Intro To Microscope Assignment S21 PDF

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]Summer 2021- BIO 010 Intro to Biology BASIC INTRODUCTION TO THE USE OF THE COMPOUND MICROSCOPE (15 points)

Assignment due on D2L in the assignment folder “Microscope” by 05/30 at 11:59 PM OVERVIEW Follow along in this online exercise, with guided instruction covering the basics of light microscopy, comparable to what you would learn in a seated lab. You will identify components of the microscope, understand the functions of those components, learn how to focus in on a specimen, and review proper care and maintenance. LEARNING OBJECTIVES • Identify the parts of the light microscope and describe the function of each. • List the steps in focusing a light microscope. • Describe how to properly handle the light microscope, focus slides, and clean the microscope when finished. BACKGROUND The microscope is one of biology’s most important tools. Without it we would lack most of our knowledge of living things too small to be seen by the naked eye. Information made available through instruments has given rise to research that would never have been undertaken if these tools had not existed. For example, our understanding of how all living things are composed of cells and of how cells work would have been impossible without the microscope. The microscope is also useful for learning biological concepts and techniques. There are many kinds of microscopes in use today with magnifications ranging from 2X to over 100,000X. A magnifying glass is the simplest kind of magnifying lens. However, when we use the word “microscope,” we usually are referring to an instrument made up of a series of lenses held together in a tube. The compound microscope will be the first microscope you will use in the lab. Instruments of this type usually provide magnifications varying from about 40X to 1000X. The electron microscope can magnify over 100,000X. The type of compound microscope commonly used in the biology laboratory is the monocular compound microscope. It is called “monocular” because the image is viewed with one eye. The term “compound” refers to the image being produced by the interaction of several lenses. Most objects examined under the monocular compound microscope must be so small or thin that light can pass through them to your eye. You are able to see and distinguish form and structure in such objects because some of their parts absorb more light than others. Objects seen in this way under the microscope are said to be observed by transmitted light. Terms associated with the microscope: During the course of the lab you should become familiar with terms often used by biologists studying the microscopic structure of organisms. These include the following: Magnification: The degree to which an object’s image is enlarged under the microscope Resolution: The ability of a microscope to reveal fine detail which permits us to clearly separate small details present in the image of the object Working Distance: The distance between the objective and the cover slip or the specimen when lenses are in correct focus. The distance varies with each objective magnification

Parfocal: A magnification system where little adjustment in focus must be made when changing from one objective to another Field of View: The circle of light seen when looking through the microscope

PROCEDURE 1: Introduction to the Microscope and its Parts 1) Go to http://www.ncbionetwork.org/iet/microscope/. 2) Click on the Guide link ( bottom of the home page ). 3) Click through the six parts of the Guide, starting with the Introduction. You can use the arrows at the

bottom of the Guide box to guide you through the chapters. 4) When you have completed all six sections, click Close. 5) Next click on the Learn link (bottom of the page), which will take you to an image of a microscope

with question marks. 6) Starting at the top of the microscope, click on the question marks identifying the parts of the

microscope. 7) Read the description of the part of the microscope and take notes as needed. 8) Continue clicking on question marks until all turn to green check marks. a) Do not forget to click on the question marks for items associated with the microscope. b) You may click on any green check mark to review any part of the microscope. c) Use the Microscope Parts checklist on the next page to ensure all parts have been identified. 9)

Click on the Next button (bottom right). 10) Start on the left and click on the question mark. When the lens enlarges, click on each question mark

until each turns into a green check mark. Read the descriptions and take notes as needed. 11) Click on the Next button (bottom right). 12) Click on the Dry Slide and Oiled Slide buttons to see the difference in why immersion oil is used for

the 100X objective lens. 13) Click on the Next button ( bottom right ). 14) Click on the Eyepiece Options and Lens Options to learn about calculating total magnification. Try

all combinations and see how the Letter E slide image changes. 15) Click on the Next button (bottom right) to return to the home page. 16) Answer the provided questions

on the next page. *Be aware! Depending on its age, manufacturer, and cost, in a laboratory a compound microscope may have only some of the features discussed in this section.

