The root can absorb water with solutes. Water uptake by the root
FUNCTIONS OF THE ROOT - ABSORPTION FROM THE SOIL OF WATER WITH MINERAL SUBSTANCES DISSOLVED IN IT (ROOT NUTRITION); - ANCHORING THE PLANT IN THE SOIL; - ACCUMULATION (storage) of NUTRIENTS; - PRIMARY SYNTHESIS OF SOME ORGANIC SUBSTANCES (chlorophyll (leukoplasts chloroplasts) is produced in the aerial roots of some tropical plants; it is dark, lack of light, increased f / s intensity); - VEGETATIVE REPRODUCTION IN ROOT PLANTS (RASPBERRY, PLUM, SEA BUCKTHORN)
How can you explain that the roots of some plants, for example, orchids, can turn green in the light? 1) Orchids live in dark rainforests. 2) To increase the intensity of the process of photosynthesis in the cells of the roots, chlorophyll is formed
ROOT ZONES. Mycorrhiza of the root hair - lateral growth of the cells of the skin of the root = suction zone. MYCORIZA (MUSHROOT) - SYMBIOSIS OF GRIBNITS AND ROOT. THE MUSHROOM FUNCTIONS OF ROOT HAIRS (WATER, MINERAL SALTS, VITAMINS) - INCREASING THE SUCTION SURFACE OF THE ROOTS - GIVING THE MUSHROOM A SOLUTION OF ORGANIC SUBSTANCES (MUSHROOMS - HETERO)
PERICYCLE - (outer layer of procambium) the outer zone of the central cylinder of the stem and root; consists of one (at the root) or several (in the stem) layers of cells. In young organs, the PERICYCLE is represented by the primary lateral meristem, the cells of which in the stem later lose their ability to divide and fully differentiate, turning into sclerenchyme fibers. At the root, PERICYCLE participates in the formation of cambium, phellogen, lateral roots and root suckers. Laying of lateral roots (a) in the pericycle of the main root: 1 - central cylinder of the main root, 2 - pericycle, 3 - endoderm, 4 - crustal parenchyma, 5 - rhizoderm.
A team of researchers led by University of Wisconsin botanist Simon Gilroy, using state-of-the-art equipment, has been able to video the growth of thin elongations of individual root cells known as root hairs. The roots of the plant are literally covered with millions of these elongated leathery outgrowths. Scientists have long understood that root hairs significantly increase the surface area of the plant's root system, which means they also increase the volume of soil from which the roots take water and minerals.
Root hair Path along the apoplast Transport of water and mineral salts Path along the symplast of the epidermis of the cortex Transport of water and mineral salts through the apoplast system (interconnected cell walls) and symplast (along the cytoplasm through pores in the cell wall) endodermis pericycle vessels
WATER GETS INTO THE ROOT HAIR CELL DUE TO THE PHENOMENON OF OSMOSIS (OSMOSIS - DIFFUSION OF WATER). WATER PENETS INTO THE ROOT HAIR, BECAUSE THE CONCENTRATION OF CELLULAR JUICE AT THE ROOT HAIR, AS A RULE, IS HIGHER THAN IN THE SOIL SOLUTION. THE CELL WALL PASSES WATER FREELY, BUT THE ADJACENT PLASMALEMMA (cell membrane), SURROUNDING THE CYTOPLASM, IS SEMI-PERMEABLE AND RETAINS DISSOLVED SUBSTANCES. A SINGLE-WAY CURRENT IS ESTABLISHED AT WHICH WATER CONTINUOUSLY ENTERS THE PLANT. CELLS LOCATED CLOSER TO THE ROOT CENTER, IN DIFFERENCE FROM PERIPHERAL CELLS, CONTAIN CONCENTRATED SOLUTIONS OF GLUCOSE AND OTHER ORGANIC SUBSTANCES. THEREFORE, OSMOTIC STRENGTH INCREASES ACCORDING TO THE REMOVAL FROM ROOT HAIR TO THE ROOT CENTER. WATER, THIS WAY, CONSTANTLY MOVES FROM CELL TO CELL, UNTIL ENDS AT THE END OF THE ENDS INTO THE VESSELS OF THE ROOT WOOD, AND THEN AND THE STEM.
ROOT ABSORPTION OF WATER AND MINERAL SUBSTANCES. The absorption of nutrients by the root takes place in an active and passive way. The active one is associated with metabolic processes, with the expenditure of energy, with the processes of respiration. The second, passive, is associated with the diffusion of substances. It does not depend on metabolic processes. Through root hairs, water with minerals enters through the passage cells into the vessels of the central cylinder. The place where the root passes into the stem, that is, the root vessels in the stem, is called the root collar. It is somewhat thickened. Hydrostatic pressure is formed due to the entry of water into the vessel from the parenchymal cells that surround them. This pressure is called root pressure. The ability of the root system to lift water up the stem is called the lower root mover. The upward current from the root to the aboveground part of the plant is explained by the presence of root pressure and the suction action of the leaves due to transpiration (evaporation of water by the leaves).
SATURATION OF CELLS WITH WATER - TURGOR The value of turgor pressure in all parts of the plant is the same. Turgor (from Latin turgor - swelling, filling) is a stressed state of the cell membrane, which occurs due to the hydrostatic pressure of the cell contents. Due to turgor, plant tissues have a certain elasticity. Osmotic pressure is the excess pressure from the solution side, which prevents the penetration of the solvent through the semipermeable membrane from a less concentrated solution to a more concentrated solution. Osmosis is the diffusion of water through a semipermeable membrane from an area of a lower concentration of a solute to an area with a higher concentration of it until they level off. The suction force is greater in the part where the osmotic pressure is greater: S = P-T, where S is the suction force, P is the osmotic pressure, T is the turgor pressure. Internal pressure on the plant cell wall always exceeds the pressure on it from the external environment.
MYCORIZA - SYMBIOSIS (MUTUALISM) OF GRIBNITS AND ROOT. GRIBNITSA - FUNCTION OF ROOT HAIRS - GIVES WATER TO THE WOOD AND MINERAL SALTS WOOD - A SOLUTION OF ORGANIC SUBSTANCES TO THE GRIBNITS (MUSHROOM - HETEROTROPH).
ROOT SYSTEM - ALL ROOTS OF ONE PLANT MAIN ROOT - DEVELOPS FROM GERMINAL ROOT (always 1), positive geotropism ADDITIONAL ROOTS - DEVELOP FROM THE ROOT (stem, leaf, flower)
Why does hilling potatoes increase their yield? 1) Hilling stimulates the formation of adventitious roots, which means that it increases the mass of the root system. 2) As a result, root nutrition is improved and the yield of potatoes increases. 3) Hilling stimulates the formation of tubers stolons
CORE ROOT SYSTEM WELL EXPRESSED THE MAIN ROOT OF THE ROOT: MAIN + LATERAL + SUPPLEXATE URINATE MAIN ROOT IS NOT EXPRESSED (NOT DEVELOPED AND DOESN'T DIFFER FROM THE LATERAL AND REPEATED, ANCIENT ROOT) fibrous
NITROGEN PROTEINS, ATP, NUCLEIC ACIDS LEGANES - "PLANT BEEF" On the roots of many legumes, small nodules develop, formed by overgrown tissue after the introduction of bacteria of the genus rhizobium into it. They are able to fix atmospheric nitrogen, converting it into compounds that are easily assimilated by plants.
HONEY MESKITA (FAMILY LEGUMES) ROOT OF SOME GORGEOUS PLANTS CAN GO TO GREAT DEPTH DEPENDING ON HABITATING CONDITIONS. FOR EXAMPLE, ALFALFA SICKLE OVER 2 M (WITH A GROUND PART HEIGHT OF 60 CM), BODYAK - MORE THAN 6 M (Above ground part 1 M), BEAN'S CAMEL BEAN UP TO 20 M (Above the ground part of 60 cm). THE RECORD DEPTH FIXED AT THE DESERT MESQUITO SHRUB (PROSOPIS JULIFLORA) - 53, 3 M.
BY SHAPE: CYLINDRICAL - the same diameter along the entire length (peony, poppy); KNOTED - uneven nodules in the form of knots (meadowsweet, ginger)
The root system is the collection of roots of one plant. Classification of root systems by origin: main root system - develops from the embryonic root. Represents the main root of the first order with lateral roots of the second and subsequent orders (in trees and shrubs and in annual and perennial herbaceous dicotyledons); system of adventitious roots - an embryonic tuber develops from a seed, and on it - adventitious roots (in orchids); mixed root system - during life the type of root system changes, the main root system is replaced by a system of adventitious roots (in monocots and dicots). Classification of root systems by shape: tap root - the main root is longer than the lateral ones; fibrous - the main and lateral roots are of the same length. Due to the tenacity of this root system, a sod cover is created, preventing soil erosion. The root of some plants can go to great depths, depending on the living conditions. For example, in crescent alfalfa over 2 m (with a height of the ground part of 60 cm), in a thistle - more than 6 m (aboveground part 1 m), in camel thorn up to 20 m (aboveground part 5060 cm). A record depth was recorded for the desert mesquite bush (Prosopis Juliflora) - 53.3 m.
