Introduction
1. Food chains and trophic levels
2. Food webs
3. Freshwater food connections
4. Forest food connections
5. Energy losses in power circuits
6. Ecological pyramids
6.1 Pyramids of numbers
6.2 Biomass pyramids
Conclusion
Bibliography
Introduction
Organisms in nature are connected by a commonality of energy and nutrients. The entire ecosystem can be likened to a single mechanism that consumes energy and nutrients to do work. Nutrients initially originate from the abiotic component of the system, to which they are ultimately returned either as waste products or after the death and destruction of organisms.
Within an ecosystem, energy-containing organic substances are created by autotrophic organisms and serve as food (a source of matter and energy) for heterotrophs. Typical example: An animal eats plants. This animal, in turn, can be eaten by another animal, and in this way energy can be transferred through a number of organisms - each subsequent one feeds on the previous one, supplying it with raw materials and energy. This sequence is called a food chain, and each link is called a trophic level.
The purpose of the essay is to characterize food connections in nature.
1. Food chains and trophic levels
Biogeocenoses are very complex. They always have many parallel and complexly intertwined power circuits, and total number species are often measured in hundreds and even thousands. Almost always different types They feed on several different objects and themselves serve as food for several members of the ecosystem. The result is a complex network of food connections.
Each link in the food chain is called a trophic level. The first trophic level is occupied by autotrophs, or the so-called primary producers. Organisms of the second trophic level are called primary consumers, the third - secondary consumers, etc. There are usually four or five trophic levels and rarely more than six.
The primary producers are autotrophic organisms, mainly green plants. Some prokaryotes, namely blue-green algae and a few species of bacteria, also photosynthesize, but their contribution is relatively small. Photosynthetics convert solar energy (light energy) into chemical energy contained in organic molecules, from which fabrics are constructed. Chemosynthetic bacteria, which extract energy from inorganic compounds, also make a small contribution to the production of organic matter.
In aquatic ecosystems, the main producers are algae - often small single-celled organisms that make up the phytoplankton of the surface layers of oceans and lakes. On the land most Primary production is supplied by more highly organized forms related to gymnosperms and angiosperms. They form forests and meadows.
Primary consumers feed on primary producers, i.e. they are herbivores. On land, typical herbivores include many insects, reptiles, birds and mammals. Most important groups herbivorous mammals are rodents and ungulates. The latter include grazing animals such as horses, sheep, large cattle, adapted for running on the tips of the fingers.
In aquatic ecosystems (freshwater and marine), herbivorous forms are usually represented by mollusks and small crustaceans. Most of these organisms—cladocerans, copepods, crab larvae, barnacles, and bivalves (such as mussels and oysters)—feed by filtering tiny primary producers from the water. Together with protozoa, many of them form the bulk of the zooplankton that feed on phytoplankton. Life in oceans and lakes depends almost entirely on plankton, since almost all food chains begin with them.
Plant material (e.g. nectar) → fly → spider →
→ shrew → owl
Rosebush sap → aphid → ladybug→ spider → insectivorous bird → bird of prey
There are two main types food chains– pasture and detritus. Above were examples of pasture chains in which the first trophic level is occupied by green plants, the second by pasture animals and the third by predators. The bodies of dead plants and animals still contain energy and " construction material”, as well as intravital excretions, such as urine and feces. These organic materials are decomposed by microorganisms, namely fungi and bacteria, living as saprophytes on organic residues. Such organisms are called decomposers. They release digestive enzymes onto dead bodies or waste products and absorb the products of their digestion. The rate of decomposition may vary. Organic matter urine, feces and animal carcasses are consumed within a few weeks, while fallen trees and the branches can take many years to decompose. A very significant role in the decomposition of wood (and other plant debris) is played by fungi, which secrete the enzyme cellulose, which softens the wood, and this allows small animals to penetrate and absorb the softened material.
Pieces of partially decomposed material are called detritus, and many small animals (detritivores) feed on them, speeding up the decomposition process. Since both true decomposers (fungi and bacteria) and detritivores (animals) are involved in this process, both are sometimes called decomposers, although in reality this term refers only to saprophytic organisms.
Larger organisms can, in turn, feed on detritivores, and then a different type of food chain is created - a chain, a chain starting with detritus:
Detritus → detritivore → predator
Detritivores of forest and coastal communities include earthworm, woodlice, carrion fly larva (forest), polychaete, scarlet fly, holothurian (coastal zone).
Here are two typical detrital food chains in our forests:
Leaf litter → Earthworm → Blackbird → Sparrowhawk
Dead animal → Carrion fly larvae → Grass frog → Common grass snake
Some typical detritivores are earthworms, woodlice, bipeds and smaller ones (<0,5 мм) животные, такие, как клещи, ногохвостки, нематоды и черви-энхитреиды.
