Microscope Madness!
Name: ________________
Lab Partner: ___________
Microscope # _____
Class: SNC 2D6
Teacher: Mrs. Youssef
THE INSTRUMENT
The microscope has traditionally been the single most important tool for biologists.
Before the development of this instrument, the microscopic world was hidden. Before
the microscope, scientists’ understanding of the nature of life at the cellular level was
limited. Therefore, it is essential for every biology student to develop the skills involved
in using
the microscope.
After
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completing all the activities within this workbook, you will be able to:
Label and state the function of each part of a compound microscope.
Calculate the total magnification of a microscope.
Calculate the diameter of the field of view and measure a specimen (FOV).
Calculate the size of the specimen (SOS).
Focus in on a specimen going from low-medium-high power.
Prepare a wet mount slide for viewing under a microscope.
Stain a biological specimen for viewing under a microscope.
Calculate the magnification of the drawing (MOD)
Create a correct biological diagram of a specimen as viewed under a microscope.
PART 1: COMPONENTS AND CARE FOR THE COMPOUND MICROSCOPE
1. Label the parts of the compound microscope.
2. Match the part of the compound microscope with the function.
Part
1. _____ Stage
2. _____ Clips
3. _____ Diaphragm
4. _____ Objective Lenses
5. _____ Revolving Nosepiece
6. _____ Body Tube
7. _____ Eyepiece (ocular lens)
8. _____ Coarse-Adjustment Knob
9. _____ Fine-Adjustment Knob
10._____ Source
Function
A. May be an electric light bulb or a mirror
that can be angled to direct light through
the object being viewed
B. Contains the eyepiece (ocular lens);
supports the objective lenses
C. The part you look through to view the
object; magnifies the image of the object,
usually by 10X
D. Controls the amount of light that reaches
the object being viewed
E. Supports the microscope slide; has a
central opening that allows light to pass
through the slide
F. Moves the stage up or down to get the
object into focus
G. Holds the objective lenses; rotates,
allowing the objective lenses to be
changed
H. Moves the stage up or down to get the
object into sharp focus
I. Magnifies the object; have three possible
magnifications: low power (4X), medium
power (10X), and high power (40X)
J. Holds the slide in position on the stage
3. Review the following checklist for the proper use of the microscope.
Rules for Care and Use
 Carry the microscope with both hands, one on the arm & one under the base.
 Keep the microscope away from the edge of the table.
 Lower the stage, set to low power and turn on light before looking into eyepiece.
 Move slide into position and look at all specimens under low power first.
 Use coarse adjustment knob before the fine adjustment knob to focus on
specimen.
 Never use the coarse adjustment knob under high power.
 Lower stage before changing to higher power lens.
 Always view the slide/lenses from the side when on medium and high power.
 Lower stage, set to low power, turn off light, wrap cord around, and put on cover
before putting microscope away.
Activity 1: Observing a Hair Under Low, Medium and High Power
4. Read pg. 606 “Preparing a Dry Mount”.
5. Make a dry mount of your own hair. If you are having trouble keeping the hair in
place, you may use two pieces of tape in order to secure it down onto the slide.
6. With your lab partner, use the “Checklist: Using the Microscope” worksheet
in order to practice focusing on a specimen under low, medium and high power.
7. Another student will assess your ability to use the microscope.
PART 2 – MICROSCOPE CALCULATIONS
Aspects of the Microscope
Inversion: the image shown through a microscope is inverted, or flipped around in
two directions.
Magnification: How many times larger the image of the specimen in compared to the
actual size of the specimen.
Total Magnification: Compound microscopes use multiple lenses to produce
an increase in magnification. Multiply the objective lens magnification by the
eyepiece magnification (10X).
Total Magnification = Magnification of Objective X Magnification of Eyepiece
E.g. If the eyepiece lens enlarges 10X and the objective lens enlarges 40X, the
total magnification is 400X.
Resolution/Resolving Power: a measure of the clarity of the image. The minimum
distance two points can be separated and still be distinguished as two separate points.
A high resolution allows the viewer to see two objects that are very close together as
two objects rather than as one.
E.g. The resolving power of the eye is 0.1 mm, a compound microscope = 0.000 2 mm,
an electron microscope = 0.000 000 5 mm
Field of view (FOV): The area visible through the eyepiece. Field of view decreases
as magnification increases. You must have your specimen in the centre of the FOV when
you increase magnification.
Diameter of Field of View: Because objects examined under a microscope are
usually quite small, biologists find it convenient to use units called micrometers or
microns (µm). The micron (µm) = 1/1000 of a mm.
Size of Specimen (SOS): To estimate the size of a specimen (SOS) in the field of
view, use the diameter of the FOV for the appropriate lens divided by the number of
times that you estimate that the specimen would fit across the entire FOV.