ROOT STEM ROOT VARIATION OF THE MAIN ROOT ALWAYS ONE ROOT OF ROOT CELERY ROOT TOP - SHORT VARIOUS VARIED STEM (GREEN IN THE LIGHT) + DENSIFIED THICKNESS
ROOT - THICKNESS OF THE MAIN ROOT ASSOCIATED WITH DEPOSIT IN IT OF A STOCK OF NUTRIENTS (CARROT, BEET, REDIS, ETC.).
ROOT TUBERS OF THE SPECIES OF LATERAL OR SUPPLEMENTARY ROOTS ALWAYS A LOT OF ROOT TUBERS (ROOT TUBES) - THICKNING OF THE LATERAL (dahlia) OR SUPPLEMENTARY ROOTS (chlorophytum), CONNECTED WITH THE DEPOSITS OF BATHAGES.
AIR ROOTS (EPIPHYT PLANTS) How can you explain that the roots of some plants, for example, orchids, can turn green in the light? 1) Orchids live in dark rainforests. 2) To increase the intensity of the process of photosynthesis in the cells of the roots, chlorophyll is formed
Aerial roots adventitious roots ARISING IN PLANTS FOR stalks high above the ground Roots -PRITSEPKI -PRISOSKI values of the roots (haustoria) to absorb moisture directly from the air ROOTS -PODPORKI stilted ROOTS ROOTS RESPIRATORY typical for vines and epiphytes (of the family. Orchidaceae, Araceae and DR.). SOME TROPICAL TREES (FOR EXAMPLE, THE INDIAN BANYAN) VK hang from the branches, reach the soil and become roots support. IN MANGRA TREES V.K. - HANDLING, CREATING A SUPPORT IN SMOOTHY SOIL, AS WELL AS RESPIRATORY, WHICH BEGIN TO GROW UNDERGROUND, AND THEN EXIT ON
SUPPLEMENTARY ROOTS ARISING IN PLANTS ON Above-Ground Shoots HIGH ABOVE THE EARTH AND SERVING TO ABSORATE MOISTURE DIRECTLY FROM THE AIR
SUPPORTING ROOTS. MEET IN LARGE TREES (ELM, BEECH, POPLAR, TROPICAL, ETC.). REPRESENT THE LATERAL ROOTS. ON THE LATERAL ROOTS, WHICH PASS NEAR THE SOIL SURFACE, FLAT TRIANGULAR AND VERTICAL Aboveground branches, which resemble the boards leaning against the tree, develop. STRETCH, OR CONTRACTIVE ROOTS. SOME PLANTS SHARP REDUCTION OF THE ROOT IN THE LONGITUDINAL DIRECTION AT ITS BASE (FOR EXAMPLE, IN PLANTS WHICH HAVE BULBS). RETRACTED ROOTS ARE DISTRIBUTED IN POTATO-SEED PLANTS. THEY CONDITION A TIGHT ADHESION TO THE EARTH OF SOCKETS (FOR EXAMPLE, AT A PALANOUS, Dandelion, etc.), THE UNDERGROUND POSITION OF THE ROOT NECK AND VERTICAL ROOT, PROVIDE NONGROUND. IN THIS WAY, THE ROOTED ROOTS HELP THE RUNS TO FIND THE BEST LOOKING DEPTH IN THE SOIL. VINTAGE ROOTS IN THE ARCTIC PROVIDE EXPERIENCE OF AN ADVERSE WINTER PERIOD WITH FLOWER BUDS.
THE BANYAN LIFE FORM is amazing. In mature plants, long aerial roots form from the trunk and branches, which reach the ground and take root, providing the ficus with water and nutrients. Over time, the roots thicken and turn into additional trunks, supports for a single dense crown. Thus, the banyan tree grows in breadth, "strides" with new trunks in all directions from the central trunk, and over time a grove or forest is formed from one tree. A banyan tree can cover an area of up to several hectares. There is evidence that some old banyan trees, which are hundreds (and even thousands) of years old, reached a height of more than 30 meters and more than 400 meters in circumference, formed up to 1300 side trunks and up to 3000 aerial roots. It is estimated that under the crown of one such tree, about 10,000 people could fit. A humid tropical climate is favorable for the development of banyans. The most famous Bengal ficus banyan trees are found in India (Calcutta, Bangalore, Adyar, Auroville) and the USA (Hawaii, Florida). http: // ficusweb. ru / banyan. html
OPEN BEAMS BETWEEN XYLEM AND FLOEMA THERE ARE CAMBIUM (dicotyledonous and gymnosperms) CLOSED BEAMS BETWEEN XYLEM AND FLOEMA NO KAMBIUM (monocotyledonous)
IN VASCULAR PLANTS THE MOVEMENT OF SUBSTANCES IS CARRIED OUT BY TWO SYSTEMS: XYLEME (WATER AND MINERAL SALTS) AND FLOEME (ORGANIC SUBSTANCES). The movement of substances along the xylem is directed from the roots to the aerial parts of the plant; along the phloem, nutrients move from the leaves. ONE OF THE MOST IMPORTANT MECHANISMS OF TRANSPORTATION OF SUBSTANCES IN A PLANT IS OSMOSIS - THIS IS THE TRANSFER OF SOLVENT MOLECULES (FOR EXAMPLE, WATER) FROM AREAS WITH A HIGHER CONCENTRATION IN A REGION WITH A REGION WITH A MORE CONCENTRATION. This process is similar to normal diffusion, but faster. Numerically, osmosis is characterized by osmotic pressure - the pressure that must be applied to prevent osmotic flow of water into the solution. THE CELL WALL IS WATER PERMEABLE. IN PLANTS THE ROLE OF SEMI-PERMEABLE MEMBRANES IS PLAYED BY PLASMATIC MEMBRANE AND TONOPLAST (MEMBRANE SURROUNDING VACUOL). If the cell comes into contact with a hypertonic solution (that is, a solution in which the concentration of water is less than in the cell itself), then water begins to leave the cell outside. This process is called plasmolysis. At the same time, the cell shrinks. Plasmolysis is reversible: if such a cell is placed in a hypotonic solution (with a higher water content), then water will begin to flow inside, and the cell will swell again. In this case, the inner parts of the cell (protoplast) exert pressure on the cell wall. In a plant cell, the swelling is stopped by a rigid cell wall. Animal cells have no rigid walls, and plasma membranes are too delicate; a special mechanism is needed to regulate osmosis.
THE MAIN MASS OF WATER IS ABSORBED BY YOUNG ZONES OF PLANTS ROOTS IN THE AREA OF ROOT HAIRS - TUBULAR EPIDERMIS GROWTH. Thanks to them, the surface that absorbs water is significantly increased. Water enters the root through osmosis and moves up to the xylem along the apoplast (along the cell walls), symplast (along the cytoplasm and plasmodesmata), and also through the vacuoles. It should be noted that there are stripes in the cell walls, called Caspari belts. They consist of a waterproof suberin and prevent the movement of water and substances dissolved in it. In these places, water is forced to pass through the plasma membranes of cells; it is believed that in this way plants are protected from the penetration of toxic substances, pathogenic fungi, etc.
WATER RISE IN XYLEM APPEARSLY OCCURS BY EVAPORATION OF WATER IN THE LEAVES. IN THE PROCESS OF EVAPORATION IN THE CROWN, A LACK OF WATER IS FORMED. THE SURFACE TENSION IN THE VESSELS OF THE XILEM IS ABLE TO PULL UP THE WHOLE POST OF WATER, CREATING A MASS FLOW. The rate of water rise is about 1 m / h (up to 8 m / h in tall trees); to raise water to the top of a tall tree, a pressure of about 40 atm is required. It should be borne in mind that capillary effects alone are capable of raising water to a height of no more than 3 m. A SECOND IMPORTANT FORCE PARTICIPATING IN WATER RISE IS THE ROOT PRESSURE. It is 1–2 atm (in exceptional cases - up to 8 atm). This value, of course, is not enough to single-handedly ensure the movement of liquid, but its contribution in many plants is beyond doubt.
>> Pod absorption by the root
§ 15. Absorption of water by the root
Make sure that the roots are absorbing water with solutes from the soil... Cut off a houseplant balsam or a three to four week old sunflower or bean seedling so that a stump remains 2-3 cm high.On the stump we put a rubber tube 3 cm long, pour some water into it and put a glass tube 20-25 cm high on its upper end curved as shown in the figure 29 .
After a while, the water in the glass tube rises and flows out. Where does the water flowing out of the tube come from? The root absorbs water from the soil. Through the vessels of the root, water under pressure enters the remaining stump, and then into the tube. This pressure is called root pressure. Root pressure facilitates the flow of water from root into the stem.
If the soil in a pot with a cut plant is poured with warm water, the water will begin to rise faster through the tube and flow out of it. And after watering the soil with very cold water, the water will stop rising. Thus, water uptake by the root is temperature dependent. Cold water is poorly absorbed by the roots. Therefore, you should not water the plants with cold water.
Plants cannot live without water. Water is part of cells plants. It is necessary for the swelling and germination of seeds. But especially a lot of water is required for adult plants during growth. When the fruits begin to ripen, the water requirement of the plants usually decreases.
