Level C questions in biology. Consumers and food chains. Why Food Should Be Chewed Thoroughly
Tasks of the C1-C4 part
1. What environmental factors contribute to the regulation of the number of wolves in the ecosystem?
Answer:
1) anthropogenic: deforestation, overshooting;
2) biotic: lack of food, competition, spread of diseases.
2. Determine the type and phase of cell division shown in the figure. What processes take place in this phase?
Answer:
1) the figure shows the metaphase of mitosis;
2) spindle fibers are attached to the centromeres of chromosomes;
3) in this phase, two-chromatid chromosomes line up in the plane of the equator.
3. Why does plowing the soil improve the living conditions of cultivated plants?
Answer:
1) contributes to the destruction of weeds and weakens competition with cultivated plants;
2) contributes to the supply of plants with water and minerals;
3) increases the supply of oxygen to the roots.
4. How is a natural ecosystem different from an agroecosystem?
Answer:
1) great biodiversity and diversity of food relationships and food chains;
2) a balanced circulation of substances;
3) long periods of existence.
5. Expand the mechanisms that ensure the constancy of the number and shape of chromosomes in all cells of organisms from generation to generation?
Answer:
1) due to meiosis, gametes with a haploid set of chromosomes are formed;
2) during fertilization in the zygote, the diploid set of chromosomes is restored, which ensures the constancy of the chromosome set;
3) the growth of the organism occurs due to mitosis, which ensures the constancy of the number of chromosomes in somatic cells.
6. What is the role of bacteria in the cycle of matter?
Answer:
1) heterotrophic bacteria - decomposers decompose organic substances into minerals that are absorbed by plants;
2) autotrophic bacteria (photo, chemotrophs) - producers synthesize organic substances from inorganic ones, ensuring the circulation of oxygen, carbon, nitrogen, etc.
7. What are the characteristics of mossy plants?
Answer:
2) mosses reproduce both sexually and asexually with alternating generations: sexual (gametophyte) and asexual (sporophyte);
3) an adult moss plant is a sexual generation (gametophyte) and a box with spores is asexual (sporophyte);
4) fertilization occurs in the presence of water.
8. Squirrels, as a rule, live in a coniferous forest and feed mainly on spruce seeds. What biotic factors can lead to a reduction in the squirrel population?
9. It is known that the Golgi apparatus is especially well developed in the glandular cells of the pancreas. Explain why.
Answer:
1) in the cells of the pancreas, enzymes are synthesized that accumulate in the cavities of the Golgi apparatus;
2) in the Golgi apparatus, enzymes are packed in the form of bubbles;
3) from the Golgi apparatus, enzymes are carried into the pancreatic duct.
10. Ribosomes from different cells, the entire set of amino acids and the same molecules of mRNA and tRNA were placed in a test tube, and all the conditions for protein synthesis were created. Why will one type of protein be synthesized on different ribosomes in a test tube?
Answer:
1) the primary structure of a protein is determined by the sequence of amino acids;
2) templates for protein synthesis are the same mRNA molecules, in which the same primary protein structure is encoded.
11. What features of the structure are characteristic of representatives of the Chordata type?
Answer:
1) internal axial skeleton;
2) the nervous system in the form of a tube on the dorsal side of the body;
3) gaps in the digestive tube.
12. Clover grows in a meadow, pollinated by bumblebees. What biotic factors can lead to a decline in the clover population?
Answer:
1) a decrease in the number of bumblebees;
2) an increase in the number of herbivorous animals;
3) reproduction of plants of competitors (cereals, etc.).
13. The total mass of mitochondria in relation to the mass of cells of various organs of the rat is: in the pancreas - 7.9%, in the liver - 18.4%, in the heart - 35.8%. Why do the cells of these organs have a different content of mitochondria?
Answer:
1) mitochondria are the energy stations of the cell, ATP molecules are synthesized and accumulated in them;
2) for the intensive work of the heart muscle, a lot of energy is needed, therefore the content of mitochondria in its cells is the highest;
3) in the liver, the number of mitochondria is higher compared to the pancreas, since it has a more intensive metabolism.
14. Explain why beef that has not passed sanitary control is dangerous to eat undercooked or lightly fried.
Answer:
1) in beef meat there may be finns of bovine tapeworm;
2) in the digestive canal, an adult worm develops from the Finn, and the person becomes the final owner.
15. Name the plant cell organoid shown in the figure, its structures, indicated by numbers 1-3, and their functions.
Answer:
1) the depicted organoid is a chloroplast;
2) 1 - grana thylakoids, participate in photosynthesis;
3) 2 - DNA, 3 - ribosomes, are involved in the synthesis of their own chloroplast proteins.
16. Why bacteria cannot be classified as eukaryotes?
Answer:
1) in their cells, the nuclear substance is represented by one circular DNA molecule and is not separated from the cytoplasm;
2) do not have mitochondria, Golgi complex, EPS;
3) do not have specialized germ cells, there are no meiosis and fertilization.
17. What changes in biotic factors can lead to an increase in the population of the naked slug that lives in the forest and feeds mainly on plants?
18. In the leaves of plants, the process of photosynthesis proceeds intensively. Does it occur in mature and unripe fruits? Explain the answer.
Answer:
1) photosynthesis occurs in immature fruits (while they are green), since they contain chloroplasts;
2) as they mature, chloroplasts turn into chromoplasts, in which photosynthesis does not occur.
19. What stages of gametogenesis are indicated in the figure by the letters A, B and C? What set of chromosomes do cells have at each of these stages? To the development of what specialized cells does this process lead?
Answer:
1) A - stage (zone) of reproduction (division), diploid cells;
2) B - growth stage (zone), diploid cell;
3) B - stage (zone) of maturation, haploid cells, spermatozoa develop.
20. How do bacterial cells differ in structure from the cells of organisms of other kingdoms of wildlife? List at least three differences.
Answer:
1) there is no formed core, nuclear membrane;
2) a number of organelles are absent: mitochondria, ER, Golgi complex, etc.;
3) have one ring chromosome.
21. Why are plants (producers) considered the initial link in the circulation of substances and the transformation of energy in an ecosystem?
Answer:
1) create organic substances from inorganic;
2) accumulate solar energy;
3) provide organic matter and energy to the organisms of other parts of the ecosystem.
22. What processes ensure the movement of water and minerals through the plant?
Answer:
1) from the root to the leaves, water and minerals move through the vessels due to transpiration, which results in a sucking force;
2) the upward current in the plant is promoted by root pressure, which occurs as a result of the constant supply of water to the root due to the difference in the concentration of substances in the cells and the environment.
23. Consider the cells shown in the figure. Determine what letters denote prokaryotic and eukaryotic cells. Provide evidence for your point of view.
Answer:
1) A - prokaryotic cell, B - eukaryotic cell;
2) the cell in figure A does not have a formed nucleus, its hereditary material is represented by a ring chromosome;
3) the cell in figure B has a well-formed nucleus and organelles.
24. What is the complication of the circulatory system of amphibians compared to fish?
Answer:
1) the heart becomes three-chambered;
2) the second circle of blood circulation appears;
3) the heart contains venous and mixed blood.
25. Why is a mixed forest ecosystem considered more sustainable than a spruce forest ecosystem?
Answer:
1) there are more species in a mixed forest than in a spruce forest;
2) in a mixed forest, food chains are longer and more branched than in a spruce forest;
3) there are more tiers in a mixed forest than in a spruce forest.
26. A section of a DNA molecule has the following composition: GATGAATAGTGCTTC. List at least three consequences that an accidental replacement of the seventh nucleotide of thymine with cytosine (C) can lead to.
Answer:
1) a gene mutation will occur - the codon of the third amino acid will change;
2) in a protein, one amino acid can be replaced by another, as a result, the primary structure of the protein will change;
3) all other protein structures can change, which will lead to the appearance of a new trait in the body.
27. Red algae (crimson) live at great depths. Despite this, photosynthesis occurs in their cells. Explain how photosynthesis occurs if the water column absorbs the rays of the red-orange part of the spectrum.
Answer:
1) for photosynthesis, rays are needed not only in the red, but also in the blue part of the spectrum;
2) purple cells contain a red pigment that absorbs the rays of the blue part of the spectrum, their energy is used in the process of photosynthesis.
28. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. Coelenterates are three-layer multicellular animals. 2. They have a gastric or intestinal cavity. 3. The intestinal cavity includes stinging cells. 4. Coelenterates have a mesh (diffuse) nervous system. 5. All intestinal - free-floating organisms.
