Living cells. Big world of small cells
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5. Living cells
This happened more than 300 years ago. The English scientist Robert Hooke examined under a microscope a thin section of a bottle cap made from the bark of a cork oak tree. What Hooke saw was a great discovery. He discovered that the cork consisted of many small cavities, chambers, which he called cells. It was soon discovered that other parts of plants also consist of cells. Moreover, it was discovered that the bodies of animals and humans are built from cells.
Hooke's microscope. Section of a cork under a microscope
If we could shrink ourselves a million times, amazing possibilities would open up for us. We could go inside cells and explore them the way travelers explore mysterious jungles, caves, or the depths of the sea. If we were tireless and visited the inside of a variety of organisms, we would be able to find out the following.
No matter how diverse the living creatures that inhabit our planet are, they all have a cellular structure. The bodies of plants, animals, and humans are built from cells, like houses made of bricks. Therefore, cells are often called the “building blocks” of the body. But this is a very, very rough comparison.
Firstly, the cells are complex, not like bricks fashioned from clay. Each cell has three main parts: outer membrane who dresses the cage, cytoplasm– a semi-liquid mass that constitutes the main contents of the cell, and core- a small dense body located in the cytoplasm.
Secondly, our “building blocks” are alive. They breathe, eat, grow... and divide. One cell turns into two. Then from each new one, when it grows, two more. Thanks to this, the entire body grows and develops.
This is what a modern microscope looks like
And finally, thirdly, in the body there are most often many types of cells. They differ from each other in shape and size. For example, the cells that form muscles, bones, and the nervous system in the human body look completely different. There are also special cells - sexual. They are different for men and women. The female reproductive cell is called egg, and male cells – spermatozoa. These cells give rise to a new organism; in other words, children are born thanks to them. For this to happen, the egg and sperm must unite. Their merger is called fertilization. The fertilized egg divides many times, and an embryo develops from it. Human development in the mother's body lasts 9 months. When a child is born, it is difficult to believe that life was given to him by only two small cells - the mother's egg and the father's sperm.
There are approximately 200 types of cells in the human body. And their total number is about 100 trillion. This number is written like this: 100,000,000,000,000.
Big world of small cells*
We already know that the body of any plant, animal, or human has organs. The cell also has “organs”. They are located in the cytoplasm and are called organoids, i.e. “similar to organs.” You can see some of them in the picture. Mitochondria are responsible for cell respiration, lysosomes are responsible for digestion. And the network of channels resembles blood vessels - through them different substances pass from one part of the cell to another.
Almost all cells are very small. You can't see them without a microscope. And you have all seen the chicken egg more than once: this is the yolk of the egg. Huge cage! It is even greater in an ostrich egg: after all, about 30 chicken eggs could fit in it.
The eggs of fish and frogs - eggs - are much smaller than those of birds. But they are also much larger than most other cells.
The eggs are so large because they contain a large supply of nutrients necessary for the development of the embryo.
Many plant cells contain special green organelles - chloroplasts(from the Greek “chloros” - green). They give the plant its green color. Chloroplasts are very important for plants: it is in them that nutrients are formed in the light.
Questions and tasks
1. What is the unit of structure of living things? What is it called and who gave it that name?
2. How long ago did people know that the bodies of living beings consist of cells? Explain why this was not known before.
3. Are there cells that can be seen without a microscope? If yes, please provide examples.
4. Look at the drawing. Name the main parts of a living cell.
5. What features of cells indicate that they are alive?
6. The human body originates from a single cell, formed as a result of the fusion of two germ cells. An adult body consists of approximately 100 trillion cells. Where do so many cells come from?
7. Consider the cells of different parts of the plant and the human body in the picture. Why do you think there are so many types of cells in one organism? Try to tell by their appearance what kind of work they do.
8.* Explain why eggs are much larger than most other cells.
Living things have a cellular structure. The main parts of a cell are the outer membrane, cytoplasm and nucleus. Living cells breathe, eat, grow, and divide. They are varied in shape and size. Among them are germ cells that give rise to a new organism.
6. Chemical composition of the cell
You already know that all living organisms are similar in structure: they consist of cells. But it turns out that their chemical composition is also similar - the cells of all organisms consist of the same elements. Currently, scientists have been able to detect more than 80 chemical elements out of 111 known in the cell.
Elements found in a living cell are also widespread in inanimate nature - the atmosphere, water, and the earth's crust. There are no elements that are found only in living organisms.
Most elements are found in the cell in the form of chemical compounds - substances. There are inorganic and organic substances.
The most common inorganic substance in a living organism is water, its content averages up to 80% of body weight. Even tooth enamel contains 10% water, and bones contain up to 20%. This is explained by the role that water plays in the cell. First of all, it determines the physical properties of the cell, its volume, elasticity. Numerous chemical reactions take place in an aqueous environment, since water is a good solvent. And water itself participates in many chemical reactions.
Clam shells are made of calcium salts
Hemoglobin is found in erythrocytes - red blood cells
Starch accumulates in potato tubers
Water helps remove unnecessary and harmful substances from the body that are formed as a result of metabolism, and promotes the movement of oxygen, carbon dioxide and nutrients throughout the body.
Part of living organisms and mineral salts, however, in small quantities: they constitute up to 1% of the cell mass. The most common are sodium and potassium salts; they ensure the performance of such an important body function as irritability. Calcium salts give strength to bone tissue and the shells of numerous mollusks.
Organic substances are found only in living organisms. These are proteins, fats, carbohydrates, nucleic acids.
Squirrels- These are the main substances of the cell. If all the water is removed from a cell, then 50% of its dry mass will be proteins. These are very complex connections. The protein hemoglobin carries oxygen and is what gives blood its red color. Not a single movement associated with muscle contraction is carried out without contractile proteins. Proteins are also involved in protecting the body from infections, blood clotting and many other processes.
They also play an important role in the body carbohydrates. These are well-known glucose, sucrose (beet sugar that we eat every day), fiber, and starch. The main function of carbohydrates is energy. By “burning” glucose, the body receives the energy necessary for the processes taking place in it. Living organisms can store carbohydrates in the form of starch (plants) and glycogen (animals and fungi). In potato tubers, starch makes up up to 80% of the dry weight. Animals have a particularly high amount of carbohydrates in liver and muscle cells – up to 5%.
Carbohydrates also perform other functions, such as support and protection. Fiber is part of wood; chitin forms the exoskeleton of insects and crustaceans.
Fats perform a number of functions in the body. They provide the body with up to 30% of the energy it needs. In some animals, fats accumulate in large quantities and protect the body from heat loss.
Fats are also of great importance as an internal water reserve. As a result of the breakdown of fats in cells, up to 1.1 kg of water is formed from 1 kg of fat. This is very important for animals that hibernate in winter - gophers, marmots: thanks to their fat reserves, they can not drink for up to two months. When crossing the desert, camels go without drinking for up to two weeks: they extract the water necessary for the body from their humps, which are receptacles for fat.
Subcutaneous fat protects the seal's body from hypothermia
Nucleic acids(from the Latin “nucleus” - core) are responsible for the storage and transmission of hereditary characteristics from parents to offspring. They are part of chromosomes - special structures located in the cell nucleus.
Chromosomes transmit hereditary traits from parents to children
The distribution of substances and individual chemical elements in nature is heterogeneous.
Some organisms actively accumulate elements, for example, brown algae - iodine, buttercups - lithium, duckweed - radium, mollusks - copper.
The body of a jellyfish consists of 95% water, human brain cells - 85%, blood - 80%. In mammals, water loss exceeding 10% of body weight leads to death.
Hair, nails, claws, fur, feathers, and hooves consist almost entirely of protein. Snake venom is also protein.
In whales, the thickness of the subcutaneous fat layer reaches 1 m.
Brown algae fucus
Diagram of the occurrence of chemical elements on Earth
Solidified lava
Mineral crystals
Rock faults
Stalactite formations in a cave
Questions and tasks
1. List the elements that make up the basis of living organisms.
2. What substances are classified as inorganic? organic? Using the drawing, make pie charts of the content in the cell (in%) of inorganic and organic substances.
3. What is the function of water in a living organism?
4. Describe the importance of mineral salts in the body.
5. What is the role of proteins in the body?
6. Name the carbohydrates you know. Which of them are found in plant and which in animal organisms? Describe the significance of these organic substances.
7. Describe the role of fats in the body.
8. What organic substances of the cell ensure the storage and transmission of hereditary information? Where are they located in the cage?
9. Look at the diagrams. How does the chemical composition of living and nonliving bodies differ? Are there elements that are found only in living organisms?
10. What facts indicate the unity of origin of all living organisms?
Study of the chemical composition of seeds.
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Study the material and complete the assigned tasks.
The most common elements in living organisms are oxygen, carbon, nitrogen, and hydrogen. Living organisms include organic substances (proteins, fats, carbohydrates, nucleic acids) and inorganic substances (water, mineral salts).
7. Substances and phenomena in the surrounding world*
Substances
The world that surrounds a person is very diverse. You have studied the structure of the Solar System and know that it is made up of the Sun, planets, their satellites, asteroids, comets, and meteorites. They are all called bodies. While studying the structure of the Earth, you also become familiar with bodies - these are pieces of rocks and minerals. Plants, animals, humans are also bodies.
Everything that surrounds us - bodies of living and inanimate nature, products - consists of substances. Iron, glass, salt, water, polyethylene are substances. There are a lot of them. Currently, more than 7 million different substances are known, and every year people synthesize new, previously unknown ones. Scientists in many countries are working to create environmentally friendly automobile fuel, highly effective mineral fertilizers, medicines for influenza, AIDS and many other diseases.
In nature, substances exist in three states: solid, liquid and gaseous. Substances can change from one state to another.
In most cases, substances are found in the form mixtures. Sometimes this is clearly visible even to the naked eye. For example, looking at a piece of granite, you can see that it consists of a mixture of substances: quartz, mica and feldspar, but in homogeneous-looking milk, only under a microscope can you distinguish droplets of fat and proteins floating in the liquid (water).
Components of granite
Substances without impurities are called clean. Such substances do not exist in nature. Their production is one of the important tasks of the chemical industry. Pure substances are used in electronics, the nuclear industry, and in the production of medicines.
Impurities can dramatically change the properties of substances. A small addition of salt or sugar will change the taste of water, a drop of ink will change its color. This feature was noticed a very long time ago. Ancient metallurgists obtained alloys (mixtures of metals) - bronze, brass and others, which differed from the original metal, copper, in being more durable and resistant to water and air. When producing steel, a slight addition of the metal chromium makes it stainless, and the addition of tungsten gives it the ability to withstand very high temperatures.
In the mixture, each substance retains its properties. Knowing these properties, mixtures can be divided into their component parts.
Mixture separation
There are substances simple And complex. In order to answer the question of how they differ, you need to know the structural features of the substance. For centuries, scientists have been trying to find out how it works.
Models of molecules of simple and complex substances
It is now known that all substances consist of tiny particles: molecules, atoms or ions. They are so small that it is impossible to see them with the naked eye. Molecules are particles made up of atoms. Atoms of the same type are called elements. One molecule can have two, three, or even hundreds or thousands of atoms. Ions are modified atoms. In the future, you will learn about the structure of these particles in more detail.
By studying the structure of atoms, scientists have established that atoms differ from each other, that is, in nature there are different types of atoms: one type is oxygen atoms, the other is carbon atoms, etc. Modern science knows 111 types of atoms (elements). Combining with each other in various combinations, they form the variety of substances that exist in nature.
Now we can answer the question posed. If substances contain atoms of the same type, then such substances are called simple. These are metals that are well known to you (iron, copper, gold, silver) and non-metals (sulfur, phosphorus, graphite and many others).
Heating a mixture of iron and sulfur. Preparation of the complex substance iron sulfide. Iron + sulfur = iron sulfide
Liquid water
water vapor
Substances consisting of particles formed by atoms of different types are called complex. For example, water, carbon dioxide.
As a result of the reaction, a new complex substance can be obtained, for example iron sulfide. It does not contain simple substances - sulfur and iron. They are included in its composition as atoms of certain types (sulfur atoms and iron atoms).
Variety of natural phenomena
The world around us is constantly changing: water evaporates, snow melts, rocks are destroyed, wood burns, iron rusts, thunder rumbles, lightning flashes. Such changes are called phenomena. What do they have in common and how are they different? Let's do a little research.
You see that when heated, the shape of the body (a piece of ice) changed, but the composition of the substance (water) remained the same.
When a copper plate was heated, a new substance was formed - copper oxide.
The experiments carried out show that in some cases the formation of new substances occurs, in others – not. Based on this feature, physical and chemical phenomena are distinguished.
When water is heated, no new substances are formed
When a copper plate is heated, copper atoms interact with oxygen atoms, and a new substance is formed
TO physical include thermal, mechanical, light, sound, electrical and magnetic phenomena. We encounter them all the time in everyday life.
Iron rail joints
Phenomena associated with heating and cooling of bodies are called thermal.
When heated, the length and volume of bodies increase, and when cooled, they decrease. This phenomenon must be taken into account in construction and industrial production. When laying railway and tram tracks, small gaps are left at the joints of the rails, so that when the rail is heated and lengthened, the track is not destroyed. When building bridges, one end of the bridge is usually installed on special rollers. Thanks to this, the bridge does not collapse during thermal expansion or contraction.
Installation of a bridge on special rollers
Change in water condition
When the temperature changes, a substance can move from one state to another, which is clearly seen in the example of a change in the state of water.
An example of mechanical phenomena is a change in the shape of a body, such as the compression and expansion of a spring.
The movement of living organisms, celestial bodies, transport, rolling stones and snow from mountains, lifting and lowering loads, rotation of wheels - all movements of bodies in space are also mechanical phenomena.
Light phenomena are associated with the characteristics of the light beam. For example, the straightness of its propagation explains the formation of shadows.
Solar eclipse
The ability of light to reflect off the bodies on which it falls gives us the ability to see them.
Light phenomena in nature, such as rainbows, are amazingly beautiful. It is formed as a result of the decomposition of light in raindrops.
These are just some examples of physical phenomena. The main feature of all these phenomena is the preservation of substances.
Now let's consider chemical phenomena. In another way, these phenomena are called chemical transformations or chemical reactions. As a result of such reactions, new substances are formed that differ from the original ones in a number of ways.
Man uses chemical reactions to produce mineral fertilizers, medicines, paints, and detergents. Scientists create new substances that do not exist in nature.
Some chemical reactions occur very slowly, and we do not notice them; they last for billions of years. For example, a hard rock, limestone, is destroyed by water and carbon dioxide and transformed into other substances. Water washes them away - this is how voids and caves are formed in the mountains.
Other reactions occur very quickly (combustion, explosion). This is how fuel burns in a car engine or gas burner. When burning, a lot of heat and light are released.
Decomposition of light through a glass prism and a drop of water
Signs of chemical reactions
When dead parts of plants rot, heat is also released, but it is dissipated in the surrounding space. We usually do not notice this heat, but we must take it into account. An incorrectly folded haystack or poor straw storage conditions lead to the development of the rotting process. This can even cause spontaneous combustion of the material.
Questions and tasks
1. In what states can substances exist in nature?
2. Give examples of solid, liquid and gaseous mixtures. Name the most common gaseous mixture on the planet.
3. What substances are called pure?
4. Why does industrial production sometimes require the use of mixtures rather than pure substances?
5. How do complex substances differ from simple ones? Give examples of simple and complex substances.
6. Why are there many times more different substances in nature than there are types of atoms?
7. How do physical phenomena differ from chemical ones?
Laboratory and practical work
Description and comparison of characteristics of various substances. Observing signs of a chemical reaction. Study of some physical phenomena.
Refer to the electronic application
Study the material and complete the assigned tasks.
All bodies are made of substances. In nature, substances can be in solid, liquid and gaseous states. There are mixtures and pure substances, simple and complex substances.
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Question 1. What is the unit of structure of living beings? What is it called and who gave it that name?
The unit of structure, functioning and development of living beings is the cell. This name was given to it by the English naturalist and encyclopedist Robert Hooke (1635 - 1703).
Question 2. How long ago did people learn that the bodies of living beings consist of cells? Explain why this was not known before.
In 1665, examining the thinnest section of a cork under an improved three-lens microscope at 40x magnification, Robert Hooke discovered tiny cells, similar to the same cells in honey, and gave them the name “cells.” Also in 1665, Robert Hooke first reported the existence of cells.
Question 3. Are there cells that can be seen without a microscope? If yes, please provide examples.
Plant cells with large vacuoles: onions, oranges, pomelo. You can hold these large cells in your hands. There are also organisms belonging to the kingdom of fungi with giant multinucleate cells forming multinucleate schizonds.
Question 4. Look at the picture on page 108 of the textbook. Name the main parts of a living cell.
Each cell has three main parts: the outer membrane that covers the cell, the cytoplasm - a semi-liquid mass that makes up the main contents of the cell, and the nucleus - a small dense body located in the cytoplasm.
Question 5. What features of cells indicate that they are alive?
The cells are alive. They breathe, eat, grow and divide. One cell turns into two. Then from each new one, when it grows, two more. Thanks to this, the entire body grows and develops.
Question 6. The human body originates from a single cell, formed as a result of the fusion of two germ cells. An adult body consists of approximately 100 trillion cells. Where do so many cells come from?
Many cells appear due to the fact that the cells of the body are characterized by constant division through mitosis. From one cell two daughter cells are formed. At this rate, a large number of cells appear in the human body.
Question 7. Look at the picture of the cells of various parts of the animal. Why do you think there are so many types of cells in one organism? Try to tell by their appearance what kind of work they do.
There are often many types of cells in the body. They differ from each other in shape and size. For example, the cells that form muscles, bones, and the nervous system in the human body look completely different. There are also special cells - reproductive cells. They are different for men and women. The female reproductive cell is called the egg, and the male cells are called sperm. These cells give rise to a new organism; in other words, children are born thanks to them. For this to happen, the egg and sperm must unite. Their fusion is called fertilization. The fertilized egg divides many times, and an embryo develops from it.
Question 8: Explain why eggs are much larger than most other cells.
This one cell contains the basis for the development of absolutely all other cells, the whole organism, as well as the initial reserve for growth and nutrition. An example of this is not only the cells inside mammals, whose children develop and grow in the womb. But for example, the eggs of birds and amphibians are a real egg. Only developing outside the mother's body. That is, this one cell contains all the substances from which the rest will later be formed.
C3. What is the role of saliva in digestion? What reflexes provide salivation and under what conditions
Response elements:
1) saliva contains enzymes that break down starch, as well as substances that form a food bolus for swallowing;
2) unconditional reflex salivation occurs when receptors in the oral cavity are irritated;
3) conditioned reflex salivation occurs in response to stimulation of the visual, olfactory, and auditory analyzers
C1.
Response elements:
C3. Indicate which metabolic end products are formed in the human body and through which organs they are removed.
Response elements:
1) the end products of nitrogen metabolism (urea, uric acid), water, mineral salts are removed through the urinary organs;
2) water, mineral salts, and partially nitrogen metabolism products are removed through the sweat glands of the skin;
3) water vapor and carbon dioxide are removed by the respiratory system.
C1. Explain why mature red blood cells cannot synthesize proteins.
Response elements:
1) mature erythrocytes lack a nucleus where DNA molecules are located - carriers of hereditary information;
2) the absence of DNA makes it impossible to synthesize mRNA and tRNA, which are involved in protein synthesis
C2. Determine which bone is marked with an “X” in the picture. Indicate which part of the skeleton it belongs to? What is the role of this department?
Response elements:
1) bone - scapula;
2) is part of the shoulder girdle, or the girdle of the upper limbs;
3) creates support for the free upper limb and connects it to the body;
4) provides mobility of the upper limb
C4. In vertebrates, the organ of hearing changed during the process of evolution. In what sequence were its sections formed in vertebrates of various classes?
Response elements:
1) fish have an inner ear;
2) amphibians and reptiles have an inner and middle ear;
3) in mammals - inner, middle, outer ear.
C2. Look at the picture. Determine what is shown under the numbers 1 and 2? What role do these structures play in the joint? Explain your answer.
1) 1 - Articular capsule; 2 - articular surfaces covered with cartilage
2) The joint capsule provides strength to the joint and holds the bones
3) Articular surfaces provide bone sliding (mobility)
C2. Name the structures of the human heart, indicated by numbers. Indicate their functions.
Response elements: 
1) 1 - muscular wall of the ventricles, 2 - valves;
2) when the ventricular wall contracts, blood is pushed into the vessels of the circulatory system;
3) valves allow blood to flow in only one direction.
C3. Where is the center of unconditioned reflex regulation of pancreatic juice located and what is the humoral regulation of this process? What is the role of this juice in digestion?
Response elements:
1) the center is located in the medulla oblongata;
2) humoral regulation is determined by substances entering the blood during the breakdown of food;
3) pancreatic juice contains enzymes that break down proteins, lipids, and carbohydrates of food into their monomers, which can be absorbed by the cells of the body.
C2. What organ system do the human organs shown in the figure belong to? Name them, what role do they play in the body?
Response elements:
1) excretory system (urinary)
2) kidneys - filter the blood, remove harmful metabolic products from it, and participate in maintaining a constant composition of the internal environment
3) ureter - drains urine into the bladder
C3. What functions does each part of the human hearing organ perform?
Response elements:
1) the outer ear captures and directs sound;
2) the middle ear transmits and amplifies sound;
3) inner ear - auditory receptors are irritated and nerve impulses arise
C2. Name the chambers of the human heart, indicated in the figure by numbers 1 and 2. What kind of blood is contained in them and into which vessels does it enter during heart contraction?
Response elements:
1) 1 - right ventricle, venous blood;
2) blood enters the pulmonary artery;
3) 2 - left ventricle, arterial blood; 4) blood enters the aorta.
C2. Consider the cells of the human body shown in the figure, numbered 1 and 2. Determine what types of tissues they belong to. As a result, cells with the same genotype acquire different specializations during the formation of an organism?
Response elements:
1) 1 - epithelial;
2) 2 - smooth muscle;
3) during the formation of tissues, cell specialization occurs. In them, with the same genotypes, different genes are active, so the cells are different in structure and functions
C3. Name at least three functions performed by the skeleton of terrestrial vertebrates.
Response elements:
1) protects internal organs from damage;
2) performs the functions of support and movement;
3) participates in hematopoiesis and metabolism.
C1. People of many professions stand motionless on their feet throughout the working day, so they often develop an occupational disease - dilation of the veins of the lower extremities. Explain why this is happening.
Response elements:
1) when standing for a long time, the outflow of blood from the veins is disrupted;
2) there is no contraction of the muscles of the lower extremities, which contribute to the contraction of the walls of the veins and the movement of blood upward
C2. Determine which bone in the picture is indicated by the sign “?”. Indicate, indicate which part of the skeleton it belongs to? List the meanings of this skeletal region.
Response elements:
1) bone - clavicle;
2) upper limb girdle or shoulder girdle;
3) creates support for the upper limbs, connects the upper limbs and the torso;
4) provides mobility of the free upper limb.
C3. Where are the centers of food regulation of gastric juice located in the human body? How is unconditioned reflex and conditioned reflex regulation of digestive processes carried out?
Response elements:
1) the unconditioned reflex center is located in the medulla oblongata. Conditioned reflex - in KBP GM
2) the unconditioned reflex center ensures the separation of gastric juice when food enters the oral cavity and stomach
3) Conditioned reflex secretion of gastric juice occurs at the sight, smell, or thought of food
GENERAL BIOLOGY Part C
C2. What is the name of the series of ancestors of the modern horse presented in the figure? What changes have occurred in the horse's limb? Specify at least three signs
Response elements:
1) the evolutionary series of the ancestors of the modern horse is called a phylogenetic series;
2) lengthening of limbs;
3) reducing the number of fingers to one;
4) hoof formation.
C4. Why is the expansion of a species' range considered a sign of biological progress? Provide 3 pieces of evidence.
Response elements:
1) the diversity of environmental conditions ensuring the reproduction and development of individuals of the species increases;
2) food opportunities are expanding and the food supply is improving;
3) intraspecific competition weakens.
C2. A comparative study of pancreatic and skeletal muscle cells revealed a difference in the percentage of Golgi apparatus structures. Explain these differences in terms of its function.
Response elements:
1) the Golgi apparatus accumulates products synthesized in the cell, packages them and ensures excretion;
2) in the cells of the pancreas, unlike skeletal muscle cells, digestive juice and hormones are synthesized and secreted, therefore the percentage of the Golgi apparatus is higher in them.
C4. What changes in structure and life activity accompanied the evolution of reptiles during their exploration of land? Please provide at least three changes.
Response elements:
1) dry, keratinized skin without glands, preventing water loss;
2) reproduction is not associated with water (internal fertilization, development of the embryo in an egg with dense egg membranes);
3) progressive development of the respiratory, excretory and circulatory organs.
C1. Explain why a feeling of pain occurs in the muscle cells of an untrained person after strenuous physical work.
Response elements:
1) during intense physical work, a lack of oxygen occurs in muscle tissue cells;
2) glycolysis occurs, as a result of which lactic acid accumulates, which causes these symptoms.
C3. By what structural features can you distinguish a bacterial cell from a plant cell? Name at least three signs
Response elements:
1) the bacterial cell lacks a formed nucleus;
2) the genetic material of a bacterial cell is represented by a circular DNA molecule;
3) bacterial cells lack membrane organelles
C4. How did the emergence of photosynthetic organisms influence the further evolution of life on Earth?
Response elements:
Photosynthetic organisms provided:
1) transformation of solar energy, synthesis of organic substances from inorganic substances, nutrition of heterotrophs;
2) the accumulation of oxygen in the atmosphere, which contributed to the emergence of the oxygen type of metabolism;
3) the appearance of the ozone layer, which protects organisms from ultraviolet radiation, which ensured that organisms reached land.
C1. In the 18th century, the English scientist D. Priestley conducted an experiment. He took two identical glass covers. He placed a mouse under the first cap, and a mouse with a houseplant under the second. Explain why after some time the first mouse under the glass bell died, while the second continued to live.
Response elements:
1) the first mouse died due to lack of oxygen and excess carbon dioxide released during respiration;
2) the houseplant, during the process of photosynthesis, absorbed carbon dioxide and released oxygen necessary for the respiration of both organisms, so the second mouse continued to live.
C4. What adaptations have developed in plants during the process of evolution due to their widespread distribution on land? Give at least three examples.
Response elements:
1) tissue differentiation: mechanical, conductive, integumentary;
2) the appearance of vegetative organs that provide vital functions;
3) independence of the process of sexual reproduction from water.
C1. Explain why mature red blood cells cannot synthesize proteins.
Response elements:
1) mature erythrocytes lack a nucleus where DNA molecules are located - carriers of hereditary information;
2) the absence of DNA makes it impossible to synthesize mRNA and tRNA, which are involved in the synthesis of proteins.
C3. By what characteristics do higher seed plants differ from lower plants? Give at least three signs.
Response elements:
1) the presence of various tissues, the development of vegetative and generative organs;
2) propagation by seeds, independence of fertilization from the presence of water;
3) the predominance of the sporophyte (asexual generation) over the gametophyte (sexual generation) in the development cycle.
C4. What is the role of the driving forces of evolution in shaping the fitness of organisms according to Darwin's teachings?
Response elements:
1) due to hereditary variability, the population becomes heterogeneous and new characteristics arise;
2) as a result of the struggle for existence, organisms with these characteristics are selected;
3) natural selection preserves individuals with useful hereditary changes, ensuring the formation of adaptability to certain conditions.
C1. Biological oxidation in the human body is similar in chemical process to the combustion of fuel (coal, peat, wood). What substances are oxidized in the human body and what products common to combustion are formed as a result of these processes?
Response elements:
1) in the human body, organic substances (proteins, fats, carbohydrates) undergo biological oxidation;
2) as a result of their oxidation, as during combustion, carbon dioxide and water are formed.
C1. An amateur gardener sowed a self-pollinating heterozygous variety of cucumbers and reaped a very high harvest. The next year, when sowing from seeds taken from the resulting harvest, he harvested significantly less, although he grew the plants under the same conditions. Explain why.
Response elements:
1) new heterozygous varieties are hybrids with a heterotic effect;
2) when heterotic forms are sown, the characteristics are split, the proportion of heterozygotes is reduced, and the proportion of homozygotes increases, therefore the total mass of the harvested crop decreases;
Response elements:
2) they are characterized by a high degree of adaptability to living in the bodies of various organisms (hooks, suckers, resistance to digestion);
3) their large numbers are due to the level of fertility;
4) wide distribution is ensured by the migration of host organisms.
C4. What social factors of anthropogenesis contributed to human evolution? Name at least 3 factors.
Response Elements:
1) work activity;
2) social way of life, using the experience of previous generations;
3) development of speech, abstract thinking, and the emergence of writing.
C4. Explain why in nature, stagnant fresh water bodies often turn into swamps.
