Why does the breathing intensity increase as the load increases? Explain, using knowledge of the biochemistry of energy metabolism, why a person becomes hot when performing physical activity? What is the role of the circulatory system

Continuation. See No. 7, 9/2003

Laboratory work for the course “Man and his health”

Laboratory work No. 7. Pulse counting before and after dosed exercise

By contracting, the heart works like a pump and pushes blood through the vessels, providing oxygen and nutrients and freeing cells from waste products. Excitation periodically occurs in special cells in the heart muscle, and the heart spontaneously contracts rhythmically. The central nervous system constantly controls the functioning of the heart through nerve impulses. There are two types nervous influences on the heart: some reduce the heart rate, others speed it up.

The heart rate depends on many reasons - age, condition, load, etc.

With each contraction of the left ventricle, the pressure in the aorta increases, and the vibration of its wall spreads in the form of a wave through the vessels. The vibration of the walls of blood vessels in rhythm with the contractions of the heart is called the pulse. Goals:

learn to count your pulse and determine your heart rate; draw a conclusion about the features of its work in different conditions. Equipment:

clock with second hand.

PROGRESS 1. Find the pulse by placing two fingers, as shown in Fig. 6 on inner side

wrists. Apply light pressure. You will feel your pulse beating. 2. Count the number of beats in 1 minute in calm state

. Enter the data into the table. 5.

4. After 5 minutes of rest in a sitting position, count your pulse and enter the data into the table. 5.

Questions
1. In what other places besides the wrist can you feel the pulse? Why can the pulse be felt in these places of the human body?
2. What ensures continuous blood flow through the vessels?
3. What significance do changes in the strength and frequency of heart contractions have for the body?

4. Compare the results in the table. 5. What conclusion can be drawn about the work of your own heart at rest and under load?

Problematic issues
1. How to prove that the pulse, which is felt in some points of the body, is waves propagating along the walls of the arteries, and not a portion of the blood itself? 2. Why do you think the most different nations

Laboratory work No. 8. First aid for bleeding

The total volume of circulating blood in the body of an adult is on average 5 liters. Loss of more than 1/3 of blood volume (especially rapid) is life-threatening. The causes of bleeding are damage to blood vessels as a result of injury, destruction of the walls of blood vessels in some diseases, increased permeability of the vessel wall and impaired blood clotting in a number of diseases.
The leakage of blood is accompanied by a decrease blood pressure, insufficient oxygen supply to the brain, heart muscles, liver, kidneys. If assistance is not provided in a timely or competent manner, death may occur.

With each contraction of the left ventricle, the pressure in the aorta increases, and the vibration of its wall spreads in the form of a wave through the vessels. The vibration of the walls of blood vessels in rhythm with the contractions of the heart is called the pulse. learn to apply a tourniquet; be able to apply knowledge of structure and function circulatory system

learn to count your pulse and determine your heart rate; draw a conclusion about the features of its work in different conditions., explain the actions when applying a tourniquet for arterial and severe venous bleeding.

rubber tube for a tourniquet, a stick for twisting, a bandage, paper, a pencil. Safety precautions:

clock with second hand.

Be careful when twisting the tourniquet so as not to damage the skin.

1. Apply a tourniquet to a friend’s forearm to stop conditional arterial bleeding. 2. Bandage the site of the conditioned artery injury. Write down the time on a piece of paper applying a tourniquet

and place it under the tourniquet. 3. Apply pressure bandage

4. After 5 minutes of rest in a sitting position, count your pulse and enter the data into the table. 5.

on the forearm of a comrade to stop conditional venous bleeding.
1. How did you determine the type of bleeding?
2. Where should the tourniquet be applied? Why?
3. Why do you need to put a note under the tourniquet indicating the time it was applied? 4. What is the danger of arterial and strong?
venous bleeding
5. What is the danger of incorrectly applying a tourniquet, why should it not be applied for more than 2 hours?

