And this is one of our most aggressive predators fresh water! Consider this fact: it pursues its prey so stubbornly that it loses control of itself, jumps out into very small places, even onto the shore, where it dies. Or another fact: in the second month of life, he already swallows the young of other fish. Many people believe that pike perch and pike are sworn enemies: they always fight. The war is that they strive to get each other out of a good hole...

Traveling along the Volga delta in a kulas - a single-seater boat, I turned into an erik, which struck me with its gloom and mystery. For this, apparently, he was called Leshachy. It is very small - only a hundred meters long, flows out of the Chilimny erik - quite wide, covered with patterned leaves of chilim - water chestnut, and flows into... It’s hard to say about this: it actually has no mouth. The banks are densely overgrown with young willows and old, blackened willow grass. At the end of Leshachy they connected with crowns bent over the water and formed a green tunnel, and then a dead end. Therefore, it was cool and dark here even at noon. Dried algae hung from the lower branches of trees and bushes, looking like large black-green clumps that had fallen here during high water. Even further away lay two half-sunken, spreading sedges, brought by the spring flood. The bark had long fallen off from them, and the water polished them, and they began to look like the yellowed bones of some long-extinct animals. Erik penetrates the thicket of willows and willows, the pile of dead sedge trees and immediately gives his water to the Big Kultuk.

I grabbed a branch touching the side of the kulas and stopped it. At that same moment it seemed that the goblin’s head would poke out through the living and dead trees and dried algae and ask in a sepulchral voice:

Why did you come to my kingdom? But seconds and minutes passed, the goblin did not appear. Having driven 30 m away from the dead end, I threw a spoon. It sank for a long time, and along the fishing line you could feel the spinner falling from branch to branch of the underwater parts of trees and bushes. Expecting that it was about to get hooked, I felt a tug, hooked it and began to reel in the line. Soon a bright green pike perch surfaced near the side and immediately fell into the landing net. He weighed 1.5 kg. The second cast brought another similar pike perch. To catch the third one, I had to make five casts. After that, no one was interested in my spinner anymore. Apparently, if there were pike perch left in Leshachy, I scared them away.

The next day I looked here again. After the first cast I caught a 3-kilogram pike, the next one after the tenth cast. There were no more bites. I released the pike back into the erik - I didn’t need fish then. On the third day, as expected, pike perch were biting in this erik, on the fourth - pike, on the fifth - pike perch again. How can we explain this “schedule”?

I happened to be there - in the vastness of the Volga delta - in one of the pits I alternately caught perches and small catfish: it seemed that they were not so much at odds with each other. On Zolotitsa, which flows into the White Sea, with a spinning rod, when casting far away, I caught anadromous trout, and when casting close-in, in small and quiet backwaters, I caught pike. But I don’t remember a case where pike perch and pike perch lived in the same hole or on the same stretch. They are always fighting. Today, for example, the pike “won” - which means there will be more of them in the pit or on the reach than pike perch. The next day there were more pike perch, they fought the pikes and drove them away.

These are by no means bloodless fights: first one side, then the other was bitten. Of course, the outcome of the fights is affected not only by the number and weight of individuals, but also by the size of the hole or reach and the amount of food in them.

Lesson topic: Relationships between organisms.

Target: consolidation and deepening of students’ knowledge about the variety of types of interaction between living organisms and their significance in the life of species.

Tasks:

Continue the development of cognitive, communicative and health-preserving competencies in students through:

system of common environmental concepts about the adaptability of organisms to living together in communities;

illustration of the diversity of biotic relationships between organisms,

the ability to identify types of relationships between organisms and give a brief description of them.

fostering environmental literacy and respect for nature;

Lesson type: combined.

Teaching methods:

verbal ( heuristic conversation with elements independent work);

partial-search (execution independent tasks);

visual (filling out tables and working with illustrations).

Form of work: individual, group.

Equipment: projector, screen, computer, presentation, handouts (tests, table “Biotic interactions”, cards with tasks for working in groups).

Lesson plan:

I. Organizational moment.

IV. Homework.

V. Lesson summary.

During the classes.

I. Organizational moment.

Greetings, journal entry.

II. Learning new material.

The topic of our lesson today: “Relationships between organisms” (slide 1). This topic has already been discussed by you several times, starting with the lessons of the surrounding world and natural history and ending with the lessons general biology in 9th grade, therefore, the main goal of the lesson is to consolidate and deepen knowledge about the variety of types of interaction between living organisms and their significance in the life of species. (slide 2)

Before we start talking about this, let's remember the material from previous lessons, for which I suggest you complete small test: (slide 3)

Test "environmental factors"

1. Which of the following factors can be classified as abiotic:

A - Spring river floods.
B - Deforestation.

B - Application of fertilizers to the soil,

2. A nature reserve was created in the forest area. To which environmental factor can this fact be attributed?

A - Biotic.
B - Abiotic.

B - Anthropogenic.

3. The biotic factor is understood as:

A - Sum of exposure to living organisms.
B - Human impact on organisms.

B - Factors of inanimate nature.

4. From the listed examples, select the anthropogenic factor:

A - Light.

B - Relationships between individuals in a population.

B - Industrial development.

5. Dead tree leaves form litter, which serves as a place
habitat and food for many organisms. What factors does this relate to?
phenomenon?

A - Anthropogenic.

B - Biotic.

B - Abiotic.

D - Complex action of factors.

Exchange papers with completed tests with your desk neighbor and check each other’s answers for correctness (no mistakes – “5”;

One error – “4”;

Two errors – “3”;

Three or more errors – “2”).

Raise your hands those who completed the test without errors... with one error... with two errors... with three or more... (we conclude that the material has been mastered)

Let's move on to learning new material.

The life of any living organism is impossible without other organisms. (slide 4). Its well-being depends on the many species that affect it. The entire world of animals, fungi and a significant part of bacteria lives due to those compounds that are created by plants. But plants could not exist without microorganisms, animals - pollinators and seed distributors, fungi that help feed the roots and other plants that create the necessary microclimate.

The connections between different organisms are called biotic. All nature is permeated with these connections. They are varied and can be straight(carried out by the direct influence of one species on another, for example, a predator on prey), or indirect(through influence on external environment or other types). (Students make notes in their notebooks as the teacher explains). Today we will look at the main types of interaction between organisms.

There are several basic types of interactions between organisms. Like most biological categories, they are not concepts with absolutely clear boundaries, therefore there is no generally accepted single classification of them. As an example, consider the classification “+,0,-.” This classification is based on the principle of the influence that some organisms have on others in the process of mutual contacts. These relationships can be indicated by mathematical symbols “+”, “–”, “0” (positive, negative, neutral).

There are tables in front of you (Appendix 1) that need to be filled out during the lesson.

Make up all possible combinations that can be used in this classification and fill out the first column of the table (slide 5).

As you can see, relationships can develop in communities of terrestrial and aquatic organisms, various types(slide 6). Let's look at them in more detail.

We look at the slides and answer the questions:

What is the nature of the relationships between the organisms depicted on the slide? Give reasons for your answer.

What is this type of relationship called? Define it.

Many of the types are already known to students from previous biology courses, so the students name them on their own and give definitions. If difficulties arise or an unknown concept is encountered, the teacher defines and characterizes this type of relationship.

As we work, we fill out the table and write down the definitions in our notebooks.

In nature, there are often mutually beneficial relationships between species of organisms, in which they receive mutual benefits - these are diverse symbiotic relationship.
A prerequisite for a symbiotic relationship is living together, a certain degree of cohabitation of organisms.

Mutualism(obligate symbiosis). (slide 7)

A classic example of symbiosis are lichens, which are a close, mutually beneficial cohabitation of fungi and algae. Another example of symbiosis is the relationship between termites and their intestinal cohabitants - flagellates. These protozoa produce an enzyme that breaks down fiber into sugars. Termites do not have their own enzymes to digest cellulose and would die without their symbionts. And flagellates, in turn, find favorable conditions in the intestine that promote their survival. They are not found in a free state in nature.

Protocooperation(facultative symbiosis). (slide 8)

A well-known example of symbiosis is the cohabitation of green plants (primarily trees) and mushrooms.
One type of mutually beneficial relationship is proto-cooperation (literally: primary cooperation). In this case, coexistence is beneficial for both species, but not necessary for them, that is, it is not an indispensable condition for their survival. An example is the distribution of seeds of some forest plants by ants, and the pollination of various meadow plants by bees.

Commensalism– A form of relationship in which one species receives some advantage without causing harm or benefit to the other. The basis for this type of relationship can be shared space, substrate, shelter, movement, or most often food. Using the characteristics of the host’s lifestyle or structure, commensalism derives one-sided benefit from this. Its presence usually remains indifferent to the owner (for example, the dwelling of the Mediterranean carp fish in the body cavity of some species of sea cucumbers, which it uses as a shelter), large mammals (dogs, deer) serve as carriers of fruits and seeds with hooks (like burdock), without receiving This is neither a detriment nor an advantage.

Tenancy() - one organism uses another (or its home) as a place of residence without causing harm to the latter. (slide 9)

Freeloading- one organism feeds on the leftover food of another. (slide 10)

Companionship- both species consume different substances or parts of the same food. (slide 11)

Predation – this type of relationship between organisms in which representatives of one species kill and eat representatives of another. (slide 12) A typical predator (wolf, lynx, mink) is characterized by hunting behavior. But in addition to predators - hunters, there is a large group of predators - gatherers, whose feeding method consists of simply searching and collecting prey. These are, for example, many insectivorous birds that collect food on the ground, in the grass or in trees. Predation is a widespread form of biotic relationships.

The significance of predation can only be understood by considering the phenomenon at the population level. The long-term connection between the populations of predator and prey gives rise to their interdependence, which acts like a regulator, preventing too sharp fluctuations in numbers or preventing the accumulation of weakened or sick individuals in populations. In some cases, predation can significantly weaken the negative consequences of interspecific competition and increase the stability and diversity of species in communities.

Under a microscope he discovered that on the flea

A flea that bites lives;

On that flea there is a tiny flea,

A tooth pierces a flea angrily

Flea, and so adinfinitum.

Herbivory.(slide 14). Predation is often called any consumption of one organism by another. Consequently, herbivory can also be considered one of the forms of predation.

Neutralism - both populations have no effect on each other.(slide 15). Neutrality is the cohabitation of two species on the same territory, which has neither positive nor negative consequences for them. For example, squirrels and moose do not have significant effects on each other.

Antibiosis.

Amensalism(slide 16) - a relationship in which one organism influences another and suppresses its vital activity, while it itself does not experience any negative influences on the part of the suppressed. For example, the impossibility of survival of a small light-loving herbaceous plant under the dense shade of beech or spruce. In amensalism, one species suffers while the other develops normally: for example, mold Penicillium secretes penicillin, a substance that inhibits the growth of various bacteria, but the bacteria have no effect on the mold. In clinical trials of penicillin, it was found that its use increased the number of fungal diseases, since in natural conditions the development of fungi is inhibited by the presence of bacteria.

Allelopathy (slide 17) - a form of antibiosis in which organisms have a mutually harmful effect on each other, due to their vital factors (for example, secretions of substances). Found mainly in plants, mosses, and fungi. Moreover, the harmful influence of one organism on another is not necessary for its life and does not bring it any benefit.

Competition(slide 18) - a form of antibiosis in which two types of organisms are biological enemies in their essence (usually due to a common food supply or disabilities for reproduction). For example, between predators of the same species and the same population or different types eating the same food and living in the same territory. Thus, interspecific and intraspecific competition can be distinguished. In this case, harm caused to one organism benefits another, and vice versa.

So, we have considered all possible types of relationships between organisms in nature. Each biocenosis is simultaneously characterized by many different relationships, which is shown in the following diagram (slide 19).

Think and say: what results do all the variety of types of relationships between organisms that we have studied lead to? Students offer their options, highlight the main points, and make notes in their notebooks. (slide 20)

III. Consolidation of the studied material.

Group work

Task 1. Solving practical problems.

Task 1. With the mass shooting of birds of prey (eagle owls, hawks), the number of partridges and black grouse decreases; When wolves are destroyed, the number of deer decreases. How can this be explained?

Answer: the predator has a regulatory effect on the prey population, destroying sick and weakened individuals. When the predator population decreases, the prey population decreases.

Problem 2. There were many ferns growing in the forest, but after it was cut down, these plants disappeared. Why?

Answer: Ferns grow in moist, shady areas under the forest canopy. Deforestation deprived them of favorable conditions.

Problem 3. Both sparrows and jackdaws feast on cherry fruits. But jackdaws swallow the cherry fruit whole, and sparrows only peck at the juicy pulp of the fruit. Which of these birds is healthier for cherries?

Answer: as a result of the raid of sparrows, the cherry fruits will only be spoiled; the seeds in the pits will remain on the parent plant. Jackdaw is healthier for cherries: the bird will swallow the fruit whole, the seed inside the pit will not be damaged, then the pit will be exposed to intestinal juices - this will improve the germination of the seed, and then along with the droppings it will be thrown away far from the parent plant, which contributes to the spread of the species.

Task 4. All the old hollow trees in the forest were cut down. Large young trees were eaten by pests. The forest died. What is the connection between these phenomena?

Answer: insectivorous birds lived in hollow trees - hollow nesters and bats. They were deprived of housing and left the forest. Then the insect pests multiplied in such numbers that they destroyed the remaining trees.

Task 2. Read the list of living organisms and write down the pairs that are connected:

symbiotic (group 3)______________________________

competitive (group 2)________________________________

predatory (group 1)_________________________________

Commensalitic (group 4)___________________________

Linden, oak, clover, dragonfly, bee, porcini mushroom, ladybug, mosquito, frog, hedgehog, Scots pine, common viper, May beetle larva, roundworm, bark beetle, human, squirrel, crow, woodpecker.

Conclusion.

All groups coped well with the proposed tasks (or not so well, as assessed by the teacher together with the students). I believe that everyone will agree with my following words:

The relationships between organisms in nature are complex and diverse, and often the line between them is arbitrary. As a result of the complexity and interweaving of connections between species, careless human intervention in the life of nature can cause a chain reaction of events that will lead to unexpected and undesirable consequences. Understanding this, a person is obliged to treat nature carefully, with care, in order to preserve it.

IV. Homework.

§17.4

V. Lesson summary.

We recognize the most active students and assign grades for their work in class.

Annex 1

Biotic interactions

Characteristics of relationships

Relationship type

Examples of relationships of this type

+ ; +

Symbiosis

Mutualism (obligate)

Protocooperation (optional)

Fungus and algae (lichens)

Termites and flagellates

Aphids and ants

Mycorrhiza on tree roots

+ ; 0

Commensalism

Tenancy

Freeloading

Companionship

Epiphytic plants on tree trunks

Lions and hyenas

Shark and fish stuck

Butterfly and caterpillar on one plant

+ ; -

Predation

Actually predation

Herbivory (phytophagy)

Wolves and moose

Ladybug and aphid

Scabies mite and man

Hare and grass

0 ; 0

Neutralism

Squirrels and moose in the same forest

Mosquito and birch

0 ; -

Amensalism

Beech and bluebell

Spruce and pine

- ; -

Antibiosis

Allelopathy

Interspecific competition

Intraspecific competition

Release of phytoncides by some shrubs

Fox and wolf

Fight for territory, the possibility of reproduction, etc.

Tasks and exercises for school course general ecology 1

Continuation. See No. 15/2002

(Printed with abbreviations)

Ways of influence of organisms on the environment

1. It has rained. A bright hot sun came out from behind a cloud. In which area will the soil moisture content be greater after five hours (soil type is the same): a) on a freshly plowed field; b) in a ripe wheat field; c) in an ungrazed meadow; d) in a grazing meadow? Explain why.
(Answer: V. The thicker the vegetation cover, the less the soil heats up and, therefore, the less water will evaporate.)

2. Explain why ravines form more often in non-forested areas natural areas: steppes, semi-deserts, deserts. What human activities lead to the formation of ravines?
(Answer: The root systems of trees and shrubs, to a greater extent than of herbaceous vegetation, retain soil when it is washed away by water flows, therefore, in places where forest and shrub vegetation grow, ravines form less frequently than in fields, steppes and deserts. In the complete absence of vegetation (including grass), any flow of water will cause soil erosion. When vegetation is destroyed by humans (plowing, grazing, construction, etc.), increased soil erosion will always be observed.)

3.* It has been established that in summer, after the heat, more precipitation falls over the forest than over the nearby vast field.
(Answer: Why? Explain the role of the nature of vegetation in shaping the level of aridity in certain areas.
above open spaces the air heats up faster and stronger than above a forest. Rising upward, hot air turns raindrops into steam. As a result, when it rains, less water flows over a vast field than over a forest., soil salinization. Hot air rises. If the desert area is large enough, then this can significantly change the direction of air flows. As a result, less precipitation falls on bare areas, which leads to even greater desertification of the territory.)

4.* In some countries and islands the import of live goats is prohibited by law. The authorities motivate this by the fact that goats can harm the country’s nature and change the climate. Explain how this could be.
(Answer: goats eat not only grass, but also leaves and tree bark. Goats are capable of reproducing quickly. Having reached high numbers, they mercilessly destroy trees and shrubs. In countries with insufficient rainfall, this causes further drying of the climate. As a result, nature is impoverished, which negatively affects the country’s economy.)

Adaptive forms of organisms

1.* Why do wingless forms predominate among insects on small oceanic islands, while winged ones predominate on the nearby mainland or large islands?
(Answer: small oceanic islands are blown by strong winds. As a result, all small flying animals that are unable to withstand strong winds are blown into the ocean and die. In the course of evolution, insects living on small islands have lost the ability to fly.)

Adaptive rhythms of life

1. List the abiotic environmental factors known to you, the values of which change periodically and regularly over time.
(Answer: illumination during the day, illumination in throughout the year, temperature during the day, temperature throughout the year, humidity throughout the year and others.)

2. Select from the list those habitats in which animals do not have circadian rhythms (provided that they live only within one specific environment): lake, river, cave waters, soil surface, ocean floor at a depth of 6000 m, mountains, human intestines , forest, air, soil at a depth of 1.5 m, river bottom at a depth of 10 m, bark of a living tree, soil at a depth of 10 cm.
(Answer: waters of caves, ocean bottom, soil at a depth of 1.5 m.)

3. In what month do chinstrap Adélie penguins usually give birth in European zoos - May, June, October or February? Explain your answer.
(Answer: in October - in the Southern Hemisphere at this time it is spring.)

4. Why did the experiment with the acclimatization of the South American llama in the Tien Shan mountains (where the climate is similar to the usual conditions of the animal’s native places) end in failure?
(Answer: discrepancy between annual cycles - young animals were born in a new habitat in the fall (in the homeland of animals at this time it is spring) and died in the cold winter from lack of food.)

CHAPTER 2. COMMUNITIES AND POPULATIONS

Types of interactions between organisms

2. From the proposed list, make pairs of organisms that in nature can be in mutualistic (mutually beneficial) relationships with each other (the names of organisms can be used only once): bee, boletus mushroom, sea anemone, oak, birch, hermit crab, aspen, jay, clover , boletus mushroom, linden, nodule nitrogen-fixing bacteria.
(Answer: bee - linden; boletus mushroom - birch; sea anemone - hermit crab; oak - jay;

3. boletus mushroom – aspen; clover is a nodule nitrogen-fixing bacteria.)
(Answer: From the proposed list, make pairs of organisms between which trophic (food) connections can form in nature (the names of organisms can be used only once): heron, willow, aphid, amoeba, brown hare, ant, aquatic bacteria, wild boar, frog, currant , sundew, antlion, mosquito, tiger.

4. heron - frog; hare - willow; aphid - currant; amoeba – aquatic bacteria; antlion - ant; tiger - boar; sundew - mosquito.)

(Answer: Lichens are an example of biotic relationships:

5. A.)

Pairs of organisms cannot serve as an example of a “predator-prey” relationship (choose the correct answer):
a) pike and crucian carp;
b) lion and zebra;
c) freshwater amoeba and bacteria;
d) antlion and ant;

(Answer: d) jackal and vulture.

d.)
A. The interaction of two or more individuals, the consequences of which are negative for some and indifferent for others.
B. Interaction of two or more individuals, in which some use the leftover food of others without harming them.
B. Mutually beneficial interaction between two or more individuals.
D. Interaction of two or more individuals, in which some provide shelter to others, and this does not bring harm or benefit to the owner.
D. Cohabitation of two individuals that do not directly interact with each other.
E. The interaction of two or more individuals that have similar needs for the same limited resources, which leads to a decrease in the vital signs of the interacting individuals.
G. The interaction of two or more organisms, in which some feed on the living tissues or cells of others and receive from them a place of permanent or temporary habitat.

(Answer: 1 – B; 2 – D; 3 – E; 4 – A; 5 – G; 6 – B; 7 – F; 8 – Z.)

7. Why do you think advanced technologies for planting trees in poor soil involve contaminating the soil with certain types of fungi?
(Answer: A symbiotic relationship is formed between these fungi and the tree. Mushrooms quickly form a very branched mycelium and entwine tree roots with their hyphae. Thanks to this, the plant receives water and mineral salts from a huge area of soil surface. To achieve such an effect without mycelium, the tree would have to spend a lot of time, matter and energy on the formation of such an extensive root system. When planting in a new place, symbiosis with the fungus significantly increases the chances of the tree to take root safely.)

8.* Name the organisms that are human symbionts. What role do they play?
(Answer: representatives of bacteria and protozoa living in the human intestine. There are 250 billion microorganisms in 1 g of colon contents. Many substances that enter the human body with food are digested with their active participation. Without intestinal symbionts, normal development is impossible. A disease in which the number of symbiotic intestinal organisms decreases is called dysbiosis. Microorganisms also live in tissues, cavities and on the surface of human skin.)

9.* The relationship between an adult spruce and a neighboring oak seedling is an example:

(Answer: A.)

Laws and consequences of food relations

1. Match the proposed concepts and definitions:

A. An organism that actively seeks out and kills relatively large prey that are capable of fleeing, hiding, or resisting.
B. An organism (usually small in size) that uses living tissues or cells of another organism as a source of nutrition and habitat.
B. An organism that absorbs numerous food objects, usually of plant origin, for which it does not spend much effort searching.
D. An aquatic animal that filters water through itself with numerous small organisms that serve as food for it.
B. An organism that searches for and eats relatively small food objects that are not capable of running away or resisting.

(Answer: 1 – B; 2 – G; 3 – A; 4 – D; 5 – V.)

2. Explain why in China in the mid-twentieth century. Following the destruction of sparrows, the grain harvest sharply decreased. After all, sparrows are granivorous birds.
(Answer: adult sparrows feed mainly on seeds, but chicks need protein food for their development. While feeding their offspring, sparrows collect a huge number of insects, including pests of grain crops. The destruction of sparrows caused outbreaks of pests, which led to a reduction in harvests.)

Laws of competitive relations in nature

1. For each proposed pair of organisms, select a resource (from those given below) for which they can compete: lily of the valley - pine, field mouse - vole, wolf - fox, perch - pike, buzzard - tawny owl, badger - fox, rye – blue cornflower, saxaul – camel thorn, bumblebee – bee.
Resources: hole, nectar, wheat seeds, water, hares, light, small roaches, potassium ions, small rodents.
(Answer: lily of the valley and pine – potassium ions; field mouse and common vole – wheat seeds;

2.* wolf and fox are hares; perch and pike – small roach; the buzzard and the tawny owl are small rodents; badger and fox - hole; rye and cornflower - light; saxaul and camel thorn - water; bumblebee and bee - nectar.)
(Answer: Closely related species often live together, although it is generally accepted that the most intense competition exists between them. Why in these cases does not one species replace the other? 1 – very often closely related species living together occupy different ecological niches (they differ in the composition of their preferred food, in the method of obtaining food, use different microhabitats, are active in

3.* different time
(Answer: days); 2 – competition may be absent if the resource for which the species compete is in abundance; 3 – displacement does not occur if the number of a competitively stronger species is constantly limited by a predator or a third competitor; 4 - in an unstable environment in which conditions are constantly changing, they can alternately become favorable for one species or another.)

In nature, Scots pine forms forests on relatively poor soils in swampy or, conversely, dry places.

1. Select a value that estimates the population density indicator:

a) 20 individuals;
b) 20 individuals per hectare;
c) 20 individuals per 100 breeding females;
d) 20%;
e) 20 individuals per 100 traps;
e) 20 individuals per year.

(Answer: b.)

2. Select a value that estimates the birth rate (or death rate) of the population:

a) 100 individuals;
b) 100 individuals per year;
c) 100 individuals per hectare;
d) 100.

(Answer: b.)

3. White hares and brown hares living in the same territory are:

a) one population of one species;
b) two populations of two species;
c) two populations of the same species;
d) one population of different species.

(Answer: b.)

4. Forest felling was carried out annually on an area of 100 km2. At the time of the organization of this reserve, 50 moose were recorded. After 5 years, the number of moose increased to 650 animals. After another 10 years, the number of moose decreased to 90 and stabilized in subsequent years at the level of 80–110 animals.
Determine the population density of moose: a) at the time of the creation of the reserve; b) 5 years after the creation of the reserve; c) 15 years after the creation of the reserve. Explain why the number of moose initially increased sharply, and later fell and stabilized.
(Answer: a – 0.5 individuals/km2; b – 6.5 individuals/km2; c – 0.9 individuals/km2. The number of moose has increased due to protection in the reserve. Later, the number decreased, since logging is prohibited in reserves. This led to the fact that after 15 years, small trees growing in old clearings grew, and the food supply for moose decreased.)

5. Game experts established that in the spring, 8 sables lived on an area of 20 km2 of taiga forest, of which 4 were females (adult sables do not form permanent pairs). Every year, one female gives birth to an average of three cubs. The average mortality rate of sables (adults and calves) at the end of the year is 10%. Determine the number of sables at the end of the year; density in spring and at the end of the year;
(Answer: annual mortality rate; birth rate per year.

6.* Is the population: a) a group of cheetahs in the Moscow Zoo; b) family of wolves;
(Answer: c) perches in the lake; d) wheat on the field; e) snails of one species in one mountain gorge; f) bird market; g) brown bears on Sakhalin Island; h) a herd (family) of deer; i) red deer in Crimea;

7.* j) colony of rooks; k) all the plants of the spruce forest? Justify your answer.
(Answer: yes - c, d, g, i. A population is a group of individuals of the same species, interconnected, living in the same territory for a long time (several generations). A population is a natural grouping that has a certain gender, age, and spatial structure.) How can we explain the fact that if in a fight between two (non-fighting) dogs one exposes its unprotected neck, the other will not grab it, while in a fight between a lynx and a dog such behavior will be fatal for the dog that has exposed its neck? aggression between individuals of the same species is usually aimed at maintaining hierarchical and

8.* spatial structure
(Answer: population, and not to destroy fellow tribesmen.
A population, like a species, is a single whole, and the well-being of one individual largely determines the well-being of the population or species. The lynx will simply eat the dog.)
In the forest, scientists evenly placed traps for white hares. A total of 50 animals were caught. They were tagged and released.
A week later the capture was repeated. We caught 70 hares, 20 of which were already marked. Determine the number of hares in the study area, assuming that the animals tagged for the first time are evenly distributed throughout the forest.
50 marked individuals were to be distributed among the total number of hares (X) living in the study area. Their share in the repeated sample should reflect their share in the total number, i.e. 50 is to X as 20 is to 70. Solving the proportion: 50: X = 20: 70; X = 70x 50: 20 = 175.

