Biology Lab Report #1.docx

General Biology 1 Laboratory Report Date Performed: July 5, 2018 Date Submitted: July 12, 2018 Group #9 25 NEPOMUCENO, Isabella Danielle J. 26 OMPACAN, Evernim S. 27 ONA, Joaquin Miguel F.

12- STEM Pantalia

MICROSCOPIC TECHNIQUES AND MEASUREMENTS I.

II.

PROBLEM What is the difference between the Compound Light Microscope and the Stereomicroscope when it comes to their overall magnification and resolution on the subject? HYPOTHESIS The Compound Light Microscope will provide a more detailed image compared to the Stereomicroscope, because of its more powerful magnification.

III.

METHODOLOGY Materials: ● Slides/Specimen: Bee, Flower, Leaf, Euglena, Earthworm, Lily Leaf (Monocot Leaf), Nerium Leaf (Dicot Leaf) ● Materials/Equipment: Compound Light Microscope, Stereomicroscope, glass slides, pertri dishes, ruler

Procedure: The stereomicroscope was the first instrument to be used first. The bee, flower and the leaf were already placed in petri dishes next to the microscope. The group observed the specimens through the eyepiece, adjusting the zoom control, to get nearer and farther looks, and the focus knob, to get a less blurry view of the specimen, accordingly in order to get the desired distance and focus on the specimen. The group then moved to the usage of the compound light microscope for a different set of specimen already placed and labeled on glass slides. These were the euglena, earthworm, lily leaf (Monocot Leaf) and the Nerium leaf (Dicot Leaf) specimen. The light was switched on to the lowest setting at first, adjusting to a higher one as needed. The chosen slide was then placed and clipped on the stage as the LPO was set. The coarse adjustment knob was turned to raise the stage. The student then looked through the eyepiece and used the fine adjustment knob until the image was focused. Once the specimen was focused on the LPO they were able to switch to HPO to get a closer look. This process was repeated with the various slides set up by the lab technician. The working distance of the microscope was measured and recorded with a plastic ruler on the millimeter side on both the low power objective and later the high power objective. The 1

ruler was then put on the microscope’s stage as the diameter of the LPO’s field of view was estimated, adding the number of full spaces seen and the fraction of space left over. The FOV of the HPO was calculated with the following formula. Equation 1. Formula for Field of View of Higher Power Objective LPO magnification x LPO’s FOV HPO magnification The measured and calculated field of views must then be converted into micrometers by multiplying the millimeter measurement by a thousand.

IV.

DATA AND RESULTS

Table 1. Comparison between compound light microscope and stereomicroscope Features

Compound Light Microscope

Stereomicroscope

Specimen viewed

Euglena Earthworm Lily Leaf (Monocot Leaf) Nerium Leaf (Dicot Leaf) Ascaris

Bee Flower Leaf Grasshopper

Working distance (mm)

8 mm

83 mm

Magnifying power

LPO - 40x (eyepiece 4x)(LPO 10x) HPO - 160X (eyepiece 4x)(HPO 40x) Oil Immersion Objective 400x (eyepiece 4x)(OIO 100x) (Total Magnification)

100x

Movement of image compared to slide

The movement of the slide compared to the image was the opposite. If you moved the slide up, the image will show through that the specimen moved down.

The movement of the specimen moves in the same direction of the image. If you moved the specimen up, the image will show a movement up.

Specimens under compound microscope

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Specimen: Euglena w.m. HPO magnification: 160x

Specimen: Earthworm c.s. In setae HPO magnification: 160x

Specimen: Nerium leaf, c.s. (dicot leaf) HPO magnification: 160x

Specimen: Ascaris, c.s. HPO magnification: 160x

Specimen: Lily leaf, c.s. (monocot leaf) HPO magnification: 160x Specimens under stereomicroscope

Specimen: Leaf Magnification: 100x

Specimen: Flower Magnification: 100x

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Specimen: Bee Magnification: 100x

Specimen: Grasshopper Magnification: 100x

Table 2. Total magnification of objective lenses Objective

Total magnification

Low Power Objective

40x

High Power Objective

160x

Oil Immersion Objective

400x

Table 3. Microscopic measurements Specimen and field of view

Measurements

Precision of ruler (Orion) in mm

1 mm

LPO’s field of view in mm

1.5 mm

LPO’s field of view in microns (µm)

1500 µm

HPO’s field of view in microns (µm)

375 µm

Estimated size of the specimen (Euglena sp.) in µm

11.25 µm

V.

DATA ANALYSIS If a cut out letter “e” is observed under the microscope, it will be turned upside down and reversed and therefore will be seen as “ə”. This is due to the fact that the lenses used in the microscope act as both a mirror and a magnifying lens. Likewise, If the letter “e” is moved to the right, the “ə” will instead move to the left. If it is moved forward, then it will be moved backwards.