4. Compare the results in the table. 5. What conclusion can be drawn about the work of your own heart at rest and under load?

6. In Fig. 7 Find places where you need to press large arteries during heavy bleeding. 1. Blockage of a blood vessel by a thrombus can cause gangrene and tissue death. It is known that gangrene can be “dry” (when the tissues wrinkle) or “wet” (due to developing edema
). Which type of gangrene will develop if the following is thrombosed: a) an artery; b) vein? Which of these options happens more often and why?

2. In the limbs of mammals, arterial vessels are always located deeper than veins of the same branching order. What is the physiological meaning of this phenomenon?

An adult, depending on age and height, in a calm state, with each breath inhales 300–900 ml of air and exhales approximately the same amount. In this case, the capabilities of the lungs are not fully used. After any calm inhalation, you can inhale another additional portion of air, and after a calm exhalation, exhale some more of it. The maximum amount of air exhaled after take a deep breath called vital capacity lungs. On average it is 3–5 liters. As a result of training, the vital capacity of the lungs may increase. Large portions of air entering the lungs during inhalation help supply the body with sufficient quantity

oxygen without increasing the breathing rate. Target:

learn to count your pulse and determine your heart rate; draw a conclusion about the features of its work in different conditions. learn to measure the vital capacity of the lungs.

rubber tube for a tourniquet, a stick for twisting, a bandage, paper, a pencil. balloon, ruler.

clock with second hand.

do not participate in the experiment if you have problems with the respiratory system.

I. Tidal volume measurement

1. After a calm inhalation, exhale into the balloon. Note:

do not exhale forcefully.

2. Immediately tighten the hole in the balloon to prevent air from escaping. Place the ball on a flat surface, such as a table, and have your partner hold a ruler to it and measure the diameter of the ball, as shown in Fig. 8. Enter the data into the table. 7.

II. Vital capacity measurement. 1. After calm breathing

, inhale as deeply as you can, and then exhale as deeply as possible into the balloon. 2. Tighten the hole immediately hot air balloon

. Measure the diameter of the ball and enter the data in the table. 6.

3. Deflate the balloon and repeat the same two more times. Print the average and enter the data into the table. 6.

4. Using graph 1, convert the obtained values ​​for the diameter of the balloon (Table 6) into lung volume (cm 3). Enter the data into the table. 7.

III. Calculation of vital capacity

1. Research shows that lung volume is proportional to the surface area of ​​the human body. In order to find the surface area of ​​your body, you need to know your weight in kilograms and height in centimeters. Enter this data into the table. 8.

3. To calculate the vital capacity of your lungs, multiply the surface area of ​​your body by the vital capacity coefficient, which is 2000 ml/m2 for women and 2500 cm3/m2 for men. Enter the data on the vital capacity of your lungs in the table. 8.

1. Why is it important to take the same measurements three times and average them?
2. Do your performance differ from that of your classmates? If so, why?
3. How to explain the differences in the results of measuring the vital capacity of the lungs and those obtained by calculation?
4. Why is it important to know the volume of exhaled air and the vital capacity of the lungs?

4. Compare the results in the table. 5. What conclusion can be drawn about the work of your own heart at rest and under load?

1. Even when you exhale deeply, some air remains in the lungs.
What does it matter?
2. Can vital capacity matter to some musicians? Explain your answer.

3. Do you think smoking affects lung capacity? How?

Laboratory work No. 10. The effect of physical activity on breathing rate The respiratory and cardiovascular systems ensure the exchange of gases. With their help, oxygen molecules are delivered to all tissues of the body, and removed from there carbon dioxide . Gases easily penetrate through cell membranes

oxygen without increasing the breathing rate.. As a result, the body cells receive the oxygen they need and are freed from carbon dioxide. This is the essence of the respiratory function. The body maintains an optimal ratio of oxygen and carbon dioxide by increasing or decreasing the breathing rate. The presence of carbon dioxide can be detected in the presence of the indicator bromothymol blue..

learn to count your pulse and determine your heart rate; draw a conclusion about the features of its work in different conditions. A change in the color of the solution is an indicator of the presence of carbon dioxide. establish the dependence of breathing frequency on physical activity

rubber tube for a tourniquet, a stick for twisting, a bandage, paper, a pencil. 200 ml bromothymol blue, 2 x 500 ml flasks, glass rods, 8 straws, 100 ml graduated cylinder, 65 ml 4% aqueous solution ammonia, pipette, clock with second hand.

clock with second hand.

Carry out the experiment with a solution of bromothymol blue in a laboratory coat. Be careful with glassware. Chemical reagents must be handled very carefully to avoid contact with clothing, skin, eyes, and mouth. If when executing

physical exercise

If you feel bad, sit down and talk to the teacher.

3 Repeat the same thing 2 more times, calculate the average number of breaths and enter the data into the table. 9.

Note: after each count you need to relax and rest.

II. Respiration rate after exercise

1. Run in place for 1 minute.

Note. If you feel unwell during the exercise, sit down and talk to your teacher.

2. Sit down and immediately count for 1 minute. number of breaths. Enter the data into the table. 9.

3. Repeat this exercise 2 more times, resting each time until breathing is restored.

Enter the data into the table. 9.

III. The amount of carbon dioxide (carbon dioxide) in exhaled air at rest

1. Pour 100 ml of bromothymol blue solution into the flask.

Note. 2. One of the students calmly exhales air through a straw into the flask with the solution for 1 minute.

Be careful not to get the solution on your lips.

After a minute, the solution should turn yellow. 3. Start adding drops into the flask, counting them, using a pipette ammonia solution

, stirring the contents of the flask from time to time with a glass rod.

4. Add ammonia drop by drop, counting the drops, until the solution turns blue again. Enter this number of drops of ammonia into the table. 10.

5. Repeat the experiment 2 more times using the same bromothymol blue solution. Calculate the average and enter the data into the table. 10.

IV. The amount of carbon dioxide in exhaled air after exercise

1. Pour 100 ml of bromothymol blue solution into the second flask.

2. Let the same student as in the previous experiment do the “running in place” exercise.

3. Immediately, using a clean straw, exhale into the flask for 1 minute.

4. Using a pipette, add ammonia drop by drop to the contents of the flask (counting the amount until the solution turns blue again).

5. In table. 10 add the number of drops of ammonia used to restore color.

6. Repeat the experiment 2 more times. Calculate the average and enter the data into the table. 10.

Conclusion
1. Compare the number of breaths at rest and after physical activity.
2. Why does the number of breaths increase after physical activity?
3. Does everyone in the class have the same results? Why?
4. What is ammonia in the 3rd and 4th parts of the work?

4. Compare the results in the table. 5. What conclusion can be drawn about the work of your own heart at rest and under load?

5. Is the average number of drops of ammonia the same when completing parts 3 and 4 of the task? If not, why not? 1. Why do some athletes inhale? pure oxygen
after strenuous exercise?
3. Nicotine from cigarettes, entering the bloodstream, constricts blood vessels. How does this affect the breathing rate?

To be continued

ANSWER: The generation of energy to ensure muscle work can be carried out by anaerobic oxygen-free and aerobic oxidative pathways. Depending on the biochemical characteristics of the processes occurring in this case, it is customary to distinguish three generalized energy systems that provide physical performance person:

alactic anaerobic, or phosphagenic, associated with the processes of ATP resynthesis mainly due to the energy of another high-energy phosphate compound - creatine phosphate KrP

glycolytic lactacid anaerobic, providing resynthesis of ATP and KrP due to the reactions of anaerobic breakdown of glycogen or glucose to lactic acid MK

aerobic oxidative, associated with the ability to perform work due to the oxidation of energy substrates, which can be carbohydrates, fats, proteins, while increasing the delivery and utilization of oxygen in working muscles.
Almost all the energy released in the body during the metabolism of nutrients is ultimately converted into heat. Firstly, the maximum coefficient useful action converting nutrient energy into muscle work, even at the most better conditions, is only 20-25%; the rest of the nutrient energy is converted into heat through intracellular chemical reactions.