Response elements:
1) due to a lack of oxygen, some of the dead plants settle to the bottom without rotting;
2) reservoirs gradually become shallow due to the accumulation of dead plants, and aquatic vegetation moves to the center of the reservoirs;
3) the combination of rich organic matter from dead plants and shallowing leads to an increase in semi-aquatic vegetation, and waterlogging occurs.
C4. Reveal the role of plants in history. Give at least four meanings.
Response elements:
1) ensured the transformation of solar energy, the creation of organic substances and the nutrition of heterotrophic organisms;
2) ensured the accumulation of oxygen in the atmosphere and the appearance of aerobic organisms;
3) contributed to the formation of the ozone layer, which ensured the access of organisms to land;
4) participated in the formation of soil, peat, minerals, and perform an environment-forming function.
C1. People with sickle cell disease produce abnormal hemoglobin, which leads to the production of altered red blood cells. What type of mutations are we talking about? Justify your answer.
Response elements:
1) sickle cell anemia is caused by a gene mutation;
2) there is a change in the sequence of amino acids in hemoglobin, which is associated with a violation of the structure of the gene encoding the primary structure of the hemoglobin molecule.
C4. In the process of evolution, organisms have developed various adaptations to their environment. What is their significance and how does the relative nature of fitness manifest itself? Explain your answer with an example.
Response elements:
1) fitness helps an organism to survive in the conditions in which it was formed under the influence of the driving forces of evolution;
2) any trait of fitness is useful for an organism to live in certain conditions, but in changed conditions fitness becomes useless and even harmful - this shows the relative nature of fitness;
3) any example (seasonal changes in the color of the white hare).
C1. Why is natural selection not eliminating all harmful gene mutations? What is the significance of these mutations for evolution?
Response elements:
1) many gene mutations are recessive and remain in the gene pool of populations in heterozygous organisms;
2) when environmental conditions change, some previously harmful recessive mutations may turn out to be useful, and their carriers will gain an advantage in the struggle for existence, as a result of which a new species may form.
C1. What global changes on the planet could mass destruction of forests lead to? Give at least three examples.
Response elements:
1) to changes in air composition, carbon dioxide and oxygen content in the atmosphere, the greenhouse effect;
2) to a decrease in biodiversity;
3) changes in the water regime of the soil lead to erosion, drying out and desertification.
C4. In the open spaces of the steppes and prairies of different continents in the past, herds of different types of herbivores grazed: bison, antelope, wild aurochs, wild horses. What reasons have led to the decline in numbers and complete extinction of some species to date?
Response elements:
1) natural spaces of steppes and prairies were transformed into agricultural land
2) the reduction of natural habitats has led to a sharp decline in the number of wild animals
3) some of the animals were destroyed by hunting
C1 What environmental consequences can forest fires lead to in Russia?
Response elements:
1) complete disappearance of some species of plants and animals;
2) changes in the structure of the biocenosis, disruption of the appearance of the landscape.
C4. In some years, outbreaks of insect pests are observed in nature. What biotic factors can reduce their numbers? Give at least 3 factors.
Response elements:
1) Increase in the number of insectivorous birds;
3) intraspecific and interspecific competition for food and shelter.
1 . How is the energy of sunlight converted in the light and dark phases of photosynthesis into the energy of chemical bonds of glucose? Explain your answer.
1) the energy of sunlight is converted into the energy of excited electrons of chlorophyll;
2) the energy of excited electrons is converted into the energy of high-energy bonds of ATP, the synthesis of which occurs in the light phase (part of the energy is used for the formation of NADP-2H);
3) in the reactions of the dark phase, the energy of ATP is converted into the energy of chemical bonds of glucose, which is synthesized in the dark phase.
2 . It is known that all types of RNA are synthesized on a DNA template. The fragment of the DNA molecule on which the region of the central loop of tRNA is synthesized has the following nucleotide sequence: ACGCCCGCTAATTCAT. Establish the nucleotide sequence of the tRNA region that is synthesized on this fragment and the amino acid that this tRNA will carry during protein biosynthesis if the third triplet corresponds to the tRNA anticodon. Explain your answer. To solve the task, use the genetic code table.
The problem solution scheme includes:
1) nucleotide sequence of the tRNA region UGCGTCGAUUAAGUA;
2) the nucleotide sequence of the GAU anticodon (third triplet) corresponds to the codon on the CUA mRNA;
3) according to the table of the genetic code, this codon corresponds to the amino acid Leu, which this tRNA will carry.
3 . The chromosome set of somatic wheat cells is 28. Determine the chromosome set and the number of DNA molecules in one of the ovule cells before the onset of meiosis, in anaphase of meiosis I and anaphase of meiosis II. Explain what processes occur during these periods and how they affect changes in the number of DNA and chromosomes.
The problem solution scheme includes:
2) in anaphase of meiosis I, the number of DNA molecules is 56, the number of chromosomes is 28, homologous chromosomes diverge to the poles of the cell;
3) in anaphase of meiosis II, the number of DNA molecules is 28, chromosomes - 28, sister chromatids - chromosomes - diverge to the poles of the cell, since after the reduction division of meiosis I the number of chromosomes and DNA decreased by 2 times
4. It is known that all types of RNA are synthesized on a DNA template. The fragment of the DNA strand on which the central loop of tRNA is synthesized has the following nucleotide sequence: ACGGTAATTGCTATC. Establish the nucleotide sequence of the tRNA region that is synthesized on this fragment and the amino acid that this tRNA will carry during protein biosynthesis if the third triplet corresponds to the tRNA anticodon. Explain your answer. To solve the task, use the genetic code table.
The problem solution scheme includes:
1) nucleotide sequence of the tRNA region: UGCCAUAAATCGAUAG;
2) the nucleotide sequence of the UAA anticodon (third triplet) corresponds to the codon on the AYU mRNA;
3) according to the table of the genetic code, this codon corresponds to the amino acid Ile, which this tRNA will carry.
5. It is known that all types of RNA are synthesized on a DNA template. The fragment of the DNA molecule on which the region of the central loop of tRNA is synthesized has the following nucleotide sequence: ACGGTAAAAGCTATC. Establish the nucleotide sequence of the tRNA region that is synthesized on this fragment and the amino acid that this tRNA will carry during protein biosynthesis if the third triplet corresponds to the tRNA anticodon. Explain your answer. To solve the task, use the genetic code table.
The problem solution scheme includes:
1) nucleotide sequence of the tRNA region: UGCCAUUUCGAUAG;
2) the nucleotide sequence of the anticodon UUU (third triplet) corresponds to the codon on the AAA mRNA;
3) according to the table of the genetic code, this codon corresponds to the amino acid Lys, which this tRNA will carry.
6. It is known that all types of RNA are synthesized on a DNA template. The fragment of the DNA chain on which the central loop of tRNA is synthesized has the following nucleotide sequence: TGCCCATTTCGTTACG. Establish the nucleotide sequence of the tRNA region that is synthesized on this fragment and the amino acid that this tRNA will carry during protein biosynthesis if the third triplet corresponds to the tRNA anticodon. Explain your answer. To solve the task, use the genetic code table.
The problem solution scheme includes:
1) nucleotide sequence of the tRNA region - ACGGGGUAAGCAAUGC;
2) the nucleotide sequence of the AAG anticodon (third triplet) corresponds to the codon on the UUC mRNA;
3) according to the table of the genetic code, this codon corresponds to the amino acid Phen, which this tRNA will carry
7. The chromosome set of somatic wheat cells is 28. Determine the chromosome set and the number of DNA molecules in the cells of the root tip before the start of mitosis, in metaphase and at the end of telophase. Explain what processes occur during these periods and how they affect the change in the number of DNA molecules and chromosomes.
The problem solution scheme includes:
1) before the start of mitosis, the number of DNA molecules is 56, because they double, but the number of chromosomes does not change - 28;
2) in the metaphase of mitosis, the number of DNA is 56, chromosomes are 28, the chromosomes are located in the equatorial plane, the spindle threads are connected to the centromeres;
3) at the end of the telophase of mitosis, 2 nuclei are formed, in each nucleus the number of DNA is 28, chromosomes - 28. Then 2 cells are formed with a set of chromosomes identical to the original mother cell;
8. What chromosome set is characteristic of the cells of leaves, spores, and fern shoots? Explain how the set of chromosomes is formed in each case.
The problem solution scheme includes:
1) in the cells of a fern leaf there is a diploid set of chromosomes 2n, because an adult fern plant is a sporophyte and develops from a fertilized egg;
2) in a fern spore the haploid set of chromosomes is n, because spores are formed as a result of meiosis, so the set of chromosomes is 2 times smaller;
3) in the cells of the germ the haploid set of chromosomes is n, because the prothallus develops from a haploid spore.
9 . Chromosome set of somatic cells of wheat 28. Determine the chromosome set and the number of DNA molecules in the cells of the root tip before the start of mitosis, in anaphase and at the end of the telophase of mitosis. Explain what processes occur during these phases and how they affect the change in the number of DNA molecules and chromosomes.
The problem solution scheme includes:
1) before the start of mitosis, the number of DNA molecules is 56, because they double. But the number of chromosomes does not change - 28.
2) In anaphase of mitosis, the number of DNA molecules is 56, chromosomes are 56. Sister chromosomes diverge to the poles of the cell, so the total number of chromosomes in the cell increases by 2 times
3) at the end of the telophase of mitosis, 2 nuclei are formed, the number of DNA molecules is 28, chromosomes are 28, then 2 cells are formed with a set of chromosomes identical to the mother cell
10 . The chromosome set of somatic wheat cells is 28. Determine the chromosome set and the number of DNA molecules in the ovule cells before the onset of meiosis, in metaphase of meiosis I and metaphase of meiosis II. Explain what processes occur during these periods and how they affect changes in the number of DNA and chromosomes.
The problem solution scheme includes:
1) before the start of meiosis, the number of DNA molecules is 56, since they double, but the number of chromosomes does not change - there are 28 of them;
2) in metaphase of meiosis I, the number of DNA molecules is 56, the number of chromosomes is 28, homologous chromosomes are located in pairs above and below the equatorial plane, the spindle is formed;
3) in metaphase of meiosis II, the number of DNA molecules is 28, chromosomes - 14, since after the reduction division of meiosis I the number of chromosomes and DNA decreased by 2 times, the chromosomes are located in the equatorial plane, the division spindle is formed.
11. It is known that all types of RNA are synthesized on a DNA template. The DNA fragment on which the region of the central loop of tRNA is synthesized has the following nucleotide sequence: ACG-CGA-CGT-GGT-CGA Establish the nucleotide sequence of the tRNA region that is synthesized on this fragment, and the amino acid that this tRNA carries in the process of protein biosynthesis, if the third triplet corresponds to the tRNA anticodon. Explain your answer.
The problem solution scheme includes:
1) nucleotide sequence of the tRNA region: UGC-GCU-GCA-CCA-GCU;
2) the nucleotide sequence of the anticodon - GCA (third triplet) corresponds to the codon on the CGU mRNA;
3) according to the table of the genetic code, this codon corresponds to the amino acid Apr, which this tRNA will carry.
12. The chromosome set of somatic wheat cells is 28. Determine the chromosome set and the number of DNA molecules in the ovule cells before the onset of meiosis, at the end of the prophase of meiosis I and at the end of the telophase of meiosis I. Explain what processes occur during these periods and how they affect the change in the number of DNA and chromosomes.
The problem solution scheme includes:
1) before the start of meiosis, the number of DNA molecules is 56, since they double, but the number of chromosomes does not change - there are 28 of them;
2) in prophase of meiosis I, the number of DNA molecules is 56, the number of chromosomes is 28, chromosomes are spiralized, homologous chromosomes are connected in pairs and form bivalents, conjugation and crossing over occur;
3) in the telophase of meiosis I, the number of DNA molecules is 28, the number of chromosomes is 14, reduction division occurs, 2 cells with a haploid set of chromosomes are formed, each chromosome consists of two sister chromatids.
13 . What chromosome set is characteristic of the leaves of the cuckoo flax moss plant, its gametes and sporogon (pods on a stalk). Explain the result in each case
The problem solution scheme includes:
1) in leaves - a haploid set of chromosomes - n, because an adult plant develops from a haploid spore;
2) gametes are haploid - n, because develop on an adult plant by mitosis;
3) sporogon - diploid - 2n, because develops from a zygote.
1. In maize, the recessive gene “shortened internodes” (b) is located on the same chromosome with the recessive gene “incipient panicle” (v). When conducting an analytical cross with a plant that had normal internodes and a normal panicle, all the offspring were similar to one of the parents.
When the resulting hybrids were crossed with each other, the offspring turned out to be 75% of plants with normal internodes and normal panicles, and 25% of plants with shortened internodes and a rudimentary panicle. Determine the genotypes of parents and offspring in two crosses. Make a diagram for solving the problem. Explain your results. What law of heredity is manifested in the second case?
The problem solution scheme includes:
1) first crossing parent genotypes: norm: BBVV x bbvv;
Gametes:BV bv;
Offspring: BbVv;
2) second crossing of parental genotypes: BbVv x BbVv;
Gametes: BV, bv BV, bv;
Offspring: 75% BBVV and BbVv, 25% bbvv.
3) genes are linked, crossing over does not occur. Morgan's law of linked inheritance of traits appears.
2. In sheep, gray wool color (A) dominates over black, and horned (B) dominates over polled (hornless) hair. The genes are not linked. In the homozygous state, the gray color gene causes the death of embryos. What viable offspring (by phenotype and genotype) and in what ratio can be expected from crossing a diheterozygous sheep with a heterozygous gray polled male? Make a diagram for solving the problem. Explain your results. What law of heredity is manifested in this case?
The problem solution scheme includes:
1) genotypes of the parents: P female - AaBb x male - Aabb;
Gametes G AB, Ab, aB, ab Ab, ab
2) offspring: F 1: 2 gray horned - AaBb, 2 gray polled - Aabb, 1 black horned - aaBb, 1 black polled - aabb;
3) homozygous gray polled sheep AAbb, AAB are absent in the offspring as a result of embryo death. Mendel's law of independent inheritance of traits appears.
3 . Blood type and Rh factor are autosomal unlinked traits. Blood type is controlled by three alleles of one gene - i°, I A, I B. Alleles I A and I B are dominant to the i° allele. The first group (0) is determined by recessive genes i°, the second group (A) is determined by the dominant allele I A, the third group (B) is determined by the dominant allele I B, and the fourth (AB) is determined by two dominant alleles I A I B. Positive Rh factor R dominates negative r.
The father has the first blood group and is Rh negative, the mother has the second blood group and is Rh positive (diheterozygote). Determine the genotypes of the parents, possible genotypes and phenotypes of the children, their blood groups and Rh factor. Make a diagram for solving the problem. What law of heredity is manifested in this case?
