Photosynthesis is a process like respiration. Photosynthesis and respiration The processes of respiration and photosynthesis. Stage I - preparatory

Every living thing on the planet needs food or energy to survive. Some organisms feed on other creatures, while others can produce their own nutrients. They make their own food, glucose, in a process called photosynthesis.

Photosynthesis and respiration are interconnected. The result of photosynthesis is glucose, which is stored as chemical energy in the body. This stored chemical energy comes from the conversion of inorganic carbon (carbon dioxide) into organic carbon. The process of breathing releases stored chemical energy.

In addition to the products they produce, plants also need carbon, hydrogen, and oxygen to survive. Water absorbed from the soil provides hydrogen and oxygen. During photosynthesis, carbon and water are used to synthesize food. Plants also need nitrates to make amino acids (an amino acid is an ingredient for making protein). In addition to this, they need magnesium to produce chlorophyll.

The note: Living things that depend on other foods are called. Herbivores such as cows, as well as insect-eating plants, are examples of heterotrophs. Living things that produce their own food are called. Green plants and algae are examples of autotrophs.

In this article, you will learn more about how photosynthesis occurs in plants and the conditions necessary for this process.

Definition of photosynthesis

Photosynthesis is the chemical process by which plants, some and algae produce glucose and oxygen from carbon dioxide and water, using only light as an energy source.

This process is extremely important for life on Earth, because it releases oxygen, on which all life depends.

Why do plants need glucose (food)?

Just like humans and other living things, plants also need food to stay alive. The value of glucose for plants is as follows:

• Glucose obtained from photosynthesis is used during respiration to release the energy needed by the plant for other vital processes.
• Plant cells also convert some of the glucose into starch, which is used as needed. For this reason, dead plants are used as biomass because they store chemical energy.
• Glucose is also needed to produce other chemicals such as proteins, fats and plant sugars needed for growth and other essential processes.

Phases of photosynthesis

The process of photosynthesis is divided into two phases: light and dark.

Light phase of photosynthesis

As the name suggests, light phases need sunlight. In light-dependent reactions, the energy of sunlight is absorbed by chlorophyll and converted into stored chemical energy in the form of the electron carrier molecule NADPH (nicotinamide adenine dinucleotide phosphate) and the energy molecule ATP (adenosine triphosphate). Light phases occur in thylakoid membranes within the chloroplast.

Dark phase of photosynthesis or Calvin cycle

In the dark phase or the Calvin cycle, excited electrons from the light phase provide energy for the formation of carbohydrates from carbon dioxide molecules. The light-independent phases are sometimes called the Calvin cycle because of the cyclic nature of the process.

Although the dark phases do not use light as a reactant (and as a result can occur day or night), they require the products of light-dependent reactions to function. The light-independent molecules depend on the energy carrier molecules ATP and NADPH to create new carbohydrate molecules. After the transfer of energy to the molecules, the energy carriers return to the light phases to obtain more energetic electrons. In addition, several dark phase enzymes are activated by light.

Diagram of the phases of photosynthesis

The note: This means that the dark phases will not continue if the plants are deprived of light for too long, as they use the products of the light phases.

The structure of plant leaves

We cannot fully understand photosynthesis without knowing more about leaf structure. The leaf is adapted to play a vital role in the process of photosynthesis.

The external structure of the leaves

• Square

One of the most important features of plants is the large surface area of ​​the leaves. Most green plants are wide, flat and open leaves that are capable of capturing as many solar energy(sunlight) as needed for photosynthesis.

• Central vein and petiole

The midrib and petiole join together and form the base of the leaf. The petiole positions the leaf in such a way that it receives as much light as possible.

• leaf blade

Simple leaves have one leaf blade, while compound leaves have several. The leaf blade is one of the most important components of the leaf, which is directly involved in the process of photosynthesis.

• veins

A network of veins in leaves carries water from the stems to the leaves. The released glucose is also sent to other parts of the plant from the leaves through the veins. In addition, these parts of the leaf support and hold the leaf plate flat for greater sunlight capture. The arrangement of veins (venation) depends on the type of plant.

• leaf base

The base of the leaf is its lowest part, which is articulated with the stem. Often, at the base of the leaf there is a pair of stipules.

• leaf edge

Depending on the type of plant, the leaf edge may have various shapes, including: entire, serrated, serrate, notched, crenate, etc.

• Leaf tip

Like the edge of the sheet, the top is various shapes, including: sharp, round, blunt, elongated, retracted, etc.

The internal structure of the leaves

Below is a close diagram of the internal structure of leaf tissues:

• Cuticle

The cuticle acts as the main, protective layer on the surface of the plant. As a rule, it is thicker on the top of the sheet. The cuticle is covered with a wax-like substance that protects the plant from water.

• Epidermis

The epidermis is a layer of cells that is the integumentary tissue of the leaf. Its main function is to protect the internal tissues of the leaf from dehydration, mechanical damage and infections. It also regulates the process of gas exchange and transpiration.

• Mesophyll

The mesophyll is the main tissue of the plant. This is where the process of photosynthesis takes place. In most plants, the mesophyll is divided into two layers: the upper one is palisade and the lower one is spongy.

• Protective cells

Guard cells are specialized cells in the leaf epidermis that are used to control gas exchange. They perform protective function for the stomata. The stomatal pores become large when water is freely available, otherwise the protective cells become lethargic.

• Stoma

Photosynthesis depends on the penetration of carbon dioxide (CO2) from the air through the stomata into the mesophyll tissues. Oxygen (O2), obtained as a by-product of photosynthesis, exits the plant through the stomata. When the stomata are open, water is lost through evaporation and must be replenished through the flow of transpiration by water taken up by the roots. Plants are forced to balance the amount of CO2 absorbed from the air and the loss of water through the stomatal pores.

Conditions required for photosynthesis

The following are the conditions that plants need to carry out the process of photosynthesis:

• Carbon dioxide. A colorless, odorless natural gas found in the air and has the scientific designation CO2. It is formed during the combustion of carbon and organic compounds, and also occurs during respiration.
• Water. Transparent liquid chemical, odorless and tasteless (under normal conditions).
• Light. Although artificial light is also suitable for plants, natural sunlight generally creates the best conditions for photosynthesis because it contains natural ultraviolet radiation, which has a positive effect on plants.
• Chlorophyll. It is a green pigment found in the leaves of plants.
• Nutrients and minerals. Chemicals and organic compounds that plant roots absorb from the soil.

What is formed as a result of photosynthesis?

• Glucose;
• Oxygen.

(Light energy is shown in parentheses because it is not a substance)

The note: Plants take in CO2 from the air through their leaves, and water from the soil through their roots. Light energy comes from the Sun. The resulting oxygen is released into the air from the leaves. The resulting glucose can be converted into other substances, such as starch, which is used as an energy store.

If the factors that promote photosynthesis are absent or present in insufficient quantities, this can negatively affect the plant. For example, less light creates favorable conditions for insects that eat the leaves of a plant, while a lack of water slows it down.

Where does photosynthesis take place?

Photosynthesis takes place inside plant cells, in small plastids called chloroplasts. Chloroplasts (mostly found in the mesophyll layer) contain a green substance called chlorophyll. Below are other parts of the cell that work with the chloroplast to carry out photosynthesis.

The structure of a plant cell

Functions of plant cell parts

• : provides structural and mechanical support, protects cells from bacteria, fixes and defines the shape of the cell, controls the rate and direction of growth, and gives shape to plants.
• : provides a platform for most of the chemical processes controlled by enzymes.
• : acts as a barrier, controlling the movement of substances into and out of the cell.
• : as described above, they contain chlorophyll, a green substance that absorbs light energy during photosynthesis.
• : a cavity within the cell cytoplasm that stores water.
• : contains a genetic mark (DNA) that controls the activity of the cell.

Chlorophyll absorbs the light energy needed for photosynthesis. It is important to note that not all color wavelengths of light are absorbed. Plants mainly absorb red and blue wavelengths - they do not absorb light in the green range.

Carbon dioxide during photosynthesis

Plants take in carbon dioxide from the air through their leaves. Carbon dioxide seeps through a small hole at the bottom of the leaf - the stomata.

The underside of the leaf has loosely spaced cells to allow carbon dioxide to reach other cells in the leaf. It also allows the oxygen produced by photosynthesis to easily leave the leaf.

Carbon dioxide is present in the air we breathe in very low concentrations and is a necessary factor in the dark phase of photosynthesis.

Light in the process of photosynthesis

The sheet usually has a large surface area, so it can absorb a lot of light. Its upper surface is protected from water loss, disease and weather by a waxy layer (cuticle). The top of the sheet is where the light falls. This layer of mesophyll is called the palisade. It is adapted to absorb a large number light, because it contains a lot of chloroplasts.

In the light phases, the process of photosynthesis increases with more light. More chlorophyll molecules are ionized and more ATP and NADPH are generated if light photons are focused on a green leaf. Although light is extremely important in the light phases, it should be noted that too much of it can damage chlorophyll and reduce the process of photosynthesis.

Light phases are not too dependent on temperature, water or carbon dioxide, although they are all needed to complete the photosynthesis process.

Water during photosynthesis

Plants get the water they need for photosynthesis through their roots. They have root hairs that grow in the soil. The roots are characterized by a large surface area and thin walls, which allows water to easily pass through them.

The image shows plants and their cells with enough water (left) and its lack (right).

The note: Root cells do not contain chloroplasts because they are usually in the dark and cannot photosynthesize.

If the plant does not absorb enough water, it will wilt. Without water, the plant will not be able to photosynthesize fast enough, and may even die.

What is the importance of water for plants?

• Provides dissolved minerals that support plant health;
• Is the medium for transportation;
• Supports stability and uprightness;
• Cools and saturates with moisture;
• It makes it possible to carry out various chemical reactions in plant cells.

Importance of photosynthesis in nature

The biochemical process of photosynthesis uses the energy of sunlight to convert water and carbon dioxide into oxygen and glucose. Glucose is used as building blocks in plants for tissue growth. Thus, photosynthesis is the way in which roots, stems, leaves, flowers and fruits are formed. Without the process of photosynthesis, plants cannot grow or reproduce.

• Producers

Because of their photosynthetic ability, plants are known as producers and serve as the backbone of almost every food chain on Earth. (Algae are the plant's equivalent). All the food we eat comes from organisms that are photosynthetic. We eat these plants directly, or we eat animals such as cows or pigs that consume plant foods.

• Basis of the food chain

Within aquatic systems, plants and algae also form the basis of the food chain. Algae serve as food for, which, in turn, act as a food source for larger organisms. Without photosynthesis in the aquatic environment, life would be impossible.

• Removal of carbon dioxide

Photosynthesis converts carbon dioxide into oxygen. During photosynthesis, carbon dioxide from the atmosphere enters the plant and is then released as oxygen. In today's world where carbon dioxide levels are rising at an alarming rate, any process that removes carbon dioxide from the atmosphere is environmentally important.

• Nutrient cycling

Plants and other photosynthetic organisms play a vital role in nutrient cycling. Nitrogen in the air is fixed in plant tissues and becomes available for making proteins. Trace elements found in the soil can also be incorporated into plant tissue and made available to herbivores further up the food chain.

• photosynthetic addiction

Photosynthesis depends on the intensity and quality of light. At the equator, where sunlight is plentiful all year round and water is not the limiting factor, plants have high growth rates and can become quite large. Conversely, photosynthesis is less common in the deeper parts of the ocean, because light does not penetrate these layers, and as a result, this ecosystem is more barren.

Candidate of Agricultural Sciences A. TARABRIN

BIG SCIENCE IN A SMALL GARDEN

It is known that any plant "produces" food not only from the soil, but also from the air. 95% of the yield is determined by organic substances obtained in green leaves due to the air nutrition of plants - photosynthesis, and only the remaining 5% depend on soil or mineral nutrition.

However, most gardeners focus primarily on mineral nutrition. They regularly fertilize, loosen the soil, water, forgetting about the air nutrition of plants. Even approximately it is impossible to say how much we "do not get" the harvest only because we seem to "do not notice" photosynthesis.

The scale of photosynthesis and its importance in nature can be judged by the amount of solar energy intercepted by green leaves and "conserved" in plants. Every year, land plants alone store as much energy in the form of carbohydrates as one hundred thousand large cities could use in 100 years!

K. A. Timiryazev spoke about the meaning and essence of photosynthesis in 1878 in his famous book "The Life of Plants". "Once, somewhere, a ray of the sun fell on Earth, but it did not fall on barren soil, it fell on a green blade of wheat, or rather on a chlorophyll grain. Hitting it, it went out, ceased to be light, but not disappeared, he only spent money on inner work. In one form or another, it entered the composition of the bread that served us as food. It has been transformed into our muscles, into our nerves. This ray warms us. He sets us in motion. Perhaps at this moment it is playing in our brain... "These words have not become outdated so far. Over the past years, they have only been refined and supplemented with new data on breathing.

In plants, respiration is basically the opposite of photosynthesis. The glucose sugar molecule is oxidized by atmospheric oxygen to carbon dioxide and water, releasing the energy stored in carbohydrates. This energy is used to implement and support all life processes: the absorption and evaporation of water and mineral salts, the growth and development of plants.

It is in the release of energy and directing it to the needs of plants that the main meaning of respiration, which occurs in all living cells of plants, lies.

In fact, breathing supports life itself on Earth! But how exactly does this happen? What form of energy? Without going into details, let's just say that the whole point of breathing is the formation of adenosine triphosphoric acid or ATP for short - an organic substance that includes the nitrogenous base adenine, the five-carbon sugar ribose (together they make up adenosine) and three residues of phosphoric acid interconnected phosphate bond, during the decay of which the energy necessary for all life on Earth is released.

Figuratively, this can be compared with the operation of a battery, which gives energy as needed and is recharged in plants due to solar energy during photosynthesis.

Science and life // Illustrations

Section of a leaf under a microscope. As water enters, the thin outer walls of the cells stretch and pull the thicker inner ones with them. At this time, the stomata (holes) open: oxygen is released from the leaf, and carbon dioxide enters it.

The sun changes its position during the day, describing an arc trajectory of approximately 60° in winter and 120° or more in summer. This must be taken into account when choosing a place for a greenhouse.

Hedge no more than 1.8 meters high, growing south and west of the greenhouse, will reduce the strength of the prevailing winds without causing shading. The fence on the north side, placed close to the greenhouse, does not cast a shadow.

Vents installed on the roof and side walls of the greenhouse capture the flow of cold air and direct it down to the floor. When the stream heats up, it rises and exits through the vents located on the leeward side.

In practice, it turns out that the yield of plants is the difference between photosynthesis and respiration: the higher the photosynthesis and the lower the respiration, the higher the yield, and vice versa. In nature, photosynthesis changes relatively little. But breathing can increase a hundred or even a thousand times. In addition, the ratio between the producing and consuming parts of plants is based on the principle: one with a bipod (photosynthesis) - seven with a spoon (breath). In fact, photosynthesis occurs only in the leaves and only during the day in the light, while plants breathe around the clock, and the accumulation of organic substances (the basis of the crop) is possible only if photosynthesis far exceeds respiration. Unfortunately, this happens much less often than we would like.

In addition, we consider all this now in a somewhat simplified form. In fact, a plant is a single holistic organism in which all processes are closely interconnected, on the one hand, with each other, on the other hand, with their environment: light, heat, moisture. Influence external conditions it is difficult for any plant, because in nature all conditions act on the plant simultaneously. And so far we do not know where the action of one of them ends and the action of the other begins, and what particular condition turns out to be decisive in a given period of growth and development of the plant.

To answer this question, huge greenhouses with a fully controlled climate - climatrons - were built. One of them is the climatron of the Missouri Botanical Garden in St. Louis (USA), built by the prominent American scientist F. Vent. He found that of all the external conditions, the decisive factor in the growth of tomatoes is the night temperature. If at night it rose above 24 or fell below 16 degrees, the fruits did not set at all. The night temperature was also decisive for the potato harvest. The tubers were best formed at a night temperature of about 12 degrees. That is why in the hot summer of 1999 in many areas of our country, including the Moscow region, the potato harvest fell by half compared to previous years.

The temperature often turns out to be almost the "main enemy" of the future harvest, and not only when it is too low, but also in those cases when it is much higher than optimal. German scientists X. Lier, G. Polster found that on clear sunny days, early morning hours are the most productive for harvesting, when the air temperature does not exceed 20-25 ° C. The increase in organic mass at this time is 30 times greater than at higher temperatures.

And this is quite understandable and understandable. It is in the morning hours that photosynthesis reaches its maximum, while respiration, which is strongly dependent on temperature, becomes minimal. This is why plants are especially responsive to morning watering. Water, especially cucumbers, tomatoes, zucchini, requires a lot and preferably not very cold.

Plants get into a completely unusual and unusual environment when they are grown indoors. In greenhouse conditions, all external factors often begin to work as if against plants. Trying to protect plants from the cold with the help of an ordinary film, we cannot save them from overheating, which is much more difficult to do. Indeed, even in spring, the temperature in greenhouses sometimes exceeds the optimum (about 20 degrees). What to say about the period April - August?

On cloudy days, the greenhouse involuntarily turns into a dungeon for plants, the mean rays of the sun barely penetrate the film. Due to the lack of light, photosynthesis drops sharply, while respiration goes on as usual, often overlaps photosynthesis and significantly reduces the future harvest.

Another trouble lies in wait for plants in a greenhouse on clear warm sunny days. The greenhouse turns into a hot desert on such days. "Overheating" of the leaves and the lack of carbon dioxide - the main "raw material" for the creation of carbohydrates - lead to a sharp drop in photosynthesis. Recall that the air contains only 0.03% carbon dioxide, or 3 parts per 10 thousand parts of air, and the lack of this gas in greenhouses during the daytime is quite common. On the other hand, breathing increases a hundred or even a thousand times (depending on temperature). Naturally, during these hours, the accumulation of carbohydrates is out of the question. On the contrary, the plant loses even what was accumulated at a more favorable time.

What should a gardener do? First of all, regularly monitor the temperature with the help of thermometers placed inside and outside the greenhouse or, better, psychrometers (devices with two thermometers, one of which has a reservoir covered with a damp cloth), allowing you to simultaneously monitor the temperature and relative humidity of the air, which is very important . To protect against overheating, it is good to have wide doors on both end walls of the greenhouse. Together with fresh cold air, a stream of carbon dioxide rushes into the greenhouse through the ajar doors, which significantly increases photosynthesis, especially when there is a lack of light.

If this is not enough, side windows are needed, the simplest thing is to nail the film down from the sides to wooden slats and roll it up to the desired height.

A few words about soil nutrition of plants. Until now, many gardeners believe that a bountiful crop of vegetables can be grown only with the help of organic fertilizers. Mineral fertilizers, in their opinion, are solid toxic nitrates.

As for nitrates, there is a very wise commandment: "Do not overfeed!" Fertilizers should be applied as much as the plants need, and not immediately, but fractionally, as they are consumed. The journal "Science and Life" has already written about all this many times (see No. 4, 1992; No. 6, 1993; Nos. 3, 4, 5, 1999).

In conclusion, a few words about growing vegetables on balconies and loggias. We live in one-room apartment On the second floor brick house in the Krasnogorsk district of the Moscow region. There are no buildings or shading trees nearby. The size of the balcony is 3 meters by 70 cm. We grow vegetables according to the method of the American vegetable grower Dr. J. Mittlider on a mixture of sawdust and sand. We take six liter mugs of sawdust (without chips), three mugs of sand (without clay), two tablespoons (with top) of nutrient mixture No. 1 and one tablespoon (with top) of mixture No. 2. Prepare mixture No. 1 as follows: 5 kg ground limestone or dolomite flour mixed with 40 g of boric acid; mix No. 2-3 kg of the Azofoska complex fertilizer is mixed with 450 g (two and a half glasses) of magnesium sulfate and 3 teaspoons (without top) of boric and molybdic acid.

With the prepared mixture, we fill plastic troughs for flowers and basins with 0.5 cm holes in the bottom and sides. For plant nutrition in 1 liter hot water dissolve four teaspoons (with the top) of mixture No. 2. Every time before feeding, we take 100 g of the solution from the prepared container and dilute it 10 times with water. This amount is enough to feed about 10 plants. Feeding frequency: in clear warm sunny weather - once every 7-10 days, in cold and cloudy weather - twice a month.

We grow cucumbers in troughs, tomatoes in basins, 1-3 pieces each, depending on the size of the dishes. We collect a kilogram of tomatoes from each bush. We grow them mainly from purchased seedlings. True, in 1999 they themselves grew seedlings, but they were somewhat late with sowing seeds, and “toy” tomatoes 40 cm high grew out of it, completely strewn with bright red fruits, each the size of a plum. But they were so beautiful that many passers-by involuntarily stopped to admire this miracle.

Each balcony has its own conditions for growing plants, and it cannot be said in advance that all vegetables will grow poorly on the north side, and on the contrary, well on the south. A necessary condition for all cases: the glazed front and especially the end sides of the balcony should open to their entire width. If this is not the case, it is better to leave the balcony or loggia unglazed, and in cold weather bring plants into the room.

GARDENER - NOTE

Many new varieties vegetable crops allow to avoid inconsistency of their requirements with real growing conditions. So, resistant to: lack of light - hybrids of tomato F 1 Olya, eggplant F 1 Pluton, lettuce varieties Ballet, Keltic; to low temperatures - pumpkin varieties Smile, Berlin parsley, Detroit beets, Chernavka radishes, Sirius cucumbers, tomato hybrids F 1 Lelya, F 1 Olya; to drought - cucumber hybrids F 1 Mazay, varieties of radish Zlata, eggplant Quartet.

An interesting fact from biology is that photosynthesis process carried out only during the day using solar energy. Where do plants get energy at night when photosynthesis is not possible? What happens in winter when trees shed their green leaves? Is the life of the plant completely frozen? In the article we will learn everything about plant respiration.

The first thing we usually learn about plants in biology class is that they supply us with oxygen and remove carbon dioxide from the air. Yes, indeed, plants in the process of photosynthesis use CO2 to synthesize sugars and release oxygen. But what about breathing? Do plants breathe?

Plants, like you and me, are related to aerobic organisms which means they need oxygen to survive. In plant cells, as in the cells of other nuclear organisms, there are "energy stations" - mitochondria. For what?

Plant respiration process

During respiration, organic substances (usually carbohydrates) are "burned" in mitochondria using oxygen. The energy currency of cells - ATP is synthesized, water and carbon dioxide are formed, and part of the energy is released in the form of heat.

So, photosynthesis in plants happens in the world, and breathing - 24 hours a day! Photosynthesis is carried out only by the green parts of plants, and all its parts breathe!

day when photosynthesis and respiration are carried out simultaneously, the amount of oxygen produced usually exceeds the amount of carbon dioxide released. At night, only carbon dioxide is released into the air.

This is precisely the reason for the existence of false ideas about vampire plants that take energy (this is explained by excessive consumption of oxygen and the release of carbon dioxide). But have you had to spend the night when in the forest in a tent?

Probably, it was easy to breathe and no one felt a lack of oxygen. It must be understood that the amount of carbon dioxide emitted by a plant or oxygen absorbed at night is negligible compared to the amount of oxygen that it releases during the day.

In fact, humans emit significantly more carbon dioxide when they breathe than plants. In order to form as much carbon dioxide as an ordinary person emits, almost 10,000 kg of plants would be needed! If there are just so many of them in your bedroom, open the doors and windows. Not so many? Sleep well!

So, houseplants - beautiful oxygen suppliers, especially in winter period. Many of them have bactericidal properties, and one of better ways air purification - proper landscaping of the room, including the use of plants that emit phytoncides (natural antibiotics). It has been established that people who have a lot of plants at home are much less likely to get sick, in particular the flu.

What does plant respiration depend on?

leaves, stems, roots and even flowers. Interestingly, roots respire less than photosynthetic leaves. And flower petals (modified leaves) breathe 18-20 times more actively than leaves. Deciduous trees breathe more actively than conifers, and dryland plants - succulents - have a very low respiration rate.

Breathing intensity depends on many factors: time of year, time of day, temperature, light intensity, etc.

In total, in the process of development of cells, tissues, and organs of plants, the intensity of respiration first increases, reaches a maximum at the time of maximum growth rate, and then gradually decreases. A person also requires more energy during a period of active growth.

Young trees spend a third of the daily products of photosynthesis on respiration. Parts of plants that have completed growth (old leaves, stems, wood, or mature seeds) have a low respiration rate, but it never drops to zero.

Plants also have periods of short-term and increased respiration. AT juicy fruits before full maturation, a temporary (2-3 days) activation of respiration occurs - a climacteric rise in respiration. An example of the manifestation of active respiration of plants is the high content of carbon dioxide (up to 13%, normally 0.03%) in the atmosphere of elevators where grain is stored.

As a result of respiration, water, which moistens the seeds and releases heat. It is very difficult to breathe in such rooms. The temperature of the seeds in the elevators can reach + 60-90 ° C, and then the seeds "burn" and lose their ability to germinate.

Breathing depends on atmospheric pressure. American biologist Frank Brown discovered that respiration in the cells of potato tubers increases with rising atmospheric pressure and vice versa. Potato eyes two days earlier than the barometer "foresee" a change in the weather. Before the rain, that is, to reduce pressure, they hold their breath.

from -25 ° C to + 50-60 ° C. For most plants minimum temperature respiration is 0 ° C. In the temperature range from 0 ° C to 30 ° C, with an increase in temperature for every 10 ° C, the intensity of respiration increases only 2 times. At temperatures above 40-50 ° C, respiration slows down.

High temperatures- one of the reasons for the increased respiration of tropical plants, which "burn" 70-80% of the daily products of photosynthesis. The most favorable temperature for respiration is 35-40 ° C, for photosynthesis it is 5-10 ° C lower. Therefore, at high temperatures, the plant intensively consumes organic substances, and their synthesis almost stops, which leads to a decrease in the yield of many plant species.

What happens to plants in winter?

Yes, plants continue breathe in winter! The summer supply of carbohydrates is enough to survive the winter and restore growth in the spring. Buds of fruit trees breathe from -14 ° C, and pine needles - even at -25 ° C!

The processes of respiration in plants affected by the disease are enhanced. University of California professor S. E. Yarwood measured the temperature of the leaves of plants infected with a virus or fungus and compared it with that of a healthy plant. The temperature of diseased parts of the plant increased by as much as 2 ° C.

Don't the plants remind you of sick children? Think of yourself with a temperature of 38.6 ° C. The increased temperature in disease-resistant plants lasts longer than in non-resistant ones. It turns out that under such conditions, cells synthesize protective phenolic compounds that are poisonous to pathogens. Injured plants also breathe heavily, which also leads to a noticeable increase in their temperature in the areas of damage.

Respiration is not only the process of supplying energy for the growth and development of a plant organism. The absorption of water and nutritious mineral elements depends on respiration. At the intermediate stages of respiration, compounds (organic acids, sugar) are formed that are used in various metabolic reactions. In dry conditions, water is released during respiration, which can save the plant from dehydration! Like the camel's water supply mechanisms, right?

How do plants breathe?

Plants do not have special respiratory organs similar to our lungs. Oxygen enters them through natural openings. In addition, plants use the oxygen that is produced during photosynthesis. Above-ground parts of plants receive oxygen from the air directly through pores.

The pores in the leaves are stomata, the pores on the branches of trees are lentils. As a rule, stomata are located on the underside of the leaf. They are formed by special guard cells containing the green pigment chlorophyll. Through the gap, air enters the leaf and moisture evaporates.

On the leaves of aquatic plants, the leaves of which float on the surface of the water (for example, water lilies), stomata are located only on the upper surface of the leaf. The number of stomata per 1 mm 2 leaves averages 300! Fewer stomata were found in tradescantia leaves - 14 per mm 2, and most of all - in marsh oak leaves - 1200 per mm 2. Plant roots have pores.

Mangrove plants grow on the shores of Southeast Asia, Oceania, Australia, Madagascar, Equatorial Africa on the verge of sea and land. These include about 40 species of trees and shrubs that have adapted to the tides, during which they are immersed in water to the top of the crown.

Mangroves called amphibian plants. At low tide, silty ground is exposed, riddled with roots and almost without oxygen. How do mangrove plants survive in such conditions?

Mangroves they receive oxygen with the help of special respiratory roots - pneumatophores, which, unlike ordinary ones, grow upwards, have a porous structure and large intercellular spaces filled with air. The leaves of such plants are also adapted to conditions of lack of oxygen.

So, avicennia- a plant named after the ancient Persian scientist-encyclopedist, physician and philosopher Avicenna, - at high tide, almost all of it is covered
water, and the lower surface of its leaves is densely pubescent. Under water, air bubbles linger between the hairs, the oxygen of which the plant uses during flooding. And the roots of avicenna are upright grow, rising 20-25 cm above the soil surface. Thanks to a well-developed intercellular system, air easily enters the root.

Pneumatophores are found not only in mangroves, but also in plants growing in freshwater swamps of tropical and temperate latitudes. In New Guinea, rattan trees, which are used to make furniture, have them. The stems of this creeper sometimes reach 200-300 m.

In North America, the pneumatophores of the swamp cypress - a tree that grows 35-45 m with a trunk diameter of up to 2 m. Cylindrical pneumatophores of this tree protrude above the soil surface, especially in plants growing near water. In the swamp, people can walk on the pneumatophore, as if on a pavement. Mexicans arrange beehives in them.

Can plants live without oxygen?

Air contains approximately 21% oxygen.
This is quite enough for the normal life of plants. Proper Care behind plants contributes to normal respiration. Wash or dust the leaves regularly. But remember that this should be done very carefully with pubescent leaves, it is advisable to use a special brush.

There are cases when plants find themselves in conditions of lack of oxygen. Most often this problem concerns the roots. In well-aerated soil, oxygen is no less than in air - 7-12%, in poorly cultivated soil, its content is reduced to 2%. That is why you should not water indoor plants abundantly.

Blocking air access to the roots leads to the fact that the plant literally drowns in water, the roots rot, the leaves fall and turn yellow.

How to help such a situation?

Take the plant out of the pot, clean off the soil, rinse and inspect the roots. If they are strong and unharmed, transplant the plant into a pot with fresh, slightly moist soil. Pour expanded clay or small clay shards (drainage) at the bottom of the pot, which will contribute to better gas exchange of the roots.

Place the pot in a shady spot out of direct sunlight and water only when upper layer the soil will dry up to a depth of several centimeters. Even less oxygen in very waterlogged soils. In them, the roots are damaged, die off, and plant growth slows down or stops altogether.

Mimosa, which is able to instantly form its leaves in response to touch, under anaerobic conditions becomes numb and does not respond to any irritation.

Prominent French scientist Louis Pasteur showed that plants in an environment without oxygen form not only CO2, but also alcohol. Under natural conditions, this is possible when wet.

Alcohol is found even in water in plants. Due to frequent floods in the Amazon River basin, stagnant shallow water bodies are formed, which are very well warmed up and illuminated. The flooded plants of such reservoirs turn sugar into alcohol - a fermentation process takes place.

Local residents have learned to use such "water" for making drinks. Some species of Amazonian fish only start spawning when there is a certain amount of alcohol in the waters. Insignificant amounts of alcohol in the fruits of apples, tangerines, etc. However, some plants that live in conditions of constant flooding have adapted to a lack of oxygen.

This is how respiratory roots or pneumatophores arose in mangrove plants. The rush, familiar to you, has a special tissue - aerenchyma, which is characterized by large intercellular spaces filled with air.

Aerenchyma It is also formed in the roots of other plants in response to a lack of oxygen. Additional roots are formed, which are much thicker, have a well-developed aerenchyma and provide respiration processes. Scientists have found that cattail, willow, and other marsh plants, under conditions of normal oxygen supply, breathe 2-3 times weaker than plants that are not adapted to oxygen deficiency (peas, beans, wheat or poplar).

Photosynthesis is the process of formation of organic matter from carbon dioxide and water in the light 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.

There are oxygenic and anoxygenic types of photosynthesis. Oxygenic is much more widespread, it is carried out by plants, cyanobacteria and prochlorophytes. In this article, only it is described; a separate article is devoted to anoxygenic photosynthesis of purple and green bacteria, as well as Helicobacteria.

There are three stages of photosynthesis: photophysical, photochemical and chemical. At the first stage, the absorption of light quanta by pigments, their transition to an excited state and the transfer of energy to other molecules of the photosystem. At the second stage, there is a separation of charges in the reaction center, the transfer of electrons along the photosynthetic electron transport chain, which ends with the synthesis of ATP and NADPH. The first two stages are collectively referred to as the light-dependent stage of photosynthesis. The third stage occurs already without the obligatory participation of light and includes biochemical reactions of the synthesis of organic substances using the energy accumulated at the light-dependent stage. Most often, the Calvin cycle and gluconeogenesis, the formation of sugars and starch from carbon dioxide in the air, are considered as such reactions.

Respiration is the main form of dissimilation in humans, animals, plants and many microorganisms. During respiration, energy-rich substances belonging to the body are completely decomposed into energy-poor inorganic end products (carbon dioxide and water), using molecular oxygen for this.

External respiration is understood as gas exchange between the body and the environment, including the absorption of oxygen and the release of carbon dioxide, as well as the transport of these gases within the body.

Internal (cellular) respiration includes biochemical processes in the cytoplasm of cells and mitochondria, leading to the release of energy.

In organisms that have large surface areas in contact with the external environment, respiration can occur due to the diffusion of gases directly to the cells (for example, in plant leaves, in cavitary animals). With a small relative surface area, gases are transported by blood circulation (in vertebrates, etc.) or in the trachea (in insects).

Chemosynthesis is a method of autotrophic nutrition, in which the source of energy for the synthesis of organic substances from CO2 is the oxidation of inorganic compounds. A similar option for obtaining energy is used only by bacteria. The phenomenon of chemosynthesis was discovered in 1887 by the Russian scientist S. N. Vinogradsky.

It should be noted that the energy released in the oxidation reactions of inorganic compounds cannot be directly used in assimilation processes. First, this energy is converted into the energy of macroergic bonds of ATP and only then is it spent on the synthesis of organic compounds.

13. Energy inecosystems

Recall that an ecosystem is a collection of living organisms that continuously exchange energy, matter and information with each other and with the environment. Consider first the process of energy exchange. Energy is defined as the ability to do work. The properties of energy are described by the laws of thermodynamics.

The first law (beginning) of thermodynamics or the law of conservation of energy states that energy can change from one form to another, but it does not disappear and is not created anew. The second law (beginning) of thermodynamics or the law of entropy states that entropy can only increase in a closed system. With regard to energy in ecosystems, the following formulation is convenient: processes associated with energy transformations can occur spontaneously only if the energy passes from a concentrated form to a diffuse one, that is, it degrades. A measure of the amount of energy that becomes unavailable for use, or otherwise a measure of the change in order that occurs when energy is degraded, is entropy. The higher the order of the system, the lower its entropy. Thus, any living system, including an ecosystem, maintains its vital activity due, firstly, to the presence in the environment of an excess of free energy (the energy of the Sun); secondly, the ability, due to the arrangement of its constituent components, to capture and concentrate this energy, and using it to dissipate it into environment. Thus, first capturing and then concentrating energy with the transition from one trophic level to another provides an increase in orderliness, organization of a living system, that is, a decrease in its entropy.

14. Types of relationships between living organisms. Intraspecific and interspecific.

Relationships between organisms can be divided into interspecific and intraspecific. Interspecies relationships are usually classified according to the “interests” on the basis of which organisms build their relationships:

Interspecies interactions are much more diverse:

-neutralism (both species do not have any effect on each other);

-competition (both species have an adverse effect on each other);

Mutualism (both species cannot exist without each other);

-predation ( predatory look feeds on its prey)

-amensalism (one organism inhibits the development of another);

-commensalism (a commensal benefits from another species that is not indifferent to this association).

Intraspecific competition:

- direct competition - animals fight each other to the death. In plants - allopathy - the release of toxins.

- indirect competition - indirect, i.e. not directly.

Intraspecific relationships:

- competition;

-rivalry;

- mutual assistance;

- cooperation (herd).

15. Populations. Population structure. Mortality, birth rate, survival rate. survival curves. Population dynamics.

Population is a term used in various branches of biology, as well as in genetics, demography and medicine. The most general meaning is in the literal translation. A population is the human, animal, or plant population of an area. In European languages, this concept primarily refers to a person and, secondarily, to other living organisms. In Russian, population has a more technical meaning as a term predominantly used in biological and medical research. In biology: a population is a certain set of individuals of a species that is part of a particular biogeocenosis and manifests itself in it with its specific functional and energy impact. Modern genetics carefully studies the history of modern ethnic groups according to ethnogenetic data to a depth of tens of millennia - since the exodus of the first "homo sapiens" communities from Africa. Genetic transformations of populations were accompanied by ethno-cultural ones, which turned populations in the last millennia into well-known historical peoples.

Population structure The demographic structure of a population is primarily understood as its sex and age composition. In addition, it is customary to talk about the spatial structure of the population - that is, about the features of the distribution of individuals in the population in space. Knowledge of the population structure allows the researcher to draw conclusions about its well-being or disadvantage. For example, if there are no generative (that is, capable of producing offspring) individuals in the population and at the same time there are many old-aged (senile) individuals, then an unfavorable forecast can be made. Such a population may not have a future. It is desirable to study the structure of the population in dynamics: knowing its change over several years, one can speak much more confidently about certain trends. Age structure of the population. This type of structure is associated with the ratio of individuals of different ages in the population.

Mortality is a statistic that estimates the number of deaths.

Birth rate is a demographic term, defined as the ratio of the number of births in a period per 1,000 inhabitants.

Survival - the number of individuals (as a percentage) that have survived in a population over a certain period of time. Usually, survival is determined for different ages and sex groups for different seasons, years, periods of increased mortality.

SURVIVAL - the proportion of individuals in a population that survived to reproduction. SURVIVAL CURVE:

In a differential form, the dependence is defined as dN / dt = rN ((k-N) / k), N is the number. In the mat. expression includes the resistance of the medium. r - hostile

speed pop.k – max. the number of individuals.

r-species - pioneers, k-species - with a tendency to balance

17. Community productivity. ecological pyramids.

COMMUNITY PRODUCTIVITY - an important functional indicator of the community, as well as its individual elements (autotrophic and heterotrophic components, individual trophic levels, populations of any species) is their ability to create (produce) new biomass.

The ecological pyramid is a graphic representation of the relationship between producers, consumers and decomposers in an ecosystem.

These pyramids arise in ecosystems (biogeocenoses) in food chains. Food chains are formed in ecosystems as a result of life various kinds. Thus, producers (autotrophic plants) are the only creators of organic matter. In the biogeocenosis, there are necessarily herbivorous and carnivorous animals (consumers of the 1st, 2nd, etc. orders), and, finally, destroyers of organic residues (decomposers). In the ecosystem, the species belonging to these three main groups are in complex relationships and form power circuits,

Ecological pyramid rule

The pattern according to which the amount of plant matter that serves as the basis of the food chain is approximately 10 times greater than the mass of herbivorous animals, and each subsequent food level also has a mass 10 times less.

Power circuit

A chain of interconnected species that sequentially extract organic matter and energy from the original food substance. Each previous link in the food chain is food for the next link.

19. Ecology of communities and ecological successions.

A community is a set of interacting populations occupying a certain territory, a living component of an ecosystem. The community functions as a dynamic unit with different trophic levels, energy flow and nutrient cycling through it.

The community structure is built up gradually over time. An example that can be used as a model for community development is the colonization of rock outcrops by organisms on a recently formed volcanic island. Trees and shrubs cannot grow on bare rock, as there is no soil necessary for them. However, algae and lichens different ways fall into such territories and populate them, forming pioneer communities. The gradual accumulation of dead and decaying organisms and the erosion of rock as a result of weathering lead to the formation of a soil layer sufficient for larger plants, such as mosses and ferns, to settle here. Eventually, these plants will be followed by even larger and more nutrient-demanding seed forms, including grasses, shrubs, and trees.

Such a change of some species by others over a certain period of time is called ecological succession. Final community - stable, self-renewing and in balance with the environment - is called a climax community. In the animal world of these communities, there is also a change of some species by others, largely due to a change in vegetation, but this process also depends on which animals can migrate from neighboring communities.

The type of succession described above, beginning with the colonization of an exposed rock or other surface devoid of soil (such as sand or a former glacier bed), is called primary succession. In contrast, secondary is called succession, which begins where the surface is completely or largely devoid of vegetation, but was previously under the influence of living organisms and has an organic component. These are, for example, forest clearings, burnt areas or abandoned agricultural land. Here, seeds, spores and vegetative propagation organs, such as rhizomes, can be preserved in the soil, which will affect succession. Both in primary and secondary successions, the flora and fauna of the surrounding areas are the main factor determining the types of plants and animals included in the succession as a result of random dispersal and migrations.

20. Biodiversity is the basis of ecosystem sustainability.

Biodiversity (biological diversity) is the diversity of life in all its manifestations. In a narrower sense, biodiversity refers to diversity at three levels of organization: genetic diversity(the diversity of genes and their variants - alleles), the diversity of species in ecosystems, and, finally, the diversity of the ecosystems themselves.

Biodiversity is a key concept in conservation discourse. Biodiversity has been defined as “the variability of living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, diversity of species and diversity of ecosystems ".

There are three main types of biodiversity:

- genetic diversity, reflecting intraspecific diversity and due to the variability of individuals;

- species diversity, reflecting the diversity of living organisms (plants, animals, fungi and microorganisms). At present, about 1.7 million species have been described, although their total number, according to some estimates, is up to 50 million;

- Ecosystem diversity encompasses differences between ecosystem types, diversity of habitats and ecological processes. They note the diversity of ecosystems not only in terms of structural and functional components, but also in terms of scale - from microbiogeocenosis to the biosphere;

Sometimes a variety of landscapes is singled out as a separate category, reflecting the peculiarities of the territorial structure and the influence of local, regional and national cultures of society.

There are many reasons for the need to preserve biodiversity: the need for biological resources to meet the needs of mankind (food, materials, medicines, etc.), ethical and aesthetic aspects (life is valuable in itself), etc. However, the main reason for the conservation of biodiversity is that it plays a leading role in ensuring the sustainability of ecosystems and the Biosphere as a whole (absorption of pollution, climate stabilization, provision of conditions suitable for life). Biodiversity performs a regulatory function (see the Concept of biotic regulation, Gorshkov V.G.) in the implementation of all biogeochemical, climatic and other processes on Earth. Each species, no matter how insignificant it may seem, contributes to ensuring the sustainability of not only the “native” local ecosystem, but the Biosphere as a whole.

21. Homeostasis of systems.

Homeostasis is the ability of an open system to maintain the constancy of its internal state through coordinated reactions aimed at maintaining dynamic balance.

Homeostasis is the ability of an ecosystem to self-regulate, i.e. the ability to maintain balance.

Homeostasis is based on the principle of feedback.

– Negative (the deviation from the norm decreases)

– Positive (the deviation from the norm increases)

It is possible to maintain homeostasis within the limit of negative feedback. In any ecosystem where food chains exist, there are certain channels for transmitting information: chemical, genetic, energy, etc. The stability of a community is determined by the number of links in the trophic pyramid. The balance of the ecological cycle and the balance of ecosystems is ensured by a feedback mechanism: the control component receives information from the controlled one and accordingly makes adjustments to the further management process. An example of deer-wolves. The occurrence of interference is a violation of feedback. Strong interference - the death of ecosystems. Interference: partial (toxic chemicals, shooting of animals, fishing); limiting - destroy the ecosystem (destruction of the main trophic level). A homeostatic plateau is an area within which an ecosystem is able to maintain its stability despite stressful influences.

22. Circulation of substances. Large (geological) and small (biogeochemical). Exchange and reserve funds.

The circulation in the biosphere is understood as the recurring processes of transformations and spatial displacements of substances that have a certain forward movement, expressed in qualitative and quantitative differences in individual cycles. There are 2 cycles - large (geological) and small (biotic). A large (geological) cycle of matter proceeds from several thousand to several million years, including such processes as the water cycle and land denudation. DUNUDATION of land consists of the total withdrawal of land matter (52990 million tons/year), the total supply of matter to land (4043 million tons/year) and amounts to 48947 million tons/year. Anthropogenic intervention leads to an acceleration of denudation, leading, for example, to earthquakes in the zones of reservoirs built in seismically active areas. SMALL (biotic) circulation of substances occurs at the level of biogeocinosis or biogeochemical cycle.

The energy balance of the biosphere is the ratio between absorbed and radiated energy. It is determined by the arrival of the energy of the Sun and cosmic rays, which is absorbed by plants during photosynthesis, part is converted into other types of energy, and another part is dissipated in outer space.

Circulation in the biosphere - repetitive processes of transformations and spatial movements of substances that have a certain forward movement, expressed in qualitative and quantitative differences in individual cycles.

23. Hydrological cycle.

The water cycle on Earth, also called the hydrological cycle, involves the entry of water into the atmosphere through evaporation and its return back as a result of condensation and precipitation.

In general terms, the water cycle always consists of evaporation, condensation and precipitation. But it includes three main "loops":

surface runoff: water becomes part of surface water;

evaporation - transpiration: water is absorbed by the soil, retained as capillary water, and then returned to the atmosphere, evaporating from the earth's surface, or absorbed by plants and released as vapor during transpiration;

ground water: water enters and moves through the ground, feeding wells and springs and thus re-entering the surface water system.

According to the scheme of the water cycle, the fund of water in the atmosphere is small; the turnover rate is higher and the residence time is shorter than for carbon dioxide. The global impact of human activities is beginning to affect the water cycle. Accounting for precipitation and river flow throughout the world is now well established; it is necessary, however, as soon as possible to establish a more complete control of all the main ways of movement of water in the cycle. Two other aspects of the water cycle should be emphasized.

1. Note that the sea loses due to evaporation more water than receives with precipitation; on land, the situation is reversed. In other words, that part of the precipitation that supports terrestrial ecosystems, including those supplying food to humans, comes from evaporation from the sea. It has been established that in many areas 90% of precipitation is brought from the sea.

2. According to estimates, the weight of the water of fresh lakes and rivers is 0.25 geogram (1 geogram = 1020 g), and the annual runoff is 0.2 geogram; therefore, the turnaround time is about a year. The difference between the amount of precipitation per year (1.0 geograms) and runoff (0.2 geograms) is 0.8; this is the value of the annual water inflow into the subsoil aquifers. As already mentioned, an increase in runoff as a result of human activities can reduce the groundwater fund, which is very important for the cycle. We should be returning more water to aquifers rather than trying to store all of it in lakes where it evaporates faster

24. Cycles of carbon, nitrogen, phosphorus and sulfur.

THE CARBON CYCLE.

Carbon is found in nature both in the free state and in the form

numerous connections. Free carbon occurs as diamond and

graphite.

Carbon compounds are very common. In addition to fossil coal, in the bowels

The earth contains large accumulations of oil, which is a complex mixture

various carbon-containing compounds, mainly hydrocarbons.

In addition, plant and animal organisms are composed of substances in

the formation of which carbon plays a major role.

Carbon dioxide is absorbed by producing plants and in the process

photosynthesis is converted into carbohydrates, proteins, lipids and other organic

connections. These substances with food are used by consumer animals.

At the same time, a reverse process takes place in nature. All living

Organisms breathe by releasing carbon dioxide into the atmosphere.

Dead plant and animal remains and animal excrement decompose

(mineralized) by decomposer microorganisms. Final product

mineralization - carbon dioxide - is released from the soil or water bodies into

atmosphere. Part of the carbon is stored in the soil in the form of organic

connections.

Carbon enters the atmosphere from

car exhaust gases, with smoke emissions from plants and factories.

In the process of carbon cycle in the biosphere, energy

resources - oil, coal, combustible gases, peat, wood, which

widely used by man. All these substances are produced

photosynthetic plants over time. Age of forests - tens and

hundreds of years; peat bogs - thousands of years; coal, oil, gases - hundreds of millions

years. It should be taken into account that wood and peat are renewable resources;

reproduced over relatively short periods of time, and oil,

combustible gas and coal are irreplaceable resources.

THE NITROGEN CYCLE.

Most of Nitrogen is found in nature in a free state. Inorganic nitrogen compounds do not occur in nature in large quantities.

seams on the Pacific coast in Chile. The soil contains little

amounts of nitrogen, preferably in the form of salts of nitric acid. But in the form

complex organic compounds - proteins - nitrogen is part of all living

organisms.

Nitrogen is an essential element. It is found in proteins and nucleic

acids. The nitrogen cycle is closely related to the carbon cycle. Partially

nitrogen comes from the atmosphere due to the formation of nitric oxide (IV) from

nitrogen and oxygen under the action of electrical discharges during thunderstorms.

However, the bulk of nitrogen enters the water and soil due to fixation.

air nitrogen by living organisms.

The most effective nitrogen fixers are nodule bacteria that live in the roots of legumes. Nitrogen from various sources enters the roots of plants, is absorbed by them and transported to the stems and leaves, where proteins are built in the process of biosynthesis.

Plant proteins serve as the basis of nitrogen nutrition for animals. After dying

organisms, proteins under the action of bacteria and fungi decompose with the release of

ammonia. Ammonia is partly consumed by plants and partly used

decomposer bacteria. As a result of the life processes of some

bacteria convert ammonia to nitrate. Nitrates, like ammonium ions,

consumed by plants and microorganisms. Part of the nitrates under the action

a special group of bacteria is reduced to elemental nitrogen, which

released into the atmosphere. This closes the nitrogen cycle in nature.

PHOSPHORUS CYCLE

Due to

easy oxidizability phosphorus in the free state in nature is not

meets. Of the natural compounds of phosphorus, the most important is

calcium orthophosphate, which, in the form of the mineral phosphorite, sometimes forms

large deposits. The richest deposits of phosphorites are located in the South

Kazakhstan in the Karatau mountains. Phosphorus, like nitrogen, is essential for all living things.

beings, as it is part of some proteins like vegetable,

as well as animal origin. Plants contain phosphorus as the main

way in the proteins of seeds, in animal organisms - in the proteins of milk, blood,

brain and nervous tissues. As an acid residue of phosphoric acid

phosphorus is a part of nucleic acids - complex organic

polymer compounds directly involved in the processes

transmission of hereditary properties of a living cell. Raw material for receiving

phosphorus and its compounds are phosphorites and apatites. natural phosphorite

or apatite is crushed, mixed with sand and coal and heated in furnaces with

using electric current without access to air in all living organisms.

Its main source is rocks (mainly igneous

nye). It is represented mainly by apatite and fluorapatite. In sedimentary rocks, it is usually vivianite, wavelite, phosphorite. With the formation of the biosphere, the release of phosphorus from rocks increased, resulting in a significant redistribution of it. In the transformation of phosphorus

plays a big role living matter. Organisms absorb phosphorus from soils

aqueous solutions. Phosphorus is found in proteins, nucleic acids, and

other organic compounds.

Especially a lot of phosphorus in the bones of animals. With doom

organisms, phosphorus returns to the soil, it is concentrated in the form

marine phosphate nodules, fish bone deposits, which creates conditions for

the formation of phosphorus-rich rocks, which in turn serve

source of phosphorus in the biogenic cycle.

THE SULFUR CYCLE.

Sulfur occurs in nature both in the free state (native sulfur) and

and in various compounds. Sulfur compounds are very common

various metals. Of the sulfur compounds in nature are also common

sulfates, mainly calcium and magnesium. Finally, sulfur compounds

Sulfur is widely used in the national economy. Sulfur in the form of sulfur

used to kill certain plant pests. It applies

also for making matches, ultramarine (blue dye), carbon disulfide and

a number of other substances.

The sulfur cycle occurs in the atmosphere and lithosphere. The entry of sulfur into

atmosphere occurs in the form of sulfates, sulfuric anhydride and sulfur from

lithosphere during volcanic eruptions, in the form of hydrogen sulfide due to

decomposition of pyrite (FeS2) and organic compounds. anthropogenic source

sulfur emissions into the atmosphere are thermal power plants and other

objects where coal, oil and other hydrocarbons are burned, and

the entry of sulfur into the lithosphere, in particular into the soil, occurs with fertilizers

and organic compounds. Transport of sulfur compounds in the atmosphere

is carried out by air currents, and fallout to the earth's surface or

in the form of dust, or with atmospheric precipitation in the form of rain (acid rain) and

snow. On the surface of the Earth in the soil and water bodies, binding occurs

sulfate and sulfite sulfur compounds with calcium to form gypsum

(CaSO4). In addition, sulfur is buried in sedimentary rocks with

organic residues of plant and animal origin, of which

further coal and oil are formed. In the soil change

sulfur compounds occurs with the participation of sulfobacteria using

sulfate compounds and emitting hydrogen sulfide, which, entering into

atmosphere and being oxidized again turns into sulfates. In addition, hydrogen sulfide

soil can be reduced to sulfur, which denitrifying

oxidized to sulfates by bacteria.

25. Principles of functioning of ecosystems.

Receiving resources and getting rid of waste occur within the cycle of all elements.

This principle is in harmony with the law of conservation of mass. Since atoms do not arise, disappear, or turn into one another, they can be used indefinitely in a wide variety of compounds and their supply is practically unlimited. This is exactly what happens in natural ecosystems.

It is very important to emphasize, however, that the biological cycle is not carried out solely at the expense of matter, since it is the result of the activity of organisms, which require constant energy costs supplied by the Sun to ensure their vital activity. The energy of the sun's rays absorbed by green plants, unlike chemical elements, cannot be used by organisms indefinitely. This conclusion follows from the second law of thermodynamics: when energy is transformed from one form to another, that is, when work is performed, it partially transforms into a thermal form and dissipates in the environment.

Consequently, each cycle of the cycle, which depends on the activity of organisms and is accompanied by energy losses from them, requires more and more new energy supplies.

So, the existence of ecosystems of any rank and of life on Earth in general is due to the constant circulation of substances, which, in turn, is supported by a constant influx of solar energy. This is the second basic principle of the functioning of ecosystems:

Ecosystems exist due to non-polluting and practically eternal solar energy, the amount of which is relatively constant and abundant.

26. Environmental quality. MPC. The effect of MPC summation with a large number of pollutants. MPC of working areas. MPC average daily.

The quality of the environment is the state of natural and human-transformed ecological systems that preserves their ability for constant metabolism and energy, reproduction of life.

Maximum Permissible Concentration (MPC) - a sanitary and hygienic standard for the content of a harmful substance in the environment (or production) environment, approved by law, which practically does not affect human health and does not cause adverse effects.

Many toxic substances have a summation effect, i.e. their mixtures have a more toxic effect on living organisms than individual components. In this case, it is necessary to take into account the combined effect of impurities on humans and the environment.

Maximum allowable concentration of a harmful substance in the air of the working area. This concentration should not cause workers, with daily inhalation for 8 hours, for the entire period of working experience of any diseases or deviations from the norm in the state of health that could would be discovered modern methods research directly during work or in the long term.

MPCs.s is the average daily maximum permissible concentration of a harmful substance in the air of populated areas. This concentration of a harmful substance should not have a direct or indirect harmful effect on the human body under conditions of indefinitely long round-the-clock inhalation.

27. Environmental monitoring. Classification of monitoring systems.

Monitoring is the systematic collection and processing of information that can be used to improve the decision-making process, as well as indirectly to inform the public or directly as a feedback tool for project implementation, program evaluation or policy development. It has one or more of three organizational functions:

Identifies the status of critical or changing environmental phenomena for which a course of action will be developed for the future;

can help build relationships with one's environment by providing feedback on previous successes and failures of a particular policy or program;

can be useful for establishing compliance with rules and contractual obligations.

classification

(monitoring of impact sources) Impact sources->

(Monitoring of influence factors)Influence factors:Physical,Biological,Chemical->

(Monitoring the state of the biosphere): Natural environments: Atmosphere, Ocean, Land surface with rivers and lakes, Biota

28. Hydrosphere. Pollution of the hydrosphere. The concepts of COD, BOD.

The hydrosphere is the totality of all the water reserves of the Earth.

Most of the water is concentrated in the ocean, much less - in the continental river network and groundwater. There are also large reserves of water in the atmosphere, in the form of clouds and water vapor. Over 96% of the volume of the hydrosphere is seas and oceans, about 2% is groundwater, about 2% is ice and snow, and about 0.02% is land surface water. Part of the water is in a solid state in the form of glaciers, snow cover and permafrost, representing the cryosphere.

Surface waters, occupying a relatively small share in the total mass of the hydrosphere, nevertheless play an important role in the life of our planet, being the main source of water supply, irrigation and watering. This geosphere is in constant interaction with the atmosphere, the earth's crust and the biosphere.

The interaction of these waters and mutual transitions from one type of water to another constitute a complex water cycle on the globe. The hydrosphere was the first place where life originated on Earth. Only at the beginning of the Paleozoic era did the gradual migration of animal and plant organisms to land begin.

The main types of pollution of the hydrosphere.

1. Pollution with oil and oil products leads to the appearance of oil slicks, which impedes the processes of photosynthesis in water due to the cessation of access to sunlight, and also causes the death of plants and animals. Each ton of oil creates an oil film on an area of ​​up to 12 square meters. km. Restoration of affected ecosystems takes 10-15 years.

2. Pollution with wastewater as a result of industrial production, mineral and organic fertilizers as a result of agricultural production, as well as municipal wastewater leads to eutrophication of water bodies and their enrichment nutrients, leading to excessive development of algae, and to the death of other aquatic ecosystems with stagnant water (lakes, ponds), and sometimes to waterlogging of the area.

3. Pollution with heavy metal ions disrupts the vital activity of aquatic organisms and humans.

4. Acid rain leads to acidification of water bodies and to the death of ecosystems.

5. Radioactive contamination is associated with the discharge of radioactive waste into water bodies.

6. Thermal pollution causes the discharge of heated water from thermal power plants and nuclear power plants into water bodies, which leads to the massive development of blue-green algae, the so-called water bloom, a decrease in the amount of oxygen and negatively affects the flora and fauna of water bodies.

7. Mechanical pollution increases the content of mechanical impurities.

8. Bacterial and biological pollution is associated with various pathogenic organisms, fungi and algae.

COD is the amount of oxygen in milligrams per 1 liter of water required to oxidize carbonaceous substances toCO2 andH2O, nitrogen-containing to nitrates, sulfur-containing to sulfates, phosphorus-containing to phosphates.

BOD is an indicator used to characterize the degree of pollution of wastewater with organic impurities that can be decomposed by microorganisms with oxygen consumption.

29. Pollution of seas and rivers. Self-purification of the hydrosphere.

The process of self-purification in the hydrosphere is associated with the water cycle in nature. In reservoirs, this process is ensured by the combined activity of the organisms that inhabit them. Under ideal conditions, the self-purification process proceeds quickly enough, and the water restores its original state. Factors that determine the self-purification of water bodies can be divided into three groups: physical, chemical, biological.

Among the physical factors, the main ones are dilution, dissolution and mixing of incoming contaminants. For example, a strong river flow provides good mixing, resulting in a reduction in the concentration of suspended particles. The settling of insoluble particles in the water during the sedimentation of polluted waters contributes to the self-purification of water bodies. Under the action of gravity, microorganisms are deposited on organic and inorganic particles and gradually sink to the bottom, while being exposed to other factors. An increase in the intensity of the action of physical factors contributes to the rapid death of the polluting microflora. When exposed to ultraviolet radiation, water is disinfected, based on the direct destructive effect of these rays on protein colloids and enzymes of the protoplasm of microbial cells. Ultraviolet radiation can affect not only ordinary bacteria, but also spore organisms and viruses.

Oil and oil products are the main pollutants of the water basin. On tankers carrying oil and its derivatives, before each next loading, as a rule, containers (tanks) are washed to remove the remnants of the previously transported cargo. Wash water, and with it the rest of the cargo, is usually dumped overboard. In addition, after the delivery of oil cargoes to the ports of destination, tankers are most often sent to the point of new loading empty. In this case, to ensure proper draft and navigation safety, the ship's tanks are filled with ballast water. This water is polluted with oil residues, and before loading oil and oil products, it is poured into the sea. Of the total cargo turnover of the world's maritime fleet, 49% currently falls on oil and its derivatives. Every year, about 6,000 tankers of international fleets transport 3 billion tons of oil. As the transportation of oil cargo increased, more and more oil began to fall into the ocean during accidents.

Purification of water in the ocean occurs due to the filtration capacity of plankton. For 40 days, a surface layer of water hundreds of meters thick passes through the plankton filtration apparatus.

30. Wastewater. Eutrophication of water bodies.

Wastewater - any water and precipitation discharged into water bodies from the territories of industrial enterprises and populated areas through the sewerage system or by gravity, the properties of which have been degraded as a result of human activity.

Wastewater can be classified according to the following criteria:

by origin:

industrial (industrial) wastewater (formed in technological processes in the production or extraction of minerals), are discharged through the industrial or combined sewerage system

domestic (household-faecal) wastewater (formed in residential premises, as well as in domestic premises at work, for example, showers, toilets), is discharged through a domestic or combined sewerage system

atmospheric wastewater (divided into rainwater and meltwater, that is, formed during the melting of snow, ice, hail), as a rule, are discharged through the system storm sewer

Eutrophication is the enrichment of rivers, lakes and seas with nutrients, accompanied by an increase in the productivity of vegetation in water bodies. Eutrophication can be the result of both natural aging of a reservoir and anthropogenic impacts. The main chemical elements contributing to eutrophication are phosphorus and nitrogen.

Eutrophic water bodies are characterized by rich littoral and sublittoral vegetation and abundant plankton. Artificially unbalanced eutrophication can lead to the rapid development of algae (“blooming” of waters), oxygen deficiency and the death of fish and other animals. This process can be explained by the low penetration of sunlight into the depths of the reservoir (due to phytoplankton on the surface of the reservoir), and as a result, the absence of photosynthesis in bottom plants, and hence the lack of oxygen.

31.lithosphere. Types of pollution of the lithosphere.

The lithosphere is the hard shell of the Earth. It consists of the earth's crust and the upper part of the mantle, up to the asthenosphere, where the seismic wave velocities decrease, indicating a change in the plasticity of the rocks.

The lithosphere is divided into blocks - lithospheric plates, which move along the relatively plastic asthenosphere. The section of geology on plate tectonics is devoted to the study and description of these movements.

The lithosphere under oceans and continents varies considerably. The lithosphere under the oceans has undergone many stages of partial melting as a result of the formation of oceanic crust, it is highly depleted in low-melting rare elements and mainly consists of dunites and harzburgites.

The lithosphere is polluted by liquid and solid pollutants and wastes.

Sources of soil pollution can be classified as follows

Residential buildings and public utilities. The composition of pollutants in this source category is dominated by household waste, food waste, construction debris, waste heating systems, worn-out household items, etc. All this is collected and taken to landfills. For large cities, the collection and destruction of household waste in landfills has become an intractable problem. The simple burning of garbage in city dumps is accompanied by the release of toxic substances. When burning such objects, for example, chlorine-containing polymers, highly toxic substances are formed - dioxides. Despite this, in last years Methods are being developed for the destruction of household waste by incineration. A promising method is the burning of such garbage over hot melts.

Industrial enterprises. Solid and liquid industrial waste constantly contains substances that can have a toxic effect on living organisms and plants. For example, non-ferrous heavy metal salts are usually present in waste from the metallurgical industry. The engineering industry releases cyanides, arsenic and beryllium compounds into the environment; in the production of plastics and artificial fibers, wastes containing phenol, benzene, styrene are formed; in the production of synthetic rubbers, catalyst wastes, substandard polymer clots get into the soil; during the production of rubber products, dust-like ingredients, soot, which settle on the soil and plants, waste rubber-textile and rubber parts, enter the environment, and during the operation of tires - worn-out and failed tires, inner tubes and rim tapes. The storage and disposal of used tires is currently an unresolved problem, as it often causes large fires that are very difficult to extinguish.

Site search:

2015-2020 lektsii.org -