SOS = Diameter of FOV / # of times the specimen fits across the FOV
For example, if the diameter of the
FOV is 500µm…
500µm
the estimated size of the specimen
(SOS) is 500µm/3.5 = 142.9 µm.
Activity 2: Calculating Field of View (FOV) under Low, Medium and High Power
Using your microscope, fill in the chart below as you follow the directions.
Lens
Low Power (X4)
Medium Power (X10)
Measurement or Calculation
Diameter of Field of View
of Diameter of Field of View
(FOV) in µm.
(FOV) in mm
(measured)
X 1000
(divide measured above by
2.5)
X 1000
High Power (X40)
(divide measured above by
10)
X 1000
1. Place a plastic ruler (showing millimeters) on the stage.
2. Using the low powered objective, obtain a well-defined image of the divisions of
the ruler.
3. Carefully move the ruler until its marked edge passes through the part of the field
of view (across the centre of the FOV).
4. Count the number of divisions (mm). This is the diameter of the FOV on low
power in millimeters.
5. Convert the diameter of the FOV (in mm) into microns (µm) (i.e. multiply by
1000).
6. Divide the diameter of the FOV (in µm from #5) by 2.5 to get the FOV diameter
for medium power.
7. Divide your diameter of the FOV (in µm from #5) by 10 to get the FOV diameter
for high power.
Question1: What do you notice about the relationship between the magnification and
the diameter of the field of view (FOV)?
Question 2: How large is the field of view for the microscope shown below?
a) Find the FOV diameter for lower power in mm and µm.
b) Calculate the FOV diameter for the medium power in mm and
µm.
c) Calculate the FOV diameter for the high power in mm and µm.
Activity 3: Aspects of Microscope and Estimating Size of Specimen (SOS)
1. First, you fill in the chart based upon your calculations for FOV from Activity 2.
Measurement or Calculation
Diameter of Field of View
Lens
of Diameter of Field of View
(FOV) in µm.
(FOV) in mm
Low Power (X4)
(measured)
X 1000
Medium Power (X10)
(divide measured above by
2.5)
X 1000
High Power (X40)
(divide measured above by
10)
X 1000
2. Read pg. 606 in your textbook, “Preparing a Wet Mount”.
3. Cut out a letter “e” from a newspaper and prepare a wet mount using a
microscope slide and cover slip. Place the slide with the “e” right side up on the
microscope stage. Secure the slide with the stage clips.
4. Focus on low power. On the sheet provided, draw a diagram of what you see
under low, medium and low power.
5. Estimate the size of a specimen (SOS) on the high magnification view (show
work). Make sure you indicate which part of the specimen you measure.
Question 1: Lift the stage clips and move the slide in the following directions. While
viewing the letter “e”, describe the movement of the image.
Actual Movment of the Letter
a)
b)
c)
d)
e)
f)
To the left
To the right
Away from you
Towards you
Clockwise rotation
Counterclockwise rotation
Apparent Movement of the Image
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PART 3: MAKING FORMAL BIOLIGAL DRAWINGS
 On blank paper, use a sharp lead pencil for drawings, titles and labels
 Draw what you see, not what you think should be there.
 Drawings should be as simple as possible with clear-cut lines (do not sketch).
 Do not shade your drawings. If you wish to indicate a darker area, use dots
(stipple).
 Drawings should be large enough to show all parts without crowding (i.e ½ the
page). Room should be left at the bottom for calculations.
 Use a ruler for labeled lines. Guidelines to the labeled parts should be parallel to
each other, without crossing.
 The lettering should be horizontal. All labels for organelles should be to the right
of the drawing.
 All drawings must be titled. The printed and underlined title appears immediately
above the drawing. The title should be as specific as possible. The magnification
of the drawing (MOD) must be beside the title in brackets.
Magnification of Drawing (MOD) or scale: How much larger is your drawing
compared to the actual specimen?
MOD = diameter of specimen in drawing (DOD) / size of specimen (SOS)
E.g. If the SOS is 1.5 mm and the DOD is 135 as shown below…
Specimen
Drawing of Specimen
MOD = 135 mm/1.5 mm
= 90X.
This means that the drawing
is 90X larger than the actual
specimen.
1.5 mm
Remember that the MOD
always follows the title of the
diagram in parentheses!