It is better to water the cultivated plants of our gardens, parks, flower gardens and squares in the evening when the heat subsides. At this time, water is well absorbed into the soil and evaporates less.
When watering, the watering can should be kept close to the surface of the plot or pot with a plant so that the water jet does not erode the soil 30 ... It is better to water the plant rarely, but abundantly, than often, but little by little. For irrigation of crops and plantings on large areas, collective and state farms use special sprinklers.
In many areas of our country land you have to irrigate. For this, they construct irrigation canals, arrange ponds and reservoirs. To retain moisture in the soil and protect crops from dry winds, forest belts are planted.
1. How can you prove that the roots absorb water from the soil?
2. Why can't indoor plants be watered with cold water?
3. How to properly water the plants?
4. How are crops and planting in large areas provided with water? 5. What measures are taken to retain moisture in the farms in your area?
Korchagina V.A., Biology: Plants, bacteria, fungi, lichens: Textbook. for 6 cl. wednesday shk. - 24th ed. - M .: Education, 2003 .-- 256 p.: Ill.
Lesson content lesson outline support frame lesson presentation accelerative methods interactive technologies Practice tasks and exercises self-test workshops, trainings, cases, quests home assignments discussion questions rhetorical questions from students Illustrations audio, video clips and multimedia photos, pictures, charts, tables, schemes humor, jokes, jokes, comics parables, sayings, crosswords, quotes Supplements abstracts articles chips for the curious cheat sheets textbooks basic and additional vocabulary of terms others Improving textbooks and lessonsbug fixes in the tutorial updating a fragment in the textbook elements of innovation in the lesson replacing obsolete knowledge with new ones For teachers only perfect lessons calendar plan for the year methodological recommendations of the discussion program Integrated lessonsWater exchange in plants consists of three stages: 1) the absorption of water by the roots, 2) its movement through the vessels, 3) transpiration, that is, the evaporation of water by leaves. Each of these stages, in turn, consists of several interrelated processes.
Although small amounts of water can be absorbed by the aboveground parts of plants, almost all water and mineral salts enter the body of higher plants through the root system from the soil.
The main function of the root is to absorb water from the soil with mineral nutrients dissolved in it.
The zone of the most intense absorption of water coincides with the zone of development of root hairs, due to which the absorption surface of the root increases. For example, a 4-month-old rye plant grown under optimal conditions had an average of 13,800,000 roots with a total surface area of 232 m2, the number of living root hairs 14 billion with a surface area of 399 m2. The total area of roots and root hairs was 631 m2 and they were located in 0.05 m3 of soil. In this case, the total surface area of the entire root system was 130 times the surface area of the aerial parts of the same plant. Hairless epidermal cells absorb water at the same rate per unit surface as cells carrying root hairs. Above the zone of root hairs, the rate of water absorption decreases due to suberization of cells. However, water is partially transported through the corked root areas. In plants with mycorrhiza, the latter also serves as an additional absorbing surface, especially in the older parts of the root.
* The growth of the root, its branching continues throughout the life of the plant organism, that is, it is practically unlimited. Meristems - educational tissues - are located at the apex of each root. The proportion of meristematic cells is relatively high.
Root growth is fast. It is believed that one rice plant in favorable conditions can form up to 5 km of new roots per day. Due to this growth of the root system, an additional 1.5 liters of water can be supplied to the plant. Of great importance is the phenomenon of hydrotropism, in which the growth of the root system, as it were, proceeds from the more desiccated layers of the soil to the more humid ones. Depending on the type of plant, the distribution of the root system in the soil is different. In some plants, the root system penetrates to a great depth, in others it mainly spreads in width.
Fig. 5.
A - longitudinal section: 1 - root cap; 2 - meristem; 3 - stretch zone; 4 - zone of root hairs; 5 - branching zone; B - cross section: 1 - rhizoderm; 2 - root hair, 3 - parenchyma, 4 - endoderm; 5 - Caspari belts, 6 - pericycle, 7 - phloem, 8 - xylem. Arrows - paths of movement of substances absorbed from the external solution. Solid arrows - the path of the solution along the symplast; intermittent - along the apoplast.
From a physiological point of view, the root system is heterogeneous. Not the entire root surface is involved in water absorption. Several zones are distinguished in each root (Fig. 5), however, not all zones are always expressed equally clearly. The end of the root is protected from the outside by a root cap resembling a rounded cap, consisting of living thin-walled oblong cells. The root cap serves as a protection for the growing point. The cells of the root cap slough off, which reduces friction and promotes root penetration into the soil. The meristematic zone is located under the root cap. The meristem consists of numerous small, rapidly dividing, densely packed cells, almost entirely filled with protoplasm. The next zone is the stretch zone. Here the cells increase in volume (stretch). At the same time, differentiated sieve tubes appear in this zone. This is followed by the zone of root hairs. With a further increase in the age of the cells, as well as the distance from the root tip, the root hairs disappear, and the cutinization and suberization of the cell membranes begins. Water absorption occurs mainly by the cells of the stretch zone and the zone of root hairs. A certain amount of water can also flow through the corked root zone. This is mainly seen in trees. In this case, water penetrates through the lentils or wounds.
The root surface in this zone of root hairs is covered with rhizoderma. It is a single-layer tissue with two types of cells that form and do not form root hairs. Root hairs grow by stretching the cell membrane, which occurs at a high rate (0.1 mm / h). The presence of calcium is very important for their growth.
In most plants, rhizoderm cells have thin walls. Following the rhizoderma up to the pericycle are the cells of the cortex. The cortex is composed of several layers of parenchymal cells. An important feature of the cortex is the development of a system of large intercellular spaces. On the border of the cortex and the central cylinder, one layer of tightly adjacent cells develops - endoderm, which is characterized by the presence of Caspari belts. The cytoplasm in endoderm cells adheres tightly to the cell membranes. With aging, the entire inner surface of endoderm cells, with the exception of the passage cells, becomes covered with suberin. With further aging, more layers may be superimposed on top. Apparently, it is the endoderm cells that serve as the main physiological barrier for the movement of both water and nutrients. Conductive root tissues are located in the central cylinder. Typically, the absorbent zone is about 5 cm long. Its value depends on the growth rate of the root as a whole. The slower the root grows, the shorter the absorption zone.
Root systems change under the influence of certain conditions. The influence of temperature on the formation of root systems is well shown. As a rule, the optimum temperature for the growth of root systems is slightly lower compared to the growth of aerial organs of the same plant. Still, a strong drop in temperature noticeably inhibits root growth and promotes the formation of thick, fleshy, little branching root systems.
Soil moisture is of great importance for the formation of root systems. The distribution of roots along the soil horizons is often determined by the distribution of water in the soil. Usually, in the first period of the life of a plant organism, the root system grows extremely intensively and, as a result, rather reaches the more humid layers of the soil. Some plants develop shallow root systems. Located close to the surface, highly branching roots intercept precipitation. In dry areas, deep and shallow rooting plant species often grow side by side. The former provide themselves with moisture due to deep soil layers, the latter due to the assimilation of precipitation. Aeration is essential for the development of root systems. It is the lack of oxygen that is the reason for the poor development of root systems in swampy soils. Plants adapted to growing on poorly aerated soils have a system of intercellular spaces in the roots, which, together with the intercellular spaces in the stems and leaves, make up a single ventilation system.
Nutritional conditions are of great importance. It is shown that the introduction of phosphorus fertilizers promotes the deepening of root systems, and the introduction of nitrogen fertilizers - their enhanced branching.
Phylogenetically, the root arose later than the stem and leaf - in connection with the transition of plants to life on land and probably originated from root-like underground branches. The root has no leaves or buds arranged in a certain order. It is characterized by apical growth in length, its lateral ramifications arise from internal tissues, the growth point is covered with a root cap. The root system is formed throughout the life of a plant organism. Sometimes the root can serve as a place of deposition in the supply of nutrients. In this case, it is modified.
Types of roots
The main root is formed from the embryonic root during seed germination. Lateral roots extend from it.
Adventitious roots develop on stems and leaves.
Lateral roots are branches of any root.
Each root (main, lateral, adventitious) has the ability to branch, which significantly increases the surface of the root system, and this contributes to better strengthening of the plant in the soil and improving its nutrition.
Types of root systems
There are two main types of root systems: pivotal, with a well-developed main root, and fibrous. The fibrous root system consists of a large number of adventitious roots of the same size. The entire mass of roots consists of lateral or adventitious roots and looks like a lobe.
The highly branched root system forms a huge absorbing surface. For example,
- the total length of the roots of winter rye reaches 600 km;
- length of root hairs - 10,000 km;
- total root surface - 200 m 2.
This is many times the area of the above-ground mass.
If the plant has a well-expressed main root and adventitious roots develop, then a mixed root system is formed (cabbage, tomato).
External structure of the root. Internal structure of the root
Root zones
Root cap
The root grows in length at its tip, where young cells of the educational tissue are located. The growing part is covered with a root cap that protects the root tip from damage and makes it easier for the root to move through the soil during growth. The latter function is carried out due to the property of the outer walls of the root cap to be covered with mucus, which reduces friction between the root and soil particles. They can even push apart soil particles. The cells of the root cap are alive and often contain starch grains. The cells of the cap are constantly renewed due to division. Participates in positive geotropic reactions (direction of root growth towards the center of the Earth).
