Energy Flow in Ecosystem

Categories: Ecology



Energy is the capacity to do work. There are two form of energy .Potential energy is the energy at rest or also called stored energy which capable of performing work. Kinetic energy is the energy of motion also called free energy.

Laws of Thermodynamics:

  1. The first law of Thermodynamic: It states that amount of energy is constant. Energy can never be created nor be destroyed but it can change from one from to another. E.g Light energy transformed into another type of energy, such as chemical energy or heat energy.

  2. The second law of Thermodynamics: It states that energy like (mechanical, chemical, radiant energy) cannot be changed without some degradation into heat energy. The change of energy from one form to another takes place in such a way that a part of energy assumes waste form (heat energy). After transformation the ability of energy to perform work is decreased energy flows from higher to lower level.

Source of Energy

The Sun main source of energy in ecosystems.

Producers such as plants algae and other use energy from sunlight to make organic matter from Co2 and H2o and then this energy flow in almost all food web. Energy which get from sun then converting it to chemical energy in the form of ATP (photosynthesis) one organism is going to eat to other one and that organism eat an other one all oranisms are dependent on each other directly or indirectly. And all of them are depent on producers through this they get energy.

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Scheme of flow of energy

Trophic level: The producers and consumers in ecosystem can be arranged into several feeding groups, each known as trophic level.

 Food Chains: The set of organisms that pass energy from one trophic level to the next ( all organisms eat at only one trophic level) Grass → mouse → snakes → owls.

Food Webs: A food web recognizes that many organisms eat at multiple trophic levels. Even food webs are interconnected. \nHumans are most important part food webs they are at the top of a food web, since nothing eats them. They are top predators. Organisms that can produce organic molecules are called autotrophs. Organisms that cannot gets energy from abiotic source but depend on energy-rich organic molecules synthesized by autotrophs are called heterotrophs. Those which gets energy from living organisms are called consumers and those which gets energy from dead organisms are called decomposers

 Energy flow is the transfer of energy from the sun and to each subsequent level of the food chain in an environment. Producer produce energy in the form of food and producer require energy to make food which they get from sun(photosynthesis occur ) once the energy is make useable they can respired then energy converted into productivity(GPP NPP) (Photo autotrophs) primary producers, eg plants. Primary consumers gets stored energy in the plant through digestion, and transform it into the form of ATP through respiration. Energy received by primary consumers,( herbivores) is converted to body heat which is radiated away and lost from the system.. Energy loss also occurs in the expulsion of undigested food (Egesta) by excretion Secondary consumers, carnivores, eat the primary consumers omnivores also consume primary producers. Energy which is used primary consumers for growth and storage .Now secondary consumers used that for process of digestion primary and secondary consumers convert this energy into ATP during respiration. Energy which the primary consumers had used for respiration and regulation of body temperature cannot be utilized by the secondary consumers. Tertiary consumers, eat the secondary consumers from them they get some energy and lost some amount of energy . Decomposers which break down the organic matter of the tertiary consumers and release nutrients into the soil. They also break down plants, herbivores and carnivores that were not eaten by organisms higher on the food chain, as well as the undigested food that is excreted by herbivores and carnivores. E.g( Saprotrophicbacteria and fungi) and in this breakdown they provide nitrogen and carbon cycles.

The energy is passed on from trophic level to trophic level and each time about 90% of the energy is lost, with some being lost as heat into the environment (an effect of respiration) and some being lost as incompletely digested food (egesta). Therefore, primary consumers get about 10% of the energy produced by autotrophs, while secondary consumers get 1% and tertiary consumers get 0.1%. This means the top consumer of a food chain receives the least energy, as a lot of the food chain's energy has been lost between trophic levels. . Most of the energy at a trophic level – about 90% – is used at that trophic level. Organisms need it for growth, locomotion, heating themselves, and reproduction. So animals at the second trophic level have only about 10% as much energy available to them as do organisms at the first trophic level. Animals at the third level have only 10% as much available to them as those at the second level.

Pyramid of biomass of organisms: The living weights of the members of the food chain present at any one time form the pyramid of biomass of organisms. Pyramid of energy :Iit describe the amount of total energy which used by the organisms at each trophic level of food chain but also transfer of energy Productivity: The relationship between the amount of energy accumulated and the amount of energy utilized within one trophic level of food chain has an important bearing on how much energy from one trophic level passes on to the next trophic level in the food chain. The ratio of output of energy to input of energy is referred to as ecological efficiency.


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Energy Flow in Ecosystem. (2021, Oct 31). Retrieved from

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