Assignments for OGE 9th grade biology. GIA online tests in biology

The state final certification for ninth grade graduates is currently voluntary; you can always refuse and take the usual traditional exams.

Why then is the OGE (GIA) form more attractive for 9th grade graduates of 2019? Carrying out direct certification in this new form allows you to obtain an independent assessment of schoolchildren’s preparation. All OGE (GIA) tasks are presented in the form of a special form, including questions with a choice of answers to them. A direct analogy is drawn with the Unified State Exam. In this case, you can give both short and detailed answers. Our website website will help you prepare well and realistically assess your chances. Besides, GIA and OGE tests online with answer checking help you decide on your further choice of a specialized high school class. You yourself can easily assess your knowledge in the chosen subject. To do this, our project offers you various tests in a number of disciplines. Our website dedicated to preparation for passing the State Examination Test 2019, grade 9 online, will fully help you prepare for the first serious and responsible test in life.

All materials on our site are presented in a simple, easy-to-understand form. Whether you are an excellent student in your class or an ordinary average student, everything is now in your hands. It would be a good idea for you to visit ours. Here you will find answers to all your questions. Be prepared for the difficult test of the OGE, GIA and the result will exceed all your expectations.

• a scale for recalculating the primary score for completing the 2020 examination paper into a mark on a five-point scale;
• a scale for recalculating the primary score for completing the 2019 examination paper into a mark on a five-point scale;
• scale for recalculating the primary score for completing the 2018 examination paper into a mark on a five-point scale;
• a scale for recalculating the primary score for completing the 2017 examination paper into a mark on a five-point scale;
• a scale for recalculating the primary score for completing the 2016 examination paper into a mark on a five-point scale;
• a scale for recalculating the primary score for completing the 2015 examination paper into a mark on a five-point scale;
• a scale for recalculating the primary score for completing the 2014 examination paper into a mark on a five-point scale;
• scale for recalculating the primary score for completing the 2013 examination paper into a mark on a five-point scale.

Changes in demo versions of the OGE in biology

Demonstration versions of the OGE in biology 2009-2014 consisted of 3 parts: tasks with a choice of answers, tasks with a short answer, tasks with a detailed answer.

In 2013 in part 2 (B) was added a practice-oriented task for correlating, according to a given algorithm, the morphological characteristics of an organism or its individual organs with the proposed models.

In 2014 in demonstration OGE option in biology the following were introduced changes:

• in part 1(A) it was on 2 abbreviated number of tasks,
• in part 2 (B) there was added a new task with choosing three correct answers out of six;
• in part 3(C) there was new task included on the application of biological knowledge in a practical situation;
• the total number of tasks has not changed, but maximum primary score for completing the examination work increased from 43 to 46.

In 2015 in In the demo version of the OGE in biology, the structure of the version has changed:

• The option began to consist two-piece.
• Numbering tasks became through throughout the entire version without letter designations A, B, C.
• The form for recording the answer in tasks with a choice of answers has been changed: the answer now needs to be written down number with the number of the correct answer(not circled).

IN demo versions of the OGE 2016 - 2019 in biology compared with demo version 2015 there were no changes.

IN demo version of the 2020 OGE in biology Compared to the 2019 demo version, the following occurred: changes:

• Was the number of tasks has been reduced from 32 to 30.
• Was reduced maximum primary score from 46 to 45.
• In part 1 there were new models of tasks 1 and 20 included.
• In part 2 there was added new task 27, A tasks 31 and 32 reworked into new task 30.

The demo version of the OGE in Biology is intended to enable any exam participant and the general public to get an idea of ​​the structure of the future examination paper, the number and form of tasks, as well as their level of complexity.

The given criteria for assessing the completion of tasks with a detailed answer, included in this option, will allow you to get an idea of ​​the requirements for the completeness and correctness of recording a detailed answer.

Demo version of the OGE in biology 2018 (grade 9)

Changes in KIM OGE 2018 in biology compared to 2017 none

Total tasks - 32; of which by type of task: with a short answer recorded – 28; with a detailed answer – 4; by level of difficulty: B – 22; P – 7; AT 3.

Maximum score – 46.

The total time to complete the work is 180 minutes.

Since there are no changes, the demo version of the OGE 2017 is relevant for preparation.

Demo version of the OGE in biology 2017

Additional materials and equipment

Scroll additional materials and equipment, the use of which is permitted at the OGE, is approved by order of the Russian Ministry of Education and Science. In the biology exam, you are allowed to use a ruler and a non-programmable calculator.

The examination paper consists of two parts, including 32 tasks.

Part 1 contains 28 short-answer tasks, part 2 contains 4 long-answer tasks.

Answers to tasks 1–22 are written as one number, which corresponds to the number of the correct answer. Write this figure in the answer field in the text of the work, and then transfer it to answer form No. 1.

Answers to tasks 23–28 are written as a sequence of numbers. Write this sequence of numbers in the answer field in the text of the work, and then transfer it to answer form No. 1.

For tasks 29–32 you should give a detailed answer. The tasks are completed on answer form No. 2.

System for assessing the completion of individual tasks and the exam work of the OGE in biology as a whole

For correct completion of each of tasks 1–22, 1 point is awarded, otherwise - 0 points.

