The one percent rule. According to the one percent rule, a change in the energy of a natural system within 1% takes the natural system out of an equilibrium (quasi-stationary) state. All large-scale phenomena on the Earth's surface (powerful cyclones, volcanic eruptions, the process of global photosynthesis), as a rule, have a total energy that does not exceed 1% of the energy of solar radiation incident on the surface of our planet. The artificial introduction of energy into the biosphere should not exceed this limit. The transition of the process energy beyond this value (1%) usually leads to significant anomalies: sharp climatic deviations, changes in the nature of vegetation, large forest and steppe fires.

Ten percent rule (law of the energy pyramid). In accordance with the law of the energy pyramid, on average no more than 10% of energy moves from one trophic level of the ecological pyramid to another level.

Trophic level is the totality of all living organisms belonging to one link in the food chain. The first trophic level is always producers, creators of organic substances necessary for all living organisms. Herbivorous consumers (phytotrophs or phytophages) belong to the second trophic level; carnivores (predators), living off phytophages, belong to the third trophic level; those consuming other carnivores are accordingly classified as fourth, etc.

Green plants, consuming solar energy and inorganic substances from the external environment, form organic substances through photosynthesis, i.e. produce biological products, which are often called primary production or gross production of producers. Secondary products are biomass created by consumers.

In the process of their life, plants spend part of their primary production on respiration, on the formation of new cells and tissues, and on growth. If we subtract from primary production those products that producers spent for their needs, then the remaining part represents what is called “net production.” Net production is in the form of biomass and moves continuously from one trophic level to another. Pure primary production, captured by consumers in the form of food, is also spent by them on life processes and on the construction of secondary products, i.e. biomass of phytophages), and part returns to the abiatic environment in the form of excrement, secretions and corpses. In turn, approximately 10% of the biomass and energy stored in phytophages are transferred to the next level of consumers, ensuring their existence, diversity and abundance.

The law of the energy pyramid allows you to make calculations of the required land area to provide the population with food and other environmental and economic calculations.

The average maximum transfer of energy (or matter in energy terms) from one trophic level of the ecological pyramid to another is 10%, and can range from 7 to 17%. This value does not lead to adverse consequences for the ecosystem and therefore can be accepted as the norm for environmental management in human economic activity. Exceeding this value is unacceptable, since in this case complete disappearances of populations may occur. The law of the energy pyramid and the ten percent rule serve as a general limitation in the use of natural resources for human economic activity.

The rule of mandatory filling of ecological niches. An empty ecological niche is always naturally filled. An ecological niche as a functional place of a species in an ecosystem allows a form capable of developing adaptive characteristics to fill this niche, but sometimes this requires considerable time.

Note. A likely example of the rule for mandatory completion of environmental information is the emergence of new diseases, for example, AIDS (acquired immunodeficiency syndrome). It was hypothetically predicted more than 10 years before the disease was identified as an influenza-like virus with a high mortality rate. The basis for the prediction was that the victory over many human infectious diseases freed up ecological niches that inevitably had to be filled. Since during ecological duplication, as a rule, the change goes in the direction from larger and highly organized forms to smaller and more organized ones, it was assumed that one of the ecological niches would be filled precisely by a virus with a high degree of variability. Thus, the hypothesis was apparently justified.

The rule of inevitable chain reactions (“hard” control of nature). “Hard” technical management of natural systems and processes is fraught with natural chain reactions, a significant part of which is environmentally, socially and economically unacceptable over a long period of time. An example with the Aral disaster. The transfer of water from northern rivers would lead to undesirable environmental effects (flooding of a huge area of ​​land, destruction of forest, oil, gas fields, etc.)

The rule of “soft” management of nature.“Soft” (indirect) control of nature causes chain reactions that are desirable for humans.

“Soft” control is more preferable than a “hard” technogenic solution, despite the high initial costs. This is the rule for the expedient transformation of nature. In contrast to “hard” management (see the Rule of chain reactions under “hard” management), “soft” management, based on restoring the former natural productivity of ecosystems or increasing it through a purposeful series of events based on the use of objective laws of nature, makes it possible to direct natural chain reactions reactions in a direction favorable for the economy and people’s lives. An example is a comparison of two forms of forestry management - clear-cutting (“hard” impact) and selective logging (“soft” impact). Clear cutting, in which all the wood is taken in one go, is considered economically more profitable. When selective cutting occurs, many technical complications arise, and therefore the cost of wood harvesting turns out to be more expensive. It is assumed that in clear cutting areas the forest can and should be restored by mass planting (and this activity is generally inexpensive). However, with clear cuttings, the forest environment itself is gradually lost, which leads to a drop in river levels, in other places - to waterlogging, overgrowing of the cutting area with non-forest plant species, preventing forest growth, the emergence of breeding grounds for forest pests, and other adverse consequences. The lower initial costs of a “hard” event give rise to a chain of damages, which then require large expenses for their elimination. On the contrary, with selective logging, forest restoration is facilitated due to the preservation of the forest environment. The increased initial costs are gradually recouped by preventing environmental damage.

The transition from “soft” to “hard” management is advisable only with the simultaneous replacement of extensive forms of farming with extremely intensive ones and, as a rule, within relatively short time intervals. In the long term, only “soft” control of natural processes is effective. See also Principles of Nature Transformation.

The rule is “environmentally-economical”. Economics and ecology cannot be opposed. You cannot slow down the pace of industrialization - this will mean a kind of economic utopianism, just as you cannot reduce your efforts in the field of ecology - this will mean environmental extremism. The solution to the issue lies somewhere in the middle.

Integral resource rule. Competing in the field of use specific natural systems of economic sectors inevitably cause damage to each other the more strongly, the more significantly they change the jointly exploited environmental component or all ecosystem generally. For example, in the water sector, hydropower, transport, public utilities, irrigated agriculture and the fishing industry are interconnected in such a way that fisheries are in the least advantageous position. The more complete the hydropower use of water, the more difficult it is to manage other sectors of the water economy: the development of water transport complicates other ways of using water, and irrigation causes difficulties in related forms of water exploitation.

Demographic saturation rule. In a global or regionally isolated population, the population size corresponds to the maximum ability to support its life activity, including all aspects of existing human needs.