1) 1 - coelenterates - two-layer animals;
2)3 - stinging cells are contained in the ectoderm, and not in the intestinal cavity;
3)5 - among the coelenterates there are attached forms.
29. How does gas exchange occur in the lungs and tissues in mammals? What is the reason for this process?
Answer:
1) gas exchange is based on diffusion, which is due to the difference in the concentration of gases (partial pressure) in the air of the alveoli and in the blood;
2) oxygen from the area of high pressure in the alveolar air enters the blood, and carbon dioxide from the area of high pressure in the blood enters the alveoli;
3) in the tissues, oxygen from the high pressure area in the capillaries enters the intercellular substance and then into the cells of the organs. Carbon dioxide from the area of high pressure in the intercellular substance enters the blood.
30. What is the participation of functional groups of organisms in the circulation of substances in the biosphere? Consider the role of each of them in the cycle of substances in the biosphere.
Answer:
1) producers synthesize organic substances from inorganic substances (carbon dioxide, water, nitrogen, phosphorus and other minerals), release oxygen (except for chemotrophs);
2) consumers (and other functional groups) of organisms use and convert organic substances, oxidize them during respiration, absorbing oxygen and releasing carbon dioxide and water;
3) decomposers decompose organic substances to inorganic compounds of nitrogen, phosphorus, etc., returning them to the environment.
31. A section of a DNA molecule encoding a sequence of amino acids in a protein has the following composition: G-A-T-G-A-A-T-A-G-TT-C-T-T-C. Explain the consequences of accidentally adding a guanine (G) nucleotide between the seventh and eighth nucleotides.
Answer:
1) a gene mutation will occur - the codes of the third and subsequent amino acids may change;
2) the primary structure of the protein may change;
3) a mutation can lead to the appearance of a new trait in an organism.
32. What plant organs are damaged by May beetles at different stages of individual development?
Answer:
1) plant roots damage larvae;
2) tree leaves damage adult beetles.
33. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. Flatworms are three-layered animals. 2. Type Flatworms include white planaria, human roundworm and liver fluke. 3. Flatworms have an elongated flattened body. 4. They have a well-developed nervous system. 5. Flatworms are dioecious animals that lay eggs.
Mistakes made in sentences:
1) 2 - the type of Flatworms does not include the human roundworm, it is a Roundworm;
2) 4 - in flatworms, the nervous system is poorly developed;
3) 5 - Flatworms - hermaphrodites.
34. What is a fetus? What is its significance in the life of plants and animals?
Answer:
1) fruit - generative organ of angiosperms;
2) contains seeds, with the help of which the reproduction and resettlement of plants occurs;
3) the fruits of plants are food for animals.
35. Most of the bird species fly away for the winter from the northern regions, despite their warm-bloodedness. Name at least three factors that cause these animals to migrate.
Answer:
1) food objects of insectivorous birds become unavailable for getting;
2) ice cover on water bodies and snow cover on the ground deprive herbivorous birds of food;
3) change in the length of daylight hours.
36. Which milk, sterilized or freshly milked, will go sour faster under the same conditions? Explain the answer.
Answer:
1) freshly milked milk will sour faster, as it contains bacteria that cause fermentation of the product;
2) when milk is sterilized, cells and spores of lactic acid bacteria die, and milk is stored longer.
37. Find errors in the given text. Indicate the numbers of sentences in which errors were made, explain them.
1. The main classes of the type of arthropods are Crustaceans, Arachnids and Insects. 2. The body of crustaceans and arachnids is divided into head, thorax and abdomen. 3. The body of insects consists of a cephalothorax and an abdomen. 4. Spider antennae don't. 5. Insects have two pairs of antennae, while crustaceans have one pair.
Mistakes made in sentences:
1) 2 - the body of crustaceans and arachnids consists of a cephalothorax and abdomen;
2)3 - the body of insects consists of a head, chest and abdomen;
3-5 - insects have one pair of antennae, and crustaceans have two pairs.
38. Prove that the rhizome of a plant is a modified shoot.
Answer:
1) the rhizome has nodes in which there are rudimentary leaves and buds;
2) at the top of the rhizome is the apical bud, which determines the growth of the shoot;
3) adventitious roots depart from the rhizome;
4) the internal anatomical structure of the rhizome is similar to the stem.
39. Man uses chemicals to control pests. Indicate at least three changes in the life of an oak forest if all herbivorous insects are destroyed in it by a chemical method. Explain why they will happen.
Answer:
1) the number of insect pollinated plants will decrease sharply, since herbivorous insects are pollinators of plants;
2) the number of insectivorous organisms (consumers of the second order) will sharply decrease or they will disappear due to disruption of food chains;
3) part of the chemicals used to kill insects will enter the soil, which will lead to disruption of plant life, death of soil flora and fauna, all violations can lead to the death of oak forests.
40. Why can antibiotic treatment lead to bowel dysfunction? Name at least two reasons.
Answer:
1) antibiotics kill beneficial bacteria that live in the human intestine;
2) fiber breakdown, water absorption and other processes are disturbed.
41. What part of the sheet is indicated in the figure by the letter A and what structures does it consist of? What are the functions of these structures?
1) the letter A denotes a vascular fibrous bundle (vein), the bundle includes vessels, sieve tubes, mechanical tissue;
2) vessels provide water transport to the leaves;
3) sieve tubes provide transport of organic substances from leaves to other organs;
4) mechanical tissue cells give strength and are the framework of the sheet.
42. What are the characteristic features of the fungi kingdom?
Answer:
1) the body of fungi consists of filaments - hyphae, forming a mycelium;
2) reproduce sexually and asexually (spores, mycelium, budding);
3) grow throughout life;
4) in the cell: the shell contains a chitin-like substance, a reserve nutrient - glycogen.
43. In a small reservoir formed after the flood of the river, the following organisms were found: ciliates-shoes, daphnia, white planarians, a large pond snail, cyclops, hydras. Explain whether this body of water can be considered an ecosystem. Give at least three pieces of evidence.
Answer:
The named temporary reservoir cannot be called an ecosystem, since in it:
1) there are no producers;
2) there are no decomposers;
3) there is no closed circulation of substances and food chains are broken.
44. Why is a note placed under the tourniquet, which is applied to stop bleeding from large blood vessels, indicating the time of its application?
Answer:
1) after reading the note, you can determine how much time has passed since the tourniquet was applied;
2) if after 1-2 hours it was not possible to deliver the patient to the doctor, then the tourniquet should be loosened for a while. This will prevent tissue necrosis.
45. Name the structures of the spinal cord, indicated in the figure by numbers 1 and 2, and describe the features of their structure and function.
Answer:
1) 1 - gray matter, formed by the bodies of neurons;
2) 2 - white matter, formed by long processes of neurons;
3) gray matter performs a reflex function, white matter - a conductive function.
46. What role do salivary glands play in digestion in mammals? List at least three functions.
Answer:
1) the secretion of the salivary glands moistens and disinfects food;
2) saliva is involved in the formation of the food bolus;
3) saliva enzymes contribute to the breakdown of starch.
47. As a result of volcanic activity, an island was formed in the ocean. Describe the sequence of ecosystem formation on a newly formed piece of land. List at least three items.
Answer:
1) the first to settle are microorganisms and lichens that provide soil formation;
2) plants settle on the soil, the spores or seeds of which are carried by wind or water;
3) as vegetation develops, animals appear in the ecosystem, primarily arthropods and birds.
48. Experienced gardeners apply fertilizer to the grooves located along the edges of the near-stem circles of fruit trees, and do not distribute them evenly. Explain why.
Answer:
1) the root system grows, the suction zone moves behind the root tip;
2) roots with a developed suction zone - root hairs - are located along the edges of the near-stem circles.
49. What modified shoot is shown in the picture? Name the elements of the structure, indicated in the figure by the numbers 1, 2, 3, and the functions that they perform.
Answer:
1) bulb;
2) 1 - juicy scaly leaf, in which nutrients and water are stored;
3) 2 - adventitious roots that ensure the absorption of water and minerals;
4) 3 - kidney, ensures the growth of the shoot.
50. What are the features of the structure and life of mosses? List at least three items.
Answer:
1) most mosses are leafy plants, some of them have rhizoids;
2) mosses have a poorly developed conducting system;
3) mosses reproduce both sexually and asexually, with alternation of generations: sexual (gametophyte) and asexual (sporophyte); an adult moss plant is a sexual generation, and a spore box is asexual.
51. As a result of a forest fire, part of the spruce forest burned out. Explain how it will self-heal. List at least three steps.
Answer:
1) herbaceous light-loving plants develop first;
2) then shoots of birch, aspen, pine appear, the seeds of which fell with the help of the wind, a small-leaved or pine forest is formed.
3) under the canopy of light-loving species, shade-tolerant spruces develop, which subsequently completely crowd out other trees.
52. To establish the cause of a hereditary disease, the patient's cells were examined and a change in the length of one of the chromosomes was found. What research method allowed to establish the cause of this disease? What kind of mutation is it associated with?
Answer:
1) the cause of the disease is established using the cytogenetic method;
2) the disease is caused by a chromosomal mutation - the loss or addition of a chromosome fragment.
53. What letter in the figure indicates the blastula in the development cycle of the lancelet. What are the features of blastula formation?
Answer:
1) the blastula is designated by the letter G;
2) the blastula is formed during the crushing of the zygote;
3) the size of the blastula does not exceed the size of the zygote.
54. Why are fungi isolated in a special kingdom of the organic world?
Answer:
1) the body of mushrooms consists of thin branching threads - hyphae, forming a mycelium, or mycelium;
2) mycelium cells store carbohydrates in the form of glycogen;
3) fungi cannot be attributed to plants, since their cells do not have chlorophyll and chloroplasts; the wall contains chitin;
4) mushrooms cannot be attributed to animals, since they absorb nutrients from the entire surface of the body, and do not swallow them in the form of food lumps.
55. In some forest biocenoses, mass shooting of diurnal birds of prey was carried out to protect chicken birds. Explain how this event affected the number of chickens.
Answer:
1) at first, the number of chickens increased, since their enemies (naturally regulating the number) were destroyed;
2) then the number of chickens decreased due to lack of food;
3) the number of sick and weakened individuals increased due to the spread of diseases and the absence of predators, which also affected the decrease in the number of chickens.
56. The color of the fur of a white hare changes throughout the year: in winter the hare is white, and in summer it is gray. Explain what type of variability is observed in an animal and what determines the manifestation of this trait.
Answer:
1) a manifestation of modification (phenotypic, non-hereditary) variability is observed in a hare;
2) the manifestation of this trait is determined by changes in environmental conditions (temperature, day length).
57. Name the stages of embryonic development of the lancelet, indicated in the figure by the letters A and B. Expand the features of the formation of each of these stages.
A B
Answer:
1) A - gastrula - the stage of a two-layer embryo;
2) B - neurula, has the beginnings of a future larva or adult organism;
3) the gastrula is formed by invagination of the blastula wall, and in the neurula, the neural plate is first laid, which serves as a regulator for laying the rest of the organ systems.
58. What are the main features of the structure and vital activity of bacteria. List at least four features.
Answer:
1) bacteria - pre-nuclear organisms that do not have a formalized nucleus and many organelles;
2) according to the method of nutrition, bacteria are heterotrophs and autotrophs;
3) high rate of reproduction by division;
4) anaerobes and aerobes;
5) unfavorable conditions are experienced in a state of dispute.
59. What is the difference between the ground-air environment and the water?
Answer:
1) oxygen content;
2) differences in temperature fluctuations (wide amplitude of fluctuations in the ground-air environment);
3) the degree of illumination;
4) density.
Answer:
1) seaweed has the ability to accumulate the chemical element iodine;
2) Iodine is essential for normal thyroid function.
61. Why is a shoe ciliate cell considered an integral organism? What organelles of ciliates-shoes are indicated in the figure by the numbers 1 and 2 and what functions do they perform?
Answer:
1) the ciliate cell performs all the functions of an independent organism: metabolism, reproduction, irritability, adaptation;
2) 1 - a small nucleus, participates in the sexual process;
3) 2 - a large core, regulates vital processes.
61. What are the features of the structure and life of fungi? List at least three features.
62. Explain the harm to plants caused by acid rain. Give at least three reasons.
Answer:
1) directly damage the organs and tissues of plants;
2) pollute the soil, reduce fertility;
3) reduce the productivity of plants.
63. Why are passengers advised to suck on lollipops when taking off or landing an airplane?
Answer:
1) a rapid change in pressure during takeoff or landing of an aircraft causes discomfort in the middle ear, where the initial pressure on the eardrum lasts longer;
2) swallowing movements improve the access of air to the auditory (Eustachian) tube, through which the pressure in the middle ear cavity equalizes with the pressure in the environment.
64. How does the circulatory system of arthropods differ from the circulatory system of annelids? Indicate at least three signs that prove these differences.
Answer:
1) in arthropods, the circulatory system is open, and in annelids it is closed;
2) arthropods have a heart on the dorsal side;
3) annelids do not have a heart, its function is performed by an annular vessel.
65. What type is the animal shown in the picture? What is indicated by numbers 1 and 2? Name other representatives of this type.
Answer:
1) to the type of intestinal;
2) 1 - ectoderm, 2 - intestinal cavity;
3) coral polyps, jellyfish.
66. What are the morphological, physiological and behavioral adaptations to environmental temperature in warm-blooded animals?
Answer:
1) morphological: heat-insulating covers, subcutaneous fat layer, changes in the surface of the body;
2) physiological: increased intensity of evaporation of sweat and moisture during breathing; narrowing or dilation of blood vessels, changes in the level of metabolism;
3) behavioral: construction of nests, burrows, changes in daily and seasonal activity depending on the temperature of the environment.
67. How is the receipt of genetic information from the nucleus to the ribosome?
Answer:
1) mRNA synthesis occurs in the nucleus in accordance with the principle of complementarity;
2) mRNA - a copy of the DNA section containing information about the primary structure of the protein moves from the nucleus to the ribosome.
68. What is the complication of ferns in comparison with mosses? Give at least three signs.
Answer:
1) ferns have roots;
2) in ferns, unlike mosses, a developed conductive tissue has formed;
3) in the development cycle of ferns, the asexual generation (sporophyte) prevails over the sexual (gametophyte), which is represented by the outgrowth.
69. Name the embryonic layer of a vertebrate animal, indicated in the figure by the number 3. What type of tissue and what organs are formed from it.
Answer:
1) germinal layer - endoderm;
2epithelial tissue (intestinal and respiratory epithelium);
3) organs: intestines, digestive glands, respiratory organs, some endocrine glands.
70. What role do birds play in the biocenosis of the forest? Give at least three examples.
Answer:
1) regulate the number of plants (distribute fruits and seeds);
2) regulate the number of insects, small rodents;
3) serve as food for predators;
4) fertilize the soil.
71. What is the protective role of leukocytes in the human body?
Answer:
1) leukocytes are capable of phagocytosis - devouring and digesting proteins, microorganisms, dead cells;
2) leukocytes are involved in the production of antibodies that neutralize certain antigens.
72. Find errors in the given text. Indicate the numbers of the proposals in which they are made, correct them.
According to the chromosome theory of heredity:
1. Genes are located on chromosomes in a linear order. 2. Everyone occupies a certain place - an allele. 3. Genes on one chromosome form a linkage group. 4. The number of linkage groups is determined by the diploid boron of chromosomes. 5. Violation of gene linkage occurs in the process of conjugation of chromosomes in the prophase of meiosis.
Mistakes made in sentences:
1)2 - location of the gene - locus;
2)4 - the number of linkage groups is equal to the haploid set of chromosomes;
3)5 - disruption of gene linkage occurs during crossing over.
73. Why do some scientists refer to green euglena as a plant, and others as an animal? List at least three reasons.
Answer:
1) capable of heterotrophic nutrition, like all animals;
2) capable of active movement in search of food, like all animals;
3) contains chlorophyll in the cell and is capable of autotrophic nutrition, like plants.
74. What processes take place at the stages of energy metabolism?
Answer:
1) at the preparatory stage, complex organic substances are split into less complex ones (biopolymers - to monomers), energy is dissipated in the form of heat;
2) in the process of glycolysis, glucose is broken down to pyruvic acid (or lactic acid, or alcohol) and 2 ATP molecules are synthesized;
3) at the oxygen stage, pyruvic acid (pyruvate) is broken down to carbon dioxide and water and 36 ATP molecules are synthesized.
75. In a wound formed on the human body, bleeding eventually stops, but suppuration may occur. Explain what properties of blood this is due to.
Answer:
1) bleeding stops due to blood clotting and the formation of a blood clot;
2) suppuration is due to the accumulation of dead leukocytes that have carried out phagocytosis.
76. Find errors in the given text, correct them. Indicate the numbers of sentences in which errors were made, explain them.