2. Food webs
In food chain diagrams, each organism is represented as feeding on other organisms of one type. However, actual food relationships in an ecosystem are much more complex, since an animal may feed on different types of organisms from the same food chain or even from different food chains. This is especially true for predators of the upper trophic levels. Some animals eat both other animals and plants; they are called omnivores (this is the case, in particular, with humans). In reality, food chains are intertwined in such a way that a food (trophic) web is formed. A food web diagram can only show a few of the many possible connections, and it usually includes only one or two predators from each of the upper trophic levels. Such diagrams illustrate nutritional relationships between organisms in an ecosystem and provide the basis for quantitative studies of ecological pyramids and ecosystem productivity.
3. Freshwater food connections
The food chains of a fresh water body consist of several successive links. For example, protozoa, which are eaten by small crustaceans, feed on plant debris and the bacteria that develop on them. The crustaceans, in turn, serve as food for fish, and the latter can be eaten by predatory fish. Almost all species do not feed on one type of food, but use different food objects. Food chains are intricately intertwined. An important general conclusion follows from this: if any member of the biogeocenosis falls out, then the system is not disrupted, since other food sources are used. The greater the species diversity, the more stable the system.
The primary source of energy in aquatic biogeocenosis, as in most ecological systems, is sunlight, thanks to which plants synthesize organic matter. Obviously, the biomass of all animals existing in a reservoir completely depends on the biological productivity of plants.
Often the reason for the low productivity of natural reservoirs is a lack of minerals (especially nitrogen and phosphorus) necessary for the growth of autotrophic plants, or unfavorable acidity of the water. The application of mineral fertilizers, and in the case of an acidic environment, liming of reservoirs, contributes to the proliferation of plant plankton, which feeds animals that serve as food for fish. In this way, the productivity of fishery ponds is increased.
4. Forest food connections
The richness and diversity of plants, which produce enormous amounts of organic matter that can be used as food, cause the development in oak forests of numerous consumers from the animal world, from protozoa to higher vertebrates - birds and mammals.
Food chains in the forest are intertwined into a very complex food web, so the loss of one species of animal usually does not significantly disrupt the entire system. The importance of different groups of animals in biogeocenosis is not the same. The disappearance, for example, in most of our oak forests of all large herbivorous ungulates: bison, deer, roe deer, elk - would have little effect on the overall ecosystem, since their numbers, and therefore biomass, have never been large and did not play a significant role in the general cycle of substances . But if herbivorous insects disappeared, the consequences would be very serious, since insects perform the important function of pollinators in biogeocenosis, participate in the destruction of litter and serve as the basis for the existence of many subsequent links in food chains.
Of great importance in the life of the forest are the processes of decomposition and mineralization of the mass of dying leaves, wood, animal remains and products of their vital activity. Of the total annual increase in biomass of above-ground parts of plants, about 3-4 tons per 1 hectare naturally dies and falls, forming the so-called forest litter. A significant mass also consists of dead underground parts of plants. With litter, most of the minerals and nitrogen consumed by plants return to the soil.
Animal remains are very quickly destroyed by carrion beetles, leather beetles, carrion fly larvae and other insects, as well as putrefactive bacteria. Fiber and other durable substances, which make up a significant part of plant litter, are more difficult to decompose. But they also serve as food for a number of organisms, such as fungi and bacteria, which have special enzymes that break down fiber and other substances into easily digestible sugars.
As soon as plants die, their substance is completely used by destroyers. A significant part of the biomass is made up of earthworms, which do a tremendous job of decomposing and moving organic matter in the soil. The total number of insects, oribatid mites, worms and other invertebrates reaches many tens and even hundreds of millions per hectare. The role of bacteria and lower, saprophytic fungi is especially important in the decomposition of litter.
5. Energy losses in power circuits
All species that form the food chain exist on organic matter created by green plants. In this case, there is an important pattern associated with the efficiency of use and conversion of energy in the nutrition process. Its essence is as follows.
In total, only about 1% of the radiant energy of the Sun falling on a plant is converted into potential energy of chemical bonds of synthesized organic substances and can be further used by heterotrophic organisms for nutrition. When an animal eats a plant, most of the energy contained in the food is spent on various vital processes, turning into heat and dissipating. Only 5-20% of food energy passes into the newly built substance of the animal’s body. If a predator eats a herbivore, then again most of the energy contained in the food is lost. Due to such large losses of useful energy, food chains cannot be very long: they usually consist of no more than 3-5 links (food levels).
The amount of plant matter that serves as the basis of the food chain is always several times greater than the total mass of herbivorous animals, and the mass of each of the subsequent links in the food chain also decreases. This very important pattern is called the rule of the ecological pyramid.
6. Ecological pyramids
6.1 Pyramids of numbers
To study the relationships between organisms in an ecosystem and to graphically represent these relationships, it is more convenient to use ecological pyramids rather than food web diagrams. In this case, the number of different organisms in a given territory is first counted, grouping them by trophic levels. After such calculations, it becomes obvious that the number of animals progressively decreases during the transition from the second trophic level to subsequent ones. The number of plants at the first trophic level also often exceeds the number of animals that make up the second level. This can be depicted as a pyramid of numbers.
For convenience, the number of organisms at a given trophic level can be represented as 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). The figure shows a population pyramid reflecting the real situation in nature. Predators located at the highest trophic level are called final predators.
When sampling - in other words, at a given point in time - the so-called standing biomass, or standing yield, is always determined. It is important to understand that this value does not contain any information about the rate of biomass production (productivity) or its consumption; otherwise errors may occur for two reasons:
1. If the rate of biomass consumption (loss due to consumption) approximately corresponds to the rate of its formation, then the standing crop does not necessarily indicate productivity, i.e. about the amount of energy and matter moving from one trophic level to another over a given period of time, for example, a year. For example, a fertile, intensively used pasture may have lower standing grass yields and higher productivity than a less fertile but little used pasture.
2. Small-sized producers, such as algae, are characterized by a high renewal rate, i.e. high growth and reproduction rates, balanced by their intensive consumption as food by other organisms and natural death. Thus, although standing biomass may be small compared to large producers (such as trees), productivity may not be less because trees accumulate biomass over a long period of time. In other words, phytoplankton with the same productivity as a tree will have much less biomass, although it could support the same mass of animals. In general, populations of large and long-lived plants and animals have a lower renewal rate compared to small and short-lived ones and accumulate matter and energy over a longer period of time. Zooplankton have greater biomass than the phytoplankton on which they feed. This is typical for planktonic communities of lakes and seas at certain times of the year; The biomass of phytoplankton exceeds the biomass of zooplankton during the spring “blooming”, but in other periods the opposite relationship is possible. Such apparent anomalies can be avoided by using energy pyramids.
Conclusion
Completing the work on the abstract, we can draw the following conclusions. A functional system that includes a community of living beings and their habitat is called an ecological system (or ecosystem). In such a system, connections between its components arise primarily on a food basis. A food chain indicates the path of movement of organic matter, as well as the energy and inorganic nutrients it contains.
In ecological systems, in the process of evolution, chains of interconnected species have developed that successively extract materials and energy from the original food substance. This sequence is called a food chain, and each link is called a trophic level. The first trophic level is occupied by autotrophic organisms, or so-called primary producers. Organisms of the second trophic level are called primary consumers, the third - secondary consumers, etc. The last level is usually occupied by decomposers or detritivores.
Food connections in an ecosystem are not straightforward, since the components of the ecosystem are in complex interactions with each other.
Bibliography
1. Amos W.H. The living world of rivers. - L.: Gidrometeoizdat, 1986. - 240 p.
2. Biological encyclopedic dictionary. - M.: Soviet Encyclopedia, 1986. - 832 p.
3. Ricklefs R. Fundamentals of General Ecology. - M.: Mir, 1979. - 424 p.
4. Spurr S.G., Barnes B.V. Forest ecology. - M.: Timber Industry, 1984. - 480 p.
5. Stadnitsky G.V., Rodionov A.I. Ecology. - M.: Higher School, 1988. - 272 p.
6. Yablokov A.V. Population biology. - M.: Higher School, 1987. -304 p.
All living beings on our planet are connected to each other by one of the strongest connections - food. That is, someone is food for someone else, or, in scientific terms, a food source. Herbivores eat plants, the herbivores themselves are eaten by predators, which in turn can also be eaten by other, larger and stronger predators. In biology, these peculiar food connections are usually called food chains. Understanding how the food chain ecosystem works gives biologists an understanding of the various nuances of living organisms, helps explain the behavior of some animals, and understands where the legs come from for certain habits of our four-legged friends.
Types of power circuits
In general, there are two main types of food chains: the grazing chain (also known as the grazing food chain) and the detrital food chain, which is also called the decomposition chain.
Pastoral food chain
The pasture food chain is generally simple and understandable; its essence is briefly described at the beginning of the article: plants serve as food for herbivores and in scientific terminology are called producers. Herbivores that eat plants are called consumers (from Latin this word is translated as “consumers”) of the first order. Small predators are consumers of the second order, and larger ones are of the third order. In nature, there are also longer food chains, numbering five or more links, these are found mainly in the oceans, where larger (and voracious) fish eat smaller ones, which in turn eat even smaller ones, and so on down to algae. The links in the food chain are closed by a special happy link, which no longer serves as food for anyone. Usually this is a person, of course, provided that he is careful and does not try to swim with sharks or walk with lions)). But seriously, such a closing link of nutrition in biology is called a decomposer.
Detrital food chain
But here everything happens a little the other way around, namely, the energy flow of the food chain goes in the opposite direction: large animals, whether predators or herbivores, die and decompose, their remains feed on smaller animals, various scavengers (for example, hyenas), which in their turn also die and decompose, and their mortal remains similarly serve as food, either for even smaller lovers of carrion (for example, some species of ants), or for various special microorganisms. Microorganisms, processing the remains, release a special substance called detritus, hence the name of this food chain.
A more visual diagram of the power circuit is shown in the picture.
What does the length of the power circuit mean?
Studying the length of the food chain gives scientists answers to many questions, for example, how favorable the environment is for animals. The more favorable the habitat, the longer the natural food chain will be due to the abundance of different animals serving each other as food. But the longest food chain is for fish and other inhabitants of the ocean depths.
What is the basis of the food chain?
The basis of any food chain is food connections and energy, which is transferred with the consumption of one representative of the fauna (or flora) to another. Thanks to the energy received, consumers can continue their life activities, but in turn they also become dependent on their food (feed supply). For example, when the famous migration of lemmings occurs, serving as food for various arctic predators: foxes, owls, there is a reduction in the population of not only the lemmings themselves (who die en masse during these same migrations) but also the predators that feed on lemmings, and some of them even migrate with them.
Power circuits, video film
And in addition, we offer you an educational video about the importance of food chains in biology.
The transfer of energy by living organisms eating each other is called a food chain. These are specific relationships between plants, fungi, animals, and microorganisms that ensure the circulation of substances in nature. Also called a food chain.
Structure
All organisms feed, i.e. receive energy that powers life processes. The trophic chain system is formed by links. A link in the food chain is a group of living organisms connected to a neighboring group through the “food-consumer” relationship. Some organisms are food for other organisms, which in turn are also food for a third group of organisms.
There are three types of links:
- producers - autotrophs;
- consumers - heterotrophs;
- decomposers (destructors) - saprotrophs.
Rice. 1. Links in the food chain.
All three links form one chain. There can be several consumers (consumers of the first, second order, etc.). The basis of the chain can be producers or decomposers.
Producers include plants that convert organic substances with the help of light into organic substances, which, when eaten by plants, enter the body of the first-order consumer. The main characteristic of the consumer is heterotrophy. At the same time, consumers can consume both living organisms and dead ones (carrion).
Examples of consumers:
- herbivores - hare, cow, mouse;
- predators - leopard, owl, walrus;
- scavengers - vulture, Tasmanian devil, jackal.
Some consumers, including humans, occupy an intermediate position, being omnivores. Such animals can act as consumers of the first, second and even third order. For example, a bear eats berries and small rodents, i.e. is simultaneously a consumer of the first and second orders.
Reducers include:
- mushrooms;
- bacteria;
- protozoa;
- worms;
- insect larvae.
Rice. 2. Decomposers.
Decomposers feed on the remains of living organisms and their metabolic products, returning inorganic substances to the soil that producers consume.
Kinds
Food chains can be of two types:
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- pasture (grazing chain);
- detrital (decomposition chain).
Pasture chains are characteristic of meadows, fields, seas, and reservoirs. The beginning of the grazing chain is autotrophic organisms - photosynthetic plants.
Next, the chain links are arranged as follows:
- First-order consumers are herbivores;
- second-order consumers are predators;
- third-order consumers are larger predators;
- decomposers.
In marine and oceanic ecosystems, grazing chains are longer than on land. They may include up to five consumer orders. The basis of marine chains is photosynthetic phytoplankton.
The following links are formed by several consumers:
- zooplankton (crustaceans);
- small fish(sprats);
- large predatory fish (herring);
- large predatory mammals (seals);
- apex predators (killer whales);
- decomposers.
Detritus chains are characteristic of forests and savannas. The chain begins with decomposers that feed on organic remains (detritus) and are called detriophages. These include microorganisms, insects, and worms. All these living organisms become food for top predators, for example, birds, hedgehogs, and lizards.
Examples of two types of food chains:
- pasture : clover - hare - fox - microorganisms;
- detrital : detritus - fly larvae - frog - snake - hawk - microorganisms.
Rice. 3. Example of a food chain.
The top of the food chain is always occupied by a predator, which is the last-order consumer in its range. The number of top predators is not regulated by other predators and depends only on external environmental factors. Examples are killer whales, monitor lizards, and large sharks.
What have we learned?
We found out what food chains there are in nature and how the links are located in them. All living organisms on Earth are interconnected by food chains through which energy is transferred. Autotrophs themselves produce nutrients and are food for heterotrophs, which, when dying, become a breeding ground for saprotrophs. Decomposers can also become food for consumers and produce a nutrient medium for producers without interrupting the food chain.
Test on the topic
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1. Producers(producers) produce organic substances from inorganic ones. These are plants, as well as photo- and chemosynthetic bacteria.
2. Consumers(consumers) consume finished organic substances.
- 1st order consumers feed on producers (cow, carp, bee)
- 2nd order consumers feed on first order consumers (wolf, pike, wasp)
etc.
3. Decomposers(destroyers) destroy (mineralize) organic substances to inorganic ones - bacteria and fungi.
Example of a food chain: cabbage → cabbage white caterpillar → tit → hawk. The arrow in the food chain is directed from the one who is eaten towards the one who eats. The first link of the food chain is the producer, the last is the higher-order consumer or decomposer.
The food chain cannot contain more than 5-6 links, because when moving to each next link, 90% of the energy is lost ( 10% rule, rule of the ecological pyramid). For example, a cow ate 100 kg of grass, but gained weight only by 10 kg, because...
a) she did not digest part of the grass and threw it away with feces
b) some of the digested grass was oxidized to carbon dioxide and water to produce energy.
Each subsequent link in the food chain weighs less than the previous one, so the food chain can be represented as biomass pyramids(at the bottom are producers, there are the most of them, at the very top are consumers of the highest order, there are the fewest of them). In addition to the biomass pyramid, you can build a pyramid of energy, numbers, etc.
Establish a correspondence between the function performed by an organism in a biogeocenosis and the representatives of the kingdom performing this function: 1) plants, 2) bacteria, 3) animals. Write the numbers 1, 2 and 3 in the correct order.
A) the main producers of glucose in the biogeocenosis
B) primary consumers of solar energy
C) mineralize organic matter
D) are consumers of different orders
D) ensure the absorption of nitrogen by plants
E) transfer substances and energy in food chains
Answer
Answer
Choose three options. Algae in a reservoir ecosystem constitute the initial link in most food chains, since they
1) accumulate solar energy
2) absorb organic substances
3) capable of chemosynthesis
4) synthesize organic substances from inorganic ones
5) provide energy and organic matter to animals
6) grow throughout life
Answer
Choose one, the most correct option. In the ecosystem of a coniferous forest, consumers of the 2nd order include
1) spruce
2) forest mice
3) taiga ticks
4) soil bacteria
Answer
Establish the correct sequence of links in the food chain using all the named objects
1) ciliate-slipper
2) Bacillus subtilis
3) seagull
4) fish
5) mollusk
6) silt
Answer
Establish the correct sequence of links in the food chain using all the named representatives
1) hedgehog
2) field slug
3) eagle
4) plant leaves
5) fox
Answer
Establish a correspondence between the characteristics of organisms and the functional group to which it belongs: 1) producers, 2) decomposers
A) absorb carbon dioxide from the environment
B) synthesize organic substances from inorganic ones
B) include plants, some bacteria
D) feed on ready-made organic substances
D) include saprotrophic bacteria and fungi
E) decompose organic substances into minerals
Answer
1. Choose three options. Producers include
1) mold fungus - mukor
2) reindeer
3) common juniper
4) wild strawberries
5) fieldfare
6) lily of the valley
Answer
2. Choose three correct answers out of six. Write down the numbers under which they are indicated. Producers include
1) pathogenic prokaryotes
2) brown algae
3) phytophages
4) cyanobacteria
5) green algae
6) symbiont mushrooms
Answer
3. Choose three correct answers out of six and write down the numbers under which they are indicated. Producers of biocenoses include
1) penicillium mushroom
2) lactic acid bacterium
3) silver birch
4) white planaria
5) camel thorn
6) sulfur bacteria
Answer
4. Choose three correct answers out of six and write down the numbers under which they are indicated. Producers include
1) freshwater hydra
2) cuckoo flax
3) cyanobacterium
4) champignon
5) ulotrix
6) planaria
Answer
FORMED 5. Choose three correct answers out of six and write down the numbers under which they are indicated. Producers include
A) yeast
Choose three correct answers out of six and write down the numbers under which they are indicated. In biogeocenosis, heterotrophs, unlike autotrophs,
1) are producers
2) provide a change in ecosystems
3) increase the supply of molecular oxygen in the atmosphere
4) extract organic substances from food
5) convert organic residues into mineral compounds
6) act as consumers or decomposers
Answer
1. Establish a correspondence between the characteristics of an organism and its membership in the functional group: 1) producer, 2) consumers. Write numbers 1 and 2 in the correct order.
A) synthesize organic substances from inorganic ones
B) use ready-made organic substances
B) use inorganic substances in the soil
D) herbivores and carnivores
D) accumulate solar energy
E) use animal and plant foods as a source of energy
Answer
2. Establish a correspondence between ecological groups in the ecosystem and their characteristics: 1) producers, 2) consumers. Write numbers 1 and 2 in the order corresponding to the letters.
A) are autotrophs
B) heterotrophic organisms
C) the main representatives are green plants
D) produce secondary products
D) synthesize organic compounds from inorganic substances
Answer
Answer
Establish the sequence of the main stages of the cycle of substances in the ecosystem, starting with photosynthesis. Write down the corresponding sequence of numbers.
1) destruction and mineralization of organic residues
2) primary synthesis of organic substances from inorganic substances by autotrophs
3) use of organic substances by consumers of the second order
4) use of the energy of chemical bonds by herbivorous animals
5) use of organic substances by consumers of the third order
Answer
Establish the sequence of arrangement of organisms in the food chain. Write down the corresponding sequence of numbers.
1) frog
2) already
3) butterfly
4) meadow plants
Answer
1. Establish a correspondence between organisms and their function in the forest ecosystem: 1) producers, 2) consumers, 3) decomposers. Write the numbers 1, 2 and 3 in the correct order.
A) horsetails and ferns
B) molds
C) tinder fungi that live on living trees
D) birds
D) birch and spruce
E) putrefaction bacteria
Answer
2. Establish a correspondence between organisms - inhabitants of the ecosystem and the functional group to which they belong: 1) producers, 2) consumers, 3) decomposers.
A) mosses, ferns
B) toothless and pearl barley
B) spruce, larches
D) molds
D) putrefactive bacteria
E) amoebas and ciliates
Answer
3. Establish a correspondence between organisms and functional groups in the ecosystems to which they belong: 1) producers, 2) consumers, 3) decomposers. Write numbers 1-3 in the order corresponding to the letters.
A) spirogyra
B) sulfur bacteria
B) mukor
D) freshwater hydra
D) kelp
E) putrefaction bacteria
Answer
4. Establish a correspondence between organisms and functional groups in the ecosystems to which they belong: 1) producers, 2) consumers. Write numbers 1 and 2 in the order corresponding to the letters.
A) naked slug
B) common mole
B) gray toad
D) black polecat
D) kale
E) common cress
Answer
5. Establish a correspondence between organisms and functional groups: 1) producers, 2) consumers. Write numbers 1 and 2 in the order corresponding to the letters.
A) sulfur bacteria
B) field mouse
B) meadow bluegrass
D) honey bee
D) creeping wheatgrass
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated in the table. Which of the following organisms are consumers of finished organic matter in the pine forest community?
1) soil green algae
2) common viper
3) sphagnum moss
4) pine undergrowth
5) black grouse
6) wood mouse
Answer
1. Establish a correspondence between an organism and its membership in a certain functional group: 1) producers, 2) decomposers. Write numbers 1 and 2 in the correct order.
A) red clover
B) chlamydomonas
B) putrefaction bacterium
D) birch
D) kelp
E) soil bacterium
Answer
2. Establish a correspondence between the organism and the trophic level at which it is located in the ecosystem: 1) Producer, 2) Reducer. Write numbers 1 and 2 in the correct order.
A) Sphagnum
B) Aspergillus
B) Laminaria
D) Pine
D) Penicill
E) Putrefactive bacteria
Answer
3. Establish a correspondence between organisms and their functional groups in the ecosystem: 1) producers, 2) decomposers. Write numbers 1 and 2 in the order corresponding to the letters.
A) sulfur bacteria
B) cyanobacterium
B) fermentation bacterium
D) soil bacterium
D) mukor
E) kelp
Answer
Choose three options. What is the role of bacteria and fungi in the ecosystem?
1) convert organic substances of organisms into minerals
2) ensure the closure of the circulation of substances and energy conversion
3) form primary production in the ecosystem
4) serve as the first link in the food chain
5) form inorganic substances available to plants
6) are consumers of the second order
Answer
1. Establish a correspondence between a group of plants or animals and its role in the pond ecosystem: 1) producers, 2) consumers. Write numbers 1 and 2 in the correct order.
A) coastal vegetation
B) fish
B) amphibian larvae
D) phytoplankton
D) bottom plants
E) shellfish
Answer
2. Establish a correspondence between the inhabitants of the terrestrial ecosystem and the functional group to which they belong: 1) consumers, 2) producers. Write numbers 1 and 2 in the order corresponding to the letters.
A) alder
B) typograph beetle
B) elm
D) sorrel
D) crossbill
E) forty
Answer
3. Establish a correspondence between the organism and the functional group of the biocenosis to which it belongs: 1) producers, 2) consumers. Write numbers 1 and 2 in the order corresponding to the letters.
A) tinder fungus
B) creeping wheatgrass
B) sulfur bacteria
D) Vibrio cholerae
D) ciliate-slipper
E) malarial plasmodium
Answer
4. Establish a correspondence between the examples and ecological groups in the food chain: 1) producers, 2) consumers. Write numbers 1 and 2 in the order corresponding to the letters.
A) hare
B) wheat
B) earthworm
D) tit
D) kelp
E) small pond snail
Answer
Establish a correspondence between animals and their roles in the biogeocenosis of the taiga: 1) consumer of the 1st order, 2) consumer of the 2nd order. Write numbers 1 and 2 in the correct order.
A) nutcracker
B) goshawk
B) common fox
D) red deer
D) brown hare
E) common wolf
Answer
Answer
Determine the correct sequence of organisms in the food chain.
1) wheat grains
2) red fox
3) bug harmful turtle
4) steppe eagle
5) common quail
Answer
Establish a correspondence between the characteristics of organisms and the functional group to which they belong: 1) Producers, 2) Decomposers. Write numbers 1 and 2 in the correct order.
A) Is the first link in the food chain
B) Synthesize organic substances from inorganic ones
B) Use the energy of sunlight
D) They feed on ready-made organic substances
D) Return minerals to ecosystems
E) Decompose organic substances into minerals
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. In the biological cycle occurs:
1) decomposition of producers by consumers
2) synthesis of organic substances from inorganic by producers
3) decomposition of consumers by decomposers
4) consumption of finished organic substances by producers
5) nutrition of producers by consumers
6) consumption of finished organic substances by consumers
Answer
1. Select organisms that are decomposers. Three correct answers out of six and write down the numbers under which they are indicated.
