_____ / 18 A
Name : ____________________
Date : ____________________
_____ / 18 C
OBSERVING CELLS- MICROSCOPY LAB
In this activity you will prepare and examine wet mounts of animal cells and plant cells in order
to observe the structural differences between the two types of cells. A wet mount is used to
observe living cells that are thin and transparent enough for light to pass through. A wet mount
is prepared by placing the specimen on a microscope slide, adding a drop of water and covering
with a cover slip.
You will examine cells of plant and check cells. Since some
cells are colourless, you will need to stain them with a dye to
enhance their visibility.
MATERIALS:
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Laboratory gloves
2 microscope slides
2 cover slips
1 dissecting needles
Forceps
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Paper towels
Compound light microscope
Toothpicks
iodine solution
Small slice of onion
Dropper
Transparent millimeter ruler
PROCEDURE:
PART 1: Examining Cheek Cells (Refer to the diagram below for the procedure)
1. Add one drop of iodine solution to one side of the cover slip.
2. Take a sterile cotton swab and move the swab over the inside of your cheek on one side
of your mouth and along the outer lower side of your gums. (Make sure you are wearing
gloves when swabbing cheek cells)
3. Prepare a wet mount. Lightly spread the swabbed material in the iodine drop solution
placed at the center of the microscope slide.
4. Place a small piece of paper towel at the opposite side of the cover slip as shown in the
figure below. The absorbent paper will draw the die to the other edge of the cover slip,
washing over and staining the cells.
SNC2DP – Mr. Chan
Name : ____________________
Date : ____________________
5. Examine the stained specimen under the microscope.
6. Sketch and label a diagram of two separate check cells on a separate sheet of white
paper. Calculate the total magnification of the image and the estimated cell diameter.
Include all of these values in your drawing and show calculations below. (2 A)
Calculations:
7. Cleaning Procedure: Slides and cover slips should be washed thoroughly, dried and
reused according to your teacher’s instructions.
PART 2: Examining Onion Cells(Refer to the diagram below for the procedure)
1. Place a drop of iodine stain onto a slide
2. Using the tweezers, gently peel the thin layer of tissue off the inside of a small piece
of onion.
3. Gently lower the onion skin onto the slide. Be careful not to crease the skin.
4. Use the tweezers to place a cover slip over the onion skin
5. Examine the stained specimen under the microscope.
SNC2DP – Mr. Chan
Name : ____________________
Date : ____________________
6. Sketch and label a diagram of a section of onion cells on a separate sheet of white
paper. Calculate the total magnification of the image and the estimated cell diameter.
Include all of these values in your drawing and show calculations below. (2 A)
Calculations:
7. Cleaning Procedure: Slides and cover slips should be washed thoroughly, dried and
reused according to your teacher’s instructions.
ANALYSIS QUESTIONS:
Cheek Cells:
1. What is the purpose of adding iodine stain to the cheek cells? (1 A)
2. How did the size, shape& organization of the cheek cell compare to the onion cell? (2 A)
3. Name three organelles that were too small to see in these animal cells using the light
microscope. (3 A)
SNC2DP – Mr. Chan
Name : ____________________
Date : ____________________
Onion Cells:
1. When Robert Hooke looked at cork under a microscope in 1663, he called each of the square
structures a cell because they reminded him of tiny rooms. Do your observations of onion
cells agree with his? Explain why or why not. (2 A)
Applying your Knowledge:
1. Based on your sketches and observations, what are the structures that animal and plant
cells have in common? (3 A)
2. Based on your sketches and observations, what are the structures found only in plant cells?
(1 A)
3.
What other structures can only be found in plant cells that were not visible under the
microscope? (2 A)
SNC2DP – Mr. Chan
Name : ____________________
Date : ____________________
SNC2DP – Mr. Chan
Name : ____________________
Date : ____________________
_____/ 18 C
RUBRIC FOR DRAWING A SPECIMEN
Evaluation Criteria (Communication)
Marking Scheme
Title: underlined, centered, indicates the type
of cell and stained used
0
1
2
Drawing: space is used well, drawn just left of
center on the page, stippling, drawn with a
sharp pencil, not sketched
0
1
2
3
4
Labels: line up on the right side of drawing,
printed and not capitalized, labels point to the
structure being labelled, lines are drawn with
0
a ruler, labels are at the end of the line (not on
top)
1
2
3
4
Other information (bottom right hand
corner): magnification of drawing included,
estimate size of specimen
1
2
3
4
SNC2DP – Mr. Chan
0
5
6
7
8