Secondly, almost all the energy that actually goes into creating muscle work, however, becomes body heat, since this energy, except for a small part of it, is used to: 1 overcome the viscous resistance of movement of muscles and joints; 2 overcoming friction of blood flowing through blood vessels; 3 other similar effects resulting in energy muscle contractions turns into heat. Thermoregulation mechanisms, sweating, etc. are activated; the person is hot.

The drug ubinone (coenzyme Q) is used as an antioxidant that has an antihypoxic effect. The drug is used to treat diseases of cardio-vascular system, to improve performance during physical activity. Using knowledge of the biochemistry of energy metabolism, explain the mechanism of action of this drug.

ANSWER: Ubiquinones are fat-soluble coenzymes found predominantly in mitochondria eukaryotic cells. Ubiquinone is a component of the electron transport chain and is involved in oxidative phosphorylation. The maximum content of ubiquinone in organs with the highest energy needs, for example, in the heart and liver.

Tissue respiration complex 1 catalyzes the oxidation of NADH by ubiquinone.

With NADH and Succinate in complexes 1 and 2 respiratory chain transfer of e to ubinone occurs.

And then from ubinone to cytochrome c.

Two experiments were carried out: in the first study, mitochondria were treated with oligomycin, an ATP synthase inhibitor, and in the second, with 2,4-dinitrophenol, an uncoupler of oxidation and phosphorylation. How will ATP synthesis, the transmembrane potential, the rate of tissue respiration and the amount of CO2 released change? Explain why the endogenous uncouplers fatty acids and thyroxine have a pyrogenic effect?

ANSWER: ATP synthesis will decrease; the magnitude of the transmembrane potential will decrease; the rate of tissue respiration and the amount of CO2 released will decrease.

Some chemical substances can transport protons or other ions bypassing the proton channels of ATP synthase in the membrane; they are called protonophores and ionophores. In this case, the electrochemical potential disappears and ATP synthesis stops. This phenomenon is called uncoupling of respiration and phosphorylation. The amount of ATP decreases, ADP increases, and energy is released in the form warmth, Consequently, an increase in temperature is observed and pyrogenic properties are revealed.

56. Apoptosis is programmed cell death. For some pathological conditions(For example, viral infection) premature cell death may occur. The human body produces protective proteins that prevent premature apoptosis. One of them is the Bcl-2 protein, which increases the NADH / NAD+ ratio and inhibits the release of Ca 2+ from the ER. It is now known that the AIDS virus contains a protease that destroys Bcl-2. The rate of which energy metabolism reactions changes in this case and why? Why do you think these changes could be detrimental to cells?

ANSWER: Increases the NADH / NAD+ ratio hence increasing the rate of ORR reactions of the Krebs cycle.

At the same time, the oxidative decarboxylation reaction will accelerate, since Ca2+ is involved in the activation of inactive PDH. Since the NADH / NAD+ ratio will be reduced during AIDS, the rate of OBP reactions of the Krebs cycle will decrease.

Barbiturates (sodium amytal, etc.) are used in medical practice How sleeping pills. However, an overdose of these drugs exceeding 10 times the therapeutic dose can lead to fatal outcome. What is it based on? toxic effect barbiturates on the body?

Answer: Barbiturates, group medicinal substances, derivatives of barbituric acid, which have hypnotic, anticonvulsant and narcotic effects due to their inhibitory effect on the central nervous system. Barbiturates taken orally are absorbed into small intestine. When hitting bloodstream bind to proteins and are metabolized in the liver. Approximately 25% of barbiturates are excreted unchanged in the urine.

