The two stages of photosynthesis

Bring fact-checked results to the top of your browser search. Basic products of photosynthesis As has been stated, carbohydrates are the most-important direct organic product of photosynthesis in the majority of green plants.

The two stages of photosynthesis

Sugar molecules are produced by the process of photosynthesis in plants and certain bacteria. These organisms lie at the base of the food chain, in that animals and other nonphotosynthesizing organisms depend on them for a constant supply… Energy produced by photosynthesis carried out by plants millions of years ago is responsible for the fossil fuels i.

There, protected from oxidationthese organic remains were slowly converted to fossil fuels. These fuels not only provide much of the energy used in factories, homes, and transportation but also serve as the raw material for plastics and other synthetic products.

Unfortunately, modern civilization is using up in a few centuries the excess of photosynthetic production accumulated over millions of years. Consequently, the carbon dioxide that has been removed from the air to make carbohydrates in photosynthesis over millions of years is being returned at an incredibly rapid rate.

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 Revolutionbegun in the midth century—achieved enormous improvements in agricultural yield through the use of The two stages of photosynthesis fertilizerspest and plant- disease control, plant breedingand mechanized tilling, harvesting, and crop processing.

This effort limited severe famines to a few areas of the world despite rapid population growthbut 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 revolutionbased on plant genetic engineeringwas 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.

The two stages of photosynthesis

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 chloroticafor example, acquires genes and chloroplasts from Vaucheria litorea, an alga it consumes, giving it a limited ability to produce chlorophyll.

When enough chloroplasts are assimilatedthe slug may forgo the ingestion of food. General characteristics Development of the idea 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.

Overall reaction of photosynthesis In chemical terms, photosynthesis is a light-energized oxidation—reduction process. 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 CO2which is reduced to organic products.

Other electrons and hydrogen ions are used to reduce nitrate and sulfate to amino and sulfhydryl groups in amino acidswhich are the building blocks of proteins. In most green cellscarbohydrates —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 CH2O —are formed during plant photosynthesis can be indicated by the following equation: This equation is merely a summary statement, for the process of photosynthesis actually involves numerous reactions catalyzed by enzymes organic catalysts.

These reactions occur in two stages: During the first stage, the energy of light is absorbed and used to drive a series of electron transfers, resulting in the synthesis of ATP and the electron-donor-reduced nicotine adenine dinucleotide phosphate NADPH.

This assimilation of inorganic carbon into organic compounds is called carbon fixation.

In the Calvin cycle, carbon atoms from CO 2 \text {CO}_2 CO 2 C, O, start subscript, 2, end subscript are fixed (incorporated into organic molecules) and used to build three-carbon sugars. This process is fueled by, and dependent on, ATP and NADPH from the light reactions. Unlike the light reactions, which take place in the thylakoid membrane, the reactions of the Calvin cycle take place in. Respiration is the process by which organisms burn food to produce energy. The starting material of cellular respiration is the sugar glucose, which has energy stored in its chemical can think of glucose as a kind of cellular piece of coal: chock-full of energy, . PLANT ENERGY TRANSFORMATIONS 2. Photosynthesis: When life originated on this planet some billion years ago, the first life forms were single celled heterotrophs.

During the 20th century, comparisons between photosynthetic processes in green plants and in certain photosynthetic sulfur bacteria provided important information about the photosynthetic mechanism. Sulfur bacteria use hydrogen sulfide H2S as a source of hydrogen atoms and produce sulfur instead of oxygen during photosynthesis.

The overall reaction is In the s Dutch biologist Cornelis van Niel recognized that the utilization of carbon dioxide to form organic compounds was similar in the two types of photosynthetic organisms. Suggesting that differences existed in the light-dependent stage and in the nature of the compounds used as a source of hydrogen atoms, he proposed that hydrogen was transferred from hydrogen sulfide in bacteria or water in green plants to an unknown acceptor called Awhich was reduced to H2A.Photosynthesis - Basic products of photosynthesis: As has been stated, carbohydrates are the most-important direct organic product of photosynthesis in the majority of green plants.

The formation of a simple carbohydrate, glucose, is indicated by a chemical equation, Little free glucose is produced in plants; instead, glucose units are linked to form starch or are joined with fructose, another. THE PHOTOSYNTHETIC PROCESS In: "Concepts in Photobiology: Photosynthesis and Photomorphogenesis", Edited by GS Singhal, G Renger, SK Sopory, K-D Irrgang and Govindjee, Narosa Publishers/New Delhi; and Kluwer Academic/Dordrecht, pp.

Photosynthesis occurs in two stages. These stages are called the light reactions and the dark reactions. The light reactions take place in the presence of light. The dark reactions do not require direct light, however dark reactions in most plants occur during the day.

Basic products of photosynthesis

The two stages of photosynthesis are light reactions and the Calvin cycle; light reactions take place first, forming the photo portion of photosynthesis, while the Calvin cycle follows, completing the cycle with several steps involving photosynthesis.

Photosynthesis is defined as one process, but.

The two stages of photosynthesis

Photosynthesis occurs in two stages. These stages are called the light reactions and the dark reactions.

Virtual Cell Animation Collection

The light reactions take place in the presence of light. The dark reactions do not require direct light, however dark reactions in most plants occur during the day. No chemical process is more important to life on Earth than photosynthesis —the series of chemical reactions that allow plants to harvest sunlight and create carbohydrate molecules.

Without photosynthesis, not only would there be no plants, the planet could not sustain life of any kind.

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