135 mm
SAMPLE BIOLOGICAL DIAGRAM:
Wet Mount Slide of a Potato Cell (225X)
Stain: Iodine
Total Magnification of Microscope: 400X
Name: Stu Dent
Date: February 14, 2013
Calculations:
Size of Specimen (SOS) = Diameter of Field of View (FOV)
# of time specimen fits across FOV
= 0.4 mm / 2
= 0.2 (width)
Magnification of Drawing (scale)= Diameter of specimen in drawing
Size of Specimen (SOS)
= 45 mm / 0.2 mm
= 225 X
PART 4: OBSERVING PLANT AND ANIMAL CELLS – LAB EVALUATION
Follow the instructions on page 34-35.
Mrs. Youssef will evaluate only one biological diagram. One lab partner will hand in the
drawing of the plant cell (viewed under medium power), and the other partner will hand
in their animal cell drawing (viewed under medium power).
While you will only be marked on only one drawing, you are still responsible for
observing and making notes/rough drawings on every slide observed (see following
page). You will both have to answer the lab questions as well.
Evaluation of Drawings (Communication – 18 marks)
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Drawing done on blank paper
Drawing done with a sharp pencil
Firm, clear lines (no sketching)
No shading/colour used (stipples allowed)
Only relevant and easily seen details are included
Large diagram (1/2 the page)
Labels are neatly printed
Labels all located to the right of the drawing
Labels listed in an even column (lined up)
Label lines are parallel and done with a ruler
Label lines do not cross
Name and date located on the top right corner
Stain and total magnification of microscope on top left corner
Magnification of Drawing (MOD) located beside main title in parentheses
Main titled underlined
Appropriate title located at the top
Calculations for size of specimen (SOS) and magnification of drawing - scale
(MOD) are present at the bottom of the page, below the drawing (2 marks)
Evaluations of Calculations (Thinking – 4 marks)
Evaluation of Questions (Thinking – 18 marks)
Rough Drawings of Plant and Animal Cells
Onion Cells
Mag.: __________
Mag.: __________
Mag.: __________
Size: ___________
Size: ___________
Size: __________
Mag.: __________
Mag.: __________
Mag.: __________
Size: ___________
Size: ___________
Size: __________
Mag.: __________
Mag.: __________
Mag.: __________
Size: ___________
Size: ___________
Size: __________
Epithelial Cells (from Cheek)
Yeast Cells
Lab Questions (2 marks each – T/I)
Answer the following questions in full sentences on a separate sheet of paper.
1. Which has a larger field of view – the low power or high power objective?
2. A slide of plant cells was viewed under medium power as shown below. In each
of the other diagrams, draw what you would see for the same slide viewed under
the other lenses.
3. Explain why specimens must be “thin” to be viewed under a microscope.
4. Why do you begin viewing under low power lenses first?
5. Why do you only use the fine adjustment knob with the highest power objective
lens?
6. Compare the sizes and shapes of the types of cells examined (i.e. animal, plant,
yeast cells).
7. Look at the cell parts on pg. 30 in your text. Did you see evidence of the nucleus
in the cells you examined?
8. What do you think accounts for the difference in shape between the plant cells
and other types of cells?
9. What difference, if any, did you notice in the cells before and after they were
stained with iodine? Why were you advised to stain the cells?
10.Most books state that plant cells contain chloroplasts. Based upon your
observations, is this statement correct? Support and explain your answer.
11.Would you expect all animal cells to look the same? Explain your answer.
MICROSCOPE CALCULATIONS EXTRA PRACTICE
Answer the following questions on a separate sheet of paper.
1. Calculate total magnification of the microscope.
Ocular
Objective
10X
4X
15X
10X
5X
12X
10X
10X
10X
40X
Total Magnification
2. What are the possible magnifications of a microscope with an ocular marked 10X
and objectives marked 5X, 15X, 30X and 60X?
3. Convert the following measurements: 1mm = 1000μm
a. 9.2 mm =
b. 5900 μm =
c. 0.083 mm =
d. 61000 μm=
4. Estimating Size of Specimen (SOS):
a. The field of view is 2500um. If a cell takes up 1/5 of the field of view, how
long is the cell?
b. A student counts 50 cells across the diameter of the field of view, and
there are 70 rows of cells. If the diameter of the field of view is 3500 μm,
what is the length and width of the cells?
5. Calculate the field of view (FOV).
a. Low power (4X): 4.5 mm = _______ µm
b. Medium power (10X): ________ mm = _______ µm
c. High Power (40X): ________ mm = _______ µm
6. Magnification of Drawing (MOD) or scale:
a. An organism has an actual length of 0.050mm. If you draw a diagram
which is 75.0mm, what is the magnification?
b. An organism has an actual length of 0.060mm. If you draw a diagram
which is 36mm, what is the magnification?
c. An object has an actual length of 0.025mm. If you use a scale of 1:1000,
what will be the size of the drawing?
d. An organism has an actual length of 0.033mm. If you use a scale of 1:250,
what will be the size of the drawing?