The cells of the division zone are actively dividing; the length of this zone is not the same in different species and in different roots of the same plant.
A stretch zone (growth zone) is located behind the division zone. The length of this zone does not exceed a few millimeters.
As the linear growth is completed, the third stage of root formation begins - its differentiation, a zone of differentiation and specialization of cells (or a zone of root hairs and absorption) is formed. In this zone, the outer layer of the epiblema (rhizoderm) with root hairs, the layer of the primary cortex and the central cylinder are already distinguished.
Root hair structure
Root hairs are highly elongated outgrowths of the outer cells that cover the root. The number of root hairs is very large (per 1 mm 2 from 200 to 300 hairs). Their length reaches 10 mm. Hair is formed very quickly (in young apple seedlings in 30-40 hours). Root hairs are short-lived. They die off after 10-20 days, and new ones grow on the young part of the root. This ensures the development of new soil horizons by the root. The root grows continuously, forming more and more new areas of root hairs. The hairs can not only absorb ready-made solutions of substances, but also contribute to the dissolution of some soil substances, and then suck them in. The area of the root, where the root hairs have died off, is able to absorb water for some time, but then it becomes covered with a cork and loses this ability.
The hair sheath is very thin, which facilitates the absorption of nutrients. Almost the entire hair cell is occupied by a vacuole surrounded by a thin layer of cytoplasm. The nucleus is at the top of the cell. A mucous membrane forms around the cell, which promotes adhesion of root hairs with soil particles, which improves their contact and increases the hydrophilicity of the system. The absorption is facilitated by the release of acids (carbonic, malic, citric) by the root hairs, which dissolve mineral salts.
Root hairs also play a mechanical role - they serve as a support for the root apex, which passes between soil particles.
Under a microscope, on a transverse section of the root in the absorption zone, its structure at the cellular and tissue levels is visible. On the surface of the root is the rhizoderm, below it is the bark. The outer layer of the cortex is the exoderm, inward from it is the main parenchyma. Its thin-walled living cells perform a storage function, carry out solutions of nutrients in a radial direction - from the suction tissue to the vessels of the wood. They also synthesize a number of organic substances vital for the plant. The inner layer of the cortex is endoderm. Nutrient solutions from the cortex into the central cylinder through the endoderm cells pass only through the protoplast of the cells.
The bark surrounds the central cylinder of the root. It borders on a layer of cells that retain their ability to divide for a long time. This is the pericycle. Pericycle cells give rise to lateral roots, adventitious buds and secondary educational tissues. Inward from the pericycle, in the center of the root, are the conductive tissues: bast and wood. Together they form a radial conductive bundle.
The conductive system of the root conducts water and minerals from the root to the stem (upward current) and organic matter from the stem to the root (downward current). It consists of vascular fibrous bundles. The main components of the bundle are sections of the phloem (along which substances move to the root) and xylem (along which substances move from the root). The main conducting elements of phloem are sieve tubes, xylems are trachea (vessels) and tracheids.
Root vital processes
Root water transport
Absorption of water by root hairs from the soil nutrient solution and carrying it in the radial direction along the cells of the primary cortex through the passage cells in the endoderm to the xylem of the radial conducting bundle. The intensity of water absorption by the root hairs is called the suction force (S), it is equal to the difference between osmotic (P) and turgor (T) pressure: S = P-T.
When the osmotic pressure is equal to the turgor pressure (P = T), then S = 0, water stops flowing into the cell of the root hair. If the concentration of substances in the soil nutrient solution is higher than inside the cell, then the water will leave the cells and plasmolysis will occur - the plants will wither. This phenomenon is observed in dry soil conditions, as well as with excessive application of mineral fertilizers. Inside the root cells, the sucking force of the root increases from the rhizoderm towards the central cylinder, so the water moves along the concentration gradient (i.e., from a place with a higher concentration of it to a place with a lower concentration) and creates root pressure, which raises the water column along the vessels of the xylem forming an upward current. This can be found on leafless spring trunks when "sap" is being collected, or on cut tree stumps. The outflow of water from wood, fresh stumps, leaves is called "crying" of plants. When the leaves bloom, they also create a sucking force and attract water to themselves - a continuous column of water is formed in each vessel - capillary tension. The root pressure is the lower motor of the water current, and the sucking force of the leaves is the upper one. This can be confirmed with the help of simple experiments.
Absorption of water by the roots
Target: figure out the basic function of the root.
What do we do: a plant grown on wet sawdust, shake off its root system and put its roots in a glass of water. Pour a thin layer of vegetable oil over the water to protect it from evaporation and mark the level.
What we observe: in a day or two, the water in the container dropped below the mark.
Result: therefore, the roots sucked in the water and brought it up to the leaves.
One more experiment can be done to prove the absorption of nutrients by the root.
What do we do: cut off the stem of the plant, leaving a stump 2-3 cm high.Place a rubber tube 3 cm long on the stump, and put a curved glass tube 20-25 cm high on the upper end.
What we observe: the water in the glass tube rises and flows out.
Result: this proves that the root absorbs water from the soil into the stem.
Does the water temperature affect the rate of water absorption by the root?
Target: find out how temperature affects the work of the root.
What do we do: one glass should be with warm water (+ 17-18 ° C), and the other with cold (+ 1-2 ° C).
What we observe: in the first case, water is released abundantly, in the second - little, or completely stops.
Result: this is proof that temperature has a profound effect on the functioning of the root.
Warm water is actively absorbed by the roots. Root pressure rises.
Cold water is poorly absorbed by the roots. In this case, the root pressure drops.
Mineral nutrition
The physiological role of minerals is very important. They are the basis for the synthesis of organic compounds, as well as factors that change the physical state of colloids, i.e. directly affect the metabolism and structure of the protoplast; serve as catalysts for biochemical reactions; affect cell turgor and protoplasm permeability; are the centers of electrical and radioactive phenomena in plant organisms.
It has been established that the normal development of plants is possible only if the nutrient solution contains three non-metals - nitrogen, phosphorus and sulfur and - and four metals - potassium, magnesium, calcium and iron. Each of these elements has an individual meaning and cannot be replaced by another. These are macronutrients, their concentration in the plant is 10 -2 –10%. For the normal development of plants, microelements are needed, the concentration of which in the cell is 10 -5 -10 -3%. These are boron, cobalt, copper, zinc, manganese, molybdenum, etc. All these elements are present in the soil, but sometimes in insufficient quantities. Therefore, mineral and organic fertilizers are applied to the soil.
The plant grows and develops normally if all the necessary nutrients are contained in the environment surrounding the roots. Soil is such a medium for most plants.
Breathing roots
For normal growth and development of the plant, it is necessary that fresh air flows to the root. Let's check if this is so?
Target: does the root need air?
What do we do: take two identical vessels with water. We will place developing seedlings in each vessel. We saturate the water in one of the vessels with air every day using a spray bottle. Pour a thin layer of vegetable oil on the surface of the water in the second vessel, as it delays the flow of air into the water.
What we observe: after a while, the plant in the second vessel will stop growing, wither, and eventually die.
Result: the death of the plant occurs due to the lack of air necessary for the respiration of the root.
Root modifications
Some plants store reserve nutrients in the roots. They accumulate carbohydrates, mineral salts, vitamins and other substances. Such roots grow strongly in thickness and acquire an unusual appearance. Both the root and the stem are involved in the formation of root crops.
Roots
If storage substances accumulate in the main root and at the base of the stem of the main shoot, root crops (carrots) are formed. Root-forming plants are mainly biennials. In the first year of life, they do not bloom and accumulate many nutrients in root crops. On the second, they bloom quickly, using accumulated nutrients and form fruits and seeds.
Root tubers
In dahlia, reserve substances accumulate in the adventitious roots, forming root tubers.
Bacterial nodules
The lateral roots of clover, lupine, and alfalfa are peculiarly changed. Bacteria settle in the young lateral roots, which facilitates the assimilation of gaseous nitrogen in the soil air. Such roots take the form of nodules. Thanks to these bacteria, these plants are able to live in nitrogen-poor soils and make them more fertile.
Stilted
Stilted roots develop near the tidal ramp. They hold large leafy shoots high above the water on unsteady muddy ground.
Air
Tropical plants living on tree branches develop aerial roots. They are often found in orchids, bromeliads, and some ferns. Aerial roots hang freely in the air, not reaching the ground and absorbing moisture that falls on them from rain or dew.
Retracting
In bulbous and corms, such as crocuses, among the numerous filamentous roots, there are several thicker, so-called retracting roots. Shrinking, such roots pull the corms deeper into the soil.
Columnar
The ficus develops columnar aerial roots, or support roots.
Soil as a habitat for roots
The soil for plants is the medium from which it receives water and nutrients. The amount of mineral substances in the soil depends on the specific characteristics of the parent rock, the activity of organisms, on the life of the plants themselves, on the type of soil.