The problem solution scheme includes:
1) genotypes of the parents: mother - I A i°Rr, father - i°i°rr;
Gametes I A R, I A r, i°R, i°r, i°r;
2) offspring: second group, Rh positive - I A i°Rr; second group Rh negative - I A i°rr; the first group is Rh positive - i°i°Rr; first group Rh negative i°i°rr;
4. In sheep, gray wool color (A) dominates over black, and horned (B) dominates over polled (hornless) hair. The genes are not linked. In the homozygous state, the gray color gene causes the death of embryos. What viable offspring (by phenotype and genotype) and in what ratio can be expected from crossing a diheterozygous sheep with a black horned (homozygous) male? Make a diagram for solving the problem. What law of heredity is manifested in this case?
The problem solution scheme includes:
1) genotypes of the parents: P female - AaBb x male - aaBB;
Gametes G AB, Ab, aB, ab aB
2) offspring F 1: gray horned - AaBB, AaB, black horned - aaBB, aaB;
3) Mendel’s law of independent inheritance of traits is manifested.
5. In sheep, the gray color (A) of wool dominates over black, and hornedness (B) dominates over polled (hornless). The genes are not linked. In the homozygous state, the gray color gene causes the death of embryos. What viable offspring (by phenotype and genotype) and in what ratio can be expected from crossing a diheterozygous sheep with a gray horned male homozygous for the second trait? Make a diagram for solving the problem. Explain your results. What law of heredity is manifested in this case?
The problem solution scheme includes:
1) genotypes of the parents: P female-AaBb x male-AaBB;
Gametes G AB, Ab, aB, ab AB, aB
2) offspring of Fi: gray horned - AaBB, AaB, black horned - aaBB, aaB;
3) homozygous gray horned AABB, AAB are absent as a result of embryo death. Mendel's law of independent inheritance of traits appears.
6 . In canaries, the sex-linked gene X B determines the green color of the feathers, X b - brown. In birds, the homogametic sex is male, the heterogametic sex is female, and the presence of a crest is a dominant autosomal trait (A). A green crested male was crossed with a brown female without a crest. The offspring were tufted green, tufted brown, tuftless green and tuftless brown. Draw up a scheme for solving the problem, determine the genotypes of parents and offspring, their corresponding phenotypes, and determine the possible sex of the offspring. What laws of heredity are manifested in this case?
The problem solution scheme includes:
1) R: ? aa X b Y x? Aa X B X b
G: a X b ; a U AX B; A X b;a X B; a X b
2) Genotypes and phenotypes of offspring:
Aa X B X b - green crested;
Aa X b X b - brown crested;
aa X B X b - green without tuft;
aa X b X b - brown without tuft;
Aa X V U - green crested;
Aa X b U - brown crested;
aa X V U - green without a tuft;
aa X b U - brown without a tuft.
3) the law of independent inheritance and inheritance of sex-linked characteristics is manifested
7 . In canaries, the sex-linked gene X B determines the green color of the feathers, X b - brown. In birds, the homogametic sex is male, the heterogametic sex is female, and the presence of a crest is a dominant autosomal trait (A). A tufted brown male was crossed with a green female without a tuft. In the offspring, all females with a crest and without a crest were brown, and all males with a crest and without a crest were green. Determine the genotypes of parents and offspring corresponding to their phenotypes, what laws of inheritance are manifested. Make a diagram for solving the problem.
The problem solution scheme includes:
1) P: ааХ В У x АаХ b Х b
G: aX Bipsup> aU AX b aX b
2) F 1: АаХ В Х b - ? tufted green
aaХ B X b - green without crest;
АаХ В У - tufted brown;
aaХ V U - brown without crest.
3) the law of independent inheritance of traits and sex-linked inheritance is manifested
8. In canaries, the sex-linked gene X B determines the green color of the feathers, X b - brown. In birds, the homogametic sex is male, the heterogametic sex is female, and the presence of a crest is a dominant autosomal trait (A). A tufted brown male was crossed with a green female without a tuft. All offspring turned out to be crested, but all females are brown and males are green. Determine the genotypes of parents and offspring that correspond to their phenotypes. What patterns of inheritance appear in this case. Make a diagram for solving the problem.
The problem solution scheme includes:
1) P: aaХ B U x AAX b X b
G: aX B; аУ АХ b
2) F 1 АаХ В Х b - tufted green
АаХ b У - tufted brown
3) the laws of independent inheritance of traits and sex-linked inheritance of traits are manifested
9 . Based on the pedigree shown in the figure, determine and explain the nature of inheritance of the trait highlighted in black. Determine the genotypes of the parents, offspring 1,6, 7 and explain the formation of their genotypes.
The problem solution scheme includes:
2) genotypes of the parents: father - X a Y, mother - X A X A, daughter 1 - X A X a is the carrier of the gene, since she inherits the X a chromosome from her father;
3) children: daughter 6 X A X A or X A X a, son 7 X a Y, the trait appeared because we inherit the X a chromosome from the mother.
10. In dogs, black hair is dominant over brown hair, and long hair is dominant over short hair (the genes are not linked). The following offspring were obtained from a black long-haired female through analytical crossing: 3 black short-haired puppies, 3 black long-haired puppies. Determine the genotypes of parents and offspring that correspond to their phenotypes. Make a diagram for solving the problem. Explain your results.
1) genotypes of the parents: P female - AABb x male - aabb;
Gametes G AB, Ab, ab;
2) offspring F 1: black shorthaired - Aabb, black longhaired - AaBb;
3) if, during an analyzing dihybrid cross, 2 phenotypic groups appear in the offspring in a 1:1 ratio, then the female with the dominant phenotype is heterozygous for hair length.
11. In canaries, the sex-linked gene X B determines the green color of the plumage, and X b - brown. In birds, the homogametic sex is male, and the heterogametic sex is female. The presence of a crest is a dominant autosomal trait of A. A green crested male was crossed with a brown female without a crest. All the offspring turned out to be crested, but half had green and half had brown plumage. Make a diagram for solving the problem. Determine the genotypes of parents and offspring corresponding to their phenotypes, and the possible sex of the offspring. What laws of heredity are manifested in this case?
The problem solution scheme includes:
1) genotypes of the parents: P female aaX b Y x male AAX B X b
Gametes aX b aY AX B AX b
2) genotypes of offspring F 1:
Males: tufted green AaX B X b; tufted brown AaX b X b ;
Females are crested green AaH V U; tufted brown - АаХ b У.
3) independent inheritance of traits and sex-linked traits.
12. Based on the pedigree shown in the figure, determine and explain the nature of inheritance of the trait highlighted in black. Determine the genotypes of parents 3,4, offspring 8,11. And explain the formation of their genotypes.
The problem solution scheme includes:
1) the trait is recessive, linked to sex (X chromosome), since it appears only in men and not in every generation;
2) genotypes of the parents: father - X A Y, because the sign is absent; mother 3 - X A X a is a carrier of the gene, because inherits the X a chromosome from his father,
3) children: son 8 - X and U, because inherits chromosome Xa from mother 3; daughter 11 X A X a is a carrier of the gene, because inherits chromosome X A from mother and X a from father
13. In dogs, black coat color dominates over brown, long hair over short hair. From a black short-haired female and a brown long-haired male, 1 black short-haired puppy was born. 1 brown long-haired puppy. Determine the genotypes of parents and offspring corresponding to the phenotypes. What law of heredity is manifested?
