What substances are formed during respiration. Respiration of plants. Plant growth and respiration

Respiration is an important process of gas exchange between the human body and the environment. Blood is a carrier of gases. It contains a special pigment - hemoglobin, which transports oxygen and carbon dioxide.

In the cell, oxygen participates in metabolic processes, during which energy is released and water and decay products are formed. This is a set of gas exchange processes occurring in the body. The human body “takes” oxygen from the air, which enters organs and cells, and in return “gives” the resulting carbon dioxide.

At rest, a person inhales and exhales 0.5 liters of air each time. On average, 16 breaths are taken per minute. When performing physical work, more air is used.

Respiratory processes

Breathing is a physical and chemical process consisting of complex stages. Simplifying all these stages a little, breathing can be divided into external, internal and cellular.

External respiration is the inhalation and exhalation of air. Air enters the lungs through the respiratory tract (nose, pharynx, trachea, bronchi). Passing through the respiratory tract, it is cleansed, warmed and moisturized.

The respiratory process is regulated by the respiratory center, which is located in the medulla oblongata: when you inhale, air enters the lungs, while the ribs and diaphragm rise. Exhalation follows immediately. When you exhale, the ribs and diaphragm lower.

When exhaling, the abdominal muscles are the first to be activated. After exhalation, breathing stops for a very short time. At this moment, gas exchange occurs in the alveoli and blood vessels of the lungs. Red blood cells that enter the capillaries give off carbon dioxide and then take up oxygen, which they again distribute throughout the body.

Gas exchange (like all other respiratory processes in the human body) occurring in the lungs is determined by different concentrations of gases. First, the small blood vessels of the lungs contain high levels of carbon dioxide, so it enters the alveoli of the lungs, where its concentration is negligible. The oxygen content in the alveoli of the lungs is much higher than in the blood, so from there it enters the blood.

Internal (tissue) respiration is closely related to external respiration. Blood saturated with oxygen enters the tissues through the arteries, from where oxygen enters the tissue fluid. At the same time, carbon dioxide (dissolved carbon dioxide) enters the blood, which moves through the veins back to the lungs.

From tissue fluid, oxygen enters the cells of the body. Oxygen is needed to “burn” nutrients that enter the cells along with the blood. In this biological process of “combustion” (oxidation), so-called enzymes (enzymes) take part - proteins following one another, “transferring” oxygen to each other until the nutrients are completely “burnt”.

Finally, the oxygen combines with the hydrogen atoms created by the “combustion” process to form water. In addition, during oxidation, energy (heat) is released and the final breakdown product is carbon dioxide, which leaves the cells in the form of carbon dioxide and again enters the lungs with the blood, from where it is exhaled.

The respiratory center is located in the medulla oblongata. It acts in conjunction with the intermediate structures of the brain, ensuring the implementation of respiratory movements and the breathing process itself. When performing heavy physical work, the concentration of carbon dioxide increases, therefore, to restore balance, the need for oxygen increases and breathing quickens. Despite the fact that breathing is an involuntary process, it can be subordinated to your will. However, if breathing becomes too rapid, carbon dioxide is removed from the blood too quickly, which can cause breathing to stop.

Ventilation may be impaired due to narrowing of the airways; reducing the amount of mucus on the respiratory surface of the lungs; pulmonary circulatory disorders. Breathing may also be impaired due to changes in the composition of the inhaled air or the presence of harmful substances in the air.

According to biology, the respiration of plants and animals is a unique and universal process. It acts as an integral property of any organism inhabiting the Earth. Let us next consider how plant respiration occurs.

Biology

The life of organisms, like any manifestation of their activity, is directly related to energy consumption. Plant respiration, nutrition, organs, photosynthesis, movement and absorption of water and necessary compounds, as well as many functions are associated with the continuous satisfaction of necessary needs. Organisms require energy. It comes from the nutritional compounds consumed. In addition, the body needs plastic substances that serve as building materials for cells. The breakdown of these compounds, which occurs during breathing, is accompanied by the release of energy. It ensures the satisfaction of vital needs.