The main mechanism of action of barbiturates is due to the fact that they penetrate the internal lipid layers and liquefy the membranes nerve cells, disrupting their function and neurotransmission. Barbiturates block the excitatory neurotransmitter acetylcholine, while stimulating the synthesis and increasing the inhibitory effects of GABA. As addiction develops, cholinergic function increases while GABA synthesis and binding decreases. The metabolic component is to induce liver enzymes, reducing hepatic blood flow. Tissues become less sensitive to barbiturates. Barbiturates can cause an increase in the stability of nerve cell membranes over time. In general, barbiturates have an inhibitory effect on the central nervous system, which is clinically manifested as a hypnotic, sedative effect. in toxic doses they depress external breathing, activity of the cardiovascular system (due to inhibition of the corresponding center in medulla oblongata). sometimes disturbances of consciousness: stupor, stupor and coma. Causes of death: respiratory failure, spicy liver failure, shock reaction with cardiac arrest.

At the same time, due to breathing disorders, there is an increase in the level of carbon dioxide and a decrease in the level of oxygen in the tissues and blood plasma. Acidosis occurs - a violation acid-base balance in organism.

The action of barbiturates disrupts metabolism: it inhibits oxidative processes in the body, reduces the formation of heat. When poisoning occurs, the blood vessels dilate and heat is released to a greater extent. Therefore, patients' temperature decreases

58. For heart failure, injections of cocarboxylase containing thiamine diphosphate are prescribed. Given that heart failure is accompanied by a hypoenergetic state, and using knowledge of the effect of coenzymes on enzyme activity, explain the mechanism therapeutic action drug. Name the process that is accelerated in myocardial cells when this drug is administered

Answer: Cocarboxylase is a vitamin-like drug, a coenzyme that improves metabolism and energy supply to tissues. She improves metabolic processes nervous tissue, normalizes the functioning of the cardiovascular system, helps normalize the functioning of the heart muscle..

In the body, cocarboxylase is formed from vitamin B1 (thiamine) and plays the role of a coenzyme. Coenzymes are one of the parts of enzymes - substances that accelerate everything many times biochemical processes. Cocarboxylase is a coenzyme of enzymes involved in carbohydrate metabolism processes. In combination with protein and magnesium ions, it is part of the carboxylase enzyme, which has an active effect on carbohydrate metabolism, reduces the level of lactic and pyruvic acid in the body, and improves the absorption of glucose. All this helps to increase the amount of energy released, and therefore improve all metabolic processes in the body, and since our patient has a hypoenergetic state. That is, conditions in which ATP synthesis is reduced, the cause of which may be vitamin B1 hypovitaminosis, then when taking such medicine as cocarboxylase, the state of environmental activity will improve.

Cocarboxylase improves glucose absorption, metabolic processes in nervous tissue, and helps normalize the functioning of the heart muscle. Cocarboxylase deficiency causes an increase in blood acidity (acidosis), which leads to severe disorders of all organs and systems of the body, which can result in coma and death of the patient.

I HAVE NOT FOUND ANYTHING ABOUT WHAT PROCESS IS ACCELERATED IN THE MYOCARDIUM WHEN INTRODUCING THIS DRUG... BUT ONLY IF ALL METABOLIC PROCESSES ACCELERATE AND THE ACTIVITY OF THE HEART IS RESTORED...

59 It is known that Hg 2+ binds irreversibly to the SH groups of lipoic acid. What changes in energy metabolism can lead to chronic mercury poisoning?

Answer: By modern ideas mercury and especially organic mercury compounds are enzymatic poisons, which, when entering the blood and tissues even in minute quantities, exhibit their toxic effect there. The toxicity of enzyme poisons is due to their interaction with the thiol sulfhydryl groups (SH) of cellular proteins, in this case lipoic acid which participates in the redox processes of the tricarboxylic acid cycle (Krebs cycle) as a coenzyme, optimizing oxidative phosphorylation reactions, lipoic acid also plays important role in the utilization of carbohydrates and the implementation of normal energy metabolism, improving the “energy status” of the cell. As a result of this interaction, the activity of the main enzymes is disrupted. normal functioning which require the presence of free sulfhydryl groups. Mercury vapor, entering the blood, first circulates in the body in the form of atomic mercury, but then the mercury undergoes enzymatic oxidation and enters into compounds with protein molecules, interacting primarily with the sulfhydryl groups of these molecules. Mercury ions primarily affect numerous enzymes, and, above all, thiol enzymes, which play a major role in metabolism in a living organism, as a result of which many functions are disrupted, especially the nervous system. Therefore, with mercury intoxication, nervous system disorders are the first signs indicating harmful effects mercury

