Agroecosystem- a biotic community deliberately planned by man, created and regularly maintained by man for the purpose of obtaining agricultural products. Usually includes a set of organisms living on agricultural lands. Feature agroecosystems – low ecological reliability, but high productivity of one or several plant species (or varieties of cultivated plants).
Agroecosystems include fields, gardens, vegetable gardens, vineyards, large livestock complexes with adjacent pastures, etc.
Agroecosystems, like natural ecosystems, are characterized by a set of their constituent species (ᴛ.ᴇ. have a certain composition of organisms) and certain relationships between organisms and the environment. In an agrocenosis, the same food chains develop as in natural ecosystems.
Agrocenosis- an artificially created and constantly maintained by man biotic community with high productivity of one or several selected species (varieties, breeds) of plants and animals. Eg, the trophic structure of a rye field is determined by a set producers(rye, weeds), consumers(insects, birds, voles, foxes) and decomposers(fungi, microorganisms).
At the same time, in difference from natural ecosystem An obligatory link in the food chain here is a person who forms agrocenoses based on their practical significance - and ensures their high productivity.
The main goal of creating an agroecosystem– rational use of those biological resources of the agroecosystem that are directly involved in human activity – sources food products, technological raw materials, medicines. This also includes species specially cultivated by humans that are objects of agricultural production: fish farming, fur farming, special cultivation forest crops, as well as species used for industrial technologies.
Agroecosystems are created by humans to obtain high yields - pure production of autotrophs. Summarizing everything that has already been said above about agroecosystems, we emphasize the following main ones: differences from natural ones:
1. The diversity of species in them is sharply reduced: a decrease in the species of cultivated plants reduces and species diversity animal population of the biocenosis; the species diversity of animals bred by humans is negligible compared to nature; cultivated pastures (with underseeding of grasses) are similar in species diversity to agricultural fields.
2. Species of plants and animals cultivated by humans “evolve” due to artificial selection and are uncompetitive in the fight against wild species without human support.
3. Agroecosystems receive additional energy subsidized by humans, in addition to solar energy.
4. Pure products (harvest) are removed from the ecosystem and do not enter the food chain of the biocenosis, and its partial use by pests, losses during harvesting, which can also end up in natural trophic chains, are suppressed by man in every possible way.
5. Ecosystems of fields, gardens, pastures, vegetable gardens and other agrocenoses are simplified systems supported by humans in the early stages of succession, and they are just as unstable and incapable of self-regulation as natural pioneer communities, and therefore cannot exist without human support .
Today arable land Over 30% of the land is occupied by pastures, and human activities to maintain these systems are becoming a global environmental factor.
Despite the significant simplification of agroecosystems, they still retain many biocenotic connections, which ultimately affect the fate of the crop. A comparison of information about the fauna and flora of wheat fields shows the enormous complexity of even an extremely simple agrocenosis; more than a thousand species are preserved here.
The conditions that agricultural crop fields should ideally meet—to be highly productive and at the same time stable—are incompatible from an environmental point of view. In natural ecosystems, primary plant production is consumed in numerous food chains and is returned in the form of mineral salts and carbon dioxide to the biological cycle system. By protecting the crop from its natural consumers, alienating it and replacing it with organic and mineral fertilizers, we break many food chains and imbalance the community. Essentially, all efforts to create high dense production of individual crops are a struggle “against nature”, which require large amounts of labor and material resources.
The concept of “agroecosystem” appeared quite recently. Man has already studied the principles of the formation of ecosystems and established the level of harm that customary, irrational farming causes to him and nature. Therefore, a well-thought-out agroecosystem should provide humanity with food and not harm the remaining ecosystems on Earth.
Agroecosystem– these are types of ecosystems that were created by man in order to provide his family and the population of the country with food and raw materials for various industries.
Ecosystem is a historically established community of plants, fungi, animals, microorganisms in a certain sector of the hydrosphere, on the continent, in the lower layer of the atmosphere or in top layer soil.
An agroecosystem is a specific area on land or sea in which humans have organized the agricultural process in a special way. The condition for this area to receive the right to be called an agroecosystem must be rational land use, livestock farming or cultivation of certain crops in the sea. That is Agriculture should not be custom and extensive, but as intense as possible, with a thoughtful process of returning the used power and energy of nature to the general cycle of organic and mineral substances on the planet.
To ensure such a cycle, the agroecosystem must be multidisciplinary and multifaceted. For example, to a plot of arable land it is necessary to “attach” a pasture, a meadow, orchard and small livestock complex. All connections between the components of the agroecosystem are organized and carried out by humans.
Ecosystem is a basic concept of ecology. An ecosystem can be natural or anthropogenic. For example, a savanna ecosystem, an ecosystem of Lake Baikal, or an ecosystem of a wasteland behind a house.
An ecosystem consists of two types of components - biotic and abiotic. Biotic components are the set of living organisms that inhabit our system. In this case, we will call them producers, consumers of different levels and decomposers. Abiotic components are the basis for the formation of an ecosystem: the aquatic environment or land underlying rocks, temperature and humidity indicators, temperature conditions.