1. Proteins are of great importance in the structure and life of organisms. 2. These are biopolymers whose monomers are nitrogenous bases. 3. Proteins are part of the plasma membrane. 4. Many proteins perform an enzymatic function in the cell. 5. In protein molecules, hereditary information about the characteristics of an organism is encrypted. 6. Protein and tRNA molecules are part of ribosomes.
Mistakes made in sentences:
1) 2 - protein monomers are amino acids;
2)5 - hereditary information about the characteristics of the organism is encrypted in DNA molecules;
3)6- ribosomes contain rRNA molecules, not tRNA.
77. What is myopia? In what part of the eye is the image focused in a nearsighted person? What is the difference between congenital and acquired forms of myopia?
Answer:
1) myopia is a disease of the organs of vision, in which a person does not distinguish distant objects;
2) in a nearsighted person, the image of objects appears in front of the retina;
3) with congenital myopia, the shape of the eyeball changes (lengthens);
4) acquired myopia is associated with a change (increase) in the curvature of the lens.
78. What is the difference between the skeleton of the human head and the skeleton of the head of great apes? List at least four differences.
Answer:
1) the predominance of the brain of the skull over the facial;
2) reduction of the jaw apparatus;
3) the presence of a chin protrusion on the lower jaw;
4) reduction of superciliary arches.
79. Why is the volume of urine excreted by the human body per day not equal to the volume of liquid drunk during the same time?
Answer:
1) part of the water is used by the body or is formed in metabolic processes;
2) part of the water evaporates through the respiratory organs and sweat glands.
80. Find errors in the given text, correct them, indicate the numbers of the sentences in which they are made, write down these sentences without errors.
1. Animals are heterotrophic organisms; they feed on ready-made organic substances. 2. There are unicellular and multicellular animals. 3. All multicellular animals have bilateral body symmetry. 4. Most of them have developed various organs of locomotion. 5. Only arthropods and chordates have a circulatory system. 6. Postembryonic development in all multicellular animals is direct.
Mistakes made in sentences:
1) 3 - not all multicellular animals have bilateral symmetry of the body; for example, in coelenterates it is radial (radial);
2) 5 - the circulatory system is also present in annelids and mollusks;
3) 6 - direct postembryonic development is not inherent in all multicellular animals.
81. What is the importance of blood in human life?
Answer:
1) performs a transport function: delivery of oxygen and nutrients to tissues and cells, removal of carbon dioxide and metabolic products;
2) performs a protective function due to the activity of leukocytes and antibodies;
3) participates in the humoral regulation of the vital activity of the organism.
82. Use information about the early stages of embryogenesis (zygote, blastula, gastrula) to confirm the sequence of development of the animal world.
Answer:
1) the zygote stage corresponds to a unicellular organism;
2) the blastula stage, where cells are not differentiated, is similar to colonial forms;
3) the embryo at the gastrula stage corresponds to the structure of the intestinal cavity (hydra).
83. The introduction of large doses of drugs into a vein is accompanied by their dilution with saline (0.9% NaCl solution). Explain why.
Answer:
1) the introduction of large doses of drugs without dilution can cause a sharp change in the composition of the blood and irreversible phenomena;
2) the concentration of physiological saline (0.9% NaCl solution) corresponds to the concentration of salts in the blood plasma and does not cause the death of blood cells.
84. Find errors in the given text, correct them, indicate the numbers of the sentences in which they are made, write down these sentences without errors.
1. Animals of the arthropod type have an outer chitinous cover and jointed limbs. 2. The body of most of them consists of three sections: the head, chest and abdomen. 3. All arthropods have one pair of antennae. 4. Their eyes are complex (faceted). 5. The circulatory system of insects is closed.
Mistakes made in sentences:
1)3 - not all arthropods have one pair of antennae (arachnoids do not have them, and crustaceans have two pairs each);
2) 4 - not all arthropods have compound (compound) eyes: in arachnids they are simple or absent, in insects, along with compound eyes, they can be simple;
3-5 - the circulatory system in arthropods is not closed.
85. What are the functions of the human digestive system?
Answer:
1) mechanical processing of food;
2) chemical processing of food;
3) movement of food and removal of undigested residues;
4) absorption of nutrients, mineral salts and water into the blood and lymph.
86. What characterizes biological progress in flowering plants? List at least three features.
Answer:
1) a wide variety of populations and species;
2) wide settlement on the globe;
3) adaptability to life in different environmental conditions.
87. Why should food be chewed thoroughly?
Answer:
1) well-chewed food is quickly saturated with saliva in the oral cavity and begins to be digested;
2) well-chewed food is quickly saturated with digestive juices in the stomach and intestines and therefore easier to digest.
88. Find errors in the given text. Indicate the numbers of the proposals in which they are made, correct them.
1. A population is a collection of freely interbreeding individuals of the same species that inhabit a common territory for a long time. 2. Different populations of the same species are relatively isolated from each other, and their individuals do not interbreed. 3. The gene pool of all populations of the same species is the same. 4. The population is the elementary unit of evolution. 5. A group of frogs of the same species living in a deep puddle for one summer is a population.
Mistakes made in sentences:
1)2 - populations of the same species are partially isolated, but individuals of different populations can interbreed;
2)3 — gene pools of different populations of the same species are different;
3)5 - a group of frogs is not a population, since a group of individuals of the same species is considered a population if it occupies the same space for a large number of generations.
89. Why is it recommended to drink salted water in summer with prolonged thirst?
Answer:
1) in summer, sweating increases in a person;
2) mineral salts are excreted from the body with sweat;
3) salted water restores the normal water-salt balance between the tissues and the internal environment of the body.
90. What proves that a person belongs to the class of mammals?
Answer:
1) the similarity of the structure of organ systems;
2) the presence of hairline;
3) the development of the embryo in the uterus;
4) feeding offspring with milk, caring for offspring.
91. What processes maintain the constancy of the chemical composition of human blood plasma?
Answer:
1) processes in buffer systems maintain the reaction of the medium (pH) at a constant level;
2) neurohumoral regulation of the chemical composition of plasma is carried out.
92. Find errors in the given text. Indicate the numbers of the proposals in which they are made, explain them.
1. A population is a collection of freely interbreeding individuals of different species that inhabit a common territory for a long time. 2. The main group characteristics of a population are the number, density, age, sex and spatial structures. 3. The totality of all the genes of a population is called the gene pool. 4. Population is a structural unit of living nature. 5. The number of populations is always stable.
Mistakes made in sentences:
1)1 - a population is a collection of freely interbreeding individuals of the same species, inhabiting the common territory of the population for a long time;
2)4 - the population is a structural unit of the species;
3-5 - the number of populations can change in different seasons and years.
93. What structures of the integument of the body provide protection for the human body from the effects of environmental temperature factors? Explain their role.
Answer:
1) subcutaneous fatty tissue protects the body from cooling;
2) sweat glands form sweat, which, when evaporated, protects against overheating;
3) the hair on the head protects the body from cooling and overheating;
4) changing the lumen of skin capillaries regulates heat transfer.
94. Give at least three progressive biological features of a person, which he acquired in the process of long evolution.
Answer:
1) an increase in the brain and cerebral part of the skull;
2) upright posture and corresponding changes in the skeleton;
3) liberation and development of the hand, opposition of the thumb.
95. What division of meiosis is similar to mitosis? Explain how it is expressed and what set of chromosomes in the cell leads to.
Answer:
1) similarity with mitosis is observed in the second division of meiosis;
2) all phases are similar, sister chromosomes (chromatids) diverge to the poles of the cell;
3) the resulting cells have a haploid set of chromosomes.
96. What is the difference between arterial bleeding and venous bleeding?
Answer:
1) with arterial bleeding, scarlet blood;
2) it shoots out of the wound with a strong jet, a fountain.
97. The scheme of what process occurring in the human body is shown in the figure? What underlies this process and how does the composition of the blood change as a result? Explain the answer.
capillary
Answer:
1) the figure shows a diagram of gas exchange in the lungs (between the pulmonary vesicle and the blood capillary);
2) gas exchange is based on diffusion - the penetration of gases from a place with high pressure to a place with less pressure;
3) as a result of gas exchange, the blood is saturated with oxygen and turns from venous (A) to arterial (B).
98. What effect does hypodynamia (low motor activity) have on the human body?
Answer:
hypodynamia leads to:
1) to a decrease in the level of metabolism, an increase in adipose tissue, overweight;
2) weakening of the skeletal and cardiac muscles, increasing the load on the heart and reducing the endurance of the body;
3) venous blood stagnation in the lower extremities, vasodilation, circulatory disorders.
(Other formulations of the answer are allowed that do not distort its meaning.)
