Reproduction. A cow and a calf, a horse and a foal, an oak tree and an oak tree, a hen and chickens are just a few examples of adult organisms and their young. Pay attention to the accuracy with which the offspring inherit the structure and behavior of their parents. The property of organisms to produce offspring that has the characteristics of parents is called reproduction (Fig. 117). This property of organisms ensures the continuity of life on Earth.
The ability of organisms to reproduce like themselves is called breeding.
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| Rice. 118. Development of wheat |
Growth and development. A grain of wheat, planted in the spring in the soil, gives rise to a small sprout. Gradually, leaves appear on it, the stalk thickens, and after a few months the sprout becomes an adult plant with an ear.
Mice are born naked, toothless, and after two months they become adults. As you can see, in both examples, the size and mass of organisms increased, that is, growth occurred. In the process of growth of a sprout of a plant and mice, not only the mass and size of organisms changed - new formations arose: leaves and an ear - in wheat (Fig. 118), fur and teeth - in mice (Fig. 119). Such gradual changes in organisms are called development.
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| Rice. 119. Development of mice |
Growth - a gradual increase in the size, weight of the body.
Development - changes in the structure of the body and its individual parts.
Nutrition and respiration. Organisms need food.
Nutrition It is the process of absorption of nutrients in the body.
In the process of nutrition, organisms receive a variety of organic and inorganic substances that ensure their growth, development and other life processes. material from the site
The substances necessary for life in the body come from the external environment. "Extra" substances, such as carbon dioxide, undigested food residues, are excreted into the external environment.
Organisms have respiration. Most organisms breathe oxygen, which is part of the air. In cells between oxygen and organic substances are constantly undergoing various chemical phenomena. In this case, energy is released, which organisms use for growth, development, movement.
Irritability. Organisms are capable of responding to environmental influences. This is called irritability. For example, in bright light, we squint our eyes or cover them with our palms; the hedgehog curls up into a ball when touched; the hare runs away, noticing the approach of a predator.
Irritability is the ability of an organism to respond to changes in environmental conditions.
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Plants, like all living organisms, constantly breathe (aerobes). To do this, they need oxygen. It is needed by both unicellular and multicellular plants. Oxygen is involved in the vital processes of cells, tissues and organs of a plant.
Most plants obtain oxygen from the air through stomata and lenticels. Aquatic plants consume it from the water with the entire surface of the body. Some plants growing in wetlands have special respiratory roots that absorb oxygen from the air.
Respiration is a complex process that takes place in the cells of a living organism, during which, during the decay of organic substances, the energy necessary for the vital processes of the organism is released. The main organic matter involved in the respiratory process are carbohydrates, mainly sugars (especially glucose). The intensity of respiration in plants depends on the amount of carbohydrates accumulated by shoots in the light.
The entire process of respiration takes place in the cells of the plant organism. It consists of two stages, during which complex organic substances are split into simpler, inorganic ones - carbon dioxide and water. At the first stage, with the participation of special proteins that accelerate the process (enzymes), the breakdown of glucose molecules occurs. As a result, simpler organic compounds are formed from glucose and little energy (2 ATP) is released. This stage of the respiratory process occurs in the cytoplasm.
At the second stage, simple organic substances formed at the first stage, interacting with oxygen, are oxidized - they form carbon dioxide and water. This releases a lot of energy (38 ATP). The second stage of the respiratory process proceeds only with the participation of oxygen in special cell organelles - mitochondria.
Respiration is the process of decomposition of organic nutrients to inorganic substances (carbon dioxide and water) with the participation of oxygen, accompanied by the release of energy, which is used by the plant for life processes.
C 6 H 12 O 6 + 6 O 2 \u003d 6CO 2 + 6 H 2 O + Energy (38 ATP)
Respiration is a process opposite to photosynthesis
| Photosynthesis | Breath |
| 1. Absorption of carbon dioxide 2. Release of oxygen. 3. The formation of complex organic substances (mainly sugars) from simple inorganic ones. 4. Water absorption. 5. Absorption of solar energy with the help of chlorophyll and its accumulation in organic substances. b. It only happens in the world. 7. Occurs in chloroplasts. 8. Occurs only in the green parts of the plant, mainly in the leaf. | 1. Absorption of oxygen. 2. Emission of carbon dioxide. 3. The splitting of complex organic substances (mainly sugars) into simple inorganic ones. 4. Water release. 5. Release of chemical energy during the oxidation of organic substances 6. Occurs continuously in the light and in the dark. 7. Occurs in the cytoplasm and mitochondria. 8. Occurs in the cells of all plant organs (green and non-green) |
The process of respiration is associated with the continuous consumption of oxygen day and night. The process of respiration is especially intensive in young tissues and organs of the plant. The intensity of respiration is determined by the needs of plant growth and development. A lot of oxygen is required in the areas of cell division and growth. The formation of flowers and fruits, as well as damage and especially tearing off of organs, is accompanied by an increase in respiration in plants. At the end of growth, with yellowing of the leaves and, especially in winter, the intensity of respiration decreases markedly, but does not stop.
Breathing, like nutrition, is a necessary condition for metabolism, and hence for the life of the organism.
Ø C1. In small rooms with an abundance of indoor plants, oxygen concentration decreases at night. Explain why. 1) at night, with the cessation of photosynthesis, the release of oxygen ceases; 2) in the process of plant respiration (they breathe constantly), the concentration of O 2 decreases and the concentration of CO 2 increases
Ø C1. It is known that experimentally it is difficult to detect the respiration of plants in the light. Explain why.
1) in the light in the plant, along with respiration, photosynthesis occurs, in which carbon dioxide is used; 2) as a result of photosynthesis, oxygen is produced much more than is used in the respiration of plants.
