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In actuality, however, plants do not absorb all incoming sunlight (due to reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels) and do not convert all harvested energy into biomass, which results in a maximum overall photosynthetic efficiency of 3 to 6% of total solar radiation. [1]
Plant pigments usually utilize the last two of these reactions to convert the sun's energy into their own. This initial charge separation occurs in less than 10 picoseconds (10 -11 seconds). In their high-energy states, the special pigment and the acceptor could undergo charge recombination; that is, the electron on the acceptor could move back ...
Photosystem II obtains electrons by oxidizing water in a process called photolysis. Molecular oxygen is a byproduct of this process, and it is this reaction that supplies the atmosphere with oxygen. The fact that the oxygen from green plants originated from water was first deduced by the Canadian-born American biochemist Martin David Kamen.
In red algae, the action spectrum is blue-green light, which allows these algae to use the blue end of the spectrum to grow in the deeper waters that filter out the longer wavelengths (red light) used by above-ground green plants. The non-absorbed part of the light spectrum is what gives photosynthetic organisms their color (e.g., green plants ...
The water-splitting reaction occurs on the lumenal side of the thylakoid membrane and is driven by the light energy captured by the photosystems. This oxidation of water conveniently produces the waste product O 2 that is vital for cellular respiration. The molecular oxygen formed by the reaction is released into the atmosphere.
In intense light, plants use various mechanisms to prevent damage to their photosystems. They are able to release some light energy as heat, but the excess light can also produce reactive oxygen species. While some of these can be detoxified by antioxidants, the remaining oxygen species will be detrimental to the photosystems of the plant. More ...
Photosystem II (or water-plastoquinone oxidoreductase) is the first protein complex in the energy-dependent reactions of oxygenic photosynthesis. It is located in the thylakoid membrane of plants , algae , and cyanobacteria .
Chlorophyll, the most abundant plant pigment, is most efficient in capturing red and blue light. Accessory pigments such as carotenes and xanthophylls harvest some green light and pass it on to the photosynthetic process, but enough of the green wavelengths are reflected to give leaves their characteristic color.