Plant growth and respiration

These two processes are closely related to each other. Full respiration of plants ensures the active development of the body. The process itself is presented as a complex system, including many coupled redox reactions. During them, the chemical nature of organic compounds is changed and the energy present in them is used.

general characteristics

Cellular respiration of plants is an oxidative process that occurs with the participation of oxygen. During it, the breakdown of compounds occurs, which is accompanied by the formation of chemically active products and the release of energy. The overall equation for the entire process looks like this:

С6Н12О6 + 602 > 6С02 + 6Н20 + 2875 kJ/mol

Not all the energy that is released can be used to support vital processes. The body needs mainly that part of it that is concentrated in ATP. In many cases, the synthesis of adenosine triphosphate is preceded by the formation of a difference in electric charges on the membrane. This process is associated with differences in the concentration of hydrogen ions on different sides. According to modern data, not only adenosine triphosphate, but also the proton gradient acts as a source of energy to ensure the life of the cell. Both forms can be used to activate the processes of synthesis, supply, movement of nutrient compounds and water, and the formation of a potential difference between the external environment and the cytoplasm. Energy that is not stored in ATP and the proton gradient is largely dissipated as light or heat. It is useless for the body.

Why is this process needed?

What is the importance of respiration in plants? This process is considered central to the life of the body. The energy released during respiration is used to grow and maintain the already developed parts of the plant in an active state. However, these are not all the points that determine the importance of this process. Let's consider the main role of plant respiration. This process, as mentioned above, is a complex redox reaction. It takes place in several stages. At intermediate stages, the formation of organic compounds occurs. They are subsequently used in various metabolic reactions. Among the intermediate compounds, pentoses and organic acids can be distinguished. Plant respiration is thus a source of many metabolites. From the overall equation it can be seen that water is also formed during this process. In conditions of dehydration, it can save the body from death. In summary, respiration is the opposite of photosynthesis. However, in some cases these processes complement each other. They contribute to the supply of both energy equivalents and metabolites. In some cases, when energy is released in the form of heat, plant respiration leads to a wasteful loss of dry matter. Therefore, increasing the intensity of this process is not always beneficial for the body.

Peculiarities

Plants respire around the clock. During this process, organisms absorb oxygen from the atmosphere. In addition, they inhale O2, formed in them as a result of photosynthesis and available in the intercellular spaces. During the day, oxygen mainly enters through the stomata of young shoots and leaves, lenticels of stems, and the skin of roots. At night, almost all plants have them covered. During this period, plants use oxygen for respiration, which has accumulated in the intercellular spaces and was formed during photosynthesis. Oxygen entering the cells oxidizes the organic complex compounds present in them, converting them into water and carbon dioxide. In this case, the energy spent on their formation during photosynthesis is released. Carbon dioxide is removed from the body through the cell surface of young roots, lentils, and stomata.

Experiments

To make sure that plant respiration actually occurs, you can do the following:

How to use the acquired knowledge?

In the process of growing crops, the soil becomes compacted, and the air content in it is significantly reduced. To improve the flow of life processes, soil is loosened. Those plants that are grown in swampy (heavily moist) soils especially suffer from a lack of oxygen. Improving the O2 supply is achieved by draining the land. The breathing process is negatively affected by dust that settles on the leaves. Its small solid particles clog the stomata, which significantly impedes the flow of oxygen into the leaves. In addition, impurities that enter the air when various types of fuel are burned in industrial enterprises also have a harmful effect. In this regard, when landscaping urban areas, dust-resistant trees are usually planted. These, for example, include horse chestnut, linden, bird cherry, and poplar. During grain storage, special attention should be paid to their moisture content. The fact is that as its level increases, the intensity of breathing increases. This, in turn, contributes to the fact that the seeds begin to become very warm with the generated heat. This, in turn, negatively affects the embryos - they die. To avoid such consequences, seeds that are stored must be dry. The room itself must be well ventilated.