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When using a compound light microscope, microscopic organisms can be observed at a higher magnification as compared to the stereomicroscope. Its basic cell structures (ex. cell wall) can be easily identified. However, the resolution of the image produced under a compound light microscope is greatly decreased as its magnification is being increased. This means that there is only a maximum magnification (1000x) in which the image that will be observed is at its best resolution. For specimen requiring a higher magnification, this type of microscope is not recommended. Specimen to be viewed under the compound light microscope needs to be mounted first on a glass slide before viewing. On the other hand, a stereomicroscope is much easier to operate as it only has a few parts. The image produced is three dimensional. It is also very easy to view specimen using the stereomicroscope as they need not to be mounted on a slide. One major drawback of this type of microscope however is that only functions like magnifying glass, magnifying certain parts of the specimen, but could not magnify beyond that. Because of this, the small features of the parts of the specimen could not be seen properly. It will also not be appropriate to use stereo microscope when viewing transparent organisms as they will not be properly observed. The working distance pertains to the distance between the slide and the objective lens. Since a higher objective lens with a higher magnifying power is usually longer, then its distance to the specimen in the glass slide decreases. The same way that the scanner and the LPO are relatively short, then their working distance with the specimen is higher. This is the reason why the HPO and OIO are very close to touching the specimen, because it allows optimum magnification of the image. It is advisable to view the specimen first under the low power objective because it is much easier to check the specific parts of the specimen and get an overview of it by going from LPO to HPO, and focusing under the LPO first allows the specimen to be centered and set up correctly for the HPO. Starting from HPO is confusing since the specimen is already focused and very magnified without knowing its basic structure/overall appearance so it is much harder to know which parts are located on which area. Also, it also prevents the HPO from destroying the specimen since starting from LPO will allow you to slowly adjust the stage. On the other hand, if the magnification is increased, the field of view of the microscope becomes smaller. This is because when magnifying, only a small part of the whole specimen is being focused on. So when you further increased the magnification, the field of view is smaller. In changing the objective from LPO to HPO, there is a decrease in the field of view. The field of view of the HPO should be computed in a different manner as the low power objective because the normally, the FOV of the LPO is only measured by using a ruler and converting the result to micro-meter. But in HPO, the FOV is too small that the lines in the ruler will not be even seen under the microscope. A true micrometer is not available at hand so the only way to get the FOV of the HPO is to calculate by getting its ratio with the LPO and using the FOV of the LPO. The size of the specimen is estimated using the FOV of the HPO because it is the lowest objective in which you can see the specimen clearly and be able to measure it. In LPO, the specimen may be seen but it is still too small to be measured using basic measuring tools.

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Since magnification is the ratio between the image produced and the actual size of the specimen, then the two are inversely proportional. If the magnification is increased, the image observed under the microscope is therefore magnified and enlarged. However, this only means that the actual size of the magnified specimen is smaller because it needed a higher magnification to be viewed. Knowledge in micrometry is very important in research, especially if we’re dealing with unknown microorganisms. Its measurement under the microscope becomes fundamental in assessing its classification, behavior, and other characteristics of that microorganism. VI.

CONCLUSION It can be concluded that although the two microscopes have the similar resolutions when focused properly which is clear enough to examine the specimens, the compound microscope has a higher magnification compared to the stereomicroscope which allows it to view much smaller specimens that are in a slide. VII.

REFLECTION In conducting this activity, we were able to a look at different specimens with the use of a microscope. In using this instrument, we were able to look closer and see details we’d never see with the naked eye: the tiny hairs on a bee, the different shapes formed on a glass slide of bacteria and the thousands of thin lines on a leaf. Under the microscope, there was a kaleidoscope of colors and shapes that awaited us. Witnessing all this, we were struck with a sense of wonder; there is so much delicacy and artistry in even the simplest things that we are not aware of. It is possible that from molecular formations to the insides of an earthworm, there is glamor waiting to be revealed to you. The activity reminded us that there is beauty everywhere, you just have to take a closer look. As students we should learn how to take a closer look to at our lives. We tend not to notice the little things to be grateful for. They have been with us from the start and we start to take them for granted. There are plenty of things to get happiness from like helping a friend out or simply nodding at the guard. Practicing an attitude of gratitude will help us go a long way in our personal joys in life and we believe that noticing and practicing gratitude for the little things will create a more positive us for everyday living which is in itself, a success.

VIII. REFERENCES Magnification and Field of View. Lighting Technologies. Retrieved from https://www.google.com.ph/url?sa=t&source=web&rct=j&url=http://lightel.com/downloads/Ma gnification.pdf&ved=2ahUKEwifrLCu0pfcAhUVFogKHQolDEIQFjAGegQIBBAB&usg=AOv Vaw3uXJTXcgCmbEsAWMIEJMo6 Magnification and Magnifying Power. Retrieved from https://physics.stackexchange.com/questions/241095/magnification-vs-magnifying-power IX.

CONTRIBUTIONS OF MEMBERS

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Member Nepomuceno Ompacan Ona

Contributions in Making the Report Methodology, Reflection Data Analysis, Data and Results Problem, Hypothesis, Data and Results, Conclusion

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