Mr. Palmé
Biology
Name: ____________________
___________________
As of yet, you have not really had a chance to observe cells and all of the wonders that
they have to offer. Now is your chance. This lab is all about observing cells, the
organelles that they contain, and how they react to various stimuli. Your job is to
create microscope slides of various cell types, observe these slides under the
microscope, and make your observations. Make sure that you follow all of the
directions and answer any questions that you come in contact with along the way.
Work hard. Be thorough. Follow directions.
Part A: Microscope Review
It has been a week since we have had an opportunity to work with the microscopes. We need to make sure
that you remember the proper procedures for using a microscope and preparing wet mount slides.
Finding Your Object:
Before you do anything, here are the helpful hints to almost guarantee you finding the object inside the
microscope.
 move the stage, using the different adjustment knobs, to the highest that it can go
 put the objective lens to the focus power
 open the diaphragm to the opening that allows the most light to pass through the stage
 put the specimen in the center of the diaphragm on the stage
 put the object you are trying to find at the tip of the pointer as seen through the eyepiece
Lab Drawings:
You are going to be asked to do some drawings for each of the cells that you are going to
observe. To do a lab drawing, you want to make it as large as necessary with as much detail
as you can. Follow these directions for each lab drawing.
 there should be two drawings per side of a piece of paper (4 total per page)
o fold the piece of paper horizontally
o draw a large circle that takes up a large portion of each fold
 each drawing should be labeled with a title and the total magnification
Total Magnification:
To figure out total magnification:
 multiply the magnification of the eyepiece by the magnification of the objective that you are
using
Part B: Cork
One of the most important contributions to the foundations of biology was provided by a scientist , Robert
Hooke. Remember, he was the one who helped coin the term “cell.” You are going to observe the same thing
that he observed.
1.
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4.
Obtain a prepared cork slide.
Observe the piece of cork under the microscope at 100x.
Draw five of the cells that you see.
In the drawing, label the cell wall.
Part C: Onion
1. Peel the onion skin from the inner surface of an onion. This is the transparent paper-thin layer of
epidermis, or outer skin, found between the layers of the onion.
2. Place this on a clean slide. Smooth out the wrinkles in the epidermis.
3. Put a drop of iodine on the onion and cover with a coverslip. BE CAREFUL – IODINE STAINS!!!!
4. Observe the onion cells under the microscope at 100x. You should see a lot of boxes lined one on top
of the other and end-to-end. They should appear yellowish in color. In some of those cells you might
notice an orange / brown circle. This is the nucleus.
5. Draw ten of the cells you see. In one of these cells, label the nucleus.
6. Observe the onion cells under the microscope at 400x.
7. Draw three of the cells that you see.
8. In this drawing, label the cell wall.
Part D: Elodea
Elodea is a common flowering plant that lives in freshwater. The green cells of elodea are similar in general
structure and function to those of most other plants. As you are looking at the elodea cells, you will notice that
some cells are packed with small green bodies. These bodies are called chloroplasts.
1. Break off one of the younger leaves near the top of the plant.
2. Place the leaf with its underside up in a drop of water on a clean slide. Put on a coverslip.
3. Focus the elodea leaf under the microscope towards the tip of the leaf at 100x. Draw five of the cells
that you see. Label the cell wall of a cell in this drawing.
4. Focus the elodea leaf under the microscope at 400x.
5. Draw three of the cells that you see.
6. In each drawing, label the chloroplast. These are the little green spheres floating around inside the
cell.
Part E: Cheek
1.
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3.
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9.
Place a drop of iodine on a slide.
Take a toothpick and gently scrape the inner surface of your cheek.
Mix that end of the toothpick in the iodine on the slide.
Put a coverslip on it.
Observe the cheek cells under the microscope at 100x. These are orange “clumps” found floating in
the iodine.
Draw as many cells that you can see in the field of view. Label the cell membrane on one cell.
Focus in on one cell that has an orange dot in the middle. Observe this cheek cell under the
microscope at 400x.
Draw that cell.
In each drawing, label the nucleus in this cell. This is going to be a darker orange ball within the cell.
AFTER YOU OBSERVED EACH OF THE DIFFERENT TYPES OF CELLS,
YOU NEED TO RINSE OFF THE SLIDES THAT YOU USED AND DRY
THEM OFF. PLEASE TRY TO KEEP THE LAB AREA CLEAN.
You are to answer the following questions on a separate piece of paper. The answers must be
typed – you do not need to rewrite the question. Make sure that you and your partner’s name
appear somewhere on all work. I will be collecting all lab drawings and the answers to the
questions found below.
Analysis & Conclusion
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4.
Why were the cork cells empty?
What is the general shape of the onion cell?
Which organelle typically found in plants is not present in the onion?
The part of the onion from which you took cells is usually found below ground. The elodea is found
where sunlight strikes the plant (above ground). What does this suggest about what chloroplasts need
to do their job?
5. Do the cells found in the elodea leaf have the same function as the onion cells you looked at? Why or
why not?
6. Sometimes bubbles are seen on the surface of the elodea leaves. Look up “photosynthesis” in your
text to determine the composition of this gas.
7. Would cells from the rest of your body all look like the cheek cells? Why or why not?
How you will be graded:
 Cork drawing – 3 pts
 Onion drawings – 6 pts
 Elodea drawings – 6 pts
 Cheek drawings – 6 pts
 Answers to ?’s
o 2 pts each = 14 pts
Total Points = 35 points