Ministry of Education, Science and Youth of the Republic of Crimea

Republican contest of nature projects for elementary school students "Pathfinder"

Section: "Plants Around Us"

WHY IN AUTUMN THE LEAVES CHANGE THEIR COLOR?

Work completed:

Zhilinskaya Daria Sergeevna,

4th grade student

municipal treasury

educational institution

"Kholmovskaya average

comprehensive school"

Bakhchisarai district

Republic of Crimea

Head:

Kolesnikova Svetlana Nikolaevna,

primary school teacher

municipal treasury

educational institution

"Kholmovskaya average

comprehensive school"

Bakhchisarai district

Republic of Crimea

simferopol - 2015

CONTENT

INTRODUCTION ___________________________________________________________ 3

LITERATURE REVIEW _______________________________________ 5

1. Causes of discoloration of leaves in trees and shrubs ________ 5

   Scientists about the color change of leaves ___________________________ 6

   Features of deciduous trees in deciduous trees and shrubs _______7

RESEARCH METHODS AND RESULTS _____________________ 9

2.1.   Proof of the presence of chlorophyll pigment in the sheet _________________ 9

2.2. Proof of Anthocyanin Pigment on Sheet __________________ 9

2.3. Proof of carotene and xanthophyll in the leaf ______________ 10

2.4. Obtaining watercolors from a solution of anthocyanin and chlorophyll ____ 11

CONCLUSIONS ___________________________________________________________12

LIST OF USED LITERATURE AND INTERNET SOURCES _______________________________________________________ 14

APPENDICES

INTRODUCTION

“It's a sad time!” Eye charm!

I am pleased with your sad beauty

I love the lush nature of wilting,

In scarlet and gold clad forests ... "

/ A.S. Pushkin /

We have always been interested to find out where in autumn there are so many bright and varied colors. Indeed, in the summer all the leaves are green. Why in the fall foliage changes color, and the leaves become yellow, red, crimson. Last year, in the lesson “The World around us,” we studied seasonal changes in nature. Brought from the tour a lot of colorful leaves.It became interesting for us to explore:why do the leaves on the trees fall in different colors in the fall?

Objective: to study the causes of discoloration of leaves in trees and shrubs before leaf fall.

To achieve this goal, the following were settasks:

1. To study the literature on the topic.

2. Observe the color of deciduous trees and shrubs in the autumn.

3. Explore why in autumn leaves on trees and shrubs change color.

4. Conduct a studyon the selection of coloring pigments from the sheet and find them application.

4. Find out why trees and shrubs drop leaves for the winter.

5. Draw conclusions.

Object of study: fallen leaves of trees and shrubs.

Subject of study:   discoloration of leaves in trees and shrubs.

Hypothesis: i suppose that the leaves change color on the trees and shrubs, because the tree is sick and the leaves are afraid of the cold.

Research Methods. Analysis of scientific literature, experiments.

LITERATURE REVIEW

1. Causes of discoloration of leaves in trees and shrubs

After studying the scientific literature, we found that the leaves initially contain substances such as chlorophyll, xanthophyll, carotene, anthocyanins.

The green substance in the leaves of trees is called chlorophyll. Together, in the summer, chlorophyll and sunlight help trees process their main source of nutrition - carbon dioxide. So, sunlight and chlorophyll are the “knife and fork” that help trees absorb the air we exhale, and it, in turn, helps trees grow large and strong. Chlorophyll is easily destroyed. But in the summer, under the influence of sunlight, it quickly recovers. When autumn comes and the light becomes less and less, chlorophyll is destroyed and does not have time to recover. The leaves get rid of the green pigment, and their true color appears for a while.
The substance xanthophyllum gives the leaves a yellow color, carotene - orange. Bright red, crimson shades give the leaves pigments anthocyanins.
In summer, these pigments are not visible, we see only green chlorophyll. With the onset of cold weather, the nutrients collected in the leaves of the trees enter the branches and trunk. Since nutrient production stops in winter, chlorophyll decomposes. With its disappearance, other pigments that are constantly present in the sheet become visible. And we enjoy the variety of colors of the trees.

1. Scientists about changing color of leaves

Back in the XVIII century. Geneva pastor Jean Senebier pondered the question: why is this green world green? Having studied the effect of sunlight, he showed that thanks to the process of oxygen formation and carbon dioxide absorption that occurs in the green leaf, the plant feeds, and through it, the animal world. Thus was made one of the greatest discoveries. But the question of the green color of the leaves remained open.[ 1; 7 ]

Natural scientists around the world were looking for an answer. For more than 35 years, the great Russian scientist Kliment Arkadyevich Timiryazev gave the study of the green leaf, storing future rays of the sun. The crucial role of chlorophyll pigment in the process of photosynthesis and the importance of plants on Earth were discovered.

And on the Internet we found new facts on this issue.The professor of biology at the University of London, Imperial College Thomas Dering, in the course of research on the change in the autumn color of leaves, came to the conclusion that thereby plants are trying to protect themselves from a number of dangerous pests. Studying the colors that insect pests “prefer”, primarily aphids, the scientist found that when laying eggs in the fall, they avoid the red gamut. In this case, the preference for pests is green and yellow. Moreover, Dering found that with an increased concentration of pests, leaves can turn red even in those trees that usually have yellow foliage in the fall. Traditionally, red in nature denotes danger. But scientists from the University of North Carolina in Charlotte under the leadership of Emily Habink found that the whole thing is in the soil. If the earth is poor in nitrogen, the leaves will produce more red pigment. With its help, the foliage will last longer on the branches, and the tree will be able to pick up more useful substances from it. Thus, it will at least make up for the nitrogen deficiency. But when the tree does not need such a recharge, then nature leaves the leaves yellow. Thanks to this discovery of scientists, the quality of the soil can now be determined by the color of the leaves. If in the autumn the forest turned into beautiful red tones, it means that not everything is safe with the earth in these places.[ 4 ]

Consequently,there are other theories of scientists about the color change of leaves in the fall. It is interesting to know!