Thus, the estimated number of hares in the study area is 175 individuals.

1. Explain why up to 30% of individuals can be removed from the wild boar population, without the risk of destroying it, while the permissible shooting of moose should not exceed 15% of the population size?
(Answer: On average, a female boar gives birth to 4 to 8 (sometimes up to 15) piglets, and a female moose - 1-2. Therefore, the restoration of the wild boar population is proceeding at a faster pace.)

2. Which organisms have a simple and which have a complex population age structure?
(Answer: The simple age structure of populations distinguishes organisms whose life cycle does not exceed one year, and reproduction occurs once in a lifetime and is confined to seasonal changes in environment. These are, for example, annual plants, a number of insect species, etc. Otherwise, the age structure of populations may be complex.)

3. Explain why a significant spring death of adult shrews will lead to a sharp and prolonged decline in the population, while the complete destruction of all adult cockchafers emerging in the spring will not lead to a similar result.
(Answer: The shrew population in the spring is represented exclusively by adult animals of the previous year of birth. Chafer beetles, whose larvae develop in the soil over a period of 3–4 years, have a complex age structure of the population. If adult individuals die one spring, they will be replaced the next year by beetles that have developed from another generation of larvae.)

4. Construct age pyramids reflecting the age composition of the population of Russia (140 million inhabitants) and Indonesia (190 million inhabitants), using the given data.

To be continued

1 The signs “*” and “**” indicate tasks of increased complexity that are cognitive and problematic in nature.

Types of relationships between organisms

Animals and plants, fungi and bacteria do not exist in isolation from each other, but enter into complex relationships. There are several forms of interaction between populations.

Neutralism

Cohabitation of two species in the same territory, which has neither positive nor negative consequences for them.

In neutralism, cohabiting populations of different species do not influence each other. For example, we can say that a squirrel and a bear, a wolf and a cockchafer, do not directly interact, although live in the same forest.

Antibiosis

When both interacting populations or one of them experience a harmful, life-suppressing influence.

Antagonistic relationships can manifest themselves as follows:

1. Competition.

A form of antibiotic relationship in which organisms compete with each other for food resources, sexual partners, shelter, light, etc.

In competition for food, the species whose individuals reproduce faster wins. Under natural conditions, competition between closely related species weakens if one of them switches to new source food (that is, they occupy a different ecological niche). For example, in winter, insectivorous birds avoid competition by searching for food in different places: on tree trunks, in bushes, on stumps, on large or small branches.

Displacement of one population by another: In mixed crops of different types of clover, they coexist, but competition for light leads to a decrease in the density of each of them. Thus, competition that arises between closely related species can have two consequences: either the displacement of one species by another, or different ecological specialization of species, which makes it possible to coexist together.

Suppression of one population by another: Thus, fungi that produce antibiotics suppress the growth of microorganisms. Some plants that can grow on nitrogen-poor soils secrete substances that inhibit the activity of free-living nitrogen-fixing bacteria, as well as the formation of nodules in legumes. In this way, they prevent the accumulation of nitrogen in the soil and the colonization of it by species that require large amounts of it.

3. Amensalism

A form of antibiotic relationship in which one organism interacts with another and suppresses its vital activity, while it itself does not experience any negative influences from the suppressed one (for example, spruce and lower tier plants). A special case is allelopathy - the influence of one organism on another, in which waste products of one organism are released into the external environment, poisoning it and making it unsuitable for the life of another (common in plants).

5. Predation

This is a form of relationship in which an organism of one species uses members of another species as a food source once (by killing them).

Cannibalism – special case predation – killing and eating one’s own kind (found in rats, brown bears, humans).

Symbiosis

A form of relationship in which the participants benefit from cohabitation or at least do not harm each other. Symbiotic relationships also come in a variety of forms.

1. Protocooperation is a mutually beneficial, but optional coexistence of organisms, from which all participants benefit (for example, hermit crab and sea anemone).