For correct completion of each of tasks 23–27, 2 points are awarded.

For answers to tasks 23 and 24, 1 point is given if the answer contains any two numbers presented in the answer standard, and 0 points in all other cases.

If the examinee indicates more characters in the answer than in the correct answer, then for each extra character 1 point is reduced (up to 0 points inclusive). For the answer to tasks 25 and 27, 1 point is given if one mistake is made, and 0 points if two or more mistakes are made.

For the answer to task 26, 1 point is given if the symbol written in any two positions of the answer is not the one presented in the answer standard. If there are more errors, then 0 points are given.

For complete correct completion of task 28, 3 points are awarded; 2 points if at any one position of the answer the symbol written is not the one presented in the answer standard; 1 point is given if any two positions of the answer contain characters that are not those presented in the answer standard, and 0 points in all other cases.

Tasks 29–32 are graded depending on the completeness and correctness of the answer.

The maximum initial score for completing all work is 46

Block 3. System, diversity and evolution of living nature

Animal Kingdom

TYPE CHORDATES. SUPERCLASS FISH

Fish are the largest group of vertebrates. Fish are divided into the class Cartilaginous fish (sharks, rays ) and class Bony fishes (sturgeon, salmon, herring, crucian carp, pike, swordtail and etc.). The main criterion for this division is the substance of which the internal skeleton of fish consists:cartilage or bone.

Animals of this, the most thriving group of vertebrates today, can be found in all corners of our planet - from the North Pole to the South. They are found in brackish waters of seas and oceans, and in fresh waters lakes and rivers; They live in the dark depths of ocean basins and in sun-drenched coral reefs. The number of their forms is countless, and each fish is in amazing harmony with its environment.

Fish - large group vertebrates. The branch of zoology that studies fish is calledichthyology .

general characteristics fish

Fish are vertebrates that live in water (an environment much denser than air). The fish body is remarkably adapted to carry out all vital functions. important functions in water. The body of the fish is usually covered with scales and has a streamlined shape. It consists of three parts:heads, torsos And tail . The main respiratory organ is the gills. Like other vertebrates, fish have a hard skeleton, muscles, skin, digestive, circulatory and nervous systems, respiratory, excretory and reproductive organs.

Fish are cold-blooded animals: their body temperature is close to environment. Therefore, we can say that the rate of metabolic processes in them depends on the temperature of the water.

Today, about 25 thousand species of fish are known.

Habitats and external structure of fish

The habitat of fish is various bodies of water on our planet: oceans, seas, rivers, lakes, ponds. It is very vast: the area occupied by the oceans exceeds 70% of the Earth’s surface, and the deepest depressions go 11 thousand meters deep into the oceans.

The variety of living conditions in water influenced the appearance of fish and contributed to a wide variety of body shapes: the emergence of many adaptations to living conditions, both in structure and in biological characteristics.

General plan of the external structure of fish

On the head of the fish there are eyes, nostrils, a mouth with lips, and gill covers. The head smoothly transitions into the body. The body continues from the gill covers to the anal fin. The body of the fish ends with a tail.

The outside of the body is covered with skin. Protects mucus-coated skin of most fishscales .

The locomotion organs of fish arefins . Fins are outgrowths of skin resting on bones.fin rays . The caudal fin is of greatest importance. On the lower sides of the body there are paired fins: pectoral and ventral. They correspond to the fore and hind limbs of terrestrial vertebrates. The position of paired fins varies among different fish. The dorsal fin is located on top of the fish’s body, and the anal fin is located below, closer to the tail. The number of dorsal and anal fins may vary.

On the sides of the body of most fish there is a kind of organ that senses the flow of water. Thislateral line . Thanks to the lateral line, even blinded fish do not bump into obstacles and are able to catch moving prey. The visible part of the lateral line is formed by scales with holes. Through them, water penetrates into a channel stretching along the body, to which the endings of nerve cells approach. The lateral line may be intermittent, continuous, or completely absent.

Functions of fins

Thanks to fins, fish are able to move and maintain balance in the aquatic environment. Deprived of fins, it turns over with its belly up, since the center of gravity is located in the dorsal part.

Unpaired fins (dorsal and anal) provide stability to the body. The caudal fin in the vast majority of fish performs the function of propulsion.

Paired fins (thoracic and abdominal) serve as stabilizers, i.e. provide a balanced position of the body when it is immobile. With their help, the fish maintains its body in the desired position. When moving, they serve as load-bearing planes and steering wheels. The pectoral fins move the fish's body when swimming slowly. The pelvic fins perform mainly a balancing function.

Body Shape

Fish have a streamlined body shape. It reflects the characteristics of the environment and lifestyle. In fish adapted to fast, long-term swimming in the water column (tuna (2), mackerel, herring, cod, salmon ), “torpedo-shaped” body shape. In predators that practice quick throws at short distances (pike, taimen, barracuda, garfish (1), saury ), it is “arrow-shaped”. Some fish adapted to long-term residence on the bottom (ramp (6) , flounder (3) ), have a flat body. U individual species the body has a bizarre shape. For example,sea ​​Horse resembles a corresponding chess piece: its head is located at right angles to the axis of the body.

Coverings of the body

On the outside, the skin of fish is covered with scales - thin translucent plates. The scales overlap each other with their ends, arranged in a tile-like manner. This provides

strong protection of the body and at the same time does not create obstacles to movement. Scales are formed by special skin cells. The size of the scales varies: from microscopic toblackheads up to several centimetersIndian barbel . There is a wide variety of scales: in shape, strength, composition, quantity and some other characteristics.

Lie in the skin pigment cells - chromatophores : when they expand, the pigment grains spread over a larger space and the color of the body becomes bright. If the chromatophores contract, the pigment grains accumulate in the center, leaving most of the cell uncolored, and the body color fades. If pigment grains of all colors are evenly distributed inside the chromatophores, the fish is brightly colored; if pigment grains are collected in the centers of cells, the fish becomes almost colorless and transparent; if only yellow pigment grains are distributed among their chromatophores, the fish changes color to light yellow.

Chromatophores determine the diversity of fish colors, which are especially bright in the tropics. Thus, fish skin performs the function of external protection. It protects the body from mechanical damage, facilitates sliding, determines the color of the fish, and communicates with external environment. The skin contains organs that sense temperature and chemical composition water.

Peculiarities internal structure and fish life

Musculoskeletal system fish consists of a skeleton and muscles. The basis of the skeleton is formed by the skull and spine.Spine consists of individual vertebrae. Each vertebra has a thickened part - the vertebral body, as well as the upper and lower arches. The superior arches together form the canal in which the spinal cord lies. The arches protect him from injury. Long ones stick out from the archesspinous processes . The lower arches in the body part are open. Adjacent to the lateral processes of the vertebraeribs - they are covering internal organs and serve as a support for the trunkmuscles . Particularly powerful muscles are located in fish in the back and tail. In the tail, the lower arches of the vertebrae form a canal through which blood vessels pass.

The skeleton also includes bones and bony raysdoubles And unpaired fins . The skeleton of unpaired fins consists of many elongated bones embedded in the thickness of the muscles. Paired fins have skeletonsbelts and skeletons free limbs . The skeleton of the pectoral girdle is motionlessly attached to the skeleton of the head. The skeleton of the free limb (the fin itself) includes many small and elongated bones. There is a single bone in the abdominal girdle. The skeleton of the free pelvic fin consists of many long bones.

In the skeleton of the head a smallscull, or skull . The bones of the skull protect the brain. The main part of the skeleton of the head consists of the upper and mandibles, bones of the eye sockets and gill apparatus. Large ones are clearly visible in the gill apparatus.gill covers . If you lift them up you can seegill arches – they are paired: left and right. Gills are located on the gill arches. There are few muscles in the head; they are mainly located in the area of ​​the gill covers, jaws and on the back of the head.

Muscles are attached to the bones of the skeleton, which provide movement through their work. The main muscles are located evenly in the dorsal part of the fish's body; The muscles that move the tail are especially well developed.

The musculoskeletal system performs different functions in the body. It serves as a support, allows movement, and protects from shocks and collisions. The skeleton protects the internal organs. Bony fin rays are a weapon of defense against predators and rivals.

Digestive system begins with a large mouth located at the end of the head and armed with jaws. There is an extensive oral cavity. Are there small or largeteeth . Behind the oral cavity is the pharyngeal cavity. It shows gill slits separated by interbranchial septa. They have gills on them. They are covered by gill covers from the outside. Next comes the esophagus and a voluminous stomach. Behind the stomach is the intestine. In the stomach and intestines, food is digested under the influence of digestive juices: in the stomach there is gastric juice, in the intestine there are juices secreted by the glands of the intestinal walls and pancreas, as well as bile coming from the gallbladder and liver. In the intestines, digested food and water are absorbed into the blood. Undigested residues are thrown out through the anus.

The digestive system provides the fish with the necessary nutrients.

The swim bladder is a special organ found only in bony fish. It is located in the body cavity under the spine. During embryonic development arises as a dorsal outgrowth of the intestinal tube. In order to fill the bladder with air, the newborn fry floats to the surface of the water and swallows air into the esophagus. Later, the connection between the swim bladder and the esophagus is interrupted.

Interestingly, with the help of a swim bladder, some fish are able to amplify the sounds they make. Some species of fish do not have this organ (for example, those living on the bottom or those characterized by rapid vertical movements).

The swim bladder prevents the fish from drowning under its own weight. It consists of one or two chambers, filled with a mixture of gases similar in composition to air. The volume of gases in the swim bladder can change when they are released and absorbed through the blood vessels of the bladder walls or when air is swallowed. This changes the body volume of the fish and its specific gravity. Thanks to the swim bladder, the body mass of the fish comes into balance with the buoyant force acting on the fish at a certain depth.

Respiratory system located in the pharynx area.

The skeletal support of the gill apparatus is provided by four pairs of vertical gill arches, to which the gill plates are attached. They consist of fringedgill filaments , inside which there are thin-walled blood vessels branching into capillaries. Gas exchange occurs through the walls of capillaries: absorption of oxygen from water and release of carbon dioxide. Water moves between the gill filaments due to the contraction of the pharyngeal muscles and the movement of the gill covers. The gill arches have gill rakers. They protect the soft, delicate gills from becoming clogged with food particles.

Circulatory system fish schematically represents vicious circle consisting of vessels. Its main organ is the heart. Ittwo-chamber: comprises atria And ventricle . The work of the heart ensures blood circulation. Moving through the vessels, blood carries out gas exchange, transport of nutrients and other substances in the body.

The circulatory system of fish includesone circle of blood circulation . From the heart, blood flows to the gills, where it is enriched with oxygen. Oxygenated blood is calledarterial . It spreads throughout the body, gives oxygen to cells, is saturated with carbon dioxide, i.e. it becomesvenous , and returns to the heart. In all vertebrates, the vessels that extend from the heart arearteries . The vessels that lead to the heart areveins .

Excretory organs filter water and metabolic waste products from the blood and remove them from the body. Excretory organs are presented in pairskidneys located along the spine,and ureters . Some fish have bladder.

Removing excess fluid, salts from branched blood vessels, harmful products exchange occurs in the kidneys. Urine flows through the ureters into the bladder and is expelled from it. The urinary canal opens outward through an opening located behind the anus. Through these organs, excess salts, water and metabolic products harmful to the body are removed from the fish’s body.

Metabolism – set chemical processes occurring in a living organism . Metabolism is based on two phenomena: the construction and breakdown of organic substances. Complex organic matter, entering the body with food during the digestion process are transformed into less complex ones. They are absorbed into the blood and carried to the cells of the body, where they form the proteins, fats and carbohydrates necessary for the body. This uses energy that is released during breathing. At the same time, many substances in cells break down into water, carbon dioxide and urea. Thus,metabolism consists of processes of construction and breakdown of substances .

The metabolic rate of fish depends on body temperature. Fish are animals with variable body temperatures - cold-blooded. The body temperature of fish is close to the ambient temperature and does not exceed it by more than 0.5–1.0 degrees (although in tuna fish the difference can be up to 10 degrees).

Nervous system is responsible for the coherence of the work of all systems and organs, the implementation of the body’s reactions to environmental changes. Like all vertebrates, in fish it consists of the brain, spinal cord (central nervous system) and nerves extending from them (peripheral nervous system).Brain consists of five departments:front , including the optic lobes,middle, intermediate, cerebellum And oblong brain. All active pelagic fish have large optic lobes and cerebellum because they require good vision and fine coordination. The medulla oblongata passes into the spinal cord, which ends in the caudal spine.

with the participation nervous system the body responds to various irritations. This reaction is calledreflex . The behavior of fish showsunconditional And conditional reflexes. Unconditioned reflexes are otherwise called innate. In all animals belonging to the same species, unconditioned reflexes manifest themselves in the same way. Conditioned reflexes are developed during the life of each fish. For example, by tapping on the glass of the aquarium every time during feeding, you can ensure that the fish begin to gather near the feeder only when knocking.

Sense organs fish are well developed. The eyes are adapted to clearly recognize objects at close range and distinguish colors. Through the inner ear, an organ located inside the skull, fish perceive sounds. Odors are detected through the nostrils. IN oral cavity, in the skin of the antennae and lips there are taste organs that determine sweet, sour, salty.

Perceives the direction and strength of water flowlateral line . It is formed by a channel passing inside the body, which communicates with aquatic environment through holes in the scales. Sensitive cells in the lateral line respond to changes in water pressure and transmit signals to the brain.

Features of fish reproduction and development

Reproductive organs . Almost all fish dioecious . For reproduction, special paired organs are used: in males -testes (milt), vas deferens, in females -ovaries , oviducts. Male germ cells - sperm - develop in the testes, and female germ cells - eggs (eggs) - develop in the ovaries. There is a special genital opening for their removal. In some fish species, males and females differ in color and body shape. Biologists call this phenomenon sexual dimorphism.

Sexual dimorphism is manifested in the external differences of individuals of the opposite sex (based on these differences, they recognize and choose each other). A striking example of sexual dimorphism is the extremely peculiar appearance of males and females of some deep-sea fish -anglerfish .

Small males, only a few centimeters in size, are attached to the body of much larger females. Or rather, they grow, because in this case their circulatory system becomes an appendage of the female’s circulatory system. From this moment on, males become incapable of independent existence. They are needed only for the production of offspring.

Reproduction and development of fish. When the reproductive cells mature, the reproductive instinct appears in fish. Fish reproduction is calledspawning . Readiness for spawning is signaled by the behavior of the fish and its nuptial coloration. Some fish spawnmigration , moving to places more suitable for the development of their future offspring.Salmon, eels and a number of other fish overcome enormous distances.

Spawning females lay eggs, which are fertilized by the males. Fish lay eggs on accumulations of algae, lumps of mucus, foam bubbles at the surface of the water, in holes at the bottom, etc. External fertilization - occurs in the environment.

When sex cells fuse, an egg is formed, which matures in water. An embryo develops inside the egg. A mature fish embryo is freed from its shell, enters the water and from that moment is called a larva. Over time, the larva begins to independently feed on microscopic algae, ciliates, and then small crustaceans. If it survives, it becomes similar to an adult fish, it is calledlittle boy .

