Photosynthesis converts sunlight into energy, producing glucose and oxygen. Chloroplasts, located in cells of photosynthesizing organisms, use chlorophyll to absorb sunlight. Chloroplasts evolved from photosynthetic bacteria through symbiotic relationships. Photosynthesis caused the oxygen catastrophe, leading to mass extinction. Photosynthetic organisms are producers and the foundation of every ecosystem.
Photosynthesis is a technique for converting sunlight into energy that has been used by some organisms for about 3.4 billion years. The basic formula involves a conversion of carbon dioxide and water into glucose and oxygen, aided by light-dependent reactions. Photosynthesis emerged quickly after the emergence of life itself, thought to have occurred 3.5 billion years ago, after the earth’s crust cooled. The first photosynthetic organisms were the ancestors of modern cyanobacteria.
Photosynthesis takes place inside chloroplasts, special organelles located in the cells of plants and other photosynthesizing organisms. Chloroplasts are green because they use the pigment chlorophyll. The main organs of plants that absorb the sun are the leaves. Although chloroplasts are found in cells throughout a plant, chloroplast density is by far the highest on leaves, where between 450,000 and 800,000 chloroplasts can be found in every square millimeter.
Chloroplasts are thought to derive from photosynthetic bacteria, with which they have much in common. As the powerhouses of eukaryotic (complex) cells, mitochondria, chloroplasts are thought to arise from extremely close symbiotic relationships among early microbes, so close as to become part of the same inseparable entity.
One of the byproducts of photosynthesis is oxygen, the molecule we humans and other animals need to live. Although oxygen today brings life, during a catastrophic event two billion years ago, it brought death. At the time, Earth’s atmosphere contained little oxygen, and large iron rocks could be exposed to the surface without rusting. Then, during a geologically sudden period of a few tens of millions of years, oxygen-producing photosynthetic cyanobacteria evolved and blanketed the Earth, producing enormous amounts of oxygen and causing a mass extinction of lineages unaccustomed to concentrations of oxygen. such high atmospheric oxygen. This is known as the oxygen catastrophe.
Today the atmosphere contains about 23% oxygen and the rest nitrogen. The need for oxygen from plants is another reason we should discourage the destruction of rainforests around the world, particularly in the Amazon.
Photosynthetic organisms serve as the foundation of every ecosystem. In this role they are referred to as producers. The organisms that consume them are therefore called consumers.
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