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Beginning with photosynthesis, water (blue) and carbon dioxide (white) from the air are taken in with solar energy (yellow), and are converted into plant energy (green). [7] 100×10 15 grams of carbon/year fixed by photosynthetic organisms, which is equivalent to 4×10 18 kJ/yr = 4×10 21 J/yr of free energy.
Ecological stoichiometry (more broadly referred to as biological stoichiometry) considers how the balance of energy and elements influences living systems. Similar to chemical stoichiometry, ecological stoichiometry is founded on constraints of mass balance as they apply to organisms and their interactions in ecosystems. [1]
Bioenergetics is a field in biochemistry and cell biology that concerns energy flow through living systems. [1] This is an active area of biological research that includes the study of the transformation of energy in living organisms and the study of thousands of different cellular processes such as cellular respiration and the many other metabolic and enzymatic processes that lead to ...
Biological thermodynamics (Thermodynamics of biological systems) is a science that explains the nature and general laws of thermodynamic processes occurring in living organisms as nonequilibrium thermodynamic systems that convert the energy of the Sun and food into other types of energy. The nonequilibrium thermodynamic state of living ...
Energy intake is measured by the amount of calories consumed from food and fluids. [1] Energy intake is modulated by hunger, which is primarily regulated by the hypothalamus, [1] and choice, which is determined by the sets of brain structures that are responsible for stimulus control (i.e., operant conditioning and classical conditioning) and cognitive control of eating behavior.
The rate of biomass production of an organism is required, which involves measuring growth and reproduction through time. There is still the difficulty of assigning the organisms to a specific trophic level. As well as the organisms in the food chains there is the problem of assigning the decomposers and detritivores to a particular level.
Many plant fibers, for example, are indigestible to many herbivores leaving grazer community food webs more nutrient limited than detrital food webs where bacteria are able to access and release the nutrient and energy stores. [34] [35] "Organisms usually extract energy in the form of carbohydrates, lipids, and proteins. These polymers have a ...
Whether this sort of system is present on Earth is open to debate. However, some relatively simple homeostatic mechanisms are generally accepted. For example, it is sometimes claimed that when atmospheric carbon dioxide levels rise, certain plants may be able to grow better and thus act to remove more carbon dioxide from the atmosphere.