The Relationship Between Cell Size And Diffusion printable pdf download

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Lab. Instructions:

The Relationship Between Cell Size and Diffusion

(staple this sheet to the BACK of your lab report)

GENERAL INFORMATION NEEDED TO WRITE YOUR OWN LAB. REPORT ON YOUR OWN PAPER:

Osmosis and diffusion are important ways cells take in necessary substances. These two processes are also impor-

tant for removing molecules from the cytoplasm. The plasma membrane surrounds the entire cell and forms the

boundary between the cytoplasm on the cell interior and the fluid environment on the outside. Nothing can

diffuse into or out of the cell without crossing the plasma membrane.

Once important substances have crossed the plasma membrane and are inside the cytoplasm, they must be able to

continue diffusing throughout ALL the cytoplasm so life processes can be carried out everywhere in the cell. If

one vital substance or another does not reach a region of the cytoplasm, then injury, disease or even cellular death

may occur. Thus, the ratio of plasma membrane to cytoplasm is the subject of this lab. investigation.

1. Form a mental image of substances moving across the plasma membrane and continuing to diffuse inward

towards the middle of the cytoplasm.

2. You are investigating diffusion in cells that are cube shaped, similar to the cuboidal epithelium in your body.

3. The amount of plasma membrane covering the outside of a cell is called the surface area. The surface area

of a cube is calculated using the formula: surface area = 6 x (length x width), or just: 6 x length

because our

cube shaped cells have six sides. These measurements will be recorded in cm

4. The amount of cytoplasm a cell contains is called the volume. The volume of a cube is calculated using the

formula:

volume = length x width x height, or just: length

. These measurements will be recorded in cm

5. You can study the relationship between the size of a cell and how efficiently diffusion takes place by calculat-

ing the surface area to volume ratio for cells of various sizes. The formula for this is:

Surface area to

surface area

Volume Ratio

volume

(The ratio should be expressed in its simplest form, for example 24:8 is really 3:1.)

The Relationship Between Cell Size And Diffusion