Stoma. Stomata in a plant: definition, location, functions

The number of stomata and their placement in different plant species vary greatly. In xerophytes, i.e., in forms adapted to living in arid regions, there are usually fewer stomata per unit surface than in mesophytes; in addition, their stomata are sometimes located in the recesses of the strongly cutinized surface of the leaves or stem, which also reduces water loss, since it limits turbulence in the air layer adjacent to the stomata (Fig. 4.2 and 6.11). Most plants have stomata on both sides of the leaf - upper and lower; there are, however, those species in which the stomata are located only on the underside of the leaves. The number of stomata per 1 cm 2 of the leaf surface exceeds 60,000 in cucumber, and in some cereals it does not even reach 8000. Even on the same plant, leaves can vary greatly both in number and in the location of stomata; in "shady" leaves, for example, the number of stomata per unit surface is usually less than in "light" ones. According to estimates made for a variety of plants, fully open stomata occupy 1-3% of the entire leaf area, while the diffusion of water vapor from the leaf occurs with open stomata at almost the same rate as from the free surface (Fig. 6.12). It is this circumstance that explains the fact that under conditions of good moisture, in bright light and at high temperatures, plants lose a huge amount of water.

The intensity of transpiration, i.e., the evaporation of water by the aerial parts of plants (Fig. 6.13), depends on the width of the stomatal gaps, on the difference in the water potentials of the air inside and outside the leaf, and on air turbulence. The less humid the atmospheric air, the lower (more negative) its water potential. (Water vapor pressure and relative humidity, which also measure the amount of moisture in atmospheric air, are also lower.) When air is saturated with moisture, its water potential is zero. With a decrease in the relative humidity of the air by only 1-2%, the water potential drops very sharply. When the relative humidity decreases to about 50%, the water potential of the atmospheric air is already expressed as a negative value of the order of several hundred bar. In leaf cells, the water potential is rarely below -20 bar, and therefore water from the intercellular spaces (in which the air is half saturated with it, and the water potential is balanced with the water potential of the surrounding cells) quickly diffuses into drier atmospheric air. Water molecules leave the plant, obeying the same law that governs their movement inside the plant, i.e. moving in the direction of decreasing water potential (Table 6.2).

On a sunny day, the temperature inside the leaf can be up to 10°C higher than in the surrounding air. Due to this temperature difference, transpiration increases, since the air inside the leaf is saturated with moisture, and the saturation vapor pressure increases with increasing temperature. Air turbulence also promotes transpiration, since the rapid removal of water vapor from the air layer adjacent to the leaf increases the diffusion gradient (and hence the rate of diffusion) from the leaf into the atmosphere. Therefore, on dry windy sunny days, especially during dry periods, water often evaporates from the plant faster than the roots can supply it. When the loss of water from the leaves for a long time exceeds its intake through the roots, the plant wilts. On a hot summer day, transpiration often outweighs water uptake, even if there is enough water in the soil; under such conditions, the leaves of all kinds of plants and the stems of herbaceous plants often become slightly wilted in the afternoon hours. Toward evening, transpiration weakens and the plants begin to recover from wilting. During the night, the water deficit in leaf cells decreases as the roots of the plant suck up water from the soil; this continues until the leaf cells fully restore their turgor - usually by morning all signs of wilting disappear. This daily temporary wilting, the so-called diurnal wilting, is a quite common phenomenon; it does not harm the plant, except for some weakening of photosynthesis due to the closing of the stomata. Another thing is when the plant does not receive moisture from the soil for a long time; under these conditions, temporary wilting turns into long-term, and if this continues for a long time, then the plant dies.

Regulation of stomatal guard cell movements

It has long been known that the width of the stomatal fissures (the opening of the stomata) is determined by the turgor of the guard cells of the stomata, as already mentioned in Chap. 2. However, only recently, in the last decade, it became clear that the turgor of these cells depends mainly on the content of potassium salts. At night, the concentration of dissolved substances in the vacuoles of guard cells is relatively low; in accordance with this, ψ ; π is large, the cells are sluggish and the stomatal opening is closed. At dawn, potassium ions begin to flow from neighboring cells into the vacuoles of guard cells. This process is often accompanied by the breakdown of starch and the accumulation of malic acid. As a result, ψπ sharply decreases, water absorption begins, the guard cells, which have very elastic, unevenly thickened walls, swell and bend in such a way that the stomatal fissure opens. The release of K + ions from guard cells at the end of the day or with a lack of water leads to a reduction in the volume of guard cells, as a result of which the stomata close (Fig. 6.14). The peristomatal cells of the epidermis serve as a reservoir in which K+ ions are stored while the stomata are closed. Any change in the size of these peristomatal cells is always opposite in sign to the simultaneous change in the guard cells and promotes either the opening or closing of the stomata.

Rice. 6.14. Distribution of potassium in the cells of the stomatal complex Vicia fab a with closed (A) and open (B) stomata. (Humble, Raschke. 1971. Plant Physiol., 48, 447-459.) The K content in stripped pieces of leaf epidermis was determined by the electron microprobe method. To do this, pieces of the epidermis were quickly frozen in liquid nitrogen and dried in a frozen state. This method was used instead of chemical fixation because potassium is soluble in most chemical fixatives. The device creates a high-energy electron beam, which, being focused on the tissue, excites x-rays in it. White spots in the lower micrographs (C and D) correspond to the X-ray emission of K atoms; white areas in the upper photomicrographs, due to electron backscattering, reveal tissue morphology. Note that K + ions concentrated in adjacent (peri-stomatal) cells, when the stomata are closed, pass into the guard cells when the stomata open.

When any positively charged ions, such as K + ions, pass through the cell membrane, the electrical neutrality of the cell is maintained due to the simultaneous movement of other charged particles: either negatively charged anions move in the same direction as K +, or H + ions must move in the opposite direction. direction (see Ch. 7). It is now known that in some plants an important role in the regulation of guard cell turgor is played by the movement of chloride ions (Cl -), while in other plants, apparently, some other mechanism operates. In maize (Zea mays), about 40% of K + ions enter or exit guard cells accompanied by Cl - ions. There are plants in which the participation of Cl ions is relatively small and some other ions can perform their function. A similar replacement is sometimes observed in those plants in which Cl - ions normally play this role. The intensive movement of H+ ions through the membranes of guard cells in the direction opposite to the movement of K+ ions is apparently characteristic of all plants. Indeed, the opening of stomata is accompanied by a noticeable increase in intracellular pH, which, of course, is to be expected when H+ ions leave the cell. Organic acids present in the vacuolar sap may well be the source of H+ ions, since their content in the vacuolar sap increases when the stomata open.

External factors regulating stomatal movements

When a plant experiences a lack of water, the stomatal guard cells become lethargic and the stomatal openings close, preventing further water loss. Until recently, this was seen as the main mechanism that allows the plant to avoid excessively strong wilting. It turned out, however, that plants have another, faster and more efficient way to suppress transpiration. In the early stages of water deficiency in many plants, the content of one of the hormones, namely abscisic acid (ABA) increases sharply (see Chap. 10). Somehow this leads to an outflow of K+ from the guard cells and, as a consequence, to water loss and stomata closure. Elegant experiments demonstrating this effect were carried out with the so-called wilty mutant of tomato, obtained by chance in experiments with X-ray irradiation of the seeds of one of the usual varieties. This mutant is distinguished by the fact that it quickly withers even with the slightest lack of water, because its stomata are always open. It was found that this mutant has a sharply reduced content of ABA, it is 10 times lower than that of the parent variety. When mutant plants were treated with ABA, their stomata began to close and turgor recovered faster. Obviously, in this variety of tomato, stomatal closure is regulated either by abscisic acid itself or by some product of its metabolic transformations. Later it turned out that treatment with small doses of ABA can cause stomatal closure in other plants as well. It was also found that with a lack of water, the content of endogenous ABA increases, after which the stomata close. Thus, one of the important physiological functions of the hormone ABA is apparently the protection of plants from desiccation. Other regulatory functions of this hormone are discussed in Chap. 10.

Given the importance of the opening and closing of stomata in the life of a plant, one should not be surprised that the movements of stomata are regulated not only by the water supply of plants, but also by some other environmental factors. In many plants, for example, the opening of stomata depends primarily on the content of CO 2 in the air filling the substomatal air cavity. If the concentration of CO 2 falls below 0.03% there, i.e., below the level normal for atmospheric air, then the turgor of guard cells increases and the stomata open. Typically, illumination of the guard cells leads to this result, stimulating photosynthetic activity in them, as a result of which the CO 2 content in the adjacent air-filled cavities decreases. Stomatal opening can also be induced artificially by removing CO 2 from the air, and closing by increasing the concentration of CO 2 in the air. This regulation of stomatal movements by CO 2 makes it possible to understand why stomata are usually open during the day and closed at night.

The opening of stomata by light can be partly explained by the fact that photosynthesis reduces the concentration of CO 2 in the leaf. However, light also has another, more direct effect. The protoplasts of the onion guard cells, which do not contain chloroplasts, swell when illuminated with blue light, but this effect is manifested only if potassium salts are present in the medium. The blue light absorbing pigment that stimulates the influx of K + ions and the increase in turgor is, presumably, the flavoprotein described in Chap. eleven.