1) penicillium
2) ergot
3) putrefactive bacteria
4) mukor
5) nodule bacteria
6) sulfur bacteria
Answer
2. Choose three correct answers out of six and write down the numbers under which they are indicated. Decomposers in an ecosystem include
1) rotting bacteria
2) mushrooms
3) nodule bacteria
4) freshwater crustaceans
5) saprophytic bacteria
6) chafers
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. Which of the following organisms are involved in the decomposition of organic residues to mineral ones?
1) saprotrophic bacteria
2) mole
3) penicillium
4) chlamydomonas
5) white hare
6) mukor
Answer
Establish the order of organisms in the food chain, starting with the organism that absorbs sunlight. Write down the corresponding sequence of numbers.
1) gypsy moth caterpillar
2) linden
3) common starling
4) sparrowhawk
5) fragrant beetle
Answer
Choose one, the most correct option. What do fungi and bacteria have in common?
1) the presence of cytoplasm with organelles and a nucleus with chromosomes
2) asexual reproduction using spores
3) their destruction of organic substances to inorganic ones
4) existence in the form of unicellular and multicellular organisms
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. In a mixed forest ecosystem, the first trophic level is occupied by
1) granivorous mammals
2) warty birch
3) black grouse
4) gray alder
5) angustifolia fireweed
6) dragonfly rocker
Answer
1. Choose three correct answers out of six and write down the numbers under which they are indicated. The second trophic level in a mixed forest ecosystem is occupied by
1) moose and roe deer
2) hares and mice
3) bullfinches and crossbills
4) nuthatches and tits
5) foxes and wolves
6) hedgehogs and moles
Answer
2. Choose three correct answers out of six and write down the numbers under which they are indicated. The second trophic level of the ecosystem includes
1) Russian muskrat
2) black grouse
3) cuckoo flax
4) reindeer
5) European marten
6) field mouse
Answer
Establish the sequence of organisms in the food chain. Write down the corresponding sequence of numbers.
1) fish fry
2) algae
3) perch
4) daphnia
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. In food chains, first-order consumers are
1) echidna
2) locusts
3) dragonfly
4) fox
5) moose
6) sloth
Answer
Place the organisms in the detrital food chain in the correct order. Write down the corresponding sequence of numbers.
1) mouse
2) honey fungus
3) hawk
4) rotten stump
5) snake
Answer
Establish a correspondence between the animal and its role in the savanna: 1) consumer of the first order, 2) consumer of the second order. Write numbers 1 and 2 in the order corresponding to the letters.
A) antelope
B) lion
B) cheetah
D) rhinoceros
D) ostrich
E) neck
Answer
Analyze the table “Trophic levels in the food chain.” For each lettered cell, select the appropriate term from the list provided. Write down the selected numbers in the order corresponding to the letters.
1) secondary predators
2) first level
3) saprotrophic bacteria
4) decomposers
5) second-order consumers
6) second level
7) producers
8) tertiary predators
Answer
Place the organisms in the correct order in the decomposition chain (detritus). Write down the corresponding sequence of numbers.
1) small carnivorous predators
2) animal remains
3) insectivores
4) saprophagous beetles
Answer
Analyze the table “Trophic levels in the food chain.” Fill in the blank cells of the table using the terms in the list. For each lettered cell, select the appropriate term from the list provided. Write down the selected numbers in the order corresponding to the letters.
List of terms:
1) primary predators
2) first level
3) saprotrophic bacteria
4) decomposers
5) consumers of the first order
6) heterotrophs
7) third level
8) secondary predators
Answer
Analyze the table “Functional groups of organisms in an ecosystem.” For each lettered cell, select the appropriate term from the list provided. Write down the selected numbers in the order corresponding to the letters.
1) viruses
2) eukaryotes
3) saprotrophic bacteria
4) producers
5) algae
6) heterotrophs
7) bacteria
8) mixotrophs
Answer
Look at the picture of a food chain and indicate (A) the type of food chain, (B) the producer, and (C) the second-order consumer. For each lettered cell, select the appropriate term from the list provided. Write down the selected numbers in the order corresponding to the letters.
1) detrital
2) Canadian pondweed
3) osprey
4) pasture
5) big pond snail
6) green frog
Answer
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. Decomposers in the forest ecosystem participate in the cycle of substances and energy transformations, since
1) synthesize organic substances from minerals
2) release energy contained in organic residues
3) accumulate solar energy
4) decompose organic matter
5) promote the formation of humus
6) enter into symbiosis with consumers
Answer
Establish the order in which the listed objects should be located in the food chain.
1) cross spider
2) weasel
3) dung fly larva
4) frog
5) manure
Answer
Choose two correct answers out of five and write down the numbers under which they are indicated. Environmental terms include
1) heterosis
2) population
3) outbreeding
4) consumer
5) divergence
Answer
Choose three correct answers out of six and write down the numbers under which they are indicated. Which of the following animals can be classified as consumers of the second order?
