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Copy table into your notebook

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  1. Copy table into your notebook How “Cell” Surface to Volume Ratio affects Rate of Diffusion Xtra line needed

  2. Cell size Limits • The cell must be • large enough to hold materials it needs • small enough to be controlled by the genetic material • ***have large enough surface to volume ratio to allow for efficient exchange of materials with environment at a rate fast enough to sustain life • Most cells are between 10- 20um Nutrients Waste

  3. Each side 1cm x1cm = 1cm2 / side X 6 sides 6cm2

  4. Volume = 1 cm x 1 cm x 1 cm = 1 cm 3 Sfc/vol = 6:1 6:1 6cm2 1 cm 3

  5. Complete chart for other 2 sizes 6cm2 6:1 1 cm 3 24cm2 3:1 8cm 3 28cm2 8cm 3 3.5 : 1 1cm x 2cm x 2 sides = 4cm2 1cm x 4 cm x 2 sides = 8cm2 2cm x 4 cm x 2 sides = 16cm2

  6. In general cells are rarely larger than 20 um. But not always, Can U think of a cell type that can be over a meter long? How could an organism increase its size wo decreasing efficiency?

  7. Surface: volume ratio can be increased by • Altering cell shape: elongating ex. Microvilli, alveolar epithelium

  8. Surface: volume ratio can be increased by • Altering cell shape: elongating , foldsx. Microvilli, alveolar epithelium • Cell ÷  creating more cells w/ same total vol. ex multicellular organism ppt3

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