In many species of fish, enormous fertility is an adaptation to survival. So femaleriver perch lays 200–300 thousand eggs, femalecarp 400–600 thousand eggs, and the femalecod up to 10 million. There are fish that do not lay a large number of caviar. However, these fish take care of their offspring. For example,three-spined stickleback lays only 60–70 eggs. Caring for offspring takes place in a special wayseahorses, pipefish, tilapia . There are also viviparous fish species. During a live birth, the number of cubs born is reduced to tens and units. Some sharks and rays lay eggs with a well-developed large embryo. These eggs have special devices for attaching to plants.

Growing up, the fry move on to “adult” life and enter the feeding period. Having reached sexual maturity, fish begin to reproduce.

The process of reproduction is very significant for the survival of the species. As a result of evolution, fish have developed suchcomplex behaviors , like spawning migrations (salmon, sturgeon, freshwater eel ), caring for offspring (three-spined stickleback, seahorse etc.), mating “dances”. All of these are adaptations of species to living conditions and survival next to other species of organisms.

Migrations. As we found out, fish go through the following stages during their life cycle: egg, larva, fry, feeding, mature individual. In some fish, for examplesalmon , migrations are necessarily present in the life cycle. The first three stages (they take from 2 to 5 years of life) are spent by salmon in rivers. Then the time comes for the first migration, and the young salmon slide down the rivers into the sea. Here, moving and feeding over a wide area, salmon quickly develop (feed) and reach sexual maturity.

After this, salmon begin their second (spawning) migration to their native rivers, where they find their way by the smell of the water. The fish rise to the upper reaches of the river and spawn. This ends the reproduction cycle. Weakened parents drift downstream. Many die, but many survive for subsequent migrations and spawning.Far Eastern salmon (pink salmon) after spawning it dies. Fish that migrate from rivers to seas or from seas to rivers are calledpassable . These include many species of herring, salmon, and sturgeon. The listed fish, like salmon, breed in rivers and feed in the sea. Migratory fish need freedom of movement along rivers. Therefore, their survival requires the creation of special devices that help them bypass hydroelectric dams. Some species of fish have special adaptations in the structure of their bodies that allow them to overcome various barriers and obstacles on the way to spawning sites.

Eel migrations. Lives in the rivers of EuropeEuropean river eel . Eels can reach 2 m in length and 6 kg in weight. The river eel is a migratory fish. In the river eel, the juvenile stage, spawning migration and spawning take place in the sea, and growth and feeding take place in fresh water. Eel can long time be in their main habitats - quiet river backwaters. At the onset of puberty, the eel changes its appearance (the diameter of the eyes increases, the back turns from olive green to black, and the belly turns silvery-white), rolls into the sea and stops feeding. It is known that spawning migrations of eels in the Baltic Sea pass through coastal waters, and, starting from North Sea, their trace has not been studied. In the end, the eel ends up at its spawning site: off the coast of America in the Sargasso Sea. Having spawned at a depth of 300–400 m, the eel dies. The larvae emerging from the eggs (they are calledleptocephali ) are so different from their parents that they were at one time considered a different species of fish.

These eel larvae, having appeared in the Sargasso Sea, float to the upper layers of the water, are picked up by currents arising in the western part of the North Atlantic, and drift for 2.5–3 years to the shores of Europe. During this migration, the eel's body undergoes quite complex transformations. Transparent three-year-old eel fry (glass eels) appear in schools off the coast of Europe. Next, male eels fatten in brackish waters. And females enter rivers, migrate against the current, settle in various bodies of water and live in fresh water for at least several years. They feed on small fish, caviar, and frogs. At the onset of puberty, it is time to go to their native places.

Not all questions related to the long migrations of European eels have been clarified. In addition to river eels, such migrations are characteristic of some species of gobies and tropical species of catfish.

Caring for offspring in seahorses. An exemplary father among fish issea ​​Horse . Widespread in the seas and oceans, skates have a hard body covered with plates of the exoskeleton. There is a pocket on the male’s belly that opens outwards with only a small hole.

For the entire breeding season, pipits form a permanent pair, which occupies a certain area in the sea thickets. If any stranger encroaches on this territory, the male will drive him away. During spawning, the female places eggs inside the male's brood pouch, which develop there. The tissues of the brood pouch contain a large number of small blood vessels through which the eggs are supplied with oxygen. Egg laying usually occurs several times, so the small pipits in the male’s pouch can be of different ages, and then the older generation leaves the paternal pouch at intervals of several days.

Sometimes the father’s care does not end there, and fully formed young skates that have already left the bag, in case of danger, can briefly return to the protection of their father.

Viviparity. Some species of fish do not lay eggs, but give birth to young that develop inside the mother's body. In this case, the development of the larvae occurs directly in the oviducts of the female due to nutrients, available in the egg. Viviparous fish species include not only sea giants (sharks, rays), but also very small fish (aquariumguppies, swordtails ).

The importance of fish in nature and human life. Fish protection and breeding

Role in nature. About 70% of the Earth's surface is covered with water, or more precisely, with aquatic biogeocenoses: stable communities of living organisms that have developed in the process historical development Earth. Each species, as an inhabitant of one or another biogeocenosis, has developed characteristic adaptations to life in communities. Each species plays its own unique role here.

