Respiration and metabolism in plants

Plants, like all living organisms, constantly breathe. To do this, they need oxygen. It is needed by both unicellular and multicellular plants. Oxygen is involved in the vital processes of cells, tissues and organs of a plant.

Most plants obtain oxygen from the air through stomata and lenticels. Aquatic plants consume it from the water with the entire surface of the body. Some plants growing in wetlands have special respiratory roots that absorb oxygen from the air.

Breath- a complex process that occurs in the cells of a living organism, during which, during the decay organic matter the energy needed for the life processes of the body is released. The main organic matter involved in the respiratory process are carbohydrates, mainly sugars (especially glucose). The intensity of respiration in plants depends on the amount of carbohydrates accumulated by shoots in the light.

Respiration is the process of decomposition of organic nutrients to inorganic substances (carbon dioxide and water) with the participation of oxygen, accompanied by the release of energy, which is used by the plant for life processes.

Respiration is a process opposite to photosynthesis. Let us compare the processes of respiration and photosynthesis in the cells of a green leaf of a plant.

The process of respiration is associated with the continuous consumption of oxygen day and night. The process of respiration is especially intensive in young tissues and organs of the plant. The intensity of respiration is determined by the needs of plant growth and development. A lot of oxygen is required in the areas of cell division and growth. The formation of flowers and fruits, as well as damage and especially tearing off of organs, is accompanied by an increase in respiration in plants. At the end of growth, with yellowing of the leaves, and especially in winter, the intensity of respiration decreases markedly, but does not stop.

Respiration is an indispensable condition for plant life.

In order to live, a plant must necessarily receive the substances and energy it needs through nutrition and respiration.

Absorbed substances in the process of transformations in cells and tissues become substances from which the plant builds its body. All transformations of substances occurring in the body are always accompanied by energy consumption. A green plant (as an autotrophic organism), absorbing light energy, converts it into chemical energy and accumulates it in complex organic compounds. In the process of respiration, during the breakdown of organic substances, this energy is released and used by the plant for the transformation of substances and vital processes that occur in cells.

Both of these processes - photosynthesis and respiration - go through numerous successive chemical reactions in which one substance is converted into another.

For example, in the process of photosynthesis, sugars are formed from carbon dioxide and water, which are then converted through a series of intermediate reactions into starch, fiber or proteins, fats and vitamins - substances that a plant needs for nutrition and energy storage.

The entire process of respiration takes place in the cells of the plant organism. It consists of two stages, during which complex organic substances are split into simpler, inorganic substances - carbon dioxide and water. At the first stage, with the participation of special proteins that accelerate the process (enzymes), the breakdown of glucose molecules occurs. As a result, simpler organic compounds are formed from glucose and little energy is released. This stage of the respiratory process occurs in the cytoplasm.

At the second stage, simple organic substances formed at the first stage, interacting with oxygen, are oxidized - they form carbon dioxide and water. This releases a lot of energy. The second stage of the respiratory process proceeds only with the participation of oxygen in special cell organelles - mitochondria .

Thus, in the process of respiration, more complex organic substances are split into simple inorganic compounds - carbon dioxide and water. In this case, the plant is provided with released energy. At the same time, there is a transfer of various chemical elements from one compound to another. These transformations of substances in the body are called metabolism . Metabolism is one of the important signs of life.

Metabolism- this is a combination of various chemical transformations occurring in the body that ensure the growth and development of the organism, its reproduction and constant contact with the environment.

Metabolism binds all the organs of the body into a single whole. At the same time, thanks to the metabolism, the body unites with the environment. From it, the plant absorbs substances through the roots and leaves and releases the products of its vital activity into the environment. Breathing, like nutrition, is a necessary condition for metabolism, and hence for the life of the body.

Table 3.2. Character traits photosynthesis and respiration processes

1. Modifications of underground shoots

3. Vegetative reproduction.

Air nutrition of plants - photosynthesis. Photosynthesis is the creation of organic matter. Root nutrition gives the plant only mineral salts and water. The plant receives organic substances and the energy contained in them in the process photosynthesis (from the Greek photos - "light" and synthesis - "connection"). Photosynthesis takes place in chloroplasts. During this process, due to the energy of sunlight, the plant, using the green chlorophyll of the leaves, forms the organic substances it needs from inorganic substances - carbon dioxide and water. Since air is the main supplier of carbon dioxide for photosynthesis, this method of obtaining organic substances by a plant is called air powered .

Photosynthesis is always supported by root nutrition - the absorption of water and mineral salts from the soil. Without water, photosynthesis does not occur.

Green leaf - specialized air supply body. Due to the flat shape of the leaf blade, the leaf has a large surface of contact with the air and sunlight. The presence in the pulp of the leaf of numerous chloroplasts with chlorophyll creates a huge photosynthetic surface, thus turning the leaf into a powerful factory for the formation of organic substances.