Rice. 6.15. Daily course of stomatal movements (I) and water uptake (II). (Amended from Mansfield T. 1971. J. Biol. Educ., 5, 115-123.) a. Closing of the stomata is associated with the absence of light, the accumulation of CO 2 during respiration and the phase of the endogenous rhythm, b. Before dawn, the stomata begin to open because the endogenous rhythm (opening phase) prevails over other factors. In mesophytes, this "night opening" is weakly expressed; in Crassulaceae, however, it is much stronger due to the depletion of CO 2 as a result of dark fixation, c. Full opening is a direct result of light and CO 2 depletion during photosynthesis, d. Partial closing in the afternoon can be explained by both an endogenous rhythm (transition to the closing phase) and a decrease in light, e. The stomata of some plant species close at noon, if the temperature is too high and transpiration exceeds water uptake. This closure is probably regulated by abscisic acid, under the influence of which the stomata close during periods of lack of water. e. Closing of stomata under the influence of the endogenous rhythm increases due to the absence of light and under the influence of CO 2 accumulated during respiration. Daily fluctuations in water loss are similar to the daily course of stomata opening. Water absorption lags somewhat behind transpiration due to the resistance that water encounters on its way through the plant. As a result, a certain deficiency develops during the daytime, which is then eliminated at night due to the prolonged absorption of water.

Typically, the rate of transpiration varies in some way throughout the day. At first, at dawn, it increases quite sharply and, continuing to increase, reaches a maximum by noon. Thereafter, if the temperature is too high, there is a slight drop followed by a slight rise corresponding to a drop in temperature. Fluctuations in the intensity of transpiration reflect changes in the state of the stomatal openings. The closing of the stomata at noon is partly due to the high concentration of CO 2 inside the leaf, which is typical for this time of day. The level of CO 2 in a leaf depends on the ratio of respiration and photosynthesis rates, and the rate of respiration increases quite rapidly with increasing temperature, while the process of photosynthesis is less sensitive to temperature. In addition to this, the closing of the stomata at noon is probably facilitated by the fact that at this time, due to the lack of water in the leaf, the concentration of abscisic acid increases.

So, we have seen that stomatal movements are regulated by the main environmental factors: light, temperature, soil moisture content, air humidity and CO 2 concentration in the air; all of these variables affect internal factors such as water content and the concentration of abscisic acid in the leaf. In addition, there are also rhythmic fluctuations in the opening of the stomata, which occur even in the absence of external influences. These rhythmic fluctuations are regulated by an internal oscillator - the plant's biological clock, which we will discuss in Chap. 12. Fig. 6.15 illustrates the daily course of stomatal movements, regulated by internal rhythms and external factors together.

Who published this discovery in 1675 in his work Anatome plantarum. However, he did not understand their true function. At the same time, his contemporary Nehemiah Grew developed the hypothesis of the participation of stomata in the ventilation of the internal environment of the plant and compared them with insect tracheae. Progress in the study came in the 19th century, and at the same time, in 1827, the word "stoma" was first used by the Swiss botanist Decandole. The study of stomata at that time was carried out by Hugo von Mol, who discovered the basic principle of opening stomata, and Simon Schwendener, who classified stomata by the type of their construction.

Some aspects of the functioning of stomata continue to be intensively studied at the present time; The material is mainly Commelina vulgaris ( Commelina communis), garden bob ( Vicia faba), Sweet corn ( Zea mays).

Structure

The size of the stomata (length) ranges from 0.01-0.06 mm (the stomata of polyploid plants are also larger in leaves growing in the shade. The largest stomata were found in an extinct plant Zosterophyllum, 0.12 mm (120 µm) Pore consists of a pair of specialized cells called guard cells (cellulae claudentes), which regulate the degree of openness of the pore, between them is the stomatal gap (porus stomatalis). The walls of the guard cells are thickened unevenly: those directed towards the gap (abdominal) are thicker than the walls directed away from the gap (dorsal). The gap can expand and narrow, regulating transpiration and gas exchange. When there is little water, the guard cells are tightly adjacent to each other and the stomatal opening is closed. When there is a lot of water in the guard cells, it presses on the walls and the thinner walls stretch more, and the thicker ones are drawn inward, a gap appears between the guard cells. Under the gap there is a substomatal (air) cavity, surrounded by cells of the pulp of the leaf, through which gas exchange takes place directly. Air containing carbon dioxide (carbon dioxide) and oxygen penetrates into the leaf tissue through these pores, and is further used in the process of photosynthesis and respiration. Excess oxygen produced during photosynthesis by the inner cells of the leaf is released back into the environment through the same pores. Also, in the process of evaporation, water vapor is released through the pores. Epidermal cells adjacent to the trailing cells are called accompanying (side, neighboring, parotid). They are involved in the movement of guard cells. Trailing and accompanying cells form a stomatal complex (stomatal apparatus). The presence or absence of stomata (the visible parts of the stomata are called stomatal lines) is often used in the classification of plants.

Stomata types

The number of accompanying cells and their location relative to the stomatal opening make it possible to distinguish a number of types of stomata:

anomocytic - accompanying cells do not differ from the rest of the cells of the epidermis, the type is very common for all groups of higher plants, with the exception of conifers;
diacytic - characterized by only two accompanying cells, the common wall of which is at right angles to the trailing cells;
paracytic - accompanying cells are located parallel to the closing and stomatal gaps;
anisocytic - guard cells are surrounded by three accompanying cells, one of which is noticeably larger or smaller than the others, this type is found only in flowering plants;
tetracytic - four accompanying cells, characteristic of monocots;
encyclocytic - accompanying cells form a narrow wheel around guard cells;
actinocytic - several accompanying cells, radially diverging from the trailing cells;
pericytic - the guard cells are surrounded by one secondary accompanying cell, the stomata is not connected to the accompanying cell by an anticlinal cell wall;
desmocytic - guard cells are surrounded by one accompanying cell, the stomata are connected to it by an anticlinal cell wall;
polocytic - guard cells are not completely surrounded by one accompanying one: one or two epidermal cells adjoin one of the stomatal poles; the stoma is attached to the distal side of a single accompanying cell, which is U-shaped or horseshoe-shaped;
stephanocyte - a stomata surrounded by four or more (usually five to seven) poorly differentiated accompanying cells, forming a more or less distinct rosette;
laterocyte - this type of stomatal apparatus is considered by most botanists as a simple modification of the anomocytic type.

In dicots, the paracytic type of stomata is common. The trailing cells of a kidney-shaped (bean-shaped) shape - as they are visible from the surface of the leaf - carry chloroplasts, thin, unthickened sections of the membrane form protrusions (spouts) covering the stomatal gap.

The outer walls of the guard cells usually have outgrowths, which is clearly seen in the transverse section of the stomata. The space bounded by these outgrowths is called the front yard. Quite often, similar outgrowths are observed in the inner membranes of guard cells. They form a backyard, or inner courtyard, connected to a large intercellular space - the substomatal cavity.

In monocots, the paracytic structure of stomata was noted in cereals. The guard cells are dumbbell-shaped - narrowed in the middle part and expanded at both ends, while the walls of the expanded areas are very thin, and in the middle part of the guard cells they are very thickened. Chloroplasts are located in the vesicular endings of cells.

Guard cell movement

The mechanism of movement of guard cells is very complex and varies in different species. In most plants, with unequal water supply at night, and sometimes during the day, the turgor in guard cells decreases, and the stomatal gap closes, thereby reducing the level of transpiration. With an increase in turgor, the stomata open. It is believed that the main role in the change in turgor belongs to potassium ions. The presence of chloroplasts in the guard cells is essential in the regulation of turgor. The primary starch of chloroplasts, turning into sugar, increases the concentration of cell sap. This contributes to the influx of water from neighboring cells and an increase in turgor pressure in guard cells.

Location of stomata

Dicotyledonous plants tend to have more stomata at the bottom of the leaf than at the top. This is due to the fact that the upper part of a horizontally arranged leaf, as a rule, is better lit, and a smaller number of stomata in it prevents excessive evaporation of water. Leaves with stomata located on the underside are called hypostomatic.

In monocot plants, the presence of stomata in the upper and lower parts of the leaf is different. Very often the leaves of monocotyledonous plants are arranged vertically, in which case the number of stomata on both parts of the leaf may be the same. Such leaves are called amphistomatic.

Floating leaves on the underside of the leaf lack stomata, as they can absorb water through the cuticle. Leaves with stomata located on the upper side are called epistomatic. Underwater leaves have no stomata at all.

The stomata of coniferous plants are usually hidden deep under the endodermis, which makes it possible to greatly reduce water consumption in winter for evaporation, and in summer during drought.

Mosses (with the exception of anthocerotes) have no true stomata.

Stomata also differ in their level of location relative to the surface of the epidermis. Some of them are located flush with other epidermal cells, others are raised above or immersed below the surface. In monocots, whose leaves grow predominantly in length, the stomata form regular parallel rows, while in dicots they are arranged randomly.

Carbon dioxide

Since carbon dioxide is one of the key reactants in the process of photosynthesis, most plants have stomata open during the daytime. The problem is that when the air enters, it mixes with the water vapor evaporating from the leaf, and so the plant cannot get carbon dioxide without losing some water at the same time. Many plants have protection against water evaporation in the form of wax deposits that clog their stomata.