1. Features of leaf fall in different trees and shrubs

One of the most characteristic phenomena of the arrival of autumn is leaf fall. Why do deciduous trees and shrubs drop their foliage every year? It is necessary to find out whether leaf fall is a biological phenomenon for deciduous trees and shrubs, or whether it is due to a change in climate. If the deciduous tree is transplanted into a warm room, then it will discard the foliage despite the good temperature conditions. That is, leaf fall is not a consequence of adverse conditions for trees and shrubs, but is a plant development cycle. You can see that in the place where the leaf is attached to a branch of a deciduous tree, there is a “leaf pad”. When leaf fall begins, the leaves easily separate from the tree and remain hanging on the vascular bundles that connect the leaf to the tree. They serve to supply substances from the root of a deciduous tree to the leaves. When this connection between the foliage and the tree is broken, the branches of the deciduous tree lose their outfit.

Leaf fall is the adaptation of deciduous trees and shrubs to harsh conditions. If a deciduous tree remains in winter with green leaves, it will die from a lack of moisture. The significance of deciduous trees in the life of deciduous trees is especially pronounced when compared with conifers. Coniferous trees (especially pine and spruce) - tolerate drought well. In addition, the needles evaporate very little water than the foliage of deciduous trees. Therefore, conifers can remain green all year. The amount of moisture that conifers vaporize is ten times less than that of deciduous trees. But larch behaves like a deciduous tree and evaporates moisture 5 times more than ordinary spruce and 10 times more than pine. The ability of coniferous trees to save moisture is achieved through needles. The needles have many devices for preserving moisture: thick skin, wax coating. The leaves of deciduous trees are devoid of drought-resistant devices.

In addition to the fact that deciduous trees are saved from drought due to leaf fall, in winter this saves them from a tumble. In winter, even the bare branches of trees break under the weight of snow. What would happen if snow settled on the broad leaves of deciduous trees?

With deciduous leaves, deciduous trees get rid of excess mineral salts, which become harmful to trees and shrubs. With age, the foliage of trees increases the ash content. The accumulation of minerals in deciduous trees occurs because the leaves of the tree evaporate a lot of water. It is replaced by new moisture, which contains minerals. Some of them go to the nutrition of deciduous tree, the rest remains in the leaves. Leaf fall for a deciduous tree is a normal condition for the normal growth and development of the plant. Conifers do not need such dropping of needles, since pines, spruce and other conifers evaporate very little moisture. Larch by evaporation of moisture reaches the level of deciduous trees, therefore, in a humid climate, soft needles are discarded. [4 ]

All these facts prove that leaf fall depends not only on external conditions, but is also necessary for the normal functioning of deciduous and coniferous trees and shrubs.

II. RESEARCH METHODS AND RESULTS

2.1. Proof of Chlorophyll Pigment in Sheet

In a test tube with alcohol, place a green leaf and heat over the spirit lamp. After some time, the alcohol should turn green and the leaf will be colorless.

Thus, the alcohol really turned green, and the leaf became colorless, this proves the presence of a green pigment in the leaf - chlorophyll.

2.2.   Proof of Anthocyanin Pigment in Sheet

You can verify the presence of anthocyanins in the leaves in several ways.

First: you need to boil red leaves and drop vinegar into this solution. The color of the solution will turn pink-red.

Second: grind the red leaves in a mortar with a small amount of sand, and, adding 5 ml of water, filter.

Based on this,the color of the solution in the first and second experiments confirms that anthocyanins are water-soluble red pigments found in leaves.

2.3. Proof of carotene and xanthophyll in the leaf

Add 5 ml of ethyl alcohol to the chopped green leaves, chalk on the tip of the knife and grind it in a porcelain mortar until smooth until the alcohol turns green. I put a drop of the obtained liquid on a paper with a glass rod.

In addition, after 3 - 5 minutes, colored concentric circles formed on the paper: green in the center, yellow-orange outside, which proves the presence of a green pigment - chlorophyll, a yellow pigment - xanthophyll, and orange - carotene.

2.4. Getting watercolor paints from a solution of anthocyanins and chlorophyll.[ 1 ]

We decided to use the solutions obtained in the experiments to obtain paints. For this, solutions of anthocyanins and chlorophyll of different colors were preparedby adding water. Dissolved pieces of gum in a small volume of water (glue from tree trunks). The gum solution was poured into paint molds. The resulting solutions were added to each form. Stirred. The colors are ready.

With these colors I painted a flower.

So, with the help of solutions obtained from autumn leaves of different colors, water and gum, you can prepare watercolor paints of various colors and use them in drawing.

FINDINGS

The most remarkable sign of autumn: a change in the color of the leaves.For example, who did not admire the colors of a flowering meadow, forest edge, garden and field gifts? But not everyone knows where nature has such a rich palette of colors.

Why do leaves change their color in autumn? After studying the scientific literature, we found that the leaves initially contain substances such as chlorophyll, xanthophyll, carotene, anthocyanins. Chlorophyll gives the leaves a green color, xanthophyll - yellow, anthocyanins - red, carotene - orange. In autumn, chlorophyll is destroyed, and orange, yellow and red pigments are preserved and become noticeable.

After conducting research, we were convinced that the leaves really contained coloring pigments.  And if they are contained there, then where does the soil or dangerous pests?

