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Energy Flow and Usage in a Food Chain

written by: nanjowe•edited by: Niki Fears•updated: 12/23/2008

The energy that flows through the ecosystem does so through the food chain. Starting off as solar energy and ending up ultimately as heat energy.

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    Importance of Energy Flow

    Energy flow in an ecosystem functions according to Newton’s First Law of thermodynamics “Energy can not be created or destroyed". The energy that flows through the system is converted from one form to another as it travels through the different organisms. Understanding the relationship between this energy flow and the food chain through an ecosystem can lead to a better understanding of how different phenomenon such as global warming or bioaccumulation affects the ecosystem.

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    The Food Chain

    The energy that flows through an ecosystem starts of as Solar Energy which is converted to Chemical Energy. The chemical energy flows through the living ecosystem as the energy rich carbon-carbon bond found in nutrients. Producers like plants, Algae and some bacteria are the group of organisms that create the carbon-carbon bonds. These organisms use photosynthesis to convert solar energy from the sun make the nutrients. This initial capturing of the solar energy has earned them the name; producers. The consumers or heterotrophs feed on producers or autotrophs, consuming the carbon-carbon bond. The heterotrophs through catabolic reactions convert the food into energy that powers their muscles, brains and various other body systems. The heterotrophs in the food chain are divided into trophic (levels) according to what they eat: primary heterotrophs consume plants (herbivores) and secondary heterotrophs consume animals (carnivores). Omnivores consume food from all levels. The food chain is defined as the cyclic flow of nutrients from the producers to highest level of consumers then ultimately back to the producers.

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    Energy Flow in an Ecosystem

    The energy flow in an ecosystem is very similar to the movement of the nutrients in a food chain, with one exception; the energy flows and the food cycles through the system. The solar energy is initially captured by producers that convert carbon dioxide from the atmosphere into oxygen and carbohydrates, creating the energy rich carbon-carbon bond. Primary heterotrophs consume the plants, and in the heterotrophs the energy from the catabolic reactions (breaking the carbon-carbon bond) powers the body and also gives off energy in the form of heat to the ambient surroundings. When primary heterotrophs are consumed by higher level trophic organisms, the energy is transferred in the same way (via the energy rich carbon-carbon bonds). As the animals die their remains are eaten by another group of organisms continuing the energy flow, and while the bodies decompose they give off heat energy. Working beside the natural energy flow exists another energy flow; the man-made energy flow. These are the energy flows that are used to power cars and homes in the human society. This energy flow starts with producers and also ends with the release of carbon dioxide and energy lost as heat, this is the energy flows that include the burning of fossil fuels.

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    Impact on Global Warming

    Global warming is closely related to energy flow. Theoretically the energy that comes into the atmosphere from the sun should equal the energy that flows out of all the energy systems globally; a zero net energy gain. This is not what happens, somehow the amount of solar energy that enters the atmosphere is not jiving with the energy lost to space from the earth. It has been theorized that the increase in emissions in the atmosphere is trapping the heat which is leading to an overall increase in ambient temperatures, hence global warming. The increase in emissions has been attributed to the man-made energy flows. Decreasing this energy flow could decrease emissions and could return the global net energy gain to zero, resulting in a slowing down of the rate of global warming.

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