2. Mutualism is a form of symbiotic relationship in which either one of the partners or both cannot exist without a cohabitant (for example, herbivorous ungulates and cellulose-degrading microorganisms).

Lichens are an inseparable cohabitation of fungus and algae, when the presence of a partner becomes a condition of life for each of them. The hyphae of the fungus, entwining the cells and filaments of the algae, receive substances synthesized by the algae. Algae extract water and minerals from the fungal hyphae.

Many grasses and trees develop normally only when soil fungi (mycorrhiza) settle on their roots: root hairs do not develop, and the mycelium of the fungus penetrates into the root. Plants receive water and mineral salts from the fungus, and it, in turn, organic matter.

3. Commensalism is a form of symbiotic relationship in which one of the partners benefits from cohabitation, and the other is indifferent to the presence of the first. There are two types of cohabitation:

Housing (some sea anemones and tropical fish). The fish sticks by clinging to large fish (sharks), uses them as a means of transportation and, in addition, feeds on their waste.

The use of structures and body cavities of other species as shelters is widespread. In tropical waters, some fish hide in the respiratory cavity (water lungs) of sea cucumbers (or sea cucumbers, an order of echinoderms). The fry of some fish find refuge under the umbrella of jellyfish and are protected by their stinging threads. To protect the developing offspring, fish use the durable shell of crabs or bivalves. The eggs laid on the gills of the crab develop under conditions of an ideal supply of clean water passing through the gills of the host. Plants also use other species as habitats. These are the so-called epiphytes - plants that settle on trees. These can be algae, lichens, mosses, ferns, flowering plants. Woody plants serve as a place of attachment for them, but not as a source of nutrients.

Freeloading (large predators and scavengers). For example, hyenas follow lions, picking up the remains of their uneaten prey. There may be different spatial relationships between partners. If one partner is outside the cells of the other, they speak of ectosymbiosis, and if inside the cells, they speak of endosymbiosis.

EXAMINATION CARD No. 4
	Types of nutrition of living organisms.
	Theories of the origin of life.

Types of nutrition of living organisms:

There are two types of nutrition of living organisms: autotrophic and heterotrophic.

Autotrophs (autotrophic organisms) are organisms that use carbon dioxide as a carbon source (plants and some bacteria). In other words, these are organisms capable of creating organic substances from inorganic ones - carbon dioxide, water, mineral salts.

Heterotrophs (heterotrophic organisms) are organisms that use organic compounds (animals, fungi and most bacteria) as a carbon source. In other words, these are organisms that are not capable of creating organic substances from inorganic ones, but require ready-made organic substances.

Some living beings, depending on living conditions, are capable of both autotrophy and heterotrophic nutrition. Organisms with a mixed type of nutrition are called mixotrophs. Mixotrophs are organisms that can both synthesize organic substances from inorganic ones and feed on ready-made organic compounds (insectivorous plants, representatives of the euglena algae department, etc.)

"- -" (Competition)- this is an interaction that boils down to the fact that one organism consumes a resource that would be available to another organism and could be consumed by it. One living creature deprives another of part of the resource, which, as a result, grows slower, leaves fewer descendants and has a greater chance of dying. Individuals of the same or different species can deprive each other of a potential resource. In the first case mutual influence can be considered equivalent and symmetrical, since individuals of the same species have more similar resource needs than individuals of different species.

"0 -" (Amensalism)– relationships between individuals of different species, when individuals of one species, often by secreting special substances, have a depressing effect on individuals of another species. Strictly speaking, amensalism can be considered those cases of exposure when one organism produces a harmful effect (for example, releases a toxin) regardless of whether the organism being suppressed is present or not.

“+ -” (Predation)- can be defined as the eating of one organism (prey) by another organism (predator), and the victim must be alive before the predator attacks it. This definition excludes detritophagy (consumption of dead organic matter).

There are different classifications of predators. According to one of them (“taxonomic”), predators (in the proper sense of the word) eat animals, herbivores eat plants, and omnivores eat both.

“+ 0” Commensalism– the basis for this type of relationship can be shared space, substrate, shelter, movement, or most often food. Using the characteristics of the host’s lifestyle or structure, commensalism derives one-sided benefit from this. Its presence usually remains indifferent to the owner (for example, the dwelling of the Mediterranean carp fish in the body cavity of some species of sea cucumbers, which it uses as a refuge).

To the types of relationships listed above, you can add detritophagy (feeding on the remains of organisms). This type has a certain specificity, which is expressed in the fact that decomposers and detritivores do not control the rate at which their resources become available or are renewed; they are completely dependent on the speed with which some other factor (disease, aging) releases the resource that ensures their vital activity.