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Energy Requirements of Living Organisms. Central Concepts. All living organisms require a continuous supply of energy to stay alive. They obtain it either - 1) from the absorption of light energy OR 2) from chemical potential energy. Photosynthesis.
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Energy Requirements of Living Organisms Central Concepts
All living organisms require a continuous supply of energy to stay alive • They obtain it either - 1) from the absorption of light energy OR 2) from chemical potential energy
Photosynthesis • Transfers light energy to chemical potential energy. • Is necessary for the survival of nearly all living organisms (with one or two exceptions). • Supplies organisms with an energy supply and with a useable form of carbon: organic molecules.
Organic compounds • Are those containing carbon as a major constituent, whether natural or artificial. • Organisms which can use an inorganic carbon source (e.g. CO2) are termed autotrophs. • Those which must be provided with ready-made organic carbon are termed heterotrophs.
Organic compounds Can be used in two ways: 1) As building blocks for the production of other organic molecules 2) As a source of chemical potential energy – released when the molecule is broken down during respiration.
Work Takes the form of – • Anabolic reactions: synthesis of large molecules from smaller ones. (Opposites are catabolic reactions). • Active transport • Mechanical work e.g. muscle contraction, movement of cilia & flagella, amoeboid motion, movement of vesicles, etc. • Occasionally, bioluminescence or electrical discharge.
ATP • Structure of adenosine triphosphate: