How do aerobic organisms obtain energy?
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Aerobic respiration requires, of course, oxygen to proceed. After glucose breaks down into two molecules of pyruvate (glycolysis), the pyruvate enters the mitochondria to take part in the citric acid cycle (aka. krebs cycle). The krebs cycle makes energy in the form of ATP, NADH, and FADH2. NADH and FADH2 are high energy electron carriers that make more ATP in the electron transport chain, which happens in the inner mitochondrial membrane and uses oxygen as a final electron acceptor. Thus, you can get about a 36-38 ATP yield from aerobic respiration. Comparatively, anaerobic respiration happens without oxygen and only produces 2 ATP molecules per glucose. This happens through fermentation, which produces lactate/lactic acid in humans (so it's not that great, since it causes sore muscles, etc.). Aerobic respiration produces much more energy than anaerobic repiration does, even though glucose is the starting point for both.
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If you have enough oxygen, your body uses aerobic respiration for its energy needs. Aerobic respiration produces carbon dioxide. Anaerobic respiration is reserved only for when you don't have enough oxygen to do aerobic respiration, which happens after you start to run a bit. Anaerobic respiration does not produce carbon dioxide. However, you also do aerobic respiration at the same time even after running a while, only less because you only have as much oxygen as you keep breathing in. So the answer is running, because aerobic respiration increases when you need the energy.
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All body processes require energy to run properly. When the body is expending more energy than it is taking in (e.g. when exercising), body cells rely on internally stored energy sources, like complex carbohydrates and fats, for energy. The first source the body turns to is glycogen, which is a complex carbohydrate created by the body. When that source is nearly depleted, the body begins lipolysis, the metabolism of fat for energy. In this process, fats, obtained from fat cells, are broken down into glycerol and fatty acids, which can be used to make energy. The primary by-products of metabolism are carbon dioxide and water; carbon dioxide is expelled through the respiratory system.\n\nFats are also secreted by the sebaceous glands (in the skin).
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I pressume you are asking about biomass.\n\nConverting energy from one form to another is never 100% efficient.\nNot all the energy illuminating a plant will be fixed into manufactured organic chemicals (BIOMASS)\nOnly some of the energy available in organic chemicals (food) will be available for animals to build BIOMASS.\n\nAssume 100 units of light energy available, and a 10% energy transfer efficiency, then;\nSun to plant - 10 energy units fixed, and\nPlant to animal - 1 energy unit fixed.\nSo the amount of BIOMASS that could be made decreases dramatically at each trophic level.\n\nALSO - don't forget that some BIOMASS is RESPIRED by the organisms  at each trophic level and is therefore not available to the next level.\n\nNo surprise then that diagrams of biomass for the organisms in an ecosystem look like a pyramid, and that any ecosystem can only support very few top carnivores.
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A) Aerobic respiration\n\nNeurons use an enormous amount of ATP to operate the Na+/K+ pump. Aerobic respiration produces an enormous amount of ATP (36 ATP per 1 glucose). Neurons therefore utilize aerobic respiration.\n\nThe other answers do not make sense. \n\nAnaerobic glycolysis provides very little ATP (2 ATP per 1 glucose). Creatine phosphate provides little ATP and is localized in the muscle. Stored glycogen only directly provides glucose for glycolysis. Catabolism of DNA would lead to the death of the organism, or at least mutagenesis.
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anaerobic respiration produces two ATP(adenosine triphosphate) and then aerobic respiration produces 36 ATP.
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Photosynthesis generally takes light, CO2 & water and makes sugars.  These sugars are chemically converted in to food, propane, methanol, ethanol, coal, oil, wood and all the other fossil fuels and orgnic compounds on the earth, through natural, geologic, and/or manmade processes.  At every step of each process, energy is lost.  To gain usable energy, other than in biologic processes, requires burning something, and using the expansion of heated gases to create physical force (motion), or then using physical force to drive a generator to create electrical current.    \n\nWe do not currently have an effecient method of making electicity using incoming Solar radiation.  Current solar cells convert a small percentage of one section of the electromagnetic spectrum into electric current.\n\nHope this helps.
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released from muscle stores as a form of energy
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a heterotroph obtains energy from food it consumes. This is opposed to an autotroph which obtains energy directly (such as a plant absorbing light energy).
