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Return to Model Zoom Lesson Plans |
 ZOOMplan
Onion Skins
(ZOOMplan developed by Dr. Vickie Harry, Clarion, Pennsylvania) |
What structures can be observed in onion cells?
The life activities of a cell take place within the cytoplasm. Most
plant cells have similar intercellular organization and most
cellular activities are somewhat similar. The nucleus is the center
of control and regulates cell processes. The DNA, responsible for
passing on features from one generation to another is found in the
nucleus. Other structures of the cell include the cell wall (support
and protection), cell membrane (allows dissolved materials to enter
and leave the cell), vacuole (storage for food and waste), cytoplasm
(where other important cell structures are found), and chloroplasts
(green colored bodies which contain chlorophyll which the plant uses
to make food).
Science: Observational investigation of the structures of onion
cells
Objective: Using DigiScope technology, MAIS elementary and middle
school students will observe an onion cell’s nucleus, cytoplasm,
cell wall, and cell membrane.
Concepts: Structure and function of cellular organization in plants
Processes: Observing, describing, identifying, predicting,
measuring, collecting data, recording data, displaying and
interpreting data
Project AERO Standards: Science: # 1,5, a. Keep records of
investigations and observations and not alter the records.
Science: # 2, 5, c. Know how to make sketches or models to aid
in explaining scientific procedures or ideas. Science: # 4, 5, a.
Use technology, including cameras, tape recorders, and computers, to
store and retrieve verbal and graphic information and data. b. Use a
variety of scientific tools to collect data. Science: # 16, 5, a.
Identify the cell as the fundamental unit of living organisms and
recognize that some organisms are unicellular, while others are
multicellular. Technology: # 1, 5, a. Use keyboards and other
common input and output devices. b. Discuss common uses of
technology in daily life and the advantages and disadvantages those
uses provide. Math: # 2, 3, c. Explain why a prediction,
estimation, or solution is reasonable. Math: # 7, 3, a.
Estimate before measuring to determine the reasonableness of a
solution. b. Estimate and measure length, time, temperature, and
weight to the nearest unit using customary, metric, and nonstandard
measurement. Math: # 10, 3, a. Pose a question and collect
data by observing, measuring, surveying, and counting. English: #
9, 4, b. Gather and record information (e.g., note taking,
photography, surveys). d. Use standard reference tools (e.g.,
dictionary, thesaurus, library information systems, encyclopedia,
on-line information) to gather information for research. Social
Studies: # 8, 5, b. Examine ways in which tools and techniques
make certain tasks easier. d. Describe instances in which changes in
values, beliefs, and attitudes have resulted from new scientific
knowledge and from technological knowledge.
Materials: Raw onion, knife, forceps, slides and cover slips,
Methylene Blue stain solution, droppers and water, paper towels,
DigiScopes
Procedure:
1. After cutting the onion, pull it apart in sections. Using the
forceps, pull off a piece of the thin membrane (skin).
2. Place the skin in the center of the slide and add a drop of
water.
3. Cover the skin with a cover slip, pressing down to remove air
bubbles.
4. View the onion skin at different magnifications to observe the
detail of cellular structure.
5. Remove the eyepiece from the DigiScope and insert the camera in
its place. Now go to the main menu of Motic Play and click the
Capture button. Print the image by clicking on the Jump to Edit
button. When in the editing window, click the Print button. Examine
the printed cells and label their parts.
6. Use a strand of your hair to measure the cells by placing a short
piece of hair across the skin. Predict how many widths of your hair
you could lay side by side over the length of one cell or the width
of one cell.
7. Discuss Robert Hooke’s discovery of cells in 1655.
8. Remove this slide from the microscope and prepare another slide
of onion skin. Stain this specimen with a drop of Methylene Blue.
Repeat step 5.
9. Compare the images of the stained and unstained specimens.
Identify the structures of the onion cell on the captured images.
Students may want to make an illustrated booklet for a PowerPoint
presentation of what they learned.
References:
AIMS Education Foundation. (1995). Magnificent Microworld
Adventures. Fresno, CA: AIMS Education Foundation.
AIMS Education Foundation Newsletter. (1987). Important Things
Come in Small Packages. Fresno, CA: AIMS Education Foundation.
K – 8 Experiment Manual. (2002). Observing the Onion Skin.
Science Kit and Boreal Laboratories & Motic Incorporation Limited. |
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