In essence, this rule states that a person, like any other biological species, will increase its number to the maximum possible size, which is determined by the capacity of the environment, and no more. However, humanity creates pressure on the environment not so much biologically as technogenically. In fact, what is currently observed in the world is not demographic saturation, taking into account all human needs, but technical oversaturation. Failure to comply with the rule of demographic saturation results in a sharp imbalance in the system of relationships between man and nature. Theoretically, a situation is possible when limiting mechanisms are implemented and a demographic catastrophe occurs (a sharp decline in the human population).

The discipline “Ecology” examines the principles of managing natural and natural-anthropogenic systems in the process of environmental management in order to ensure the sustainable development of these systems. To do this, first of all, it is necessary to know and take into account the rules, principles and laws of the functioning of the biosphere.

Rules

The one percent rule. According to the one percent rule, a change in the energy of a natural system within 1% (from a few tenths to, as an exception, a few percent) takes the natural system out of an equilibrium (quasi-stationary) state. All large-scale phenomena on the Earth's surface (powerful cyclones, volcanic eruptions, the process of global photosynthesis), as a rule, have a total energy that does not exceed 1% of the energy of solar radiation incident on the surface of our planet. The transition of the process energy beyond this value (1%) usually leads to significant anomalies: sharp climatic deviations, changes in the nature of vegetation, large forest and steppe fires.

Note. The One Percent Rule is of particular importance for global systems. Their energy, apparently, fundamentally cannot exceed the level of approximately 0.2% of incoming solar radiation (the energy level of photosynthesis) without catastrophic consequences. This is probably an insurmountable threshold and limit for humanity (from which “nuclear winter” follows).

The Ten Percent Rule (Law of the Pyramid of Energy) . In accordance with the law of the energy pyramid, on average no more than 10% of energy moves from one trophic level of the ecological pyramid to another level. The law of the energy pyramid allows you to make calculations of the required land area to provide the population with food and other environmental and economic calculations.

The average maximum transfer of energy (or matter in energy terms) from one trophic level of the ecological pyramid to another is 10% (10% rule); it can range from 7 to 17%. This value does not lead to adverse consequences for the ecosystem and therefore can be accepted as the norm for environmental management in human economic activity. Exceeding this value is unacceptable, since in this case

complete extinctions of populations may occur. The law of the energy pyramid and the ten percent rule serve as a general limitation in the use of natural resources for human economic activity.

The rule of mandatory filling of ecological niches. An empty ecological niche is always naturally filled. An ecological niche as a functional place of a species in an ecosystem allows a form capable of developing adaptive characteristics to fill this niche, but sometimes this requires considerable time.

Often, so-called ecological niches are just an optical illusion (for specialists). In reality, ecological niches are sometimes filled in the most unexpected ways.

In connection with the possibility of the existence of pseudo-empty ecological niches, one should never rush to conclusions about the possibility of filling these niches through acclimatization of species, since acclimatization and re-acclimatization work will be effective only if there are actually free ecological niches, which is extremely rare.

Note. A likely example of the rule of mandatory filling of ecological niches is the emergence of new diseases, for example, AIDS (acquired immunodeficiency syndrome). It was hypothetically predicted more than 10 years before the disease was identified as an influenza-like virus with a high mortality rate. The basis for the prediction was that the victory over many human infectious diseases freed up ecological niches that inevitably had to be filled. Since during ecological duplication, as a rule, the change goes in the direction from larger and highly organized forms to smaller and more organized ones, it was assumed that one of the ecological niches would be filled precisely by a virus with a high degree of variability. The influenza virus has a mutation rate of 1:10 5 with an average normal process frequency of 1:10 6 . The AIDS virus is even more variable - it has a mutation rate of 1:10 4 . Thus, the hypothesis was apparently justified.

The rule of inevitable chain reactions (“hard” control of nature). “Hard” technical management of natural systems and processes is fraught with natural chain reactions, a significant part of which is environmentally, socially and economically unacceptable over a long period of time. An example with the Aral disaster. The transfer of water from northern rivers would lead to undesirable environmental effects (flooding of a huge area of ​​land, destruction of forest, oil, gas fields, etc.)

The rule of “soft” management of nature. “Soft” (indirect) control of nature causes chain reactions that are desirable for humans.

“Soft” control is more preferable than a “hard” technogenic solution, despite the high initial costs. This is the rule for the expedient transformation of nature. In contrast to “hard” management (see the Rule of chain reactions under “hard” management), “soft” management, based on restoring the former natural productivity of ecosystems or increasing it through a purposeful series of events based on the use of objective laws of nature, makes it possible to direct natural chain reactions reactions in a direction favorable for the economy and people’s lives. An example is the comparison of two forms of forestry management – ​​clear-cutting (“hard” impact) and selective logging (“soft” impact). Clear cutting, in which all the wood is taken in one go, is considered economically more profitable. When selective cutting occurs, many technical complications arise, and therefore the cost of wood harvesting turns out to be more expensive. It is assumed that in clear cutting areas the forest can and should be restored by mass planting (and this activity is generally inexpensive). However, with clear cuttings, the forest environment itself is gradually lost, which leads to a drop in river levels, in other places - to waterlogging, overgrowing of the cutting area with non-forest plant species, preventing forest growth, the emergence of breeding grounds for forest pests, and other adverse consequences. The lower initial costs of a “hard” event give rise to a chain of damages, which then require large expenses for their elimination. On the contrary, with selective logging, forest restoration is facilitated due to the preservation of the forest environment. The increased initial costs are gradually recouped by preventing environmental damage.

The transition from “soft” to “hard” management is advisable only with the simultaneous replacement of extensive forms of farming with extremely intensive ones and, as a rule, within relatively short time intervals. In the long term, only “soft” control of natural processes is effective. See also Principles of Nature Transformation.

Rule “Ecologically-economical”. Economics and ecology cannot be opposed. You cannot slow down the pace of industrialization - this will mean a kind of economic utopianism, just as you cannot reduce your efforts in the field of ecology - this will mean environmental extremism. The solution to the issue lies somewhere in the middle.

Rule of economic-ecological perception. We cannot mean that the number of degrees of freedom in the actions of our descendants will decrease rather than increase. We live on credit from our grandchildren. Descendants will pay very dearly for nature's bills, much more than we pay.

The rule of basal metabolism, about the advantage of spending matter and energy on the self-maintenance of the system. The ratio between basal metabolism and useful work in the human economy can be improved to a certain extent, like any efficiency. For mechanical systems it can be very high, although it never reaches 100%; the efficiency of complex dynamic systems can only reach relatively high values ​​for a short time, but not more than 30%. The rest goes to internal exchange, otherwise the systems themselves would not exist. Long-lived large-scale ecosystems cannot be equated with short-lived mechanical systems. In living systems, a lot of “fuel” is spent on “repairs” for self-maintenance and self-regulation, and when calculating the efficiency of engines, energy costs for repairs, etc. are not taken into account.