The role of light in photosynthesis. Prove that green plant forms organic matter only in the presence of light simple experience. A green plant, such as zonal pelargonium (geranium), is placed in a dark cabinet. After 2-3 days, this plant darkens a small part of one leaf with black paper or foil and put the plant in the light. After 8-10 hours, this sheet is cut off, the darkening plate is removed from it. Then, to bleach the leaf, it is boiled in alcohol (in this case, chlorophyll is destroyed and the green color disappears). After that, the leaf is placed in a solution of iodine. As a result of the experiment, it can be seen that the undarkened part of the leaf, which contained starch, turned blue (starch turns blue from iodine), while the darkened part of the leaf acquired yellow iodine. This indicates that here, in the darkened part of the sheet. no starch was formed because the leaf cells did not receive light energy. Starch is an organic substance that a plant forms in the light during photosynthesis.

Photosynthesis

a process in which a green plant from inorganic substances (carbon dioxide and water) using the energy of sunlight forms organic substances - carbohydrates (glucose, fructose, starch), as well as oxygen.

Club mosses. Horsetails. ferns. the art of plants. horsetail

Modern horsetails - perennial herbaceous plants with a rigid stem and a well-developed underground rhizome. Adventitious roots extend from the rhizome. Articulation of shoots is characteristic. On the stems in the nodes of the whorl of branches and small scaly leaves.

Horsetails (from left to right): spore-bearing and barren stems of field horsetail, forest horsetail, meadow horsetail

Autotrophic nutrition- chlorophyll is found in the chloroplasts of green cells of summer shoots. In the spring, shoots grow on the rhizomes, which end in spore-bearing spikelets. This is where controversy comes in. Ripe spores spill out and, having fallen into favorable conditions, germinate, heterosexual gametophytes are formed - the sexual generation. Fertilization takes place in water.

Development of the asexual generation of horsetail - sporophyte:

– Outgrowth (gametophyte) of sperm + egg cell zygote sporophyte (embryo) of spore outgrowth (gametophyte).

Horsetails grow in fields, forests, or near bodies of water, usually in areas with wet soil(only about 30 species survived). In the fields where horsetails live, the soil needs liming.

Horsetail-fed cows and goats produce more milk. Feed on horsetails and some wild animals - deer and wild boars. At the same time, horsetails are poisonous plants for horses.

In medicine, horsetail preparations are used, which have a versatile and diverse effect. They are used as a diuretic, anti-inflammatory, hemostatic, tonic, wound healing and astringent. They help with heart failure, improve water-salt metabolism. As part of various collections, horsetail is used to treat hypertension, gout and wound healing. The plant is effective for edema of various origins and exudative (wet) pleurisy.

IN folk medicine the field of application of horsetail is the same. In addition, it is believed that horsetail herb helps with certain malignant neoplasms, internal and external bleeding, cholelithiasis and kidney stones.

Plant kingdom. Club clubs

Perennial evergreen, herbaceous plants with erect and creeping shoots, found in coniferous and mixed forests. Descended from psilophytes. Adventitious roots extend from the creeping areas of the shoot along the ground. The leaves are small, of various shapes, arranged alternately on the shoots, opposite or whorled.

Club mosses (from left to right): ram moss, club moss, yearly moss

Vegetative reproduction - due to the death of sections of old shoots and the rooting of viable fragments that give rise to new plants. asexual reproduction carried out by disputes.

Species of club mosses are used as medicinal, dyeing, cosmetic and ornamental plants.

In scientific medicine, spores (usually a club-shaped club) are used - before in Russia they were called lycopodium, or club seed - for the preparation of baby powders, pouring pills. Spores contain up to 50% fatty non-drying oil, alkaloids, phenolic acids, proteins, sugars, mineral salts. Along with the spores of this species, spores of annual and flattened club mosses are used.

Spores are harvested in late summer - early autumn, after the yellowing of the spore-bearing spikelets. Spikelets are cut with scissors or a sharp knife, usually in wet weather, put into bags of dense fabric, then dried in the open air and sieved through a fine sieve to separate the spores.

In folk medicine, mosquito spores are used as a healing agent for filling wounds, burns, frostbite, with eczema, boils, lichen, erysipelas. The stems are used for diseases of the bladder, liver, respiratory organs, urinary incontinence, stomach pain, hemorrhoids, dyspepsia and rheumatism.
Sheep club shoots are used as an emetic, laxative, for the treatment of chronic alcoholism and smoking. The whole plant of the club moss contains the poisonous alkaloid selyagin, so treatment should be carried out under the supervision of a physician.

In cosmetology, club mosses are used for furunculosis and against baldness.