Our first hypothesis that trees fall sick in autumn, and therefore change the color of leaves, has not been confirmed. But we realized that the autumn color of the leaves depends on what pigment, in addition to chlorophyll, is in the leaves.

Having worked with various sources, we learned that leaf fall is a natural fall of leaves in trees and shrubs associated with preparation for winter.

Thus, our second hypothesis that the leaves are afraid of the cold and therefore fly around in the fall has not been confirmed either. But we found that it is beneficial for trees and shrubs to drop foliage in order to survive in the cold winter.

So, the leaves initially contain various coloring substances. Chlorophyll gives the leaves a green color, xanthophyll - yellow, anthocyanins - red, carotene - orange. In autumn, chlorophyll is destroyed, and orange, yellow and red pigments are preserved and become noticeable.

LIST OF LITERATURE AND INTERNET SOURCES

1.Baturitskaya N.B., Fenchuk T.D. "Amazing experiments with plants", Mn., "Nar.asvet", 1991, p. 5-8, 14-16

2. Dietrich A. “Pochemuchka”, M. “Slovo”, 1990, p. 314

3. Encyclopedia "Heroes of Russian History", M., "White City", 2006, p.395

"Forest, like a painted tower, lilac, golden, crimson"

Changing the color of the leaves is one of the first signs of autumn. A lot of bright colors in the autumn forest! Birch, ash and linden turn yellow, the leaves of the spindle tree turn pink, the patterned leaves of the mountain ash become crimson, aspen and orange leaves. What is the reason for this color diversity?

In the leaves of plants, along with green chlorophyll, other pigments are contained. In order to be convinced of this, we will do a simple experiment. First of all, we will prepare an extract of chlorophyll, as described above. Along with chlorophyll, yellow pigments are also found in alcohol. To separate them, pour a small amount of alcoholic extract (about two milliliters) into a test tube, add two drops of water and about 4 milliliters of gasoline. Water is introduced so that the separation of the two liquids is easier. After closing the tube with a stopper or finger, shake it vigorously. Soon you will notice that the lower (alcohol) layer turned golden yellow and the upper (gas) layer emerald green. The green color of gasoline is explained by the fact that chlorophyll dissolves better in gasoline than in alcohol, so when shaking it usually completely goes into the gasoline layer.

The golden yellow color of the alcohol layer is associated with the presence of xanthophyll, a substance insoluble in gasoline. Its formula is C40H56O2. By its chemical nature, xanthophyll is close to the carotene present in the roots of carrots, C40H56, so they are combined into one group - carotenoids. But carotene is also found in the leaves of green plants, only it, like chlorophyll, dissolves better in gasoline, so we don’t see it: the intense green color of chlorophyll “clogs” the yellow color of carotene, and we do not distinguish it, like xanthophyll in alcohol extractor hood. To see carotene, you need to convert the green pigment into a compound insoluble in gasoline. This can be achieved with alkali. In a test tube where xanthophyll separation occurred, add a piece of alkali (KOH or NaOH). Close the tube with a stopper and shake its contents thoroughly. After the separation of the liquids, you can see that the pattern of distribution of the pigments has changed: the lower alcohol layers turned green, and the upper - gasoline - yellow-orange, characteristic of carotene.

These experiments clearly indicate that in the green leaf, yellow pigments — carotenoids — are present simultaneously with chlorophyll. With the onset of cold weather, the formation of new chlorophyll molecules does not occur, and the old ones are rapidly destroyed. Carotenoids are resistant to low temperatures, so in the fall these pigments become clearly visible. They give the leaves of many plants a golden yellow and orange tint. What is the significance of carotenoids in plant life? It has been found that these pigments protect chlorophyll from destruction by light. In addition, by absorbing the energy of the blue rays of the solar spectrum, they transmit it to chlorophyll. This allows green plants to use solar energy more efficiently for the synthesis of organic matter.

Autumn forest is colored, however, not only in yellow tones. What is the connection between purple and crimson leaves? Along with chlorophyll and carotenoids, plant leaves contain pigments called anthocyanins. They are well soluble in water and are not found in the cytoplasm, but in the cell juice of vacuoles. These pigments are very diverse in color, which depends mainly on the acidity of the cell juice. This is easy to verify from experience.

First of all, cook an anthocyanin extract. To this end, grind leaves of an euonymus or some other plant, painted red or purple in autumn, with scissors, place in a cone, pour water and heat on an alcohol lamp. Soon the solution will turn reddish-blue from the presence of anthocyanins. Pour the obtained extract of pigments into two test tubes. Add weak hydrochloric or acetic acid to one, and ammonia solution to the other. Under the influence of acid, the solution turns pink, while in the presence of alkali - depending on the amount and concentration of this alkali - green, blue and yellow. Anthocyanins, like carotenoids, are more resistant to low temperatures than chlorophyll. Therefore, they are found in the leaves in the fall. The researchers found that the formation of anthocyanins is promoted by a high sugar content in plant tissues, a relatively low temperature and intense lighting.

The increase in sugar content in autumn leaves occurs due to hydrolysis of starch. This is important for transporting valuable nutrients from dying leaves to the interior of plants. After all, starch itself is not transportable in the plant. However, the outflow rate of sugars formed as a result of its hydrolysis from leaves at low temperatures is low. In addition, when the temperature drops, plant respiration is weakened and, therefore, only a small amount of Sugars undergoes oxidation. All these factors favor the accumulation of sugar in plant tissues, which begin to be used in the synthesis of other substances, in particular anthocyanins.

Other facts also indicate the conversion of excess sugars into anthocyanins. If the vine through ringing (removing part of the bark in the form of a ring) makes it difficult to outflow of photosynthesis products, then the leaves located above the ring become red after two to three weeks due to the accumulation of anthocyanins. At the same time, they are formed so much that the green color of chlorophyll becomes invisible.

