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SBI3C
Observing Plant and Animal Cells
Purpose: To observe the organelles of an animal cell and a plant cell and
compare them under a microscope
Procedure for cheek cell
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Put a drop of methylene blue on a slide. Caution: methylene blue will stain
clothes and skin.
Gently scrape the inside of your cheek with the flat side of a toothpick.
Scrape lightly.
Stir the end of the toothpick in the stain and throw the toothpick away.
Place a coverslip on the slide.
Use low power. Cells should be visible, but they will be small and look like
nearly clear purplish blobs. If you are looking at something very dark
purple, it is probably not a cell.
Once you think you have located a cell, switch to high power and refocus.
Draw one or two cheek cells in detail on the highest power. Try and label
nucleus, cytoplasm, and cell membrane
Procedure for onion cell
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Place a drop of water on the slide.
Take a piece of onion from the bowl in the front of the room. Obtain one
layer of epidermal tissue (your teacher will demonstrate this in class).
Place a cover-slip on the slide, slowly lowering it over the sample to avoid
creating air bubbles and then add a small drop of iodine to the slide and
draw it across the onion cell (your teacher will demonstrate this in class).
Use low power. Once you have found an area with several good cells,
switch to high power. Remember to only use the fine adjustment to focus
at higher powers.
Draw one or two onion cells in detail on the highest power. Label the
following: cell membrane, cytoplasm, cell wall, vacuole, nuclear
membrane, nucleus.
Observations: Draw one or two onion/cheek cells in detail on the highest power.
HINT
When drawing objects as seen under a microscope:
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field of view is always a circle
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draw clearly; make distinct lines
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only use pencil
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provide the name of the cell and the power under which it was observed
Analysis
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Why is the use of dyes necessary? What was the purpose of methylene
blue (cheek) and iodine (onion)?
2.
The light microscope used in the lab is not powerful enough to view other
organelles in the cheek cell. What parts of the cell were visible?
3.
List 2 organelles that were NOT visible but should have been in the cheek
cell.
4.
One difference between plant and animal cells is that plant cells contain
chloroplasts. Were any chloroplasts visible in the onion cells? Why or why
not? Explain your reasoning.
In Lab Book
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Purpose
Big Science Concept
Observations (drawing of plant and animal cells)
Analysis (answer questions)