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Differences from natural ecosystems. Agroecosystems and their features

In addition to natural biogeocenoses and ecosystems, there are communities artificially created by human economic activity - agroecosystems (agrocenosis, agrobiocenosis, agricultural ecosystem).

Agroecosystem(from the Greek agros - field) - a biotic community created and regularly maintained by man in order to obtain agricultural products. Usually includes the totality of organisms living on agricultural land.

Agroecosystems include fields, orchards, vegetable gardens, vineyards, large livestock complexes with adjacent artificial pastures. Feature agroecosystems - low ecological reliability, but high productivity of one (several) species or varieties of cultivated plants or animals. Their main difference from natural ecosystems is their simplified structure and depleted species composition.

Agroecosystems differ from natural ecosystems in a number of ways.

The diversity of living organisms in them is sharply reduced to obtain the highest possible production. On a rye or wheat field, in addition to a cereal monoculture, only a few types of weeds can be found. In a natural meadow, biological diversity is much higher, but biological productivity is many times inferior to a sown field.

Species of agricultural plants and animals in agroecosystems are obtained as a result of the action of artificial rather than natural selection. As a result, there is a sharp narrowing of the genetic base of agricultural crops, which are extremely sensitive to the mass reproduction of pests and diseases.

In natural biocenoses, the primary production of plants is consumed in numerous food chains and returned to the system again. biological cycle in the form of carbon dioxide, water and minerals. Agroecosystems are more open, matter and energy are withdrawn from them with crops, livestock products, and also as a result of soil destruction.

Due to the constant harvesting and disruption of soil formation processes, with long-term cultivation of monoculture on cultivated lands, soil fertility gradually decreases. This position in ecology is called the law of diminishing fertility. Thus, for prudent and rational agriculture, it is necessary to take into account the depletion of soil resources and preserve soil fertility with the help of improved agricultural technology, rational crop rotation and other methods.

Change of vegetation cover in agroecosystems does not occur naturally, but by the will of man, which is not always well reflected in the quality of its abiotic factors. This is especially true for soil fertility.

The main difference between an agroecosystem and natural ecosystems is obtaining additional energy for normal functioning. Supplementary refers to any type of energy that is added to agroecosystems. It can be the muscular strength of a person or animals, various types of fuel for the operation of agricultural machines, fertilizers, pesticides, pesticides, additional lighting etc. The concept of "additional energy" also includes new breeds of domestic animals and varieties of cultivated plants introduced into the structure of agroecosystems.

All agro-ecosystems of fields, orchards, pasture meadows, gardens, greenhouses artificially created in agricultural practice are systems specially supported by man. Agro-ecosystems use their property to produce clean products, since all competitive effects on cultivated plants from weeds are restrained by agrotechnical measures, and the formation of food chains due to pests is stopped by various measures, such as chemical and biological control.

What features of an ecosystem are considered sustainable? First of all, it is a complex, polydominant structure, including the maximum possible number of species and populations under given conditions. The second sign is the maximum biomass. And the last - the relative balance between the income and expenditure of energy. There is no doubt that in such ecosystems the lowest level of productivity is observed: the biomass is large, and the productivity is low. This is due to the fact that the main part of the energy entering the ecosystem goes to maintain life processes.

It should be noted that agroecosystems are extremely unstable communities. They are not capable of self-healing and self-regulation, they are subject to the threat of death from the mass reproduction of pests or diseases. To maintain them, constant human activity is necessary.

Artificial ecosystems (agroecosystems)

Agroecosystems represent a peculiar type of ecosystems. Agroecosystems(agricultural ecosystems) are created by man to obtain high-purity autotrophic products (crops), which differ from natural ones by a number of features:

In them, the diversity of organisms is sharply reduced.
Species cultivated by man are maintained by artificial selection in a state far from their original state and cannot withstand the struggle for existence with wild species without the support of man.
Agroecosystems receive an additional flow of energy, in addition to solar energy, thanks to the activities of people, animals and mechanisms that provide the necessary conditions for the growth of cultivated species. The net primary production (crop) is removed from the ecosystem and does not enter the food chain.

Artificial regulation of pest numbers is, for the most part, a necessary condition for maintaining agroecosystems. Therefore, in agricultural practice, powerful means are used to suppress the number of undesirable species: pesticides, herbicides, etc. Environmental consequences these actions lead, however, to a number of undesirable effects, in addition to those for which they are applied.

In relation to the communities that take shape in agroecosystems, the emphasis is gradually changing in connection with the general development of ecological knowledge. The idea of fragmentation, fragmentation of coenotic connections and the ultimate simplification of agrocenoses is being replaced by an understanding of their complex systemic organization, where a person significantly influences only individual links, and the whole system continues to develop according to natural, natural laws.

From an ecological point of view, it is extremely dangerous to simplify the natural environment of a person, turning the entire landscape into an agricultural one. The main strategy for creating a highly productive and sustainable landscape should be to preserve and increase its diversity.

Along with the maintenance of highly productive fields, special care should be taken to preserve protected areas that are not subject to anthropogenic impact. Reserves with a rich species diversity are a source of species for communities recovering in successional series.

Green revolution

One of the manifestations scientific and technological revolution in agriculture is the "green revolution". green revolution represents a transformation of agriculture based on modern agricultural technology and breeding, this is a period of a radical change in approaches to growing plants and animals. As a result of the first period of this revolution, the yield of grain crops increased by 2-3 times, and the range of products doubled.

The main trends of the second period of the "Green Revolution" were: minimal impact on the environment natural environment, reducing the investment of anthropogenic energy, the use of biological methods of pest control. However, active human intervention in natural ecosystems and the creation of agroecosystems has led to a number of negative consequences: soil degradation, reduced soil fertility, pollution of ecosystems with pesticides.

An ecosystem is a special unity of plants, microorganisms and animals, within which various substances and energy are exchanged between them. Each ecosystem has its own characteristic soil composition, temperature, and other indicators. They are divided into two categories - natural (natural) and artificial (agroecosystems). What are their similarities and differences? Let's figure it out.

Main differences

What is the greatest difference between a natural ecosystem and an agroecosystem? First of all - a variety of species on its territory. The first type (agrocenosis) exists much more long time, has the ability to independently regulate the processes occurring in it. The natural ecosystem, in contrast to the agroecosystem, is more sustainable and stable. The biomass created within its limits is used to enrich its own resources and does not leave the limits of this system. The category of natural ecosystems includes seas, forests, steppes, swamps. The second group includes those systems that are created by human hands.

Agricultural development and natural balance

Since ancient times, when agriculture was just beginning to emerge, man has completely destroyed the vegetation cover in order to grow those species that would be most suitable for food. At the dawn of history, human activity did not disturb the balance in the biochemical cycle. However, modern agriculture uses mostly synthesized energy, cultivates the land mechanically. In the vast majority of cases, fertilizers and pesticides are used to obtain a high yield. All these actions can lead to unpredictable consequences.

Danger to nature

Another difference between an ecosystem and an agroecosystem is the area they occupy. The latter occupy no more than 10% of the total land area. But at the same time they are sources of 90% of food for mankind. Their biological productivity is an order of magnitude higher than that of natural ecosystems. However, agroecosystems are less resilient. What is the difference between a natural ecosystem and an agroecosystem in addition to these factors? One of the most important differences between these two types of systems is that the agroecosystem is soil depleting and can also be hazardous to soil fertility. The first type, on the contrary, forms high-quality soil.

