Microscope Lab Activity

Emily Cocq 4B Mr. Boyer Biology I Microscope Lab Activity

Introduction:

Microscopes are an amazing invention; able to observe specimens to the tiniest degree. No matter how small, we are able to view an endless amount of life forms, all because of microscopic technology. Scientists are opened to a whole new world, things undiscovered, things never seen before. Now it is open to everyone. In our very Biology I class, we are privileged to witness one of these man-made wonders, and it can only make us wonder how much more we don’t know. We can only learn through observation.

Procedures: Part I- Handling the Microscope 5. Examine the microscope and give the function of each of the parts Part of Microscope Function Ocular Lens Views the specimen on the stage. Revolving nosepiece Turns the objective lenses. Objective lenses (Low, Medium, High Used to view the specimen at different Power) levels Body Tube Holds the revolving nosepiece and the objective lenses. Stage Supports the slide. Arm Connects the base and barrel. Iris Diaphragm Regulates the light. Coarse focus knob Raises and lowers the stage for focusing. Fine focus knob Slightly moves the stage to sharpen the image. Projection lens Projects light up to the stage. Base Supports the microscope. Power switch Turns the projection on and off.

Part II- Wet Mount Letter “e” 6. Describe the relationship between what you see through the eyepiece and what you see on the stage. On the stage, the specimen looks very small to notice any detail, if it can be seen at all. Through the eyepiece, everything is magnified, and it is as if you are looking at a whole new subject. Colors are intensified, and the insides are all illuminated through bright light.

7. Looking through the eyepiece, move the slide to the upper right area of the stage. What direction does the image move? To the upper left.

8. Now, move it to the lower left side of the stage. What direction does the image move? To the lower right.

10. Locate the diaphragm under the stage. Move it and record the changes in light intensity as you do so. As you move it to one side, the light becomes darker and the insides of the specimen are not as illuminated. If you move it to the other side, the light becomes brighter and the insides of the specimen are illuminated and clear.

Letter “e” Part III- Plant and Animal Close-Up Cheek Cells

Pond Scum Potato Sample Prepared Slides

Earthworm Intestine Region

Hydra Budding Adult Spirogyra Questions

1. Locate the numbers on the eyepiece and the low power objective and fill in the blanks below. Eyepiece magnification ______20X______(X) Objective magnification ______40X______= Total Magnification ______800X______

2. Do the same for the high power objective.

Eyepiece magnification ______20X______(X) Objective magnification ______400X______= Total Magnification ______8000X______

3. Write out the rule for determining total magnification of a compound microscope. Total magnification of a compound microscope is the product of the eyepiece magnification and the objective magnification (If there are two objective magnifications, then the two should be multiplied together also).

Conclusion: From working with microscopes, we have learned more about the specimens we observed. We also learned how to handle microscopes, using the proper techniques with the Coarse and Fine focus knobs, as well as other parts. We learned the safe procedures when making a slide and inserting it on the stage properly. Overall, this has been a great learning experience, to learn about the microscopes and the specimens we’ve studied with it. No matter how much we already knew about microscopes, we explored deeper and discovered so many new things.

Conclusion Questions: 1. Carry the microscope with both hands; one on its arm and one on its base. Make sure that when adjusting any of the focus knobs to not hit the objective lens, as it will damage it permanently.

2. A light microscope is also called a compound microscope, because it uses more than one lens.

3. Images observed under a light microscope are reversed and inverted, because, to get a clear look at a specimen, the objective lenses have to have very short focal lengths. When light passes through the specimen and into the objective, it passes the focal length, making the image invert and reverse. 4. The specimen must be centered in the field of view on low power before going to high power so that the viewer can find the specimen easily, then switch to a higher power, now focused on the object, if they want.

a. Eyepiece magnification (x) Objective magnification = Total magnification

20X (x) 10X = 200X b. Eyepiece magnification (x) Objective magnification = Total magnification 20X (x) 43X= 860X

6. First, cut out a letter “e” from a piece of newspaper and place it on a glass slide. Then, use the dropper to put a drop of water onto the slide, and stick the “e” in place with the cover slip. To add the stain, put a drop of iodine in the solution and place the cover slip back on, cleaning off the residue with a paper towel or tissue. 7. When going from low power to high power on a compound microscope, the field of view becomes greater and the amount of light is greater as well, because of how close the objective lens is to the projected light.

8. The microscope user could adjust the diaphragm to suit the lighting to the specimen.

9. Under high power, you cannot use the Coarse focus knob, for it might damage the objective lens, therefore you must use the Fine focus knob. Also, under high power, it is harder to focus in on the object, so you must find the object in the field of view on low power first.

10. A stereomicroscope gives a low-power view of the subject, while a compound microscope can view both low power and high-power. 11. An electron microscope is a microscope that only works with nonliving materials, but has a very good resolution and can be useful in the science world in order to observe things that have died but still wish to be used in experiments.

Timeline 1590 – Compound microscope invented by Hans and Zacharias Jansen, Dutch spectacle maker 1827 – Achromatic microscope lens developed by Giovanni Amici 1838 – Cell theory proposed by Schleiden and Schwann

1882 – Movement of cells within living organisms observed by Metchnikoff 1932 – Electron microscope invented by Ernst Ruska