In aquatic biogeocenoses, fish enter into various relationships with other organisms. Considering, for example, the food chains of aquatic biogeocenoses, one can be convinced that fish eat a large number of animal and plant organisms. But they themselves, in turn, serve as food for many other organisms. Very interesting relationships in which different types animals are related to each other for mutual benefit (symbiosis). How does this happen inamphiprion (clown fish) and sea anemones.

hydroid polyps that help them camouflage themselves on the bottom. Hydroid polyps, in turn, find a means of transportation in fish.

The importance of fish in human life.Fishing - one of the most ancient forms economic activity of people. Fish for humans is a source of very valuable nutrients, mainly animal proteins and fats, and these products are more easily absorbed by the human body than plant foods.

Fish (especially bony fish) are of great practical importance for humans. In addition to food products, fish serve as raw materials for obtaining medicine ( fish fat etc.), feed for livestock and poultry ( feed meal), fertilizers for fields, technical fat, glue, leather and other materials used in the food and light industries. There are countries where the well-being of the population directly depends on fishing.

Up to 90% of the mass of fish is caught in the seas and oceans. The main objects of marine fishing arecod, haddock, navaga, pollock, herring, herring, sardine, sea bass, flounder, saury, mackerel, tuna . In Russian rivers they catch sturgeon, salmon,ram, roach, pike perch and other fish. Meat, fat, and caviar are used as food.

Millions of people are engaged in fishing, breeding and processing fish, building ships and making fishing equipment.

Hundreds of thousands of people enjoy fishing and spearfishing, for whom this wonderful sport gives them health and relaxation. Even more hobbyists are creating a colorful, quiet world in the glass containers of their aquariums.

Fish protection. Marine fisheries are currently experiencing great difficulties. They are associated with pollution water resources(due to oil tanker accidents; pollution caused by mining; coastal runoff discharges). In addition, using modern powerful tools fishing, you can completely catch all the fish and thereby not only stop further fishing, but also cause irreparable harm to nature. To prevent this from happening, special measures are taken to protect and reproduce fish.

Ecology states: the most unstable factors in the existence of fish today are the purity of water, air conditions, and the preservation of species habitats. And it offers basic principles for environmentally friendly activities near and in water bodies.

The basis for the stability of biogeocenoses is the diversity of species. In order for aquatic biocenoses to always exist, it is necessary by all means to preserve fish species, and first of all, those that are in danger of extinction (due to deteriorating environmental conditions, overfishing or other factors).

World organizations Laws on the protection and use of the planet's fauna are adopted. In particular, all fishing enterprises, as well as amateur fishermen, are required to strictly observe the established fishing rules. The laws define fishing methods and seasons. The diameter of the net cells should be such as not to impede the emergence of juveniles from them. On the rivers and ponds of Russia, the use of nets is strictly prohibited, as is the killing of fish with explosions (after all, this would kill almost the entire population of a given section of the reservoir). Much attention should be paid to the construction of treatment facilities that prevent water contaminated by wastewater from factories and factories from entering rivers, lakes and seas.

Valuable fish. Of particular scientific and biological value are rare fish world and Russia. Among them, we note species that are found only in a given habitat (they are calledendemic ). Endemic to Russia is, for example,Kaluga , swimming from the sea to the Amur. Many endemic fish species live in Lake Baikal. These species must be protected as a special natural value.

From an industrial point of view, sturgeon and salmon fish. Their meat and caviar are tasty and nutritious!

The characteristics of individual fish species are valued and used by humans. So, exported from AmericaGambusia spread to control mosquitoes. After all, she feeds on their larvae.

Variety of fish

Studying the diversity of fish, ichthyologists divide them into different groups. Thus, depending on their relationship to the environment, all fish are divided into marine, freshwater and anadromous.

By sea species are the majoritysharks, rays , many herring and other fish.

TO freshwater include, for example, carp-like:roach, dace, asp, tench, barbel, bream, bleak, sabrefish, carp, crucian carp, cupid . In fresh waters, an important factor determining the distribution of fish is water flow.Bream lives only in running water. Butcrucian carp, rotan can live in small ponds and swampy lakes.

To those who live both in fresh water and in sea ​​water(i.e.passable ) include sturgeons, salmonids,freshwater eel etc. Migratory fish are usually able to adapt to strong fluctuations in water salinity. In addition, during their life cycle they need to prepare the body for large energy expenditures associated, for example, with overcoming currents.

In addition, among fish there arepelagic , i.e. living in the water column (herring, horse mackerel, cod, tuna ), And bottom , i.e. living at the bottom (flounder, catfish ).

There are peaceful fish among themherbivores species (eg silver carp ) and very aggressivepredators (pike, perch, catfish ).

Class Cartilaginous fish

Fishes with a cartilaginous, non-ossifying skeleton are classified asclass Cartilaginous fish . These fish do not have gill covers. On each side of the body, 5–7 pairs of gill slits separated from each other open freely. Among cartilaginous fish there are three orders:Sharks, Rays, Chimaeras .

Shark Squad. There are more than 250 species of sharks. Their sizes are different. For example,midget shark , living in the Gulf of Mexico, does not exceed 20 cm in length and weighs no more than 500 g. Awhale shark has a length of 18–20 m and a mass of about 10 tons. The skin of sharks is rough, covered with scales with numerous teeth. In external structure sharks reflect all the adaptations to life in the water column: a torpedo-shaped body shape, a sharp nose, a dark body color on top and light below.