Those man-made systems also produce various wastes and pollutants. They must undergo disinfection, and this happens at the expense of a person. Natural ecosystems are disinfected on their own - no payment or effort from people is needed for this. They also have the ability to keep themselves for a long time. As for agroecosystems, a large amount of costs are required to maintain them.

Rationality in nature management

Often, the answer to the question of what is the difference between an ecosystem and an agroecosystem needs to be prepared by schoolchildren or students of environmental faculties. The main aspect that needs to be voiced when preparing such material is the creation of an agroecosystem by human hands. Those species that are cultivated by human hands are supported by artificial selection. They receive energy flow only due to external actions. Without human support, this type of system disintegrates very quickly and returns to its normal, natural state.

We examined the differences between an ecosystem and an agroecosystem. From this analysis it can be concluded that with a long-term use of natural resources - in particular, with a constant withdrawal of crops - soil fertility is steadily declining. This position in ecological science is called waning fertility. In order to conduct agriculture prudently and rationally, it is necessary to take into account the depletion of soil resources. A person can preserve soil fertility if he uses improved techniques for their cultivation, makes crop rotation rational, and also uses other methods.

How is a natural ecosystem different from an agroecosystem? List of differences

All the differences between these types of systems can be represented as a list:

Agrocenosis created by human hands. A natural ecosystem is formed and functions in nature without intentional human intervention.
Diversity of species is characteristic only of natural ecosystems. On a wheat or rye field created by human hands, you can only find a few types of weeds.
The natural ecosystem constantly receives, accumulates, and also transforms energy. Agrocenosis constantly needs an influx of energy in the form of fertilizers or fuel.
The change of vegetation cover in the agroecosystem occurs at the will of man. In nature, this process proceeds naturally.
Agrocenosis consumes a large amount of water. The natural ecosystem accumulates water, spending it gradually.
The agroecosystem requires significant costs to maintain its existence, and the natural ecosystem has the ability to self-repair.

Ecology deals with the question of how a natural ecosystem differs from an agroecosystem. Those students or schoolchildren who would like to study this issue in more detail can read the special literature. For example, the textbook "General Ecology" by N. M. Chernova and A. M. Bylova, or the publication "Stability and Sustainability of Agroecosystems" by I. Yu. Vinokurov.

December 2, 2017

Nature is multifaceted and beautiful. We can say that this is a whole system that includes both living and inanimate nature. Inside it there are many other different systems that are inferior to it in scale. But not all of them are completely created by nature. In some of them, a person contributes. Anthropogenic factor able to radically change the natural landscape and its orientation.

An agroecosystem is a system that has emerged as a result of anthropogenic activity. People can plow the land, plant the territory with trees, but no matter what we do, we have always been surrounded and will be surrounded by nature. This is some of its peculiarity. How are agroecosystems different from natural ecosystems? This is worth looking into.

Ecological system as a whole

In general, an ecological system is any combination of organic and inorganic components in which there is a circulation of substances. Whether natural or man-made, it is still an ecological system. But still, how do agroecosystems differ from natural ecosystems? About everything in order.

natural ecosystem

A natural system, or, as it is also called, biogeocenosis, is a combination of organic and inorganic components on a plot of the earth's surface with homogeneous natural phenomena: the atmosphere, rocks, hydrological conditions, soils, plants, animals and the world of microorganisms.
The natural system has its own structure, which includes the following components. Producers, or, as they are also called, autotrophs, are all those plants capable of producing organic matter, that is, capable of photosynthesis. Consumers are those who eat plants. It is worth noting that they belong to the first order. In addition, there are consumers and other orders. And, finally, another group is the group of decomposers. It is customary to include various kinds of bacteria, fungi.

The structure of the natural ecosystem

In any ecosystem, food chains, food webs, and trophic levels are distinguished. The food chain is the sequential transfer of energy. A food web is all chains that are interconnected. Trophic levels are the places that organisms occupy in food chains. Producers belong to the very first level, consumers of the first order belong to the second, consumers of the second order to the third, and so on.

A saprophytic chain, or otherwise detrital, begins with dead remains and ends with some kind of animal. There is an omnivorous food chain. The pasture food chain (grazing chain) starts with photosynthetic organisms anyway.

This is all about biogeocenosis. How are agroecosystems different from natural ecosystems?

Agroecosystem

An agroecosystem is an ecosystem created by man. This includes gardens, arable land, vineyards, parks.
Like the previous one, the agroecosystem includes the following blocks: producers, consumers, decomposers. The former include cultivated plants, weeds, plants of pastures, gardens and forest belts. Consumers are all farm animals and humans. The decomposer block is a complex of soil organisms.

Types of agroecosystems

The creation of anthropogenic landscapes includes several types:

agricultural landscapes: arable lands, pastures, irrigated lands, gardens and others;
forest: forest parks, shelterbelts;
water: ponds, reservoirs, canals;
urban: cities, towns;
industrial: mines, quarries.

There is another classification of agroecosystems.

Types of agroecosystems

Depending on the level of economic use, the systems are divided into:

agrosphere (global ecosystem),
agricultural Landscape,
agroecosystem,
agrocenosis.

Depending on the energy natural areas division takes place:

tropical;
subtropical;
moderate;
arctic types.

The first is characterized by high heat supply, continuous vegetation and the predominance of perennial crops. The second - two periods of vegetation, namely summer and winter. The third type has only one growing season, as well as a long dormant period. As for the fourth type, here the cultivation of crops is very difficult due to low temperatures, as well as cold snaps for a long time.

Variety of features

All cultivated plants must have certain properties. Firstly, high ecological plasticity, that is, the ability to produce crops in a wide range of fluctuations in climatic conditions.

Secondly, the heterogeneity of populations, that is, in each of them there should be plants that differ in such characteristics as flowering time, drought resistance, and frost resistance.

Thirdly, precocity - the ability for rapid development, which will outstrip the development of weeds.

Fourth, resistance to fungal and other diseases.

Fifth, resistance to harmful insects.

Comparative characteristics of ecosystems and agroecosystems

In addition, as mentioned above, these ecosystems are very different in a number of other features. Unlike natural, in the agroecosystem, the main consumer is the person himself. It is he who seeks to obtain the maximum primary production(crop) and secondary (livestock). The second consumer are farm animals.

The second difference is that the agroecosystem is formed and regulated by man. Many people ask why an agroecosystem is less resilient than an ecosystem. The thing is that they have a weakly expressed ability for self-regulation and self-renewal. Without human intervention, they exist only for a short time.

The next difference is selection. The stability of the natural ecosystem is ensured by natural selection. In the agroecosystem, it is artificial, provided by man and aimed at obtaining the maximum possible production. The energy received by the agricultural system includes the sun and everything that a person gives: irrigation, fertilizers, and so on.
Natural biogeocenosis feeds only on natural energy. As a rule, plants grown by man include several species, while the natural ecosystem is very diverse.

Different nutritional balance is another difference. The products of plants in a natural ecosystem are used in many food chains, but still return to the system. It turns out the circulation of substances.

How are agroecosystems different from natural ecosystems?

The natural ecosystem (biogeocenosis) and the agroecosystem differ in many ways from each other: plants, consumption, vitality, resistance to pests and diseases, species diversity, type of selection, and many other features.

A human-made ecosystem has both advantages and disadvantages. The natural system, in turn, cannot have any disadvantages. Everything is beautiful and harmonious in it.
When creating artificial systems, a person must carefully treat nature so as not to disturb this harmony.

Main differences

What is the greatest difference between a natural ecosystem and an agroecosystem? First of all - a variety of species on its territory. The first type (agrocenosis) exists for a much longer time, has the ability to independently regulate the processes occurring in it. The natural ecosystem, in contrast to the agroecosystem, is more sustainable and stable. The biomass created within its limits is used to enrich its own resources and does not leave the limits of this system. The category of natural ecosystems includes seas, forests, steppes, swamps. The second group includes those systems that are created by human hands.

Agricultural development and natural balance

Danger to nature

Rationality in nature management

How is a natural ecosystem different from an agroecosystem? List of differences

All the differences between these types of systems can be represented as a list:

Agrocenosis created by human hands. A natural ecosystem is formed and functions in nature without intentional human intervention.
Diversity of species is characteristic only of natural ecosystems. On a wheat or rye field created by human hands, you can only find a few types of weeds.
The natural ecosystem constantly receives, accumulates, and also transforms energy. Agrocenosis constantly needs an influx of energy in the form of fertilizers or fuel.
The change of vegetation cover in the agroecosystem occurs at the will of man. In nature, this process proceeds naturally.
Agrocenosis consumes a large amount of water. The natural ecosystem accumulates water, spending it gradually.
The agroecosystem requires significant costs to maintain its existence, and the natural ecosystem has the ability to self-repair.

Related materials:

Types of ecosystems. General characteristics of ecosystems
Examples of ecosystems. What are the parts of an ecosystem?

Tasks of the C1-C4 part

1. What environmental factors contribute to the regulation of the number of wolves in the ecosystem?

Answer:
1) anthropogenic: deforestation, overshooting;
2) biotic: lack of food, competition, spread of diseases.

2. Determine the type and phase of cell division shown in the figure. What processes take place in this phase?

Answer:
1) the figure shows the metaphase of mitosis;
2) spindle fibers are attached to the centromeres of chromosomes;
3) in this phase, two-chromatid chromosomes line up in the plane of the equator.

3. Why does plowing the soil improve the living conditions of cultivated plants?

Answer:
1) contributes to the destruction of weeds and weakens competition with cultivated plants;
2) contributes to the supply of plants with water and minerals;
3) increases the supply of oxygen to the roots.

4. How is a natural ecosystem different from an agroecosystem?

Answer:
1) great biodiversity and diversity of food relationships and food chains;
2) a balanced circulation of substances;
3) long periods of existence.

5. Expand the mechanisms that ensure the constancy of the number and shape of chromosomes in all cells of organisms from generation to generation?

Answer:
1) due to meiosis, gametes with a haploid set of chromosomes are formed;
2) during fertilization in the zygote, the diploid set of chromosomes is restored, which ensures the constancy of the chromosome set;
3) the growth of the organism occurs due to mitosis, which ensures the constancy of the number of chromosomes in somatic cells.

6. What is the role of bacteria in the cycle of matter?

Answer:
1) heterotrophic bacteria - decomposers decompose organic substances into minerals that are absorbed by plants;
2) autotrophic bacteria (photo, chemotrophs) - producers synthesize organic substances from inorganic ones, ensuring the circulation of oxygen, carbon, nitrogen, etc.

7. What are the characteristics of mossy plants?

Answer:

2) mosses reproduce both sexually and asexually with alternating generations: sexual (gametophyte) and asexual (sporophyte);
3) an adult moss plant is a sexual generation (gametophyte) and a box with spores is asexual (sporophyte);
4) fertilization occurs in the presence of water.

8. Squirrels, as a rule, live in a coniferous forest and feed mainly on spruce seeds. What biotic factors can lead to a reduction in the squirrel population?

9. It is known that the Golgi apparatus is especially well developed in the glandular cells of the pancreas. Explain why.

Answer:
1) in the cells of the pancreas, enzymes are synthesized that accumulate in the cavities of the Golgi apparatus;
2) in the Golgi apparatus, enzymes are packed in the form of bubbles;
3) from the Golgi apparatus, enzymes are carried into the pancreatic duct.

10. Ribosomes from different cells, the entire set of amino acids and the same molecules of mRNA and tRNA were placed in a test tube, and all the conditions for protein synthesis were created. Why will one type of protein be synthesized on different ribosomes in a test tube?

Answer:
1) the primary structure of a protein is determined by the sequence of amino acids;
2) templates for protein synthesis are the same mRNA molecules, in which the same primary protein structure is encoded.

11. What features of the structure are characteristic of representatives of the Chordata type?

Answer:
1) internal axial skeleton;
2) the nervous system in the form of a tube on the dorsal side of the body;
3) gaps in the digestive tube.

12. Clover grows in a meadow, pollinated by bumblebees. What biotic factors can lead to a decline in the clover population?

Answer:
1) a decrease in the number of bumblebees;
2) an increase in the number of herbivorous animals;
3) reproduction of plants of competitors (cereals, etc.).

13. The total mass of mitochondria in relation to the mass of cells of various organs of the rat is: in the pancreas - 7.9%, in the liver - 18.4%, in the heart - 35.8%. Why do the cells of these organs have a different content of mitochondria?

Answer:
1) mitochondria are the energy stations of the cell, ATP molecules are synthesized and accumulated in them;
2) for the intensive work of the heart muscle, a lot of energy is needed, therefore the content of mitochondria in its cells is the highest;
3) in the liver, the number of mitochondria is higher compared to the pancreas, since it has a more intensive metabolism.

14. Explain why beef that has not passed sanitary control is dangerous to eat undercooked or lightly fried.

Answer:
1) in beef meat there may be finns of bovine tapeworm;
2) in the digestive canal, an adult worm develops from the Finn, and the person becomes the final owner.

15. Name the organoid plant cell, shown in the figure, its structures, indicated by the numbers 1-3, and their functions.

Answer:
1) the depicted organoid is a chloroplast;
2) 1 - grana thylakoids, participate in photosynthesis;
3) 2 - DNA, 3 - ribosomes, are involved in the synthesis of their own chloroplast proteins.

16. Why bacteria cannot be classified as eukaryotes?

Answer:
1) in their cells, the nuclear substance is represented by one circular DNA molecule and is not separated from the cytoplasm;
2) do not have mitochondria, Golgi complex, EPS;
3) do not have specialized germ cells, there are no meiosis and fertilization.

17. What changes in biotic factors can lead to an increase in the population of the naked slug that lives in the forest and feeds mainly on plants?

18. In the leaves of plants, the process of photosynthesis proceeds intensively. Does it occur in mature and unripe fruits? Explain the answer.

Answer:
1) photosynthesis occurs in immature fruits (while they are green), since they contain chloroplasts;
2) as they mature, chloroplasts turn into chromoplasts, in which photosynthesis does not occur.

19. What stages of gametogenesis are indicated in the figure by the letters A, B and C? What set of chromosomes do cells have at each of these stages? To the development of what specialized cells does this process lead?

