What is photosynthesis?

During the warmer months, leaves photosynthesize sunlight, producing chlorophyll.

Photosynthesis is a technique for converting sunlight into energy that has been used by certain organisms for about 3.4 billion years. The basic formula involves the conversion of carbon dioxide and water into glucose and oxygen, aided by light-dependent reactions. Photosynthesis arose quickly after the emergence of life itself, thought to have taken place 3.5 billion years ago, after the Earth’s crust cooled. The first photosynthetic organisms were the ancestors of modern cyanobacteria.

Plants use photosynthesis to convert sunlight into energy.

Photosynthesis takes place within chloroplasts, special organelles located in the cells of plants and other photosynthetic organisms. Coloroplasts are green because they use the pigment chlorophyll. The main organs of plants that absorb the sun are the leaves. Although chloroplasts are located in the cells of a plant, chloroplast density is by far the highest in leaves, where between 450,000 and 800,000 chloroplasts can be found in every square millimeter.

Oxygen is one of the by-products of photosynthesis.

Chloroplasts are believed to derive from photosynthetic bacteria, with which they have much in common. Like the power plants of eukaryotic (complex) cells, mitochondria, chloroplasts derive from extremely close symbiotic relationships between early microbes, so close that they became part of the same inseparable entity.

One of the by-products of photosynthesis is oxygen, the molecule that we humans and other animals need to live. Although oxygen today brings life, during a cataclysmic event two billion years ago it brought death. At that 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 consisting of a few tens of millions of years, oxygen-producing photosynthetic cyanobacteria evolved and blanketed the Earth, producing large amounts of oxygen and causing a mass extinction of evolutionary lineages unaccustomed to such high concentrations of atmospheric oxygen. . This is known as the oxygen catastrophe.

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Today, the atmosphere is about 23% oxygen and the rest nitrogen. Plants’ need for oxygen is another reason why we should discourage the destruction of rainforests around the world, especially in the Amazon.

Photosynthetic organisms serve as the basis of every ecosystem. In this role, they are called producers. The organisms that consume them are called consumers.

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