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Published byAugust McDowell Modified over 9 years ago
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Starter Activity: On a show me board answer these questions: 1.What does a food chain always start with? 2.What does the arrow in a food chain represent? 3.How much energy is passed on to the next level in a food chain? 4.Give an example of how energy is lost at each stage in a food chain.
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Pyramids of biomass, energy and number. Learning Intention: Show the biomass, energy and numbers of organisms within a food chain as a diagram. Success Criteria: Define ‘Pyramid of biomass’ and construct one from data about a food chain. Define ‘Pyramid of energy’ and construct one from data about a food chain. Define ‘Pyramid of number’ and construct one from data about a food chain.
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Why aren’t food chains very long? This tiger is a top predator; the final level in a food chain. Energy is lost at all levels in food chains. Animals at the top of a long food chain would not get enough energy to survive. Most food chains only contain four or five species, why is this?
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Food chains and pyramids What can pyramids show about energy transfer?
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Pyramids of numbers only give an accurate impression of the flow of energy in a food chain if the organisms are of similar size. Measuring the biomass at each trophic level can give a more accurate picture. Pyramids of numbers are a way of representing food chains. What are the problems of representing food chains in pyramids of numbers? They record the number of organisms at each feeding level in a specified area. What are pyramids of numbers?
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In a pyramid of numbers, the length of each bar represents the number of organisms at each feeding level in a specified area. As a single tree can support many organisms, this food chain produces an irregular pyramid. numbers Understanding pyramids of numbers
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biomass Understanding pyramids of biomass In a pyramid of biomass, the length of each bar represents the volume of organic matter – biomass – at each feeding level in a specified area. At each trophic level, the volume of biomass and energy available is reduced, giving a pyramid shape. The units of measurement is g/m².
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energy Understanding pyramids of energy In a pyramid of energy, the length of each bar represents the volume of energy available– at each feeding level in a specified area. At each trophic level, the volume of biomass and energy available is reduced, giving a pyramid shape. The units of measurement is KJ/m²/year.
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Irregular Pyramids There are some exceptions to the classis pyramid shape. These pyramids are said to be irregular. Some food chains have a single large producer e.g. a tree. Another exception is when a parasite is the top carnivore in the food chain: Fleas Fox Rabbit Lettuce Draw and label the irregular pyramid of numbers for this food chain: Oak tree greenfly ladybird blue tit Irregular pyramid of numbers with a parasite.
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Pyramids Task Draw and label each type of pyramid for each food chain: 1.Oak tree Caterpillar Blackbird Fox 2.Green algae Water flea Tadpole Trout 3.Grass Aphid Ladybird Robin 4. Lettuce Vole Fox Fleas
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Pyramids of biomass, energy and number. Learning Intention: Show the biomass, energy and numbers of organisms within a food chain as a diagram. Success Criteria: Define ‘Pyramid of biomass’ and construct one from data about a food chain. Define ‘Pyramid of energy’ and construct one from data about a food chain. Define ‘Pyramid of number’ and construct one from data about a food chain.
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