Exchange Surfaces - Why are Transportation Systems Needed? (GCSE Biology)
Why are Transportation Systems Needed?
Transportation Systems
A transportation system is usually made of a series of connected tubes or vessels to help transport substances from one area of the organism to another. They are usually in close contact with areas and cells where exchange takes place.
Examples of Transportation Systems
- The circulatory system – this transports blood carrying substance including oxygen and glucose and waste materials including urea and carbon dioxide
- The xylem system – this transports water in plants
- The phloem system – this transports sugars in plants
The Need for Transportation Systems
Exchange in an organism depends on its Surface Area to Volume Ratio. Single celled organisms do not have a specific transport. They instead can meet their demands of substances through diffusion.
They are able to do this as they have a large surface area to volume ratio. Therefore, the rate of diffusion is great enough to allow all of the transport through this medium only. As we have grasped, larger, multicellular organisms need to have a specialised system to allow transport.
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