Ø C1. Why can't plants live without respiration? 1) in the process of respiration, plant cells absorb oxygen, which breaks down complex organic substances (carbohydrates, fats, proteins) to less complex ones; 2) this releases energy that is stored in ATP and used for life processes: nutrition, growth, development, reproduction and etc.
Ø C4. The gas composition of the atmosphere is maintained at a relatively constant level. Explain what role organisms play in this. 1) photosynthesis, respiration, fermentation regulate the concentration of O2, CO2; 2) transpiration, sweating, respiration regulate the concentration of water vapor; 3) the vital activity of some bacteria regulates the content of nitrogen in the atmosphere.
The importance of water in the life of plants
Water is essential for the life of any plant. It makes up 70-95% of the wet body weight of the plant. In plants, all life processes proceed with the use of water.
Metabolism in a plant organism occurs only with a sufficient amount of water. Mineral salts from the soil enter the plant with water. It provides a continuous flow of nutrients through the conductive system. Without water, seeds cannot germinate; there will be no photosynthesis in green leaves. Water in the form of solutions that fill the cells and tissues of the plant, provides it with elasticity, maintaining a certain shape.
- The absorption of water from the external environment is a prerequisite for the existence of a plant organism.
The plant receives water mainly from the soil through the root hairs of the root. The above-ground parts of the plant, mainly the leaves, evaporate a significant amount of water through the stomata. These moisture losses are replenished regularly as the roots constantly absorb water.
It happens that during the hot hours of the day, the consumption of water by evaporation exceeds its intake. Then the leaves of the plant wither, especially the lowest ones. During the night hours, when the roots continue to absorb water, and the evaporation of the plant is reduced, the water content in the cells is restored again and the cells and organs of the plant again acquire an elastic state. When transplanting seedlings, the lower leaves are removed to reduce water evaporation.
The main way water enters living cells is its osmotic absorption. Osmosis - this is the ability of the solvent (water) to enter the cell solutions. In this case, the flow of water leads to an increase in the volume of fluid in the cell. The force of osmotic absorption with which water enters the cell is called sucking force .
The absorption of water from the soil and its loss through evaporation create a permanent water exchange at the plant. Water exchange is carried out with the flow of water through all organs of the plant.
It consists of three stages:
absorption of water by the roots,
its movement through the vessels of wood,
evaporation of water from leaves.
Usually, with normal water exchange, as much water enters the plant, so much of it evaporates.
The water current in the plant goes in an upward direction: from the bottom up. It depends on the strength of water absorption by the root hair cells at the bottom and on the intensity of evaporation at the top.
Root pressure is the bottom mover of water current
the sucking force of leaves - top.
The constant flow of water from the root system to the aerial parts of the plant serves as a means of transporting and accumulating in the organs of the body of mineral substances and various chemical compounds coming from the roots. It unites all the organs of the plant into a single whole. In addition, the upward flow of water in the plant is necessary for the normal water supply of all cells. It is especially important for the implementation of the process of photosynthesis in the leaves.
ü C1. Plants absorb a significant amount of water during their life. What are the two main processes
most of the water consumed is consumed by life activities? Explain the answer. 1) evaporation, which ensures the movement of water and dissolved substances and protection against overheating; 2) photosynthesis, during which org in-va are formed and oxygen is released
The abundance or deficiency of moisture in the cells affects all vital processes of the plant.
In relation to water, plants are divided into environmental groups
Ø Hydatophytes(from Greek. hydatos- "water", fiton- "plant") - water grasses (elodea, lotus, water lilies). Hydatophytes are completely submerged in water. The stems have almost no mechanical tissues and are supported by water. In plant tissues there are many large intercellular spaces filled with air.
Ø hydrophytes(from Greek g idros- “water”) - plants partially submerged in water (arrowhead, reed, cattail, reed, calamus). They usually live along the banks of reservoirs in damp meadows.
Ø Hygrophytes(from Greek. gigra- "moisture") - plants of humid places with high air humidity (marigold, sedges). 1) plants of wet habitats; 2) large bare leaves; 3) stomata do not close; 4) have special aquatic stomata - hydotodes; 5) there are few vessels.
Ø Mesophytes(from the Greek mezos - “middle”) - plants living in conditions of moderate moisture and good mineral nutrition (leaf grass, lily of the valley, strawberries, apple trees, spruce, oak). Grow in forests, meadows, fields. Most agricultural plants are mesophytes. They develop better with additional watering. 1) plants of sufficient moisture; 2) grow mainly in meadows and forests; 3) the growing season is short, no more than 6 weeks; 4) dry time is experienced in the form of seeds or bulbs, tubers, rhizomes.
Ø Xerophytes(from Greek. xeros- "dry") - plants of dry habitats, where there is little water in the soil, and the air is dry (aloe, cacti, saxaul). Among xerophytes, dry and juicy are distinguished. Juicy xerophytes with fleshy leaves (aloe, crassula) or fleshy stems (cacti - prickly pear) are called succulents. Dry xerophytes - sclerophytes(from the Greek scleros - “hard”) are adapted to austerity of water, to a decrease in evaporation (feather grass, saxaul, camel thorn). 1) plants of dry habitats; 2) able to tolerate lack of moisture; 3) the surface of the leaves is reduced; 4) leaf pubescence is very abundant; 5) have deep root systems.
Leaf modifications
arose in the process of evolution due to the influence of the environment, so they sometimes do not look like an ordinary leaf.
· spines in cacti, barberry, etc. - adaptations to reduce the area of evaporation and a kind of protection from being eaten by animals.
· tendrils in peas, ranks attach a climbing stem to a support.
· Juicy bulb scales, the leaves of a head of cabbage store nutrients,
· 
Covering scales of the kidneys- modified leaves that protect the bud of the shoot.
In insectivorous plants ( sundew, pemphigus etc.) leaves - trapping devices. Insectivorous plants grow on soils poor in minerals, especially with insufficient nitrogen, phosphorus, potassium and sulfur. From the bodies of insects, these plants receive inorganic substances.
leaf fall is a natural and physiologically necessary phenomenon. Thanks to leaf fall, plants protect themselves from death during an unfavorable season - winter - or a dry period in a hot climate.
ü Dropping leaves that have a huge evaporating surface, plants seem to balance the possible arrival and the necessary water consumption for the specified period.
ü Dropping leaves, plants are freed from various waste products accumulated in them produced during metabolism.
ü Leaf fall protects the branches from breaking off under the pressure of snow masses.
But some flowering plants have leaves that last all winter. These are evergreen shrubs of lingonberries, heather, cranberries. The small dense leaves of these plants, which slightly evaporate water, are preserved under the snow. Winter with green leaves and many herbs, such as strawberries, clover, celandine.
Calling some plants evergreen, we must remember that the leaves of these plants are not eternal. They live for several years and gradually fall off. But new leaves grow on new shoots of these plants.
Plant reproduction. Reproduction is a process that leads to an increase in the number of individuals.
In flowering plants, there are
Ø vegetative reproduction, in which the formation of new individuals occurs from the cells of vegetative organs,
Ø seed reproduction, in which the formation of a new organism occurs from a zygote that arises from the fusion of germ cells, which is preceded by a number of complex processes that occur mainly in flowers.
Reproduction of plants with the help of vegetative organs is called vegetative.
Vegetative propagation, carried out with human intervention, is called artificial. Artificial vegetative propagation of flowering plants is resorted to in the event that
§ if the plant does not produce seeds
§ accelerate flowering and fruiting.
Under natural conditions and in culture, plants often reproduce by the same organs. Very often, reproduction occurs with the help of Cherenkov. A cutting is a segment of any vegetative plant organ capable of restoring missing organs. Segments of a shoot with 1-3 leaves, in the axils of which axillary buds develop, are called stem cuttings . Under natural conditions, willows, poplars easily propagate with such cuttings, and in culture - geraniums, currants ...
reproduction leaves occurs less frequently, but occurs in plants such as meadow core. On moist soil at the base of a broken leaf, an adnexal bud develops, from which a new plant grows. The leaves propagate the Uzambara violet, some types of begonias and other plants.
On the leaves of bryophyllum are formed baby kidneys, which, falling to the ground, take root and give rise to new plants.
Many types of onions, lilies, daffodils, tulips breed bulbs. At the bulb, a fibrous root system originates from the bottom, and young bulbs, called kids. From each baby bulb, a new adult plant grows over time. Small bulbs can form not only underground, but also in the axils of the leaves of some lilies. Falling to the ground, such baby bulbs also develop into a new plant.
Plants are easily propagated by special creeping shoots - mustache(strawberry, creeping tenacious).
Reproduction by division:
§ bushes(lilac) when the plant reaches a considerable size, it can be divided into several parts;
§ rhizomes(irises) each segment taken for propagation must have either an axillary or apical bud
§ tubers(potato, Jerusalem artichoke) when there are not enough of them for planting in a certain area, especially if it is a valuable variety. The division of the tuber is carried out so that each part has an eye and that the supply of nutrients is sufficient to reproduce a new plant;
§ roots(raspberries, horseradish) which, under favorable conditions, give new plants;
§ root cones - tuber roots, which differ from the real root in that they do not have nodes and internodes. The buds are located only on the root collar or stem end, therefore, in dahlias, tuberous begonias, the root neck is divided with tuberous root formations.
Reproduction by layering. When propagated by layering, the shoot not separated from the mother plant is bent to the soil, the bark is cut under the kidney and sprinkled with earth. When roots appear at the incision site and above-ground shoots develop, the young plant is separated from the mother plant and transplanted. Layering can propagate currants, gooseberries and other plants.
Graft.
A special method of vegetative propagation is grafting. Grafting is the transplantation of a part of a living plant, equipped with a bud, to another plant with which the first is crossed. The plant that is grafted onto is called rootstock; plant that is grafted scion.
In grafted plants, the scion does not form roots and feeds on the stock, while the stock receives from the scion organic substances synthesized in its leaves. Vaccinations are most often used to propagate fruit trees, which are difficult to form adventitious roots and cannot be bred in any other way. Grafting can also be done by transplanting a piece of stem with one bud under the bark of the scion ( budding ) and crossing scion and stock of the same thickness ( copulation ). When grafting, it is necessary to take into account the age and position of the cutting on the mother plant, as well as the characteristics of the scion. Thus, various methods of vegetative propagation show that in many plants a whole organism can be restored from a part.
The relationship of organs. Despite the fact that all organs of a plant have a structure inherent only to them and perform specific functions, thanks to the conducting system they are connected together, and the plant functions as a complex integral organism. Violation of the integrity of any organ necessarily affects the structure and development of other organs, and this influence can be both positive and negative. For example, the removal of the top of the stem and root contributes to the intensive development of the aboveground and underground parts of the plant, and the removal of leaves retards growth and development and may even lead to its death. Violation of the structure of any organ entails a violation of its functions, which affects the functioning of the whole plant.
1. Plant nutrition
Plant nutrition can be mineral and air. Air nutrition is photosynthesis, and mineral nutrition is the absorption of water and minerals dissolved in it from the soil by root hairs. The predominant components are nitrogen, potassium and phosphorus. Nitrogen ensures the rapid growth of plants, phosphorus - the ripening of fruits, and potassium - the rapid outflow of organic matter from the leaves to the roots. Lack or excess of mineral nutrition leads to plant diseases.