Spores are also used in metallurgy for sprinkling molds during shaped casting - when they are burned, a layer of gases is formed that prevents the product from sticking and gives the metal a smooth surface.

In pyrotechnics, spores are sometimes added to sparklers.

The stems of all types of club moss produce a blue dye suitable for dyeing fabrics.

The processes of respiration and photosynthesis are the "privilege" of the subjects of the plant kingdom. Knowledge about them is one of those mandatory minimums that are required from a student preparing for the exam in biology.

Definition

Breath Plants take in oxygen and release carbon dioxide.

Photosynthesis- This is the process of formation of organic substances using the energy of the sun, carbon dioxide and water, which occurs in the cells of green plants.

Comparison

Respiration is a natural process of gas exchange, which plants, like all living organisms, carry out with external environment. Respiration occurs in all organs of the plant. It is carried out through stomata, lenticels and cracks in the bark of trees.

The breathing process takes place around the clock. The organization of respiration is occupied by special cell organelles - mitochondria.

The difference between respiration and photosynthesis

Photosynthesis is a process that is impossible without sunlight, therefore it occurs only during daylight hours or in the presence of the energy of our star stored earlier by plants. Photosynthesis can only occur in plant cells that contain chloroplasts with the pigment chlorophyll. Traditionally, photosynthesis occurs in leaves while they are green, in stems, in individual parts of a flower, in fruits.

In the process of respiration, plant cells absorb atmospheric oxygen using accumulated organic compounds, specifically starch. In this case, there is a consumption, waste, destruction of organic matter. As a result of respiration, carbon dioxide is released, which returns to the atmosphere, and water, which remains in the middle of a living organism.

During photosynthesis, the plant absorbs carbon dioxide and uses the stored water. Under the influence of the energy of solar quanta, a redox reaction occurs, the result of which is the formation of organic substances (sugars or starch) and the release of oxygen.

Findings site

1. Respiration ensures the life of the plant itself, and the released oxygen and organic substances accumulated as a result of photosynthesis make it possible for heterotrophic organisms to exist on Earth.
2. Respiration occurs in plants constantly, and photosynthesis occurs only under the influence of sunlight.
3. All plant cells are involved in respiration, and only green cells are involved in photosynthesis.
4. Oxygen is taken in during respiration and released during photosynthesis.
5. In respiration, organic substances are broken down, and during photosynthesis they are synthesized.

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 (a predatory species 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 a human, animal or plant population some locality. 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 spatial structure populations - that is, about the features of the placement of individuals in a 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.

Ecological pyramid - graphic image relationships between producers, consumers and decomposers in the 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 an ecosystem, species belonging to these three main groups are in complex relationships and form food chains,

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 organs can be stored in the soil. vegetative propagation, such as rhizomes, which will have an impact on 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 stability.

Biodiversity (biological diversity) is the diversity of life in all its manifestations. In a narrower sense, biodiversity is understood as diversity at three levels of organization: genetic diversity (the diversity of genes and their variants - alleles), diversity of species in ecosystems, and, finally, 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 ecological complexes of which they are a 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). Currently, about 1.7 million species have been described, although there are 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 main reason biodiversity conservation lies in the fact 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 responses 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;

groundwater: 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 more water due to evaporation than it 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 nitrogen is found in nature in a free state. Inorganic nitrogen compounds do not occur in nature in large quantities.

layers on the coast Pacific Ocean 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

living matter plays an important role. 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 others

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 detected by modern research methods directly during operation 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 water, 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.Ion pollution heavy metals interferes with the life 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. IN 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 rain and melt, that is, formed during the melting of snow, ice, hail), as a rule, are discharged through a storm sewer system

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. Main chemical elements contributing to eutrophication - 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 that 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 into the environment natural environment cyanides, arsenic, beryllium compounds; 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. Storage and disposal worn tires are currently still unresolved problems, as this often causes severe fires that are very difficult to extinguish.

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The respiration of plants and animals in biology is a unique and universal process. It acts as an integral property of any organism that inhabits the Earth. Consider further how plant respiration occurs.

Biology

The life of organisms, like any manifestation of their activity, is directly related to energy consumption. Plant respiration, nutrition, organs, photosynthesis, movement and absorption of water and necessary compounds, as well as many functions, are associated with the continuous satisfaction of necessary needs. Organisms need energy. It comes from consumed nutrient compounds. In addition, the body needs plastic substances that serve as a building material for cells. The breakdown of these compounds, which occurs during respiration, is accompanied by the release of energy. It also ensures the satisfaction of vital needs.