Soil particles compete with the roots for moisture, retaining it on their surface. This is the so-called bound water, which is subdivided into hygroscopic and film water. It is held by the forces of molecular attraction. The moisture available to the plant is represented by capillary water, which is concentrated in the small pores of the soil.
Antagonistic relations develop between the moisture and the air phase of the soil. The more large pores in the soil, the better the gas regime of these soils, the less moisture the soil retains. The most favorable water-air regime is maintained in structural soils, where water and air are located simultaneously and do not interfere with each other - water fills capillaries inside structural aggregates, and air fills large pores between them.
The nature of the interaction between the plant and the soil is largely related to the absorption capacity of the soil - the ability to retain or bind chemical compounds.
The microflora of the soil decomposes organic matter to simpler compounds, participates in the formation of the soil structure. The nature of these processes depends on the type of soil, the chemical composition of plant residues, the physiological properties of microorganisms and other factors. Soil animals take part in the formation of the soil structure: annelids, insect larvae, etc.
As a result of the totality of biological and chemical processes in the soil, a complex complex of organic substances is formed, which is united by the term "humus".
Aquatic culture method
What salts the plant needs, and what effect they have on its growth and development, was established by experiment with aquatic crops. The aquatic culture method is the cultivation of plants not in soil, but in an aqueous solution of mineral salts. Depending on the goal in the experiment, you can exclude an individual salt from the solution, reduce or increase its content. It was found that fertilizers containing nitrogen promote the growth of plants containing phosphorus - the early ripening of fruits, and those containing potassium - the fastest outflow of organic matter from the leaves to the roots. In this regard, fertilizers containing nitrogen are recommended to be applied before sowing or in the first half of summer, containing phosphorus and potassium - in the second half of summer.
With the help of the method of aquatic cultures, it was possible to establish not only the plant's need for macronutrients, but also to clarify the role of various microelements.
Currently, there are cases when plants are grown using hydroponics and aeroponics.
Hydroponics - growing plants in containers filled with gravel. The nutrient solution containing the necessary elements is fed into the vessels from the bottom.
Aeroponics is an aerial plant culture. With this method, the root system is in the air and is automatically (several times within an hour) sprayed with a weak solution of nutrient salts.
This material can be used to conduct an olympiad in biology in grades 7-11. Assignments of various types with a system for evaluating results have been developed. In the test tasks of parts I and III, for each correct answer, the participant receives 1 point. In the test tasks of Part II, the participant receives 2 points for each correct answer. In the tests in Part IV, you need to fill in the matrices in accordance with the requirements described in the conditions. The features of assessment are described in the text for each assignment individually. The results for each task are summarized.
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Biology Olympiad for schoolchildren, grade 7 (school tour)
Part I. You are offered test tasks that require you to choose only one answer out of four possible. The maximum number of points that can be collected is 15 (1 point for each test task).
Part II.
I. relapsing fever.
II. typhus.
III. malaria.
IV. tularemia.
V. hepatitis.
a) II, IV;
b) I, IV, V;
c) I, II, IV;
d) II, III, IV, V.
I. kidney formation.
II. leaf formation.
a) II, III, IV;
b) I, II, IV, V;
c) I, III, IV, V;
d) I, II, III, IV.
I. the root will die.
II. the whole plant will die.
a) III, IV, V;
b) III, V;
c) I, IV, V;
d) II, IV, V- The root can:
I. absorb water with solutes. +
II. fix the plants in the soil. +
III. grow at the expense of the interstitial meristem.
IV. synthesize amino acids, hormones, alkaloids. +
V. form scaly leaves on old root sites.
a) I, II, III;
b) I, II, IV; +
c) II, IV, V;
d) I, III, V. - Aboveground type of seed germination is typical for:
I. beans. +
II. peas.
III. linden. +
IV. maple. +
V. oats.
a) I, II, IV;
b) II, III, V;
c) I, III, IV; +
d) II, IV, V.
Part III.
- Starch grains are leukoplasts with starch accumulated in them. +
- The same plant can live in any environment of life.
- Algae live only in the aquatic environment of life.
- Plants are able to live only in the environment to which they are adapted.
- Dandelion is the name of a plant species.
- Photosynthesis is the formation of organic substances and oxygen from carbon dioxide and water in the light.
- In the leaf pulp of many plants, columnar and spongy tissues can be distinguished.
Part IV.
- [swing. 4 points] Examining the plants in the backyard, the scientist determined that some of them (1–4) showed signs of starvation for a number of nutrients (A – D):
Olympiad for schoolchildren in biology, grade 8 (school tour)
Grading system for individual assignments and work as a whole
In the test tasks of parts I and III, for each correct answer, the participant receives 1 point. In the test tasks of Part II, the participant receives 2 points for each correct answer. In the tests in Part IV, you need to fill in the matrices in accordance with the requirements described in the conditions. The features of assessment are described in the text for each assignment individually. The results for each task are summarized. The duration of the tour is 2 astronomical hours (120 minutes).
Part I. You are offered test tasks that require you to choose only one answer out of four possible. The maximum number of points that can be collected is 20 (1 point for each test task).
Part II. You are offered test items with one answer out of four possible, but requiring multiple prior choice. The maximum number of points that can be collected is 10 (2 points for each test task).
- If you cut off (trim) the tip of the main root:
I. the root will die.
II. the whole plant will die.
III. the root will stop growing in length.
IV. the plant will survive but be weak.
V. lateral and adventitious roots will begin to grow.
a) III, IV, V;
b) III, V;
c) I, IV, V;
d) II, IV, V.
I. spiders.
II. ticks.
III. solpug.
IV. haymakers.
V. scorpions.
a) II;
b) II, III;
c) I, IV;
d) I, II, III, V.
I. corals.
II. sponges.
III. ascidians.
IV. rotifers.
V. barnacles.
a) I, II, III, IV;
b) I, II, III, V;
c) I, III, IV;
d) I, II, III, IV, V.
I. perch.
II. sturgeon.
III. sharks.
IV. lampreys.
V. lancelet.
a) I, II, III, IV;
b) III, IV, V;
c) II, III, V;
d) II, IV, V.
I. stellate sturgeon.
II. sardine.
III. pink salmon.
IV. rudd.
V. river eel.
a) II, III, V;
b) III, V;
c) I, III, V;
d) I, II, III, V.
Part III. You are offered test tasks in the form of judgments, with each of which you must either agree or reject. Please enter a yes or no answer. The maximum number of points that can be collected is 10.
- Liver mosses are lower plants.
- Gametes in mosses are formed as a result of meiosis.
- After fertilization, the ovules turn into seeds, and the ovary into a fruit.
Part IV. You are offered test tasks that require matching. The maximum number of points that can be collected is indicated for each task individually.
1. [swing. 4 points] Examining the plants in the backyard, the scientist determined that some of them (1–4) showed signs of starvation for a number of nutrients (A – D):
1) Pale yellow tissue between veins in young leaves. Older leaves are later affected in a similar manner. Low plant vigor.
2) Dying off of apical buds, twisted deformed leaves. Black rot in beets and carrots.
3) Delayed flowering in ornamental plants, lack of growth. Violet color of leaves and stems. The tendency to curl and turn over the leaves.
4) Weak growth, dwarfism, scleromorphism. The shoot / root ratio is shifted in favor of the roots. Premature yellowing of old leaves.
Correlate these symptoms with the causes of their occurrence.
Elements: A - phosphorus; B - nitrogen, C - iron and D - boron.
- swing. 4 points] The biologist set up an experiment. He poured a sucrose solution of various concentrations into 7 test tubes: 0.2 M; 0.3M; 0.4M; 0.5M; 0.6M; 0.7M and 1M. In each of the test tubes I placed a block cut from a potato tuber. The original length of all blocks was 40 mm. After 30 minutes, the sticks were removed and measured. According to the measurements, the researcher built a histogram, where C is the concentration of the sucrose solution in test tubes 1-7, and l is the change in the length of the potato sticks depending on the concentration of the solution. Then, using a histogram, he determined the concentration of the isotonic solution.
Tube number | |||||||
Isotonic solution |
Olympiad for schoolchildren in biology, grade 9 (school tour)
Grading system for individual assignments and work as a whole
In the test tasks of parts I and III, for each correct answer, the participant receives 1 point. In the test tasks of Part II, the participant receives 2 points for each correct answer. In the tests in Part IV, you need to fill in the matrices in accordance with the requirements described in the conditions. The features of assessment are described in the text for each assignment individually. The results for each task are summarized. The duration of the tour is 2 astronomical hours (120 minutes).
Part I. You are offered test tasks that require you to choose only one answer out of four possible. The maximum number of points that can be collected is 25 (1 point for each test task).
-
a) green euglena;
b) ciliate shoe;
c) amoeba;
d) staphylococcus aureus.