Shifts in such vital important organs, as the nervous system, are associated with disorders of tissue metabolism, which in turn leads to disruption of the functioning of many organs and systems, manifested in various clinical forms intoxication.

60. How will a deficiency of vitamins PP, B1, B2 affect the body’s energy metabolism? Explain your answer. What enzymes require these vitamins to “work”?

Answer: The cause of a hypoenergetic state may be hypovitaminosis, since in reactions Vit PP is integral part coenzymes; Suffice it to say that a number of coenzyme groups that catalyze tissue respiration include nicotinic acid amide. The absence of nicotinic acid in food leads to disruption of the synthesis of enzymes that catalyze redox reactions (oxidoreductases: alcohol dehydrogenase)), and leads to disruption of the oxidation mechanism of certain substrates of tissue respiration. Vitamin PP ( a nicotinic acid) is also part of the enzymes involved in cellular respiration and digestion. Nicotinic acid is amidated in tissues, then combines with ribose, phosphoric and adenylic acids, forming coenzymes, and the latter, with specific proteins, form dehydrogenase enzymes involved in numerous oxidative reactions in the body. Vitamin B1 – essential vitamin in energy metabolism, important for maintaining mitochondrial activity. In general, it normalizes the activity of the central, peripheral nervous systems, cardiovascular and endocrine systems. Vitamin B1, being a coenzyme of decarboxylases, is involved in the oxidative decarboxylation of keto acids (pyruvic, α-ketoglutaric), is an inhibitor of the enzyme cholinesterase, which breaks down the CNS transmitter acetylcholine, and is involved in the control of Na+ transport across the neuron membrane.

It has been proven that vitamin B1 in the form of thiamine pyrophosphate is a component of at least four enzymes involved in intermediate metabolism. These are two complex enzyme systems: pyruvate and α-ketoglutarate dehydrogenase complexes, catalyzing the oxidative decarboxylation of pyruvic and α-ketoglutaric acids (enzymes: pyruvate dehydrogenase, α-ketoglutarate dehydrogenase). vitamin B2 in combination with proteins and phosphoric acid in the presence of microelements, such as magnesium, it creates enzymes necessary for the metabolism of saccharides or for the transport of oxygen, and therefore for the respiration of every cell of our body. Vitamin B2 is necessary for the synthesis of serotonin, acetylcholine and norepinephrine, which are neurotransmitters, as well as histamine, which released from cells during inflammation. In addition, riboflavin is involved in the synthesis of three essential fatty acids: linoleic, linolenic and arachidonic. Riboflavin is necessary for the normal metabolism of the amino acid tryptophan, which is converted in the body into niacin.

Vitamin B2 deficiency can cause a decrease in the ability to produce antibodies, which increase resistance to disease.

1. All leaves have veins. What structures are they formed from? What is their role in the transport of substances throughout the plant?

The veins are formed by vascular-fibrous bundles that penetrate the entire plant, connecting its parts - shoots, roots, flowers and fruits. They are based on conductive tissues, which carry out the active movement of substances, and mechanical ones. Water and minerals dissolved in it move in the plant from the roots to the above-ground parts through the vessels of the wood, and organic substances move through the sieve tubes of the bast from the leaves to other parts of the plant.

In addition to conductive tissue, the vein contains mechanical tissue: fibers that give the leaf plate strength and elasticity.