Integral resource rule. Competing in the field of use specific natural systems of economic sectors inevitably cause damage to each other the more strongly, the more significantly they change the jointly exploited ecologicalcomponent or all ecosystem generally. The integral resource rule is another applied consequence of the law of internal dynamic equilibrium. For example, in the water sector, hydropower, transport, public utilities, irrigated agriculture and the fishing industry are interconnected in such a way that fisheries are in the least advantageous position. The more complete the hydropower use of water, the more difficult it is to manage other sectors of the water economy: the development of water transport complicates other methods of water use, and irrigation causes difficulties in related forms of water exploitation.

Rule of demographic saturation. In a global or regionally isolated population, the population size corresponds to the maximum ability to support its life activity, including all aspects of existing human needs.

In essence, this rule states that a person, like any other biological species, will increase its number to the maximum possible size, which is determined by the capacity of the environment, and no more. However, humanity creates pressure on the environment not so much biologically as technogenically. In fact, what is currently observed in the world is not demographic saturation, taking into account all human needs, but technical oversaturation.

Failure to comply with the demographic rule

saturation results in a sharp imbalance in the system of relationships “man-nature”. Theoretically, a situation is possible when limiting mechanisms are implemented and a demographic catastrophe occurs (a sharp decline in the human population). The rule of historical growth of production due to succession ecosystem rejuvenation. Since the net productivity of a community is maximum in the early stages of ecosystem development, the main source of production growth during the historical development of society was the successional rejuvenation of ecosystems.

(Succession is the replacement of one community of organisms (biocenoses) by others in a certain sequence).

The net productivity of the community (annual increase in biomass) is high in the early stages of development and is practically zero in mature ecosystems. Initially, successionally mature ecosystems were the basis for gathering and hunting. From a certain point they begin to give way to production cenoses. In the latter, the yield of pure products is higher. Previously, as the population grew, the area of ​​rejuvenated systems increased, an extensive way of developing agricultural production. Next, the following mechanism for increasing the productivity of the ecosystem is activated: the intensive path of development is an increase in the amount of energy invested in production. However, this mechanism is not unlimited. There comes a time when additional investment of energy into the agroecosystem leads to its destruction, as the energy limit is reached. The modern historical finale of this development is the transition to the exploitation of extremely rejuvenated ecosystems with a sharp jump in energy costs. Ecosystem methods of doping through successional rejuvenation are almost exhausted. further investment of anthropogenic energy in agriculture will lead to the destruction of natural structures, so other technologies will be required - more efficient and low-energy-intensive. The more rapidly a person’s environment and farming conditions change under the influence of anthropogenic factors, the sooner, according to the feedback principle, a change occurs in the socio-ecological properties of a person, the economic and technical development of society. This system tends to self-accelerate.

For example, in response to deteriorating indicators of the living environment caused by anthropogenic activities, mechanisms arise that seek to improve it (change of generations of technology, resource-saving knowledge-intensive production, demographic regulation). The only question is to what extent the acceleration of historical development will correspond in action to the rule of demographic saturation and the Le Chatelier-Brown principle.

So far, historical development is clearly lagging behind and this poses a danger to people’s well-being.

32.Energy flow in an ecosystem. The 10% energy rule.

Nutrition is the main way of movement of substances and energy.

Organisms in an ecosystem are connected by a commonality of energy and nutrients that are necessary to sustain life. The main source of energy for the vast majority of living organisms on Earth is the Sun. Photosynthetic organisms (green plants, cyanobacteria, some bacteria) directly use the energy of sunlight. In this case, complex organic substances are formed from carbon dioxide and water, in which part of the solar energy is accumulated in the form of chemical energy. Organic substances serve as a source of energy not only for the plant itself, but also for other organisms in the ecosystem. The release of energy contained in food occurs during the process of breathing. Respiration products - carbon dioxide, water and inorganic substances - can be reused by green plants. As a result, substances in this ecosystem undergo an endless cycle. At the same time, the energy contained in food does not cycle, but gradually turns into thermal energy and leaves the ecosystem. Therefore, a necessary condition for the existence of an ecosystem is a constant flow of energy from outside.

In 1942, the American ecologist R. Lindeman formulated the law of the energy pyramid (the law of 10 percent), according to which, on average, about 10% of the energy received at the previous level of the ecological pyramid passes from one trophic level through food chains to another trophic level. The rest of the energy is lost in the form of thermal radiation, movement, etc. As a result of metabolic processes, organisms lose about 90% of all energy in each link of the food chain, which is spent on maintaining their vital functions.

If a hare ate 10 kg of plant matter, then its own weight may increase by 1 kg. A fox or wolf, eating 1 kg of hare meat, increases its mass by only 100 g. In woody plants, this proportion is much lower due to the fact that wood is poorly absorbed by organisms. For grasses and seaweeds, this value is much greater, since they do not have difficult-to-digest tissues. However, the general pattern of the process of energy transfer remains: much less energy passes through the upper trophic levels than through the lower ones.

Let's consider the transformation of energy in an ecosystem using the example of a simple pasture trophic chain, in which there are only three trophic levels.

level - herbaceous plants,

level - herbivorous mammals, for example, hares

level - predatory mammals, for example, foxes

Nutrients are created during the process of photosynthesis by plants, which form organic substances and oxygen, as well as ATP, from inorganic substances (water, carbon dioxide, mineral salts, etc.) using the energy of sunlight. Part of the electromagnetic energy of solar radiation is converted into the energy of chemical bonds of synthesized organic substances.

All organic matter created during photosynthesis is called gross primary production (GPP). Part of the energy of gross primary production is spent on respiration, resulting in the formation of net primary production (NPP), which is the very substance that enters the second trophic level and is used by hares.

Let the runway be 200 conventional units of energy, and the costs of plants for respiration (R) - 50%, i.e. 100 conventional units of energy. Then net primary production will be equal to: NPP = WPP - R (100 = 200 - 100), i.e. At the second trophic level, the hares will receive 100 conventional units of energy.