The problem solution scheme includes:
1) P Aabb x aaBb
Gametes Ab ab aB ab
Black longhaired AaBb;
Black shorthair AAbb;
Brown longhaired aaBb;
Brown shorthair aabb;
3) The law of independent inheritance appears.
14. A woman with straight hair without freckles has both parents with curly hair and freckles. The genes are not linked. Her husband is diheterozygous for these characteristics. Determine the genotypes of the woman, her husband, possible genotypes and phenotypes of their children. What law of heredity is manifested in this case? Make a crossbreeding diagram.
The problem solution scheme includes:
1) P: aabb x AaBb
Gametes ab AB Ab aB ab
2) Possible offspring
AaBb - curly with freckles;
Aabb - curly without freckles;
aaBb - straight hair with freckles;
aabb - straight hair without freckles.
3) the law of independent inheritance of characteristics is manifested.
This happened more than 300 years ago. The English scientist Robert Hooke examined under a microscope a thin section of a bottle cap made from the bark of a cork oak tree. What Hooke saw was a great discovery. He discovered that cork was made up of many small cavities, chambers, which he called cells. It was soon discovered that other parts of plants also consist of cells. Moreover, it was discovered that the bodies of animals and humans are built from cells.
If we could shrink ourselves a million times, amazing possibilities would open up for us. We could go inside cells and explore them the way travelers explore mysterious jungles, caves, or the depths of the sea. If we were tireless and visited the inside of a variety of organisms, we would be able to find out the following.
Microscope by R. Hooke. Section of a cork under a microscope
This is what a modern microscope looks like
No matter how diverse the living creatures that inhabit our planet are, they all have a cellular structure. The body of a plant, an animal, a person is built of cells, like a house of bricks. Therefore, cells are often called the “building blocks” of the body. But this is a very, very rough comparison.
Firstly, the cells are complex, not like bricks fashioned from clay. Each cell has three main parts: outer membrane who dresses the cage, cytoplasm- a semi-liquid mass that constitutes the main contents of the cell, and core- a small dense body located in the cytoplasm.
Secondly, our “building blocks” are alive. They breathe, they eat, they grow... and they divide. One cell turns into two. Then from each new one, when it grows, two more. Thanks to this, the entire body grows and develops.
And finally, thirdly, in the body there are most often many types of cells. They differ from each other in shape and size. For example, the cells that form muscles, bones, and the nervous system in the human body look completely different. There are also special cells - sexual. They are different for men and women. The female reproductive cell is called egg, and male cells - spermatozoa. These cells give rise to a new organism; in other words, children are born thanks to them. For this to happen, the egg and sperm must unite. Their merger is called fertilization. The fertilized egg divides many times and develops into an embryo. Human development in the mother's body lasts 9 months. When a child is born, it is difficult to believe that only two small cells gave him life - the mother's egg and the father's sperm.
There are approximately 200 types of cells in the human body. And their total number is about 100 trillion. This number is written like this: 100,000,000,000,000.
Big world of small cells
We already know that the body of any plant, animal, or human has organs. The cell also has “organs”. They are located in the cytoplasm and are called organoids, i.e. “organ-like”. You can see some of them in the picture. Mitochondria are responsible for cell respiration, lysosomes are responsible for digestion. And the network of tubes resembles blood vessels - through them different substances pass from one part of the cell to another.
Almost all cells are very small. You can't see them without a microscope. And you have all seen the chicken egg more than once: this is the yolk of the egg. Huge cage! It is even greater in an ostrich egg: after all, about 30 chicken eggs could fit in it.
The eggs of fish and frogs - eggs - are much smaller than those of birds. But they are also much larger than most other cells.
The eggs are so large because they contain a large supply of nutrients necessary for the development of the embryo.
Many plant cells contain special green organelles - chloroplasts(from the Greek word "chloros" - green). They give the plant its green color. Chloroplasts are very important for plants: it is in them that nutrients are formed in the light.
Test your knowledge
- How were the cells discovered?
- Why are cells called the “building blocks” of the body?
- Name the main parts of a living cell.
- What features of cells indicate that they are alive?
- What cells give rise to a new organism? How does this happen?
- What is shown in these pictures?
Think!
- Using your observations and pictures from the textbook, talk about the diversity of cells.
- Consider the cells of different parts of the plant and the human body in the picture. Why do you think there are so many types of cells in one organism? Try to tell by their appearance what kind of work they do.
- Explain the meaning of the words: cell, outer membrane of the cell, cytoplasm, cell nucleus, germ cells, egg, sperm, fertilization.
Living things have a cellular structure. The main parts of a cell are the outer membrane, cytoplasm and nucleus. Living cells breathe, eat, grow, and divide. They are varied in shape and size. Among them are germ cells that give rise to a new organism.
1. What is the unit of structure of living beings? What is it called and who gave it that name?
The cell is the structural unit of living things.
cell theory was developed by German scientists T. Schwann and M. Schleiden.
2. How long ago did people learn that the bodies of living beings consist of cells? Explain why this was not known before?
In 1665, examining the thinnest section of a cork under an improved three-lens microscope at 40x magnification, Robert Hooke discovered tiny cells, similar to the same cells in honey, and gave them the name “cells.” Also in 1665, Robert Hooke first reported the existence of cells.
3. Are there cells that can be seen without a microscope? If yes, please provide examples.
Plant cells with large vacuoles: onions, oranges, pamella. You can hold these large cells in your hands. There are also organisms belonging to the kingdom of fungi with giant multinucleate cells forming multinucleate schizonds.
4. Look at the picture on p. 30 textbook. Name the main parts of a living cell.
Parts of the cell: cytoplasm (semi-liquid substance); nucleus (storage and transmission of hereditary information); nuclear envelope - separates the nucleus from the cytoplasm; ribosomes - protein synthesis; mitochondria (energy is produced; cell center - cell division.
5. What features of cells indicate that they are alive?
Cells breathe, grow, eat, divide.
6. The human body originates from a single cell, formed as a result of the fusion of two germ cells. An adult body consists of approximately 100 trillion cells. Where do so many cells come from?
Many cells appear due to the fact that the cells of the body are characterized by constant division through mitosis. From one cell two daughter cells are formed. At this rate, a large number of cells appear in the human body.
7. In the picture, look at the cells of different parts of the plant and the human body. Why do you think there are so many types of cells in one organism? Try to tell by their appearance what kind of work they do.
Each group of cells in the body performs a specific function (nutrition, respiration, reproduction, etc.), because There are many processes in the body necessary for normal functioning; one cell could not cope with them, therefore the cells in the body are distributed according to the functions they perform.
Human cells: multinucleated cells - will be cells of striated muscle tissue; colorless cells with an amoeba-like shape - leukocytes, whose function is photosynthesis; red anucleate cells - erythrocytes (carriers of oxygen and carbon dioxide).
Plant cells: small, colorless, tightly adjacent cells - these are skin cells; green bean-shaped cells - guard cells of the stomata; green cells are cells that carry out photosynthesis.
8.* Explain why the egg is much larger than most other cells.
This one cell contains the basis for the development of absolutely all other cells, the whole organism, as well as the initial reserve for growth and nutrition. An example of this is not only the cells inside mammals, whose children develop and grow in the womb. But for example, the eggs of birds and amphibians are a real egg. Only developing outside the mother's body. That is, this one cell contains all the substances from which the rest will later be formed.