Photosynthesis is the creation of organic substances from inorganic substances using light energy. In this process, the leading organ is the leaf of the plant. The structure of the leaf is well suited to this function: it has a flat leaf blade, and the pulp of the leaf contains a huge amount of chloroplasts with green chlorophyll.
Experience 1. Formation of organic substances in leaves
Purpose: to find out in which cells of a green leaf organic substances (starch, sugar) are formed.
What we do: let's place a houseplant bordered geranium for three days in a dark closet (so that there is an outflow of nutrients from the leaves). After three days, take the plant out of the closet. We attach a black paper envelope with the word “light” cut out to one of the leaves and put the plant in the light or under an electric light bulb. After 8-10 hours, cut the leaf. Let's take off the paper. We lower the leaf into boiling water, and then for a few minutes into hot alcohol (chlorophyll dissolves well in it). When the alcohol turns green and the leaf becomes discolored, rinse it with water and place it in a weak solution of iodine.
What we observe: blue letters will appear on a discolored sheet (starch turns blue from iodine). The letters appear on the part of the sheet on which the light fell. This means that starch has formed in the illuminated part of the leaf. It is necessary to pay attention to the fact that the white strip along the edge of the sheet is not colored. This explains the fact that there is no chlorophyll in the plastids of the cells of the white stripe of the bordered geranium leaf. Therefore, starch is not detected.
Conclusion: thus, organic substances (starch, sugar) are formed only in cells with chloroplasts, and light is necessary for their formation.
Special studies of scientists have shown that sugar is formed in chloroplasts in the light. Then, as a result of transformations from sugar, starch is formed in chloroplasts. Starch is an organic substance that does not dissolve in water.
The process of photosynthesis can be represented as a summary equation:
6CO2 + 6H2O = C6H12O6 + 6O2
Thus, the essence of light reactions is that light energy is converted into chemical energy.
Formation of organic substances.
The starch formed in chloroplasts, under the influence of special substances, turns into soluble sugar, which enters the tissues of all organs of the plant. In the cells of some tissues, sugar can again turn into starch. Spare starch accumulates in colorless plastids.
From the sugars formed during photosynthesis, as well as the mineral salts absorbed by the roots from the soil, the plant creates the substances that it needs: proteins, fats and many other proteins, fats and many others.
Part of the organic substances synthesized in the leaves is spent on the growth and nutrition of the plant. The other part is kept in reserve. In annual plants, reserve substances are deposited in seeds and fruits. In biennials in the first year of life, they accumulate in the vegetative organs. In perennial grasses, substances are stored in underground organs, and in trees and shrubs - in the core, the main tissue of the bark and wood. In addition, at a certain year of life, organic substances also begin to be stored in fruits and seeds.
2. Plant respiration and gas exchange
In the living cells of a plant, there is a constant exchange of substances and energy.
Leaves, thanks to the work of stomata, carry out such an important function as gas exchange between the plant and the atmosphere. Through the stomata of the leaf with atmospheric air, carbon dioxide and oxygen enter. Oxygen is used for respiration, carbon dioxide is necessary for the plant to form organic substances. Through the stomata, oxygen is released into the air, which was formed during photosynthesis. Carbon dioxide, which appeared in the plant in the process of respiration, is also removed. Photosynthesis is carried out only in the light, and respiration in the light and in the dark, i.e. constantly. Respiration in all living cells of plant organs occurs continuously. Like animals, plants die when they stop breathing.
In nature, there is an exchange of substances between a living organism and the environment. The absorption of certain substances by the plant from the external environment is accompanied by the release of others.
Experience 2. Plant respiration
Elodea, being an aquatic plant, uses carbon dioxide dissolved in water for nutrition.
Purpose: to find out what substance releases Elodea into the external environment during photosynthesis?
What we do: cut the stems of the branches under water (boiled water) at the base and cover with a glass funnel. A test tube filled to the brim with water is placed on the funnel tube. Do this in two ways. Put one container in a dark place, and put the other in bright sunlight or artificial light
Add carbon dioxide to the third and fourth containers (add a small amount of baking soda or you can breathe into a tube) and also put one in the dark and the other in sunlight.
What we observe: after some time, in the fourth variant (a vessel standing in bright sunlight), bubbles begin to stand out. This gas displaces water from the test tube, its level in the test tube is displaced.
What we do: when the water is completely displaced by the gas, you must carefully remove the test tube from the funnel. Close the hole tightly with the thumb of the left hand, and quickly insert a smoldering splinter into the test tube with the right.
What we observe: the splinter lights up with a bright flame. Looking at the plants that were placed in the dark, we will see that no gas bubbles are released from the elodea, and the test tube remains filled with water. The same with test tags in the first and second versions.
Conclusion: it follows that the gas that the elodea released is oxygen. Thus, the plant releases oxygen only when there are all conditions for photosynthesis - water, carbon dioxide, light.
When breathing, organic substances are consumed - their decomposition, i.e. oxidation, combination with oxygen. This process takes place in all living cells of the plant and is accompanied by the release of energy - heat. Therefore, all parts of the plant breathe. In the process of photosynthesis, plants emit oxygen 10-20 times more than they absorb it during respiration.
Photosynthesis and respiration proceed through numerous successive chemical reactions in which one substance is converted into another.
So, in the process of photosynthesis from carbon dioxide and water received by the plant from the environment, sugars are formed, which are then converted into starch, fiber or proteins, fats and vitamins - substances that the plant needs for nutrition and energy storage. In the process of respiration, on the contrary, the organic substances created in the process of photosynthesis are split into inorganic compounds - carbon dioxide and water. In this case, the plant receives the released energy. These transformations of substances in the body are called metabolism. Metabolism is one of the most important signs of life: with the cessation of metabolism, the life of a plant ceases.