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Notes

Literature

// Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
Atlas of plant anatomy: textbook. manual for universities / Bavtuto G. A., Eremin V. M., Zhigar M. P. - Mn. : Urajay, 2001. - 146 p. - (Study and textbooks for universities). - ISBN 985-04-0317-9.
Colin Michael Willmer, Mark Fricker. Stomata. - Chapman & Hall, 1995. - ISBN 0412574306.

Footnotes

An excerpt characterizing the Stoma

“This is Bezukhova’s brother, Anatole Kuragin,” she said, pointing to the handsome cavalry guard, who walked past them, looking somewhere from the height of his raised head through the ladies. - How good! is not it? They say they will marry him to this rich woman. .And your sousin, Drubetskoy, is also very entangled. They say millions. “Well, it’s the French envoy himself,” she answered about Caulaincourt when asked by the countess who it was. “Look like some kind of king. And yet the French are very, very nice. There is no mile for society. And here she is! No, everything is better than all our Marya Antonovna! And how simply dressed. Charm! “And this one, fat, with glasses, is a worldwide freemason,” said Peronskaya, pointing to Bezukhov. - With his wife, then put him next to him: then that jester of peas!
Pierre walked, waddling his fat body, pushing the crowd apart, nodding right and left as casually and good-naturedly as if he were walking through the crowd of a bazaar. He moved through the crowd, apparently looking for someone.
Natasha looked with joy at the familiar face of Pierre, that pea jester, as Peronskaya called him, and knew that Pierre was looking for them, and especially for her, in the crowd. Pierre promised her to be at the ball and introduce her to the gentlemen.
But, before reaching them, Bezukhoy stopped beside a short, very handsome brunette in a white uniform, who, standing at the window, was talking to some tall man in stars and a ribbon. Natasha immediately recognized a short young man in a white uniform: it was Bolkonsky, who seemed to her very rejuvenated, cheerful and prettier.
- Here's another friend, Bolkonsky, see, mom? - said Natasha, pointing to Prince Andrei. - Remember, he spent the night with us in Otradnoye.
– Oh, you know him? Peronskaya said. - Hate. Il fait a present la pluie et le beau temps. [It now determines rainy or fine weather. (French proverb, meaning that he is successful.)] And such pride that there are no borders! I followed papa. And he contacted Speransky, some projects are being written. See how the ladies are treated! She's talking to him, and he's turned away,” she said, pointing at him. “I would beat him up if he did the same to me as he did to these ladies.

Suddenly everything stirred, the crowd began to talk, moved, parted again, and between the two parted rows, at the sound of music playing, the sovereign entered. Behind him were the owner and mistress. The emperor walked quickly, bowing to the right and left, as if trying to get rid of this first minute of the meeting as soon as possible. The musicians played Polish, known then for the words composed on it. These words began: “Alexander, Elizabeth, you delight us ...” The sovereign went into the living room, the crowd rushed to the doors; several faces with changed expressions hurried back and forth. The crowd again retreated from the doors of the drawing room, in which the sovereign appeared, talking with the hostess. Some young man with a confused look was advancing on the ladies, asking them to step aside. Some ladies with faces expressing complete forgetfulness of all the conditions of the world, spoiling their toilets, crowded forward. Men began to approach the ladies and line up in Polish pairs.
Everything parted, and the emperor, smiling and out of time leading the mistress of the house by the hand, went out of the doors of the drawing room. He was followed by the owner with M.A. Naryshkina, then envoys, ministers, various generals, whom Peronskaya called incessantly. More than half of the ladies had cavaliers and were walking or preparing to go to Polskaya. Natasha felt that she remained with her mother and Sonya among the smaller part of the ladies pushed back to the wall and not taken in Polskaya. She stood with her slender arms lowered, and with a measuredly rising, slightly defined chest, holding her breath, with shining, frightened eyes, she looked ahead of her, with an expression of readiness for the greatest joy and the greatest grief. She was not interested in either the sovereign or all the important persons that Peronskaya pointed out - she had one thought: “is it really that no one will come up to me, really I won’t dance between the first, really all these men who now, it seems that they don’t see me, but if they look at me, they look with such an expression, as if they say: Ah! it's not her, so there's nothing to see. No, it can't be!" she thought. “They must know how I want to dance, how well I dance, and how fun it will be for them to dance with me.”
The sounds of Polish, which had gone on for quite some time, were already beginning to sound sad, a memory in Natasha's ears. She wanted to cry. Peronskaya moved away from them. The count was at the other end of the hall, the countess, Sonya and she stood alone as if in a forest in this alien crowd, uninteresting and unnecessary to anyone. Prince Andrei walked past them with some lady, apparently not recognizing them. The handsome Anatole, smiling, said something to the lady he was leading, and looked at Natasha's face with the look with which they look at the walls. Boris walked past them twice and each time turned away. Berg and his wife, who were not dancing, approached them.
This family rapprochement here, at the ball, seemed insulting to Natasha, as if there was no other place for family conversations except at the ball. She did not listen and did not look at Vera, who was saying something to her about her green dress.
Finally, the sovereign stopped beside his last lady (he was dancing with three), the music stopped; the preoccupied adjutant ran up to the Rostovs, asking them to move somewhere else, although they were standing against the wall, and the distinct, cautious and fascinatingly measured sounds of a waltz rang out from the choir. The emperor looked at the hall with a smile. A minute passed and no one started yet. The adjutant manager approached Countess Bezukhova and invited her. She raised her hand, smiling, and laid it, without looking at him, on the adjutant's shoulder. The adjutant manager, a master of his craft, confidently, leisurely and measuredly, tightly embracing his lady, first set off with her on a glide path, along the edge of the circle, at the corner of the hall, grabbed her left hand, turned her, and because of the ever faster sounds of music, only measured the clicks of the spurs of the aide-de-camp's quick and agile feet, and every three beats at the turn, the fluttering velvet dress of his lady seemed to flare up. Natasha looked at them and was ready to cry that it was not she who was dancing this first round of the waltz.
Prince Andrei, in his colonel's white (for cavalry) uniform, in stockings and boots, lively and cheerful, stood in the forefront of the circle, not far from the Rostovs. Baron Firgof spoke to him about tomorrow, the proposed first meeting of the State Council. Prince Andrei, as a person close to Speransky and participating in the work of the legislative commission, could give correct information about the meeting of tomorrow, about which there were various rumors. But he did not listen to what Firgof told him, and looked first at the sovereign, then at the gentlemen who were about to dance, who did not dare to enter the circle.
Prince Andrei watched these cavaliers and ladies, timid in the presence of the sovereign, dying from the desire to be invited.
Pierre went up to Prince Andrei and grabbed his hand.
- You always dance. Here is my protegee [favorite], young Rostova, invite her, - he said.
- Where? Bolkonsky asked. “I’m sorry,” he said, turning to the baron, “we will finish this conversation in another place, but at the ball we have to dance.” - He stepped forward, in the direction that Pierre indicated to him. Natasha's desperate, fading face caught Prince Andrei's eyes. He recognized her, guessed her feelings, realized that she was a beginner, remembered her conversation at the window, and with a cheerful expression approached Countess Rostova.
“Let me introduce you to my daughter,” said the countess, blushing.
“I have the pleasure of being acquainted, if the countess remembers me,” said Prince Andrei with a courteous and low bow, completely contradicting Peronskaya’s remarks about his rudeness, going up to Natasha, and raising his hand to hug her waist even before he finished the invitation to dance. He suggested a waltz tour. That fading expression on Natasha's face, ready for despair and delight, suddenly lit up with a happy, grateful, childish smile.
“I have been waiting for you for a long time,” as if this frightened and happy girl said, with her smile that appeared from ready tears, raising her hand on Prince Andrei’s shoulder. They were the second couple to enter the circle. Prince Andrei was one of the best dancers of his time. Natasha danced superbly. Her feet in ballroom satin shoes quickly, easily and independently of her did their job, and her face shone with the delight of happiness. Her bare neck and arms were thin and ugly. Compared to Helen's shoulders, her shoulders were thin, her chest indefinite, her arms thin; but Helen already seemed to have varnish from all the thousands of glances that glided over her body, and Natasha seemed like a girl who was naked for the first time, and who would be very ashamed of it if she had not been assured that it was so necessary.
Prince Andrei loved to dance, and wanting to quickly get rid of the political and intelligent conversations with which everyone turned to him, and wanting to quickly break this annoying circle of embarrassment formed by the presence of the sovereign, he went to dance and chose Natasha, because Pierre pointed her out to him. and because she was the first of the pretty women that caught his eye; but as soon as he embraced this thin, mobile body, and she stirred so close to him and smiled so close to him, the wine of her charms hit him in the head: he felt revived and rejuvenated when, catching his breath and leaving her, he stopped and began to look on the dancers.

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In a flowering plant, the following organs are distinguished: root, stem, leaf, flower, fruit with seeds. Select the characteristics that correspond to the structural features of the flower as a plant organ according to the following plan: definition of the organ, growth of the organ, location of the growth point, main functions and participation of the organ in the nutrition of the plant.