- Honeybee color vision spectrum:
a) the same as that of a person;
b) shifted to the infrared part of the spectrum;
c) shifted to the ultraviolet part of the spectrum;
d) much wider than that of humans, on both sides of the spectrum. - The development of larvae from eggs laid by roundworms occurs:
a) at a temperature of 37 O C, high concentration of CO 2 , in two weeks;
b) at a temperature of 20-30 O C, high concentration of CO 2 , in two weeks;
c) at a temperature of 37 O C, high concentration O 2 , in a week;
d) at a temperature of 20-30 O C, high concentration O 2 , in two weeks. - a) the digestive system;
b) the excretory system;
c) circulatory system;
d) the nervous system. - a) chest and abdomen;
b) breasts;
c) the cephalothorax and abdomen;
d) the cephalothorax. - The worker bees are:
- a) with urine;
b) through the salt glands;
c) through the pores in the skin;
d) with excrement. - a) only the female;
b) only a male;
c) both parents take turns; - a) eagles;
b) pelicans;
c) ostriches;
d) African weavers. - Of the listed organisms, the most progressive structural features are:
a) amoeba;
b) earthworm;
c) hydra;
d) Volvox. - The complication of the circulatory system corresponds to the evolution of chordates among the following animals:
a) toad - rabbit - crocodile - shark;
b) shark - frog - crocodile - rabbit;
c) shark - crocodile - frog - rabbit;
d) crocodile - shark - toad - dog. - The greatest species diversity of the inhabitants of the World Ocean is observed:
a) on coral reefs;
b) in the open ocean in the tropics;
c) in the polar regions;
d) in deep-sea depressions. - It is believed that when information is transferred from short-term memory to long-term memory, information is lost:
a) 5%;
b) 10%;
c) 50%;
d) more than 90%. - a) slightly acidic;
b) neutral;
c) slightly alkaline;
d) alkaline. - a) proteins;
b) amino acids;
c) lipids;
d) carbohydrates. - a) glycerol;
b) fatty acids;
c) monosaccharides;
d) amino acids.
a) tocopherol;
b) pyridoxine;
c) riboflavin;
d) folic acid.
a) Pchini's little body;
b) Meissner's little body;
d) Krause flask.- a) measles;
b) tick-borne encephalitis;
c) rubella;
d) diphtheria. - The food chain is:
- a) freshwater ecosystems;
b) natural ecosystems of the land;
d) agrocenoses. -
a) birds;
b) rodents;
c) ungulates;
d) a person. -
Part II.
- Bacteria cause diseases:
I. relapsing fever.
II. typhus.
III. malaria.
IV. tularemia.
V. hepatitis.
a) II, IV;
b) I, IV, V;
c) I, II, IV;
d) II, III, IV, V. - Roots can perform functions:
I. kidney formation.
II. leaf formation.
III. vegetative propagation.
IV. absorption of water and minerals.
V. synthesis of hormones, amino acids and alkaloids.
a) II, III, IV;
b) I, II, IV, V;
c) I, III, IV, V;
d) I, II, III, IV. - If you cut off (trim) the tip of the main root:
I. the root will die.
II. the whole plant will die.
III. the root will stop growing in length.
IV. the plant will survive but be weak.
V. lateral and adventitious roots will begin to grow.
a) III, IV, V;
b) III, V;
c) I, IV, V;
d) II, IV, V. - Among arachnids, development with metamorphosis is typical for:
I. spiders.
II. ticks.
III. solpug.
IV. haymakers.
V. scorpions.
a) II;
b) II, III;
c) I, IV;
d) I, II, III, V. - Animals that lead an attached (sedentary) lifestyle, but have free-swimming larvae, are:
I. corals.
II. sponges.
III. ascidians.
IV. rotifers.
V. barnacles.
a) I, II, III, IV;
b) I, II, III, V;
c) I, III, IV;
d) I, II, III, IV, V. - Chorda persists throughout life in:
I. perch.
II. sturgeon.
III. sharks.
IV. lampreys.
V. lancelet.
a) I, II, III, IV;
b) III, IV, V;
c) II, III, V;
d) II, IV, V. - Spawns only once in a lifetime:
I. stellate sturgeon.
II. sardine.
III. pink salmon.
IV. rudd.
V. river eel.
a) II, III, V;
b) III, V;
c) I, III, V;
d) I, II, III, V.
I. gas exchange.
II. thermoregulation.
III. storing water.
IV. accumulation of urine.
V. digestion.
a) I, III, IV;
b) I, IV;
c) I, II, IV, V;
d) I, II, III, IV.
I. water.
II. glucose.
III. urea.
IV. hemoglobin.
V. plasma albumin.
a) I, II, III;
b) I, III, IV, V;
c) II, IV, V;
d) IV, V.
I. proteins and peptides.
II. derivatives of nucleotides.
IV. derivatives of amino acids.
a) III, IV, V;
b) I, III, IV, V;
c) III, V;
d) II
Part III.
- Starch grains are leukoplasts with starch accumulated in them.
- After fertilization, the ovules turn into seeds, and the ovary into a fruit.
- In all invertebrates, fertilization is external.
- The hemolymph of insects performs the same functions as the blood of vertebrates.
- All representatives of the order of reptiles have a three-chambered heart.
- Domestic animals tend to have larger brains than their wild ancestors.
- The first crocodiles were land reptiles.
- Live birth is a characteristic feature of all mammals.
Part IV. Participants are offered test tasks that require matching. The maximum number of points that can be collected is indicated for each task individually. Contestants must complete the answer matrices in accordance with the requirements of the assignments.
- [ swing. 4 points] Examining the plants in the backyard, the scientist determined that some of them (1–4) showed signs of starvation for a number of nutrients (A – D):
1) Pale yellow tissue between veins in young leaves. Older leaves are later affected in a similar manner. Low plant vigor.
2) Dying off of apical buds, twisted deformed leaves. Black rot in beets and carrots.
3) Delayed flowering in ornamental plants, lack of growth. Violet color of leaves and stems. The tendency to curl and turn over the leaves.
4) Weak growth, dwarfism, scleromorphism. The shoot / root ratio is shifted in favor of the roots. Premature yellowing of old leaves.
Correlate these symptoms with the causes of their occurrence.
Elements: A - phosphorus; B - nitrogen, C - iron and D - boron.
- (max. 4 points) The biologist set up an experiment. He poured a sucrose solution of various concentrations into 7 test tubes: 0.2 M; 0.3M; 0.4M; 0.5M; 0.6M; 0.7M and 1M. In each of the test tubes I placed a block cut from a potato tuber. The original length of all blocks was 40 mm. After 30 minutes, the sticks were removed and measured. According to the measurements, the researcher built a histogram, where C is the concentration of the sucrose solution in test tubes 1-7, and l is the change in the length of the potato sticks depending on the concentration of the solution. Then, using a histogram, he determined the concentration of the isotonic solution.
Indicate in the matrix with an "X" the number of the tube with isotonic solution.
Tube number | |||||||
Isotonic solution |
Olympiad for schoolchildren in biology, grade 10 (school tour)
Grading system for individual assignments and work as a whole
In the test tasks of parts I and III, for each correct answer, the participant receives 1 point. In the test tasks of Part II, the participant receives 2 points for each correct answer. In the tests in Part IV, you need to fill in the matrices in accordance with the requirements described in the conditions. The features of assessment are described in the text for each assignment individually. The results for each task are summarized. The duration of the tour is 2 astronomical hours (120 minutes).
Part I. You are offered test tasks that require you to choose only one answer out of four possible. The maximum number of points that can be collected is 30 (1 point for each test task).
- a) lily of the valley;
b) lilac;
c) rye;
d) plantain. - Seeds without endosperm in:
a) castor bean;
b) linden;
c) tomato;
d) plantain ditties. - a) adventitious roots;
b) root hairs;
c) main roots;
d) air tubers. - Fertility is typical for:
a) pears;
b) pineapple;
c) banana;
d) quince. - a) buckthorn buckthorn;
b) field sow thistle;
c) trembling aspen; - Unlike roundworms, annelids have developed:
a) the digestive system;
b) the excretory system;
c) circulatory system;
d) the nervous system. - Insects have wings on the dorsal side:
a) chest and abdomen;
b) breasts;
c) the cephalothorax and abdomen;
d) the cephalothorax. - The worker bees are:
a) females who laid eggs and started caring for their offspring;
b) females whose sex glands are not developed;
c) young females capable of laying eggs in a year;
d) males that have developed from unfertilized eggs. - Marine iguanas living in the Galapagos Islands remove excess salt from the body:
a) with urine;
b) through the salt glands;
c) through the pores in the skin;
d) with excrement. - At the ostrich, the rhea incubates eggs and takes care of the chicks:
a) only the female;
b) only a male;
c) both parents take turns;
d) adoptive parents, in whose nest eggs were thrown. - The largest nests among birds are built by:
a) eagles;
b) pelicans;
c) ostriches;
d) African weavers. - Cellulose that has entered the human gastrointestinal tract:
a) is not cleaved due to the absence of a specific enzyme;
b) is partially broken down by bacteria in the large intestine;
c) it is cleaved by salivary α-amylase;
d) is cleaved by pancreatic α-amylase. - What is the reaction of the environment in the duodenum:
a) slightly acidic;
b) neutral;
c) slightly alkaline;
d) alkaline. - Hormones are not known that are derived from:
a) proteins;
b) amino acids;
c) lipids;
d) carbohydrates. - In the process of digestion, the digestion of proteins is broken down to:
a) glycerol;
b) fatty acids;
c) monosaccharides;
d) amino acids. - Symptoms such as lesions of the oral mucosa, peeling skin, cracked lips, tearing, photophobia indicate a deficiency:
a) tocopherol;
b) pyridoxine;
c) riboflavin;
d) folic acid. - Cold-responsive skin receptor:
a) Pchini's little body;
b) Meissner's little body;
c) the nerve plexus around the hair follicle;
d) Krause flask. - Viral diseases do not include:
a) measles;
b) tick-borne encephalitis;
c) rubella;
d) diphtheria. - The food chain is:
a) the sequence of organisms in a natural community, each element of which is food for the next;
b) the sequential passage of food through various sections of the digestive tract;
c) dependence of plants on herbivores, and their, in turn, on predators;
d) the totality of all food connections in the ecosystem. - Continuous human intervention is required for existence:
a) freshwater ecosystems;
b) natural ecosystems of the land;
c) ecosystems of the World Ocean;
d) agrocenoses. -
- a) taxonomy;
b) history;
c) paleontology;
d) evolution. - a) ray-finned;
b) cross-finned;
c) whole-headed;
d) lungs. -
a) divergences;
b) convergence;
c) parallelism;
d) random coincidence. - a) mitosis;
b) meiosis;
c) fertilization;
d) pollination. - a) zygotes;
b) a vegetative cell;
c) somatic cells; - a) tRNA;
b) DNA;
c) rRNA;
d) mRNA. - Circular DNA is characteristic of:
a) mushroom kernels;
b) bacterial cells;
c) animal nuclei;
d) plant nuclei. - a) chromatography;
b) centrifugation;
c) electrophoresis;
d) autoradiography
Part II. You are offered test items with one answer out of four possible, but requiring multiple prior choice. The maximum number of points that can be collected is 20 (2 points for each test task).
