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Gold Seal Lesson:
Limiting Cell
Size
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Copernicus
Education Gateway
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Subject:
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Science
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Grade:
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9-12
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ICLE Standards:
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Mathematics: Use and value the connections
between mathematics and other disciplines. Use mathematical concepts to
explain real-world phenomena.
Science: Develop an understanding of the cell.
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Performance Task:
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Amy was watching an old science fiction movie
called "The Blob." The movie was about a jelly-like,
protoplasmic, single-celled creature resembling a giant ameba that oozed
and flowed on the other living creatures. These unfortunate plants,
animals, and humans were absorbed and digested by the creature. The more
the creature absorbed, the larger it grew. It grew so large it could cover cities.
Amy understood that his story was fiction, but could not help but wonder
why a single cell could not grow to gigantic sizes like the blob
This activity is designed to help you understand the factors that affect
cell growth. You will explore the relationship between the surface area and
the volume of cells. Since cells are irregularly shaped, making it
difficult to find their surface areas and volumes, we will use cubes to
represent cells in this task. The volume of a cube is given by the formula, and the surface area of a cube is given by the
formula , where e equals
the length of an edge of the cube.
Materials needed: straight edge and
graph paper
- Calculate the surface area and the volume of cubes that have edges whose
measures range consecutively from 1 cm to 8 cm. Record your answers in the
data table below.
- On the same set of axes, draw two line graphs, one for volume and one
for surface area. The x-axis will be labeled with the edge measures of the
cubes and the y-axis will be used for the volume and surface area.
- In your science lab notebook, write a brief analysis of the graphs,
explaining the importance of the point where the lines intersect.
- Find the ratio of the surface area to the volume for each cube and place
your results in the appropriate place in the data table.
- Analyze these ratios and predict what will happen after the 1:1 ratio.
Explain why. Put your explanation in your science lab notebook.
- In your science lab notebook, relate the surface
area: volume ratio to
the two graphs drawn in step 2.
- In your science lab notebook, discuss some of the factors that limit
cell growth.
- In your science lab notebook, explain why there cannot be a giant ameba
that can slither about consuming everything in its path.
Note to the teacher: The purpose of this learning activity is to
demonstrate that the surface area-to-volume ratio of a cell is a factor
that limits its size. Surface area increases at a square rate while volume
increases at a cubic rate. Because the volume increases at a rate greater
than the surface area, the cell must divide or burst. Students should
understand the factors that limit cell growth and size when they have
completed this learning activity
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Knowledge / Skills:
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Plan and apply real or hypothetical models and
constructions to facilitate investigation and learning and the solution to
practical problems. (xs2)
Identify the cell as a common unit between
living things; understand cell structure and the functions they
perform. (s9)
Understand the best procedures for statistical
data collection, organization, and display. (m5)
Understand the use of variables in expressions
such as 4x, x+2, and 2x-1, solve for the variable, and know how to
represent expressions such as "twice the number" or "four
more than the number" using variables. (m7)
Compute the volume of three-dimensional figures
(solids). (m17)
Use the technique of dimensional analysis to
convert units of measure (e.g., convert km/hr to m/min). (m33)
Use writing as a tool for learning in formats
such as learning logs, laboratory reports, note-taking, and journals. (ela40)
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Rubric:
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3 Points =
The student makes a complete response to all parts of the task.
He/she demonstrates a thorough understanding of the factors that limit cell
size. The student uses the appropriate mathematical operations to complete
the task and, through mathematical analysis of the data, is able to
interpret the data table and graphs to understand that cell growth is
limited. Science lab notebook entries are complete, concise, and clearly written.
2 Points = The student makes a complete response to
all parts of the task, but can only realize success with coaching. He/she
demonstrates some understanding of the factors that limit cell size. The
student uses appropriate mathematical operations to complete the task, but
has difficulty interpreting the data table and graphs. He/she demonstrates
only a partial understanding that cell growth is limited. Science lab
notebook entries are fairly complete, but neither concise nor clearly
written.
1 Point = The student is unable to make a complete response to all
parts of the task. He/she has gained little understanding of the factors
that limit cell size and does not understand that cell growth is limited.
The student has difficulty using the geometric formulas for the surface
area and volume of a cube. He/she makes little analysis of the data in the
table and graphs, resulting in no meaningful interpretation. The student's
science lab notebook entries are incomplete, poorly written, and vague.
0 Points = The student makes little effort to
perform the task. His/her work is very incomplete. The student is unable to
make any significant conclusions from his/her sketchy data. Any entry in
the student's science lab notebook, if made, is meaningless.
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Keywords:
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LIFE SCIENCE
CELLS
HUMAN BODY
SCIENTIFIC INQUIRY
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Grades:
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Kg [] - 1 [] - 2 [] - 3 [] - 4 [] - 5 [] - 6 [] - 7 [] - 8 [] - 9 [X]
- 10 [X] - 11 [X] - 12 [X]
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ICLE Application:
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D
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© 2000 International
Center for Leadership in Education
1587 Route 146 - Rexford - NY - 12148
518.399.2776 Fax: 518.399.7607
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