Answer:
1) A - stage (zone) of reproduction (division), diploid cells;
2) B - growth stage (zone), diploid cell;
3) B - stage (zone) of maturation, haploid cells, spermatozoa develop.

20. How do bacterial cells differ in structure from the cells of organisms of other kingdoms of wildlife? List at least three differences.

Answer:
1) there is no formed core, nuclear membrane;
2) a number of organelles are absent: mitochondria, ER, Golgi complex, etc.;
3) have one ring chromosome.

21. Why are plants (producers) considered the initial link in the circulation of substances and the transformation of energy in an ecosystem?

Answer:
1) create organic substances from inorganic;
2) accumulate solar energy;
3) provide organic matter and energy to the organisms of other parts of the ecosystem.

22. What processes ensure the movement of water and minerals through the plant?

Answer:
1) from the root to the leaves, water and minerals move through the vessels due to transpiration, which results in a sucking force;
2) the upward current in the plant is promoted by root pressure, which occurs as a result of the constant flow of water to the root due to the difference in the concentration of substances in the cells and the environment.

23. Consider the cells shown in the figure. Determine what letters denote prokaryotic and eukaryotic cells. Provide evidence for your point of view.

Answer:
1) A - prokaryotic cell, B - eukaryotic cell;
2) the cell in figure A does not have a formed nucleus, its hereditary material is represented by a ring chromosome;
3) the cell in figure B has a well-formed nucleus and organelles.

24. What is the complication of the circulatory system of amphibians compared to fish?

Answer:
1) the heart becomes three-chambered;
2) the second circle of blood circulation appears;
3) the heart contains venous and mixed blood.

25. Why is a mixed forest ecosystem considered more sustainable than a spruce forest ecosystem?

Answer:
1) there are more species in a mixed forest than in a spruce forest;
2) in a mixed forest, food chains are longer and more branched than in a spruce forest;
3) there are more tiers in a mixed forest than in a spruce forest.

26. A section of a DNA molecule has the following composition: GATGAATAGTGCTTC. List at least three consequences that an accidental replacement of the seventh nucleotide of thymine with cytosine (C) can lead to.

Answer:
1) a gene mutation will occur - the codon of the third amino acid will change;
2) in a protein, one amino acid can be replaced by another, as a result, the primary structure of the protein will change;
3) all other protein structures can change, which will lead to the appearance of a new trait in the body.

27. Red algae (crimson) live at great depths. Despite this, photosynthesis occurs in their cells. Explain how photosynthesis occurs if the water column absorbs the rays of the red-orange part of the spectrum.

Answer:
1) for photosynthesis, rays are needed not only in the red, but also in the blue part of the spectrum;
2) purple cells contain a red pigment that absorbs the rays of the blue part of the spectrum, their energy is used in the process of photosynthesis.

28. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. Coelenterates are three-layer multicellular animals. 2. They have a gastric or intestinal cavity. 3. The intestinal cavity includes stinging cells. 4. Coelenterates have a mesh (diffuse) nervous system. 5. All intestinal - free-floating organisms.

1) 1 - coelenterates - two-layer animals;
2)3 - stinging cells are contained in the ectoderm, and not in the intestinal cavity;
3)5 - among the coelenterates there are attached forms.

29. How does gas exchange occur in the lungs and tissues in mammals? What is the reason for this process?

Answer:
1) gas exchange is based on diffusion, which is due to the difference in the concentration of gases (partial pressure) in the air of the alveoli and in the blood;
2) oxygen from the area of high pressure in the alveolar air enters the blood, and carbon dioxide from the area of high pressure in the blood enters the alveoli;
3) in the tissues, oxygen from the high pressure area in the capillaries enters the intercellular substance and then into the cells of the organs. Carbon dioxide from the area of high pressure in the intercellular substance enters the blood.

30. What is the participation of functional groups of organisms in the circulation of substances in the biosphere? Consider the role of each of them in the cycle of substances in the biosphere.

Answer:
1) producers synthesize organic substances from inorganic substances (carbon dioxide, water, nitrogen, phosphorus and other minerals), release oxygen (except for chemotrophs);
2) consumers (and other functional groups) of organisms use and convert organic substances, oxidize them during respiration, absorbing oxygen and releasing carbon dioxide and water;
3) decomposers decompose organic substances to inorganic compounds of nitrogen, phosphorus, etc., returning them to the environment.

31. A section of a DNA molecule encoding a sequence of amino acids in a protein has the following composition: G-A-T-G-A-A-T-A-G-TT-C-T-T-C. Explain the consequences of accidentally adding a guanine (G) nucleotide between the seventh and eighth nucleotides.

Answer:
1) a gene mutation will occur - the codes of the third and subsequent amino acids may change;
2) the primary structure of the protein may change;
3) a mutation can lead to the appearance of a new trait in an organism.

32. What plant organs damage May beetles on different stages individual development?

Answer:
1) plant roots damage larvae;
2) tree leaves damage adult beetles.

33. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. flatworms are three-layered animals. 2. Type Flatworms include white planaria, human roundworm and liver fluke. 3. Flatworms have an elongated flattened body. 4. They have a well-developed nervous system. 5. Flatworms are dioecious animals that lay eggs.

Mistakes made in sentences:
1) 2 - the type of Flatworms does not include the human roundworm, it is a Roundworm;
2) 4 - in flatworms, the nervous system is poorly developed;
3) 5 - Flatworms - hermaphrodites.

34. What is a fetus? What is its significance in the life of plants and animals?

Answer:
1) fruit - generative organ of angiosperms;
2) contains seeds, with the help of which the reproduction and resettlement of plants occurs;
3) the fruits of plants are food for animals.

35. Most of the bird species fly away for the winter from the northern regions, despite their warm-bloodedness. Name at least three factors that cause these animals to migrate.

Answer:
1) food objects of insectivorous birds become unavailable for getting;
2) ice cover on water bodies and snow cover on the ground deprive herbivorous birds of food;
3) change in the length of daylight hours.

36. Which milk, sterilized or freshly milked, will go sour faster under the same conditions? Explain the answer.

Answer:
1) freshly milked milk will sour faster, as it contains bacteria that cause fermentation of the product;
2) when milk is sterilized, cells and spores of lactic acid bacteria die, and milk is stored longer.

37. Find errors in the given text. Indicate the numbers of sentences in which errors were made, explain them.
1. The main classes of the type of arthropods are Crustaceans, Arachnids and Insects. 2. The body of crustaceans and arachnids is divided into head, thorax and abdomen. 3. The body of insects consists of a cephalothorax and an abdomen. 4. Spider antennae don't. 5. Insects have two pairs of antennae, while crustaceans have one pair.

Mistakes made in sentences:
1) 2 - the body of crustaceans and arachnids consists of a cephalothorax and abdomen;
2)3 - the body of insects consists of a head, chest and abdomen;
3-5 - insects have one pair of antennae, and crustaceans have two pairs.

38. Prove that the rhizome of a plant is a modified shoot.

Answer:
1) the rhizome has nodes in which there are rudimentary leaves and buds;
2) at the top of the rhizome is the apical bud, which determines the growth of the shoot;
3) adventitious roots depart from the rhizome;
4) the internal anatomical structure of the rhizome is similar to the stem.

39. Man uses chemicals to control pests. Indicate at least three changes in the life of an oak forest if all herbivorous insects are destroyed in it by a chemical method. Explain why they will happen.

