Watch the video below and try to identify as many of the organisms in the video as you can.
• Use Figure 2.3 to help you identify the organisms in pond water video.
• Then select one of the organisms you identified and observe it in more detail.
NOTE - not all of the organisms shown in Figure 2.3 are in the video.







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After you have submitted your Lab Report Via Google please go to Blackboard, select the Lecture & Lab Materials folder for this week and then select "Lab 2 Lab Report: Post Statement here when completed". Select "Write Submission" and type in "I have submitted my Lab Report Via Google docs"
This will allow me to enter a grade that you can see on Blackboard in your grade book for each lab.

Non-majors College Biology Lab Manual © 2021 by Marie McGovern Ph.D. is licensed under CC BY-NC 4.0