However, for various reasons, hares are able to consume only a certain share of NPP (otherwise the resources for the development of living matter would disappear), while a significant part of it is in the form of dead organic remains (underground parts of plants, hard wood of stems, branches, etc. .) is not capable of being eaten by hares. It enters detrital food chains and/or is decomposed by decomposers (F). The other part goes to the construction of new cells (population size, growth of hares - P) and ensuring energy metabolism or respiration (R).

In this case, according to the balance approach, the balance equality of energy consumption (C) will look like this: C = P + R + F, i.e. The energy received at the second trophic level will be spent, according to Lindemann's law, on population growth - P - 10%, the remaining 90% will be spent on respiration and removal of undigested food.

Thus, in ecosystems, with an increase in the trophic level, there is a rapid decrease in the energy accumulated in the bodies of living organisms. From here it is clear why each subsequent level will always be less than the previous one and why food chains usually cannot have more than 3-5 (rarely 6) links, and ecological pyramids cannot consist of a large number of floors: to the final link of the food chain is the same as to the top floor of the ecological pyramid will receive so little energy that it will not be enough if the number of organisms increases.

Such a sequence and subordination of groups of organisms connected in the form of trophic levels represents the flows of matter and energy in the biogeocenosis, the basis of its functional organization.

12.7. Energy flow in ecosystems

Maintaining the vital activity of organisms and the circulation of matter in ecosystems, i.e., the existence of ecosystems, depends on the constant flow of energy necessary for all organisms for their vital activity and self-reproduction (Fig. 12.19).

Rice. 12.19. Energy flow in an ecosystem (according to F. Ramad, 1981)

Unlike substances that continuously circulate through different blocks of the ecosystem, which can always be reused and enter the cycle, energy can be used only once, i.e., there is a linear flow of energy through the ecosystem.

The one-way influx of energy as a universal natural phenomenon occurs as a result of the laws of thermodynamics. First law states that energy can be converted from one form (such as light) to another (such as the potential energy of food), but cannot be created or destroyed. Second Law states that there cannot be a single process associated with the transformation of energy without losing some of it. A certain amount of energy in such transformations is dissipated into inaccessible thermal energy and is therefore lost. Hence, there cannot be transformations of, for example, food substances into the substance that makes up the body of the organism, which occur with 100 percent efficiency.

Thus, living organisms are energy converters. And every time energy is converted, part of it is lost in the form of heat. Ultimately, all the energy entering the biotic cycle of an ecosystem is dissipated as heat. Living organisms do not actually use heat as an energy source to do work - they use light and chemical energy.

Food chains and networks, trophic levels. Within an ecosystem, energy-containing substances are created by autotrophic organisms and serve as food for heterotrophs. Food connections are mechanisms for transferring energy from one organism to another.

A typical example: an animal eats plants. This animal, in turn, can be eaten by another animal. In this way, energy can be transferred through a number of organisms - each subsequent one feeds on the previous one, which supplies it with raw materials and energy (Fig. 12.20).

Rice. 12.20. Biotic cycle of substances: food chain

(according to A.G. Bannikov et al., 1985)

This sequence of energy transfer is called food (trophic) chain, or power circuit. The location of each link in the food chain is trophic level. The first trophic level, as noted earlier, is occupied by autotrophs, or so-called primary producers. Organisms of the second trophic level are called primary consumers, third - secondary consumers etc.

There are generally three types of food chains. The predator food chain begins with plants and moves from small organisms to increasingly larger organisms. On land, food chains consist of three to four links.

One of the simplest food chains looks like (see Fig. 12.5):

plant -> hare -> wolf

producer -> herbivore -> carnivore

The following food chains are also widespread:

plant material (eg nectar) -> fly -> spider ->

rosebush juice -> aphids -> ladybug ->

-> spider -> insectivorous bird -> bird of prey.

In aquatic and, in particular, marine ecosystems, predator food chains tend to be longer than in terrestrial ones. The type of food relationships shown in Fig. 1 is widespread. 12.21 and table. 12.5.

Rice. 12.21. Food chains in terrestrial and aquatic ecosystems:

I - producers; II - herbivores; III, IV, V - carnivores; 0 - destructors (from F. Ramada, 1981)

Structure of the food chain in a marine ecosystem

(after F. Ramad, 1981)

These types of food chains begin with photosynthetic organisms and are called pasture(or consumption chains, or consumption chains).

The third type of food chain, starting with dead plant remains, carcasses and animal excrement, is referred to as detrital(saprophytic) food chains or to detrital chains of decomposition. Deciduous forests play an important role in the detrital food chains of terrestrial ecosystems, most of the foliage of which is not consumed by herbivores and is part of the litter of fallen leaves. The leaves are crushed by numerous detritivores - fungi, bacteria, insects (for example, collembola), etc., and then ingested by earthworms, which uniformly distribute humus in the surface layer of the earth, forming the so-called mull (Fig. 12.22).

Rice. 12.22. Detrital food chain in a terrestrial ecosystem

(after B. Nebel, 1993)

At this level, mushrooms develop mycelium. The decomposing microorganisms that complete the chain produce the final mineralization of dead organic matter. In general, typical detrital food chains of our forests can be represented as follows:

In the food chain diagrams discussed, each organism is represented as feeding on other organisms of one type. The actual food connections in an ecosystem are much more complex, since an animal can feed on organisms of different types from the same food chain or from different food chains, for example, predators of the upper trophic levels. Animals often feed on both plants and other animals. They are called omnivores. Thus, all three types of food chains always coexist in an ecosystem so that its representatives are united by numerous intersecting food connections, and together they form a food chain. (trophic) network(rice . 12.23).

Food webs in ecosystems are very complex, and we can conclude that the energy entering them takes a long time to migrate from one organism to another.

Rice. 12.23. Food web and direction of matter flow

(according to E. A. Kriksunov et al., 1995)

Ecological pyramids. Within each ecosystem, food webs have a well-defined structure, which is characterized by the nature and number of organisms represented at each level of the various food chains. To study the relationships between organisms in an ecosystem and to depict them graphically, they usually use ecological pyramids rather than food web diagrams. Ecological pyramids express the trophic structure of an ecosystem in geometric form. They are constructed in the form of rectangles of the same width, but the length of the rectangles must be proportional to the value of the object being measured. From here you can get pyramids of numbers, biomass and energy.

Ecological pyramids reflect the fundamental characteristics of any biocenosis when they show its trophic structure:

Their height is proportional to the length of the food chain in question, i.e., the number of trophic levels it contains;

Their shape more or less reflects the efficiency of energy transformations during the transition from one level to another.

