Mystery Cell Lab
INTRODUCTION
Purpose:
Explain the purpose of this lab in 1-2 sentences.
Background:
Briefly discuss cell theory and the “Endosymbiotic” theory.
Hypothesis:
What do you think will be a difference between plant and animal cells?
Variables:
None
Materials:
Compound microscope, microscope slide, cover slips, toothpick, forceps, dropper/pipette, iodine, 4 Mystery
Slides, and Elodea aquarium plant leaf. *WARNING: iodine stains skin and clothing
Procedures:
Part 1: Plant cell
1.
Clean the lenses on your microscope using lens paper only.
2.
Prepare a wet mount of a single Elodea leaf.
3.
Examine the leaf on scanning, center focus and switch to low power.
4.
Center, focus and switch to high power.
5.
Using the fine adjustment knob focus on the layer of cells that have moving chloroplasts.
6.
7.
8.
Draw four or five cells (i.e. don’t fill up a whole circle with squares) and label the following cellular structures:
cell wall, cell membrane (not visible but you should label where it should be), chloroplasts, and cytoplasm.
Answer questions a-f (in complete sentences) in data analysis section of lab.
a. How many cell layers thick is the leaf? *Focus up and down to determine this. You’re approximating so this introduces error.
b. Describe the color and shape of the chloroplast.
c. What is the function of the chloroplasts?
d. In which direction are the chloroplasts moving (if they are moving)?
e. The movement described in question d is called cytoplasmic streaming. What structures are responsible for this movement?
f. Why is it beneficial for the chloroplasts to move rather than remain stationary in the cell?
Return the microscope to scanning power before removing the slide. Dry slide and cover slip for part 2.
Part 2: Animal Cell
1.
Use a clean toothpick to gently scrape the inside of your cheek.
2.
Smear the toothpick with the small piece of cheek tissue on the surface of your microscope slide. Make sure the
smear forms a very thin layer on the surface of the slide.
** You may not see much on the toothpick; however there will be hundreds of cells.
3.
Place one drop of iodine on the top of the smear.
** Remember iodine will stain clothing and skin.
4.
Place a cover slide over the smear as you would with a regular wet mount. Following the proper procedure, examine
the slide under high power.
5.
Draw and label the following structures of the cheek cell: cell membrane, nucleus and cytoplasm.
6.
Answer questions g-j in the data analysis section of your lab report.
g. Why did you use iodine?
h. Why was it important to make the smear thin?
i. Why are cheek cells all different shapes compared to boxes of plant cells?
j. What structure(s) determines the shape of your cheek cell?
Part 3: Mystery Cell
1. Obtain a mystery slide from your teacher and observe it under high power (400X). Be careful when focusing, as, some
of the slides are thick.
2. Use your descriptions and drawings from the plant and animal cell sections of this lab to determine whether your
mystery slide is a plant or animal cell. Record the slide number, descriptions about the mystery cell, and your
identification in the Mystery Cell data table.
3. Repeat steps 1 and 2 for the 3 remaining mystery cells.
4. Did you clean, dry and return all materials? Did you return the microscope to scanning power (4X) before you
removed the slide? Be sure your lab station is clean and dry or you will lose 50% on this lab write-up.
DATA COLLECTION
Drawings and data table should be in this section
Mystery Cell Data Table
Slide Code #
Observations/Descriptions
(should include characteristic of plant or animal cells)
Identification
A
B
C
D
DATA ANALYSIS
Write your answers to questions a-j in complete sentences.
CONCLUSION
Address your Hypothesis: Based on your observations from this lab, not from the textbook, list at least three observable
differences between plant and animal cells.
Error analysis
Suggestions