99. What are the characteristics of plants that live in arid conditions?
Answer:
1) the root system of plants penetrates deep into the soil, reaches the groundwater or is located in the surface layer of the soil;
2) in some plants, water is stored in leaves, stems and other organs during drought;
3) the leaves are covered with a wax coating, pubescent or modified into spines or needles.
100. What is the reason for the need for iron ions to enter the human blood? Explain the answer.
Answer:
2) erythrocytes provide transport of oxygen and carbon dioxide.
101. Through what vessels and what kind of blood enters the chambers of the heart, indicated in the figure by numbers 3 and 5? With what circle of blood circulation is each of these structures of the heart connected?
Answer:
1) venous blood enters the chamber marked with the number 3 from the superior and inferior vena cava;
2) the chamber marked with the number 5 receives arterial blood from the pulmonary veins;
3) the chamber of the heart, indicated by the number 3, is associated with a large circle of blood circulation;
4) the chamber of the heart, indicated by the number 5, is associated with the pulmonary circulation.
102. What are vitamins, what is their role in the life of the human body?
Answer:
1) vitamins - biologically active organic substances needed in small quantities;
2) they are part of enzymes, participating in metabolism;
3) increase the body's resistance to adverse environmental influences, stimulate growth, development of the body, restoration of tissues and cells.
103. The body shape of the Kalima butterfly resembles a leaf. How did a similar body shape form in a butterfly?
Answer:
1) the appearance in individuals of various hereditary changes;
2) preservation by natural selection of individuals with a modified body shape;
3) reproduction and distribution of individuals with a body shape resembling a leaf.
104. What is the nature of most enzymes and why do they lose their activity when the level of radiation increases?
Answer:
1) most enzymes are proteins;
2) under the action of radiation, denaturation occurs, the structure of the protein-enzyme changes.
105. Find errors in the given text. Indicate the numbers of proposals in which they are made, correct them.
1. Plants, like all living organisms, feed, breathe, grow, reproduce. 2. According to the method of nutrition, plants are classified as autotrophic organisms. 3. When breathing, plants absorb carbon dioxide and release oxygen. 4. All plants reproduce by seeds. 5. Plants, like animals, grow only in the first years of life.
Mistakes made in sentences:
1) 3 - when breathing, plants absorb oxygen and release carbon dioxide;
2-4 - only flowering and gymnosperms reproduce by seeds, and algae, mosses, ferns - by spores;
3-5 - plants grow throughout their lives, have unlimited growth.
106. What is the reason for the need for iron ions to enter the human blood? Explain the answer.
Answer:
1) iron ions are part of the hemoglobin of erythrocytes;
2) erythrocyte hemoglobin provides transport of oxygen and carbon dioxide, as it is able to bind to these gases;
3) the supply of oxygen is necessary for the energy metabolism of the cell, and carbon dioxide is its final product to be removed.
107. Explain why people of different races are classified as the same species. Give at least three pieces of evidence.
Answer:
1) the similarity of the structure, life processes, behavior;
2) genetic unity - the same set of chromosomes, their structure;
3) interracial marriages produce offspring capable of reproduction.
108. In ancient India, a person suspected of a crime was offered to swallow a handful of dry rice. If he did not succeed, the guilt was considered proven. Give a physiological justification for this process.
Answer:
1) swallowing is a complex reflex act, which is accompanied by salivation and irritation of the root of the tongue;
2) with strong excitement, salivation is sharply inhibited, the mouth becomes dry, and the swallowing reflex does not occur.
109. Find errors in the given text. Indicate the numbers of the proposals in which they are made, explain them.
1. The composition of the food chain of biogeocenosis includes producers, consumers and decomposers. 2. The first link in the food chain are consumers. 3. Consumers in the world accumulate energy absorbed in the process of photosynthesis. 4. In the dark phase of photosynthesis, oxygen is released. 5. Reducers contribute to the release of energy accumulated by consumers and producers.
Mistakes made in sentences:
1) 2 - the first link is the producers;
2) 3 - consumers are not capable of photosynthesis;
3)4 - oxygen is released in the light phase of photosynthesis.
110. What are the causes of anemia in humans? List at least three possible reasons.
Answer:
1) large blood loss;
2) malnutrition (lack of iron and vitamins, etc.);
3) violation of the formation of erythrocytes in the hematopoietic organs.
111. The wasp fly is similar in color and body shape to a wasp. Name the type of its protective device, explain its significance and the relative nature of fitness.
Answer:
1) type of adaptation - mimicry, imitation of the color and shape of the body of an unprotected animal to a protected one;
2) resemblance to a wasp warns a possible predator about the danger of being stung;
3) the fly becomes the prey of young birds that have not yet developed a reflex to the wasp.
112. Make up a food chain using all of the following objects: humus, cross-spider, hawk, great tit, housefly. Determine the consumers of the third order in the compiled chain.
Answer:
1) humus -> housefly -> spider-cross -> great tit -> hawk;
2) consumer of the third order - great tit.
113. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. Annelids are the most highly organized animals of the cut of other types of worms. 2. Annelids have an open circulatory system. 3. The body of the annelids consists of identical segments. 4. There is no body cavity in annelids. 5. The nervous system of annelids is represented by the peripharyngeal ring and the dorsal nerve chain.
Mistakes made in sentences:
1) 2 - Annelids have a closed circulatory system;
2) 4 - Annelids have a body cavity;
3-5 - the nerve chain is located on the ventral side of the body.
114. Name at least three aromorphoses in terrestrial plants that allowed them to be the first to master the land. Justify the answer.
Answer:
1) the emergence of integumentary tissue - the epidermis with stomata - contributing to protection against evaporation;
2) the appearance of a conducting system that ensures the transport of substances;
3) the development of a mechanical tissue that performs a supporting function.
115. Explain the reason for the great diversity of marsupials in Australia and their absence on other continents.
Answer:
1) Australia separated from other continents during the heyday of marsupials before the appearance of placental animals (geographical isolation);
2) the natural conditions of Australia contributed to the divergence of signs of marsupials and active speciation;
3) on other continents, marsupials were replaced by placental mammals.
116. In what cases does a change in the sequence of DNA nucleotides not affect the structure and functions of the corresponding protein?
Answer:
1) if, as a result of a nucleotide substitution, another codon appears that codes for the same amino acid;
2) if the codon formed as a result of a nucleotide substitution encodes another amino acid, but with similar chemical properties that does not change the structure of the protein;
3) if nucleotide changes occur in intergenic or non-functioning DNA regions.
117. Why is the relationship between pike and perch in the river ecosystem considered competitive?
Answer:
1) are predators, eat similar food;
2) live in the same reservoir, need similar conditions for life, mutually oppress each other.
118. Find errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. The main classes of the type of arthropods are Crustaceans, Arachnids and Insects. 2. Insects have four pairs of legs, and arachnids have three pairs. 3. The crayfish has simple eyes, and the cross-spider has complex eyes. 4. In arachnids, spider warts are located on the abdomen. 5. Spider-cross and Maybug breathe with the help of lung sacs and trachea.
Mistakes made in sentences:
1) 2 - insects have three pairs of legs, and arachnids - four pairs;
2) 3 - crayfish has compound eyes, and the cross-spider has simple eyes;
3-5 - the May beetle does not have lung sacs, but only tracheae.
119. What are the features of the structure and life of cap mushrooms? List at least four features.
Answer:
1) have a mycelium and a fruiting body;
2) reproduce by spores and mycelium;
3) according to the method of nutrition - heterotrophs;
4) most form mycorrhiza.
120. What aromorphoses allowed the ancient amphibians to master the land.
Answer:
1) the appearance of pulmonary respiration;
2) the formation of dissected limbs;
3) the appearance of a three-chambered heart and two circles of blood circulation.
Assignments from the USE bank in biology with a free answer
1. The biological oxidation of organic substances in the human body is similar in chemical process to the combustion of fuel (coal, peat, wood). What products, common with combustion, are formed as a result of these processes? Compare the energetics of the processes of biological oxidation and combustion. What is their difference?
1) as a result of the oxidation of organic substances by oxygen, as in combustion, carbon dioxide and water are formed;
2) during combustion, all energy is released in the form of heat, and during biological oxidation, part of the energy is stored in ATP molecules
2. Why, according to the rule of the ecological pyramid, in the terrestrial food chain from link to link, there is a decrease in energy?
1) the energy contained in organic substances at each link in the food chain is spent on life processes;
2) part of the energy is dissipated in the form of heat.