- Chorda persists throughout life in:
I. perch.
II. sturgeon.
III. sharks.
IV. lampreys.
V. lancelet.
a) I, II, III, IV;
b) III, IV, V;
c) II, III, V;
d) II, IV, V. - Spawns only once in a lifetime:
I. stellate sturgeon.
II. sardine.
III. pink salmon.
IV. rudd.
V. river eel.
a) II, III, V;
b) III, V;
c) I, III, V;
d) I, II, III, V. - Allantois performs the function of amniotes:
I. gas exchange.
II. thermoregulation.
III. storing water.
IV. accumulation of urine.
V. digestion.
a) I, III, IV;
b) I, IV;
c) I, II, IV, V;
d) I, II, III, IV. - In the renal glomerulus, the following are normally practically not filtered:
I. water.
II. glucose.
III. urea.
IV. hemoglobin.
V. plasma albumin.
a) I, II, III;
b) I, III, IV, V;
c) II, IV, V;
d) IV, V.
I. density.
II. number.
III. degree of isolation.
a) I, II, V;
b) I, IV, V;
c) II, V;
d) II, III, IV.
I. wolf.
II. Lynx.
III. jaguar.
IV. cheetah.
V. bear.
a) II, III, IV, V;
b) I, IV;
c) I, II, III, V;
d) II, III, V.
I. squirrel.
II. ferret.
III. arctic fox.
IV. lemming.
V. green toad.
a) I, II, III, IV;
b) II, III, IV, V;
c) III, IV;
d) III, IV, V.
I. gills of fish and gills of crayfish.
a) I, III, IV, V;
b) I, II, IV, V;
c) I, II, III, V;
d) I, II, III, IV.
I. chitin.
II. amylose.
III. glycogen.
IV. cellulose.
V. amylopectin.
a) I, II, IV;
b) I, II, III, IV;
c) II, IV, V;
d) III, IV, V.- In the human body, hormonal functions are performed by compounds:
I. proteins and peptides.
II. derivatives of nucleotides.
III. cholesterol derivatives.
IV. derivatives of amino acids.
V. derivatives of fatty acids.
a) III, IV, V;
b) I, III, IV, V;
c) III, V;
d) II.
Part III. You are offered test tasks in the form of judgments, with each of which you must either agree or reject. Please enter a yes or no answer. The maximum number of points that can be collected is 15.
- The hemolymph of insects performs the same functions as the blood of vertebrates.
- All representatives of the order of reptiles have a three-chambered heart.
- Domestic animals tend to have larger brains than their wild ancestors.
- The first crocodiles were land reptiles.
- Live birth is a characteristic feature of all mammals.
- Unlike most mammals, humans are characterized by the presence of seven cervical vertebrae and two occipital condyles.
- In the human gastrointestinal tract, all proteins are completely digested.
- Hypervitaminosis is known only for fat-soluble vitamins.
- The human brain uses about twice as much energy per gram of weight as that of a rat.
- With hard physical work, the body temperature can rise to 39 degrees.
- Viral infections are usually fought with antibiotics.
- Nutrient cycling can be studied by introducing radioactive markers into natural or artificial ecosystems.
Part IV.
Functions | |||||
Compound |
3.
|
School Olympiad in Biology Grade 11 (school tour)
Grading system for individual assignments and work as a whole
In the test tasks of parts I and III, for each correct answer, the participant receives 1 point. In the test tasks of Part II, the participant receives 2 points for each correct answer. In the tests in Part IV, you need to fill in the matrices in accordance with the requirements described in the conditions. The features of assessment are described in the text for each assignment individually. The results for each task are summarized. The duration of the tour is 2 astronomical hours (120 minutes).
Part I. You are offered test tasks that require you to choose only one answer out of four possible. The maximum number of points that can be collected is 35 (1 point for each test task).
- Symptoms such as lesions of the oral mucosa, peeling skin, cracked lips, tearing, photophobia indicate a deficiency:
a) tocopherol;
b) pyridoxine;
c) riboflavin;
d) folic acid. - Cold-responsive skin receptor:
a) Pchini's little body;
b) Meissner's little body;
c) the nerve plexus around the hair follicle;
d) Krause flask. - Viral diseases do not include:
a) measles;
b) tick-borne encephalitis;
c) rubella;
d) diphtheria. - The food chain is:
a) the sequence of organisms in a natural community, each element of which is food for the next;
b) the sequential passage of food through various sections of the digestive tract;
c) dependence of plants on herbivores, and their, in turn, on predators;
d) the totality of all food connections in the ecosystem. - Continuous human intervention is required for existence:
a) freshwater ecosystems;
b) natural ecosystems of the land;
c) ecosystems of the World Ocean;
d) agrocenoses. - Under natural conditions, the natural carriers of the plague pathogen are:
a) birds;
b) rodents;
c) ungulates;
d) a person. - In the vast forests of the North, so-called concentrated felling using heavy equipment is often carried out, which leads to:
a) to the replacement of forest ecosystems with swamp ones;
b) to desertification or complete destruction of ecosystems;
c) to an increase in the share of tree species that are more valuable from the point of view of the economy;
d) to the process of converting organic residues in the soil into humus. - Leaves of succulents - plants in arid habitats - are characterized by:
a) reduced stomata; undifferentiated mesophyll; lack of cuticles; developed aerenchyma;
b) frequent dissection, lack of mechanical tissue;
c) thick cuticle; powerful wax bloom; cells with large vacuoles; submerged stomata;
d) well-developed sclerenchyma; the predominance of bound water. - Of these organisms, the prokaryote super-kingdom includes:
a) green euglena;
b) ciliate shoe;
c) amoeba;
d) staphylococcus aureus. - Two breeds of dogs, for example, lapdog and German shepherd, are animals:
a) one type, but with different external characteristics;
b) two species, one genus and one family;
c) two species, two genera, but one family;
d) one species, but living in different environmental conditions. - A science that studies the development of living nature from prints and fossils found in the earth's crust:
a) taxonomy;
b) history;
c) paleontology;
d) evolution. - The first terrestrial vertebrates evolved from fish:
a) ray-finned;
b) cross-finned;
c) whole-headed;
d) lungs. - The body contours of a flying squirrel, a marsupial flying squirrel, and a woolly wing are very similar. This is a consequence:
a) divergences;
b) convergence;
c) parallelism;
d) random coincidence. - The number of chromosomes during sexual reproduction in each generation would double if the process did not form during evolution:
a) mitosis;
b) meiosis;
c) fertilization;
d) pollination. - One of the provisions of the cell theory says:
a) during cell division, chromosomes are capable of self-doubling;
b) new cells are formed during the division of the original cells;
c) the cytoplasm of cells contains various organelles;
d) cells are capable of growth and metabolism. - With parthenogenesis, the body develops from:
a) zygotes;
b) a vegetative cell;
c) somatic cells;
d) an unfertilized egg. - A molecule serves as a matrix for translation:
a) tRNA;
b) DNA;
c) rRNA;
d) mRNA. - Circular DNA is characteristic of:
a) mushroom kernels;
b) bacterial cells;
c) animal nuclei;
d) plant nuclei. - It is possible to divide cells, organelles or organic macromolecules according to their density using the method:
a) chromatography;
b) centrifugation;
c) electrophoresis;
d) autoradiography. - Nucleic acid monomers are:
a) nitrogenous bases;
b) nucleosides;
c) nucleotides;
d) dinucleotides. - Magnesium ions are part of:
a) vacuoles;
b) amino acids;
c) chlorophyll;
d) cytoplasm. - In the process of photosynthesis, the source of oxygen (by-product) is:
a) ATP
b) glucose;
c) water;
d) carbon dioxide. - Of the plant cell components, the tobacco mosaic virus infects:
a) mitochondria;
b) chloroplasts;
c) the core;
d) vacuoles. - Of these proteins, the enzyme is:
a) insulin;
b) keratin;
c) thrombin;
d) myoglobin. - In chloroplasts of plant cells, light-harvesting complexes are located
a) on the outer membrane;
b) on the inner membrane;
c) on the thylakoid membrane;
d) in the stroma. - Non-allelic interaction of genes during dihybrid crossing can give splitting in the second generation:
a) 1: 1;
b) 3: 1;
c) 5: 1;
d) 9: 7. - The spike inflorescence is typical for:
a) lily of the valley;
b) lilac;
c) rye;
d) plantain. - Seeds without endosperm in:
a) castor bean;
b) linden;
c) tomato;
d) plantain ditties. - Root cones are very thickened:
a) adventitious roots;
b) root hairs;
c) main roots;
d) air tubers. - Fertility is typical for:
a) pears;
b) pineapple;
c) banana;
d) quince. - Root-sprouting plants include:
a) buckthorn buckthorn;
b) field sow thistle;
c) trembling aspen;
d) all the listed plants. - Unlike roundworms, annelids have developed:
a) the digestive system;
b) the excretory system;
c) circulatory system;
d) the nervous system. - Insects have wings on the dorsal side:
a) chest and abdomen;
b) breasts;
c) the cephalothorax and abdomen;
d) the cephalothorax. - The worker bees are:
a) females who laid eggs and started caring for their offspring;
b) females whose sex glands are not developed;
c) young females capable of laying eggs in a year;
d) males that have developed from unfertilized eggs. - Marine iguanas living in the Galapagos Islands remove excess salt from the body:
a) with urine;
b) through the salt glands;
c) through the pores in the skin;
d) with excrement
Part II. You are offered test items with one answer out of four possible, but requiring multiple prior choice. The maximum number of points that can be collected is 20 (2 points for each test task).