Answer:
1) the number of insect pollinated plants will decrease sharply, since herbivorous insects are pollinators of plants;
2) the number of insectivorous organisms (consumers of the second order) will sharply decrease or they will disappear due to disruption of food chains;
3) part of the chemicals used to kill insects will enter the soil, which will lead to disruption of plant life, death of soil flora and fauna, all violations can lead to the death of oak forests.

40. Why can antibiotic treatment lead to bowel dysfunction? Name at least two reasons.

Answer:
1) antibiotics kill beneficial bacteria that live in the human intestine;
2) fiber breakdown, water absorption and other processes are disturbed.

41. What part of the sheet is indicated in the figure by the letter A and what structures does it consist of? What are the functions of these structures?

1) the letter A denotes a vascular fibrous bundle (vein), the bundle includes vessels, sieve tubes, mechanical tissue;
2) vessels provide water transport to the leaves;
3) sieve tubes provide transport of organic substances from leaves to other organs;
4) mechanical tissue cells give strength and are the framework of the sheet.

42. What are characteristics mushroom kingdom?

Answer:
1) the body of fungi consists of filaments - hyphae, forming a mycelium;
2) reproduce sexually and asexually (spores, mycelium, budding);
3) grow throughout life;
4) in the cell: the shell contains a chitin-like substance, a reserve nutrient - glycogen.

43. In a small reservoir formed after the flood of the river, the following organisms were found: ciliates-shoes, daphnia, white planarians, a large pond snail, cyclops, hydras. Explain whether this body of water can be considered an ecosystem. Give at least three pieces of evidence.

Answer:
The named temporary reservoir cannot be called an ecosystem, since in it:
1) there are no producers;
2) there are no decomposers;
3) there is no closed circulation of substances and food chains are broken.

44. Why is a note placed under the tourniquet, which is applied to stop bleeding from large blood vessels, indicating the time of its application?

Answer:
1) after reading the note, you can determine how much time has passed since the tourniquet was applied;
2) if after 1-2 hours it was not possible to deliver the patient to the doctor, then the tourniquet should be loosened for a while. This will prevent tissue necrosis.

45. Name the structures of the spinal cord, indicated in the figure by numbers 1 and 2, and describe the features of their structure and function.

Answer:
1) 1 - gray matter, formed by the bodies of neurons;
2) 2 - white matter, formed by long processes of neurons;
3) gray matter performs a reflex function, white matter - a conductive function.

46. What role do salivary glands play in digestion in mammals? List at least three functions.

Answer:
1) the secretion of the salivary glands moistens and disinfects food;
2) saliva is involved in the formation of the food bolus;
3) saliva enzymes contribute to the breakdown of starch.

47. As a result of volcanic activity, an island was formed in the ocean. Describe the sequence of ecosystem formation on a newly formed piece of land. List at least three items.

Answer:
1) the first to settle are microorganisms and lichens that provide soil formation;
2) plants settle on the soil, the spores or seeds of which are carried by wind or water;
3) as vegetation develops, animals appear in the ecosystem, primarily arthropods and birds.

48. Experienced gardeners apply fertilizer to the grooves located along the edges of the near-stem circles of fruit trees, and do not distribute them evenly. Explain why.

Answer:
1) the root system grows, the suction zone moves behind the root tip;
2) roots with a developed suction zone - root hairs - are located along the edges of the near-stem circles.

49. What modified shoot is shown in the picture? Name the elements of the structure, indicated in the figure by the numbers 1, 2, 3, and the functions that they perform.

Answer:
1) bulb;
2) 1 - juicy scaly leaf, in which nutrients and water are stored;
3) 2 - adventitious roots that ensure the absorption of water and minerals;
4) 3 - kidney, ensures the growth of the shoot.

50. What are the features of the structure and life of mosses? List at least three items.

Answer:
1) most mosses are leafy plants, some of them have rhizoids;
2) mosses have a poorly developed conducting system;
3) mosses reproduce both sexually and asexually, with alternation of generations: sexual (gametophyte) and asexual (sporophyte); an adult moss plant is a sexual generation, and a spore box is asexual.

51. As a result forest fire burned part of the spruce forest. Explain how it will self-heal. List at least three steps.

Answer:
1) herbaceous light-loving plants develop first;
2) then shoots of birch, aspen, pine appear, the seeds of which fell with the help of the wind, a small-leaved or pine forest is formed.
3) under the canopy of light-loving species, shade-tolerant spruces develop, which subsequently completely crowd out other trees.

52. To establish the cause of a hereditary disease, the patient's cells were examined and a change in the length of one of the chromosomes was found. What research method allowed to establish the cause of this disease? What kind of mutation is it associated with?

Answer:
1) the cause of the disease is established using the cytogenetic method;
2) the disease is caused by a chromosomal mutation - the loss or addition of a chromosome fragment.

53. What letter in the figure indicates the blastula in the development cycle of the lancelet. What are the features of blastula formation?

Answer:
1) the blastula is designated by the letter G;
2) the blastula is formed during the crushing of the zygote;
3) the size of the blastula does not exceed the size of the zygote.

54. Why are fungi isolated in a special kingdom of the organic world?

Answer:
1) the body of mushrooms consists of thin branching threads - hyphae, forming a mycelium, or mycelium;
2) mycelium cells store carbohydrates in the form of glycogen;
3) fungi cannot be attributed to plants, since their cells do not have chlorophyll and chloroplasts; the wall contains chitin;
4) mushrooms cannot be attributed to animals, since they absorb nutrients from the entire surface of the body, and do not swallow them in the form of food lumps.

55. In some forest biocenoses, mass shooting of diurnal birds of prey was carried out to protect chicken birds. Explain how this event affected the number of chickens.

Answer:
1) at first, the number of chickens increased, since their enemies (naturally regulating the number) were destroyed;
2) then the number of chickens decreased due to lack of food;
3) the number of sick and weakened individuals increased due to the spread of diseases and the absence of predators, which also affected the decrease in the number of chickens.

56. The color of the fur of a white hare changes throughout the year: in winter the hare is white, and in summer it is gray. Explain what type of variability is observed in an animal and what determines the manifestation of this trait.

Answer:
1) a manifestation of modification (phenotypic, non-hereditary) variability is observed in a hare;
2) the manifestation of this trait is determined by changes in environmental conditions (temperature, day length).

57. Name the stages of embryonic development of the lancelet, indicated in the figure by the letters A and B. Expand the features of the formation of each of these stages.
A B

Answer:
1) A - gastrula - the stage of a two-layer embryo;
2) B - neurula, has the beginnings of a future larva or adult organism;
3) the gastrula is formed by invagination of the blastula wall, and in the neurula, the neural plate is first laid, which serves as a regulator for laying the rest of the organ systems.

58. What are the main features of the structure and vital activity of bacteria. List at least four features.

Answer:
1) bacteria - pre-nuclear organisms that do not have a formalized nucleus and many organelles;
2) according to the method of nutrition, bacteria are heterotrophs and autotrophs;
3) high rate of reproduction by division;
4) anaerobes and aerobes;
5) unfavorable conditions are experienced in a state of dispute.

59. What is the difference between the ground-air environment and the water?

Answer:
1) oxygen content;
2) differences in temperature fluctuations (wide amplitude of fluctuations in the ground-air environment);
3) the degree of illumination;
4) density.