3. Why does the nasal cavity need to be moist and clean for normal smell perception? Explain the answer.
1) the cavity must be moistened, since the olfactory cells (receptors) are irritated only by substances dissolved in the mucus of the nasal cavity;
2) abundant secretion of mucus prevents the access of substances to olfactory receptors
4. Make up a food chain using all the named representatives: cruciferous fleas, polecat, snake, turnip leaves, frog. Determine the consumer of the second order in the compiled chain and explain your choice.
1) turnip leaves → cruciferous fleas → frog → snake → polecat;
2) consumer of the second order - a frog, as it feeds on consumers of the first order
Response elements:
1) wet seeds will begin to germinate, while they breathe intensively and release a lot of heat;
2) strong heating of a large number of seeds leads to the death of both germinated and non-germinated seeds
6. What are the formations on the roots of the depicted plant? What type of relationship between organisms does the picture illustrate? Explain the meaning
these relationships for both organisms.
Response elements:
1) formations on the roots of a leguminous plant - these are nodules containing nodule bacteria;
2) the type of mutually beneficial relationship - a symbiosis of bacteria (nitrogen-fixing bacteria) and a leguminous plant;
3) nodule bacteria feed on plant organic matter;
4) nodule bacteria fix atmospheric nitrogen and provide legumes with nitrogen compounds
7. Using the diagram, identify the isolation method that led to the emergence of three related subspecies of the great tit and explain its consequences. To what result of evolution can their reproductive isolation lead?
Response elements:
1) geographical isolation led to the emergence of three subspecies of the great tit;
2) as a result of geographical isolation, interbreeding and gene exchange between individuals of different populations ceases,
each population forms its own gene pool;
3) Reproductive isolation can lead to the formation of three related species of tits
8. The figure shows a diagram of speciation according to Ch. Darwin. What evolutionary process
leads to the formation of the new species shown in Figure III? What driving forces (factors) of evolution underlie this process? What form of natural selection takes place in this case?
Response elements:
1) divergence (divergence) of signs;
2) divergence is due to hereditary variability, the struggle for existence and natural selection;
3) driving (disruptive) form of natural selection
8. Name the departments of the visual analyzer, indicated in the Figure by numbers 1 and 2. What function does each of these departments perform?
Response elements:
1) 1 - peripheral section (or retina, or receptors);
2) 2 - conduction department (or optic nerve);
3) the retina perceives and converts light stimulation
into nerve impulses;
4) the optic nerve transmits nerve impulses to the brain
9. Name the animal shown in the picture and indicate its type. What organ systems are marked with numbers 1 and 2? What functions do they perform?
Response elements:
1) the lancelet is depicted; type Chordates;
2) 1 - the nervous system - is involved in the nervous regulation of all functions of the body and the relationship with the environment;
3) 2 - digestive system (gut) - digests food and absorbs nutrients
10. Find three errors in the given text. Indicate the numbers of sentences in which errors were made, correct them.
1. Fungi and bacteria are classified as prokaryotes. 2. There is a wide variety among fungi: yeasts, molds, cap mushrooms, etc. 3. A common feature of multicellular fungi is the formation of a vegetative body from thin branching filaments that form a mycelium. 4. A fungal cell has a cell wall consisting of chitin and membrane organelles. 5. The reserve nutrient is glycogen. 6. Mushrooms have an autotrophic type of nutrition. 7. Mushroom growth stops after spores mature.
Response elements: Mistakes in sentences:
1) 1 - fungi are eukaryotes;
2) 6 - fungi have a heterotrophic type of nutrition;
3) 7 - mushrooms grow throughout life
The thyroid gland regulates the exchange of potassium, as it greatly affects the functioning of the nervous system. The fact is that the transmission of a nerve impulse is based on the sodium-potassium pump, in which potassium and sodium ions migrate through the membrane. A similar question was in the test part of the USE 2017: it was necessary to match which of the two glands regulates potassium metabolism, the pancreas or the thyroid. The problem is that there was no clear answer to this question in any textbook and manual on biology.
Dispute: embryo or cell?
One of the students wrote that a spore is a single-celled plant embryo. This is not true. A spore is a haploid cell used for asexual reproduction or for spreading. What is the fate of the controversy? In plants, it divides by mitosis. For example, in flowering plants, the male spore turns after two mitoses into two sperm and a vegetative cell. And the female spore inside the flower divides by mitosis three times and ensures the formation of eight nuclei of the embryo sac of the ovule. The embryo in plants is formed from the zygote after fertilization. From it, a seed is formed in gymnosperms and flowering plants. I come to the conclusion that the tutor and parents need to check the hourly plan for preparing students' homework for each week. As soon as each student follows his plan persistently and strictly, the score on the exam will skyrocket.
What does the genetic code encode?
One of the students gave a strange explanation that "the table of the genetic code encodes mRNA." If something is encoded in it, then mRNA triplets encode amino acids. It is incorrect to write that the table itself encodes something. Now I am talking about a standard problem in cytology. The problem is that it requires an explanation. As you can see, students often write something strange. In a specific task, it was necessary to write as follows: “Amino acids are encoded by mRNA triplets that are complementary to tRNA anticodons. Let us find the CGU mRNA triplet by the HCA tRNA anticodon. Next, we look at the table for the amino acid that it encodes - Arg. This is the correct text of the answer, if you are given a tRNA anticodon in the task of cytology (question 27).
Head of cabbage, "protein" shell and reproduction of amphibians
The key idea of the answers to the exam in biology: you must give the most complete, detailed answer. Short, short answers are not appropriate. They rarely reveal the full meaning. For example, a student did not write that a head of cabbage is a modified shoot. Outcome: 1 point removed. Yes, the head of cabbage is actually also a kidney, but also an escape! And this is important to point out. In addition, we must remember that the kidney is a rudimentary shoot. In this case, a head of cabbage is not a typical kidney, but a modified one. Minor inaccuracies in the writing of the answer also lead to the loss of points. For example, a student wrote not “protein”, but “protein” shell. Ball removed. The "protein" shell of the eye does not exist.
If you saw amphibians (frogs) in the picture that mate, this does not mean that they have internal fertilization. In many frogs, it is external (external), like in most amphibians. But, of course, there are tailed amphibians with internal fertilization.
Morphological changes arose in human ancestors
Here is another bright question of the USE 2017. “What morphological changes arose in human ancestors in the process of the formation of upper limbs in order to make fire and use tools?” Perhaps the question in the reference version sounded a little differently. But while I have it in this form (passed by the students).
1. Development of a five-fingered upper limb of a grasping type and a hand with a large number of movable joints.
2. Opposition of the thumb to the others (and its development), which provides fine manipulations of the hands.
3. The development of the muscles of the upper limbs, the shoulder girdle, changes in the structure of the axial skeleton, limb girdles and free limbs (extension of the chest, shortening of the upper limbs, reduction in their size) - all this provided the hands with greater mobility.
4. An increase in the volume of the brain, the growth of the cerebral cortex provided a person with a more complex behavior necessary for conscious and labor activity.
I see no point in commenting on every point. The only point: paragraph 3 could be expanded in more detail in terms of disclosing the changes due to upright posture. But note, this is a pretty general question. The process of limb formation went in parallel with the development of the brain, as described in paragraph 4. Let me remind you that in the USE question about changes in the skeleton due to work, we mention not only the opposition of the thumb, but also the predominance of the cerebral part of the skull over the facial.
They were grouped into seven content blocks: Biology is the science of wildlife; Cell as a biological system; The organism as a biological system; System and diversity of the organic world; Man and his health; The evolution of living nature; Ecosystems and their inherent patterns.
The examination paper consisted of three parts.
Part 1 included 36 tasks with the choice of one correct answer out of four, of which 26 were basic and 10 were advanced levels of complexity.
Part 2 - 8 high-level tasks: 3 - with the choice of several correct answers out of six, 3 - to establish a correspondence between biological objects, processes and phenomena, 2 - to determine the sequence of phenomena and processes.
Part 3 consisted of 6 tasks with a detailed answer: 1 - advanced and 5 - high level. All tasks of part 3 controlled the ability of graduates to independently express their thoughts, solve biological problems, explain facts, use them to formulate a conclusion, generalization. In part 3, the following lines were highlighted:
C1 - practice-oriented tasks;
C2 - tasks for working with text or drawing;
C3 - tasks for generalization and application of knowledge about a person, a variety of organisms;
C4 - tasks on evolution and ecology;
C5 - tasks in cytology,
C6 - genetic tasks.
Block 1. Biology - the science of wildlife
The task turned out to be difficult, requiring the determination of the level of organization of the living, at which protein structures are studied. Instead of the molecular level, students chose the cellular and organismal levels. The coniferous forest ecosystem was attributed by about half of the examinees to the biospheric level of life organization instead of the biocenotic one.
Block 2. Cell as a biological system
The greatest difficulties and problems arose for the USE participants when answering tasks that require comparison of eukaryotic and prokaryotic cells, RNA- and DNA-containing viruses, mitosis and meiosis, various phases of cell division, stages of energy metabolism; knowledge of the relationship between the structure and functions of organelles and chemical substances of the cell, their participation in metabolic processes; determination of the chromosome set of somatic and germ cells.
Particular attention should be paid to the performance of task C5 by the examinees, which offered three types of tasks in cytology: the application of knowledge about the genetic code, the determination of the number of chromosomes and DNA in different phases of mitosis and meiosis, and the substantiation of metabolic processes.
The examinees made a mistake when performing a task that required determining a fragment of a tRNA molecule and its anticodon by the nucleotide sequence of DNA, as well as determining the amino acid that this tRNA carries. The participants did not take into account the fact that the entire sequence of the mRNA fragment cannot be determined from a fragment of one tRNA molecule, but only its codon, which corresponds to the anticodon, can be determined. They split tRNA into triplets, determined mRNA by tRNA, and found the amino acid sequence from the obtained triplets. According to this answer, one tRNA molecule turned out to be simultaneously a template for the synthesis of mRNA and protein, which is a gross mistake. When preparing for the exam, you should review the material on protein biosynthesis, the translation process and the role of tRNA in it.
The tasks of determining the number of chromosomes and DNA in different phases of mitosis and meiosis turned out to be especially difficult. Typical mistakes that were made include the following:
1) the concepts of DNA replication and chromosome doubling are identified. In interphase, before the start of division, the number of DNA molecules doubles, two sister chromatids are formed, but the number of chromosomes does not change, since the chromatids are linked by the centromere and make up one chromosome. The number of chromosomes in a cell increases and becomes equal to the number of DNA only in the anaphase of any division, since sister chromatids, separating, become sister chromosomes;
2) there is often no explanation for each phase of the division, which was required to be given according to the condition of the problem;
3) in a significant part of the work, the participants determined the number of chromosomes, but did not determine the number of DNA molecules, as was required in the condition of the problem.
When performing tasks that required tracing the transformation of energy or the path of hydrogen in the process of metabolism, participants most often described the entire process, but did not answer the specific question provided for in the task.
For example, in response to a task in which it was required to trace the path of hydrogen in the light and dark stages of photosynthesis from the moment of its formation to the synthesis of glucose, it was necessary to indicate: 1) the formation of hydrogen ions during the photolysis of water under the action of sunlight, 2) the combination of hydrogen with NADP+ carrier and the formation of NADP.2H, 3) the use of NADP.2H in the reduction reaction of intermediates from which glucose is synthesized.
Block 3. Organism as a biological system
The examinees found it difficult to define parthenogenesis as a special kind of sexual reproduction, which organisms it is inherent in. Serious problems arose in answering questions about the individual development of organisms. Many USE participants in biology do not know well the cycles of plant development, the alternation of gametophyte and sporophyte in mosses and ferns; find it difficult to compare the stages of development of the animal embryo (neurula and gastrula), to determine the sequence of processes occurring during gametogenesis.
Particularly difficult were tasks in genetics, in which it was required to determine the chromosome set of the genome, its difference from the karyotype and genotype, the number of alleles in gametes, the ratio of offspring in monohybrid crossing. In order to avoid such mistakes in the future, it is recommended to repeat the material on meiosis before starting the study of genetics, since it underlies the formation of gametes and the inheritance of traits.
Block 4. System and diversity of the organic world
Poorly learned material on the structure and vital activity of bacteria and fungi. In particular, the participants found it difficult to distinguish between bacteria and unicellular plants, to determine the mode of nutrition of decay bacteria. They did not master the concepts of "mycorrhiza", "symbiosis", they could not determine the mold fungus mukor from the drawing, although its image is in every biology textbook. Of the practice-oriented tasks (C1), the lowest indicators were found when completing the task on the causes of the spread of porcini mushrooms in forests. The examinees could not explain the reasons for the spread of fungi that form symbiosis with plants. Instead, environmental factors were named: heat, humidity, shading, soil characteristics.
In the section “Plants”, the greatest difficulties were caused by questions of a physiological nature (transport of water, mineral and organic substances; the role of root pressure and transpiration in these processes), the principles of classification of flowering plants, aromorphic features of ferns, alternation of generations in higher spore plants. Most of the examinees coped poorly with the task C2, which required to determine its characteristics and belonging to the dicotyledonous class from the drawing of strawberries. The participants correctly identified the class of the depicted plant, however, for this they did not use the drawing, but their knowledge of the traits of the dicotyledonous class that were not shown in the drawing (two cotyledons, cambium in the stem, tap root system). They could not explain the formation of adventitious roots in strawberries, growing from the above-ground shoot (whiskers) and not being a sign of dicotyledonous plants, but pointed only to the tap root system with an undeveloped main root.
Tasks that control knowledge about invertebrates remain traditionally difficult: signs of complication of annelids (the appearance of a closed circulatory system), isolation of the anterior end of the body due to the appearance of bilateral symmetry, features of bivalves (shell structure, pearl formation), insects with complete and incomplete transformation , the importance of the salivary glands in the formation of the cocoon and the pupal stage.
Low results were also obtained in responses to individual questions of the Chordata type. Graduates do not know the type of nervous system of chordates, find it difficult to determine the parts of the brain of vertebrates from the drawing, cannot name the progressive features of mammals compared to reptiles, and explain the adaptability of amphibians to life in water and on land.
When compiling the article, materials were used:
1. Analytical report on the results of the USE 2011 www.fipi.ru
2. Specification of control measuring materials for the unified state exam in biology in 2012. Federal Institute of Pedagogical Measurements www.fipi.ru
Secondary general education
Line UMK VV Pasechnik. Biology (10-11) (base)
Line UMK I. N. Ponomareva. Biology (10-11) (base)
Line UMK I. N. Ponomareva. Biology (10-11) (deep)
Line UMK N. I. Sonina. Biology (10-11) (B)
Preparing for the exam in biology. Task 22
The USE 2018 will be more difficult than the exams of previous years. In particular, task No. 22, which was not given to everyone before, can cause serious difficulties. Georgy Lerner, who for many years served as deputy chairman of the Subject Committee on Biology, presents general advice on preparing for the exam and possible formulations of the creative task.
What to expect this year?
The committee has been updated. Experts tend to present tasks aimed at general learning skills, including creative ones, this is due to the orientation towards a new education system.
Students will have to show knowledge of all sorts of subtleties and details. Graduates need to repeat the respiratory system and be able to compare it with the respiratory systems of other organisms, know the properties of each department of the digestive and nervous systems. And not just to learn the facts from the textbook, but also to be able to interpret, explain, correlate, connect.
This year, there may be questions about the interpretation of the experimental data. To give the correct answer, the student will need methodological terminology. In addition, it is necessary to work out questions on knowledge of breeding, biotechnology, methods for obtaining new varieties of plants, breeds, medicines - they will be given considerable attention in the exam.
Experts note that in preparing for the exam, it is important to delegate most of the work directly to the student. The teacher should play the role of a consultant and proofreader, and it is better for the child to work through the material on his own.
Sample Questions
Task No. 22 remains practice-oriented and two-point (assessed according to two criteria). Using the example of possible formulations of this task, we will consider which topics should be given special attention in preparation.
Research methods
Example 1: The onion peel was placed in a concentrated salt solution. Explain what will happen in the cells. What scientific methods are used in this study?
In the answer, it is necessary to indicate such methods as experiment and microscopy (observation), and also to clarify that in cells there will be a detachment of the protoplast (cytoplasm) from the cell wall (plasmolysis) due to the fact that water from the cell enters the solution, where the salt concentration is higher (due to osmosis).
Example 2:Boys with Klinefelter's syndrome have a set of sex chromosomes - XXY. Explain how such an anomaly could have arisen. What method allows you to install it?
Children easily solve such tasks, but sometimes they get confused in the methods. In this case, we see a violation of meiosis in the maternal or paternal organism, which during gametogenesis leads to the formation of gametes containing XX or XY chromosomes, respectively. Method: cytogenetic (microscopy).
Analyzing cross
Example: A hornless black bull has been purchased for the farm and they want to make sure that it is purebred (these traits dominate over the horn and red color of the coat). What crossbreeding should be carried out and what offspring should be obtained if the bull is purebred?
In the answer, it is necessary to designate the term "analyzing cross". If the purchased bull is purebred (AABB), then all the offspring will be hornless, black (AaBv).
uncommon plants
Example 2:Explain the biotic relationship between tropical forest trees and the orchids that inhabit them.
plant hormones
Example:The inflorescence of a sunflower - a basket - is constantly turned towards the sun. Explain what plant mechanism provides this turn.
To answer, the student needs to understand the mechanism of the change in the shape of the plant, depending on which cells are the targets. Plant hormones cause an increase in the size of cells in the shade (due to an increase in turgor in them), and the difference in cell size bends the stem, exposing the inflorescence to the sun.
Respiratory system
Example: Consider the model developed by the Dutch physiologist Francis Donders. What process mechanism does this device demonstrate? Why does the volume of bags attached to glass tubes change when the position of the rubber membrane changes.
The question concerns a device installed in almost every biology classroom, and points to the mechanism of inhalation and exhalation. At the same time, it must be remembered that the diaphragm, which the rubber membrane imitates, is not a respiratory organ, but a striated muscle. In the answer to this question, it is also necessary to indicate: when the rubber membrane inside the can is lowered, the pressure decreases, becomes lower than atmospheric pressure, and the rubber bags increase in volume due to the pressure difference.
The proposed notebook is part of the educational complex for the textbook by V.I. Sivoglazova, I.B. Agafonovai, E.T. Zakharova "Biology. General biology. Grade 11". The textbook complies with the Federal State Educational Standard, is recommended by the Ministry of Education and Science of the Russian Federation, and is included in the Federal List of Textbooks.
Process energy
Example: What do you think is the advantage of internal fertilization in animals compared to external fertilization?
In response, it is important for the student to write that the formation of germ cells is decreasing, that is, the body's resources are used rationally. In addition, the likelihood of fertilization increases, and it is less dependent on external factors.
Roots
Example:Why do thick seedlings of carrots and beets need to be thinned out to get a good harvest? Explain the answer.
It should be pointed out that the thinning of plants weakens competition and leads to an increase in yield. It would also be quite reasonable to mention the lack of minerals in the close growth of seedlings. But the student will not receive the highest two points if it is not highlighted that the presented plants - carrots and beets - form root crops, the formation of which requires a significant amount of soil.
hybrids
Example 1: Currently, heterosis broiler chickens are widely used in poultry farming. Why are they widely used to solve food problems? How are they taken out?
To answer, it is important to understand that broilers are a hybrid, not a breed of chicken, so they are not able to fully inherit their genes. Broiler chickens are obtained by crossing pure lines, and in hybrids of the first generation, the effect of heterosis is manifested. It is also necessary to indicate that broiler chickens are characterized by intensive growth and quickly gain weight.
Example 2:Why are plant interspecific hybrids mostly sterile? By what method did G.D. Karpechenko overcame the sterility of an interspecific cabbage-radish hybrid?
In the answer, the student needs to write down that there are no pairs of homologous chromosomes in the interspecific hybrid, and this disrupts the process of meiosis and leads to sterility of the hybrids. As for G.D. Karpechenko, he overcame the sterility of the cabbage-radish hybrid by the method of polyploidy.
Ecosystem changes
Example: What initial changes will occur in the ecosystem of the lake with a decrease in the number of predatory fish?
This question is hotly debated, because it is not always clear how long the initial changes last. In addition, teachers and students often delve into forecasts. In fact, this question does not require a detailed answer, and implies an emphasis on two concepts: "original" and "reduction" (not disappearance!). Suffice it to point out that the number of herbivorous organisms will increase and the number of plants that feed on first-order consumers will decrease.
Enzymes and Substrates
Example: A German proverb says: "Well chewed is half overcooked." Explain its meaning from the position of the physiology of digestion in the oral cavity and stomach.
In the answer, it is necessary to indicate that prolonged chewing of food contributes to the release of gastric juice, and this facilitates digestion in the stomach. With careful chewing, food is crushed, well wetted by saliva and begins to be digested. The question assumes that we will talk, among other things, about increasing the working surface - due to the grinding of food and, accordingly, the increase in the activity of the interaction of enzymes with the substrate. Children most often answer this question inaccurately: they describe in detail the activity of enzymes or simply indicate that food is better digested.
Glucagon
Example:What are the consequences of a decrease in the synthesis of glucagon by the pancreas? What is the mechanism of action of this hormone?
The student must understand that glucagon regulates blood sugar just like insulin does. But this hormone, accumulating in the liver, breaks down glycogen if necessary and stimulates the release of glucose into the blood. Possible answer: glucagon works with insulin to regulate blood glucose levels, and as a drug it is used to increase glucose levels. It should also be pointed out that a decrease in glucagon levels can lead to diabetes mellitus.
The notebook contains various creative questions and tasks, including laboratory work, tasks, tables, diagrams and drawings, as well as test tasks that will help prepare for the exam.
Pests of agricultural plants
Example:To combat pests of agricultural plants in special laboratories, tiny insects are bred - Trichogramma, which lay their eggs in the eggs of insect pests. What is the name of this method of pest control of cultivated plants and what advantages does it have in comparison with other methods of control?
In the answer, it is important to state that this is a biological way to control pests of cultivated plants, and it does not pollute the environment, does not have a negative effect on plants.
reflexes
Example:Why can a dog that is deprived of food bite not only a stranger, but sometimes the owner?
There are a lot of tasks for knowledge of the nervous system, the reflex activity of the body, the work of the parasympathetic nervous system. The student needs to know how the autonomic nervous system works, what inhibition, excitation, conditioned and unconditional inhibition are. In answering this question, it must be pointed out that while eating, the dog’s digestive center is excited, and when food is taken away from it, external (unconditional) inhibition occurs in this center, the defense center is excited, and a defensive reflex manifests itself. An answer is also possible: the unconditioned protective reflex inhibits the unconditioned food reflex.
Genetics
Example:Why do sons in a family of healthy parents suffer from hemophilia?
All types of genetics questions remain this year, covering mono and dihybrid crosses, complete and incomplete dominance, sex-linked and sex-linked inheritance. In this example, it is necessary to indicate that the hemophilia gene is recessive, sex-linked and located on the X chromosome, and that it appears in boys, since they have one X chromosome, and the allele of this gene is absent on the Y chromosome.
The handbook contains detailed theoretical material on all topics tested by the USE in biology. After each section, multi-level tasks are given in the form of the exam. For the final control of knowledge at the end of the handbook, training options are given that correspond to the exam. Students do not have to search for additional information on the Internet and buy other manuals. In this guide, they will find everything they need to independently and effectively prepare for the exam. The reference book is addressed to high school students to prepare for the exam in biology. The manual contains detailed theoretical material on all topics tested by the exam. After each section, examples of USE tasks and a practice test are given. For the final control of knowledge at the end of the handbook, training options are given that correspond to the exam in biology. All questions are answered. The publication will be useful to biology teachers, parents for the effective preparation of students for the exam.
Blood pressure
Example:Why is a large blood loss dangerous for human life? Explain the answer.
The student needs to be prescribed that with a decrease in the amount of blood, blood pressure drops significantly (blood flow to the heart and brain decreases), after which oxygen starvation occurs (metabolism and energy production decrease in the tissues), and this can cause death of a person.
Consumers and food chains
Example 1: In what cases do blood-sucking insects occupy the position of consumers of the II, III and even IV orders in food chains?
This question can cause difficulties for graduates. Ultimately, they must indicate that on the body of a herbivore, blood-sucking insects are consumers of the second order, and on the body of a predator they are consumers of the third and fourth orders. When preparing, you need to consider examples from life: on a mouse, a mosquito is a consumer of the II order, and on a fox - III, while in the chain frog - snake - bird of prey, it may turn out to be a consumer of the IV order.
Example 2: Make up a food chain using all the named representatives: field mouse, meadow plants, fox, hawk. How much energy is transferred to the second order consumer level if the net annual primary production of the ecosystem is 10,000 kJ?
The meaning of the task may vary depending on the order of the consumer. In this case, the student needs to display the chain “Meadow plants –> vole mouse –> fox –> hawk”. And also indicate that 100 kJ passes to the fox, a consumer of the second order.
When preparing, it is imperative to warn schoolchildren that until they have read the assignment to the end and truly understand the meaning of the question, it is better not to start solving it. Even people who know the subject sometimes have a reflex: it seems to them that the question is clear from the first two or three phrases - this delusion can lead to an error. It is also worth reminding students of the benefits of working with drafts, especially in stressful situations like exams.