Download Microscope slides cover slips Methylene blue stain

Name ___________________________________________Date __________ Period _____
Cell Structure and Function Observations (40pt)
Purpose: To observe and examine the differences between plant and animal cells under the
Microscope and investigate the movement of water in a plant cell.
Materials:
Elodea leaves
Onion
Microscope slides
Lugol’s Iodine
Procedure:
CLEAN AND DRY ALL SLIDES AND COVERSLIPS BEFORE USE
-Part One:
water
toothpick
cover slips
20% NaCl
Droppers
microscope
Methylene blue stain
distilled water
Human Cheek Cell:
1. Put a drop of Methylene blue stain in the middle of a clean slide
2. Take a clean toothpick and gently scrape the insides of your cheek with it.
3. Dip and roll the toothpick in the drop of dye on the slide.
NOTE: Cells are microscopic so you will not see anything on the drop. Trust us, the cells
are there and you will be able to see them under the microscope.
4. Discard toothpick and cover the slide with a cover slip
5. Gently blot the slide so excess stain as absorbed
6. Focus the cells under the low power, then switch to high power.
7. Draw one or two cells under the highest power in as much detail as possible
8. Label all identifiable organelles on your drawing along with the correct magnification.
-Part Two: Onion Skin Cell:
1. Separate one layer from an onion quarter and hold it so that the concave (curved inward)
Surface faces you. Snap it backward to separate the transparent paper-thin layer of cells
from the outer curve of the scale.
2. Peel off and tear a small section of the thin layer and lay it flat on the microscope
slide. Trim and smooth any wrinkles.
3. Add one or two drops of Lugol’s Iodine solution and cover with a cover slip.
4. Focus the cells under low power, switch to high power.
5. Draw 2-3 cells attached to each other with as much detail as possible.
6. Label as #8 above (from part one).
-Part Three: Elodea Cells:
1. Prepare a wet mount of the Elodea cells by placing a drop of water on the slide and
then placing one Elodea leaf on it. Pick a young leaf from the tip of the sprig. Make sure
the leaf lies flat and smooth. Cover with a cover slip
2. Observe the cells under low power, and then switch to high.
3. Draw 2-3 cells with as much detail as possible
4. Labels as #8 above (from part one).
Now working at the lab table, make 2 sub lab stations. (A and B)
5. Remove slide from the microscope stage and place on a paper towel.
6. One group(A) from the lab table will add a drop of distilled water and the second group(B)
will add 20% salt solution on one side of the cover slip. Tilt the slide slightly and place a small
piece of paper towel on the other side to pull the water through by capillary action (your teacher
will demonstrate if needed). Leave the slide on the paper towel for about 2-3 minutes. Blot
excess water from the edges of the cover slip and place under the microscope.
7. Draw one or two cells. Label and state magnification.
Clean up (5pt)
Turn revolving nosepiece to the lowest power
Lower the stage all the way
Remove the slide
Clean, Rinse and dry the slides and cover slips and return to your teacher
Turn off microscope; wrap cord around arm, cover
Return to cabinet.
Name ______________________________________________Date ___________ Period___
Cell Structure and Function Observations
Draw, label and state magnification of the cells in the spaces below. (15 points)
Cheek cell
Onion Cell
Elodea (isotonic)
Elodea (hypotonic)
Elodea (hypertonic)
Analysis (14 points)
1. What were some of the differences that you observed in the plant and animal cells?
2. What were the differences between these eukaryotic cells and the prokaryotic cells that you
observed in a previous lab?
3. What were the differences between the two plant cells that you observed?
4. Were you able to locate the vacuole in the plant cell? Explain
5.
What was the effect of the salt solution on the Elodea cell? Why did it happen?
6. What was the effect of the distilled water on the Elodea cell? Why did it happen?
7. Why did the cell in distilled water not explode?
Conclusion/Application (6 points)
1. Why did you not see a chloroplast in the onion cell even though it is a plant cell?
2. Why would your lawn flooded with seawater soon die?