Conclusion

Thus, plant respiration is of great importance to ensure their normal development at any stage. Without this process, it is impossible not only to ensure the normal functioning of the body, but also to form all its parts. During respiration, the most important compounds are formed, without which the plant’s existence is impossible. This complex, multi-stage process is a central link in the entire life of any organism. Knowledge about this helps to ensure proper conditions for growing and storing cultivated plants, achieving high yields of grain and other agricultural crops. It is known that breathing produces heat. Near some crops, air temperatures can rise by more than 10 degrees. This property is used by humans for various purposes.

Removal of harmful substances from the body occurs through breathing, sweat, urine, feces, through vomiting, laxatives and a number of medical procedures. Excessive retention of harmful substances in the body and their accumulation cause loss of appetite and cause blockages.

So, with thirst, dry mouth, dizziness, heart pain, and memory loss appear. If the separation of saliva and sputum is impaired, illnesses occur, strength disappears, and appetite disappears. When sneezing is delayed, sensitivity becomes dulled, headaches appear, cramps in the muscles of the limbs and the back of the head, while the mouth curls and the jaw sag. When suppressing yawning, the same consequences occur as when delaying sneezing. Hunger causes dizziness and weakness. Excess lactic acid leads to fatigue in the body. The accumulation of gases causes constipation, tumors, intestinal colic, impairs vision, causes chilliness, and various heart diseases. When feces are retained, headaches and convulsive contractions of the arms and legs may occur. When urine is retained, stones form. When sperm is retained, urination becomes difficult, prostatitis and impotence develop. Lack of sleep leads to frequent yawning, weakness, heaviness in the head, indigestion, and darkness in the eyes.

If these disorders occur, you must fast, inhale aloe smoke through your mouth and rinse your mouth with aloe decoction. You can also cleanse the body with vomiting and laxatives, but these drugs are contraindicated “for people with weakened soft tissues of the lower abdomen. Hippocrates recommended inducing vomiting no more than twice in a row within a month. Vomiting spews out mucus and bile, eliminates

indigestion, cleanses the stomach (after all, the stomach does not have such a cleansing factor as bile does for the intestines), and also relieves heaviness in the head, clears vision, strengthens the body, and helps with ulcers that form in the kidneys and bladder. It is a powerful remedy for leprosy, poor complexion and gastric epilepsy, jaundice, parkinsonism and paralysis. It is also an excellent treatment for patients with lichen. Vomiting is resorted to once a month when the stomach is full, without observing a certain frequency. After vomiting, you should rinse your mouth and face with vinegar diluted with water to get rid of heaviness in the head.

Laxatives should not be taken if there is dry excess in the intestines (as happens with constipation); solid masses must first be removed using enemas or thinning agents.

For example, using a sauna for several days before taking a laxative has a thinning effect on the excess, but it is necessary that a short time elapses between visiting the sauna and taking the medicine. The laxative decoction should be drunk warm, then warm the stomach and feet, and move a little. In this case, you should periodically drink small sips of hot water in such an amount that would not interfere with the action of the medicine. Anyone who has taken a laxative should not eat or drink until the medicine wears off. You can't sleep at this time. Bad breath from the medicine taken is eliminated with barley oatmeal powder. It is more useful to take a laxative in spring or autumn.

More details about cleansing procedures are described in the “Therapeutic Procedures” section.

Tibetan medicine identifies a number of general principles of maintaining health:

Keep your body clean and bathe often. Bathing enhances passion, strength, prolongs life, washes away sweat, dirt, smell, relieves fatigue, removes thirst and heat;

Keep your tongue and soul pure, drive away sins from them. Refuse bad deeds, no matter how much they encourage you, do good deeds, no matter how much they hinder you. Don’t take everything you hear as truth, but check it thoroughly. Say everything you hear to yourself and draw a brief conclusion. Don’t listen to women, give them your words seriously;

