CELL SIZE
Have you ever wondered why cells are so tiny? We are made up of trillions of tiny cells, but why are we not made up of just thousands of larger cells? The reason is because smaller cells function more efficiently than larger cells. This is because smaller cells have more surface area in relation to their volume than larger cells, or in other words, smaller cells have a GREATER surface area to volume ratio than larger cells, and this a good thing!
An example of the relationship seen between cell surface area and volume is seen below:
Cells are not cubic, they are round. Since they are so tiny and fragile it is impossible to find the surface area of a single cell in this class. Cubes are the next best shape to use when determining surface area, and just as effective.
Before we do our lab, we will need to be able to determine surface area and volume in order to get the ratios. Use this guide to determine the surface area and volume of “CUBE A”.
Remember, a cube has six sides!
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Determining the Surface Area of a cube 6l2
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Step one)
Measure one side of the cube to determine the length.
Let us say that the length (l) of cube “A” is 4mm.
Step two)
Square the length to get the surface area of the side you measured l=4 mm
4mm2
Step three)
Since there are 6 sides of a cube, you need to multiply l2 by 6.
6 (4mm)2.
- What is the surface area of cube “A”? ________________
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Determining the Volume of a cube h x l2
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Step one)
Determine the height of your cube (hint: in cubes, h (height) = l (length)
Step two)
Use the length from determining the surface area and plug in the numbers to determine the volume of cube “A”.
4mm x 4mm2
- What is the volume of cube “A”? __________________
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Finding the ratio of surface area and volume
Divide the surface area and volume by the lowest common denominator to get the ratio! |
3. Now find the surface area to volume ratio of a cube in which one side measures 2 mm.
4. If cube “A” and cube “B” were cell “A” and cell “B”, which cell would be more efficient and why?