Answer:
1) seaweed has the ability to accumulate the chemical element iodine;
2) Iodine is essential for normal thyroid function.

61. Why is a shoe ciliate cell considered an integral organism? What organelles of ciliates-shoes are indicated in the figure by the numbers 1 and 2 and what functions do they perform?

Answer:
1) the ciliate cell performs all the functions of an independent organism: metabolism, reproduction, irritability, adaptation;
2) 1 - a small nucleus, participates in the sexual process;
3) 2 - a large core, regulates vital processes.

61. What are the features of the structure and life of fungi? List at least three features.

62. Explain the harm to plants caused by acid rain. Give at least three reasons.

Answer:
1) directly damage the organs and tissues of plants;
2) pollute the soil, reduce fertility;
3) reduce the productivity of plants.

63. Why are passengers advised to suck on lollipops when taking off or landing an airplane?

Answer:
1) a rapid change in pressure during takeoff or landing of an aircraft causes discomfort in the middle ear, where the initial pressure on the eardrum lasts longer;
2) swallowing movements improve the access of air to the auditory (Eustachian) tube, through which the pressure in the middle ear cavity equalizes with the pressure in the environment.

64. How does the circulatory system of arthropods differ from the circulatory system of annelids? Indicate at least three signs that prove these differences.

Answer:
1) in arthropods, the circulatory system is open, and in annelids it is closed;
2) arthropods have a heart on the dorsal side;
3) annelids do not have a heart, its function is performed by an annular vessel.

65. What type is the animal shown in the picture? What is indicated by numbers 1 and 2? Name other representatives of this type.

Answer:
1) to the type of intestinal;
2) 1 - ectoderm, 2 - intestinal cavity;
3) coral polyps, jellyfish.

66. What are the morphological, physiological and behavioral adaptations to environmental temperature in warm-blooded animals?

Answer:
1) morphological: heat-insulating covers, subcutaneous fat layer, changes in the surface of the body;
2) physiological: increased intensity of evaporation of sweat and moisture during breathing; narrowing or dilation of blood vessels, changes in the level of metabolism;
3) behavioral: construction of nests, burrows, changes in daily and seasonal activity depending on the temperature of the environment.

67. How is the receipt of genetic information from the nucleus to the ribosome?

Answer:
1) mRNA synthesis occurs in the nucleus in accordance with the principle of complementarity;
2) mRNA - a copy of the DNA section containing information about the primary structure of the protein moves from the nucleus to the ribosome.

68. What is the complication of ferns in comparison with mosses? Give at least three signs.

Answer:
1) ferns have roots;
2) in ferns, unlike mosses, a developed conductive tissue has formed;
3) in the development cycle of ferns, the asexual generation (sporophyte) prevails over the sexual (gametophyte), which is represented by the outgrowth.

69. Name the embryonic layer of a vertebrate animal, indicated in the figure by the number 3. What type of tissue and what organs are formed from it.

Answer:
1) germinal layer - endoderm;
2epithelial tissue (intestinal and respiratory epithelium);
3) organs: intestines, digestive glands, respiratory organs, some endocrine glands.

70. What role do birds play in the biocenosis of the forest? Give at least three examples.

Answer:
1) regulate the number of plants (distribute fruits and seeds);
2) regulate the number of insects, small rodents;
3) serve as food for predators;
4) fertilize the soil.

71. What is the protective role of leukocytes in the human body?

Answer:
1) leukocytes are capable of phagocytosis - devouring and digesting proteins, microorganisms, dead cells;
2) leukocytes are involved in the production of antibodies that neutralize certain antigens.

72. Find errors in the given text. Indicate the numbers of the proposals in which they are made, correct them.
According to the chromosome theory of heredity:
1. Genes are located on chromosomes in a linear order. 2. Everyone occupies a certain place - an allele. 3. Genes on one chromosome form a linkage group. 4. The number of linkage groups is determined by the diploid boron of chromosomes. 5. Violation of gene linkage occurs in the process of conjugation of chromosomes in the prophase of meiosis.

Mistakes made in sentences:
1)2 - location of the gene - locus;
2)4 - the number of linkage groups is equal to the haploid set of chromosomes;
3)5 - disruption of gene linkage occurs during crossing over.

73. Why do some scientists refer to green euglena as a plant, and others as an animal? List at least three reasons.

Answer:
1) capable of heterotrophic nutrition, like all animals;
2) capable of active movement in search of food, like all animals;
3) contains chlorophyll in the cell and is capable of autotrophic nutrition, like plants.

74. What processes take place at the stages of energy metabolism?

Answer:
1) at the preparatory stage, complex organic substances are split into less complex ones (biopolymers - to monomers), energy is dissipated in the form of heat;
2) in the process of glycolysis, glucose is broken down to pyruvic acid (or lactic acid, or alcohol) and 2 ATP molecules are synthesized;
3) at the oxygen stage, pyruvic acid (pyruvate) is broken down to carbon dioxide and water and 36 ATP molecules are synthesized.

75. In a wound formed on the human body, bleeding eventually stops, but suppuration may occur. Explain what properties of blood this is due to.

Answer:
1) bleeding stops due to blood clotting and the formation of a blood clot;
2) suppuration is due to the accumulation of dead leukocytes that have carried out phagocytosis.

76. Find errors in the given text, correct them. Indicate the numbers of sentences in which errors were made, explain them.
1. Great importance in the structure and life of organisms have proteins. 2. These are biopolymers whose monomers are nitrogenous bases. 3. Proteins are included plasma membrane. 4. Many proteins perform an enzymatic function in the cell. 5. In protein molecules, hereditary information about the characteristics of an organism is encrypted. 6. Protein and tRNA molecules are part of ribosomes.

Mistakes made in sentences:
1) 2 - protein monomers are amino acids;
2)5 - hereditary information about the characteristics of the organism is encrypted in DNA molecules;
3)6- ribosomes contain rRNA molecules, not tRNA.

77. What is myopia? In what part of the eye is the image focused in a nearsighted person? What is the difference between congenital and acquired forms of myopia?

Answer:
1) myopia is a disease of the organs of vision, in which a person does not distinguish distant objects;
2) in a nearsighted person, the image of objects appears in front of the retina;
3) with congenital myopia, the shape of the eyeball changes (lengthens);
4) acquired myopia is associated with a change (increase) in the curvature of the lens.

78. What is the difference between the skeleton of the human head and the skeleton of the head of great apes? List at least four differences.

Answer:
1) dominance brain department skulls over facial;
2) reduction of the jaw apparatus;
3) the presence of a chin protrusion on the lower jaw;
4) reduction of superciliary arches.

79. Why is the volume of urine excreted by the human body per day not equal to the volume of liquid drunk during the same time?

Answer:
1) part of the water is used by the body or is formed in metabolic processes;
2) part of the water evaporates through the respiratory organs and sweat glands.

80. Find errors in the given text, correct them, indicate the numbers of the sentences in which they are made, write down these sentences without errors.
1. Animals are heterotrophic organisms; they feed on ready-made organic substances. 2. There are unicellular and multicellular animals. 3. All multicellular animals have bilateral body symmetry. 4. Most of them have developed various organs of locomotion. 5. Only arthropods and chordates have a circulatory system. 6. Postembryonic development in all multicellular animals is direct.

