Download Observation of a Living Plant Cell

Examining Cells
Investigative Question:
How are plant cells, animal cells and bacterial cells similar to each other? How are they different? What cell
structures can you see with a basic compound microscope?
Hypothesis:
Write an “if….then…..because….” statement for what you would expect to see when you compare plant cells,
animal cells and bacteria cells. You may draw labeled pictures showing what you think you will see if you
prefer.
Procedure:
Rewrite the procedures below in your own words. You make a “labeled diagram” procedure or use complete
sentences.
Part A: Onion cells
1. Place a drop of water on a slide, and place a piece of onion tissue flat in the drop of water. Add a small
drop of iodine stain where your sample is. Cover it with a cover slip.
2. Examine the onion tissue under the low and high powers of the microscope.
3. Make drawings of the onion cells at high power, labeling all of the cell structures you observe. Include
the magnification on your drawing. To find the total magnification, multiply the lens power (written on
the side) by 10 times (the magnification of the eyepiece).
4. Remove the slide from the microscope, and carefully lift up the cover slide and clean the slide.
Part B: Elodea cells
1. Prepare a wet mount of an Elodea leaf.
2. After you have observed the leaf cells under low power, use the fine-adjustment knob to focus slightly
above the cells. You should be able to observe several layers of cells by focusing up and down with the
fine-adjustment knob.
3. Move the slide so that you are able to view the edge of the leaf and locate a spike-shaped cell. This is a
spine cell.
4. Switch to high power and sketch and label this cell and its cell structures.
5. Next move the slide to the interior of the leaf. Locate green, oblong cells. Note the small green
organelles inside each cell. These are the chloroplasts. Sketch and label a few of the cells.
6. Examine the entire leaf to locate chloroplasts that are moving within the cytoplasm. Hint – look along
the vein in the middle of the leaf.
7. Make a sketch of what you see under high power.
Part C: Cheek cells
1. Using the broad end of a flat toothpick, gently scrape the inside of your cheek. Note: The edge of the
toothpick will probably look as though there is nothing on it.
2. Place one drop of water on the second slide. Carefully mix the scrapings in the drop of water. Add a
drop of methylene blue. Be careful not to add more than one small drop. Cover your sample with a
cover slip. Examine the mixture under low and high power.
3. Make drawings of the cheek cells, labeling all structures that you observe. Include the magnification
on your drawing. To find the total magnification, multiply the lens power (written on the side) by 10
times (the magnification of the eyepiece).
Part D: Bacterial Cells
1. Obtain a prepared slide of a variety of bacteria.
2. Locate a cluster of pink bacterial cells under low power. Switch to high power.
3. Sketch a picture of a cell you see and write the total magnification.
Analysis Questions:
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6.
Why did the onion cells not contain green chloroplasts like the elodea?
What is the general shape of the plant cells? The cheek cells? The bacterial cells?
Which parts of the cell stain darker than the other parts?
What differences can you see between plant cells, animal cells and bacterial cells?
Which cells are largest? Which cells are the smallest?
What structures do animal and plant cells have in common? What structures do all cells have in
common?
Conclusion:
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Hypothesis: Answer the investigative question.
Data: What did each type of cell look like? What cell structures did you see in each?
Summary: Summarize what you learned in the lab and whether the purpose was achieved.
Explanation: Explain why you saw differences and similarities between the different cell types.