Name ______________________________ Class ____________ Date ___________
Cells Microscope Lab Part 1- Onion Cells
Background: Allium cepa, the “bulb” onion, is grown underground by the plant as a vertical shoot
that is used for food storage. Onion tissue provides excellent cells to study under the microscope.
The main cell structures are easy to see when viewed with the microscope at medium power. For
example, you will observe a large circular nucleus in each cell, which contains the genetic material
for the cell. Also present in the onion cell is a well-developed cell wall and cell membrane just
beneath it.
Objective: To observe the cells of the skin of an onion. To learn how a compound microscope
works. To learn the proper use of the low and high power objective lenses. To learn the proper use
of the coarse and fine adjustments for focusing.
Materials:
Compound microscope
Skin of an onion (one cell thick)
Dropper with iodine (Note: iodine is toxic and will stain- handle
Slides and cover slips
with care)
Procedure:
Obtain a thin section of skin from an onion bulb. The skin should only be “one cell thick”.
Add 2 drops of iodine to the center of a glass slide. Be careful- iodine can stain your
fingers/clothes. Carefully lay the onion skin flat in the center of the slide on top of the iodine. Do
not fold it over or wrinkle it. Add two drops of iodine to the top of the onion skin.
1 drop iodine
onion skin
1 drop iodine
glass slide
Stand a thin glass cover slip on its edge near the onion skin, next to the drop of iodine.
Slowly lower the other side of the cover slip until it covers the onion skin completely. If there are air
bubbles, gently tap on the glass to “chase” them out. What you have created is called a wet
mount.
cover slip
Verify (check) that your microscope is set to view on the lowest power and that the
microscope light is turned on. Place the slide onto the stage of the microscope and secure it with
the stage clips. Look through the eyepiece and turn the coarse focus knob until an image comes
into focus. Your specimen should look like a brick wall or like lizard skin. Use the fine adjustment
knob to further focus the image as needed. From this point on, you will NOT use the coarse
adjustment knob. Record (draw) what you see on this low power objective in Figure 1. Label these
organelles: cell wall, nucleus, and cytoplasm. You will also need to record the total magnification.
Looking from the side of the microscope, rotate the nosepiece to the medium-powered lens.
If you need to, use the fine adjustment knob to get the image into focus. Do not touch the coarse
adjustment knob. Draw a picture of what you see and record your total magnification in Figure 2.
Label these organelles: cell wall, nucleus, and cytoplasm.
Rotate to the lowest power objective lens and then remove the slide. Clean up by rinsing off
all slides in the sink. Set the cover slips on one paper towel and the slides on another.
Conclusion: Once you have recorded your data, answer the analysis questions for your conclusion
to this lab. You should write good quality answers in complete thoughts and sentences.
Name ______________________________ Class ____________ Date ___________
Cells Microscope Lab Part 1- Onion Cells
Data:
Make sure to label the cell wall, nucleus and cytoplasm in each figure!!!
Figure 1
Figure 2
Total Magnification _________x
Total Magnification _________x
Analysis Questions:
1. Why did we add iodine to our onion cells?
2. Describe the structure of the onion cells. What gives onion cells this rigid shape and
structure?
3. Onions are plants, but yet you don’t see chloroplasts in their cells. Provide a reasonable
hypothesis which explains why this is the case. Hint: read over the background information
regarding where/how onions grow.
4. You should have easily seen a nucleus within each onion cell. Identify the function of this
major eukaryotic organelle.
5. While they weren’t able to be seen using the school’s compound light microscope, onion cells
are full of ribosomes. What is the function of this tiny organelle?
Name ______________________________ Class ____________ Date ___________
Cells Microscope Lab Part 2- Elodea Cells
Background: Waterweed (Elodea canadensis) is a submersed aquarium plant. The highly
magnified view of an elodea leaf shows a living photosynthetic cell. The chloroplasts are found
mostly around the sides of the cell, just inside the cell wall and membrane. This is because most of
the cell is occupied by a water-filled, large central vacuole.
The elodea leaf is composed to two layers of cells. Only one layer of cells is in focus when
using the high power objective. Using a compound microscope, you are limited to only seeing one
layer of cells at a time. Therefore, you must focus up and down using the fine adjustment knob on
the microscope to see both layers of cells.
Objective: To observe the cells of the elodea plant. To identify the major parts of a plant cell. To
learn how a compound microscope works. To learn the proper use of the low and high power
objective lenses. To learn the proper use of the coarse and fine adjustments for focusing.
Materials:
Elodea plant specimen
Compound Microscope
Dropper and Water
Slide and Cover Slip
Procedure:
Remove a young leaf from the tip of a sprig of the elodea plant. Add one drop of water to your
slide. Stand a thin glass cover slip on its edge near the leaf, next to the drop of water. You do no
need a stain to view these cells. Slowly lower the other side of the cover slip until it covers the leaf
completely. If there are any air bubbles underneath the cover slip, gently tap them out. This is
called a wet mount.
cover slip
Verify (check) that the lowest power lens is in place over the stage and the light is on. Place
the slide onto the stage of the microscope and secure it with stage clips. Look through the eyepiece
and turn the coarse focus knob until the image comes into focus. Use the fine adjustment knob to
make the image as clear as possible. From this point on, you will ONLY use the fine adjustment
knob.
Record (draw) what you see on this low power objective in Figure 1. You will also need to
record the total magnification. Label as many of these organelles as you can see: cell wall,
chloroplasts, vacuole, nucleus.
Looking from the side of the microscope, rotate the nosepiece to the medium-powered lens.