1) gray rat
2) Colorado potato beetle
3) dysenteric amoeba
4) grape snail
5) ladybug
6) honey bee
Answer
© D.V. Pozdnyakov, 2009-2019
Complex nutritional interactions exist between autotrophs and heterotrophs in ecosystems. Some organisms eat others, and thus carry out the transfer of substances and energy - the basis for the functioning of the ecosystem.
Within an ecosystem, organic matter is created by autotrophic organisms such as plants. Plants are eaten by animals, which in turn are eaten by other animals. This sequence is called a food chain (Fig. 1), and each link in the food chain is called a trophic level.
Distinguish
Grassland food chains(grazing chains) - food chains that begin with autotrophic photosynthetic or chemosynthetic organisms (Fig. 2.). Pasture food chains are found predominantly in terrestrial and marine ecosystems.
An example is the grassland food chain. This chain begins with the capture of solar energy by the plant. The butterfly, feeding on the nectar of a flower, represents the second link in this chain. A dragonfly, a predatory flying insect, attacks a butterfly. A frog hiding among the green grass catches a dragonfly, but itself serves as prey for such a predator as the grass snake. He could have spent the whole day digesting the frog, but before the sun had even set, he himself became the prey of another predator.
The food chain, going from a plant through a butterfly, dragonfly, frog, snake to a hawk, indicates the direction of movement of organic substances, as well as the energy contained in them.
In oceans and seas, autotrophic organisms (unicellular algae) exist only up to the depth of light penetration (maximum up to 150-200 m). Heterotrophic organisms living in deeper layers of water rise to the surface at night to feed on algae, and in the morning they go deeper again, making daily vertical migrations up to 500-1000 m long. In turn, with the onset of morning, heterotrophic organisms from even deeper layers rise to the top to feed on other organisms descending from the surface layers.
Thus, in the deep seas and oceans there is a kind of “food ladder”, thanks to which organic matter created by autotrophic organisms in the surface layers of water is transported along the chain of living organisms to the very bottom. In this regard, some marine ecologists consider the entire water column to be a single biogeocenosis. Others believe that environmental conditions in the surface and bottom layers of water are so different that they cannot be considered as a single biogeocenosis.
Detrital food chains(decomposition chains) - food chains that begin with detritus - dead remains of plants, corpses and animal excrement (Fig. 2).
Detrital chains are most typical for communities of continental reservoirs, the bottom of deep lakes, oceans, where many organisms feed on detritus formed by dead organisms of the upper illuminated layers of the reservoir or that entered the reservoir from terrestrial ecosystems, for example, in the form of leaf litter.
The ecosystems of the bottom of the seas and oceans, where sunlight does not penetrate, exist only due to the constant settling there of dead organisms living in the surface layers of water. The total mass of this substance in the World Ocean per year reaches at least several hundred million tons.
Detrital chains are also common in forests, where most of the annual increase in the live weight of plants is not consumed directly by herbivores, but dies, forming litter, and is then decomposed by saprotrophic organisms, followed by mineralization by decomposers. Fungi are of great importance in the decomposition of dead plant matter, especially wood.
Heterotrophic organisms that feed directly on detritus are called detritivores. In terrestrial ecosystems they are many species of insects, worms, etc. Large detritivores, which include some species of birds (vultures, crows, etc.) and mammals (hyenas, etc.) are called scavengers.
In aquatic ecosystems, the most common detritivores are arthropods - aquatic insects and their larvae, and crustaceans. Detritivores can feed on other, larger heterotrophic organisms, which themselves can serve as food for predators.
Trophic levels
Typically, different trophic levels in ecosystems are not separated in space. However, in some cases they are quite clearly differentiated. For example, in geothermal sources, autotrophic organisms - blue-green algae and autotrophic bacteria, forming specific algal-bacterial communities ("mats") are common at temperatures above 40-45 ° C. At lower temperatures they do not survive.
On the other hand, heterotrophic organisms (mollusks, larvae of aquatic insects, etc.) are not found in geothermal springs at temperatures above 33-36 ° C, so they feed on fragments of mats carried by the current to areas with lower temperatures.
Thus, in such geothermal sources, an autotrophic zone is clearly distinguished, where only autotrophic organisms are common, and a heterotrophic zone, where autotrophic organisms are absent and only heterotrophic organisms are found.
Trophic networks
In ecological systems, although there are a number of parallel food chains, e.g.
herbaceous vegetation -> rodents -> small predators
herbaceous vegetation -> ungulates -> large predators,
which unite the inhabitants of the soil, herbaceous cover, tree layer, there are other relationships. In most cases, the same organism can serve as a source of food for many organisms and thus be integral part different food chains and prey to different predators. For example, daphnia can be eaten not only by small fish, but also by the predatory crustacean Cyclops, and roach can be eaten not only by pike, but also by otter.
The trophic structure of a community reflects the relationship between producers, consumers (separately of the first, second, etc. orders) and decomposers, expressed either by the number of individuals of living organisms, or their biomass, or the energy contained in them, calculated per unit area per unit time.
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