Pyramids of numbers. They represent the simplest approximation to the study of the trophic structure of an ecosystem. In this case, the number of organisms in a given territory is first counted, grouped by trophic levels and presented in the form of a rectangle, the length (or area) of which is proportional to the number of organisms living in a given area (or in a given volume, if it is an aquatic ecosystem). A basic rule has been established that in any environment there are more plants than animals, more herbivores than carnivores, more insects than birds, etc. (Figure 12.24).

Rice. 12.24. Simplified diagram of a population pyramid

(according to G. A. Novikov, 1979)

Population pyramids reflect the density of organisms at each trophic level. There is great diversity in the construction of various population pyramids. They are often inverted (Fig. 12.25).

For example, in a forest there are significantly fewer trees (primary producers) than insects (herbivores).

Rice. 12.25. Pyramids of numbers:

1 - straight; 2 - inverted (according to E. A. Kriksunov et al., 1995)

Biomass pyramid. Reflects more fully the food relationships in the ecosystem, since it takes into account the total mass of organisms (biomass) each trophic level. The rectangles in the biomass pyramids represent the mass of organisms at each trophic level per unit area or volume. The shape of the biomass pyramid is often similar to the shape of the population pyramid. A characteristic decrease in biomass at each successive trophic level (Fig. 12.26 and 12.27).

Rice. 12.27. Types of biomass pyramids in different divisions

biosphere (according to N.F. Reimers, 1990)

Pyramids of biomass, as well as numbers, can be not only straight, but also inverted. Inverted pyramids of biomass are characteristic of aquatic ecosystems, in which primary producers, such as phytoplanktonic algae, divide very quickly, and their consumers - zooplanktonic crustaceans - are much larger but have a long reproduction cycle. In particular, this applies to freshwater environments, where primary productivity is provided by microscopic organisms whose metabolic rates are increased, i.e., biomass is low, productivity is high.

Pyramid of energy. The most fundamental way to display connections between organisms at different trophic levels are energy pyramids. They represent the energy conversion efficiency and productivity of food chains and are constructed by counting the amount of energy (kcal) accumulated per unit surface area per unit time and used by organisms at each trophic level. Thus, it is relatively easy to determine the amount of energy stored in biomass, but it is more difficult to estimate the total amount of energy absorbed at each trophic level. Having constructed a graph (Fig. 12.28), we can state that destructors, the importance of which seems small in the biomass pyramid, and vice versa in the population pyramid; receive a significant portion of the energy passing through the ecosystem. Moreover, only part of all this energy remains in organisms at each trophic level of the ecosystem and is stored in biomass; the rest is used to satisfy the metabolic needs of living beings: maintaining existence, growth, reproduction. Animals also expend a significant amount of energy for muscular work.

Rice. 12.28. Ecological pyramids (according to E. Odum, 1959):

a - population pyramid; b - biomass pyramid;

c - pyramid of energy.

The shaded rectangles indicate net production.

Let's take a closer look at what happens to energy when it is transferred through the food chain (Fig. 12.29).

Rice. 12.29. Flow of energy through three trophic levels

chains (according to P. Duvigneau and M. Tang, 1968)

It was previously noted that solar energy received by a plant is only partially used in the process of photosynthesis. The energy fixed in carbohydrates represents the gross production of the ecosystem (P in). Carbohydrates are used to build protoplasm and plant growth. Part of their energy is spent on breathing (D 1). Net production (P h) is determined by the formula:

Consequently, the flow of energy passing through the level of producers, or gross output, can be represented:

A certain amount of substances created by producers serves as food for phytophages. The rest eventually dies and is processed by decomposers (H). The food (A) assimilated by phytophages is only partially used for the formation of their biomass (Pd). It is mainly spent on providing energy for breathing processes (D) and, to a certain extent, is excreted from the body in the form of secretions and excrement (E). The flow of energy through the second trophic level is expressed as follows:

Second-order consumers (predators) do not destroy the entire biomass of their victims. Moreover, of the amount that they destroy, only a part is used to create biomass of their own trophic level. The rest is mainly spent on breathing energy and is excreted with excrement and excrement. The flow of energy passing through the level of second-order consumers (carnivores) is expressed by the formula:

In a similar way, the entire food chain can be traced to the last trophic level. By vertically distributing the various energy costs at trophic levels, we obtain a complete picture of the food pyramid in the ecosystem (Fig. 12.30).

Rice. 12.30. Pyramid of Energy (from F. Ramada, 1981):

E - energy released with metabolites; D - natural deaths; W - feces; R - breathing

The flow of energy, expressed by the amount of assimilated substance along the food chain, at each trophic level decreases or:

R. Lindeman first formulated in 1942 energy pyramid law, which in textbooks is often called the “law of 10%”. According to this law, from one trophic level of the ecological pyramid On average, no more than 10% of the energy passes to another level.

Only 10-20% of the initial energy is transferred to subsequent heterotrophs. Using the law of the energy pyramid, it is easy to calculate that the amount of energy reaching tertiary carnivores (trophic level V) is about 0.0001 of the energy absorbed by producers. It follows that the transfer of energy from one level to another occurs with very low efficiency. This explains the limited number of links in the food chain, regardless of a particular biocenosis.

E. Odum (1959) in an extremely simplified food chain - alfalfa -> calf -> child assessed the transformation of energy and illustrated the magnitude of its losses. Let’s say, he reasoned, there is alfalfa planted on an area of ​​4 hectares. There are calves feeding in this field (supposed to eat only alfalfa) and a 12-year-old boy eating exclusively veal. The calculation results, presented in the form of three pyramids: numbers, biomass and energy (Fig. 12.31 and 12.32), indicate; that alfalfa uses only 0.24% of all solar energy falling on the field, the calf absorbs 8% of this product, and only 0.7% of the calf’s biomass ensures the development of the child during the year*.

Rice. 12.31. Simplified ecosystem: alfalfa - calves - boy

(according to E. Odum, 1959):

A - pyramid of numbers; B - biomass pyramid; B - pyramid of energy

E. Odum, thus, showed that only one millionth of the incident solar energy is converted into carnivore biomass, in this case contributing to an increase in the child’s weight, and the rest is lost and dissipated in a degraded form in the environment. The above example clearly illustrates the very low ecological efficiency of ecosystems and the low efficiency of transformation in food chains. We can state the following: if 1000 kcal (day m2) is fixed by producers, then 10 kcal (day m2) goes into the biomass of herbivores and only 1 kcal (day m2) goes into the biomass of carnivores.