Paired pectoral and pelvic fins provide the shark with up and down movement. The upper lobe of the caudal fin is usually longer than the lower one. Vision is black and white. Sharks have a well-developed sense of smell, with which they find prey. They live mainly in the seas. Most are active predators. They hunt fish, shrimp, and aquatic mammals. Whale shark feeds on plankton.Herring sharks - viviparous fish. They are found in the Atlantic and Pacific Oceans in temperate and subtropical waters. Most dangerous to humansbrindle And blunt-nosed sharks, hammerhead shark, mako And large white . Sharks are a commercial target. Shark liver, which occupies 20–30% of body weight, is considered a valuable product.

Squad Stingray. About 350 species of stingrays are known. These are large fish with a flat, dorsoventrally flattened, diamond-shaped body. On the sides it is formed by extended pectoral fins. When moving, the fins move in waves.

The sizes of the slopes are different. The smallest stingray -dipteran from the Yellow Sea - has a width of 10–15 cm. The most major representative squad -manta ray – the fin span reaches 8 m and has a mass of about 2.5 tons.

On the ventral side of the stingray's body, a transverse mouth opens with a powerful grater of teeth, as well as five pairs of gill slits. Many have spines (skin teeth) on their scales. They feed on bottom animals: mollusks, worms, crabs, fish.

The tail of the stingrays is extended into a whip. At the end of the tail, stingrays have a spike with a poisonous gland.

Some tropical species of stingrays have electrical organs. Electrical discharges of up to 300 volts are produced, probably for protection purposes. Electrical processes in muscle tissue stingrays have not yet been properly explained. Stingrays are commercially available. Some are dangerous to humans.

The Chimera squad is a representative of the Whole-headed or Solid-skulled subclass. In chimeras, the jaws are completely fused with the skull; in this they strongly resemble bony fish. The gill slits are covered by a fold of skin. There is no cloaca, the anal and urogenital openings are separated from each other. The naked body is up to 1.5 m long, gradually becoming thinner, turning into a long tail.

It is believed that chimeras originated from ancient sharks and are a side branch of evolution. Whole-headed animals have been known since the Upper Devonian; currently only the order of chimeras exists. Of more than a dozen of its families, only 3 have survived to this day; about 30 species living from the shelf to the great depths of the World Ocean. Chimeras feed on marine invertebrates and fish. They have practically no commercial significance.

Class Bony fish

Bony fish are a class of aquatic vertebrates. All structural features of fish are determined by the environment in which they live. Long-term adaptation to life in water has not left a single unnecessary detail that interferes with movement.

Body sizes range from 0.7 - 0.9 cm (Philippine goby ) up to 17 m ( herring king ); blue marlin weighs up to 900 kg. The body shape is usually elongated and streamlined, although some bony fish are flattened dorsoventrally or laterally, or vice versa have a spherical shape. Forward movement in water is carried out due to wave-like movements of the body. Some fish “help” themselves with their caudal fin. Paired lateral, as well as dorsal and anal fins serve as stabilizer rudders. In some fish, individual fins have been transformed into suckers or copulatory organs.

On the outside, the body of bony fish is covered with scales: placoid (teeth laid “in parquet”),ganoid (rhombic plates with a spike),cycloid (thin plates with a smooth edge) orctenoid (plates with spines), periodically changing as the animal grows. The growth rings on it allow one to judge the age of the fish.

Many fish have well-developed mucous glands on their skin; their secretions reduce the force of resistance to the oncoming flow of water. Some deep-sea fish develop luminous organs on their skin, which serve to identify their species, consolidate the school, lure prey, and scare away predators. The most complex of these organs are similar to a spotlight: they have luminous elements (such as phosphorescent bacteria), a mirror reflector, a diaphragm or lens, and an insulating black or red coating.

The coloring of fish is very diverse. Typically, fish have a bluish or greenish back (to match the color of the water) and silvery sides and belly (hardly visible against the background of the light “sky”). Many fish are covered with stripes and spots for camouflage. On the contrary, the inhabitants of coral reefs amaze with a riot of colors.

Variety of bony fish

Most species of fish are classified as bony fish. They are divided into osteochondral, lungfish, lobe-finned and teleost.

Osteochondral, or sturgeon, fish includeBeluga, sterlet, Russian sturgeon . They have an osteochondral skeleton with a well-developed notochord, gill covers and a swim bladder. Along the body of sturgeon there are 5 rows of bone plates, between which there are small bone plates. The head, like a shark's, has an elongated snout. Near the mouth, located on the underside of the head, there are antennae. The caudal fin is unequally lobed.

Sturgeons: beluga (1), Siberian sturgeon (2), sterlet (3), stellate sturgeon (4), shovelnose (5), paddlefish (6).

Sturgeon are migratory fish northern hemisphere. They live up to 50–100 years or more. These fish are widely known due to their special delicious meat and black caviar. A typical representative of sturgeon -Russian sturgeon , a common inhabitant of the Volga-Caspian and Black Sea basins. Spends most of its time at sea, spawning in rivers. The sturgeon feeds mainly annelids and shellfish. For the winter it lies in deep holes, most often in the estuaries of rivers. Currently, the sturgeon population is small.