Don’t hide from those who love and are faithful, talk openly. Be slow but firm, communicate peacefully and quickly. Don’t let your enemies go down, but pacify them in a noble way. Keep friendship, affection, do not forget about good deeds. Respect your teacher, father, uncle, and all old people in general. Live with your mind and heart in harmony with your fellow countrymen, relatives, and friends;

Admit your wrongs and defeat, and if you win, be restrained. If you are wise, do not be arrogant, and if you are rich, know when to stop. Do not trample low people, do not envy high people. Avoid friendship and enmity with scoundrels. Don’t bother with someone else’s;

Beware of mistakes and sins. So as not to repent later, do not give power to bad people. Don’t waste your mental strength, but be broad-minded. Help the suffering, sick and poor in any way you can. Treat everyone, starting with worms, as you treat yourself. Smile honestly and sincerely, speak directly.

Respiration is a universal physiological process inherent in all living organisms: bacteria, animals, plants.

In plants, respiration performs two important biological functions. First, it provides the plant with energy in the form of ATP. Secondly, respiration is a multi-step process during which numerous intermediate substances are formed, which in themselves are valuable for plant metabolism. They are directed to certain biochemical reactions. This function of respiration can be defined as the creation of the plant's metabolic fund.

The overall equation for the breathing process is as follows:

This equation, which shows only the initial and final products of the process, indicates that respiration is the oxidation of organic matter, during which complex organic matter is broken down into carbon dioxide and water to produce chemical energy.

During respiration, the breakdown of organic substances occurs, and therefore the biochemical essence of respiration is the opposite of photosynthesis. So, the products of the photosynthetic process are consumed through two channels: the main part of the organic substances formed during photosynthesis is directed to the construction of the plant body itself, and the other (smaller, more often) is included in the respiratory process to release the energy bound in these substances.

The energy that is released during the process of respiration is partly released in the form of heat, and part is stored in the form of chemical energy, which is bound and stored in the form of ATP. This process is called oxidative phosphorylation . It corresponds to the equation:

The synthesis of ATP and their charging with energy is the main function of the respiratory process. Scheme in Fig. Figure 3.13 shows the variety of tasks solved during plant respiration due to the production of ATP.

During respiration, organic substances are consumed, and the weight of the plant decreases. So, for example, if a grain of corn lives 0.529 g when sown, then after two days of germination its weight is only 0.290 g. During this time, it spends almost 45% of its reserve nutrients on respiration.

Breathing also causes changes in the composition of the air around the plant. The amount of oxygen decreases (it is consumed during breathing), and the amount

Rice. 3.13.

carbon dioxide increases (it is released during breathing). Respiration is also associated with the production of thermal energy. Usually it is released a little, but during the respiration of germinating seeds, the amount of heat released can be so large that the seeds heat up to a temperature of 60-90 ° C.

Localization of breathing

Unlike animals and humans, plants do not have special organs or structures that perform the function of respiration. It is carried out by all living cells, in the protoplast of which there are special organelles responsible for the respiratory function - mitochondria, their number in a single cell ranges from 50 to 5000 pieces.

Breath chemistry

Respiration is a complex redox process that occurs in several stages. During it, the initial respiratory material is sequentially oxidized through a system of interconnected reactions with the release of energy. Energy, as noted above, goes to the synthesis of ADP.

Depending on the properties of the respiratory material, the genetic characteristics of plants and other factors, respiration can be carried out in various ways. During the oxidation of carbohydrates, which occurs more often in plants, respiration occurs in two successive stages.

At the first stage, the initial respiratory material is oxidized under oxygen-free, that is, anaerobic, conditions to pyruvic acid. This process is called glycolysis. At the second stage, pyruvic acid is oxidized to carbon dioxide with the participation of oxygen, that is, under aerobic conditions. This process was discovered and studied by the English scientist of German origin G. Krebs. For this achievement, the scientist received the Nobel Prize in 1953, and the complex of transformations itself was called Krebs cycle .

Glycolysis . Glycolysis is represented by a series of sequential reactions. It is not localized in mitochondria, but usually in the cytosol of cells. The general scheme of the transformation of substances during glycolysis is shown in Fig. 3.14.