- Chorda persists throughout life in:
I. perch.
II. sturgeon.
III. sharks.
IV. lampreys.
V. lancelet.
a) I, II, III, IV;
b) III, IV, V;
c) II, III, V;
d) II, IV, V. - Spawns only once in a lifetime:
I. stellate sturgeon.
II. sardine.
III. pink salmon.
IV. rudd.
V. river eel.
a) II, III, V;
b) III, V;
c) I, III, V;
d) I, II, III, V. - Allantois performs the function of amniotes:
I. gas exchange.
II. thermoregulation.
III. storing water.
IV. accumulation of urine.
V. digestion.
a) I, III, IV;
b) I, IV;
c) I, II, IV, V;
d) I, II, III, IV. - In the renal glomerulus, the following are normally practically not filtered:
I. water.
II. glucose.
III. urea.
IV. hemoglobin.
V. plasma albumin.
a) I, II, III;
b) I, III, IV, V;
c) II, IV, V;
d) IV, V. - Each population is characterized by:
I. density.
II. number.
III. degree of isolation.
IV. independent evolutionary destiny.
V. the nature of the spatial distribution.
a) I, II, V;
b) I, IV, V;
c) II, V;
d) II, III, IV. - Predators that usually hunt from ambush include:
I. wolf.
II. Lynx.
III. jaguar.
IV. cheetah.
V. bear.
a) II, III, IV, V;
b) I, IV;
c) I, II, III, V;
d) II, III, V. - Of these animals, the tundra biocenosis includes:
I. squirrel.
II. ferret.
III. arctic fox.
IV. lemming.
V. green toad.
a) I, II, III, IV;
b) II, III, IV, V;
c) III, IV;
d) III, IV, V. - Similar organs that have evolved over the course of evolution:
I. gills of fish and gills of crayfish.
II. butterfly wings and bird wings.
III. tendrils of peas and tendrils of grapes.
IV. hair of mammals and feathers of a bird.
V. cactus spines and hawthorn spines.
a) I, III, IV, V;
b) I, II, IV, V;
c) I, II, III, V;
d) I, II, III, IV. - Of these polymers, unbranched polymers include:
I. chitin.
II. amylose.
III. glycogen.
IV. cellulose.
V. amylopectin.
a) I, II, IV;
b) I, II, III, IV;
c) II, IV, V;
d) III, IV, V. - In the human body, hormonal functions are performed by compounds:
I. proteins and peptides.
II. derivatives of nucleotides.
III. cholesterol derivatives.
IV. derivatives of amino acids.
V. derivatives of fatty acids.
a) III, IV, V;
b) I, III, IV, V;
c) III, V;
d) II.
Part III. You are offered test tasks in the form of judgments, with each of which you must either agree or reject. Please enter a yes or no answer. The maximum number of points that can be collected is 20.
1. The hemolymph of insects performs the same functions as the blood of vertebrates.
- All representatives of the order of reptiles have a three-chambered heart.
- Domestic animals tend to have larger brains than their wild ancestors.
- The first crocodiles were land reptiles.
- Live birth is a characteristic feature of all mammals.
- Unlike most mammals, humans are characterized by the presence of seven cervical vertebrae and two occipital condyles.
- In the human gastrointestinal tract, all proteins are completely digested.
- Hypervitaminosis is known only for fat-soluble vitamins.
- The human brain uses about twice as much energy per gram of weight as that of a rat.
- With hard physical work, the body temperature can rise to 39 degrees.
- Viral infections are usually fought with antibiotics.
- Nutrient cycling can be studied by introducing radioactive markers into natural or artificial ecosystems.
- Succulents easily tolerate dehydration.
- Succession after deforestation is an example of secondary succession.
- Gene drift can play the role of an evolutionary factor only in very small populations.
- Genetic information in all living organisms is stored in the form of DNA.
- One codon corresponds to each amino acid.
- In prokaryotes, translation and transcription processes occur simultaneously and in the same place.
- The largest molecules in living cells are DNA molecules.
- All hereditary diseases are associated with mutations in the chromosomes.
Part IV. You are offered test tasks that require matching.
- Establish in what sequence (1 - 5) the process of DNA reduplication takes place.
-
Establish a correspondence between an organic compound (A - D) and the function it performs (1 - 5).
Functions | |||||
Compound |
3.
It is known that a high content of salts in the soil creates a sharply negative water potential in it, which leads to a violation of the flow of water into the cells of the plant root, and sometimes to damage to cell membranes. Choose adaptations found in plants growing in saline soils.
01. Root cells of salt-tolerant plants are capable of absorbing salts and excreting them through secreting cells on the leaves and stem;
02. The content of cells of salt-tolerant plants has a more negative water potential compared to cells of other plants;
03. The cells are characterized by a high salt content;
04. The cytoplasm of the cells of these plants has a low hydrophilicity;
05. The cytoplasm of cells of salt-tolerant plants is highly hydrophilic;
06. Cells of salt-tolerant plants are characterized by less negative water potential than in the surrounding soil solution;
07. The intensity of photosynthesis in plants growing on saline soils is low;
08. The intensity of photosynthesis in these plants is high.
|
Answer matrix
in biology (school tour)
2011-12 academic year year. __7th grade
Exercise 1.
1-10 | ||||||||||
11-15 |
Task 2.
Task 3.
right. "YES" | ||||||||||
wrong "no" |
Task 4. (4 points)
Answer matrix
for the tasks of the All-Russian Olympiad for schoolchildren
in biology. 2011-12 academic year year. __8th grade
Exercise 1.
1-10 | ||||||||||
11-20 |
Task 2.
1-10 |
Task 3.
right. "YES" | ||||||||||
wrong "no" |
Task 4.1. (4 points)
Tube number | ||||||||||||||||
Isotonic solution |
Answer matrix
for the tasks of the All-Russian Olympiad for schoolchildren
in biology. 2011-12 academic year year. ____9__ class
Exercise 1.
1-10 | ||||||||||
11-20 | ||||||||||
21-25 |
Task 2.
1-10 |
Task 3.
right. "YES" | |||||||||||||||
wrong "no" |
Task 4.1. (4 points)
Tube number | ||||||||||||||||
Isotonic solution |
Answer matrix
for the tasks of the All-Russian Olympiad for schoolchildren
in biology. 2011-12 academic year year. ___Grade 10
Exercise 1.
1-10 | ||||||||||
11-20 | ||||||||||
21-30 |
Task 2.
1-10 |
Task 3.
right. "YES" | |||||||||||||||
wrong "no" |
Task 4.1. (5 points)
- (5 points)
Answer matrix
for the tasks of the All-Russian Olympiad for schoolchildren
in biology. 2011-12 academic year year. ___Grade 11
Exercise 1.
1-10 | ||||||||||
11-20 | ||||||||||
21-30 | ||||||||||
31-35 |
Task 2.
1-10 |
Task 3.
right. "YES" | |||||||||||||||
wrong "no" | |||||||||||||||
right. "YES" | |||||||||||||||
wrong "no" |
Task 4.1. (5 points)
Subsequence | |||||
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