Energy Transfers Between Organisms

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All living organisms depend on continuous transfers of energy; they require energy to allow certain processes in the body to occur, such as active transport, DNA replication, cell division, protein synthesis, muscle contraction, homeostasis, etc. These are important so that organisms can continue to survive. In this essay, I am going to highlight the way energy is transferred, firstly from the environment to organisms, and the energy transfer between organisms. The main route by which energy enters an ecosystem is photosynthesis. Photosynthesis is the process where light energy is converted into chemical energy in the form of glucose. Its overall equation is: 6CO2 + 6H20 + light energy  C6H12O6 + 6O2. The process of photosynthesis can be split into two reactions: the light-dependent reaction in the thylakoids and the light-independent reaction in the stroma. During the light-dependent reaction, light energy from the Sun is absorbed by chlorophyll (found in the chloroplasts in the leaf). This causes the excitation of two electrons, and they move to a higher energy level. These high-energy electrons move along electron transport chains in a series of redox reactions, releasing energy which activates the enzyme ATPase required in the production of ATP. Reduced NADP (NADPH) is also formed during the light-dependent reaction. The products ATP and reduced NADP from the light-dependent reaction are then used in the light-independent stage of photosynthesis (aka the Calvin cycle). Both ATP and NADPH are responsible for the reduction of glycerate-3-phosphate into triose phosphate, which is converted into many useful organic compounds like carbohydrates, mainly glucose. Although glucose can be used as a direct energy source by plants, it cannot be used directly by animal cells as a source of energy. Instead, cells use ATP as their immediate source of energy. The conversion
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