The same is observed not only with a decrease in temperature or banding, but also with a lack of phosphorus. If, for example, tomatoes are grown on a nutrient solution devoid of this element, then the lower part of the leaves, as well as the stems, turn blue. The fact is that in the absence of phosphorus in plants, the process of oxidation of Sugars cannot be carried out without combining with the remainder of phosphoric acid the sugar molecule remains inactive. Therefore, the accumulation of excess amounts of Sugars, which are used for the synthesis of anthocyanins, occurs in plant tissues. An increase in the content of these substances leads to the turning blue of the stems and leaves of plants lacking phosphorus.

The formation of anthocyanins also depends on the intensity of light. If you take a closer look at the bright colors of trees and shrubs in autumn, you will notice that the leaves that are best lit are the crimson color. Spread the bush of euonymus, blazing with fiery colors, and you will see inside yellow, pale yellow and even green leaves. During rainy and cloudy autumn foliage lasts longer on trees, however it is not so bright due to lack of sun. Yellow tones predominate due to the presence of carotenoids, rather than anthocyanins. Low temperatures also contribute to the formation of anthocyanins. If the weather is warm, then the forest changes color slowly, but it barely hits the frost, aspen and maples immediately burn. M.M. Prishvin wrote in a miniature “The Lamps of Autumn”: “In the dark forests, the lamps of autumn lit up, another sheet on a dark background burns so brightly that it is even painful to watch. The linden is already all black, but one bright sheet of it has remained, hanging like a lantern on an invisible thread and shines. ”

Rainbow flora

If we are talking about plant pigments, we should also talk about the reasons for the variety of color of the flowers. Why do flowers need their bright, juicy coloring? Ultimately, in order to attract pollinating insects. Many plants are pollinated only by certain types of insects, so the color of the flowers often depends on what kind of insects are the color signals. The fact is that in terms of color, insects are quite capricious. Say bees, bumblebees, wasps prefer pink, purple and blue flowers, and flies usually hustle around yellow ones. The color red, many insects endowed with not too perfect vision, confused with dark gray. Therefore, in our latitudes pure red flowers are quite rare. The exception is poppy, but its petals are admixture of yellow; usually it is this shade that bees notice. Butterflies distinguish red color better than other insects - they, as a rule, pollinate red flowers of our latitudes, for example, carnations. But among tropical plants, red color is more common, and this is partly due to the fact that their flowers are not pollinated by insects, but by birds: hummingbirds or nectaries, in which vision is more developed.

It happens that in the same plant the color of flowers changes with age. This is clearly seen in the early spring plant of the lungwort: the pink color of its young flowers changes to blue as it ages. The old flowers of the honeybee bee no longer visit: they, as a rule, are pollinated and do not contain nectar. And in this case, the change of color is a signal for insects - do not waste time in vain! But in Gilya (USA) - a beautiful plant from the family of sinyukhovyh, relatives of phlox, growing in the mountains of Arizona (USA), the flowers initially have a scarlet color, which, as already noted, attracts birds. But when the hummingbirds leave the mountains, the ghili changes the color of the newly emerging flowers: they become pale red or even white.

The color of most flowers is determined by the presence of various pigments. The most common are carotenoids, fat-soluble compounds: carotene, its isomers and derivatives. In solution, they all have a pale yellow, orange or light red color. The names of carotenoids contained only in flowers are as beautiful as the coloring they impart: esholxanthin, petaloxanthin, gazaniaxantin, auroxanthin, chrysanthemoxanthin, rubichrom.

Along with carotenoids, the color of flowers is also determined by anthocyanins. The shades of these pigments are very diverse - from pink to black and purple. Despite this color diversity, all anthocyanins are arranged according to one type - they are glycosides, that is, compounds of sugar with a non-carbohydrate part, the so-called aglycone. An example is the coloring matter contained in the flowers of cornflower - anthocyanin. Its aglycone - cyanidin - one of the most common, is formed by the elimination of two glucose molecules from anthocyanin.

As already mentioned, anthocyanin pigments can change their color depending on the acidity of the medium. Recall two types of geranium, common in the middle lane: forest geranium and meadow geranium. The forest petals are pink or purple, and the meadow petals are blue. The difference in color is due to the fact that forest geranium sap is more sour. If you prepare an aqueous extract of geranium petals, either forest or meadow, and change its acidity, then in an acidic medium the solution will turn pink, and in alkaline medium - blue. The same operation can be done on the whole plant. If a blooming violet is placed under a glass bell next to a saucer, where ammonia is poured (it evaporates ammonia during evaporation), then its petals will turn green; and if instead of ammonia in the saucer there will be steaming hydrochloric acid, they will turn red.

We have already said that the same plant of the Lunaria may have flowers of different colors: pink - young and blue - old. Blue petals as they age can be explained by the indicator properties of anthocyanins. The cell sap of the plant in which the pigment is dissolved is acidic, and the cytoplasm is alkaline. Vacuoles with cell sap are separated from the cytoplasm by a membrane that is usually impermeable to anthocyanins. However, with age, defects appear in the membrane, and as a result, the pigment begins to penetrate from the vacuoles into the cytoplasm. And since the reaction here is different, the color of the flowers also changes.

To verify the validity of this viewpoint, take a bright red petal of some plant, such as geraniums, roses, and crush it between your fingers. At the same time, the contents of the cytoplasm and the vacuole will also mix, resulting in a blue leaf at the site of injury. However, it would be wrong to associate the color of anthocyanins only with their indicator properties. Recent studies have shown that it is determined by several other factors. The color of anthocyanin pigments may vary, for example, depending on which ions they are in the complex. When interacting with potassium ions, the complex acquires a purple color, and with calcium or magnesium ions, a blue one. If you cut a blooming bell and put it in a solution containing aluminum ions, the petals will turn blue. The same is observed if you combine solutions of anthocyanin and aluminum salts.

