Observing an Onion Cell
Name
Problem/Question: How can I observe the parts of a plant cell?
Hypothesis:
Preparing a wet mount slide of onion skin.
1. Clean the slide and cover slip.
2. Break an onion slice in two. Carefully pull the slice apart.
3. Use tweezers to pull off a very thin piece of the inside part of the onion skin.
4. Place the skin in the center of the slide. (Keep it from folding.) Flatten it as much as possible.
5. Add a drop of water to the onion skin and cover with a coverslip.
6. Press the cover slip down carefully to remove any air bubbles.
7. Place the slide on the microscope stage. Set lens to low power, adjust the focus so the onion
slice is clear.
8. Draw four or five cells in the small circle on your lab sheet.
9. Switch to high power and try to identify the cell wall, cell membrane, nucleus, and cytoplasm.
Data:
40 X
100X
Analyze Data:
Post Lab Discussion questions:
1. What was the general shape of the onion cell?
3. What is the purpose of so many cells close together?
4. Is an onion composed of one cell or many cells
400X
5. All plant cells have cell walls. What is the function of cell walls?
6. Each cell has a control center. What is the control center called? Were you able to see it?
7. Inside the cell wall is a very thin line. It is the cell membrane. What is the purpose of the cell
membrane?
8. Why are onion cells more like squares and rectangles than ovals and circles?
Conclusion:
9. Was your hypothesis correct? Why or why not? What else might you have learned from this
lab?