3. Transpiration
Plants are 80% water. The process of evaporation of water from leaves in plants (transpiration) is regulated by the opening and closing of stomata. By closing the stomata, the plant protects itself from water loss. The opening and closing of stomata is influenced by external and internal factors, primarily temperature and sunlight intensity.
Plant leaves contain a lot of water. It enters through the conducting system from the roots. Inside the leaf, water moves along the cell walls and along the intercellular spaces to the stomata, through which it leaves in the form of steam (evaporates). This process is easy to check if you perform a simple experiment.
Experience 3. Transpiration
Let us place a leaf of a plant in a glass flask, isolating it from the environment. After some time, the walls of the flask will be covered with droplets of water. This proves the process of transpiration.
Water evaporates from the surface of the plant leaf. There are cuticular transpiration (evaporation by the entire surface of the plant) and stomatal (evaporation through the stomata). The biological significance of transpiration is that it is a means of moving water and various substances around the plant (suction action), promotes the entry of carbon dioxide into the leaf, carbon nutrition of plants, and protects the leaves from overheating.
The rate of evaporation of water by leaves depends on:
biological characteristics of plants;
Growth conditions (plants in arid areas evaporate little water, wet ones - much more; shady plants evaporate less water than light ones; plants evaporate a lot of water in heat, much less in cloudy weather);
Lighting (scattered light reduces transpiration by 30-40%);
Osmotic pressure of cell sap;
Soil, air and plant body temperatures;
Humidity and wind speed.
The greatest amount of water evaporates in some species of tree species through leaf scars (the scar left by fallen leaves on the stem), which are the most vulnerable places on the tree.
Different plants evaporate different amounts of water. So, corn evaporates 0.8 liters of water per day, cabbage - 1 liter, oak - 50 liters, birch - more than 60 liters. Forests of various tree species evaporate water during the summer from 1 ha: spruce forest - 2240 tons, beech - 2070 tons, oak - 1200 tons, pine - 470 tons.
Under different conditions, plants evaporate water in different ways. In cloudy weather, evaporation is less than on a sunny day, and in windy weather it is more than on a quiet day. Transpiration protects plants from overheating, because. energy is absorbed during the evaporation process. The larger the leaf blade, the larger its surface and the more intense the evaporation process.
4. Plant propagation
Sexual reproduction of angiosperms is associated with a flower. Its most important parts are stamens and pistils. They undergo complex processes associated with sexual reproduction.
Pollen grains are formed in the anthers of the stamens. The outer shell, as a rule, is uneven, with spines, warts, outgrowths in the form of a mesh. The pollen grain falls on the stigma of the pistil and is attached to it due to the structural features of the shell, as well as the sticky sugary secretions of the stigma, to which the pollen sticks. The pollen grain swells and germinates into a long, very thin pollen tube. The pollen tube is formed as a result of division of a vegetative cell. First, this tube grows between the cells of the stigma, then the style, and finally grows into the cavity of the ovary.
The generative cell of the pollen grain moves into the pollen tube, divides and forms two male gametes (sperms). When the pollen tube enters the embryo sac through the pollen passage, one of the sperm fuses with the egg. Fertilization occurs and a zygote is formed.
The second sperm fuses with the nucleus of a large central cell of the embryo sac. Thus, in flowering plants, two fusions occur during fertilization: the first sperm fuses with the egg, the second with a large central cell. Double fertilization is typical only for flowering plants.
The zygote formed by the fusion of gametes divides into two cells. Each of the resulting cells divides again, and so on. As a result of multiple cell divisions, a multicellular embryo of a new plant develops.
The central cell also divides, forming endosperm cells, in which nutrient reserves accumulate. They are necessary for the nutrition and development of the embryo. The seed coat develops from the integument of the ovule. After fertilization, a seed develops from the ovule, consisting of a skin, an embryo, and a supply of nutrients.
After fertilization, nutrients flow to the ovary, and it gradually turns into a ripe fruit. The pericarp, which protects the seeds from adverse effects, develops from the walls of the ovary. In some plants, other parts of the flower also take part in the formation of the fruit.
The main method of propagation of flowering plants is by seeds. But there is also vegetative propagation.
Vegetative reproduction is reproduction by the vegetative organs of plants - roots, shoots or parts thereof. It is based on the ability of plants to regenerate, to restore the whole organism from a part. Strengthening the function of vegetative reproduction has led to a significant modification of the organs.
Specialized shoots of vegetative propagation are aboveground and underground stolons, rhizomes, tubers, bulbs, etc.
1. Propagation by cuttings (aerial shoots). The most common method of propagating indoor plants at home is cuttings.
Cuttings when propagated by cuttings can act as stems, stem pieces, leaves.
Stem cuttings propagate most indoor plants.
To do this, choose a healthy non-flowering shoot. They cut off a cutting from 7-15 cm long from it (it all depends on the length of the stem), cut the shoot below the node with a blade or a sharp knife, cut off the leaves from the bottom of the cutting, prepare a phytohormone solution and lower the lower part of the shoot there for a few seconds, do a recess in the soil with a pencil and place a shoot there, the soil around is crushed with a pencil.
2. Mustache reproduction. The appearance of small daughter plants at the ends of some flowering plants indicates that the time has come for reproduction.
To do this, it is enough to dig the daughter plant into the soil, and after rooting, separate it from the mother plant. If the daughter plant has its own roots, then it can be immediately separated from the mother and planted as a rooted cutting.
3. Reproduction by root offspring
4. Reproduction by layering. Propagation by layering is very suitable for plants with long stems (these are climbing plants). To do this, just choose a strong shoot and press it to the soil with a piece of wire.