A. Definition of a plant organ
1) a lateral vegetative organ, which, as a rule, has bilateral symmetry
2) a reproductive organ that develops with the growth of the ovary of the pistil after pollination
3) modified generative escape
4) axial vegetative aboveground organ that carries the kidneys
5) axial vegetative underground organ

B. Organ growth
1) growth of the organ continues throughout the life of the plant
2) the growth of the organ continues for a certain time, after which it stops

B. Location of points of growth
1) the organ is characterized by growth by the base
2) the organ is characterized by apical growth
3) the organ grows due to the division of all cells

D. Organ functions
1) provides photosynthesis, evaporation, gas exchange
2) connects the aboveground and underground parts of the plant
3) strengthens the plant in the soil
4) participates in pollination, fertilization, seed development
5) serves to preserve and distribute seeds

D. Participation of the organ in the nutrition of the plant
1) only stores nutrients
2) provides the plant with water with dissolved minerals
3) does not provide the plant with nutrients, but only uses them for its own growth
4) carries out the synthesis of organic substances from carbon dioxide and water
5) provides the movement of mineral and organic substances, and sometimes stores them

Answer: A B C D D

Number of eggs in clutch	Percentage of surviving chicks (in %)
1	100
2	95
3	90
4	83
5	80
6	53
7	40
8	35
9	32

1) What is the relationship between the number of eggs in a clutch and the proportion of surviving chicks?
2) What is the percentage of chicks that have flown out of the nest with a clutch size of 5?
3) How can one explain that there are a small number of eggs in the clutch of a starling?

1) fruit
2) inflorescence
3) flower
4) fruiting body

Which organ is missing in sharks and rays?
1) intestines
2) gills
3) gill slits
4) swim bladder

Establish a correspondence between the animal and the number of chambers of its heart: for each element of the first column, select the corresponding element from the second column.

ANIMAL
A) a whale
B) already
B) crocodile
D) sparrow
D) frog
E) triton

NUMBER OF HEART CHAMBER
1) four
2) three

1) formation of trachea and spiracles
2) the formation of a three-chambered heart, in the ventricle of which there is an incomplete septum
3) the development of cubs in the uterus of the female
4) development of the nervous system of the nodal type
5) the appearance of paired lungs Answer: 41523 Incorrectly designed test. The answer will look like this: 1 then 5, if the word “lungs” means only the lungs that appeared in vertebrates (not taking into account paired lung sacs or “lights” in arachnids). But maybe the authors-compilers had conceived the answer 5 (light arachnids) then 1.

A specialized organ of air nutrition of a plant is
1) green leaf
2) root crop
3) flower
4) fruit

Modern lobe-finned fish include
1) shark
2) stingray
3) sturgeon
4) coelacanth

What common property unites the two depicted anatomical formations? Both of them are

1) the roots of living plants
2) solid particles of soil
3) insect larvae
4) plant residues

In the table below, there is a relationship between the positions of the first and second columns.

What concept should be entered in place of the gap in this table?
1) pedicel
2) gametophyte
3) fruiting body
4) sprout

What mollusks lead a terrestrial lifestyle?
1) toothless
2) slugs
3) barley
4) squid

The tuber is a modified shoot, this proves the presence on the tuber
1) membranous scales
2) buds-eyes
3) fleshy and juicy scales
4) flat stem - bottom

What animal is shown in the picture?

1) green euglena
2) infusoria shoe
3) common amoeba
4) malarial plasmodium

The figure shows light and dark moth butterflies on a birch trunk. As part of the experiment, light and dark butterflies were released into an isolated area of a birch forest in a ratio of 1: 1. How will the ratio of the number of light and black butterflies change over several years if there was an unregulated emission of soot and burning particles by enterprises?

3) the ratio of light and dark butterflies will not change

In fact, the dark pine trunk is clearly visible in the figure (the characteristic structure of the bark, and not the alternation of white and dark areas on the birch trunk). But in any case, with prolonged pollution of the trunks with soot, dark-colored butterflies will be less noticeable for pecking by birds.

Establish a correspondence between the characteristic of the plant and the department for which it is characteristic: for each element of the first column, select the corresponding element from the second column.

PLANT SIGN
A) there is a germ in the development cycle
B) the sporangium on the plant looks like a box
C) a green thread grows from the spore - a pregrowth
D) there are no roots
D) sporangia are located on the underside of the leaf
E) have rhizomes

THE DEPARTMENT
1) Mossy
2) Ferns

In the table below, there is a relationship between the positions of the first and second columns.

What concept should be entered in place of the gap in this table?
1) swimming beetle
2) grape snail
3) toothless
4) triton

Establish the sequence of the ratio of systematic categories in plants, starting with the smallest. Write down the corresponding sequence of numbers in your answer.

1) genus Nightshade
2) plant kingdom
3) class Dipartite
4) Solanaceae family
5) Department of Angiosperms

In connection with the release of the first plants on land, they had
1) vegetative organs
2) seeds
3) disputes
4) gametes

Which of the following animals develops with transformation? Choose three correct answers from six and write down the numbers under which they are indicated in the table.
1) crested newt
2) lake frog
3) common toad
4) gigantic kangaroo
5) steppe turtle
6) Nile crocodile

Using the table "Some characteristics of the leaf blades of flowering plants", answer the following questions.
Table. Some characteristics of leaf blades of flowering plants

View	Area sheet surface, cm 2	Number of stomata
View	Area sheet surface, cm 2	Upper side of the sheet, 1 cm 2	The underside of the sheet, 1 cm 2
Cabbage	–	14 100	22 600
Corn	600– 1350	5200	6800
Sunflower	38	175	325
Wheat	13– 15	3300	1400
Beans	49	4000	28 100
Apple tree	18	0	29 400
Potato	–	5100	16 100
oats	12– 15	2500	2300

Note. (–) indicates no data.
1) Which of the following plants is characterized by the smallest leaf blade? Give two examples.
2) What features of the arrangement of stomata on a leaf are typical for dicotyledonous plants presented in the table?
3) What role do stomata play in plant cooling?

The ability of organisms to respond to changes in their environment is called
1) irritability
2) adaptation
3) regeneration
4) homeostasis

The trunk of a tree grows in thickness due to cell division
1) wood
2) cambium
3) bark
4) bast

Which of the proposed descriptions most accurately reflects this dependence? Insect growth throughout development occurs

3) jumps, periods of rest are replaced by a sharp increase
4) unevenly, so in the first days there is a sharp increase, which then becomes smooth

Plant tissues are groups of cells united by a common structure, function and origin. They make up the organs of a plant. Select the characteristics corresponding to the integumentary tissue of a woody plant according to the following plan: tissue function; features of the cellular structure of the tissue; location in the root, stem, leaf.

A. Function of plant tissue
1) protects the plant organism from adverse external influences
2) provides the conduction of nutrients throughout the plant body
3) provides plant growth, gives rise to all plant tissues
4) provides photosynthesis and mineral nutrition of the plant
5) stores nutrients

B. Features of the cellular structure of tissue
1) tissue cells of two types: elongated sieve tubes with holes in the transverse septa and tube-vessels with destroyed transverse septa
2) the tissue consists of a layer of living cells that secrete a waxy substance or several layers of dead cells that surround all parts of the plant organ from the outside

B. Location of tissue in the root
1) forms a growth point at the root
2) is located in the holding area
3) is located in the root bark

D. Location of tissue in the stem of a tree
1) is represented by cambium and is located between the bast and wood
2) is located in the cork part of the tree stem
3) represented by bast and wood fibers
4) represented by vessels of wood and sieve tubes of bast
5) located in the core

E. Location of tissue in a sheet
1) is located in the veins of the leaf
2) located in the pulp of the leaf, represented by columnar and spongy layers
3) represented by the skin of the leaf
4) located at the base
5) fabric for a normal sheet is not typical

Answer: A B C D D

In the table below, there is a relationship between the positions of the first and second columns.

What concept should be entered in place of the gap in this table?
1) lungs
2) intestines
3) gills
4) heart

Which trait is unique to mammals?
1) developed live birth
2) show concern for offspring
3) internal fertilization occurs
4) cubs are fed with milk

Consider a graph that shows the natural decline in the number of trunks per 1 hectare of land in the reserve. What is the main reason for the decline in the number of plants in a spruce forest?

1) interspecific struggle for existence
2) intraspecific struggle for existence
3) active human activity

Establish a sequence of complication of the organization of animals in the process of historical development of the organic world on Earth. Write down the corresponding sequence of numbers in your answer.

1) isolation of the brain
2) the formation of the internal skeleton
3) the appearance of warm-bloodedness
4) the appearance of two layers of body cells
5) development of the intestine with mouth and anus

The figure shows the flag shape of a pine growing on the seashore. What caused the development of such an unusual plant crown?

It is known that the common mole is a soil mammal that feeds on animal food. Using this information, select three statements from the list below that relate to the description of these features of this animal. Write in the table the numbers corresponding to the selected answers.
1) The body length of the animal is 18–26.5 cm, and the weight is 170–319 g.
2) Adult animals are quarrelsome, attack relatives who have fallen on their site and can bite them to death.
3) The offspring of moles are born blind, naked and helpless. At this time, the female feeds him with milk.
4) The nesting chamber is located at a depth of 1.5–2 meters.
5) Along the river valleys, the mole penetrates north to the middle taiga, and south to the typical steppes.
6) The mole feeds on earthworms, eats slugs, insects and their larvae in smaller quantities.

Which part of the stem carries water and minerals?
1) wood
2) cambium
3) bark
4) core

Which of the following molluscs is harmful to crop production?
1) naked slug
2) octopus
3) oyster
4) barley

1) mosses
2) green algae
3) brown algae
4) lichens

What organ of the bean seed performs the function of leaves during germination?
1) germinal root
2) endosperm
3) germinal stalk
4) cotyledons

What plants have underground shoots? Choose three correct answers from six and write down the numbers under which they are indicated in the table.
1) potatoes
2) strawberry
3) lily of the valley
4) plantain
5) bow
6) raspberries

The scientist has grown many gray and black moth butterflies in the laboratory. He released them in two areas: rural and urban. Gray butterflies were visible against the background of black tree trunks, and black butterflies were visible against the background of light trunks. Then the scientist himself caught butterflies. In addition, the scientist observed what color butterflies were most eaten by birds in different areas. The data of the experiment are presented in the table "The results of the experiment on the survival of butterflies of different colors." Using the table, answer the following questions.
Table. The results of the experiment on the survival of butterflies of different colors

terrain	Butterflies released and caught	Number of gray butterflies	Number of black butterflies
Uncontaminated (rural)	Released	469	473
	Caught by a scientist	30	120
	eaten by birds	26	335
polluted (urban)	Released	137	447
	Caught by a scientist	51	53
	eaten by birds	62	95

1) How many gray butterflies did the scientist release in the countryside, and how many in the city?
2) What butterflies were eaten more by birds in rural areas?
3) The reliability of which hypothesis did the scientist try to check by observing the capture of butterflies by birds?

Insert in the text "Arthropods" the missing terms from the proposed list, using digital designations for this. Write down the numbers of the selected answers in the text, and then enter the resulting sequence of numbers (in the text) into the table below.
arthropods
Arthropods are animals with __________ (A) bodies that have dense integuments from __________ (B) and jointed limbs on the outside. Unlike annelid worms, the body of most arthropods is subdivided into sections: the head, chest, or cephalothorax, and __________ (B). These include, for example, crayfish, __________ (G), spiders, flies, beetles. The phylum Arthropoda is the largest in terms of the number of animal species.

LIST OF TERMS:
1) ray symmetry
2) tail
3) shrimp
4) bilateral symmetry
5) gastropod
6) abdomen
7) chitin
8) fiber

In the table below, there is a relationship between the positions of the first and second columns.

What concept should be entered in place of the gap in this table?
1) jellyfish cornerot
2) lake frog
3) grape snail
4) malarial mosquito

What sign indicates the relationship of Archeopteryx with modern birds?
1) fingers with claws on the forelimbs
2) tarsus in the hind limbs
3) small teeth in the jaws
4) developed caudal spine

The development of new shoots in poplars after filing the top is due to the kidneys
1) apical
2) renewal
3) generative
4) sleeping

The absorption of food through the entire surface of the body occurs in
1) human roundworm
2) white planaria
3) bull tapeworm
4) liver fluke

The water needed for photosynthesis enters the leaves through
1) vacuoles
2) bast fibers
3) sieve tubes
4) vessels

In the table below, there is a relationship between the positions of the first and second columns.

What concept should be entered in place of the gap in this table?
1) lungs
2) heart
3) gills
4) skin

CHARACTERISTIC
A) movement is carried out with the help of fins
B) among the representatives of the class, the following ecological groups are distinguished: freshwater, anadromous, brackish, marine
C) have mastered the ground-air habitat
D) in most representatives, the skin is covered with scales
D) the skin of the representatives of the class is naked and covered with mucus
E) the heart has three chambers

ANIMAL CLASS
1) Bony fish
2) Amphibians

The main function of the root is
1) storage of nutrients
2) soil nutrition of plants
3) absorption of organic matter from the soil
4) oxidation of organic substances

Ch. Darwin attributed to the guiding driving force of evolution
1) hereditary variability
2) intraspecific struggle
3) interspecific struggle
4) natural selection

What role do the eyelids play in the life of terrestrial vertebrates?
1) provide three-dimensional vision
2) increase visual acuity
3) promote eye moisturizing
4) protect the eyes from changes in atmospheric pressure

1) the number of light butterflies will increase
2) the number of dark butterflies will increase
3) the number of light and dark butterflies will remain unchanged
4) dark butterflies will disappear completely

When using the depicted object in the evidence base for evolution, the scientist should use knowledge from the field

1) paleontology
2) physiology
3) biogeography
4) cytology

The appearance of what signs serves as a narrow adaptation of organisms to certain environmental conditions? Choose three correct answers from six and write down the numbers under which they are indicated in the table.
1) fetus in angiosperms
2) wings on maple fruits
3) burrowing limbs in a mole
4) spine in fish
5) four-chambered heart in mammals
6) masking coloration in a grasshopper

What sequence of stages of individual development is typical for the animal shown in the figure?
1) an egg is an adult insect
2) egg - larva - adult insect
3) egg - larva - pupa - adult insect
4) egg - pupa - larva - adult insect

The supply of oxygen to the body of the hydra occurs through
1) the entire surface of the body
2) breathing holes
3) gill slits
4) tentacle cells

The fruit of the solanaceous potato and tomato plants is called
1) tuber
2) root cone
3) root crop
4) berry

The main merit of Charles Darwin before science is
1) scientific explanation of the origin of life
2) creating a reflex theory
3) improvement of selection methods
4) explaining the reasons for the fitness of organisms

1) the occurrence of photosynthesis
2) development of seeds in cones
3) the occurrence of double fertilization
4) the emergence of heterotrophic organisms
5) the participation of oxygen in metabolic processes in cells

Using the table "Survival of starling chicks depending on the number of eggs in the clutch", answer the following questions.
Table. Survival of starling chicks depending on the number of eggs in the clutch

Number of eggs in clutch	Percentage of surviving chicks (in %)
1	100
2	95
3	90
4	83
5	80
6	53
7	40
8	35
9	32

1) What is the percentage of surviving chicks from a clutch that had 6 eggs?
2) What is the relationship between the number of eggs in a clutch and the proportion of surviving chicks?
3) From the data in the table it can be seen that the minimum proportion of surviving chicks can be up to 1/3. What are the three reasons for such a large proportion of dead chicks according to Charles Darwin?

What is characteristic of saprotrophic bacteria?
1) exist by feeding on the tissues of living organisms

3) use organic substances of the secretions of living organisms
Saprotrophic bacteria use not only organic substances secreted by other organisms, but also decompose animal corpses and plant remains.

What layer of a cross section of a woody stem is not visible to the naked eye?
1) bark
2) cambium
3) wood
4) core

Which animal first developed a thorax in evolution?
1) Amphibians
2) Reptiles
3) Birds
4) Mammals

What role does the mucus produced by the skin glands have in the life of amphibians? Choose three correct answers from six and write down the numbers under which they are indicated in the table.
1) dissolves oxygen
2) increases the surface of the skin
3) disinfects the skin
4) Protects from natural enemies
5) increases the speed of blood movement
6) promotes movement in the ground-air environment

Table. fish breeding

fish species	Number of eggs	Average diameter of eggs		in different reservoirs
Common pike	30 thousand	2.5–3 mm	34 years	5 years
norwegian herring	200 thousand	1.3 mm	27 years	8 years
Baltic cod	10 million	1 mm	5–9 years old	3 years
Carp	1.5 million	1 mm	5–6 years	8 years
Stickleback three-spined	100– 1000	1.8mm	1 year	2 years
common mackerel	450 thousand	1.1 mm	24 years	3 years

1) Which species of fish have the smallest diameter of eggs?
2) What pattern is observed between the fecundity of a species and the size of its eggs?
3) Which of the fish presented in the table has developed care for offspring? Prove your answer with the data in the table.

Which of the following fertilizers are classified as mineral fertilizers? Choose three correct answers from six and write down the numbers under which they are indicated in the table.
1) litter
2) superphosphate
3) ash
4) manure
5) peat
6) potassium sulfate

A progressive sign of flatworms in relation to coelenterates is
1) multicellular structure
2) three-layer body structure
3) ray symmetry of the body
4) free-living lifestyle

The supply of nutrients in a grain of wheat is in
1) germ
2) endosperm
3) seed coat
4) membranous pericarp

1) the appearance of the cortex in the cerebral hemispheres
2) formation of a chitinous cover
3) the emergence of ray symmetry of the body
4) development of the intestine with the mouth and anus
5) the appearance of jaws in the skull

Why, when picking mushrooms, the mushroom picker should not dig the soil around the fruiting body?
1) the mycelium of the fungus is destroyed
2) the root system of adjacent trees is damaged
3) soil fertility is disturbed
4) there is a massive death of soil insects

Preservation in nature of animals and plants with traits that are useful to them occurs in the process
1) variability
2) isolation
3) struggle for existence
4) natural selection

Consider a graph that shows the natural fluctuation over 90 years in the abundance of hares and lynxes. What is the main reason for the regular change in the number of lynxes?

1) change in the number of hares
2) infectious diseases
3) active human activity to shoot them
4) struggle with adverse environmental conditions

Establish a correspondence between the characteristic and the class of animals to which it corresponds: for each element of the first column, select the corresponding element from the second column.

CHARACTERISTIC
A) the circulatory system is represented by one circle of blood circulation
B) the heart is filled only with venous blood
C) the transformation of venous blood into arterial blood occurs in the gills
D) the circulatory system is represented by two circles of blood circulation
D) the heart contains both venous and arterial blood
E) the transformation of venous blood into arterial blood occurs in the lungs and skin

ANIMAL CLASS
1) Bony fish
2) Amphibians

The mycelium that entangles the roots of a plant is called
1) mycorrhiza
2) lichen
3) moldy
4) scion

1) head
2) abdomen
3) cephalothorax
4) chest

Which of the following refers to the results of evolution?
1) natural selection
2) struggle for existence
3) hereditary variability
4) adaptation of organisms to the environment

Reefs are special communities of marine organisms that form from
1) jellyfish
2) fish
3) corals
4) shellfish

Why is yeast used in bread making?
1) release oxygen
2) emit carbon dioxide
3) store energy
4) release energy

The higher spore plants are
1) common pine
2) kelp
3) white mushroom
4) bracken fern

The excretory system of the animal shown in the figure is shown

1) green glands
2) malpighian vessels
3) liver
4) paired kidneys

What animal has a stomach, the structure of which is shown in the figure?

1) dog
2) pig
3) cow
4) horse

Which plant cells transport organic matter from leaves?
1) vessels
2) sieve tubes
3) cells of the skin of the leaf
4) mechanical fibers

The germ of the bean seed, during germination, receives nutrients from
1) pericarp
2) soil
3) cotyledons
4) endosperm

What is the function of the skin cells of a leaf?
1) absorb water vapor from the atmosphere
2) protect the sheet from drying out
3) store water and organic matter
4) give the sheet strength and elasticity

Using the table "The number of stomata in some plants", answer the following questions.
Table. The number of stomata in some plants

1) How are the stomata located in most of the plants presented in the table?
2) Why is the number of stomata different in many plants? Give one explanation.
3) How does the number of stomata depend on the humidity of the plant habitat?

Potato tubers are formed on
1) lateral roots
2) adventitious roots
3) modified underground shoots - stolons
4) modified underground shoots - rhizomes

The sieve tubes of the woody stem are part of
1) wood
2) cambium
3) bark bast
4) cork bark

The merit of C. Darwin lies in the fact that he
1) recognized the variability of species
2) developed a modern classification of animals and plants
3) proved that acquired traits are inherited
4) created the doctrine of natural selection

With the help of what organelles are protozoa freed from harmful metabolic products dissolved in water?
1) digestive vacuoles
2) contractile vacuoles
3) protrusions of the cytoplasm - pseudopods
4) oral cavity and cell pharynx

Mushrooms are classified as a separate kingdom because they
1) reproduce by spores
2) immobile heterotrophs
3) are not capable of photosynthesis
4) consist of cells that do not have nuclei

Which ecological group of birds feeds mainly on insects?
1) birds of the forest
2) birds of the steppes and deserts
3) open air birds
4) birds of marshes, fresh waters and coasts

What plants have bright single flowers? Choose three correct answers from six and write down the numbers under which they are indicated in the table.
1) field poppy
2) red clover
3) May lily of the valley
4) common narcissus
5) common dandelion
6) yellow tulip

By what process is it possible to observe the diversity of the depicted breeds of domestic chickens?

2) interspecific struggle
3) natural selection
4) artificial selection

Goiter as a modification of part of the esophagus is developed in birds that feed on
1) insects
2) plant seeds
3) juicy fruits of plants
4) small rodents

Move in a reactive way
1) marine single polyps
2) free-living flatworms
3) marine annelids
4) cephalopods

The driving forces of evolution are
1) adaptation of organisms to the environment
2) variety of organisms
3) struggle for existence
4) the formation of new species

Examine the plot of insect growth versus time (the x-axis is time (days) and the y-axis is insect length (in cm)).

Which of the proposed descriptions most accurately reflects the process of insect growth in the interval from 26 to 32 days? During this period, the insect grows
1) smoothly, without visible jumps
2) very sharp all the time
3) jumps, the period of rest is replaced by a sharp increase
4) at first abruptly, and then the growth stops completely

LIST OF TERMS:
1) sunflower
2) unicellular
3) cyst
4) plasmodium
5) fluke
6) multicellular
7) mosquito
8) zygote

1) the appearance of the digestive system
2) the emergence of the circulatory system
3) the appearance of trachea and spiracles
4) development of unicellular heterotrophic organisms
5) the appearance in the body of two layers of cells

What part of the body of crayfish is indicated by the letter A in the figure?

1) tail
2) abdomen
3) cephalothorax
4) chest

What is the structure of the mycelium penicilla?
1) branching threads of the mycelium are separated by partitions into separate cells, plastids are absent
2) branching threads of the mycelium are separated by partitions into separate cells, there are plastids
3) one strongly expanded cell with many nuclei, there are plastids
4) one strongly expanded cell with many nuclei, plastids are absent

SIGN
A) some representatives in development have a pupal stage
B) the vast majority are predators
C) the body consists of the head, thorax and abdomen
D) can only eat liquid food
D) the number of walking legs - 4 pairs
E) simple and compound eyes can be located on the head

ANIMAL CLASS
1) Insects
2) Arachnids

What process makes it possible to observe the diversity of the depicted breeds of pigeons?

1) the fight against adverse environmental conditions
2) natural selection
3) artificial selection
4) intraspecific control

The bulb is a modified shoot, this proves the presence of
1) main root
2) buds-eyes
3) underground stolons
4) flat stem - bottom

Which factor does not affect seed germination?
1) water
2) warm
3) soil
4) air It would be better to formulate this question as : Which factor is not required for seed germination?

Using the table "Some parameters of animals and humans", answer the following questions.
table Some parameters of animals and humans

1) Which of the ungulates listed in the table has the maximum running speed?
2) Does the running speed of an animal depend on body weight?
3) Between which of the given organisms there are relations "predator - prey"?

Insert the missing terms from the proposed list into the text "Annelled worms" using digital designations for this. Write down the numbers of the selected answers in the text, and then enter the resulting sequence of numbers (in the text) into the table below.
RINGED WORMS
Annelids are animals that have a long __________ (A) body. They are like flatworms and roundworms - __________ (B) animals with __________ (C) body symmetry. Annelids have __________ (D) and more complex nervous system and sensory organs than other worms. Annelids live in the seas, fresh waters, soil.

LIST OF TERMS:
1) two-layer
2) jointed
3) circulatory system
4) double sided
5) non-segmented
6) three-layer
7) radial
8) respiratory system

What is the function of the cap of the fruiting body of the boletus?
1) serves to attract animals and humans
2) captures solar energy, providing photosynthesis
3) is a place of spore formation
4) provides air supply

In angiosperms, unlike gymnosperms,
1) an embryo is formed in the seed
2) the body is made up of organs and tissues
3) double fertilization is carried out
4) fertilization occurs without the participation of water

What structural feature is similar in modern reptiles and birds?
1) bones filled with air
2) dry skin, devoid of glands
3) tail section in the spine
4) small teeth in the jaws

The organ of a flowering plant designed to protect its seeds is
1) peel
2) bump
3) fruit
4) ovule

The main root develops from
1) lateral roots
2) germinal root
3) adventitious root
4) dormant kidneys

Establish a sequence of complication of the organization of organisms in the process of historical development of the organic world on Earth. Write down the corresponding sequence of numbers in your answer.

1) the appearance of rhizoids
2) the formation of seeds in fruits
3) the occurrence of photosynthesis
4) the formation of seeds in cones

1) fitness of organisms
2) natural selection
3) struggle for existence
4) heredity and variability

With the help of what organs does a free-living white planaria worm get rid of harmful metabolic products dissolved in water?
1) mouth and throat
2) skin and muscles
3) excretory tubules
4) intestines and anus

The formation of new species in nature occurs as a result of
1) regular seasonal changes in nature
2) age-related physiological changes in individuals
3) interactions of driving forces (factors) of evolution
4) human environmental activities

Establish a correspondence between the plant and the method of distribution of its fruits and seeds: for each element of the first column, select the corresponding element from the second column.

PLANT
A) birch
B) apple tree
B) a rose (in the original OGE test there was a mountain ash, maybe a rose = rosehip here)
D) poplar
D) sunflower
E) burdock

METHOD OF DISTRIBUTION OF FRUITS AND SEEDS
1) wind
2) animals

The figure shows a representative of one of the classes of angiosperms. Members of this class usually have

1) one cotyledon per seed
2) six tepals perianth
3) net venation of leaves
4) fibrous root system

What adaptations do plants have to make better use of light?
1) the presence of a wax coating on the skin of the leaf
2) pubescence of leaf blades
3) the presence of a large number of stomata on the upper skin of the leaf
4) arrangement of smaller leaves between larger leaves

What group of animals arose in the process of evolution later than the others?
1) arthropods
2) intestinal
3) roundworms
4) flatworms

Representatives of the chordate type, unlike other animals, have
1) three-layer structure
2) internal skeleton
3) body cavity
4) circulatory system

Examine the plot of insect growth versus time (the x-axis is time (days) and the y-axis is insect length (in cm)).

Which of the proposed descriptions most accurately reflects the process of insect growth in the interval from 6 to 14 days? During this period, the insect
1) does not grow
2) grows very fast over time
3) grows spasmodically, periods of rest are replaced by a sharp increase
4) at first it grows sharply, and then its growth stops

Examine the plot of insect growth versus time (the x-axis is time (days) and the y-axis is insect length (in cm)).

Which of the proposed descriptions most accurately reflects the process of insect growth in the interval from 32 to 40 days? Insect growth during this period
1) occurs smoothly, without visible jumps
2) slow down all the time
3) occurs abruptly, the rest period is replaced by a sharp increase
4) missing

Establish the sequence of appearance on Earth of the main groups of plants in the process of evolution. Write down the corresponding sequence of numbers in your answer.