Many readers may be familiar with the novel by Alexander Dumas "Black Tulip", which tells in a dramatic way about the cultivation of a variety of tulip of an unusual black color. This is how the author of the novel describes it: “The tulip was beautiful, wonderful, magnificent; the stalk is eighteen inches high. He slenderly stretched upward between four green smooth, even as an arrow, leaves. His flower was completely black and glittered like amber. ” Almost five centuries were pursued by failures of the gardeners trying to bring a black tulip. And so, the Frisian Institute of Floriculture in The Hague made an official statement that in Holland a black tulip was obtained as a result of the successive crossing of two varieties - “The Queen of the Night” and “The Viennese Waltz”. Six Dutch research centers participated in the work. The resulting flower is perfect in its classic size.

Gardeners also want to create black roses. Such varieties have been derived that, in dim lighting, really appear black (in fact, they are dark red in color). Wild black roses grow on the Hawaiian Islands. In honor of the immortal work of Goethe "Faust", gardeners created a variety of black pansies called "Doctor Faust". Pansies, as you know, were favorite flowers - the great German poet and botanist.

The black or almost black color of the flowers is due to the presence of anthocyanins in the perianth. In addition to carotenoids and anthocyanins, other substances, including flavones and flavonols, can add color to petals. And what pigment dyes cherry orchards in milky color, does bird cherry bushes turn into snow-white drifts? It turns out that there are no white pigments in their petals. White color gives them. air. If you look under the microscope petal of bird cherry or any other white flower, you can see a lot of transparent and colorless cells, separated by large empty spaces. It is thanks to these air-filled intercellular spaces that the petals strongly reflect the light and therefore appear white. And if you crush such a petal between your fingers, then a transparent spot will appear in the place of squeezing: here the air will be forced out of the intercellular spaces.

And yet in nature there is white paint, for example, it is painted in the elegant white color of the bark of our beloved birch. This dye is called - betulin, from the Latin name of birch - Betula. Those who think that birch is the only plant with white bark are mistaken. This is not true. In Australia, eucalyptus grows flooded. It is named so because it grows in the channels of drying up rivers and in the rainy season it turns out to be standing in the water. The trunks of these eucalyptus trees have a pure white color that effectively stands out against the background of the surrounding green thickets.

The three-coniferous pine Bunge also has a white bark. This is a rare species found in nature mainly in the mountains of Central China. The plant is bred throughout the country near palaces and temples. White-trunk pines make an indelible impression. Many more interesting things could be told about the color of plants and plant pigments, which have long attracted the attention of researchers all over the world. More than 30 years ago, the famous Indian scientist T.R. Seshadri, who studied the natural dyes a lot, wrote: “Music of colors is more complex and changeable in nature than music of sounds. It is even possible that in reality it is even more refined than we suppose. ”

Green animals - reality or fantasy!

In the works of the fantastic genre, one can often read about human-like creatures of green color. The green color of these organisms, due to chlorophyll, allows them to independently synthesize organic matter from inorganic due to the energy of light. Is it possible in nature? First of all, it should be noted that on Earth there are animals that feed in this way. For example, euglena, well-known to all biologists, is green, often found in stagnant pools. Botanists consider Euglena an alga, and zoologists still traditionally attribute it to animals. What's the matter?

Euglena moves freely in the water with the help of a flagellum. This method of movement is characteristic of a number of protozoa as well as of some botanical objects, for example, zoospores of certain types of algae. Euglena contains chlorophyll, therefore, with its intensive reproduction, water in puddles becomes emerald green. The presence of chlorophyll allows it to feed on carbon dioxide like all green plants. However, if the alga is transferred to water containing some organic substances, it loses its green color and begins, like animals, to eat ready-made organic substances. Still, Euglen can not be called a typical animal, so we will look for other representatives. eating like plants with chlorophyll.

Back in the middle of the 19th century, the German zoologist T. Siebold discovered chlorophyll in the bodies of a freshwater hydra and some worms. Later it was found in organisms and other animals: hydroid polyps, jellyfish, corals, sponges. rotifers, mollusks. It has been found that some marine gastropods, feeding on siphon algae, do not digest the chloroplasts of these plants, and for a long time keep them in the body in a functionally active state. Chloroplasts of siphonous algae of the fragile codium and the web codium, entering the organism of mollusks, are not digested, but remain in it.

Attempts to free the mollusks from chloroplasts by placing them in the dark for six weeks turned out to be unsuccessful, as well as removing them from the eggs. The chloroplast-free larvae of mollusks died at an early stage of development. Inside an animal cell, chloroplasts are tightly packed and occupy a significant amount. Thanks to them, shell-less mollusks turn out to be painted intensely green.

Why did siphon algae "fall in love" with mollusks? The fact. that unlike other green algae, they do not have a cellular structure. Their large, often bizarre in body shape is one giant "cell". The word "cell" I quoted is not accidental. Although there are no cell walls in the body of siphon algae, it is hardly possible to call them single-celled organisms, but rather it is a conglomerate of not completely separated cells. This is confirmed by the presence of not one, but many cell nuclei. Such a structure was called siphon, and the algae themselves - siphon. The absence of cell walls, of course, facilitates the process of absorption of algae by animal cells.