There are different types of connections between the components of the ecosystem that have developed historically over a fairly long period of time. Therefore, time, competition and natural selection are the main creators of the ecosystem.
Agroecosystems and their differences from natural ecosystems
Man, in the competitive struggle for survival and to satisfy his ever-increasing needs, is forced to change natural ecosystems and even destroy them, perhaps without wanting to.
In order to rational use biological resources, humanity creates agricultural ecosystems, or agroecosystems, designed to obtain high yields - pure products of autotrophs. The main differences between agroecosystems and natural ecosystems are:
a decrease in the diversity of species in them, since the species diversity of plants and animals bred by humans is negligible compared to nature;
species of plants and animals cultivated by humans “evolve” due to artificial selection and are uncompetitive in the fight against wild species without human support;
agroecosystems receive additional (except solar) energy subsidized by humans;
pure products (harvest) are removed from the ecosystem and do not enter the biocenosis chain;
agroecosystems are simplified systems, unstable and incapable of self-regulation.
In agroecosystems, excessive growth in the form of an “ecological explosion” occurs much more often. individual species. For example, in the 19th century. An “explosion” of the late blight fungus population destroyed potatoes in France and caused famine, and the Colorado potato beetle spread from America to European Russia. To prevent such phenomena from occurring, it is necessary to artificially regulate the number of pests with the rapid suppression of those that are just trying to get out of control. Simplification of the natural environment of man from an ecological point of view is very dangerous. Therefore, it is impossible to turn the entire landscape into an agricultural one; it is necessary to preserve and increase its diversity, leaving untouched protected areas that could be a source of species for the restoration of communities.
Man also creates complex urban systems, pursuing a good goal - to improve living conditions, and not only by simply “protecting himself” from limiting factors, but also by creating for himself a new artificial environment that increases the comfort of life. However, this leads to a separation of man from the natural environment and to the disruption of natural ecosystems.
Urban settlements are an unstable natural-anthropogenic system consisting of architectural and construction objects and severely disturbed natural ecosystems. As cities develop, they become increasingly differentiated functional areas- industrial, residential, forest park. Industrial zones are areas of concentration industrial facilities various industries that are the main sources of environmental pollution. Residential zones are areas where residential buildings are concentrated, administrative buildings, objects of culture, education, etc. A forest park zone is a green zone around and inside the city, cultivated by man, that is, adapted for mass recreation, sports, and entertainment. Forest park zones, city parks and other areas of territory designated and specially adapted for people's recreation are called recreational zones.
Wednesday, surrounding a person in urban conditions, is a combination of abiotic and social factors, jointly and directly influencing people and their economy. It is divided into natural environment the natural environment transformed by man and the artificial environment. In general, the urban environment is part of the technosphere, that is, the biosphere, radically transformed by man into technical and man-made objects.
In addition to the ground part of the landscape, the surface part of the lithosphere, which is commonly called the geological environment, also falls into the orbit of human economic activity. The geological environment is rocks, groundwater, which is affected by economic activity person. The geographical and geological environments of urban systems have been most strongly changed and have essentially become artificial. Here there is an increasing isolation of economic and production cycles from natural metabolism (biogeochemical
Tasks of parts C1-C4
1. What environmental factors contribute to the regulation of the number of wolves in the ecosystem?
Answer:
1) anthropogenic: reduction of forest area, excessive hunting;
2) biotic: lack of food, competition, spread of diseases.
2. Determine the type and phase of division of the cell shown in the figure. What processes occur in this phase?
Answer:
1) the figure shows metaphase of mitosis;
2) spindle threads are attached to the centromeres of chromosomes;
3) in this phase, bichromatid chromosomes line up in the equatorial plane.
3. Why does plowing the soil improve the living conditions of cultivated plants?
Answer:
1) promotes the destruction of weeds and reduces competition with cultivated plants;
2) promotes the supply of plants with water and minerals;
3) increases the supply of oxygen to the roots.
4. How does a natural ecosystem differ from an agroecosystem?
Answer:
1) great biodiversity and diversity of food connections and food chains;
2) balanced circulation of substances;
3) long periods of existence.
5. Reveal the mechanisms that ensure the constancy of the number and shape of chromosomes in all cells of organisms from generation to generation?
Answer:
1) thanks to meiosis, gametes with a haploid set of chromosomes are formed;
2) during fertilization, the diploid set of chromosomes is restored in the zygote, 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 substances?
Answer:
1) heterotrophic bacteria - decomposers decompose organic substances into minerals, which 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 features are characteristic 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 the sexual generation (gametophyte) and the capsule with spores is asexual (sporophyte);
4) fertilization occurs in the presence of water.
8. Squirrels, as a rule, live in coniferous forests and feed mainly on spruce seeds. What biotic factors can lead to a decline 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) pancreatic cells synthesize enzymes that accumulate in the cavities of the Golgi apparatus;
2) in the Golgi apparatus, enzymes are packaged in the form of vesicles;
3) from the Golgi apparatus, enzymes are carried into the pancreatic duct.