Plant growth and respiration

These two processes are closely related to each other. Full respiration of plants ensures the active development of the organism. The process itself is presented as a complex system, including many conjugated redox reactions. In the course of them, the chemical nature of organic compounds changes and the energy present in them is used.

general characteristics

Cellular respiration of plants is an oxidative process that occurs with the participation of oxygen. In the course of it, the decomposition of compounds occurs, which is accompanied by the formation of chemically active products and the release of energy. The overall equation for the whole process looks like this:

С6Н12О6 + 602 > 6С02 + 6Н20 + 2875 kJ/mol

Not all of the energy that is released can be used to support life processes. The body needs mainly that part of it that is concentrated in ATP. In many cases, the synthesis of adenosine triphosphate is preceded by the formation of a difference in electric charges on the membrane. This process is associated with differences in the concentration of hydrogen ions on different sides of it. According to modern data, not only adenosine triphosphate, but also the proton gradient acts as a source of energy to ensure the vital activity of the cell. Both forms can be used to activate the processes of synthesis, intake, movement of nutrients and water, the formation of a potential difference between the external environment and the cytoplasm. The energy that is not stored in ATP and the proton gradient is more dissipated as light or heat. It is useless for the body.

Why is this process needed?

What is the importance of respiration in plants? This process is considered central to the life of the organism. The energy that is released during respiration is used to grow and maintain the already developed parts of the plant in an active state. However, these are far from all the points that determine the importance of this process. Consider the main role of plant respiration. This process, as mentioned above, is a complex redox reaction. It goes through several stages. At intermediate stages, the formation of organic compounds occurs. Subsequently, they are used in various metabolic reactions. Intermediates include pentoses and organic acids. Plant respiration is thus a source of many metabolites. From the overall equation, it can be seen that water is also formed during this process. In conditions of dehydration, it can save the body from death. Generally speaking, respiration is the opposite of photosynthesis. However, in some cases these processes complement each other. They contribute to the supply of both energy equivalents and metabolites. In some cases, when energy is released in the form of heat, plant respiration leads to a useless loss of dry matter. Therefore, an increase in the intensity of this process is far from always beneficial for the body.

Peculiarities

Plant respiration is carried out around the clock. During this process, organisms absorb oxygen from the atmosphere. In addition, they inhale O2, formed in them as a result of photosynthesis and available in the intercellular spaces. During the day, oxygen mainly enters through the stomata of young shoots and leaves, lentils of stems, and also the skin of roots. At night, almost all plants have them covered. During this period, plants use oxygen for respiration, which has accumulated in the intercellular spaces and was formed during photosynthesis. Oxygen entering the cells oxidizes the organic complex compounds present in them, converting them into water and carbon dioxide. In this case, the energy spent on their formation during photosynthesis is released. Carbon dioxide is removed from the body through the cell surface of young roots, lentils, and stomata.

Experiences

To make sure that plant respiration really occurs, you can do the following:

How to use the acquired knowledge?

In the process of growing cultivated plantations, the soil is compacted, and the air content in it is significantly reduced. To improve the flow of life processes, loosening of the soil is carried out. Plants that are grown on waterlogged (highly moistened) soils especially suffer from a lack of oxygen. Improved O2 supply is achieved by draining the land. The dust that settles on the leaves negatively affects the breathing process. Its solid small particles clog the stomata, which greatly complicates the supply of oxygen to the leaves. In addition, impurities that enter the air during combustion at industrial enterprises also have a harmful effect. different kind fuel. In this regard, when landscaping an urban area, as a rule, trees are planted that are resistant to dust. These, for example, include horse chestnut, linden, bird cherry, poplar. During the storage of grain, special attention should be paid to their moisture content. The fact is that with an increase in its level, the intensity of breathing increases. This, in turn, contributes to the fact that the seeds begin to be strongly heated by the released heat. This, in turn, negatively affects the embryos - they die. To avoid such consequences, the seeds that are stored must be dry. The room itself must be well ventilated.

Conclusion

Thus, plant respiration is of great importance for ensuring their normal development at any stage. Without this process, it is impossible not only to ensure the normal functioning of the body, but also the formation of all its sections. During respiration, the most important compounds are formed, without which the existence of a plant is impossible. This complex, multi-stage process is a central link in the entire life of any organism. Knowledge of this contributes to ensuring proper conditions for growing and storing cultivated plants, achieving high yields of grain and other agricultural plantations. It is known that heat is released during respiration. Near some crops, the air temperature can rise by more than 10 degrees. This property is used by a person for various purposes.

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.

A 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. Lear, G. Polster found that in clear sunny days for harvesting, the most productive are the early morning hours, 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?

IN cloudy days the greenhouse involuntarily turns into a dungeon for the 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 the wooden slats and roll it up, lifting it 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 a one-room apartment on the second floor of a 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. To feed plants in 1 liter of hot water, dissolve four teaspoons (with 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 of vegetable crops make it possible to avoid discrepancy between their requirements and 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.