Well, what are the chloroplasts of this plant? The body of the algae contains one or more chloroplasts. If there are many of them, they have a disc-shaped or spindle-shaped form. Singles have a mesh structure. Scientists believe that the mesh structure is created by connecting small chloroplasts with each other.

Many scientists have observed the absorption of carbon dioxide by chloroplasts in animal cells. In freshly harvested mollusks, the green elizia, the intensity of photosynthetic carbon dioxide assimilation was 55–67% of the value determined for the intact fragile codium algae, from which the mollusks acquired chloroplasts. It is curious that the content of chlorophyll per 1 gram of wet tissue mass in the alga and the animal was similar. Thanks to photosynthesis, mollusks fixed carbon dioxide throughout the 93 days of experience. True, the rate of photosynthesis gradually weakened, and by the end of the experiment it was 20–40% of the original.

In 1971, scientists observed the release of oxygen during the photosynthesis of chloroplasts, observed in the cells of tridacna. Tridaknas are typical inhabitants of tropical seas. They are especially widespread on the coral reefs of the Indian and Pacific Oceans. Giant giant clam looks like giant tremrock, sometimes reaching a length of 1.4 meters and a total weight of 200 kilograms. Tridaknas are interesting for us by their symbiosis with unicellular algae. Usually they are arranged on the bottom so that their translucent mantle jutting out between the wings of the shell faces upwards and is strongly illuminated by the sun. In its intercellular space in large numbers settle green algae. Despite its considerable size, the mollusk feeds only on substances that produce symbiotic algae.

In the Mediterranean and off the coast of France in the Atlantic there is a consolate worm, which also has green algae under the skin that synthesize organic matter from inorganic. Thanks to the activity of its “tenants”, the worm does not need additional sources of food, therefore its gastrointestinal tract has atrophied. During low tide, many convolut leaves their holes in order to sunbathe. At this time, the algae under their skin are photosynthesized intensively. Some species of these worms are completely dependent on their settlers. So, if a young worm does not "get infected" with algae, it will die of starvation. In turn, the algae settled in the body of the convolute, lose their ability to exist outside of his body. "Infection" occurs with the help of "fresh" ones that did not live in symbiosis with algae worms at the moment when the larvae of the worm emerge from the eggs. These algae, in all likelihood, are attracted by some substances secreted by the eggs of the worms.

In connection with the consideration of the functioning of chloroplasts in animal cells, the experiments of the American biochemist M. Nass, in which it was shown that chloroplasts of the siphon algae kaulerpa, charcoal alga nitella, spinach and African violet are captured by connective tissue cells (called fibroblasts) of mice . Usually in fibroblasts that swallow a foreign body (this process is called phagocytosis by scientists), a vacuole is formed around the absorbed particle. Gradually, the alien body is digested and absorbed - disappears. When chloroplasts were injected into the cells, vacuoles did not arise, and fibroblasts did not even try to digest them.

Plastids retained their structure and ability to photosynthesis for three weeks. Cells that became green due to their presence were normally divided. At the same time, the chloroplasts were spontaneously distributed among the daughter cells. Plastids that were in fibroplasts for about two days and then re-isolated remained intact. They assimilated carbon dioxide at the same rate as photosynthesizing fresh chloroplasts isolated from plants.

Suppose that in the course of evolution such creatures arise or are discovered on other planets. What should they be? Scientists believe that in such an animal, chlorophyll will be concentrated in the skin, where the light necessary for the synthesis of green pigment and for the formation of organic substances freely penetrates. The “green man” must do something the other way round: in the daytime, like a fairytale king, walk in clothes that are invisible to all, and at night, on the contrary, dress to warm up.

The problem is whether such an organism can get enough food through photosynthesis. Based on the maximum possible intensity of photosynthesis of plants in the most favorable conditions of existence, one can calculate how much organic matter the green skin of this person can form. If we assume that 1 square decimeter of a green plant synthesizes 20 milligrams of sugars in 1 hour, then 170 square decimeters of human skin accessible to the sun’s rays will be able to form 3.4 grams during this time. For a 12-hour day, the amount of organic matter will be 40.8 grams. About 153 calories of energy will be concentrated in this mass. This amount is clearly not enough to meet the energy needs of the human body, which are 2000-4000 calories per day.

We take into account that the "green man" does not need to think about food and be too active, because the food itself enters his body from skin chloroplasts. It is not difficult to conclude that the lack of exercise and a sedentary lifestyle will make it look like an ordinary plant. In other words, it will be very difficult to distinguish a “green man” from a prickly pear.

The researchers' calculations show that in order to form a sufficient amount of organic matter, during the course of evolution, the “green man” should increase the surface of its skin 20 times. This can occur due to an increase in the number of folds and processes. To do this, he will need to acquire the likeness of the leaves. If this happens, it will become very inactive and even more like a plant.

Thus, the existence of large photosynthetic animals and humans on Earth and in space is hardly possible. Scientists believe that in any biological system, even remotely resembling the biosphere of the Earth, there must necessarily exist plant-like organisms that provide food and energy to themselves and animals. In the second half of the XIX century, it was established that the energy of sunlight is assimilated and transformed with the help of the green pigment chlorophyll.

Based on the experiments, it can be said that the green color of chlorophyll is determined by the presence of a metal atom in it, regardless of whether it is magnesium, copper or zinc. Modern science has confirmed the correctness of the views of K.A. Timiryazev is of relatively great importance for the photosynthesis of the red rays of the solar spectrum. It turned out that the utilization rate of red light during photosynthesis is higher than that of blue rays, which are also absorbed by chlorophyll. Red rays, according to K.A. Timiryazev play a fundamental role in the process of creation and the creation of life.

