Download Observing Cells - GoldenBearScience7A

Name: _____________________________________
Date: _________
Per: ______
Observing Cells Lab
/50
What are the similarities and differences between plant and animal cells?
Pre-Lab Questions
Read through the entire lab and then use the lab and your notes or textbook to answer the following
questions. You must have the pre-lab completed before you will be allowed to start the
lab. (1 point each)
1.
What stain, if any, will you use to look at Elodea cells under the microscope? __________________
2. What stain, if any, will you use to look at onion cells under the microscope? ___________________
3. What stain, if any, will you use to look at cheek cells under the microscope? __________________
4. How should you place the Elodea leaf on the slide? ______________________________________
_______________________________________________________________________________
5. What will you use to scrape the inside of your cheek to obtain cheek cells? ___________________
6. What power will you use to draw sketches of the Elodea cell? ______________________________
7. What power will you use to draw sketches of the onion cell? _______________________________
8. What power will you use to draw sketches of the cheek cell? _______________________________
9. State the question that this lab is trying to answer: ________________________________________
_________________________________________________________________________________________
1.
Page 1 of 5
Observing Cells
Problem (Question): How do plant and animal cells differ?
Materials:
microscope
microscope slides
cover slips
forceps
dropper
water
flat toothpick
methylene blue stain
Iodine solution
Elodea leaf
onion peeling
Procedure:
Part I: Elodea Cells
1. Remove a young leaf from the tip of an Elodea plant. Place the leaf so that the under side of
the leaf is facing up when positioned on the slide. Add a drop of water and a cover slip.
2. Place the slide on the microscope stage.
3. Observe the leaf under low power. Slowly turn the fine adjustment of the microscope to see if
there is more than one cell layer in the leaf.
4. Next turn to medium power. Use the course adjustment knob, then the fine adjustment knob
to focus the specimen.
5. Turn to high power. Carefully focus on one cell. Look for any sign of movement in the cell.
6. Write your observations on the data table.
7. Draw the Elodea cell in the first space provided on your Sketch Page and label all parts.
8. Wipe your slide clean and throw away the small piece of Elodea.
Part II: Onion Cells
1. Remove a thin peel of onion and place on the center of a slide. (I will show you how to do this)
2. Put a drop of Iodine solution on the onion, then place the cover slip on top of the onion peel
and drop of iodine.
CAUTION: Iodine can stain skin or clothing. Rinse spills with plenty of water.
3. Observe under low power then carefully switch to medium power and focus.
4. Write your observations in the data table.
5. Draw the onion cells in the space provided on your Sketch Page and label all parts.
6. Wipe your slide clean, taking care not to get any of the Iodine solution on your hands or
clothing.
Part III: Cheek Cells
1. Put a drop of Methylene blue solution on the slide. CAUTION: Methylene blue solution can
stain skin or clothing. Rinse spills with plenty of water.
2. Gently scrape the inside of your cheek with the blunt end of a toothpick. CAUTION: Scrape
lightly. Cells will rub off on the toothpick but you will not be able to see them.
3. Stir the end of the toothpick in the stain. Then throw the toothpick away. CAUTION: Do
not reuse toothpick or leave the toothpick lying around.
4. Place a cover slip on the slide on top of the methylene blue drop (now with cheek cells in it!).
5. Observe the cells under low power and focus. Next switch to medium power and focus.
Finally, switch to high power and focus.
6. Write your observations in the data table.
7. Draw a cheek cell in the space provided on your Sketch Page and label the parts.
8. Remove cover slip and drop slide and cover slip into the container of bleach.
Page 2 of 5
Observing Cells: Data Tables & Questions (1 point for each blank, 2 pts for each
question). ANSWER QUESTIONS USING COMPLETE SENTENCES.
Specimen: ___Elodea Plant Cells_
Type of Stain: _______________________________
Observations: ______________________________________________
___________________________________________________________
Total Magnification Power for sketch: _______________________
Field of View Diameter for power listed above: __________ mm
Estimated number of cells that fit across the FOV: __________
Estimated length of one cell (show work!):
Sketch (2 pts)
1.
= ________mm
Most of the Elodea plant cells have circular green organelles that move, or “stream,” along in the
cytoplasm. What are these organelles called? Why are they important for the plant?
_____________________________________________________________________________________________
_____________________________________________________________________________________________
2. We learned that plants have cell walls and cell membranes. What is the function of the cell wall?
_____________________________________________________________________________________________________
_____________________________________________________________________________________________________
Specimen: ___Onion Bulb Cells____
Type of Stain: _______________________________
Observations: ______________________________________________
___________________________________________________________
Total Magnification Power for sketch: _______________________
Field of View Diameter for power listed above: __________ mm
Estimated number of cells that fit across the FOV: __________
Estimated length of one cell (show work!):
Sketch (2 pts)
Page 3 of 5
= ________mm
3. Elodea leaf cells and onion bulb cells both come from plants. Why do you think the Elodea leaf is
green and the onion bulb is white (before you stained it)? (Hint: Think about where the different
parts of the plant grow)
_____________________________________________________________________________________________
_______________________________________________________________________________
4. Why could you see the nucleus in the onion cell and not in the Elodea cell? (Hint: Think about
what you did differently to get the cells ready for observation).
_____________________________________________________________________________________________
_______________________________________________________________________________
Specimen: ___Human Cheek Cells_(animal cell)___
Type of Stain: _______________________________
Observations: ______________________________________________
___________________________________________________________
Total Magnification Power for sketch: _______________________
Field of View Diameter for power listed above: __________ mm
Estimated number of cells that fit across the FOV: __________
Estimated length of one cell (show work!):
Sketch (2 pts)
= ________mm
5. The human cheek cell is an example of an animal cell. Therefore, which organelles will you
definitely NOT find in this type of cell?
_____________________________________________________________________________________________
_______________________________________________________________________________
6. What is different about the shape of the human cheek cell compared to the other two cells you
observed. Why do you think there is this difference?
_____________________________________________________________________________________________
_______________________________________________________________________________
MORE ON BACK 
Page 4 of 5
Conclusion and Application Question:
Please answer the following questions using complete sentences. (5 points)
7. What are some of the major differences between plants and animals? Which organelles in the cells
are involved in causing this difference? This answer needs to be 3 to 5 sentences in order to be
complete. (Hints: What is different about the way plants and animals obtain their food? What is
different about what plants and animals do to stay alive?)
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
_____________________________________________________________________________________________
Page 5 of 5