1) psilophytes
2) unicellular green algae
3) multicellular green algae
4) ferns
5) gymnosperms

By what process can one observe the diversity of the depicted varieties of cabbage?

1) the fight against adverse environmental conditions
2) natural selection
3) artificial selection
4) intraspecific competition

In the table below, there is a relationship between the positions of the first and second columns.

What concept should be entered in place of the gap in this table?
1) hydra
2) toad
3) bee
4) toothless

Reindeer moss in its structure is attributed to
1) mushrooms
2) lichens
3) mossy
4) herbaceous plants

Root growth in length occurs due to cell division
1) root hairs
2) educational tissue
3) holding areas
4) root cap

What life form is most often found in monocotyledonous plants?
1) herbs
2) shrubs
3) shrubs
4) trees

In the table below, there is a relationship between the positions of the first and second columns.

What concept should be entered in place of the gap in this table?
1) leaflet
2) embryo
3) basket
4) seed

The digestive system is absent
1) human roundworm
2) white planaria
3) bull tapeworm
4) liver fluke

1) bull tapeworm
2) echinococcus
3) roundworm
4) liver fluke

In green mosses, unlike algae,
1) cells have large and small nuclei
2) fertilization occurs in the presence of water
3) the thallus is divided into tissues and organs
4) sexual and asexual reproduction is carried out

Rhizome - a modified shoot, this proves the presence on the rhizome
1) main root
2) membranous scales
3) flat stem - bottom
4) mechanical fibers

A representative of which department of the plant kingdom is shown in the figure?

On what basis are plants grouped into one family?
1) the same area
2) similar structure of flower and fruit
3) the same number of cotyledons in the seed
4) the presence of sexual and asexual methods of reproduction

With the death of marine shell rhizomes, the formation of
1) peat
2) granite
3) limestone
4) hard coal

Establish a correspondence between the trait and the class of animals for which it is characteristic: for each element of the first column, select the corresponding element from the second column.

SIGN
A) eggs are large, with a large amount of yolk
B) the heart is three-chambered and has an incomplete septum
C) the skin contains sweat and sebaceous glands
D) the body temperature of the representatives is unstable
D) well-developed care for offspring
E) common in northern latitudes

CLASS
1) Reptiles
2) Mammals

The appearance of what signs is an example of the narrow adaptation of organisms to certain environmental conditions? Choose three correct answers from six and write down the numbers under which they are indicated in the table.
1) chords in non-cranial
2) flowers in angiosperms
3) sharp fangs in wolves
4) mammary glands in mammals
5) pollination of wild rose flowers by insects
6) long main root of camel thorn
Answer:

Mammals descended from ancient
1) dinosaurs
2) animal-toothed lizards
3) lobe-finned fish
4) tailed amphibians

What number in the figure indicates the placenta?

1) 1
2) 2
3) 3
4) 4

Examine the plot of insect growth versus time (the x-axis is time (days) and the y-axis is insect length (in cm)).

In what time interval is the maximum increase in the size of the insect's body observed?
1) 6-7th day
2) 14–15th day
3) 33–34th day
4) 40–41 day

Using the table "Reproduction of fish", answer the following questions.
table fish breeding

fish species	Number of eggs	Average diameter of eggs	Average age of sexual maturity	Average age of fish caught in different reservoirs
Common pike	30 thousand	2.5–3 mm	34 years	5 years
norwegian herring	200 thousand	1.3 mm	27 years	8 years
Baltic cod	10 million	1 mm	5–9 years old	3 years
Carp	1.5 million	1 mm	5–6 years	8 years
Stickleback three-spined	100– 1000	1.8mm	1 year	2 years

1) What is the range of average sizes of fish eggs presented in the table?
2) What kind of fish populations can be undermined by intensive fishing? Explain the answer.
3) Why, according to the theory of Charles Darwin, with such fecundity, the number of fish remains relatively constant?

What analyzer is used to orientate bats in space?
1) visual
2) olfactory
3) tactile
4) auditory

In the table below, there is a relationship between the positions of the first and second columns.

What concept should be entered in place of the gap in this table?
1) receptacle
2) pestle
3) stamen
4) whisk

Establish the sequence of the systematic position of the white hare species, starting with the smallest group. Write down the corresponding sequence of numbers in your answer.

1) detachment Lagomorphs
2) class Mammals
3) Hare family
4) genus Hares
5) type Chordates

Establish a correspondence between the plant and the type of its underground shoot: for each element of the first column, select the corresponding element from the second column.

PLANT
A) wheatgrass
B) lily
B) lily of the valley
D) daffodil
D) bought a pharmacy
E) common garlic

TYPE OF UNDERGROUND Escape
1) rhizome
2) bulb

K. Linnaeus, in his system of living nature, erroneously attributed the depicted animal to fish, but it should be correctly attributed to the class

1) Mammals
2) Amphibians
3) Cephalopods
4) Reptiles

The plant shown in the figure reproduces asexually by means of

1) seeds
2) gamete
3) dispute
4) hyphae

Which of the following appeared in the process of evolution in flatworms in comparison with coelenterates?
1) intestinal cavity
2) endoderm
3) circulatory system
4) third germ layer

Which ecological group does the bird shown in the picture belong to?

1) birds of open spaces
2) diurnal predators
3) nocturnal predators
4) insectivorous forest birds

The movement of dissolved minerals from the roots to the leaves in the plant body occurs through
1) vessels
2) sieve tubes
3) cambium cells
4) mechanical fibers

Insects breathe with
1) gill
2) trachea
3) lungs
4) lung bags

A flower that has both stamens and pistils is called
1) dioecious
2) bisexual
3) monoecious
4) dioecious

What are the characteristics of putrefactive bacteria?
1) use ready-made organic substances of living organisms
2) synthesize organic substances from inorganic ones using the energy of the sun
3) use organic matter of dead organisms
4) synthesize organic substances from inorganic ones, using the energy of chemical reactions

By what process can the variety of dog breeds depicted be observed?

1) the fight against adverse environmental conditions
2) natural selection
3) artificial selection
4) intraspecific control

Angiosperms include plants
1) Mossy
2) Ferns
3) Gymnosperms
4) Dicotyledons

Which trait is characteristic of plants of the class Dicotyledonous?
1) the number of petals in flowers is a multiple of 3
2) tap root system
3) arc venation of leaves
4) parallel venation of leaves

What does a freshwater hydra polyp eat?
1) bacteria
2) small crustaceans
3) unicellular animals
4) unicellular algae

1) Mossy
2) Ferns
3) Gymnosperms
4) Lycopsoid

What is characteristic of a bacterial cell?
1) the ring chromosome is located in the cytoplasm
2) the nucleus is separated from the cytoplasm by two membranes
3) transport of substances through the ER of the cell
4) oxidation and storage of energy in mitochondria

The figure shows the head of a frog. Which organ is labeled A in the figure?

1) eye with eyelid
2) eardrum
3) organ of touch
4) lateral line

A representative of which department of the plant kingdom is shown in the figure?

What does the infusoria-shoe eat?
1) bacteria
2) small crustaceans
3) insect larvae
4) unicellular animals

1) the appearance of the external skeleton
2) the appearance of a five-fingered limb
3) the emergence of the circulatory system
4) the development of cubs in the uterus of the female
5) the supply of oxygen through the entire surface of the body

Establish a sequence of subordination of systematic categories, starting with the smallest. Write down the corresponding sequence of numbers in your answer.

1) cruciferous family
2) Department of Angiosperms
3) genus Radish
4) class Dicotyledonous
5) plant kingdom

Representative of what type of animal kingdom is shown in the picture?

1) digestive
2) nervous
3) respiratory
4) muscular

What are the results of evolution?
1) isolation of organisms
2) the struggle for existence between organisms
3) heredity and variability in organisms
4) the formation of a new species

A sign of the amphibian class is
1) chitinous cover
2) bare skin
3) live birth
4) paired limbs

Among vertebrate animals, care for offspring is most strongly developed in
1) freshwater fish
2) amphibians
3) reptiles
4) mammals

Bright odorous flowers in angiosperms appeared in the process of evolution as an adaptation to
1) storage of nutrients
2) distribution of seeds and fruits
3) terrestrial habitation
4) attract insects

The lower plants are
1) mosses
2) algae
3) horsetails
4) ferns

What is the function of leaf stomata?
1) release water vapor into the atmosphere
2) absorb quanta of sunlight
3) prevent dust particles from entering the sheet
4) prevent harmful chemicals from entering the sheet

Infusoria slipper, unlike hydra,
1) uses oxygen for breathing
2) consists of one cell
3) has chloroplasts
4) feeds on ready-made organic substances

Insert in the text "Bacteria" the missing terms from the proposed list, using digital symbols for this. Write down the numbers of the selected answers in the text, and then enter the resulting sequence of numbers (in the text) into the table below.
BACTERIA
Among bacteria there is a group of organisms living in an oxygen-free environment, i.e. being __________ (A). Under unfavorable conditions, they can form __________ (B). Many bacteria have __________ (B) with which they move. Hereditary information in these microorganisms is stored in __________ (D).