Mistakes made in sentences:
1) 3 - not all multicellular animals have bilateral symmetry of the body; for example, in coelenterates it is radial (radial);
2) 5 - the circulatory system is also present in annelids and mollusks;
3) 6 - direct postembryonic development is not inherent in all multicellular animals.

81. What is the importance of blood in human life?

Answer:
1) performs a transport function: delivery of oxygen and nutrients to tissues and cells, removal of carbon dioxide and metabolic products;
2) fulfills protective function due to the activity of leukocytes and antibodies;
3) participates in the humoral regulation of the vital activity of the organism.

82. Use information about the early stages of embryogenesis (zygote, blastula, gastrula) to confirm the sequence of development of the animal world.

Answer:
1) the zygote stage corresponds to a unicellular organism;
2) the blastula stage, where cells are not differentiated, is similar to colonial forms;
3) the embryo at the gastrula stage corresponds to the structure of the intestinal cavity (hydra).

83. The introduction of large doses of drugs into a vein is accompanied by their dilution with saline (0.9% NaCl solution). Explain why.

Answer:
1) the introduction of large doses of drugs without dilution can cause a sharp change in the composition of the blood and irreversible phenomena;
2) the concentration of physiological saline (0.9% NaCl solution) corresponds to the concentration of salts in the blood plasma and does not cause the death of blood cells.

84. Find errors in the given text, correct them, indicate the numbers of the sentences in which they are made, write down these sentences without errors.
1. Animals of the arthropod type have an outer chitinous cover and jointed limbs. 2. The body of most of them consists of three sections: the head, chest and abdomen. 3. All arthropods have one pair of antennae. 4. Their eyes are complex (faceted). 5. The circulatory system of insects is closed.

Mistakes made in sentences:
1)3 - not all arthropods have one pair of antennae (arachnoids do not have them, and crustaceans have two pairs each);
2) 4 - not all arthropods have compound (compound) eyes: in arachnids they are simple or absent, in insects, along with compound eyes, they can be simple;
3-5 - the circulatory system in arthropods is not closed.

85. What are the functions of the human digestive system?

Answer:
1) mechanical processing of food;
2) chemical processing of food;
3) movement of food and removal of undigested residues;
4) absorption of nutrients, mineral salts and water into the blood and lymph.

86. What characterizes biological progress in flowering plants? List at least three features.

Answer:
1) a wide variety of populations and species;
2) wide settlement on the globe;
3) adaptability to life in different environmental conditions.

87. Why should food be chewed thoroughly?

Answer:
1) well-chewed food is quickly saturated with saliva in the oral cavity and begins to be digested;
2) well-chewed food is quickly saturated with digestive juices in the stomach and intestines and therefore easier to digest.

88. Find errors in the given text. Indicate the numbers of the proposals in which they are made, correct them.
1. A population is a collection of freely interbreeding individuals of the same species that inhabit a common territory for a long time. 2. Different populations of the same species are relatively isolated from each other, and their individuals do not interbreed. 3. The gene pool of all populations of the same species is the same. 4. The population is the elementary unit of evolution. 5. A group of frogs of the same species living in a deep puddle for one summer is a population.

Mistakes made in sentences:
1)2 - populations of the same species are partially isolated, but individuals of different populations can interbreed;
2)3 — gene pools of different populations of the same species are different;
3)5 - a group of frogs is not a population, since a group of individuals of the same species is considered a population if it a large number generations occupy the same space.

89. Why is it recommended to drink salted water in summer with prolonged thirst?

Answer:
1) in summer, sweating increases in a person;
2) mineral salts are excreted from the body with sweat;
3) salted water restores the normal water-salt balance between the tissues and the internal environment of the body.

90. What proves that a person belongs to the class of mammals?

Answer:
1) the similarity of the structure of organ systems;
2) the presence of hairline;
3) the development of the embryo in the uterus;
4) feeding offspring with milk, caring for offspring.

91. What processes maintain the constancy of the chemical composition of human blood plasma?

Answer:
1) processes in buffer systems maintain the reaction of the medium (pH) at a constant level;
2) neurohumoral regulation of the chemical composition of plasma is carried out.

92. Find errors in the given text. Indicate the numbers of the proposals in which they are made, explain them.
1. A population is a collection of freely interbreeding individuals different types, inhabiting a common territory for a long time. 2. The main group characteristics of the population are the number, density, age, sex and spatial structures. 3. The totality of all the genes of a population is called the gene pool. 4. Population is a structural unit of living nature. 5. The number of populations is always stable.

Mistakes made in sentences:
1)1 - a population is a collection of freely interbreeding individuals of the same species, inhabiting the common territory of the population for a long time;
2)4 - the population is a structural unit of the species;
3)5 - the number of populations can change in different seasons and years.

93. What structures of the integument of the body provide protection for the human body from the effects of environmental temperature factors? Explain their role.

Answer:
1) subcutaneous fatty tissue protects the body from cooling;
2) sweat glands form sweat, which, when evaporated, protects against overheating;
3) the hair on the head protects the body from cooling and overheating;
4) changing the lumen of skin capillaries regulates heat transfer.

94. Give at least three progressive biological features of a person, which he acquired in the process of long evolution.

Answer:
1) an increase in the brain and cerebral part of the skull;
2) upright posture and corresponding changes in the skeleton;
3) liberation and development of the hand, opposition of the thumb.

95. What division of meiosis is similar to mitosis? Explain how it is expressed and what set of chromosomes in the cell leads to.

Answer:
1) similarity with mitosis is observed in the second division of meiosis;
2) all phases are similar, sister chromosomes (chromatids) diverge to the poles of the cell;
3) the resulting cells have a haploid set of chromosomes.

96. What is the difference between arterial bleeding and venous bleeding?

Answer:
1) with arterial bleeding, scarlet blood;
2) it shoots out of the wound with a strong jet, a fountain.

97. The scheme of what process occurring in the human body is shown in the figure? What underlies this process and how does the composition of the blood change as a result? Explain the answer.
capillary

Answer:
1) the figure shows a diagram of gas exchange in the lungs (between the pulmonary vesicle and the blood capillary);
2) gas exchange is based on diffusion - the penetration of gases from a place with high pressure to a place with less pressure;
3) as a result of gas exchange, the blood is saturated with oxygen and turns from venous (A) to arterial (B).

98. What effect does hypodynamia (low motor activity) have on the human body?

Answer:
hypodynamia leads to:
1) to a decrease in the level of metabolism, an increase in adipose tissue, overweight;
2) weakening of the skeletal and cardiac muscles, increasing the load on the heart and reducing the endurance of the body;
3) venous blood stagnation in the lower extremities, vasodilation, circulatory disorders.

(Other formulations of the answer are allowed that do not distort its meaning.)

99. What are the characteristics of plants that live in arid conditions?

Answer:
1) the root system of plants penetrates deep into the soil, reaches the groundwater or is located in the surface layer of the soil;
2) in some plants, water is stored in leaves, stems and other organs during drought;
3) the leaves are covered with a wax coating, pubescent or modified into spines or needles.

100. What is the reason for the need for iron ions to enter the human blood? Explain the answer.

Answer:

2) erythrocytes provide transport of oxygen and carbon dioxide.