Lungfishes are a small (only 6 species) ancient group of fish. Among themAustralian horntooth, African And South American lepidoptera . In lungfishes, the notochord is preserved throughout their lives and the vertebral bodies do not develop, which indicates their antiquity. Unpaired fins have a feathery structure characteristic of the subclass. Upper jaw fused to the skull. Along with gills, these fish have lungs that develop from the swim bladder. Some lungfish, rising to the surface, can swallow atmospheric air. The elongated body can reach a length of 2 m. These fish can wait out long droughts by burying themselves in the mud. The structure of the heart has also changed: the atrium is divided by an incomplete septum into left and right halves. The right half receives blood from the gills, and the left half receives blood from the lungs.

Dipnoi: Horntooth (barramunda) (7), lepidosiren (8), large protopter (mamba) (9).

Lungfish – freshwater fish, living in stagnant or drying up reservoirs.

Australian horntooth (more than 1 m long) lives in rivers heavily overgrown with plants. In the summer, when reservoirs become shallow, breaking up into a chain of pits - barrels with rotting water, he completely switches to breathing atmospheric air. Having put its snout above the water, it forcefully throws out the “exhausted” air and at the same time makes a groaning-grunting sound that spreads far throughout the surrounding area. The cattail feeds on mollusks, crustaceans, worms, and insect larvae.

Other representatives of lungfishes -African scalefish (up to 2 m long) and South American lepidoptera (up to 1 m long) when water bodies dry up, they bury themselves in silt and hibernate.

Lobe-finned fish are an ancient group of fish. Until the first half of the 20th century. they were considered an extinct branch of vertebrates that were once widespread in both fresh water and seas. Lozenge fins are close to lungfishes. Their skeleton was mainly cartilaginous. The notochord was absent in adult fish. The fins of lobefins were similar to the fins of a cattail, the swim bladder turned into a paired lung, and the nostrils communicated with the oropharynx. Currently, one modern representative is known -coelacanth , a descendant of marine lobefins.

Coelacanth - large fish (up to 180 cm long). Its body is covered with massive scales, and its fins (especially paired ones) look like fleshy blades. Coelacanths live at the bottom, at a depth of up to 400 m (possibly deeper), in the southwestern part Indian Ocean. They feed on fish.

Teleosts are the most numerous group of modern fish (about 96% of all species). Their skeleton is ossified, the notochord develops only in the embryo, and the scales are bony. A swim bladder is common for them. Bony fish include such valuable commercial species astuna, halibut, salmon, herring, pike and others. Common for our riverscrucian carp And bream - also bony fish. These fish live in almost all bodies of water on Earth.

Herring: Atlantic herring (10), Japanese anchovy (11), European sprat (12), sardinella (13).

This group includes fishherring orders (herrings, sardines, anchovies , two types of which are called anchovy),salmonids (noble salmon , or salmon, chum salmon, pink salmon, chinook salmon, sockeye salmon, whitefish, grayling, smelt ), carp-like (chub, roach, bream, ide, dace, asp, carp, crucian carp ), catfish (som ), codlike (cod, navaga, haddock, blue whiting, pollock, burbot ), flounder (flounder, halibut ). There are more than 40 units in total.

Very soon every ninth grade will take exams. They influence not only the matriculation certificate, but also whether the student enters tenth grade or college. Biology tests for the OGE are simply necessary for future doctors who plan to obtain a junior medical degree. It’s not for nothing that most schoolchildren consider biology the most difficult school subject. There are many anatomical terms as well as chemical and biological bases.

Features of the biology exam

This exam consists of two parts. The first of them contains twenty-eight tasks, of which 22 are at the basic level of difficulty. Answers to the OGE in biology in tests in this part must be in the form of a single digit, which corresponds to the number of the correct statement.

Another 6 tasks are of an increased level of difficulty. Among two of them, you need to choose and write down three correct answers out of six.

After this stage, they proceed to the most difficult stage, namely the second part. It contains four tasks for which you need to give not just one letter, but a detailed answer. The OGE in biology will be checked by experts who act according to the main assessment criteria.

How are assignments graded?

There is a special table that can be used to convert the number of points scored into a five-point system:

• from 13 to 25 are translated into “3”;
• from 26 to 36 means “4”;
• over 37 – “5”.

Converting grades to points

Point conversion scale

For the first twenty-two tasks, each correct answer is worth one point. If it is completely incorrect, the result will be "0". If tasks from 23 to 27 are completed correctly, “2” points are given for each correct choice.

Task 28 can even be graded “3”. For the next four questions, the score will depend on how complete the answer is and how correctly it is done.

The maximum number of points that can be scored for the OGE tests in biology is “46”. Three hours are given to complete this work.

Where is the best place to prepare?

The well-known portal “Dunno” will allow you to go through biology buildings online.

Dunno website

Also here you can download tasks in PDF format and print them to try to cope with the OGE with a pen. This will help you lose all nerves and feel confident during the exam itself.

Download tasks on the Dunno website

The Yandex OGE website has a huge number of tasks and options that will need to be solved in the same period of time as the real exam.

Yandex OGE

This will help you practice sensing and planning time.

Here students also have the opportunity to download tests.

Download biology tests