Since a certain amount of a substance can be used by each biocenosis repeatedly, and a portion of energy once, it is more appropriate to say that a cascade transfer of energy occurs in the ecosystem (see Fig. 12.19).

Consumers serve as a manager and stabilizing link in the ecosystem (Fig. 12.32). Consumers generate a spectrum of diversity in the cenosis, preventing the monopoly of dominants. Rule of control value of consumers can rightfully be considered quite fundamental. According to cybernetic views, the control system should be more complex in structure than the controlled one, then the reason for the multiplicity of consumer types becomes clear. The controlling significance of consumers also has an energetic basis. The flow of energy through one or another trophic level cannot be absolutely determined by the availability of food in the underlying trophic level. As is known, there is always a sufficient “reserve” left, since the complete destruction of food would lead to the death of consumers. These general patterns are observed within the framework of population processes, communities, levels of the ecological pyramid, and biocenoses as a whole.

* If a boy ate only veal for a year, this would require 4.5 calves, and to feed them 2'10 7 alfalfa plants are needed.

Trophic Levels, Types, Meaning, Patterns and Food Chain Definition

What is a food chain?

Every organism must receive energy to live. For example, plants consume energy from the sun, animals eat plants, and some animals eat other animals.

A food chain is the sequence of who eats whom in a biological community (ecosystem) to obtain nutrients and energy that support life.

Autotrophs (producers)

Autotrophs- living organisms that make their own food, that is, their own organic compounds, from simple molecules such as carbon dioxide. There are two main types of autotrophs:

• Chemoautotrophs obtain organic substances due to chemical reactions that involve inorganic compounds (hydrogen, hydrogen sulfide, ammonia, etc.). This process is called chemosynthesis.

Autotrophs are the basis of every ecosystem on the planet. They make up the majority of food chains and webs, and the energy obtained through photosynthesis or chemosynthesis supports all other organisms in ecological systems. When it comes to their role in food chains, autotrophs can be called producers or producers.

Heterotrophs (consumers)

Heterotrophs, also known as consumers, cannot use solar or chemical energy to produce their own food from carbon dioxide. Instead, heterotrophs obtain energy by consuming other organisms or their byproducts. People, animals, fungi and many bacteria are heterotrophs. Their role in food chains is to consume other living organisms. There are many species of heterotrophs with different ecological roles, from insects and plants to predators and fungi.

Destructors (reducers)

Another consumer group should be mentioned, although it does not always appear in food chain diagrams. This group consists of decomposers, organisms that process dead organic matter and waste, turning them into inorganic compounds.

Decomposers are sometimes considered a separate trophic level. As a group, they feed on dead organisms coming from various trophic levels. (For example, they are able to process decaying plant matter, the body of a squirrel malnourished by predators, or the remains of a deceased eagle.) In a sense, the trophic level of decomposers runs parallel to the standard hierarchy of primary, secondary, and tertiary consumers. Fungi and bacteria are key decomposers in many ecosystems.

Decomposers, as part of the food chain, play an important role in maintaining a healthy ecosystem because they return nutrients and moisture to the soil, which are then used by producers.

Levels of the food (trophic) chain

Diagram of levels of the food (trophic) chain

A food chain is a linear sequence of organisms that transfer nutrients and energy from producers to top predators.

The trophic level of an organism is the position it occupies in the food chain.

First trophic level

The food chain starts with autotrophic organism or producer, producing its own food from a primary energy source, usually solar or energy from hydrothermal vents at mid-ocean ridges. For example, photosynthetic plants, chemosynthetic bacteria and archaea.

Second trophic level

Next come the organisms that feed on autotrophs. These organisms are called herbivores or primary consumers and consume green plants. Examples include insects, hares, sheep, caterpillars and even cows.

Third trophic level

The next link in the food chain are animals that eat herbivores - they are called secondary consumers or carnivorous (predatory) animals(for example, a snake that feeds on hares or rodents).

Fourth trophic level

In turn, these animals are eaten by larger predators - tertiary consumers(for example, an owl eats snakes).

Fifth trophic level

Tertiary consumers are eaten quaternary consumers(for example, a hawk eats owls).

Every food chain ends with an apex predator or superpredator - an animal with no natural enemies (eg crocodile, polar bear, shark, etc.). They are the “masters” of their ecosystems.

When any organism dies, it is eventually eaten by detritivores (such as hyenas, vultures, worms, crabs, etc.) and the rest is decomposed by decomposers (mainly bacteria and fungi), and energy exchange continues.

Arrows in a food chain show the flow of energy, from the sun or hydrothermal vents to top predators. As energy flows from body to body, it is lost at each link in the chain. The collection of many food chains is called food web.

The position of some organisms in the food chain may vary because their diet is different. For example, when a bear eats berries, it acts as a herbivore. When it eats a plant-eating rodent, it becomes a primary predator. When a bear eats salmon, it acts as a superpredator (this is due to the fact that salmon is the primary predator because it feeds on herring, which eats zooplankton, which feeds on phytoplankton, which generate their own energy from sunlight). Think about how people's place in the food chain changes, even often within a single meal.

Types of food chains

In nature, as a rule, there are two types of food chains: pasture and detritus.

Grassland food chain

Grassland food chain diagram

This type of food chain begins with living green plants to feed the herbivores on which carnivores feed. Ecosystems with this type of circuit are directly dependent on solar energy.

Thus, the grazing type of food chain depends on the autotrophic capture of energy and its movement along the links of the chain. Most ecosystems in nature follow this type of food chain.

Examples of grazing food chains:

Detrital food chain

Detrital food chain diagram

This type of food chain begins with decaying organic material - detritus - which is consumed by detritivores. Then, predators feed on detritivores. Thus, such food chains are less dependent on direct solar energy than grazing ones. The main thing for them is the influx of organic substances produced in another system.

For example, this type of food chain is found in the decaying litter of temperate forests.

Energy in the food chain

Energy is transferred between trophic levels when one organism feeds on and receives nutrients from another. However, this movement of energy is inefficient, and this inefficiency limits the length of food chains.

When energy enters a trophic level, some of it is stored as biomass, as part of the body of organisms. This energy is available for the next trophic level. Typically, only about 10% of the energy that is stored as biomass at one trophic level is stored as biomass at the next level.

This principle of partial energy transfer limits the length of food chains, which typically have 3-6 levels.