2. What is the role of the circulatory system?

Blood is carried throughout the body nutrients and oxygen, removes carbon dioxide and other decay products. Thus the blood performs respiratory function. White blood cells perform protective function: They destroy pathogens that have entered the body.

3. What does blood consist of?

Blood consists of a colorless liquid - plasma and blood cells. There are red and white blood cells. Red blood cells give blood its red color because they contain a special substance - the pigment hemoglobin.

4. Offer simple circuits closed and open circulatory systems. Point out the heart, blood vessels and body cavity.

Scheme of an open circulatory system

5. Offer an experiment that proves the movement of substances throughout the body.

Let us prove that substances move throughout the body using the example of a plant. Let's put a young shoot of a tree in water tinted with red ink. After 2-4 days, take the shoot out of the water, wash off the ink from it and cut off a piece of the lower part. Let us first consider a cross section of the shoot. The cut shows that the wood has turned red.

Then we cut along the rest of the shoot. Red stripes appeared in areas of stained vessels that are part of the wood.

6. Gardeners propagate some plants using cut branches. They plant the branches in the ground and cover them with a jar until they are completely rooted. Explain the meaning of the jar.

Under the can, high constant humidity is formed due to evaporation. Therefore, the plant evaporates less moisture and does not wither.

7. Why do cut flowers fade sooner or later? How can you prevent their rapid decline? Make a diagram of the transport of substances in cut flowers.

Cut flowers are not a full-fledged plant, because they have had the horse system removed, which ensured adequate (as intended by nature) absorption of water and minerals, as well as part of the leaves that provided photosynthesis.

The flower withers mainly because there is not enough moisture in the cut plant or flower due to increased evaporation. This begins from the moment of cutting and especially when the flower and leaves have been without water for a long time and have a large evaporation surface (cut lilac, cut hydrangea). Many greenhouse cut flowers find it difficult to tolerate the difference between the temperature and humidity of the place where they were grown and the dryness and warmth of living rooms.

But a flower can fade or grow old, this process is natural and irreversible.

To avoid fading and extend the life of flowers, a bouquet of flowers should be in a special package that serves to protect against crushing, penetration sun rays, warmth of hands. On the street, it is advisable to carry the bouquet with the flowers facing down (moisture will always flow directly to the buds while the flowers are being transferred).

One of the main reasons for flowers wilting in a vase is a decrease in the sugar content in the tissues and dehydration of the plant. This happens most often due to blockage of blood vessels by air bubbles. To avoid this, the end of the stem is immersed in water and an oblique cut is made with a sharp knife or pruning shears. After this, the flower is no longer removed from the water. If such a need arises, the operation is repeated again.

Before placing cut flowers in water, remove all lower leaves from the stems, and also remove thorns from roses. This will reduce the evaporation of moisture and prevent the rapid development of bacteria in the water.

8. What is the role of root hairs? What is root pressure?

Water enters the plant through root hairs. Covered with mucus, in close contact with the soil, they absorb water with minerals dissolved in it.

Root pressure is the force that causes one-way movement of water from roots to shoots.

9. What is the significance of water evaporation from leaves?

Once in the leaves, water evaporates from the surface of the cells and exits into the atmosphere in the form of steam through the stomata. This process ensures a continuous upward flow of water through the plant: having given up water, the cells of the leaf pulp, like a pump, begin to intensively absorb it from the vessels surrounding them, where water enters through the stem from the root.

10. In the spring, the gardener discovered two damaged trees. In one, mice partially damaged the bark; in another, hares gnawed a ring on the trunk. Which tree can die?

A tree whose trunk has been gnawed by hares may die. As a result, it will be destroyed inner layer bark, which is called bast. Solutions move through it organic matter. Without their influx, cells below the damage will die.

The cambium lies between the bark and wood. In spring and summer, the cambium divides vigorously, resulting in new phloem cells being deposited toward the bark and new wood cells toward the wood. Therefore, the life of the tree will depend on whether the cambium is damaged.