10. Ribosomes from different cells, the entire set of amino acids and identical molecules of mRNA and tRNA were placed in a test tube, and all conditions were created for protein synthesis. 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) the templates for protein synthesis are identical mRNA molecules, in which the same primary protein structure is encoded.
11. What structural features 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) cracks in the digestive tube.
12. Clover grows in a meadow and is pollinated by bumblebees. What biotic factors can lead to a decline in clover populations?
Answer:
1) decrease in the number of bumblebees;
2)increase in the number of herbivorous animals;
3) propagation of competitor plants (cereals, etc.).
13. The total mass of mitochondria in relation to the mass of cells of various rat organs is: in the pancreas - 7.9%, in the liver - 18.4%, in the heart - 35.8%. Why do the cells of these organs have different mitochondrial content?
Answer:
1) mitochondria are the energy stations of the cell; ATP molecules are synthesized and accumulated in them;
2) for intensive work cardiac muscle needs a lot of energy, 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 intense metabolism.
14. Explain why beef that has not passed sanitary control is dangerous to eat undercooked or lightly cooked.
Answer:
1) beef meat may contain bovine tapeworms;
2) an adult worm develops from the finna in the digestive canal, and the person becomes the final host.
15. Name the plant cell organelle shown in the figure, its structures indicated by numbers 1-3, and their functions.
Answer:
1) the organelle depicted is a chloroplast;
2) 1 - grana thylakoids, involved in photosynthesis;
3) 2 - DNA, 3 - ribosomes, participate in the synthesis of the chloroplast's own proteins.
16. Why can’t bacteria 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, the Golgi complex, or the ER;
3) do not have specialized germ cells, there is no meiosis and fertilization.
17. What changes in biotic factors can lead to an increase in the population of a naked slug that lives in a forest and feeds mainly on plants?
18. The process of photosynthesis occurs intensively in the leaves of plants. Does it occur in ripe and unripe fruits? Explain your answer.
Answer:
1) photosynthesis occurs in unripe 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? What specialized cells does this process lead to the development of?
Answer:
1)A - stage (zone) of reproduction (division), diploid cells;
2)B - stage (zone) of growth, diploid cell;
3) B - stage (zone) of maturation, the cells are haploid, sperm develop.
20. How do bacterial cells differ in structure from the cells of organisms in other kingdoms of living nature? List at least three differences.
Answer:
1) there is no formed nucleus, nuclear envelope;
2) a number of organelles are missing: mitochondria, EPS, Golgi complex, etc.;
3) have one ring chromosome.
21. Why are plants (producers) considered the initial link in the cycle of substances and energy conversion in the ecosystem?
Answer:
1) create organic substances from inorganic ones;
2) accumulate solar energy;
3) provide organic substances and energy to organisms in other parts of the ecosystem.
22. What processes ensure the movement of water and minerals throughout the plant?
Answer:
1) from the root to the leaves, water and minerals move through the vessels due to transpiration, as a result of which suction force arises;
2) the upward flow in the plant is facilitated by root pressure, which arises as a result of the constant flow of water into the root due to the difference in the concentration of substances in the cells and the environment.
23. Look at the cells shown in the figure. Determine which letters represent 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 formed nucleus and organelles.
24. What is the complexity of the circulatory system of amphibians compared to fish?
Answer:
1) the heart becomes three-chambered;
2) a second circle of blood circulation appears;
3) the heart contains venous and mixed blood.
25. Why is a mixed forest ecosystem considered more stable than a spruce forest ecosystem?
Answer:
1) there are more species in the mixed forest than in the spruce forest;
2) in a mixed forest the 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 can result from an accidental replacement of the seventh nucleotide of thymine with cytosine (C).
Answer:
1) a gene mutation will occur - the codon of the third amino acid will change;
2) in a protein, one amino acid may be replaced by another, as a result of which the primary structure of the protein will change;
3) all other protein structures may change, which will lead to the appearance of a new trait in the body.
27. Red algae (purple algae) live at great depths. Despite this, photosynthesis occurs in their cells. Explain why photosynthesis occurs if the water column absorbs rays from the red-orange part of the spectrum.
Answer:
1) photosynthesis requires rays not only from the red, but also from the blue part of the spectrum;
2) the cells of scarlet mushrooms contain a red pigment that absorbs rays from 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 the sentences in which errors were made and 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 reticular (diffuse) nervous system. 5. All coelenterates are free-swimming 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 of mammals? What causes this process?
Answer:
1) gas exchange is based on diffusion, which is caused by the difference in gas concentration (partial pressure) in the air of the alveoli and in the blood;
2) oxygen from the area high pressure in the alveolar air enters the blood, and carbon dioxide from the area of high blood pressure enters the alveoli;
3) in tissues, oxygen from the area of high pressure in the capillaries enters the intercellular substance and then into the cells of the organs. Carbon dioxide from the high pressure area in the intercellular substance enters the blood.