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NADH is produced in organisms in glycolysis and the Krebs cycle (TCA) cycle.  Formation of NAD+ to NADH is reduction.  NADH is produced to create reduction power for the cell.  Some of the reduction power is used in cellular synthesis reactions, but most of the reducing power is brought to the electron transport chain where it is manipulated to create alot of energy in the form of ATP.  Most of the energy created in eukaryotic cells (human, plant, algal, and fungal cells) is created using hte reduction power from NADH to create ATP at the mitochondria.
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The metabolism of most living things involves creating energy or ATP from the catabolism of carbohydrates, primarily monosaccharides.   The primary source of carbohydrates in food comes from the plant kingdom.  Plants use the sun's energy to convert CO2 and H2O into carbohydrates.  So, indirectly the majority of energy produced by all living things originates from the energy of the sun.
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It is grabbed from the CO2 in the air.  Protosynthesis involves combining carbon dioxyde from the air with water to produce sugars and release oxygen.
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In Photosynthesis, plants use the sun's energy as light to transform carbon dioxide and water into glucose.  In cellular respiration,  glucose is ultimately broken down to yield carbon dioxide and water, and the energy from this process is stored as ATP molecules.
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Cells get most of their energy when they break down a glucose molecule in the mitochondrion. This results in the end production of 36 ATP, the energy currency of the cell.
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Basically the body derives energy by stripping electrons off the food you eat and using those electrons to generate a tiny electrical charge to run the tiny electric pumps that keep you alive and moving. Animal cells are essentially just tiny electrochemical motors.\n\nThe catch is that those stripped electrons have to go somewhere, they have to be moved to a lower energy state and disposed of in order to derive that energy. Oxygen is ideal for disposing of electrons because it is extremely electron hungry. It will accept electrons from almost anything. Because of that electron affinity we can take the electrons we strip off food run them down to a very low energy state, sucking almost all the energy from them, and then we can dump them onto oxygen which still accepts them. In comparison other elements are pretty lousy electron acceptors. Once the electrons cease being very high energy those other compounds simply won’t accept them. As a result running anaerobically requires that the electrons be disposed of while they still have a lot of energy in them, so the organism gets less usable energy for each calorie eaten.\n\nYou might compare it to a battery recycler. One place will accept batteries for disposal that are totally dead and another will only accept batteries if they have a few hours life left in them. Obviously the place that will accept the dead batteries will be more efficient to use. Oxygen vs. other electron acceptors is very much like that. Oxygen allows us to suck every last little bit of juice out of our food, other electron acceptors require us to discard the food with quite a bit of potentially usable juice left.
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Respiration happens constantly in many organisms as the main metabolic pathway to provide the cell with ATP (chemical energy).  \n\nThe term respiration also implies that oxygen is needed (this is why your lungs and etc are called the respiratory tract).  Oxygen is the final electron acceptor in the "electron transport chain" of respiration and when it accepts these electrons it forms a water (H2O) molecule\n\nRespiration is coupled with mitochondria in humans and most other eukaryotes.  In humans, mitochondria are used to create a "proton gradient" which drives ATP synthesis in the mitochondria.  Heart cells have many mitochondria for example, and this is because the heart constantly beats and requires energy.  Skeletal Muscle cells also have a decent amount of mitochondria, but when you exercise your muscles and they burn, it is because respiration is going as fast as it can, but since your cells need chemical energy, they have started to use an alternative pathway that produces lactic acid (the burn from exercise).\n\nEven bacteria like e-coli use respiration, though they do not have mitochondria, though often bacteria can live without oxygen and use different metabolic pathways in the absence of oxygen.
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Biological systems have enzymes (and a handful of other reagents) which will use O2 and sugar to make energy--specifically, hexokinase (HK), phosphoglucose isomerase (PGI), phosphofructokinase (PFK), aldolase, triose phosphate isomerase (TIM), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), phosphoglycerate kinase (PGK), phosphoglycerate mutase (PGM), endolase, and pyruvate kinase (PK).  The process undergone is called glycolysis.  The result is that glucose is consumed, making two pyruvate molecules (which in some systems can then enter the Citric Acid Cycle aka Kreb's Cycle) and ADP is turned into ATP, which is an energy source.\n\nAnd after memorizing this and subsequently forgeting all this useless detail some years ago, I nearly ralphed on my book reading this just now.  Bad memories.