During glycolysis, glucose first undergoes the process of phosphorylation with the formation of glucose phosphate by consuming one molecule of ATP, increases its reactivity, and then is converted into fructose phosphate using the enzyme isomerase. Fructose phosphate undergoes phosphorylation once again to form fructose diphosphate. This process takes another ATP molecule.

The next stage of glycolysis consists of the cleavage of fructose diphosphate by the enzyme aldolase into two trioses - phosphoglyceraldehyde and phosphodioxyacetone. These two substances can be mutually converted to each other under the action of the appropriate isomerase, so that their ratio is always maintained at 1: 1, and as phosphoglyceraldehyde is consumed, its fund is replenished by phosphodioxyacetone.

Subsequently, only phosphoglyceraldehyde is involved in the oxygenation process. Under the action of an enzyme complex containing a special enzyme phosphoglycerol-aldehyde dehydrogenase, it is oxidized without the participation of atmospheric oxygen with simultaneous additional phosphorylation to diphosphoglyceric acid.

Rice. 3.14.

Diphosphoglyceric acid, in the process of further transformations, is dephosphorylated with the synthesis of ATP molecules and turns into pyruvic acid. As a result of glycolysis, two molecules of pyruvic acid are formed from one monosaccharide molecule. No carbon dioxide is released in this first stage of the respiratory process. The net energy output of glycolysis is two molecules of ATP.

Krebs cycle. In the Krebs cycle, pyruvic acid undergoes a series of cyclic transformations, during which several tri- and dicarboxylic acids are formed. The general scheme of chemical transformations of substances in the Krebs cycle is shown in Fig. 3.15.

Rice. 3.15.

A key role in the aerobic phase of respiration is played by decarboxylation reactions, leading to shortening of the chain of carbon atoms in pyruvic acid and the release of carbon dioxide. Further reactions of the Krebs cycle are associated with the restoration of the supply of oxaloacetic acid, necessary for inclusion in the cyclic reactions of acetic acid. In total, the oxidation of one pyruvic acid molecule releases three CO2 molecules.

The main links in electron transport chains are oxidase reductase enzymes. All enzymes - participants in the electron transport chain are bougie with the exception of ubiquinone, which is a lipid in the chemical nature.

A total of 36 ATP molecules are produced in the Krebs cycle. Together with glycolysis, this produces 38 ATP molecules. Taking the energy value of one ATP molecule to be 7 kcal, we see that breathing releases 266 kcal of chemical energy from respiratory material.

Assessing the biochemical features of plant respiration, it should be noted that it provides plants with chemical energy and connects various parts of plant metabolism. An important feature of plant respiration is its polyfunctionality, which consists in the ability to attract various substances from carbohydrates to proteins for oxidative dissimilation.

The biochemical function of respiration, as noted above, is not limited to the production of energy for the plant. This process represents one of the central links in metabolism, consuming a wide range of metabolites and at the same time supplying a number of essential products for the metabolism of carbohydrates, lipids and proteins, which are used to build complex organic compounds. First of all, due to the Krebs cycle, carbohydrate, lipid and protein metabolism are connected with each other.

1. Which gas is absorbed and which is released during respiration?
2. What gas supports combustion?
3. What process is called photosynthesis?

All living organisms require energy to function. Plants and animals receive it through the process of respiration.

You have watched many times how wood burns in a fire or stove. When burning, a large amount of energy is released in the form of heat and light. Where does it come from? When burning, organic substances interact with oxygen. Complex organic substances break down into simpler ones. And the light energy that was used by plants during photosynthesis to form organic substances is released in the form of heat and light.

Burning is similar to breathing. But combustion proceeds very violently, releasing a large amount of energy. During respiration, the decomposition of organic substances occurs gradually, in several stages. At each stage, a small amount of energy is released, which the body uses for various vital processes. Thus, breath- a process during which living organisms absorb oxygen from the environment and release carbon dioxide. This process occurs with the release of energy. Different organisms perform breathing differently.