30. What is the participation of functional groups of organisms in the cycle 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 transform organic substances, oxidize them during respiration, absorbing oxygen and releasing carbon dioxide and water;
3) decomposers decompose organic substances to inorganic compounds nitrogen, phosphorus, etc., returning them to the environment.
31. The section of the DNA molecule encoding the 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 nucleotide (G) 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 are damaged by cockchafers at different stages of individual development?
Answer:
1) plant roots are damaged by larvae;
2) tree leaves are damaged by adult beetles.
33. Find errors in the given text. Indicate the numbers of the sentences in which errors were made and correct them.
1. Flatworms are three-layered animals. 2. The phylum 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.
Errors were made in the sentences:
1)2 - the human roundworm is not classified as a Flatworm; it is a Roundworm;
2)4 - in flatworms the nervous system is poorly developed;
3)5 - Flatworms are hermaphrodites.
34. What is a fruit? What is its significance in the life of plants and animals?
Answer:
1) fruit - the generative organ of angiosperms;
2) contains seeds with the help of which plants reproduce and disperse;
3) plant fruits are food for animals.
35. Most bird species fly away from the northern regions for the winter, despite their warm-blooded nature. Indicate at least three factors that cause these animals to fly.
Answer:
1) food items of insectivorous birds become unavailable for obtaining;
2) ice cover on reservoirs and snow cover on the ground deprive herbivorous birds of food;
3) change in daylight hours.
36. Which milk, sterilized or freshly milked, will sour faster under the same conditions? Explain your answer.
Answer:
1) freshly milked milk will sour faster, since it contains bacteria that cause fermentation of the product;
2) when milk is sterilized, the cells and spores of lactic acid bacteria die, and the milk lasts longer.
37. Find errors in the given text. Indicate the numbers of the sentences in which errors were made and explain them.
1. The main classes of phylum arthropods are Crustaceans, Arachnids and Insects. 2. The body of crustaceans and arachnids is divided into the head, thorax and abdomen. 3. The body of insects consists of a cephalothorax and abdomen. 4. Arachnids do not have antennae. 5. Insects have two pairs of antennae, and crustaceans have one pair.
Errors were made in the 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 rudimentary leaves and buds are located;
2) at the top of the rhizome there is an apical bud that determines the growth of the shoot;
3) adventitious roots extend from the rhizome;
4) the internal anatomical structure of the rhizome is similar to the stem.
39. To combat insect pests, people use chemicals. Indicate at least three changes in the life of the oak forest if it chemically all herbivorous insects will be destroyed. Explain why they will happen.
Answer:
1) the number of insect-pollinated plants will sharply decrease, since herbivorous insects are plant pollinators;
2) the number of insectivorous organisms (consumers of the 2nd order) will sharply decrease or they will disappear due to disruption of food chains;
3)part chemical substances, which were used to destroy insects, will get into the soil, which will lead to disruption of plant life, death of soil flora and fauna, all violations can lead to the death of the oak forest.
40. Why can treatment with antibiotics lead to intestinal dysfunction? Give at least two reasons.
Answer:
1)antibiotics kill beneficial bacteria, living in the human intestines;
2) the breakdown of fiber, water absorption and other processes are disrupted.
41.Which part of the sheet is indicated in the figure by the letter A and what structures does it consist of? What functions do these structures perform?
1) the letter A denotes a vascular-fibrous bundle (vein), the bundle includes vessels, sieve tubes, and mechanical tissue;
2) vessels provide transport of water to the leaves;
3) sieve tubes provide transport of organic substances from leaves to other organs;
4) mechanical tissue cells provide strength and serve as the framework of the leaf.
42. What are characteristic features kingdom of mushrooms?
Answer:
1) the body of fungi consists of threads - hyphae, forming a mycelium;
2) reproduce sexually and asexually (spores, mycelium, budding);
3) grow throughout life;
4) in the cell: the membrane contains a chitin-like substance, a reserve nutrient is glycogen.
43. In a small reservoir formed after a river flood, the following organisms were found: slipper ciliates, daphnia, white planaria, large pond snail, cyclops, hydra. Explain whether this body of water can be considered an ecosystem. Provide at least three pieces of evidence.
Answer:
The named temporary reservoir cannot be called an ecosystem, since it contains:
1) there are no producers;
2) there are no decomposers;
3) there is no closed circulation of substances and food chains are disrupted.
44. Why is a note placed under a tourniquet, which is applied to stop bleeding from large blood vessels, indicating the time it was applied?
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 death.
45. Name the structures 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 the 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 participates in the formation of the food bolus;
3) salivary enzymes promote the breakdown of starch.
47. As a result of volcanic activity, an island was formed in the ocean. Describe the sequence of formation of an ecosystem on a newly formed landmass. Please provide at least three items.
Answer:
1) the first to settle are microorganisms and lichens, which ensure the formation of soil;
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 fertilizers to the grooves located along the edges tree trunk circles fruit trees, rather than distributing them evenly. Explain why.