This procedure should be carried out in spring or summer. As soon as the shoot takes root and young shoots go from it, the plant can be separated.
5. Dividing the bush. Plants that form shoots can be propagated by dividing the bush.
6. Leaf reproduction. Reproduction by leaf is carried out in such indoor plants as jade, echeveria, stonecrop. For this, leaf cuttings are used: they take a large fleshy leaf, which is planted in the soil, the top layer of which is covered with coarse sand. A small leaf is simply laid flat on the soil and slightly pressed down, and a large leaf is simply dipped into the soil with its lower part. Royal begonia, Mason's begonia propagate with the help of a part of the leaf.
7. Underground shoots (rhizome, tuber, bulb)
8. Propagation by grafting consists in transferring parts of one plant to another and splicing them together. Thus, the varietal features of the grafted plant are preserved. Roses, lilacs, aza-leas, cacti are propagated by grafting.
Help solve the problem
If a stone fell from a mountain and split, then this stone is an object of what nature?
Why? After all, there was one stone, there were many.
There are no signs of wildlife.
Yes guys. Stone is the body of nature. Bodies in nature can change.
Is flowing water in a river an object of wildlife? No.
But the water in the river is moving, isn't it?
Water moves because the earth is round.
Attention game "What is superfluous?" Why didn't you name the houses, the cars? (Answers of children). That's right, because all this is created by man, not nature.
Conversation: A tree is an object of wildlife, but a log? An object of inanimate nature.
Why? Is it possible to call a spoon, a table, a house objects of nature? No.
And where did people get the material to make these items? From nature.
Conclusion: Man, for his own good, takes both from animate and inanimate nature.
Inanimate - sand - glass, tap water.
Conclusion: these are just objects that a person made from objects of nature, for his own convenience.
Fizminutka: The wind blows in our faces
The tree swayed.
The wind is quieter, quieter, quieter
The tree is getting higher and higher.”
– About what living the object of nature we spoke? - About the tree.
- Prove that the tree belongs to living nature.
- It has all the signs of living nature. It is born (a sprout appears), grows, breathes, feeds, multiplies, dies.
On the example of plants, we will consider how a living organism develops. Let's start with what plants are. (Structure of the plant.) -root - the main organ of the plant.
Explain diagram: seed - root - sprout - plant - bud - flower - fruit - seed.
Do all plants reproduce by seed? (potato, strawberry, tulip).
Using the potato as an example, consider all seasonal changes
Guys, where do you need to plant a sprout so that it can grow ? (into the soil)
What is soil? (the land where the plants grow from). Why?
Nutrients.
What is needed for plant growth. Air, sun and water.
And why do living beings need air, including us.
How do plants breathe?
And without air, all living things cannot do.
You said that the plant needs light. Where do they get it from? (The sun)
Why do they need light? What happens if the sun disappears? (Without sunlight and heat, most animals, plants, and man himself cannot exist.)
What is water for? (Answers of children). to live
How does a plant drink water from the ground?
Imagine for a moment that inanimate nature, namely the sun, air, water, will disappear. Will plants, animals and man himself be able to exist then.
Conclusion: Living and non-living nature are interconnected.
Psycho-gymnastics "I am a plant."
“Imagine you are baby plants. You were planted in black, which means fertile land. You are still small sprouts, very weak, fragile, defenseless. But someone's good hands are watering you, wiping the dust, loosening the earth so that your roots breathe. You start growing. Your petals have grown, the stem is growing stronger, you are reaching for the light. It is so good for you to live together with other beautiful flowers.”
In nature, there are 4 seasons.
There are natural phenomena in nature
Solving riddles.
1. Without arms, without legs, but opens the gate. /Wind/.(air movement)
2. Mochit grove, forest and meadow. City, house and everything around! Clouds and clouds - he is the leader, You know, this is ...
(this is not just water, but a real miracle created by nature itself!)
3. Red yoke, hung across the river. /Rainbow/. ( the sun plays with water droplets).
1. The wind plays with leaves, Breaks them from the trees.
Everywhere the leaves are circling - This means .... (leaf fall)
2. Hot arrow, oak fell near the village. /Lightning/.
Thunderstorm - stormy weather with rain, thunder and lightning. Thunderstorms are associated with the development of cumulonimbus clouds, with the accumulation of a large amount of electricity in them. Multiple electrical discharges occurring in clouds or between clouds and the ground are called lightning. A beautiful, but at the same time, frightening natural phenomenon.
There are many natural phenomena in nature.
Conclusion: Nature is very beautiful and defenseless.
We, unfortunately, often hurt her.
And only a man can save her.
How can one save her?
Nature must be respected
She is our mother to all of us.
She takes care of us.
Always saves in difficult times.
We must all keep it
Protect, love and do not forget
Yes, do not forget in an unkind hour
That we only have one.
Our mission is to love and protect nature.
Subject: Movement speed.
Target: Development of creative abilities. Cultivate attention, speed of reaction, dexterity, develop correct posture. Improving the motor skills of children in jumping on two legs moving forward and crawling on all fours. - teach children to throw sandbags at a horizontal target
Guys, today we will go to the Zoo. Stand one behind the other forward step march.
We get up early in the morning
Loudly call the watchman
Watchman, watchman quickly
Come out to wake the animals.
Walking normal
The ponies woke up first
Walking on toes with high knees
Walking normal
Get ready to run - run, and ponies run so high raising their knees.
Run normal
Running with high knees
Walking is normal, building in links
General developmental exercises:
"Giraffe" head tilts
arms down along the body
1 - raise your head up
2 - lower
arms down along the body
Raise your hands up stretch, lower your hands, return vi.p.
"Tilts and Turns"
feet shoulder width apart, arms along the body. Lean forward to reach the tips of the toes with your hands, straighten up, turn to the right, the same to the left.