As it is known, plants absorb carbon dioxide, which is added to a five-carbon substance called ribulese di-phosphate, where later it later participates in many other reactions. The study of the characteristics of photosynthesis in different plants will certainly contribute to the expansion of human capabilities in managing their photosynthetic activity, productivity and yield. In general, photosynthesis is one of the fundamental processes of life, on which a large part of modern plant fauna on the surface of the earth is based.

A change in leaf color is one of the first signs of autumn. Many bright colors in the autumn forest! Birches, ash-trees and lindens turn yellow, the leaves of euonymus turn pink, patterned rowan leaves, aspen leaves turn crimson-red, orange and crimson leaves. What is the reason for this color diversity?

The leaves of plants along with green chlorophyll contain yellow pigments - carotenoids. With the onset of cold weather, the formation of new chlorophyll molecules does not occur, and the old ones are quickly destroyed.

Carotenoids are resistant to low temperatures, so these pigments become well visible in the fall. They give the leaves of many plants a golden yellow and orange tint.

Autumn forest is colored, however, not only in yellow tones. What is the reason for the purple and purple leaf color?

Along with chlorophyll and carotenoids in the leaves of plants there are pigments, which are called anthocyanins. They are well soluble in water and are not contained in the cytoplasm, but in the cell sap of vacuoles. These pigments are very diverse in color, which depends mainly on the acidity of the cell sap.

Anthocyanins, like carotenoids, are more resistant to low temperatures than chlorophyll. Therefore, they are found in the leaves in autumn.

Researchers have found that the high content of sugars in plant tissues, relatively low temperatures and intense lighting contribute to the formation of anthocyanins.

The increase in the content of sugars in autumn leaves occurs due to the hydrolysis of starch. This is important for transporting valuable nutrients from dead leaves to the inner parts of plants.

After all, the starch itself is not transportable in the plant. However, the outflow rate of leaf sugars resulting from its hydrolysis at low temperatures is low.

In addition, when the temperature drops, the respiration of plants is weakened and, therefore, only a small amount of sugars undergo oxidation.

All these factors favor the accumulation of sugars in plant tissues, which are beginning to be used in the synthesis of other substances, in particular anthocyanins.

The formation of anthocyanins also depends on the light intensity. If you look closely at the bright colors of trees and shrubs in the fall, you will notice that the leaves that are best illuminated are mostly of purple color.

Spread the bush of euonymus burning with fiery colors, and you will see yellow, pale yellow and even green leaves inside.

During rainy and cloudy autumn, foliage lasts longer in the trees, but it is not so bright due to lack of sun. Yellow tones are predominant, due to the presence of carotenoids, rather than anthocyanins. Low temperatures also contribute to the formation of anthocyanins.

If the weather is warm, the forest changes its color slowly, but the frost hardly hits, as aspens and maples immediately burn out

MBOU Temkinskaya Municipal Secondary School

MO "Tyomkinsky district" of the Smolensk region

Research project

Secrets of the autumn leaf

Students completed grade 2:

Tyapkina Christina,

Shulepova Irina.

Head: Nikitina Lyubov Ivanovna,

primary school teacher

with. Temkino

1. Introduction. 3

2. The main part. Open the secrets of the autumn leaf. 4

Chapter 1. Our observations.

Chapter 2. Mystery One. Why do leaves change color?

Chapter 3. The second secret. How does leaf fall come?

Chapter 4. Mystery Three. Why do trees shed their leaves?

3. Conclusion. 9

4. List of used literature. 10

5. Applications:

№1. Drawings and photos.

№2. Herbarium.

Number 3. Crafts from dried leaves.

Introduction

Autumn is a great time of the year. A change in leaf color is one of the first signs of autumn. Many bright colors in the autumn forest! Birches, maples turn yellow, patterned leaves of mountain ash, orange and purple leaves of aspens become crimson-red. At this time of the year, it is good to wander through the autumn park, breathe fresh air, observe nature, collect bouquets of fallen leaves, admiring yellow, purple and purple colors.

During the tour, we collected foliage for crafts, and we wondered why the leaves changed color in the fall and why in the summer even a strong wind could not break them, and in the fall they come off themselves? What happened? What secrets does the autumn leaf hide?

The purpose of our study: to find out why autumn changes occur in the life of trees.

To study the causes of leaf color change in autumn;

Learn how leaf fall occurs;

Examine the causes of leaf fall;

To observe the autumn phenomena in the life of trees;

Learn and check folk signs associated with leaf fall.

To find answers to the questions posed, we searched for information in scientific cognitive books, encyclopedias, and reference books on this topic, turned to Internet resources, and made observations.

2. The main part. Open the secrets of the autumn leaf.

Chapter 1. Our observations.

We watched leaf changes in the fall.

In September, yellow leaves appeared on some trees, but the connection with the branches was still strong. Earlier all began to turn yellow leaves on birch and linden. Birches began to turn yellow below.

In October, almost all the leaves changed green to yellow, brown, red, and leaf fall began. The leaves of alder and lilac did not change their color. In rainy weather the leaves seemed paler, in sunny - a little brighter. Unfortunately, we did not succeed in observing how the decrease in temperature affects the brightness of the autumn foliage, since there were no frosts during the falling leaves.

Leaf fall pretty quickly. Maple leaves in front of the school flew over a few days. By the middle of October there were almost no leaves on the trees.

In November, almost all deciduous trees have dropped foliage.

We checked some folk signs associated with leaf fall. Two of them were confirmed.

1. If in the autumn birches turn yellow from the top, the next spring will be early, and if from below, then the later.

Most of the birches, which were observed, began to turn yellow below. Spring

come late. In March, there were severe frosts and unprecedented snowfalls, Spring came only in April.