Answer:
1) the root system grows, the suction zone moves behind the root apex;
2) roots with a developed absorption zone - root hairs - are located at the edges of the trunk circles.
49. What modified shoot is shown in the figure? Name the structural elements indicated in the figure by numbers 1, 2, 3, and the functions that they perform.
Answer:
1) onion;
2)1 - a succulent scale-like leaf in which nutrients and water are stored;
3)2 - adventitious roots, ensuring the absorption of water and minerals;
4)3 - bud, ensures shoot growth.
50. What are the structural features and vital functions of mosses? Please provide 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 alternating generations: sexual (gametophyte) and asexual (sporophyte); An adult moss plant is the sexual generation, and the spore capsule is asexual.
51. As a result of a forest fire, part of the spruce forest burned out. Explain how its self-healing will occur. List at least three steps.
Answer:
1) herbaceous, light-loving plants develop first;
2) then birch, aspen, and pine shoots appear, the seeds of which fell with the help of the wind, and a small-leaved or pine forest is formed.
3) under the canopy of light-loving species, shade-tolerant spruce trees develop, which subsequently completely displace 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 discovered. What research method allowed us to establish the cause? of this disease? What type of mutation is it associated with?
Answer:
1) the cause of the disease was 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 fragmentation of the zygote;
3) the size of the blastula does not exceed the size of the zygote.
54. Why are mushrooms classified as a special kingdom of the organic world?
Answer:
1) the body of mushrooms consists of thin branching threads - hyphae, forming mycelium, or mycelium;
2) mycelial cells store carbohydrates in the form of glycogen;
3) mushrooms cannot be classified as plants, since their cells do not have chlorophyll and chloroplasts; the wall contains chitin;
4) mushrooms cannot be classified as animals, since they absorb nutrients over the entire surface of the body, and do not swallow them in the form of food lumps.
55. In some forest biocenoses, to protect chicken birds, mass shooting of daytime birds of prey was carried out. Explain how this event affected the number of chickens.
Answer:
1) at first, the number of chickens increased, as their enemies were destroyed (naturally regulating the number);
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 lack of predators, which also affected the decrease in the number of chickens.
56. The color of the white hare’s fur changes throughout the year: in winter the hare is white, and in summer it is gray. Explain what type of variability is observed in the animal and what determines the manifestation of this trait.
Answer:
1) the hare exhibits modification (phenotypic, non-hereditary) variability;
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 letters A and B. Reveal the features of the formation of each of these stages.
A B
Answer:
1) A - gastrula - stage of a two-layer embryo;
2) B - neurula, has the rudiments of a future larva or adult organism;
3) the gastrula is formed by invagination of the wall of the blastula, and in the neurula the neural plate is first formed, which serves as a regulator for the formation of other organ systems.
58. Name the main features of the structure and activity of bacteria. List at least four features.
Answer:
1) bacteria - prenuclear organisms that do not have a formed 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. How does the land-air environment differ from the water environment?
Answer:
1) oxygen content;
2) differences in temperature fluctuations (wide amplitude of fluctuations in the ground-air environment);
3) degree of illumination;
4) density.
Answer:
1) seaweed has the ability to accumulate chemical element iodine;
2) iodine is necessary for normal function thyroid gland.
61. Why is a ciliate slipper cell considered an integral organism? What organelles of the ciliate slipper are indicated in the figure by 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 - small nucleus, participates in the sexual process;
3) 2 - large nucleus, regulates vital processes.
61. What are the structural features and vital functions of mushrooms? Please indicate at least three characteristics.
62. Explain how acid rain harms plants. Give at least three reasons.
Answer:
1) directly damage plant organs and tissues;
2) pollute the soil, reduce fertility;
3)reduce plant productivity.
63. Why are passengers recommended to suck lollipops when taking off or landing an airplane?
Answer:
1) rapid changes in pressure during takeoff or landing of an airplane cause discomfort in the middle ear, where the initial pressure on the eardrum persists longer;
2) swallowing movements improve air access to the auditory (Eustachian) tube, through which the pressure in the middle ear cavity is equalized 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) arthropods have an open circulatory system, while annelids have a closed circulatory system;
2) arthropods have a heart on the dorsal side;
3) annelids do not have a heart; its function is performed by a ring vessel.
65. What type of animal is the one shown in the picture? What is indicated by numbers 1 and 2? Name other representatives of this type.
Answer:
1) to the type Coelenterates;
2) 1 - ectoderm, 2 - intestinal cavity;
3) coral polyps, jellyfish.
66. How are morphological, physiological and behavioral adaptations to environmental temperature manifested in warm-blooded animals?
Answer:
1) morphological: heat-insulating covers, subcutaneous layer of fat, 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 metabolic levels;
3) behavioral: construction of nests, burrows, changes in daily and seasonal activity depending on environmental temperature.
67. How admission is carried out 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 a DNA section containing information about the primary structure of the protein, moves from the nucleus to the ribosome.
