Plants receive everything they need for growth and development from the environment. This is how they differ from other living organisms. In order for them to develop well, they need fertile soil, natural or artificial watering and good lighting. Nothing will grow in the dark.

Soil is a source of water and nutritious organic compounds and microelements. But trees, flowers, and grass also need solar energy. It is under the influence of sunlight that certain reactions occur, as a result of which carbon dioxide absorbed from the air is converted into oxygen. This process is called photosynthesis. The chemical reaction that occurs under the influence of sunlight also leads to the formation of glucose and water. These substances are vital for the plant to develop.

In the language of chemists, the reaction looks like this: 6CO2 + 12H2O + light = C6H12O6 + 6O2 + 6H2O. A simplified form of the equation: carbon dioxide + water + light = glucose + oxygen + water.

Literally, “photosynthesis” is translated as “together with light.” This word consists of two simple words “photo” and “synthesis”. The sun is a very powerful source of energy. People use it to generate electricity, insulate houses, and heat water. Plants also need energy from the sun to sustain life. Glucose, produced during photosynthesis, is a simple sugar that is one of the most important nutrients. Plants use it for growth and development, and the excess is deposited in leaves, seeds, and fruits. Not all of the glucose remains unchanged in the green parts of plants and fruits. Simple sugars tend to transform into more complex ones, which include starch. Plants use up such reserves during periods of nutrient shortage. They determine the nutritional value of herbs, fruits, flowers, leaves for animals and people who eat plant foods.

How do plants absorb light?

The process of photosynthesis is quite complex, but it can be described briefly so that it becomes understandable even for school-age children. One of the most common questions concerns the mechanism of light absorption. How does light energy get into plants? The process of photosynthesis occurs in the leaves. The leaves of all plants contain green cells - chloroplasts. They contain a substance called chlorophyll. Chlorophyll is the pigment that gives leaves their green color and is responsible for absorbing light energy. Many people have not thought about why the leaves of most plants are wide and flat. It turns out that nature provided this for a reason. The wide surface allows you to absorb more sunlight. For the same reason, solar panels are made wide and flat.

The upper part of the leaves is protected by a waxy layer (cuticle) from water loss and the adverse effects of weather and pests. It is called palisade. If you look closely at the leaf, you can see that its upper side is brighter and smoother. The rich color is obtained due to the fact that there are more chloroplasts in this part. Excess light can reduce the plant's ability to produce oxygen and glucose. When exposed to bright sun, chlorophyll is damaged and this slows down photosynthesis. A slowdown also occurs with the arrival of autumn, when there is less light, and the leaves begin to turn yellow due to the destruction of chloroplasts in them.

The role of water in photosynthesis and in maintaining plant life cannot be underestimated. Water is needed for:

• providing plants with minerals dissolved in it;
• maintaining tone;
• cooling;
• the possibility of chemical and physical reactions occurring.

Trees, shrubs, and flowers absorb water from the soil with their roots, and then the moisture rises along the stem and passes into the leaves along veins that are visible even to the naked eye.

Carbon dioxide enters through small holes at the bottom of the leaf - stomata. In the lower part of the leaf, the cells are arranged in such a way that carbon dioxide can penetrate more deeply. This also allows the oxygen produced by photosynthesis to easily leave the leaf. Like all living organisms, plants are endowed with the ability to breathe. Moreover, unlike animals and people, they absorb carbon dioxide and release oxygen, and not vice versa. Where there are a lot of plants, the air is very clean and fresh. This is why it is so important to take care of trees and shrubs and create public gardens and parks in large cities.

Light and dark phases of photosynthesis

The process of photosynthesis is complex and consists of two phases - light and dark. The light phase is only possible in the presence of sunlight. When exposed to light, chlorophyll molecules ionize, resulting in energy that serves as a catalyst for chemical reactions. The order of events occurring in this phase is as follows:

• light hits the chlorophyll molecule, which is absorbed by the green pigment and puts it into an excited state;
• water splits;
• ATP is synthesized, which is an energy accumulator.

The dark phase of photosynthesis occurs without the participation of light energy. At this stage, glucose and oxygen are formed. It is important to understand that the formation of glucose and oxygen occurs around the clock, and not just at night. The dark phase is called because the presence of light is no longer necessary for it to occur. The catalyst is ATP, which was synthesized earlier.

The importance of photosynthesis in nature

Photosynthesis is one of the most significant natural processes. It is necessary not only to maintain plant life, but also for all life on the planet. Photosynthesis is needed for:

• providing animals and people with food;
• removing carbon dioxide and saturating the air with oxygen;
• maintaining nutrient cycling.

All plants depend on the rate of photosynthesis. Solar energy can be seen as a factor that promotes or inhibits growth. For example, in the southern regions and areas there is a lot of sun and plants can grow quite tall. If we consider how the process occurs in aquatic ecosystems, there is no shortage of sunlight on the surface of the seas and oceans and abundant algae growth is observed in these layers. In deeper layers of water there is a shortage of solar energy, which affects the growth rate of aquatic flora.

The process of photosynthesis contributes to the formation of the ozone layer in the atmosphere. This is very important as it helps protect all life on the planet from the harmful effects of ultraviolet rays.

Any green leaf is a small factory of oxygen and nutrients necessary for humans and animals for normal life. The process of producing these substances from carbon dioxide and water from the atmosphere is called photosynthesis.

Photosynthesis is a complex process that occurs with the direct participation of light. The very concept of “photosynthesis” comes from two Greek words: “photos” - light and “synthesis” - combination. The process of photosynthesis consists of two stages: the absorption of light quanta and the use of their energy in various chemical reactions. The plant absorbs light with the help of a green substance called chlorophyll. Chlorophyll is found in so-called chloroplasts, which can be found in stems or even fruits. There are especially many of them in, because thanks to its flat structure, the leaf is able to attract more light, and accordingly, receive more energy for photosynthesis. After absorption, chlorophyll passes into and transfers energy to other molecules of the plant organism, in particular those involved in photosynthesis. The second stage of the process takes place without the mandatory participation of light quanta and consists of the formation of chemical bonds with the participation of water and carbon dioxide obtained from the air. At this stage, various substances useful for life, such as starch, are synthesized. These organic substances are used by the plant itself to nourish its various parts and maintain normal life. In addition, these substances are obtained by eating plants, and by people who eat foods of both plant and animal origin. Photosynthesis can occur both under the influence of sunlight and artificial light. In nature, plants, as a rule, “work” intensively in the spring and summer, when there is plenty of sunlight. In autumn, the light becomes less, the days shorten, the leaves turn yellow and fall off. But as soon as the warm spring sun begins to dawn, green foliage appears again and green “factories” begin their work again to provide oxygen, so necessary for life, and other nutrients.

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All living beings need food to survive. Heterotrophic organisms - consumers - use ready-made organic compounds, while autotrophic producers themselves create organic substances in the process of photosynthesis and chemosynthesis. The main producers on Earth are green plants.

It is a sequence of chemical reactions involving photosynthetic pigments, as a result of which organic matter is created from carbon dioxide and water in the light. In the overall equation, six molecules of carbon dioxide combine with six molecules of water to form one molecule, used for energy production and storage. Also, at the end of the reaction, six oxygen molecules are formed as a “by-product”. The process of photosynthesis consists of a light and dark phase. Light quanta excite the electrons of the chlorophyll molecule and transfer them to a higher energy level. Also, with the participation of light rays, photolysis of water occurs - the splitting of a water molecule into hydrogen cations, negatively charged electrons and a free oxygen molecule. The energy stored in the molecular bonds is converted into adenosine triphosphate (ATP) and will be released in the second stage of photosynthesis. In the dark phase, carbon dioxide combines directly with the formation of glucose. A necessary condition for photosynthesis to occur in cells is the green pigment - chlorophyll, so it occurs in green plants and some photosynthetic bacteria. Photosynthetic processes provide the planet with organic biomass, atmospheric oxygen and, as a result, a protective ozone shield. In addition, they reduce the concentration of carbon dioxide in the atmosphere. In addition to photosynthesis, carbon dioxide can be converted into organic matter through chemosynthesis, which differs from the first in the absence of light reactions. Chemosynthetics use light as an energy source, and the energy of redox chemical reactions. For example, nitrifying bacteria oxidize ammonia to nitrous and nitric acid, iron bacteria convert ferrous iron into ferric iron, sulfur bacteria oxidize hydrogen sulfide to sulfur or sulfuric acid. All these reactions release energy, which is subsequently used for the synthesis of organic substances. Only certain types of bacteria are capable of chemosynthesis. Chemosynthetic bacteria do not produce atmospheric oxygen and do not accumulate large amounts of biomass, but they destroy rocks, participate in the formation of minerals and treat wastewater. The biogeochemical role of chemosynthesis is to ensure the cycle of nitrogen, sulfur, iron and other elements in nature.

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Life on Earth is possible thanks to light, mainly solar energy. This energy is converted into the energy of chemical bonds of organic substances formed during photosynthesis.

All plants and some prokaryotes (photosynthetic bacteria and blue-green algae) engage in photosynthesis. Such organisms are called phototrophs . The energy for photosynthesis comes from light, which is captured by special molecules called photosynthetic pigments. Since only a certain wavelength of light is absorbed, some of the light waves are not absorbed but reflected. Depending on the spectral composition of the reflected light, the pigments acquire color - green, yellow, red, etc.

There are three types of photosynthetic pigments - chlorophylls, carotenoids and phycobilins . The most important pigment is chlorophyll. The base is a flat porphyrin core formed by four pyrrole rings connected by methyl bridges, with a magnesium atom in the center. There are various type-a chlorophylls. Higher plants, green and euglena algae have chlorophyll-B, which is formed from chlorophyll-A. Brown and diatom algae contain chlorophyll-C instead of chlorophyll-B, and red algae contain chlorophyll-D. Another group of pigments is formed by carotenoids, which range in color from yellow to red. They are found in all colored plastids (chloroplasts, chromoplasts) of plants. Moreover, in the green parts of plants, chlorophyll masks carotenoids, making them invisible until the onset of cold weather. In autumn, the green pigments are destroyed and carotenoids become clearly visible. Carotenoids are synthesized by phototrophic bacteria and fungi. Phycobilins are present in red algae and cyanobacteria.

Light stage of photosynthesis

Chlorophylls and other pigments in chloroplasts form specific light-harvesting complexes . Using electromagnetic resonance, they transfer the collected energy to special chlorophyll molecules. These molecules, under the influence of excitation energy, give electrons to molecules of other substances - vectors , and then take away electrons from proteins and then from water. The splitting of water during photosynthesis is called photolysis . This occurs in the thylakoid cavities. Protons pass through special channels into the stroma. This releases the energy necessary for ATP synthesis:

2H 2 O = 4e + 4H + + O 2

ADP + P = ATP

The participation of light energy here is a prerequisite, therefore this stage is called the light stage. Oxygen produced as a by-product is removed outside and used by the cell for respiration.

Dark stage of photosynthesis

The following reactions take place in the stroma of the chloroplast. Monosaccharides are formed from carbon dioxide and water. This process itself contradicts the laws of thermodynamics, but since ATP molecules are involved, due to this energy, glucose synthesis is a real process. Later, polysaccharides are created from its molecules - cellulose, starch and other complex organic molecules. The overall equation for photosynthesis can be represented as follows:

6CO 2 + 6H 2 O = C 6 H 12 O 6 + 6O 2

Especially a lot of starch is deposited in chloroplasts during the day during intense photosynthetic processes; at night, starch is broken down into soluble forms and used by the plant.

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DEFINITION: Photosynthesis is the process of formation of organic substances from carbon dioxide and water, in light, with the release of oxygen.

Brief explanation of photosynthesis

The process of photosynthesis involves:

1) chloroplasts,

3) carbon dioxide,

5) temperature.

In higher plants, photosynthesis occurs in chloroplasts - oval-shaped plastids (semi-autonomous organelles) containing the pigment chlorophyll, thanks to the green color of which parts of the plant also have a green color.

In algae, chlorophyll is contained in chromatophores (pigment-containing and light-reflecting cells). Brown and red algae, which live at considerable depths where sunlight does not reach well, have other pigments.

If you look at the food pyramid of all living things, photosynthetic organisms are at the very bottom, among the autotrophs (organisms that synthesize organic substances from inorganic ones). Therefore, they are a source of food for all life on the planet.

During photosynthesis, oxygen is released into the atmosphere. In the upper layers of the atmosphere, ozone is formed from it. The ozone shield protects the Earth's surface from harsh ultraviolet radiation, allowing life to emerge from the sea onto land.

Oxygen is necessary for the respiration of plants and animals. When glucose is oxidized with the participation of oxygen, mitochondria store almost 20 times more energy than without it. This makes the use of food much more efficient, which has led to high metabolic rates in birds and mammals.

A more detailed description of the process of photosynthesis in plants

Progress of photosynthesis:

The process of photosynthesis begins with light hitting chloroplasts - intracellular semi-autonomous organelles containing green pigment. When exposed to light, chloroplasts begin to consume water from the soil, splitting it into hydrogen and oxygen.

Part of the oxygen is released into the atmosphere, the other part goes to oxidative processes in the plant.

Sugar combines with nitrogen, sulfur and phosphorus coming from the soil, in this way green plants produce starch, fats, proteins, vitamins and other complex compounds necessary for their life.

Photosynthesis occurs best under the influence of sunlight, but some plants can be content with artificial lighting.

A complex description of the mechanisms of photosynthesis for the advanced reader

Until the 60s of the 20th century, scientists knew only one mechanism for carbon dioxide fixation - through the C3-pentose phosphate pathway. However, recently a group of Australian scientists was able to prove that in some plants the reduction of carbon dioxide occurs through the C4-dicarboxylic acid cycle.

In plants with a C3 reaction, photosynthesis occurs most actively under conditions of moderate temperature and light, mainly in forests and dark places. Such plants include almost all cultivated plants and most vegetables. They form the basis of the human diet.

In plants with a C4 reaction, photosynthesis occurs most actively under conditions of high temperature and light. Such plants include, for example, corn, sorghum and sugar cane, which grow in warm and tropical climates.

Plant metabolism itself was discovered quite recently, when it was discovered that in some plants that have special tissues for storing water, carbon dioxide accumulates in the form of organic acids and is fixed in carbohydrates only after a day. This mechanism helps plants save water.

How does the process of photosynthesis occur?

The plant absorbs light using a green substance called chlorophyll. Chlorophyll is found in chloroplasts, which are found in stems or fruits. There is a particularly large amount of them in leaves, because due to its very flat structure, the leaf can attract a lot of light, and therefore receive much more energy for the process of photosynthesis.

After absorption, chlorophyll is in an excited state and transfers energy to other molecules of the plant body, especially those that are directly involved in photosynthesis. The second stage of the photosynthesis process takes place without the mandatory participation of light and consists of obtaining a chemical bond with the participation of carbon dioxide obtained from air and water. At this stage, various very useful substances for life, such as starch and glucose, are synthesized.

These organic substances are used by the plants themselves to nourish its various parts, as well as to maintain normal life functions. In addition, these substances are also obtained by animals by eating plants. People also get these substances by eating foods of animal and plant origin.

Conditions for photosynthesis

Photosynthesis can occur both under the influence of artificial light and sunlight. As a rule, plants “work” intensively in nature in the spring and summer, when there is a lot of necessary sunlight. In autumn there is less light, the days are shortened, the leaves first turn yellow and then fall off. But as soon as the warm spring sun appears, green foliage reappears and green “factories” will resume their work again to provide the oxygen so necessary for life, as well as many other nutrients.

Alternative definition of photosynthesis

Photosynthesis (from ancient Greek photo-light and synthesis - connection, folding, binding, synthesis) is the process of converting light energy into the energy of chemical bonds of organic substances in the light by photoautotrophs with the participation of photosynthetic pigments (chlorophyll in plants, bacteriochlorophyll and bacteriorhodopsin in bacteria ). In modern plant physiology, photosynthesis is more often understood as a photoautotrophic function - a set of processes of absorption, transformation and use of the energy of light quanta in various endergonic reactions, including the conversion of carbon dioxide into organic substances.

Phases of photosynthesis

Photosynthesis is a rather complex process and includes two phases: light, which always occurs exclusively in the light, and dark. All processes occur inside the chloroplasts on special small organs - thylakodia. During the light phase, a quantum of light is absorbed by chlorophyll, resulting in the formation of ATP and NADPH molecules. The water then breaks down, forming hydrogen ions and releasing an oxygen molecule. The question arises, what are these incomprehensible mysterious substances: ATP and NADH?

ATP is a special organic molecule found in all living organisms and is often called the “energy” currency. It is these molecules that contain high-energy bonds and are the source of energy in any organic synthesis and chemical processes in the body. Well, NADPH is actually a source of hydrogen, it is used directly in the synthesis of high-molecular organic substances - carbohydrates, which occurs in the second, dark phase of photosynthesis using carbon dioxide.

Light phase of photosynthesis

Chloroplasts contain a lot of chlorophyll molecules, and they all absorb sunlight. At the same time, light is absorbed by other pigments, but they cannot carry out photosynthesis. The process itself occurs only in some chlorophyll molecules, of which there are very few. Other molecules of chlorophyll, carotenoids and other substances form special antenna and light-harvesting complexes (LHC). They, like antennas, absorb light quanta and transmit excitation to special reaction centers or traps. These centers are located in photosystems, of which plants have two: photosystem II and photosystem I. They contain special chlorophyll molecules: respectively, in photosystem II - P680, and in photosystem I - P700. They absorb light of exactly this wavelength (680 and 700 nm).

The diagram makes it more clear how everything looks and happens during the light phase of photosynthesis.

In the figure we see two photosystems with chlorophylls P680 and P700. The figure also shows the carriers through which electron transport occurs.

So: both chlorophyll molecules of two photosystems absorb a light quantum and become excited. The electron e- (red in the figure) moves to a higher energy level.

Excited electrons have very high energy; they break off and enter a special chain of transporters, which is located in the membranes of thylakoids - the internal structures of chloroplasts. The figure shows that from photosystem II from chlorophyll P680 an electron goes to plastoquinone, and from photosystem I from chlorophyll P700 to ferredoxin. In the chlorophyll molecules themselves, in place of electrons after their removal, blue holes with a positive charge are formed. What to do?

To compensate for the lack of an electron, the chlorophyll P680 molecule of photosystem II accepts electrons from water, and hydrogen ions are formed. In addition, it is due to the breakdown of water that oxygen is released into the atmosphere. And the chlorophyll P700 molecule, as can be seen from the figure, makes up for the lack of electrons through a system of carriers from photosystem II.

In general, no matter how difficult it is, this is exactly how the light phase of photosynthesis proceeds; its main essence is the transfer of electrons. You can also see from the figure that in parallel with electron transport, hydrogen ions H+ move through the membrane, and they accumulate inside the thylakoid. Since there are a lot of them there, they move outward with the help of a special conjugating factor, which is orange in the picture, shown on the right and looks like a mushroom.

Finally, we see the final step of electron transport, which results in the formation of the aforementioned NADH compound. And due to the transfer of H+ ions, energy currency is synthesized - ATP (seen on the right in the figure).

So, the light phase of photosynthesis is completed, oxygen is released into the atmosphere, ATP and NADH are formed. What's next? Where is the promised organic matter? And then comes the dark stage, which consists mainly of chemical processes.

Dark phase of photosynthesis

For the dark phase of photosynthesis, carbon dioxide – CO2 – is an essential component. Therefore, the plant must constantly absorb it from the atmosphere. For this purpose, there are special structures on the surface of the leaf - stomata. When they open, CO2 enters the leaf, dissolves in water and reacts with the light phase of photosynthesis.

During the light phase in most plants, CO2 binds to a five-carbon organic compound (which is a chain of five carbon molecules), resulting in the formation of two molecules of a three-carbon compound (3-phosphoglyceric acid). Because The primary result is precisely these three-carbon compounds; plants with this type of photosynthesis are called C3 plants.

Further synthesis in chloroplasts occurs rather complexly. It ultimately forms a six-carbon compound, from which glucose, sucrose or starch can subsequently be synthesized. In the form of these organic substances, the plant accumulates energy. In this case, only a small part of them remains in the leaf, which is used for its needs, while the rest of the carbohydrates travel throughout the plant, arriving where energy is most needed - for example, at the growth points.

The process of photosynthesis ends with dark phase reactions, during which carbohydrates are formed. To carry out these reactions, energy and substances stored during the light phase are used: the Nobel Prize was awarded in 1961 for the discovery of this cycle of reactions. We will try to talk briefly and clearly about the dark phase of photosynthesis.

Localization and conditions

Dark phase reactions take place in the stroma (matrix) of chloroplasts. They do not depend on the presence of light, since the energy they require is already stored in the form of ATP.

For the synthesis of carbohydrates, hydrogen obtained from the photolysis of water and bound in NADPH₂ molecules is used. The presence of sugars is also necessary, to which a carbon atom from the CO₂ molecule will be attached.

The source of sugars for germinating plants is the endosperm - reserve substances that are found in the seed and obtained from the parent plant.

Studying

The set of chemical reactions of the dark phase of photosynthesis leading to the formation of glucose was discovered by M. Calvin and his collaborators.

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Rice. 1. Melvin Calvin in the laboratory.

The first step of the phase is to obtain compounds with three carbon atoms.

For some plants, the first step will be the formation of organic acids with 4 carbon atoms. This path was discovered by Australian scientists M. Hatch and S. Slack and is called C₄ - photosynthesis.

The result of C₄ photosynthesis is also glucose and other sugars.

CO₂ binding

Due to the energy of ATP obtained in the light phase, ribulose phosphate molecules are activated in the stroma. It is converted into the highly reactive compound ribulose diphosphate (RDP), which has 5 carbon atoms.

Rice. 2. Scheme of connecting CO₂ to the RDF.

Two molecules of phosphoglyceric acid (PGA), which has three carbon atoms, are formed. In the next step, PGA reacts with ATP and forms diphosphoglyceric acid. DiPHA reacts with NADPH₂ and is reduced to phosphoglyceraldehyde (PGA).

All reactions occur only under the influence of appropriate enzymes.

PHA forms phosphodioxyacetone.

Hexose formation

At the next stage, by condensation of PHA and phosphodioxyacetone, fructose diphosphate is formed, which contains 6 carbon atoms and is the starting material for the formation of sucrose and polysaccharides.

Rice. 3. Scheme of the dark phase of photosynthesis.

Fructose diphosphate can react with PHA and other dark phase products, giving rise to chains of 4-, 5-, 6-, and 7-carbon sugars. One of the stable products of photosynthesis is ribulose phosphate, which is again included in the reaction cycle, interacting with ATP. To obtain a glucose molecule, it undergoes 6 cycles of dark phase reactions.

Carbohydrates are the main product of photosynthesis, but amino acids, fatty acids, and glycolipids are also formed from intermediate products of the Calvin cycle.

Thus, in the plant body, many functions depend on what happens in the dark phase of photosynthesis. Substances obtained in this phase are used in the biosynthesis of proteins, fats, respiration and other intracellular processes.Evaluation of the report

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27-Feb-2014 | One Comment | Lolita Okolnova

Photosynthesis- the process of formation of organic substances from carbon dioxide and water in the light with the participation of photosynthetic pigments.

Chemosynthesis- a method of autotrophic nutrition in which the source of energy for the synthesis of organic substances from CO 2 is the oxidation reactions of inorganic compounds

Typically, all organisms capable of synthesizing organic substances from inorganic substances, i.e. organisms capable of photosynthesis and chemosynthesis, refer to .

Some are traditionally classified as autotrophs.

We talked briefly about the structure of a plant cell, let's look at the whole process in more detail...

The essence of photosynthesis

(summary equation)

The main substance involved in the multi-stage process of photosynthesis is chlorophyll. It is this that transforms solar energy into chemical energy.

The figure shows a schematic representation of the chlorophyll molecule, by the way, the molecule is very similar to the hemoglobin molecule...

Chlorophyll is built into chloroplast grana:

Light phase of photosynthesis:

(carried out on thylakoid membranes)

• Light hitting a chlorophyll molecule is absorbed by it and brings it into an excited state - the electron that is part of the molecule, having absorbed the energy of light, moves to a higher energy level and participates in synthesis processes;
• Under the influence of light, splitting (photolysis) of water also occurs:

In this case, oxygen is removed into the external environment, and protons accumulate inside the thylakoid in the “proton reservoir”

2Н + + 2е - + NADP → NADPH 2

NADP is a specific substance, a coenzyme, i.e. a catalyst, in this case a hydrogen carrier.

• synthesized (energy)

Dark phase of photosynthesis

(occurs in the stroma of chloroplasts)

actual glucose synthesis

a cycle of reactions occurs in which C 6 H 12 O 6 is formed. These reactions use the energy of ATP and NADPH 2 formed in the light phase; In addition to glucose, other monomers of complex organic compounds are formed during photosynthesis - amino acids, glycerol and fatty acids, nucleotides

Please note: this phase is dark it is called not because it occurs at night - glucose synthesis occurs, in general, around the clock, but the dark phase no longer requires light energy.

“Photosynthesis is a process on which all manifestations of life on our planet ultimately depend.”

K.A. Timiryazev.

As a result of photosynthesis, about 150 billion tons of organic matter are formed on Earth and about 200 billion tons of free oxygen are released per year. In addition, plants involve billions of tons of nitrogen, phosphorus, sulfur, calcium, magnesium, potassium and other elements into the cycle. Although a green leaf uses only 1-2% of the light falling on it, the organic matter created by the plant and oxygen in general.

Chemosynthesis

Chemosynthesis is carried out due to the energy released during chemical oxidation reactions of various inorganic compounds: hydrogen, hydrogen sulfide, ammonia, iron (II) oxide, etc.

According to the substances included in the metabolism of bacteria, there are:

• sulfur bacteria - microorganisms of water bodies containing H 2 S - sources with a very characteristic odor,
• iron bacteria,
• nitrifying bacteria - oxidize ammonia and nitrous acid,
• nitrogen-fixing bacteria - enrich soils, greatly increase productivity,
• hydrogen-oxidizing bacteria

But the essence remains the same - this is also