| Method |
Precise Learning Objective |
Linked |
Question / Activity
(Designed for maximum working out) |
Stepping Stones |
Pitstop Check
(Thinking Map) |
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Water may move across cell membranes via osmosis. |
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What is the name of the process in which water moves across cell membranes? Set up cubes of agar jelly and see how far liquid penetrates them by diffusion over five minutes. Calculate surface area to volume ratio for cubes of different sizes and consider the problems faced by large organisms. |
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A single-celled organism has a relatively large surface area to volume ratio. |
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What is the surface area to volume ratio of a single-celled organism like? |
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Having a large surface area to volume allows sufficient transport of molecules into and out of the cell to meet the needs of the organism. |
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How does having a large surface area to volume ratio help cells? |
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Students should be able to calculate and compare surface area to volume ratios. (MS) |
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How do you calculate surface area to volume ratios? |
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Students should be able to explain the need for exchange surfaces in terms of surface area to volume ratio. |
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Why do simple organisms need exchange surfaces? |
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Students should be able to explain why multicellular organisms have transport systems in terms of surface area to volume ration |
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Why do multicelluar organisms need transport systems? |
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Students should be able to explain how the small intestine and lungs in mammals are adapted for exchanging materials. |
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How are the small intestine and lungs in mammals adapted for exchanging materials? |
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Students should be able to explain how the gills in fish are adapted for exchanging materials. |
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How are the gills in fish are adapted for exchanging materials? |
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Students should be able to explain how the leaves in plants are adapted for exchanging materials. |
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How are leaves in plants adapted for exchanging materials? |
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In multicellular organisms, surfaces and organ systems are specialised for exchanging materials. |
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How are multicellular organisms adapted for exchanging materials? |
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Specalised surfaces allow sufficient molecules to
be transported into and out of cells for the organism?s needs. |
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How do organisms get substances they need in and out of cells? Research adaptations lungs, gills and leaves, describing the chemicals exchanged with directions, adaptations these organs have to carry out the exchange and explain how these adaptations help to maximise the exchange. |
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The effectiveness of an exchange surface is increased by:
? having a large surface area
? a membrane that is thin, to provide a short diffusion path
? (in animals) having an efficient blood supply
? (in animals, for gaseous exchange) being ventilated. |
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How can the effectiveness of an exchange surface be increased? Explain why larger organisms need increasingly more complex exchange surfaces. |
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