GREEN RIVER COMMUNITY COLLEGE
IDS Unit 1
MICROSCOPE LAB 2
In the first portion of this lab you will be introduced to the stereomicroscope. In the
second portion you will use both a stereomicroscope and a compound microscope to
observe and draw various organisms and cells.
Stereomicroscope
Introduction: The stereoscopic (Dissecting or Binocular) microscope or
stereomicroscope has advantages for some types of microscopic work. It consists of
two complete microscopes. One for each eye, united to form a single instrument.
Each of these microscopes provides separate and somewhat different images, since the
object is viewed from slightly different angles. This binocular feature creates a
stereoscopic effect. In our minds we are able to combine and interpret these images so
that we observe the object in three dimensions – length, width, and depth.
The stereomicroscope like the compound microscope may be used to view objects by
transmitted light. Usually, however, we use the stereomicroscope to look at objects by
reflected light. This means that the observer looks at an object as she/he might view a
book or her/his own hand. The object is visible because light is reflected from its
surface. The stereomicroscope is particularly useful for studying things that are too
small to be observed with the unaided eye but too large to be seen as a whole with the
compound microscope. The stereomicroscope has a relatively low magnification, 7X
to 30X and is used for viewing and manipulating relatively large objects.
The stereoscopic microscope is similar to the compound microscope except in the
following ways. (1) The depth of field is much greater than with the compound
microscope and so you view objects in three dimensions, and (2) the light source can
be directed down onto as well as up through an object, so objects that are too thick to
transmit light can still be viewed by reflected light.
Magnification and Field Diameter Size
Examine your stereomicroscope. On the lab worksheet fill in the table 1 using the
techniques and knowledge you applied to the compound microscope.
Introductory Observations
Begin by adjusting your microscope so that it gives the lowest possible magnification.
Place a small piece of newspaper in the center of the stage. Using the focusing knobs,
move the body of the microscope as close to the stage as possible. While looking into
the oculars move the newspaper to the your left. In what direction did the newspaper
appear to move? Now move the newspaper away from you. In what direction does it
appear to move? How do these observations compare to those you recorded when
using the compound microscope? Answer questions 2-5 on your lab worksheet.
DPM IDS Microscope Lab 2 Instructions (page 1)
GREEN RIVER COMMUNITY COLLEGE
IDS Unit 1
Wet Mount Drawings - In-Lab Drawings. (Complete in the lab.)
You will need to supply your own paper for this portion. For each of your drawings
write the name of the type of cell you have drawn. Draw EXACTLY and ONLY
for what is called. Label only those structures indicated. Remember to make
drawings clear and large!!! Present the drawings in the order given below. Drawings
out of order will not be accepted. Staple these to the back of your worksheet.
1. Onion Cell: Drawings One and Two
a. On the inner, concave side of a piece of onion, peel of a small piece of the
epidermis (skin) with forceps. Place this piece (it should be much smaller than
a cover slip) on a slide. Avoid overlapping or wrinkling it. Add 1 or 2 drops of
water and a cover slip.
b. Examine the onion epidermis under low power or your microscope. Look for
cell boundaries. Drawing 1: Draw four-six cells to show the shape and
arrangement of the cells. On this drawing include the following
label: Onion Cells.
c. Place a drop of iodine stain along one edge of the cover slip. Apply a small
piece of dry paper towel or tissue to the opposite side of the cover slip. This will
pull the stain under the cover slip. Note any changes that occur as the stain
spreads across the onion epidermis.
d. Drawing 2: Switch to high power and draw a SINGLE Cell. On this drawing
include the following labels: Onion Cell, Nucleus, Cytoplasm, Cell wall. In
addition estimate the length and width of the cell in micrometers(µm) and add
these to your drawing.
2. Zabrina: Drawing 3
a. Obtain a small piece of a Zabrina leaf. Place it on a slide and observe it under
the scanning or low power of the microscope without using a cover slip or place
it on a slide and observe it under the Stereoscopic microscope.
b. On the lower surface of the leaf observe and draw two guard cells. On this
drawing include the following labels: Zabrina, guard cells (Use your text or
a biology text book for reference pictures.)
3. Human Blood: Drawing 4
a. Obtain a slide of prepared human blood. Under high power, draw One red
blood cell and One white blood cell. On this drawing include the following
labels: red blood cell and label the specific type of white blood cell seen.
See an Anatomy and Physiology or a biology text for a reference.
In addition, estimate the diameter of the red blood cell and include this on
your drawing.
