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Food energy is chemical energy that animals (including humans) derive from their food to sustain their metabolism, including their muscular activity. [ 1 ] Most animals derive most of their energy from aerobic respiration , namely combining the carbohydrates , fats , and proteins with oxygen from air or dissolved in water . [ 2 ]
Chemoorganotrophs are organisms which use the chemical energy in organic compounds as their energy source and obtain electrons or hydrogen from the organic compounds, including sugars (i.e. glucose), fats and proteins. [2] Chemoheterotrophs also obtain the carbon atoms that they need for cellular function from these organic compounds.
The dietary energy supply is the food available for human consumption, usually expressed in kilocalories or kilojoules per person per day. It gives an overestimate of the total amount of food consumed as it reflects both food consumed and food wasted. [1] It varies markedly between different regions and countries of the world.
Gross primary production (GPP) is the amount of chemical energy, typically expressed as carbon biomass, that primary producers create in a given length of time.Some fraction of this fixed energy is used by primary producers for cellular respiration and maintenance of existing tissues (i.e., "growth respiration" and "maintenance respiration").
Other organisms, including halobacteria and flavobacteria [8] and vibrios [9] have purple-rhodopsin-based proton pumps that supplement their energy supply. The archaeal version is called bacteriorhodopsin, while the eubacterial version is called proteorhodopsin. The pump consists of a single protein bound to a Vitamin A derivative, retinal.
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Two low-energy waste products, H 2 O and CO 2, are created during this cycle. [9] [10] The citric acid cycle is an 8-step process involving 18 different enzymes and co-enzymes. During the cycle, acetyl-CoA (2 carbons) + oxaloacetate (4 carbons) yields citrate (6 carbons), which is rearranged to a more reactive form called isocitrate (6 carbons).
[4] [31] The soil is a rich source of bacteria and a few grams contain around a thousand million of them. They are all essential to soil ecology, breaking down toxic waste and recycling nutrients. They are even found in the atmosphere and one cubic metre of air holds around one hundred million bacterial cells.