68. How is the complexity of ferns compared to mosses? Give at least three signs.
Answer:
1) the ferns have roots;
2) ferns, unlike mosses, have developed developed conductive tissue;
3) in the development cycle of ferns, the asexual generation (sporophyte) predominates over the sexual generation (gametophyte), which is represented by the prothallus.
69. Name the germ layer of a vertebrate animal, indicated in the figure by number 3. What type of tissue and what organs are formed from it.
Answer:
1) germ layer - endoderm;
2 epithelial tissue (epithelium of the intestines and respiratory organs);
3) organs: intestines, digestive glands, respiratory organs, some endocrine glands.
70. What role do birds play in the forest biocenosis? Give at least three examples.
Answer:
1) regulate the number of plants (distribute fruits and seeds);
2) regulate the number of insects and 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 take part in the production of antibodies that neutralize certain antigens.
72. Find errors in the given text. Indicate the numbers of the sentences in which they are made, correct them.
According to the chromosomal theory of heredity:
1. Genes are located on chromosomes in linear order. 2. Each occupies a specific place - an allele. 3. Genes on one chromosome form a linkage group. 4. The number of linkage groups is determined by the diploid number of chromosomes. 5. Disruption of gene cohesion occurs during the process of chromosome conjugation in the prophase of meiosis.
Errors were made in the 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 classify green euglena as a plant, and others as an animal? Provide 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 occur at the stages of energy metabolism?
Answer:
1)on preparatory stage complex organic substances are broken down into less complex ones (biopolymers - into monomers), energy is dissipated in the form of heat;
2) in the process of glycolysis, glucose is broken down into pyruvic acid (or lactic acid, or alcohol) and 2 ATP molecules are synthesized;
3) at the oxygen stage, pyruvic acid (pyruvate) is broken down into carbon dioxide and water and 36 ATP molecules are synthesized.
75. In a wound formed on the human body, bleeding stops over time, 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 caused by the accumulation of dead leukocytes that have carried out phagocytosis.
76. Find errors in the given text and correct them. Indicate the numbers of sentences in which errors were made and explain them.
1. Great importance proteins are present in the structure and functioning of organisms. 2. These are biopolymers whose monomers are nitrogenous bases. 3. Proteins are part of the plasma membrane. 4. Many proteins perform enzymatic functions in the cell. 5. Protein molecules are encrypted hereditary information about the signs of the body. 6. Protein and tRNA molecules are part of ribosomes.
Errors were made in the sentences:
1)2 - monomers of proteins are amino acids;
2)5 - hereditary information about the characteristics of an organism is encrypted in DNA molecules;
3)6- ribosomes contain rRNA molecules, not tRNA.
77. What is myopia? In what part of the eye does the image focus in a nearsighted person? What is the difference between congenital and acquired forms of myopia?
Answer:
1) myopia is a disease of the visual organs in which a person has difficulty distinguishing distant objects;
2) in a myopic 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. How does the skeleton of the human head differ from the skeleton of the head of great apes? List at least four differences.
Answer:
1) predominance of the cerebral part of the skull over the facial part;
2) reduction of the jaw apparatus;
3) the presence of a chin protuberance on the lower jaw;
4)reduction of brow ridges.
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 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 movement. 5. Only arthropods and chordates have a circulatory system. 6. Postembryonic development in all multicellular animals is direct.
Errors were made in the 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) performs a protective function due to the activity of leukocytes and antibodies;
3) participates in the humoral regulation of the body’s vital functions.
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 the cells are not differentiated, is similar to colonial forms;
3) the embryo at the gastrula stage corresponds to the structure of the coelenterate (hydra).
83. The injection of large doses of drugs into a vein is accompanied by their dilution with physiological solution (0.9% NaCl solution). Explain why.
Answer:
1) administration of large doses of drugs without dilution can cause a sharp change in blood composition and irreversible phenomena;
2) the concentration of saline solution (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 were made, write down these sentences without errors.
1. Animals of the arthropod type have an external chitinous cover and jointed limbs. 2. The body of most of them consists of three sections: 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.
Errors were made in the sentences:
1)3 - not all arthropods have one pair of antennae (arachnids do not have them, and crustaceans have two pairs);
2)4 - not all arthropods have complex (compounded) eyes: in arachnids they are simple or absent, in insects they can have simple eyes along with complex eyes;
3)5 - the circulatory system of arthropods is not closed.
85. What are the functions digestive system person?
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. How is biological progress characterized in flowering plants? Specify at least three signs.
Answer:
1) a wide variety of populations and species;
2) wide distribution 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 soaked in saliva oral cavity and begins to digest;
2) well-chewed food is quickly saturated with digestive juices in the stomach and intestines and is therefore easier to digest.
88. Find errors in the given text. Indicate the numbers of the sentences 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 one 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 pool for one summer constitutes a population.
Errors were made in the sentences:
1)2 - populations of one species are partially isolated, but individuals from different populations can interbreed;
2)3 - the 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 occupies the same space for a large number of generations.