101. Through what vessels and what kind of blood enters the chambers of the heart, indicated in the figure by numbers 3 and 5? With what circle of blood circulation is each of these structures of the heart connected?

Answer:
1) venous blood enters the chamber marked with the number 3 from the superior and inferior vena cava;
2) the chamber marked with the number 5 receives arterial blood from the pulmonary veins;
3) the chamber of the heart, indicated by the number 3, is associated with a large circle of blood circulation;
4) the chamber of the heart, indicated by the number 5, is associated with the pulmonary circulation.

102. What are vitamins, what is their role in the life of the human body?

Answer:
1) vitamins - biologically active organic substances needed in small quantities;
2) they are part of enzymes, participating in metabolism;
3) increase the body's resistance to adverse effects external environment, stimulate growth, development of the organism, restoration of tissues and cells.

103. The body shape of the Kalima butterfly resembles a leaf. How did a similar body shape form in a butterfly?

Answer:
1) the appearance in individuals of various hereditary changes;
2) preservation by natural selection of individuals with a modified body shape;
3) reproduction and distribution of individuals with a body shape resembling a leaf.

104. What is the nature of most enzymes and why do they lose their activity when the level of radiation increases?

Answer:
1) most enzymes are proteins;
2) under the action of radiation, denaturation occurs, the structure of the protein-enzyme changes.

105. Find errors in the given text. Indicate the numbers of proposals in which they are made, correct them.
1. Plants, like all living organisms, feed, breathe, grow, reproduce. 2. According to the method of nutrition, plants are classified as autotrophic organisms. 3. When breathing, plants absorb carbon dioxide and release oxygen. 4. All plants reproduce by seeds. 5. Plants, like animals, grow only in the first years of life.

Mistakes made in sentences:
1) 3 - when breathing, plants absorb oxygen and release carbon dioxide;
2-4 - only flowering and gymnosperms reproduce by seeds, and algae, mosses, ferns - by spores;
3-5 - plants grow throughout their lives, have unlimited growth.

106. What is the reason for the need for iron ions to enter the human blood? Explain the answer.

Answer:
1) iron ions are part of the hemoglobin of erythrocytes;
2) erythrocyte hemoglobin provides transport of oxygen and carbon dioxide, as it is able to bind to these gases;
3) the supply of oxygen is necessary for the energy metabolism of the cell, and carbon dioxide is its final product to be removed.

107. Explain why people of different races are classified as the same species. Give at least three pieces of evidence.

Answer:
1) the similarity of the structure, life processes, behavior;
2) genetic unity - the same set of chromosomes, their structure;
3) interracial marriages produce offspring capable of reproduction.

108. In ancient india the suspect in the crime was offered to swallow a handful of dry rice. If he did not succeed, the guilt was considered proven. Give a physiological justification for this process.

Answer:
1) swallowing is a complex reflex act, which is accompanied by salivation and irritation of the root of the tongue;
2) with strong excitement, salivation is sharply inhibited, the mouth becomes dry, and the swallowing reflex does not occur.

109. Find errors in the given text. Indicate the numbers of the proposals in which they are made, explain them.
1. The composition of the food chain of biogeocenosis includes producers, consumers and decomposers. 2. The first link in the food chain are consumers. 3. Consumers in the world accumulate energy absorbed in the process of photosynthesis. 4. In the dark phase of photosynthesis, oxygen is released. 5. Reducers contribute to the release of energy accumulated by consumers and producers.

Mistakes made in sentences:
1) 2 - the first link is the producers;
2) 3 - consumers are not capable of photosynthesis;
3)4 - oxygen is released in the light phase of photosynthesis.

110. What are the causes of anemia in humans? List at least three possible reasons.

Answer:
1) large blood loss;
2) malnutrition (lack of iron and vitamins, etc.);
3) violation of the formation of erythrocytes in the hematopoietic organs.

111. The wasp fly is similar in color and body shape to a wasp. Name the type of its protective device, explain its significance and the relative nature of fitness.

Answer:
1) type of adaptation - mimicry, imitation of the color and shape of the body of an unprotected animal to a protected one;
2) resemblance to a wasp warns a possible predator about the danger of being stung;
3) the fly becomes the prey of young birds that have not yet developed a reflex to the wasp.

112. Compose food chain, using all the following objects: humus, spider, hawk, great tit, housefly. Determine the consumers of the third order in the compiled chain.

Answer:
1) humus -> housefly -> spider-cross -> great tit -> hawk;
2) consumer of the third order - great tit.

113. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. Annelids are the most highly organized animals of the cut of other types of worms. 2. Annelids have an open circulatory system. 3. The body of the annelids consists of identical segments. 4. There is no body cavity in annelids. 5. Nervous system annelids is represented by the peripharyngeal ring and the dorsal nerve chain.

Mistakes made in sentences:
1) 2 - Annelids have a closed circulatory system;
2) 4 - Annelids have a body cavity;
3-5 - the nerve chain is located on the ventral side of the body.

114. Name at least three aromorphoses in terrestrial plants that allowed them to be the first to master the land. Justify the answer.

Answer:
1) the emergence of integumentary tissue - the epidermis with stomata - contributing to protection against evaporation;
2) the appearance of a conducting system that ensures the transport of substances;
3) the development of a mechanical tissue that performs a supporting function.

115. Explain what is connected with big variety marsupials in Australia and their absence on other continents.

Answer:
1) Australia separated from other continents during the heyday of marsupials before the appearance of placental animals (geographical isolation);
2) the natural conditions of Australia contributed to the divergence of signs of marsupials and active speciation;
3) on other continents, marsupials were replaced by placental mammals.

116. In what cases does a change in the sequence of DNA nucleotides not affect the structure and functions of the corresponding protein?

Answer:
1) if, as a result of a nucleotide substitution, another codon appears that codes for the same amino acid;
2) if the codon formed as a result of a nucleotide substitution encodes a different amino acid, but with similar chemical properties, which does not change the structure of the protein;
3) if nucleotide changes occur in intergenic or non-functioning DNA regions.

117. Why is the relationship between pike and perch in the river ecosystem considered competitive?

Answer:
1) are predators, eat similar food;
2) live in the same reservoir, need similar conditions for life, mutually oppress each other.

118. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. The main classes of the type of arthropods are Crustaceans, Arachnids and Insects. 2. Insects have four pairs of legs, and arachnids have three pairs. 3. The crayfish has simple eyes, and the cross-spider has complex eyes. 4. In arachnids, spider warts are located on the abdomen. 5. Spider-cross and Maybug breathe with the help of lung sacs and trachea.

Mistakes made in sentences:
1) 2 - insects have three pairs of legs, and arachnids - four pairs;
2) 3 - crayfish has compound eyes, and the cross-spider has simple eyes;
3)5 - y Maybug there are no lung sacs, and there are only tracheas.

119. What are the features of the structure and life of cap mushrooms? List at least four features.

Answer:
1) have a mycelium and a fruiting body;
2) reproduce by spores and mycelium;
3) according to the method of nutrition - heterotrophs;
4) most form mycorrhiza.

120. What aromorphoses allowed the ancient amphibians to master the land.

Answer:
1) the appearance of pulmonary respiration;
2) the formation of dissected limbs;
3) the appearance of a three-chambered heart and two circles of blood circulation.

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