Animal breathing. Single-celled organisms, primitive multicellular organisms (sponges, coelenterates), and a number of worms breathe, absorbing oxygen from the air or water over the entire surface of the body. Respiration through the skin accounts for about 50% of gas exchange in most amphibians.

As the structure of the body becomes more complex, different groups of animals develop special respiratory organs (Fig. 52): gills(in most aquatic invertebrates, fish, amphibian larvae); trachea(in insects); lungs(in terrestrial mollusks, amphibians, reptiles, birds and mammals).

Rice. 52. Animal respiratory organs: a - fish gills; b - insect trachea; c - lungs of amphibians

Plant respiration. In plants, respiration also provides the oxygen needs of all tissues and cells. The growing organs of the plant respire most intensively, while dry seeds respire very weakly. The plant does not have special respiratory organs. In higher plants, the leading role in gas exchange is played by stomata in the skin of leaves and green stems and lentils cork layer of bark (Fig. 53). In large plants, between loosely arranged cells there are air spaces (intercellular spaces), from which oxygen enters the cells.

Rice. 53. Stomata (a), lentil (b)

The main part of the energy generated during respiration is used by the plant for vital processes, and a small part is released in the form of heat. The above-ground part of the plant is surrounded by air. It is more difficult for the roots, since there is half as much oxygen in the soil. Therefore, in plant growing, various techniques are used to improve root respiration. Special cultivators loosen the soil and increase the flow of air to the roots.

Answer the questions

1. What process is called breathing?
2. What is the significance of breathing?
3. What animal respiratory organs do you know?
4. How can you prove that plants breathe?

New concepts

Breath. Gills. Trachea. Lungs. Stomata. Lentils.

Think!

Why is it difficult to detect the process of respiration in plants in the light?

My laboratory

In winter, under the ice in fresh water bodies there is often not enough oxygen and therefore fish kills occur. To avoid this, people make holes in the ice or pump in air using pumps.

Simple experiments will help you make sure that plants breathe.

Experience 1. Water was poured into two identical vessels, in which a small amount of minerals needed by the plant was dissolved. In each vessel, bean, bean or pea sprouts were immersed in the solution with their roots and secured. The solution in one of the vessels was saturated with air daily using a spray bottle. The other vessel was tightly closed with a lid so that air did not penetrate into it. The plants in the second vessel died after some time. Draw a conclusion about the cause of plant death.

Experience 2. Pour water into the bottom of the jar and fill up to 1/3 of its height with germinating pea, bean or wheat seeds. Close the jar tightly with the lid. Pour the same amount of dry seeds into another jar. Keep both jars at a temperature of 20-25 °C.

After a day, lower a burning splinter into both jars. Explain why in a jar with dry seeds a splinter will burn for some time, but in a jar with germinating seeds the splinter will immediately go out. Draw a conclusion from the experience.

Make the experience more challenging: Place one jar of germinating seeds in the refrigerator and the other in a warm place. After one or two days, add smoldering splinters to the jars with germinating seeds. In which jar will the torch go out and why? Plants respire more intensely in a warm place. But the main condition for breathing is the presence of oxygen in the air.

How does a person use knowledge about plant respiration in his activities? To store seeds in granaries (elevators), it is necessary to store dry seeds. The room should be ventilated so that fresh air is constantly supplied to the seeds. Therefore, in granaries, in addition to natural ventilation through windows and doors, ventilation is carried out using electrical appliances, which allows grain to be preserved for a number of years.

The breathing of leaves is prevented by a layer of dust that settles on them from the air. Small solid particles close the stomata and prevent air from entering the leaf. Therefore, indoor plants should be periodically cleaned of dust.

Harmful impurities in the air, the result of emissions from industrial enterprises, also have a negative effect on plants. That is why, when landscaping cities and towns, plants that are resistant to harmful substances and air dust are planted (Fig. 54). Poplar, linden, yellow acacia, oak and some other plants have such properties.

Rice. 54. Landscaping