89. Why is it recommended to drink salted water in the summer when you are thirsty for a long time?
Answer:
1) in summer a person sweats more;
2) mineral salts are removed from the body through sweat;
3) salted water restores the normal water-salt balance between tissues and the internal environment of the body.
90. What proves that a person belongs to the class of mammals?
Answer:
1) similarity in the structure of organ systems;
2) the presence of hair;
3) development of the embryo in the uterus;
4) feeding the offspring with milk, caring for the offspring.
91. What processes maintain consistency? chemical composition 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 sentences in which they are made and 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 a population are size, density, age, sex and spatial structure. 3. The totality of all genes in a population is called the gene pool. 4. A population is a structural unit of living nature. 5. Population numbers are always stable.
Errors were made in the sentences:
1)1 - a population is a collection of freely interbreeding individuals of the same species that inhabit the general territory of the population for a long time;
2)4 - the population is a structural unit of the species;
3)5 - population numbers can change in different seasons and years.
93. What structures of the body cover protect 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 produce sweat, which, when evaporated, protects against overheating;
3) hair on the head protects the body from cooling and overheating;
4) changes in the lumen of skin capillaries regulate heat transfer.
94. Give at least three progressive biological characteristics of a person that he acquired in the process of long evolution.
Answer:
1) enlargement of 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. Which division of meiosis is similar to mitosis? Explain how it is expressed and what set of chromosomes in the cell it leads to.
Answer:
1) similarities with mitosis are 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, the blood is scarlet;
2) it shoots out from the wound with a strong stream, a fountain.
97. A diagram 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 your 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 physical inactivity (low physical activity) have on the human body?
Answer:
physical inactivity leads to:
1) to a decrease in the level of metabolism, an increase in adipose tissue, excess body weight;
2) weakening of skeletal and cardiac muscles, increased load on the heart and decreased endurance of the body;
3) stagnation of venous blood in the lower extremities, vasodilation, circulatory disorders.
(Other wording of the answer is allowed without distorting its meaning.)
99. What characteristics do plants living in arid conditions have?
Answer:
1) the root system of plants penetrates deeply into the soil, reaching groundwater or located in the surface layer of soil;
2) in some plants, water is stored in leaves, stems and other organs during drought;
3) the leaves are covered with a waxy 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 your answer.
Answer:
2) red blood cells provide transport of oxygen and carbon dioxide.
101. Through what vessels and what kind of blood does the chambers of the heart, indicated in the figure by numbers 3 and 5? Which circulatory system is each of these heart structures connected to?
Answer:
1) the chamber marked with number 3 receives venous blood from the superior and inferior vena cava;
2) the chamber indicated by the number 5 receives arterial blood from the pulmonary veins;
3) the heart chamber, indicated by the number 3, is connected to the systemic circulation;
4) the heart chamber, indicated by the number 5, is connected to 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 body, restoration of tissues and cells.
103. The body shape of the Kalima butterfly resembles a leaf. How did the butterfly develop such a body shape?
Answer:
1) the appearance of various hereditary changes in individuals;
2)saving natural selection individuals with altered 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 influence of radiation, denaturation occurs, the structure of the protein-enzyme changes.
105. Find errors in the given text. Indicate the numbers of the proposals in which they were made, correct them.
1. Plants, like all living organisms, eat, breathe, grow, and reproduce. 2. According to the method of nutrition, plants are classified as autotrophic organisms. 3. When plants respire, they absorb carbon dioxide and release oxygen. 4. All plants reproduce by seeds. 5. Plants, like animals, grow only in the first years of life.
Errors were made in the sentences:
1)3 - when plants respire, they absorb oxygen and release carbon dioxide;
2)4 - only flowering plants and gymnosperms reproduce by seeds, and algae, mosses, and ferns reproduce 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 your answer.
Answer:
1) iron ions are part of the hemoglobin of erythrocytes;
2) hemoglobin of erythrocytes ensures the transport of oxygen and carbon dioxide, as it is able to bind with these gases;
3) the supply of oxygen is necessary for the energy metabolism of the cell, and carbon dioxide is its final product that must be removed.
107. Explain why people of different races are classified as the same species. Provide at least three pieces of evidence.
Answer:
1) similarity in structure, life processes, behavior;
2) genetic unity - the same set of chromosomes, their structure;
3) interracial marriages produce offspring capable of reproduction.
108.V ancient india the suspect in the crime was offered to swallow a handful of dry rice. If he failed, guilt was considered proven. Give a physiological basis 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 sentences in which they are made and explain them.
1. The food chain of biogeocenosis includes producers, consumers and decomposers. 2. The first link in the food chain is consumers. 3. Consumers in the light accumulate energy absorbed in the process of photosynthesis. 4. In the dark phase of photosynthesis, oxygen is released. 5. Decomposers contribute to the release of energy accumulated by consumers and producers.
Errors were made in the 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) poor nutrition (lack of iron and vitamins, etc.);
3) disruption of the formation of red blood cells in the hematopoietic organs.
