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  2. Photosynthesis - Wikipedia

    en.wikipedia.org/wiki/Photosynthesis

    To use this stored chemical energy, an organism's cells metabolize the organic compounds through cellular respiration. Photosynthesis plays a critical role in producing and maintaining the oxygen content of the Earth's atmosphere, and it supplies most of the biological energy necessary for complex life on Earth.

  3. Hemoglobin - Wikipedia

    en.wikipedia.org/wiki/Hemoglobin

    In the tetrameric form of normal adult hemoglobin, the binding of oxygen is, thus, a cooperative process. The binding affinity of hemoglobin for oxygen is increased by the oxygen saturation of the molecule, with the first molecules of oxygen bound influencing the shape of the binding sites for the next ones, in a way favorable for binding.

  4. Cellular respiration - Wikipedia

    en.wikipedia.org/wiki/Cellular_respiration

    Cellular respiration. Typical eukaryotic cell. Cellular respiration is the process by which biological fuels are oxidized in the presence of an inorganic electron acceptor, such as oxygen, to drive the bulk production of adenosine triphosphate (ATP), which contains energy. Cellular respiration may be described as a set of metabolic reactions ...

  5. Light-dependent reactions - Wikipedia

    en.wikipedia.org/wiki/Light-dependent_reactions

    Light-dependent reactions are certain photochemical reactions involved in photosynthesis, the main process by which plants acquire energy. There are two light dependent reactions: the first occurs at photosystem II (PSII) and the second occurs at photosystem I (PSI). PSII absorbs a photon to produce a so-called high energy electron which ...

  6. Ecosystem respiration - Wikipedia

    en.wikipedia.org/wiki/Ecosystem_respiration

    Ecosystem respiration is the sum of all respiration occurring by the living organisms in a specific ecosystem. [ 1 ] The two main processes that contribute to ecosystem respiration are photosynthesis and cellular respiration. Photosynthesis uses carbon-dioxide and water, in the presence of sunlight to produce glucose and oxygen whereas cellular ...

  7. Photosystem II - Wikipedia

    en.wikipedia.org/wiki/Photosystem_II

    Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the light-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants, algae, and cyanobacteria. Within the photosystem, enzymes capture photons of light to energize electrons that are then transferred through a variety ...

  8. Photorespiration - Wikipedia

    en.wikipedia.org/wiki/Photorespiration

    Photorespiration (also known as the oxidative photosynthetic carbon cycle or C2 cycle) refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis. The desired reaction is the addition of carbon dioxide to RuBP (carboxylation), a key step in the Calvin–Benson cycle ...

  9. Hill reaction - Wikipedia

    en.wikipedia.org/wiki/Hill_reaction

    The Hill reaction is the light-driven transfer of electrons from water to Hill reagents (non-physiological oxidants) in a direction against the chemical potential gradient as part of photosynthesis. Robin Hill discovered the reaction in 1937. He demonstrated that the process by which plants produce oxygen is separate from the process that ...