4. "Squat"
feet shoulder width apart, hands on the belt. Sit down, bring your hands forward, get up, return vi.p.
lying on your back, arms along the body. Pull your knees up to your chest, clasp them with your hands. Return vi.p.
6. lying on your back, hands behind your head - alternately raise your left, then your right legs, return to ip.
7. Jumping "Hares" (alternating with walking).
legs together, arms bent at the elbows at the chest.
8. Breathing exercise
Main part.
1. Crawling on the gymnastic bench, leaning on the forearm and knees
2. Jumping on two legs moving forward
3. Throwing sandbags at a horizontal target.
Night falls, the whole zoo falls asleep, only one owl does not sleep at this time of the day, she loves to play and we will play "Owl" with you. Outdoor game "Day-night"
Final part:
Walking normal
Low mobility game "Find and keep silent"
Amphibians(they are amphibians) - the first terrestrial vertebrates that appeared in the process of evolution. At the same time, they still retain a close relationship with the aquatic environment, usually living in it at the larval stage. Typical representatives of amphibians are frogs, toads, newts, salamanders. The most diverse in tropical forests, as it is warm and damp there. There are no marine species among amphibians.
Representative of amphibians - red-eyed tree frogGeneral characteristics of amphibians
Amphibians are a small group of animals with about 5,000 species (according to other sources, about 3,000). They are divided into three groups: Tailed, Tailless, Legless. The frogs and toads familiar to us belong to the tailless ones, the newts belong to the tailed ones.
Amphibians have paired five-fingered limbs, which are polynomial levers. The forelimb consists of the shoulder, forearm, hand. Hind limb - from the thigh, lower leg, foot.
Most adult amphibians develop lungs as respiratory organs. However, they are not as perfect as in more highly organized groups of vertebrates. Therefore, skin respiration plays an important role in the life of amphibians.
The appearance of the lungs in the process of evolution was accompanied by the appearance of a second circle of blood circulation and a three-chambered heart. Although there is a second circle of blood circulation, due to the three-chambered heart, there is no complete separation of venous and arterial blood. Therefore, mixed blood enters most organs.
The eyes have not only eyelids, but also lacrimal glands for wetting and cleansing.
The middle ear appears with a tympanic membrane. (In fish, only the internal.) The eardrums are visible, located on the sides of the head behind the eyes.
The skin is naked, covered with mucus, it has many glands. It does not protect against water loss, so they live near water bodies. Mucus protects the skin from drying out and bacteria. The skin is made up of the epidermis and dermis. Water is also absorbed through the skin. The skin glands are multicellular, in fish they are unicellular.
Due to the incomplete separation of arterial and venous blood, as well as imperfect pulmonary respiration, the metabolism of amphibians is slow, like that of fish. They also belong to cold-blooded animals.
Amphibians breed in water. Individual development proceeds with transformation (metamorphosis). The frog larva is called tadpole.
Amphibians appeared about 350 million years ago (at the end of the Devonian period) from ancient lobe-finned fish. Their heyday occurred 200 million years ago, when the Earth was covered with huge swamps.
Musculoskeletal system of amphibians
In the skeleton of amphibians, there are fewer bones than in fish, since many bones grow together, while others remain cartilage. Thus, their skeleton is lighter than that of fish, which is important for living in an air environment that is less dense than water.
The brain skull fuses with the upper jaws. Only the lower jaw remains mobile. The skull retains a lot of cartilage that does not ossify.
The musculoskeletal system of amphibians is similar to that of fish, but has a number of key progressive differences. So, unlike fish, the skull and spine are movably articulated, which ensures the mobility of the head relative to the neck. For the first time, the cervical spine appears, consisting of one vertebra. However, the mobility of the head is not great, frogs can only tilt their heads. Although they have a neck vertebra, they do not appear to have a neck in appearance.
In amphibians, the spine consists of more sections than in fish. If fish have only two of them (trunk and tail), then amphibians have four sections of the spine: cervical (1 vertebra), trunk (7), sacral (1), caudal (one tail bone in anurans or a number of individual vertebrae in tailed amphibians) . In tailless amphibians, the caudal vertebrae fuse into one bone.
The limbs of amphibians are complex. The anterior ones consist of the shoulder, forearm and hand. The hand consists of the wrist, metacarpus and phalanges of the fingers. The hind limbs consist of the thigh, lower leg and foot. The foot consists of the tarsus, metatarsus and phalanges of the fingers.
Limb belts serve as a support for the skeleton of the limbs. The belt of the forelimb of an amphibian consists of the scapula, clavicle, crow bone (coracoid), common to the belts of both forelimbs of the sternum. The clavicles and coracoids are fused to the sternum. Due to the absence or underdevelopment of the ribs, the belts lie in the thickness of the muscles and are not indirectly attached to the spine in any way.
The belts of the hind limbs consist of the ischial and ilium bones, as well as the pubic cartilages. Growing together, they articulate with the lateral processes of the sacral vertebra.
The ribs, if present, are short and do not form a chest. Tailed amphibians have short ribs, tailless amphibians do not.
In tailless amphibians, the ulna and radius are fused, and the bones of the lower leg are also fused.
The muscles of amphibians have a more complex structure than those of fish. The muscles of the limbs and head are specialized. Muscle layers break up into separate muscles, which provide movement of some parts of the body relative to others. Amphibians not only swim, but also jump, walk, crawl.
Digestive system of amphibians
The general plan of the structure of the digestive system of amphibians is similar to that of fish. However, there are some innovations.
The anterior horse of the tongue of frogs adheres to the lower jaw, while the posterior one remains free. This structure of the tongue allows them to catch prey.
