Special subsets of chlorophyll molecules in these photosystems are excited by light energy, allowing electrons on them to be transferred through a series of redox carriers called the electron transfer chain ETC , beginning from the oxygen evolving complex OEC of PSII which oxidizes H 2 O and releases O 2 and protons Diner and Babcock, , through the plastoquinone PQ pool, the cytochrome cyt b 6 f complex Sacksteder et al.
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- What is Photosynthesis?.
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Learn What is Biomimicry? Group Directory Member Directory. Join Sign in. These reactions produce ATP adenosine triphosphate , which provides energy for cellular reactions, and NADP nicotinamide adenine dinucleotide diphosphate , essential in plant metabolism. The entire process can be explained by a single chemical formula. Photosynthesis has several benefits, not just for the photoautotrophs, but also for humans and animals.
The chemical energy stored in plants is transferred to animals and humans when they consume plant matter. It also helps in maintaining a normal level of oxygen and carbon dioxide in the atmosphere. Almost all the oxygen present in the atmosphere can be attributed to this process, which also means that respiration and photosynthesis go together.
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Overview of Photosynthesis
Photosynthesis Process for Kids. Importance of Photosynthesis. Steps of Photosynthesis. Photosynthesis Explained with a Diagram. Photosynthesis in Aquatic Plants. How is Photosynthesis Related to Cellular Respiration. Functions of Chloroplasts. Chloroplast: Structure and Function. Animal Cell Functions. Plant Cell Functions. Pros and Cons of Cloning. Organelles and Their Functions. Requirements for food, materials, and energy in a world where human population is rapidly growing have created a need to increase both the amount of photosynthesis and the efficiency of converting photosynthetic output into products useful to people.
One response to those needs—the so-called Green Revolution , begun in the midth century—achieved enormous improvements in agricultural yield through the use of chemical fertilizers , pest and plant- disease control, plant breeding , and mechanized tilling, harvesting, and crop processing.
Cobalt catalysts allow researchers to duplicate the complicated steps of photosynthesis
This effort limited severe famines to a few areas of the world despite rapid population growth , but it did not eliminate widespread malnutrition. Moreover, beginning in the early s, the rate at which yields of major crops increased began to decline.
This was especially true for rice in Asia. Rising costs associated with sustaining high rates of agricultural production, which required ever-increasing inputs of fertilizers and pesticides and constant development of new plant varieties, also became problematic for farmers in many countries. A second agricultural revolution , based on plant genetic engineering , was forecast to lead to increases in plant productivity and thereby partially alleviate malnutrition.
However, such traits are inherently complex, and the process of making changes to crop plants through genetic engineering has turned out to be more complicated than anticipated. In the future such genetic engineering may result in improvements in the process of photosynthesis, but by the first decades of the 21st century, it had yet to demonstrate that it could dramatically increase crop yields.
Another intriguing area in the study of photosynthesis has been the discovery that certain animals are able to convert light energy into chemical energy. The emerald green sea slug Elysia chlorotica , for example, acquires genes and chloroplasts from Vaucheria litorea , an alga it consumes, giving it a limited ability to produce chlorophyll. When enough chloroplasts are assimilated , the slug may forgo the ingestion of food. The study of photosynthesis began in with observations made by the English clergyman and scientist Joseph Priestley. Priestley had burned a candle in a closed container until the air within the container could no longer support combustion.
He then placed a sprig of mint plant in the container and discovered that after several days the mint had produced some substance later recognized as oxygen that enabled the confined air to again support combustion. He also demonstrated that this process required the presence of the green tissues of the plant. Gas-exchange experiments in showed that the gain in weight of a plant grown in a carefully weighed pot resulted from the uptake of carbon, which came entirely from absorbed carbon dioxide, and water taken up by plant roots; the balance is oxygen, released back to the atmosphere.
Almost half a century passed before the concept of chemical energy had developed sufficiently to permit the discovery in that light energy from the sun is stored as chemical energy in products formed during photosynthesis. In chemical terms, photosynthesis is a light-energized oxidation—reduction process.
- Overview of Photosynthesis | Boundless Biology.
- General characteristics!
Oxidation refers to the removal of electrons from a molecule; reduction refers to the gain of electrons by a molecule. Most of the removed electrons and hydrogen ions ultimately are transferred to carbon dioxide CO 2 , which is reduced to organic products. Other electrons and hydrogen ions are used to reduce nitrate and sulfate to amino and sulfhydryl groups in amino acids , which are the building blocks of proteins.
In most green cells , carbohydrates —especially starch and the sugar sucrose —are the major direct organic products of photosynthesis. The overall reaction in which carbohydrates—represented by the general formula CH 2 O —are formed during plant photosynthesis can be indicated by the following equation:.
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- Overview of Photosynthesis | Boundless Biology.
- The Primary Steps of Photosynthesis.