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Photosynthesis describes the process by which carbon dioxide and water become glucose and oxygen. This reaction is also known as "oxygen photosynthesis". The sun provides the energy for this process. Oxygen photosynthesis is mainly carried out by plants, but also by cyanobacteria and algae. Only they have the suitable organelles and the necessary pigment chlorophyll to carry out the photosynthesis reaction. Through photosynthesis, dirty air becomes clean again, and in addition you get glucose, a form of energy that is also useful for us. In the microbial world, besides the first mentioned photosynthesis, there is also the anoxygen photosynthesis, where other compounds are used and no oxygen is produced.
Explanation for children:
Plants carry out photosynthesis. This is a reaction in which dirty air becomes clean air again, and on top of that, the plant receives energy so that it can do this again and again. To make photosynthesis, plants need sunlight and water. Therefore, plants must be watered regularly and placed in sunlight. In addition to plants, cyanobacteria and algae can also carry out photosynthesis. These groups have special organelles and pigments that help them to do this. Unfortunately we do not have these organelles, otherwise we could simply stand in the sun to get energy and not need to eat any more.