If you need to, use the fine focus knob to get the image into focus. Do NOT use the coarse
adjustment knob. Record (draw) what you see on this medium power objective in Figure 2. You
will also need to record the total magnification. Label as many of these organelles as you can see:
cell wall, chloroplasts, vacuole, nucleus.
Looking from the side of the microscope, rotate the nosepiece to the highest powered lens. If
you need to, use the fine focus knob to get the image into focus. Do NOT use the coarse
adjustment knob. If your fine adjustment knob gets “stuck” please ask your teacher for help.
Record (draw) what you see on this high power objective in Figure 3. You will also need to record
the total magnification. Label as many of these organelles as you can see: cell wall, chloroplasts,
vacuole, nucleus. Also, count and record the average number of chloroplasts in each cell.
Rotate to the lowest power objective lens and then remove the slide. Clean up by rinsing off
all slides in the sink. Set the cover slips on one paper towel and the slides on another.
Conclusion: Once you have recorded your data, answer the analysis questions for your conclusion
to this lab. You should write good quality answers in complete thoughts and sentences.
Name ______________________________ Class ____________ Date ___________
Cells Microscope Lab Part 2- Elodea Cells
Data:
Make sure to label the cell wall, chloroplast, vacuole and nucleus in each figure!!!
Figure 1
Total Magnification _________x
Figure 2
Figure 3
Total Magnification _________x
Total Magnification _________x
Analysis Questions:
1. What is the scientific name of elodea? Make sure to write it using the correct format!
2. Describe the structure of the elodea cells. What gives elodea cells this shape and structure?
3. As the slide warmed from the light of the microscope, you should have seen movement
within the elodea cells. What would be moving in an elodea cell? What is the function of
this gel-like, moving substance within the cell?
4. Why do we not stain elodea cells before placing them on the slide?
5. You should have calculated the average number of chloroplasts in each cell. Now estimate
how many cells were in the entire leaf you observed under the microscope, keeping in mind
that the leaf is three cell layers thick. Based on these two estimations, predict how many
chloroplasts would be in one strand of elodea with approximately 60 leaves. SHOW ALL
MATH!
Name ______________________________ Class ____________ Date ___________
Cells Microscope Lab Part 3- Cheek Cells
Background: The cells that line the inside of your cheek are called epithelial cells. They
are constantly being shed like the cells of the outer skin. As a result, some of these cells
can be easily and painlessly removed.
Objective: To observe the cells found in the human cheek. To identify the major parts of
an animal cell. To learn how a compound microscope works. To learn the proper use of the
low and high power objective lenses. To learn the proper use of the coarse and fine
adjustments for focusing.
Materials:
Compound microscope
Slides and cover slips
Dropper and Methylene Blue
Toothpick
Procedure:
Place a drop of methylene blue stain on the center of a clean slide. To collect
epithelial cheek cells gently scrape the inside of one of your cheeks with the flat end of a
toothpick using an up and down motion. You do not have to scrape hard- this should not
be painful!
Transfer your cheek cells by placing the tip of the toothpick into the drop of
methylene blue stain and “mix” by gently swirling. Do not spread the water drop around
the slide. Swirl ten or fifteen times. Adding the stain will allow you to better see the cheek
cells as they are naturally very light in color. Immediately throw this toothpick away.
Stand a thin glass cover slip on its edge next to the drop of water/cells. Slowly lower
the other side of the cover slip until it covers the drop completely. If there are any air
bubbles underneath the cover slip, gently tap them out. This is called a wet mount.
Verify (check) that the lowest power lens is in place over the stage and the light is
on. Place the slide onto the stage of the microscope and secure it with stage clips. Look
through the eyepiece and turn the coarse focus knob until the image comes into focus. Use
the fine adjustment knob to make the image as clear as possible. From this point on, you
will ONLY use the fine adjustment knob.
Record (draw) what you see on this low power objective in Figure 1. You will also
need to record the total magnification. Label as many organelles as you can see, such as
cell membrane and nucleus.
Looking from the side of the microscope, rotate the nosepiece to the mediumpowered lens. If you need to, use the fine focus knob to get the image into focus. Do NOT
use the coarse adjustment knob. Record (draw) what you see on this medium power
objective in Figure 2. You will also need to record the total magnification. Label as many
organelles as you can see, such as cell membrane and nucleus.
Looking from the side of the microscope, rotate the nosepiece to the highest powered
lens. If you need to, use the fine focus knob to get the image into focus. Do NOT use the
coarse adjustment knob. If your fine adjustment knob gets “stuck” please ask your teacher
for help. Record (draw) what you see on this high power objective in Figure 3. You will also
need to record the total magnification. Label as many organelles as you can see, such as
cell membrane and nucleus.
Rotate to the lowest power objective lens and then remove the slide. Do NOT clean
this slide, simply throw it away. It will not be used again.
Conclusion: Once you have recorded your data, answer the analysis questions for your
conclusion to this lab. You should write good quality answers in complete thoughts and
sentences.
Name ______________________________ Class ____________ Date ___________
Cells Microscope Lab Part 3- Cheek Cells
Data:
Make sure to label the cell wall, nucleus and cytoplasm in each figure!!!
Figure 1
Total Magnification _________x
Figure 2
Figure 3
Total Magnification _________x
Total Magnification _________x
Analysis Questions:
1. Why did you add methylene blue stain to your cheek cells?
2. Why do we not see all of the cell’s organelles even when looking through a
microscope?
3. Would you describe cheek cells as having a “regular” or “irregular” shape? Why do
cheek cells have this shape and structure?
4. Describe at least three differences between the plant cells you have observed (onion
and elodea) and the animal cells you have observed (cheek cells).