Microsopy Lab

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School

Centennial College *

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182

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Biology

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Apr 3, 2024

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docx

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GS 182 Lab 2 – Microscopy This lab is out of 31 marks and is worth 10% of your final grade. Checklist for the lab:  Watch “How to Use and Care for a Microscope” at https://youtu.be/ROsc-IrJJ6M  Visit https://www.ncbionetwork.org/iet/microscope/ to use the virtual microscope  Complete all the questions (highlighted in yellow) in this document by typing the answer in the box below each question, please do not exceed the text limit for each question  Submit the completed lab on eCentennial before the deadline posted by your teacher Objective 1: Learn the names and functions of various parts of a compound light microscope  Launch the following website: o https ://www.ncbionetwork.org/iet/microscope /  Click on “Learn”  Click on question marks within outlined area to investigate microscope parts 1. Identify all parts of the microscope and associate items by typing the corresponding letter after each of the following parts/items. First one is already done for you. [4 marks] On/off switch K Diaphragm H Coarse Adjustment knob L Arm J Base M Fine adjustment knob N Objective Lenses G Stage D Eyepiece/ Ocular Lens C

GS 182 Lab 2 – Microscopy Objective 2: Investigate the relationship between image created by the microscope and the actual object  Click on “Main” to return to main menu  Click on “Explore”  Click on the slide box  In the Slide Catalog, click on the Sample Slides.  Click on the Letter E slide. It will automatically be placed on the stage of the microscope.  When the Microscope View window opens, make sure that the 4X circle is highlighted in blue.  Use the slider under Coarse Focus to focus on the “e”.  Then use the slider under Fine Focus to make the image “sharp” (The edges should be clear and crisp)  You can click on the “e” in the viewing window to move the image and visualize different parts. 2. Centre the image and take a screenshot of the letter “e” at 4X, 10x and 40x. Paste your screenshots below [3 marks] Letter “e” at 4x Letter “e” at 10x Letter “e” at 40x 3. [3 marks] b) What is the relationship between the image (what you see through the eyepiece) and the object (the letter on the slide)? c) Besides the letter “e”, give 2 other letters that would also be appropriate for this activity, explain your reasoning. Limit your answer to 3 to 4 sentences) 3b) The image is flipped, meaning it’s upside down and reversed. Another way to think of it, is that it’s been turned around completely by 180 degrees. The lenses in the microscope work like mirrors, but instead of reflecting light, they refract it, causing the image to appear flipped. 3c) Besides the letter "e," “r” and “g” are other letters that would also be appropriate for this activity. These letters possess distinct features and provide clear reference points, making them

GS 182 Lab 2 – Microscopy easy to distinguish even when flipped and inverted. This makes them helpful when looking at things under a microscope. Objective 3: Understand how to calculate total magnification and diameter of FOV  By default, the ocular lens (eyepiece) has a magnification of 10x. The total magnification of the specimen can be calculated by multiplying the ocular lens magnification with the objective lens magnification. 4. Calculate the total magnification when viewing specimen using the 3 objective lens. [3 marks] Ocular lens magnification Objective lens magnification Total magnification Low power objective 10x 4x 40x Medium power objective 10x 10x 100x High power objective 10x 40x 400x  It is important to know the diameter of the field of view (dFOV) at a given magnification. This information allows us to measure the size of the specimen (e.g. a cell).  To find out the dFOV, we can place a ruler under the microscope.  Figure 1 below shows what you can see using the 4x objective lens (total of 40x magnification). The field of view fits approximately 3½ increments of the ruler, this is equivalent to equal to a length of 3.5 mm. Figure 1 - Ruler Under Microscope  It is common practice to report diameter of field of view in micrometer (  m). There are 1000  m in 1 mm, therefore the diameter of the field of view in figure 1 is equal to 3500  m.

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