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Selenium, which is an essential element for animals and prokaryotes and is a beneficial element for many plants, is the least-common of all the elements essential to life. [3] [63] Selenium acts as the catalytic center of several antioxidant enzymes, such as glutathione peroxidase, [11] and plays a wide variety of other biological roles.
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. [2]
Nevertheless, since the production of H 2 is an important loss of energy for the cells, most of nitrogen fixing cyanobacteria also feature at least one uptake hydrogenase. [26] Uptake hydrogenases exhibit a catalytic bias towards oxygen oxidation, thus can assimilate the produced H 2 as a way to recover part of the energy invested during the ...
Phosphorus is most commonly found in the soil in the form of polyprotic phosphoric acid (H 3 PO 4), but is taken up most readily in the form of H 2 PO − 4. Phosphorus is available to plants in limited quantities in most soils because it is released very slowly from insoluble phosphates and is rapidly fixed once again.
Nutrients in the soil are taken up by the plant through its roots, and in particular its root hairs.To be taken up by a plant, a nutrient element must be located near the root surface; however, the supply of nutrients in contact with the root is rapidly depleted within a distance of ca. 2 mm. [14] There are three basic mechanisms whereby nutrient ions dissolved in the soil solution are brought ...
The current process of obtaining hydrogen can emit a lot of carbon dioxide into the atmosphere, but scientists have found a new — greener — way. How seawater can be used to generate valuable ...
The evolution of photosynthesis refers to the origin and subsequent evolution of photosynthesis, the process by which light energy is used to assemble sugars from carbon dioxide and a hydrogen and electron source such as water. It is believed that the pigments used for photosynthesis initially were used for protection from the harmful effects ...
[10] [11] Often this energy is used directly as heat such as in home heaters, which use either petroleum or natural gas. The hydrocarbon is burnt and the heat is used to heat water, which is then circulated. A similar principle is used to create electrical energy in power plants. Both saturated and unsaturated hydrocarbons undergo this process.