DPM IDS Microscope Lab 2 Instructions (page 2)
GREEN RIVER COMMUNITY COLLEGE
IDS Unit 1
4. Trichonympha: Drawing 5
Trichonympha lives in a symbiotic relationship with termites. These and other
organisms occupy the gut of termites, where they digest wood particles eaten by the
insect. Termites lack the enzymes necessary to digest wood and are dependent on
Trichonympha to make nutrients in the wood available to them. Trichonympha has
become so well adapted to the environment of the termites gut that it cannot survive
outside of it. Thus to examine a specimen, it is first necessary to separate the
Trichonympha from the termite. To obtain a specimen of Trichonympha:
a. Place a drop of insect Ringers solution on a clean microscope slide.
b. Using forceps or your fingers, transfer a termite into the drop of Ringers.
c. Place the slide under the dissecting microscope.
d. Place the tips of dissecting needles at either end of the termite and pull in
opposite directions.
e. Locate the long tube that is the termite’s intestine.
Remove all the larger parts of the insect from the slide.
f. Using a dissecting needle, mash the intestine to release the Trichonympha.
g. Cover your preparation with a clean coverslip.
h. Transfer you slide tot he compound microscope and scan the slide under low
power. Center several Trichonympha in the field of view and then switch to
high power. On this drawing include the following labels: Trichonympha,
Nucleus, Cytoplasm, Cell membrane, Flagella, wood particles.
5. Filamentous algae. Drawing 6
Prepare a wet mount of filamentous algae. Observe with low- and high-power.
Draw ONE or TWO cells on the same paper as your cheek cell. Include the
following labels on your drawing: Algal Cell, cytoplasm, chloroplast, and cell
wall (Use a biology text as a reference.) In addition, estimate the length and width
(in µm) of one of the cells. Record these dimensions on your drawing.
6. Microscopic Animalia organism of your choice: Drawing 7
Prepare a wet mount of pound water. Observe with low- and high-power. Draw
ONE organism of your choice from the Kingdom Animalia. Identify the
organism. Estimate the length and width (or diameter) of this organism in µm.
Record these dimensions on your drawing.
7. Protozoa: Drawings 8-10
Prepare a wet mount from the bottle labeled Protozoa Survey Mixture. Observe
with low-and high-power. Use the dichotomous key to the ‘Protozoan Survey
Mixture’ to key out and draw a protozoan that moves by
a. Flagella - Drawing 8
DPM IDS Microscope Lab 2 Instructions (page 3)
GREEN RIVER COMMUNITY COLLEGE
IDS Unit 1
b. Cilia – Drawing 9
c. Pseudopodia – Drawing 10
Label each drawing with the name of the critter you have keyed out.
8. Cheek cells: Drawing 11
Obtain the following: a clean microscope slide and coverslip, a flat-tipped
toothpick, a bottle of physiologic saline, and a dropper bottle of methylene blue.
a. Place a drop of physiologic saline in the center of the slide. Using the flat end
of the toothpick, gently scrape the inner lining of your cheek. Agitate the end of
the toothpick containing the cheek scrapings in the drop of saline.
b. Add a tiny drop of methylene blue stain to the preparation. Stir again.
Discard the used toothpick in the disposable autoclave bag provided at the
supplies area. Cheek epithelial cells are nearly transparent and thus difficult to
see without the stain, which colors the nuclei of the cells and makes them look
much darker than the cytoplasm.
c. Add a coverslip.
d. Observe under low and then under high power.
e. Draw a SINGLE Cheek cell on a separate sheet of paper. Include the
following labels on your drawing: Cheek Cell, cytoplasm, nucleus, and
plasma membrane (Use a biology text for a reference).
9.
Planaria: Drawing 12
Using a depression slide for the compound microscope prepare a wet mount of a
planaria. Be careful not to leave the critter under the microscope for too long or
you will cook it. Alternatively, you could prepare a small dish for the planaria
and view it under the stereomicroscope. Include the following labels on your
drawing: Planaria. Next to the label ‘Planaria’ include the name of the Phylum
of this critter.
10. Hydra: Drawing 13
Using a depression slide for the compound microscope prepare a wet mount of a
hydra. Be careful not to leave the critter under the microscope for too long or
you will cook it. Alternatively, you could prepare a small dish for the hydra and
view it under the stereomicroscope. Include the following labels on your
drawing: Hydra and tentacle. Next to the label ‘Hydra’ include the name of the
Phylum of this critter.
11. Nematode: Drawing 14
Prepare a wet mount from the material collected from the soil nematode exercise.
Observe with low-and high-power. Draw a representative nematode. Include the
DPM IDS Microscope Lab 2 Instructions (page 4)
GREEN RIVER COMMUNITY COLLEGE
IDS Unit 1
following labels on your drawing: Round worm. Next to the label
‘Roundworm’ include the name of the Phylum of this critter.
DPM IDS Microscope Lab 2 Instructions (page 5)