MICROSCOPE PARTS (7.5 points) Identify all parts of the microscope and associated items. _k__ On/ Off switch __C_ Eyepiece/ Ocular lens

__J_ Arm

__F_ Nosepiece _D__ Stage

__G_ Objective lenses __H_ Diaphragm _E__ Stage adjustment knob _M__ Base

__L_ Coarse adjustment knob

__A_ Lens paper

__N_ Fine adjustment knob

_B__ Immersion oil

__P_ Slide/ slide box

_O__ Kimwipes

QUESTIONS (6 points) 1) What is the typical magnification of an ocular lens? What other magnifications are possible?

The ocular eyepiece usually magnifies the image 10X, and the objectives magnify the image 4X, 10X, 40X and 100X. For example, when using the 40X objective and a 10X ocular, the total magnification would be: 4010=400. Total magnification is objective eyepiece

2) What are the magnification abilities of each of the objective lenses? Also, what is the total

magnification with each objective? The objective and ocular lenses are responsible for magnifying the image of the specimen being viewed. So for 10X objective and 10X ocular, Total magnification = 10 X 10 = 100X (this means that the image being viewed will appear to be 100 times its actual size). a) Scanning ( small lens ), red ring =4x b) Low-power ( medium lens ), yellow ring =10x c) High-power ( large lens ), blue ring =40x d) Oil immersion ( largest lens ), white ring =100x

3) Why do you use immersion oil with 100X objective lens? i: air has a lower refractive index than glass, light waves have a tendency to bend and scatter as they pass through the air from the glass slide of the objective lens. ii: the immersion oil takes away the "air" space between the slide and the objective to not refract the light

4) What is the total magnification of a sample with an ocular lens power of 15X and using a 40X

objective lens?

15x and 40x is 600 (15x40).

5) What is a diaphragm? What does it do? It controls the amount and shape of the light that travels through the condenser lens and eventually passes through the specimen by expanding and contracting the diaphragm blades that resemble the iris of an eye.

PROCEDURE 2: How to use a compound microscope to view slides 1) 2) 3) 4) 5)

Click on the Explore link ( bottom of the home page ). Click on the question mark 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. NOTE: Always begin examining slides with the lowest power objective.

6) Use the slider under Coarse Focus to find the E.

NOTE: The coarse adjustment knob should only be used when you are viewing a specimen with the 4X objective lens. 7) Then use the slider under Fine Focus to make the image “crisp and clear.” 8) You can click on the E in the viewing window to move the image and visualize different parts. Sketch

your view of the letter E at 4X in the results area. 9) Next click on the 10X circle. The nosepiece on the microscope will rotate automatically. 10) Repeat steps 6 – 8 to see part of the E. Sketch your view of the letter E at 10X in the results area. 11) Click on the 40X circle and repeat steps 7 & 8. You may need to use the slider under Light Adjustment

for better visualization. Sketch your view of the letter E at 40X in the results area. Click on the 100X circle. A notice to add immersion oil will open. 12) Click on the question mark on the immersion oil bottles to add oil to the microscope. 13) Repeat steps 7 & 8. You may need to use the slider under Light Adjustment again for better

visualization. Sketch your view of the letter E at 100X in the results area. 14) When you have visualized the Letter E slide using all 4 objective lenses, click on Remove Slide ( top

right ). 15) Read the notice about using lens paper to clean the immersion oil off the microscope and click on the

question mark over the lens paper. Choose wisely! 16) Click on the Main button ( bottom left corner ) to return to the home page.

RESULTS: Sketch the letter “e” at each of the magnifications shown below (0.5 point)

Letter “e” at 4X

Letter “e” at 10X

Letter “e” at 40X

QUESTIONS (1 point) 1) What did you notice about the letter E when you increased in magnification from the 4x to the 10x and then to the 40X: a) Did the size (magnification) increase or decrease?

It increase the size I saw piece of black in slide

b) Could you see more of the entire letter or less?

No

KNOWLEDGE CHECK 1) 2) 3) 4) 5) 6)

Click on the Test button (bottom of home page). In the Challenge Mode window, click on Care & Usage link and answer the questions. If you get a 75% or better, click Choose Test. If you do not get a 75% or better, click Try Again. Next choose the Calculating Magnif ication link and repeat #3. Then choose the Terminology link and repeat #3. Click on the Main button ( bottom left corner ) to return to the home page.

This lab was adapted from ncbionetwork.org...