At each level, energy is lost in the form of heat, as well as in the form of waste and dead matter that decomposers use.

Why does so much energy leave the food web between one trophic level and the next? Here are some of the main reasons for inefficient energy transfer:

• At each trophic level, a significant portion of energy is dissipated as heat as organisms perform cellular respiration and move about in daily life.
• Some organic molecules that organisms feed on cannot be digested and are excreted as feces.
• Not all individual organisms in a trophic level will be eaten by organisms from the next level. Instead, they die without being eaten.
• Feces and uneaten dead organisms become food for decomposers, who metabolize them and convert them into their energy.

So, none of the energy actually disappears - it all ends up producing heat.

Food chain meaning

1. Food chain studies help understand feeding relationships and interactions between organisms in any ecosystem.

2. Thanks to them, it is possible to evaluate the mechanism of energy flow and the circulation of substances in the ecosystem, as well as understand the movement of toxic substances in the ecosystem.

3. Studying the food chain provides insight into biomagnification issues.

In any food chain, energy is lost every time one organism is consumed by another. Due to this, there should be many more plants than herbivores. There are more autotrophs than heterotrophs, and therefore most of them are herbivores rather than carnivores. Although there is intense competition between animals, they are all interconnected. When one species goes extinct, it can affect many other species and have unpredictable consequences.

Rule 10 of Food Chain Energy

More precisely, a pattern in the field of biology established Raymond Lindeman, according to which only part (approximately 10%) of the energy received at a certain system level is transferred to organisms located at higher levels.

For example, plants can absorb up to 1% solar energy. In turn, herbivores consume about 10% plant energy (or: up to 90% the energy accumulated by plants is simply lost...).

Predators, feeding on herbivorous animals, receive 10% of the energy contained in the biomass of everything they eat.

The reverse flow associated with the consumption of substances and energy produced by the upper level of the ecological pyramid by its lower levels, for example, from animals to plants, is much weaker - no more 0,5% from its general flow, and therefore we can assume that the energy cycle does not occur in the biocenosis.

EXAMPLE. “...a person gnawing a carrot is a consumer of the first order, but having tasted such a French dish as frog legs, he becomes a consumer of the third order. Most herbivores, carnivores and omnivores draw food from several chains that make up their food web.”

Lucien Mathieu, Let's save the earth, M., Progress, 1985, p. 23.

EXAMPLE.“The predator lives on the flesh of the animals it eats. It plucks grass fifteen hours a day and digests it around the clock - and he eats enough for three days in a quarter of an hour. This is a more efficient way of consuming energy: quickly, a lot, already converted from plants. It’s like a Snickers: you eat it and you’re done. The predator as an improved biological system, indirectly, through a “filter-enrichment”, working on the energy of substances in the earth’s crust and on solar energy. He himself cannot eat grass, he will die, but he must live. Likewise, the government system strives to obtain energy in the most efficient manner available to it. If it’s faster and easier to take from someone else than to do it yourself, we take it away. And this does not always take the form of robbery. Ideologically and morally, this can be dressed in a variety of clothes.”

Weller M.I., Kassandra, St. Petersburg, “Password”, 2003, p. 80-81.

CONTROL WORK IN BIOLOGY for the first half of the year

In 11th grade (2016 – 2017 academic year)

On a fragment of one DNA strand, the nucleotides are arranged in the following sequence: A-A-G-T-C-T-A-C-G-T-A-G.

a) Complete the diagram of the structure of a double-stranded DNA molecule

Answer:______________________________________________

b) What principle underlies the structure of the DNA molecule?

c) What is the length in nanometers of this DNA fragment?

Answer:________________________________________________

In peas, the red color of the flowers dominates over the white, and the tall growth dominates over the dwarf one. Traits are inherited independently. When two plants with red flowers were crossed, one of which was tall and the other short, the resulting plants were 35 tall with red flowers, 32 short with red flowers, 10 tall with white flowers and 13 short with white flowers.

What are the genotypes of the parents?

Answer:_______________________________________________

Establish the sequence of systematic groups of animals, starting with the smallest
A) Common fox
B) Chordates
B) Predatory
D) Mammals
D) Foxes
E) Wolf

In DNA, the share of nucleotides with adenine accounts for 15%. Determine the percentage of nucleotides containing cytosine that make up the molecule.Using Chargaff's rule, which describes the quantitative relationships between different types of nitrogenous bases in DNA (G + T = A + C), calculate the percentage of nucleotides with cytosine in this sample.

Write down only the corresponding number in your answer.

Answer: ___________________________%.

5. Establish the sequence of systematic plant taxa, starting with the largest taxon. Write down the corresponding sequence of numbers in the table.

1) Meadow bluegrass

2) Bluegrass

3) Angiosperms

4) Monocots

5) Plants

6) Cereals

6. Analyze the graph of the reproduction rate of lactic acid bacteria.

Select statements that can be formulated based on the analysis of the results obtained.

Bacterial reproduction rate

1) always directly proportional to the change in ambient temperature

2) depends on the resources of the environment in which the bacteria are located

3) depends on the genetic program of the organism

4) increases at a temperature of 20–36 °C

5) decreases at temperatures above 36 °C

Write down in your answer the numbers under which the selected statements are indicated.

Answer: ___________________________

7. Bergmann's rule states that among related forms of warm-blooded animals leading a similar lifestyle, those that live in areas with prevailing low temperatures tend to have larger body sizes compared to the inhabitants of warmer zones and regions.

Look at the photographs showing representatives of three closely related species of mammals. Arrange these animals in the sequence in which their natural habitats are located on the surface of the Earth from north to south.

Write down in the table the corresponding sequence of numbers that indicate the photographs.

1. brown bear 2. 3. kodiak

Answer:

2. Using your knowledge of thermoregulation, explain Bergmann's rule.

Answer:__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

8.

1. Look at the image of a eukaryotic cell organelle. What is it called?

Answer:___________________________

What process will be disrupted in the cell in the event of damage (impaired functioning) of this organelle?

Answer: _______________________________________

Determine the origin of the diseases listed. Write down the number of each disease on the list in the appropriate cell of the table. Several numbers can be written in table cells.

List of human diseases:

1) measles

2) hemophilia

3) phenylketonuria

4) tuberculosis

5) cerebral stroke

Acquired disease

Infectious

Non-infectious

10. Anton came to the doctor because he was feeling unwell. The doctor gave him a referral for analysis, the results of which showed that the number of leukocytes was 7.2 × 113, while the norm is 4–9 × 109. What test did the doctor suggest and what diagnosis did he make based on the results obtained?

Select the answers from the following list and write their numbers in the table.

List of answers:

1) pneumonia

2) anemia

3) blood test

4) decreased immunity

5) stool analysis

Answer:

Diagnosis

11.

The genetic code is a method of encoding a sequence of amino acid residues in proteins using a sequence of nucleotides in a nucleic acid, characteristic of all living organisms.

The table shows three types of bases (first, second and third), please note that they are given in two versions: without brackets - RNA nucleotides, and in brackets - DNA nucleotides.

Study the genetic code table, which demonstrates the correspondence of amino acid residues to the composition of codons.

Using the amino acid glycine (GLY) as an example, explain the following property of the genetic code: the code is triplet.

Genetic code table

Answer_____________________________________________________________________________________________________________________________________________________________________________________________________________________________________

1. Sort organisms according to their position in the food chain. In each cell, write the name of one of the proposed organisms.

Pelist of organisms: cruciferous flea beetles, polecat, snake, turnip leaves, frog

Food chain:

2 . The rule states: “no more than 10% of the energy flows from each previous trophic level to the next.” Using this rule, calculate the amount of energy (in kJ) that goes to the level of first-order consumers when the net annual primary production of the ecosystem is 10,000 kJ.

Answer___________________________________________________________________

Fill in the blank cells of the table using the list of missing elements below: for each gap indicated by a letter, select and write down the number of the required element in the table.

Science studying this level

Example

______________________(A)

Biochemistry

______________________(B)

Biogeocenotic

______________________(IN)

______________________(G)

______________________(D)

E)

Lungs

Missing elements:

1) anatomy

2) organismic

3) ecology

4) RNA

5) molecular genetic

6) biogeocenosis

14. The court was considering a claim to establish the paternity of the child. A woman withIblood type a child was born withIblood group. Will the court satisfy the claim against L. M, who hasIVblood type?

Analyze the table data and answer the questions.

I(0)

II(A)

III(B)

IV(AB)

Mother's blood type

I(0)

I(0)

II(A) I(0)

III(B) I(0)

II(A) III(B)

Child's blood type

II(A)

II(A) I(0)

II(A) I(0)

Any

II(A), III(B) IV(AB)

III(B)I

III(B) I(0)

Any

III(B) I(0)

II(A), III(B) IV(AB)

IV(AB)

II(A) III(B)

II(A), III(B) IV(AB)

II(A), III(B) IV(AB)

II(A), III(B) IV(AB)

The child’s mother stated in court that the father of her son is L.M. with IV (AB) blood group. Could he be the child's father?

Answer: ________________________________________________________________________

2 . Based on the rules of blood transfusion, decide whether the child can donate blood to his mother.

3) Using table data"Blood groups according to the AB0 system" explain your decision.

Red blood cell antigens

Plasma antibodies

α, β

A β

III

In α

A, B

A, B

*Note.

Antigen - any substance that the body considers as foreign or potentially dangerous and against which it usually begins to produce its own antibodies.

Antibodies - blood plasma proteins formed in response to the introduction of bacteria, viruses, protein toxins and other antigens into the human body.

Answer:_________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

15 . . Cholesterol plays an important role in metabolism and the functioning of the nervous system. It enters the body from animal products. Their content in plant products is insignificant. The amount of cholesterol entering the body with food should not exceed 0.3–0.5 g per day.

1. Using the table data, calculate the amount of cholesterol in the breakfast of a person who ate 100 g of low-fat cottage cheese, 25 g of “Dutch” cheese, 20 g of butter and two sausages.

Products

Amount of cholesterol, g/100 g of product

Pasteurized milk

0,01

Sausages (one sausage – 40 g)

0,05

Low-fat cottage cheese

0,04

Sausage

0,08

Cheese "Russian"

0,52

Chicken egg (one egg – 50 g)

0,57

Butter

0,18

Pollock

0,03

What danger does excess cholesterol in the human body pose to human health?

Answer: _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

16 . The picture shows a stegocephalus, an extinct animal that lived 300 million years ago.

Using a fragment of a geochronological table, establish the era and period in which this organism lived, as well as its possible ancestor at the class (superorder) level of animals.

ANSWERS:

A) T-T-C-A-G-A-T-G-C-A-T-C

B) the principle of complementarity

B) 4.08

2. Parental genotypes: AaBv, Aavv

3. d, a, f, c, d, b

4. 35%

5. 5,3,4,6,1,2

1) 1,4,5

1) 2,3.1

2) The essence of the rule:Heat production (heat release by body cells) is proportional to body volume. Heat transfer (heat loss, its transfer to the environment) is proportional to the surface area of ​​the body. As volume increases, the surface area increases relatively slowly, which makes it possible to increase the heat production/heat transfer ratio and thus compensate for heat loss from the body surface in cold climates.

1) Biosynthesis and transport of proteins in the cell.

2) Violation of plastic metabolism or assimilation, or metabolism in the cell.

1. GTT, GTC, CCA, CCG, CCT, CCC.

12 . 1) turnips - cruciferous flea beetles - frog-polecat.

2) 1000

13.

5 – A biochemistry 4 – B;

Biogeocenotic 3 – V 6 – D

– D 1–E lungs

14.

1) answer to the first question: will not happen, since this couple cannot have a child withIblood group.

2) answer to the second question: Maybe

3) answer to the third question : Red blood cells may not stick together.

15.

Answer to the first question: 1.04 g

Answer to the second question : damage to blood vessels or the development of atherosclerosis, or coronary heart disease.

16. Response elements:

Paleozoic era

Period: Carboniferous

Possible ancestor: fish or lobe-finned fish.

Answer criteria:

3 points

1 point

2 points no errors, 1 point an error was made

1 point

1 point

2 points no errors, 1 point an error was made

2 points

2 points no errors, 1 point an error was made

2 points no errors, 1 point an error was made

1 point

3 points no errors; 2 points one mistake was made; 1 point for 2 mistakes, 0 points for 3 or more mistakes.

2 points

1 point

2 points the answer includes all the elements mentioned above; 1 point – the answer includes 2 of the above elements, 0 points – the answer includes 1 of the above elements, or the answer is incorrect

Maximum points: 30 points

At “5” - 25 – 30 points

At “4” - 18 – 24 points

At “3” - 13 – 17 points

At “2” 12 points or less.