LIST OF TERMS:
1) nucleus chromosome
2) aerobe
3) ring chromosome
4) anaerobe
5) pseudopod
6) dispute
7) flagellum
8) cyst

1) the emergence of seeds
2) the appearance of a flower
3) the occurrence of photosynthesis
4) the appearance of plant tissues
5) formation of root systems

What physiological process in unicellular animals is associated with the absorption of gases by the cell?
1) food
2) selection
3) reproduction
4) breathing

The cerebral cortex, which has furrows and convolutions, first appeared in
1) amphibians
2) reptiles
3) birds
4) mammals

The figure shows a representative of the department

1) Bryophytes
2) Ferns
3) Green algae
4) Angiosperms

Establish a correspondence between the plant and the method of its pollination: for each element of the first column, select the corresponding element from the second column.

PLANT
A) rosehip
B) cherry
B) sunflower
D) rye
D) alder

POLLINATION METHOD
1) insects
2) wind

Establish the sequence of subordination of systematic categories in plants, starting with the largest. Write down the corresponding sequence of numbers in your answer.

1) family of water lilies
2) Department of Angiosperms
3) view yellow capsule
4) genus Kubyshka
5) class Dicotyledonous
6) plant kingdom

How does sphagnum peat moss eat?
1) absorbs water and mineral salts by rhizoids
2) absorbs minerals from the soil by roots
3) forms organic substances from water and carbon dioxide
4) absorbs organic matter from water with the entire surface of its body

***********************************************************************

My biology tutor's answers to these 200 questions of the FIPI OGE Open Task Bank of the section "System, Diversity and Evolution of Wildlife" and to all the other 1724 questions of this section you can

LAB #5

WATER EXCHANGE. LEAF AS A TRANSPIRATION ORGAN

Objective: study of the most important functional features of a plant leaf as an organ of transpiration: the structure and number of stomata on a leaf blade, the mechanism of opening and closing of stomata, the influence of various substances on the movement of stomata.

TRANSPIRATION

The biological significance of transpiration is, firstly, to ensure the constancy of the internal temperature of the leaf. This is achieved by the absorption of heat by water during its evaporation by leaves. The energy required to transfer a molecule from a liquid phase to a gaseous state without changing temperature is called heat of evaporation. The expenditure of heat for the evaporation of water is a means of regulating the temperature of the leaves and preventing the plants from overheating.

Secondly, transpiration, being the upper end engine, ensures the supply of water and mineral nutrients to the roots. The presence of a positive correlation between the intensity of transpiration and the flow of water and ions was established. If the leaves are removed from the plant, then the absorption of water by the roots stops. The suction action of transpiring leaves can be verified by placing a cut branch in a pipette filled with water and immersed in a cup of mercury. After some time, you can observe the rise of mercury in the pipette, which will indicate a significant suction force of the leaves.

Thus, the rate of water entry into the roots is determined by the intensity of transpiration.

Thirdly, transpiration prevents the occurrence of excessive turgor pressure, which could lead to the destruction of plant cells.

Fourthly, the process of transpiration is closely related to plant photosynthesis, which was noted by the works of K. A. Timiryazev. The assimilation of CO 2 by the leaves of plants occurs through the stomata, and it depends on the degree of saturation of the leaf tissue with water. The process of assimilation of water and carbon dioxide is a single and inseparable whole.

Under the intensity of transpiration is understood the amount of evaporated water per unit of time per unit of leaf area. Usually this indicator has a dimension - mg / dm 2 hour. The amount of water evaporated by plants is quite large, and often exceeds the amount of precipitation during the growing season. This excess is compensated by autumn-winter precipitation. So, for example, one sunflower or corn plant spends 200-250 liters of water over the summer. Wheat plants on an area of 1 ha evaporate about 2 million liters of water during the summer, corn - more than 3 million, and cabbage - up to 8 million liters. In the process of formation of one kilogram of plant mass, 300 liters are consumed. Water.

Stomatal transpiration is regulated by the degree of stomatal openness. Their structure and distribution depends on the species and ecological characteristics of plants. Stomata are found on all terrestrial parts of plants, including reproductive organs and even filaments. The most characteristic stomata for leaves. More often they are located on the underside of the leaves (in mesophytic plants). However, in xerophytes, they are also found on the upper side of the leaf.

The average number of stomata per 1 mm 2 of area ranges from 100 to 300. The size of the stomata does not exceed 20 microns in length and 8-15 microns in width. The total area of open stomata is 1% of the leaf surface.

It has been established that small apical leaves have a greater number of stomata than large lower ones. The frequency of stomata (their number per unit area) increases with the transition from the base of the leaf to its top and from the bottom of the plant to the top. Plants in arid habitats have more of them, but they are smaller in size.

In most mesophytic plants, the stomata are located at the same level as the epidermal cells, while in xerophytic forms, the stomata are located below the level of the epidermis and are called submerged. In hygrophytes, guard cells are sometimes located above the epidermis. Such stomata are called raised.

One or another type of stomata structure is characteristic of certain groups of plants, although within the same family, different types of stomata can sometimes be found. Despite the large area occupied by stomata, the diffusion of water vapor through them is 50-60% of evaporation from the free surface. It has been established that the rate of diffusion through small holes is proportional to their perimeter, and not to the area. Therefore, partial closure of the guard cells has little effect on their perimeter, and the level of water vapor diffusion through the stomata does not drop very sharply.

Experience 1. Observation of the movement of stomata under a microscope.

Purpose of experience: to determine the dependence of the work of stomata on osmotically active substances.

Materials and equipment: 5% glycerin solution, razor, dissecting needle, microscope, glass slides and coverslips.

Plants: leaves (Tradescantia, tulip, hydrangea or amaryllis, Kalanchoe).

Gas exchange between the intercellular spaces of the leaf and the external atmosphere is regulated by stomata. Each stomata consists of two guard cells, in which the walls adjoining the stomatal fissure are strongly thickened, while the outer parts of the membrane remain thin. The unequal thickness of the outer and inner walls leads to the fact that when the turgor changes, the guard cells are able to bend or straighten, opening or closing the stomatal gap.

Working process: sections of the epidermis of the leaf of the selected plant are made, which are placed in a 5% solution of glycerol and incubated for at least 1 hour. The sections are examined under a microscope, the degree of opening of the stomatal fissure is determined using an eyepiece micrometer. Do 10 measurements, find the average value and calculate the error of the mean. Then the sections are transferred from the glycerol solution into water and the measurements of the stomatal fissures are repeated under a microscope. The results are entered in table 1.

Table 1

The degree of opening of the stomatal gap in different environments

plant, organ	No. of sounding	Degree of stomatal opening
plant, organ	No. of sounding	Glycerol
plant leaf

The task: to draw a conclusion about the effect of glycerol and water on the opening and closing of stomata.

Experience 2. Determination of the state of stomata and intercellular spaces by the Molisch method

Purpose of experience: will determine the influence of external conditions on the state of stomata and the intensity of transpiration.

Materials and equipment: xylene (in a dropper), ethyl alcohol (in a dropper); benzene (in a dropper), pipettes.

Plant: fresh or withered leaves of plants, leaves of plants that were in the dark.

The intercellular spaces of the leaf are usually filled with air, due to which, when viewed in the light, the leaf appears dull. If you infiltrate, i.e. filling the intercellular spaces with some liquid, then the corresponding parts of the leaf become transparent.

Determination of the state of stomata by the method of infiltration is based on the ability of liquids that wet the cell membranes to penetrate by capillarity through open stomatal slits into the nearest intercellular spaces, displacing air from them, which is easily seen by the appearance of transparent spots on the leaf. Different liquids are able to penetrate into stomatal openings that are open to varying degrees: xylene easily penetrates through slightly open stomata, benzene through medium open stomata, and ethyl alcohol can only penetrate through wide open stomata.

This method, proposed by Molisch, is very simple and quite applicable to work in the field.

Working process. Apply small drops of benzene, xylene and ethyl alcohol separately to the lower surface of the sheet. Hold the sheet in a horizontal position until the drops completely disappear, which can either evaporate or penetrate the inside of the sheet, and examine the sheet in the light.

Examine leaves aged in various conditions (fresh and withered, illuminated and shaded, etc.). Each time examine 2-3 sheets.

1.7 Number of stomata and their distribution on the leaf

The number of stomata on the leaf surface ranges from several hundred to 1000 per 1 mm² of the leaf surface. Most herbaceous plants have stomata on both sides of the leaf. Many shade-tolerant plants only have stomata on the underside of the leaf. The majority of tree species (birch, oak, poplar, etc.) also differ in this feature. Despite the fact that stomata make up a very small part of the leaf area (the area of their openings in the open state is about 1%), the release of water vapor through open stomata occurs unhindered. According to Stefan's law, the diffusion of water vapor on surfaces is proportional to their diameter, not their area. In this regard, evaporation from a vessel with many holes is faster than from a vessel with one large hole. For this, however, one condition is necessary, namely, small holes must be located at a known distance from each other. The location of the stomata in the epidermis of the leaf corresponds exactly to this.

Evaporation from the edges of the holes is faster than from their middle. In the middle of the hole, the evaporating particles have a greater influence on each other, and the evaporation slows down. On this basis, the greater the ratio of the perimeter to the area of the hole, the more intense the diffusion of cleaners will go, since these ratios are greater, the smaller the diameter of the hole.

It follows from the foregoing that the total rate of diffusion through a finely perforated membrane will occur at almost the same rate as from a vessel without a membrane. The latter can be clearly seen from the diagram in Figure 4.

Figure 4. Scheme of water vapor evaporation from an open vessel (1) and through a finely perforated membrane (2).

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