Energy flow through ecosystems is a fascinating process that powers...
Biology64 views·Updated 30 Jul 2026·3 pagesEnergy Flow in Ecosystems - Study Notes
Chloé Merson@chlomerson_7
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1
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Energy Transfer in Food Chains
Food chains show how energy moves through an ecosystem across different trophic levels. They typically include producers (like grass), primary consumers (like zebras), secondary consumers (like lions), and sometimes tertiary consumers. The original energy comes from the sun and enters the ecosystem through plants during photosynthesis.
Only about 10% of energy is passed from one trophic level to the next. This means a whopping 90% of energy is lost at each transfer! This energy disappears as heat, gets used for movement, or remains in undigested material like bones and feces.
The small amount of energy that does transfer (that 10%) is used by organisms for important processes like growth, movement, and heat production. This is why there are fewer organisms at higher trophic levels - there simply isn't enough energy to support large populations.
Remember this! The energy passed between organisms is chemical energy used for growth, which is why biomass (the amount of living material) decreases as you move up the food chain.
2
of 3
Pyramids of Numbers and Decomposers
Decomposers play a crucial role in ecosystems by breaking down dead organisms and waste materials. Unlike other consumers, they can be found at all levels of food chains since they feed on the remains from every trophic level.
A pyramid of numbers shows the population size of each species at different trophic levels. While these pyramids often look like actual pyramids (with many producers at the bottom and fewer consumers at the top), some situations create unusual shapes.
For example, in a food chain with an oak tree, caterpillars, shrews, and owls, the pyramid might look inverted at the bottom. This happens because a single large producer (like one oak tree) can support thousands of primary consumers (caterpillars).
Think about it: Pyramids of numbers don't account for organism size, which can sometimes make them misleading. A single large tree provides more energy than several small plants, even though it counts as just "one" in the pyramid.
3
of 3
Pyramid of Energy
Unlike pyramids of numbers, pyramids of energy always form a true pyramid shape. These diagrams show the total energy contained within each population at every trophic level, typically measured in kilojoules (kJ) or kilocalories (kcal).
The pyramid shape is consistent because energy always follows the same pattern in ecosystems: maximum energy at the producer level (bottom) and progressively less energy at each higher level. This reflects the fundamental principle that energy is lost at each transfer.
Energy pyramids give us the most accurate picture of ecosystem structure since they measure what truly limits population sizes - available energy. Even when a single large producer supports many consumers, the energy pyramid still shows the expected decrease at higher levels.
Important concept: Energy pyramids never invert because they represent the fundamental law of energy transfer in ecosystems - you can't have more energy at a higher level than the level below it!
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Biology64 views·Updated 30 Jul 2026·3 pagesEnergy Flow in Ecosystems - Study Notes
Chloé Merson@chlomerson_7
Energy flow through ecosystems is a fascinating process that powers all life on Earth. Starting with the sun, energy travels through food chains, being transferred and transformed at each step, with significant portions being lost along the way.
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of 3
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Energy Transfer in Food Chains
Food chains show how energy moves through an ecosystem across different trophic levels. They typically include producers (like grass), primary consumers (like zebras), secondary consumers (like lions), and sometimes tertiary consumers. The original energy comes from the sun and enters the ecosystem through plants during photosynthesis.
Only about 10% of energy is passed from one trophic level to the next. This means a whopping 90% of energy is lost at each transfer! This energy disappears as heat, gets used for movement, or remains in undigested material like bones and feces.
The small amount of energy that does transfer (that 10%) is used by organisms for important processes like growth, movement, and heat production. This is why there are fewer organisms at higher trophic levels - there simply isn't enough energy to support large populations.
Remember this! The energy passed between organisms is chemical energy used for growth, which is why biomass (the amount of living material) decreases as you move up the food chain.
2
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Pyramids of Numbers and Decomposers
Decomposers play a crucial role in ecosystems by breaking down dead organisms and waste materials. Unlike other consumers, they can be found at all levels of food chains since they feed on the remains from every trophic level.
A pyramid of numbers shows the population size of each species at different trophic levels. While these pyramids often look like actual pyramids (with many producers at the bottom and fewer consumers at the top), some situations create unusual shapes.
For example, in a food chain with an oak tree, caterpillars, shrews, and owls, the pyramid might look inverted at the bottom. This happens because a single large producer (like one oak tree) can support thousands of primary consumers (caterpillars).
Think about it: Pyramids of numbers don't account for organism size, which can sometimes make them misleading. A single large tree provides more energy than several small plants, even though it counts as just "one" in the pyramid.
3
of 3Sign up to see the content. It's free!
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Pyramid of Energy
Unlike pyramids of numbers, pyramids of energy always form a true pyramid shape. These diagrams show the total energy contained within each population at every trophic level, typically measured in kilojoules (kJ) or kilocalories (kcal).
The pyramid shape is consistent because energy always follows the same pattern in ecosystems: maximum energy at the producer level (bottom) and progressively less energy at each higher level. This reflects the fundamental principle that energy is lost at each transfer.
Energy pyramids give us the most accurate picture of ecosystem structure since they measure what truly limits population sizes - available energy. Even when a single large producer supports many consumers, the energy pyramid still shows the expected decrease at higher levels.
Important concept: Energy pyramids never invert because they represent the fundamental law of energy transfer in ecosystems - you can't have more energy at a higher level than the level below it!
We thought you’d never ask...
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