111. The wasp fly is similar in color and body shape to the wasp. Name its type protective device, explain its meaning and the relative nature of fitness.
Answer:
1) type of adaptation - mimicry, imitation of the color and body shape of an unprotected animal to a protected one;
2) the resemblance to a wasp warns a possible predator of the danger of being stung;
3) the fly becomes prey for young birds that have not yet developed a reflex to the wasp.
112. Make up food chain, using all the objects named below: humus, cross spider, hawk, great tit, housefly. Identify third-order consumers in the constructed chain.
Answer:
1) humus -> housefly -> cross spider -> great tit -> hawk;
2) consumer of the third order - the great tit.
113. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. Annelids- These are the most highly organized animals of the cut of other types of worms. 2. Annelids have an open-ended circulatory system. 3. Body ringworm consists of identical segments. 4. Annelids have no body cavity. 5. Nervous system annelids are represented by the peripharyngeal ring and the dorsal nerve cord.
Errors were made in the 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 land plants that allowed them to be the first to develop land. Justify your answer.
Answer:
1) the appearance of integumentary tissue—the epidermis with stomata—promoting protection from evaporation;
2) the emergence of a conducting system that ensures the transport of substances;
3) development of mechanical tissue that performs a supporting function.
115. Explain why there is a large diversity of marsupial mammals 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 marsupial characters 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 replacement, another codon encoding the same amino acid arises;
2) if the codon formed as a result of a nucleotide replacement 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, feed on similar food;
2) live in the same body of water, need similar living conditions, 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 phylum arthropods are Crustaceans, Arachnids and Insects. 2. Insects have four pairs of legs, and arachnids have three pairs. 3. The crayfish has simple eyes, while the cross spider has complex eyes. 4. Arachnids have arachnoid warts on their abdomen. 5. The cross spider and the cockchafer breathe using lung sacs and tracheas.
Errors were made in the sentences:
1)2 - insects have three pairs of legs, and arachnids have four pairs;
2)3 - the crayfish has compound eyes, and the cross spider has simple eyes;
3)5 - the cockchafer does not have lung sacs, but only trachea.
119. What are the features of the structure and life activity cap mushrooms? Name 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 mycorrhizae.
120. What aromorphoses allowed ancient amphibians to develop land.
Answer:
1) the appearance of pulmonary breathing;
2) formation of dismembered limbs;
3) the appearance of a three-chambered heart and two circulation circles.
An ecosystem is a special unity of plants, microorganisms and animals, within which exchange occurs between them various substances and energy. Each ecosystem has its own 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.
How does a natural ecosystem differ most from an agroecosystem? First of all, the diversity of species on its territory. The first type (agrocenosis) exists for a much longer time and has the ability to independently regulate the processes occurring in it. A natural ecosystem, unlike an agroecosystem, is more sustainable and stable. The biomass created within its boundaries is used to enrich its own resources and does not leave the boundaries of this system. The category of natural ecosystems includes seas, forests, steppes, and swamps. The second group includes those systems that are created by human hands.
Since ancient times, when agriculture was just beginning to emerge, people completely destroyed vegetation in order to grow those species that would be most suitable for food. At the dawn of history, human activity did not upset the balance in the biochemical cycle. However, modern agriculture uses mostly synthesized energy, cultivates the land by mechanical means. In the vast majority of cases, fertilizers and pesticides are used to obtain high yields. All these actions can lead to unpredictable consequences.
Another difference between an ecosystem and an agroecosystem is the area they occupy. The latter occupy no more than 10% of total area sushi. But at the same time they are the sources of 90% of food for humanity. Their biological productivity is an order of magnitude higher than that of natural ecosystems. However, agroecosystems are less resilient. How does a natural ecosystem differ from an agroecosystem in addition to the listed factors? One of the most important differences between these two types of systems is that the agroecosystem depletes the soil and can also be hazardous to soil fertility. The first type, on the contrary, forms high-quality soil.
Those systems that are man-made also produce various wastes and pollutants. They must undergo disinfection, and this occurs at the expense of the person. Natural ecosystems are disinfected on their own - this does not require any payment or effort on the part of people. They also have the ability to preserve themselves for a long time. As for agroecosystems, their maintenance requires a large number of costs.
Often the answer to the question of what is the difference between an ecosystem and an agroecosystem needs to be prepared for 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 maintained through artificial selection. They receive energy flow only through external actions. Without human support, this type of system very quickly disintegrates and returns to its normal, natural state.
We looked at the differences between an ecosystem and an agroecosystem. From this analysis we can conclude: with long-term use natural resources- in particular, with constant harvesting, soil fertility is steadily declining. This position is in environmental science is called diminishing returns. In order to conduct agriculture prudently and rationally, it is necessary to take into account the factor of depletion of soil resources. A person can maintain soil fertility if he uses improved technology for their cultivation, makes crop rotation rational, and also uses other techniques.
All the differences between these types of systems can be presented in the form of a list:
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 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.
Related materials:
