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The purpose of the lesson: To form knowledge about the constituent components of the biological community, about the features of the trophic structure of the community, about food relationships that reflect the path of the circulation of substances, to form the concepts of food chain, food web.
During the classes
1. Organizational moment.
2. Checking and updating knowledge on the topic “Composition and structure of the community”.
On the board: Our world is not an accident, not chaos - there is a system in everything.
Question. What system in nature is referred to in this statement?
Working with terms.
Exercise. Insert missing words.
A community of organisms of different species that are closely interconnected is called …………. . It consists of: plants, animals, …………. , …………. . The totality of living organisms and components of inanimate nature, united by the metabolism and energy on a homogeneous area of the earth's surface, is called …………….. or …………….
Exercise. Choose four components of the ecosystem: bacteria, animals, consumers, fungi, abiotic component, climate, decomposers, plants, producers, water.
Question. How are living organisms in an ecosystem related to each other?
3. Learning new material. Explanation using presentation.
4. Consolidation of new material.
Task number 1. Slide number 20.
Identify and sign: producers, consumers and decomposers. Compare food chains and establish similarities between them. (at the beginning of each chain, plant food, then comes a herbivore, and at the end - a predatory animal). Name the mode of nutrition of plants and animals. (plants are autotrophs, that is, they themselves produce organic matter, animals - heterotrophs - consume ready-made organic matter).
Conclusion: a food chain is a series of organisms that feed on each other in sequence. Food chains begin with autotrophs - green plants.
Task number 2. Compare two food chains, identify similarities and differences.
- Clover - rabbit - wolf
- Plant litter - earthworm - blackbird - hawk - sparrowhawk (The first food chain begins with producers - living plants, the second with plant debris - dead organic matter).
In nature, there are two main types of food chains: pasture (grazing chains), which begin with producers, detrital (decomposition chains), which begin with plant and animal remains, animal excrement.
Conclusion: Therefore, the first food chain is pasture, because. begins with producers, the second - detrital, because. starts with dead organics.
All components of food chains are distributed into trophic levels. The trophic level is a link in the food chain.
Task number 3. Make a food chain, including the listed organisms: caterpillar, cuckoo, tree with leaves, buzzard, soil bacteria. Specify producers, consumers, decomposers. (tree with leaves - caterpillar - cuckoo - buzzard - soil bacteria). Determine how many trophic levels this food chain contains (this chain consists of five links, therefore five - trophic levels). Determine which organisms are located at each trophic level. Make a conclusion.
- The first trophic level is green plants (producers),
- Second trophic level - herbivorous animals (consumers of the 1st order)
- The third trophic level - small predators (consumers of the 2nd order)
- Fourth trophic level - large predators (consumers of the 3rd order)
- Fifth trophic level - organisms that consume dead organic matter - soil bacteria, fungi (decomposers)
In nature, each organism uses not one food source, but several, then in biogeocenoses food chains intertwine and form food web. For any community, it is possible to draw up a diagram of all the food relationships of organisms, and this diagram will look like a network (we will consider an example of a food network in Fig. 62 in the textbook of biology by A.A. Kamensky and others.)
5. Development of the acquired knowledge.
Practical work in groups.
Task number 1. Solving environmental situations
1. In one of the Canadian reserves, all wolves were destroyed in order to increase the herd of deer. Did this achieve the goal? Explain the answer.
2. Hares live in a certain area. Of these, small hares - 100 pieces weighing - 2 kg, and their parents 20 pieces - weighing 5 kg. The mass of 1 fox is 10 kg. Find the number of foxes in this forest. How many plants must grow in the forest for the hares to grow.
3. There are 2000 water rats in a pond with rich vegetation, each rat consumes 80g of plants per day. How many beavers can feed this pond if a beaver consumes an average of 200 g of plant food per day.
4. State the facts given in disorder in a logically correct sequence (in the form of numbers).
1. Nile perch began to eat a lot of herbivorous fish.
2. Having greatly multiplied, the plants began to rot, poisoning the water.
3. Smoking Nile perch required a lot of firewood.
4. In 1960, British colonists launched the Nile perch into the waters of Lake Victoria, which quickly multiplied and grew, reaching a weight of 40 kg and a length of 1.5 m.
5. Forests on the shores of the lake were intensively cut down - therefore, water erosion of the soil began.
6. Dead zones with poisoned water appeared in the lake.
7. The number of herbivorous fish has decreased, and the lake has become overgrown with aquatic plants.
8. Soil erosion has reduced the fertility of fields.
9. Meager soils did not yield crops, and the peasants went bankrupt .
6. Self-examination of the acquired knowledge in the form of a test.
1. Producers of organic matter in an ecosystem
A) producers
B) consumers
B) decomposers
D) predators
2. Which group do microorganisms living in the soil belong to?
A) producers
B) consumers of the first order
C) consumers of the second order
D) decomposers
3. Name the animal that should be included in the food chain: grass -> ... -> wolf
B) hawk
4. Determine the correct food chain
A) hedgehog -> plant -> grasshopper -> frog
B) grasshopper -> plant -> hedgehog -> frog
C) plant -> grasshopper -> frog -> hedgehog
D) hedgehog -> frog -> grasshopper -> plant
5. In the coniferous forest ecosystem, second-order consumers include
A) common spruce
B) forest mice
B) taiga ticks
D) soil bacteria
6. Plants produce organic substances from inorganic substances, therefore they play a role in food chains
A) final link
B) the initial link
B) consumer organisms
D) destructive organisms
7. Bacteria and fungi in the circulation of substances play the role of:
A) producers of organic substances
B) consumers of organic substances
B) destroyers of organic matter
D) destroyers of inorganic substances
8. Determine the correct food chain
A) hawk -> titmouse -> insect larvae -> pine
B) pine tree -> titmouse -> insect larvae -> hawk
C) pine tree -> insect larvae -> titmouse -> hawk
D) insect larvae -> pine tree -> titmouse -> hawk
9. Determine which animal should be included in the food chain: cereals -> ? -> perishing -> kite
A) a frog
D) lark
10. Determine the correct food chain
A) seagull -> perch -> fish fry -> algae
B) algae -> seagull -> perch -> fish fry
C) fish fry -> algae -> perch -> seagull
D) algae -> fish fry -> perch -> seagull
11. Continue the food chain: wheat -> mouse -> ...
B) gopher
B) fox
D) triton
7. General conclusions of the lesson.
Answer the questions:
- How organisms are interconnected in biogeocenosis (food ties)
- What is a food chain (a series of organisms that feed on each other in succession)
- What types of food chains are distinguished (pasture and detrital chains)
- What is the name of the link in the food chain (trophic level)
- What is a food web (intertwining food chains)
In order to answer this question and correctly draw up food chains, you first need to find out what food chains are.
What is a "supply chain"
The food chain is the main relationship of animals, plants, insects to supply themselves with food (or being food). A food chain, or in other words, a food chain, is a series of organisms that feed on each other. That is, each creature feeds on another creature and is itself food for other organisms. Hence the name "chain", that is, sequentially, one after the other, it is a closed system. The chain may include microorganisms, fungi, insects, plants, animals. There is a clear distribution between them - one is food, the other is a consumer. Food chains, both animal and human, usually begin with plants.
Food chains can be made not only on and in soil, but also in water, in the sky, in the forest-steppe, and so on. It may also be that there is an association of different tiers, animals living on these tiers and plants growing on them. For example, an insect that lives on the soil is food for a bird that lives in the air, in the upper tier. That is, it is not necessary that the food chain consists of animals and plants from only one tier.
An example of food chains in soil
Above, we found out what a food chain is. In order to make examples of food chains in the soil, you need to find out who is the inhabitant of the soil, who can participate in these chains.
- Firstly, these are worms, larvae, insects.
- Secondly, these are various microorganisms, decayed plants, tree roots and other growing organisms.
- Thirdly, these are animals, such as a mole, a shrew, a bear and the like.
Knowing the inhabitants of the soil, we can already compose food chains. For example:
- decayed plant remains -> earthworms -> moles -> hedgehogs;
- plant root -> ant larva -> shrews;
- plant root -> beetle -> mole.
Thus, we have compiled three examples of a food chain in soil. Many more similar examples could be made.
Most living organisms eat organic food, this is the specificity of their life on our planet. Among this food are plants, and the meat of other animals, their products of activity and dead matter, ready for decomposition. The very process of nutrition in different species of plants and animals occurs in different ways, but the so-called They always form, they transform matter and energy, and nutrients can thus pass from one creature to another, carrying out the circulation of substances in nature.
In the woods
Forests of various kinds cover quite a lot of land surface. It is the lungs and the instrument of cleansing our planet. It is not for nothing that many progressive modern scientists and activists oppose mass deforestation today. The food chain in the forest can be quite diverse, but, as a rule, includes no more than 3-5 links. In order to understand the essence of the issue, let us turn to the possible components of this chain.
Producers and consumers
- The first are autotrophic organisms that feed on inorganic food. They take energy and matter to create their own bodies, using gases and salts from their environment. An example is green plants that get their nutrition from sunlight through photosynthesis. Or numerous types of microorganisms that live everywhere: in the air, in the soil, in the water. It is the producers that for the most part make up the first link in almost any food chain in the forest (examples will be given below).
- The second are heterotrophic organisms that feed on organic matter. Among them are those of the first order that directly carry out nutrition at the expense of plants and bacteria, producers. The second order - those who eat animal food (predators or carnivores).
Plants
As a rule, the food chain in the forest begins with them. They are the first link in this cycle. Trees and shrubs, grasses and mosses obtain food from inorganic substances using sunlight, gases and minerals. A food chain in a forest, for example, may begin with a birch tree, the bark of which is eaten by a hare, who, in turn, is killed and eaten by a wolf.
herbivorous animals
In a variety of forests, animals that feed on plant foods are found in abundance. Of course, for example, it is very different in its content from the lands of the middle zone. Various species of animals live in the jungle, many of which are herbivores, which means they make up the second link in the food chain, eating plant foods. From elephants and rhinos to barely visible insects, from amphibians and birds to mammals. So, in Brazil, for example, there are more than 700 species of butterflies, almost all of them are herbivores.
Poorer, of course, is the fauna in the forest belt of central Russia. Accordingly, there are much fewer options for the supply chain. Squirrels and hares, other rodents, deer and elk, hares - this is the basis for such chains.
Predators or carnivores
They are called so because they eat flesh, eating the meat of other animals. They occupy a dominant position in the food chain, often being the final link. In our forests, these are foxes and wolves, owls and eagles, sometimes bears (but in general they belong to which they can eat both plant and animal food). In the food chain, both one and several predators can take part, eating each other. The final link, as a rule, is the largest and most powerful carnivore. In the forest of the middle lane, this role can be played, for example, by a wolf. There are not too many such predators, and their population is limited by the food base and energy reserves. Since, according to the law of conservation of energy, when nutrients pass from one link to the next, up to 90% of the resource can be lost. This is probably why the number of links in most food chains cannot exceed five.
Scavengers
They feed on the remains of other organisms. Oddly enough, there are also quite a lot of them in the nature of the forest: from microorganisms and insects to birds and mammals. Many beetles, for example, use the corpses of other insects and even vertebrates as food. And bacteria are able to decompose the dead bodies of mammals in a fairly short time. Scavenging organisms play a huge role in nature. They destroy matter, transforming it into inorganic substances, release energy, using it for their life activity. If it were not for scavengers, then, probably, the entire earthly space would be covered with the bodies of animals and plants that have died for all time.
In the woods
To make a food chain in the forest, you need to know about those inhabitants who live there. And also about what these animals can eat.
- Birch bark - insect larvae - small birds - birds of prey.
- Fallen leaves - bacteria.
- Butterfly caterpillar - mouse - snake - hedgehog - fox.
- Acorn - mouse - fox.
- Cereals - mouse - eagle owl.
There are also more authentic ones: fallen leaves - bacteria - earthworms - mice - mole - hedgehog - fox - wolf. But, as a rule, the number of links is not more than five. The food chain in a spruce forest is slightly different from that in a deciduous forest.
- Cereal seeds - sparrow - wild cat.
- Flowers (nectar) - butterfly - frog - already.
- Fir cone - woodpecker - eagle.
Food chains can sometimes intertwine with each other, forming more complex, multi-level structures that combine into a single forest ecosystem. For example, the fox does not disdain to eat both insects and their larvae and mammals, so several food chains intersect.
Soil is a unique habitat for soil fauna.
This environment is characterized by the absence of sharp fluctuations in temperature and humidity, a variety of organic substances used as a source of nutrition, contains pores and cavities of various sizes, and there is always moisture in it.
Numerous representatives of the soil fauna - invertebrates, vertebrates and protozoa - inhabiting various soil horizons and living on its surface, have a great influence on the processes of soil formation. Soil animals, on the one hand, adapt to the soil environment, modify their shape, structure, and functioning, and, on the other hand, actively influence the soil, changing the structure of the pore space and redistributing organo-mineral substances in the profile along the depth. In the soil biocenosis, complex stable food chains are formed. Most soil animals feed on plants and plant debris, the rest are predators. Each type of soil has its own characteristics of the biocenosis: its structure, biomass, distribution in the profile and functioning parameters.
According to the size of individuals, representatives of the soil fauna are divided into four groups:
- microfauna- organisms less than 0.2 mm (mainly protozoa, nematodes, rhizopods, echinococci living in a moist soil environment);
- mesofauna- animals from 0.2 to 4 mm in size (microarthropods, the smallest insects and specific worms adapted to life in soil with sufficiently humid air);
- macro fauna- animals 4-80 mm in size (earthworms, mollusks, insects - ants, termites, etc.);
- megafauna- animals over 80 mm (large insects, scorpions, moles, snakes, small and large rodents, foxes, badgers and other animals that dig tunnels and burrows in the soil).
According to the degree of connection with the soil, three groups of animals are distinguished: geobionts, geophiles and geoxens. Geobionts animals are called, the entire development cycle of which takes place in the soil (earthworms, springtails, centipedes).
Geophiles- inhabitants of the soil, part of the development cycle of which necessarily takes place in the soil (most insects). Among them, species are distinguished that live in the soil in the larval stage, and leave it in the adult state (beetles, click beetles, centipede mosquitoes, etc.), and necessarily go to the soil for pupation (Colorado potato beetle, etc.).
geoxenes- animals that more or less accidentally go into the soil as a temporary shelter (earthen fleas, harmful turtle, etc.).
For organisms of different sizes, soils provide different types of environment. Microscopic objects (protozoa, rotifers) in the soil remain inhabitants of the aquatic environment. During wet periods, they swim in pores filled with water, as in a pond. Physiologically, they are aquatic organisms. The main features of the soil as a habitat for such organisms are the predominance of wet periods, the dynamics of humidity and temperature, the salt regime, and the size of cavities and pores.
For larger (not microscopic, but small) organisms (mites, springtails, beetles), the habitat in the soil is a set of passages and cavities. Their habitation in the soil is comparable to living in a cave saturated with moisture. Developed porosity, a sufficient level of humidity and temperature, and the content of organic carbon in the soil are important. For large soil animals (earthworms, centipedes, beetle larvae), the entire soil serves as a habitat. For them, the density of addition of the entire profile is important. The shape of the animals reflects the adaptation to locomotion in loose or dense soil.
Among soil animals, invertebrates absolutely predominate. Their total biomass is 1000 times greater than the total vertebrate biomass. According to experts, the biomass of invertebrates in different natural zones varies in a wide range: from 10-70 kg/ha in the tundra and desert to 200 in coniferous forest soils and 250 in steppe soils. Earthworms, centipedes, dipteran and beetle larvae, adult beetles, mollusks, ants, and termites are widely distributed in the soil. Their number per 1 m 2 of forest soil can reach several thousand.
The functions of invertebrates and vertebrates in soil formation are important and varied:
- destruction and grinding of organic residues (increasing their surface hundreds and thousands of times, animals make them available for further destruction by fungi and bacteria), eating organic residues on the surface of the soil and inside it.
- the accumulation of nutrients in the bodies and, mainly, the synthesis of nitrogen-containing protein compounds (after the completion of the animal's life cycle, tissue decay occurs and the substances and energy accumulated in its body return to the soil);
- the movement of masses of soil and soil, the formation of a kind of micro- and nanorelief;
- formation of zoogenic structure and pore space.
An example of an unusually intense impact on the soil is the work of earthworms. On an area of 1 ha, worms annually pass through their intestines in different soil-climatic zones from 50 to 600 tons of fine soil. Together with the mineral mass, a huge amount of organic residues is absorbed and processed. On average, during the year, worms produce excrement (coprolites) of about 25 t/ha.
In order to answer this question and correctly draw up food chains, you first need to find out what food chains are.
What is a "supply chain"
The food chain is the main relationship of animals, plants, insects to supply themselves with food (or being food). A food chain, or in other words, a food chain, is a series of organisms that feed on each other. That is, each creature feeds on another creature and is itself food for other organisms. Hence the name "chain", that is, sequentially, one after the other, it is a closed system. The chain may include microorganisms, fungi, insects, plants, animals. There is a clear distribution between them - one is food, the other is a consumer. Food chains, both animal and human, usually begin with plants.
Food chains can be made not only on and in soil, but also in water, in the sky, in the forest-steppe, and so on. It may also be that there is an association of different tiers, animals living on these tiers and plants growing on them. For example, an insect that lives on the soil is food for a bird that lives in the air, in the upper tier. That is, it is not necessary that the food chain consists of animals and plants from only one tier.
An example of food chains in soil
Above, we found out what a food chain is. In order to make examples of food chains in the soil, you need to find out who is the inhabitant of the soil, who can participate in these chains.
- Firstly, these are worms, larvae, insects.
- Secondly, these are various microorganisms, decayed plants, tree roots and other growing organisms.
- Thirdly, these are animals, such as a mole, a shrew, a bear and the like.
Knowing the inhabitants of the soil, we can already compose food chains. For example:
- decayed plant remains -> earthworms -> moles -> hedgehogs;
- plant root -> ant larva -> shrews;
- plant root -> beetle -> mole.
Thus, we have compiled three examples of a food chain in soil. Many more similar examples could be made.