Amphibians have salivary glands. Their secret wets food, but does not digest it, as it does not contain digestive enzymes. The jaws have conical teeth. They serve to hold food.
Behind the oropharynx is a short esophagus that opens into the stomach. Here the food is partially digested. The first section of the small intestine is the duodenum. A single duct opens into it, where the secrets of the liver, gallbladder and pancreas enter. In the small intestine, food digestion is completed and nutrients are absorbed into the blood.
Undigested food remnants enter the large intestine, from where they move to the cloaca, which is an expansion of the intestine. The ducts of the excretory and reproductive systems also open into the cloaca. From it, undigested residues enter the external environment. Fish do not have a cloaca.
Adult amphibians feed on animal food, most often various insects. Tadpoles feed on plankton and plant matter.
1 Right atrium, 2 Liver, 3 Aorta, 4 Oocytes, 5 Large intestine, 6 Left atrium, 7 Heart ventricle, 8 Stomach, 9 Left lung, 10 Gallbladder, 11 Small intestine, 12 Cloaca
Respiratory system of amphibians
Amphibian larvae (tadpoles) have gills and one circle of blood circulation (like in fish).
In adult amphibians, lungs appear, which are elongated sacs with thin elastic walls that have a cellular structure. The walls contain a network of capillaries. The respiratory surface of the lungs is small, so the bare skin of amphibians also participates in the breathing process. Through it comes up to 50% oxygen.
The mechanism of inhalation and exhalation is provided by raising and lowering the floor of the oral cavity. When lowering, inhalation occurs through the nostrils, when raised, air is pushed into the lungs, while the nostrils are closed. Exhalation is also carried out when the bottom of the mouth is raised, but at the same time the nostrils are open, and the air exits through them. Also, when exhaling, the abdominal muscles contract.
In the lungs, gas exchange occurs due to the difference in the concentrations of gases in the blood and air.
The lungs of amphibians are not well developed to fully provide gas exchange. Therefore, skin respiration is important. Drying out amphibians can cause them to suffocate. Oxygen first dissolves in the fluid covering the skin, and then diffuses into the blood. Carbon dioxide also first appears in the liquid.
In amphibians, unlike fish, the nasal cavity has become through and is used for breathing.
Under water, frogs breathe only through their skin.
The circulatory system of amphibians
The second circle of blood circulation appears. It passes through the lungs and is called the pulmonary, as well as the pulmonary circulation. The first circle of blood circulation, passing through all organs of the body, is called large.
The heart of amphibians is three-chambered, consists of two atria and one ventricle.
The right atrium receives venous blood from the organs of the body, as well as arterial blood from the skin. The left atrium receives blood from the lungs. The vessel that empties into the left atrium is called pulmonary vein.
Atrial contraction pushes blood into the common ventricle of the heart. This is where the blood mixes.
From the ventricle, through separate vessels, blood is directed to the lungs, to the tissues of the body, to the head. The most venous blood from the ventricle enters the lungs through the pulmonary arteries. Almost pure arterial goes to the head. The most mixed blood entering the body is poured from the ventricle into the aorta.
This separation of the blood is achieved by a special arrangement of vessels emerging from the distribution chamber of the heart, where blood enters from the ventricle. When the first portion of blood is pushed out, it fills the nearest vessels. And this is the most venous blood, which enters the pulmonary arteries, goes to the lungs and skin, where it is enriched with oxygen. From the lungs, blood returns to the left atrium. The next portion of blood - mixed - enters the aortic arches going to the organs of the body. The most arterial blood enters the distant pair of vessels (carotid arteries) and goes to the head.
excretory system of amphibians
The kidneys of amphibians are trunk, have an oblong shape. Urine enters the ureters, then flows down the wall of the cloaca into the bladder. When the bladder contracts, urine flows into the cloaca and out.
The excretion product is urea. It takes less water to remove it than to remove ammonia (which is produced by fish).
In the renal tubules of the kidneys, water is reabsorbed, which is important for its conservation in air conditions.
Nervous system and sense organs of amphibians
There were no key changes in the nervous system of amphibians in comparison with fish. However, the forebrain of amphibians is more developed and is divided into two hemispheres. But their cerebellum is worse developed, since amphibians do not need to maintain balance in the water.
Air is more transparent than water, so vision plays a leading role in amphibians. They see further than fish, their lens is flatter. There are eyelids and nictitating membranes (or an upper fixed eyelid and a lower transparent movable one).
Sound waves travel worse in air than in water. Therefore, there is a need for a middle ear, which is a tube with a tympanic membrane (visible as a pair of thin round films behind the eyes of a frog). From the tympanic membrane, sound vibrations are transmitted through the auditory ossicle to the inner ear. The Eustachian tube connects the middle ear to the mouth. This allows you to weaken the pressure drops on the eardrum.
Reproduction and development of amphibians
Frogs start breeding at about 3 years of age. Fertilization is external.
Males secrete seminal fluid. In many frogs, the males attach themselves to the backs of the females, and while the female spawns for several days, she is poured with seminal fluid.
Amphibians spawn less eggs than fish. Clusters of caviar are attached to aquatic plants or float.
The mucous membrane of the egg swells greatly in water, refracts sunlight and heats up, which contributes to the faster development of the embryo.
Development of frog embryos in eggs
An embryo develops in each egg (usually about 10 days in frogs). The larva that emerges from the egg is called a tadpole. It has many features similar to fish (two-chambered heart and one circle of blood circulation, breathing with the help of gills, lateral line organ). At first, the tadpole has external gills, which then become internal. The hind limbs appear, then the front. The lungs and the second circle of blood circulation appear. At the end of metamorphosis, the tail resolves.
The tadpole stage usually lasts several months. Tadpoles eat plant foods.