2. The leaves fall quickly - soon the cold will come and the winter will be harsh, and if the leaves remain green and stay on the trees for a long time - the winter will be short, with slight frosts . This sign was also confirmed: the winter began at the appropriate time, it was frosty and snowy.

Chapter 2. Mystery One. Why do leaves change color?

Forest, just painted tower,
   Purple, Golden, Crimson,
   Fun motley wall
   It is above the light glade

I. Bunin "Falling Leaves"

After studying the literature, we learned why the leaves in the fall change color. Chlorophyll stains them in green color, which is constantly destroyed and restored again by sunlight. In summer, the sun shines a long time, the formation of chlorophyll does not lag behind its destruction. The leaf remains green all the time. Autumn is coming, the nights are lengthening. Light plants get less. Chlorophyll is destroyed during the day, but does not have time to recover. The green color in the leaf decreases, and yellow becomes more noticeable: the leaf turns yellow.

But in the fall, the leaves become not only yellow, but also red, purple, purple. It depends on what coloring matter is in the fading sheet. (Appendices № 1, 2)

Autumn forest is rich in its colors! The brightness of autumn leaves depends on the weather conditions. If autumn is long, rainy - the color of foliage from excess water and lack of light will be dull, expressionless. If the cold nights alternate with clear sunny days, then the colors will match the weather - juicy, bright.

With alder and lilac foliage will fall green regardless of the weather. In their leaves, except for chlorophyll, there are no other coloring matter.

Chapter 3. The second secret. How does leaf fall come?

Leaf, leaf, leaf fall!

Who is to blame?

Maybe the wind is naughty

Play decided with foliage?

S. Rand "Leaf, leaf fall"

Leaf fall is the biological process of plant foliage shedding.

Nobody says to the tree when it is necessary to drop the foliage. But autumn is approaching - and the leaves on the trees change their green color. Nutrients start to be pulled from the leaves to the trunk.

Changes also occur in the leaf stalks. The scape consists of "bricks" (cells) and thin tubes (vessels), along which nutritious juices flow from the tree. They need leaves for growth and development. In the summer, the “bricks” are firmly connected to each other and the sheet is also firmly attached to the branch.

Try to pick a green leaf, for example, from a birch. It is easier to break than to separate without any damage.

And in the fall? The more yellowed or reddened the leaf, the easier it breaks. And there comes a moment when it is only to touch the sheet, as it immediately falls from the branch.

In the fall, the connections between the blocks in the stem are destroyed because chlorophyll grains, which produced building material for the whole tree, were destroyed. Formed a special cork layer. He, like, a partition between the stem and branch. The leaf rests only on thin filaments. Even a slight whiff of wind breaks these fibers. The leaves are falling.

Chapter 4. Mystery Three. Why do trees shed their leaves?

Autumn knocks on our window
Colder every day.
And the trees suddenly undressed
Know them cold uneasy?
Hats and coats removed
The leaves are on the ground.
Why are they on the branches
Leave leaves do not want?

Although our deciduous trees live for dozens, often hundreds of years, the leaves they "work", only one season.

In the green leaf, the entire lower surface is covered with transparent skin and is dotted with small openings — the stomata. Under the influence of ambient temperature and humidity, they open and close. Like window vents in homes. The water that the root sucks up the trunk to the branches and leaves. When the stoma openings are open, moisture evaporates from the leaves, and new portions of water are pulled through the barrel to the crown.

The sun heats the leaf, and evaporation cools it. Trees need a lot of water. During the summer, big birch, for example, evaporates about 7 tons of water. In winter, so much moisture from the soil will not get. Winter for trees is not only cold, but also, most importantly, a dry season. Losing leaves, trees are protected from the "winter drought." Trees have no leaves - there is no such abundant evaporation of water.

In addition, the trees need leaf fall for medicinal purposes. The plant receives from the soil not pure water, but solutions of various salts. These salts, passing with the water through the whole plant, fall into the leaves. Some of them go to feed the plants, and the excess accumulates in the leaves. A large amount of mineral salts disrupts the normal work of the leaves and becomes harmful to the plant.

The third reason for falling leaves: to protect the thin fragile branches of a tree from the severity of snow. So the leaf fall adjusts the trees for winter.

The leaves evaporate the water,
   And in winter there is no water.
   So they won't have enough moisture.
   And do not escape troubles.
   Winter blizzard on the leaves
  It will snow out.
   The tree will not stand:
   Snow can break it.
The leaves also accumulated
  Salt harmful over the summer.
   Drop the tree leaves,
   And get rid of it.

That's why it comes
   In the autumn forest or in the garden
   Golden, rustling, quiet

LISTOPAD!

Conclusion

Summing up the research work, we can conclude that we have achieved our goal. We discovered the secrets of the autumn leaf: we learned that the change in the color of the leaves is due to the lack of sunlight, that in the fall the leaves from the trees fall so easily because the connection between the leaf and the tree branch is destroyed; that trees need leaf fall to survive a dry and snowy winter and get rid of unnecessary substances.

During the study, we collected, studied the leaves of trees, made a herbarium and compositions from this natural material, made sketches and photographs (Appendices). These materials can be used in the lessons of the surrounding world, technology, study circles. We learned to conduct observations, work with various sources of information, select the necessary material, arrange our work.

We want to thank our classmates who worked on the project with us and helped in the design of the work.

Bibliography

1. Graubin G. Why fall - leaf fall? - Moscow, “Kid”, 1987, p. 24

2. Why and why. Encyclopedia for the curious. Ed. Pokidaeva T., Frolova T., - M .: Machaon, 2007, p. 255

3. Pleshakov A. Atlas-determinant. From Earth to Sky - Moscow, "Enlightenment", 2011, p. 222

4. Pleshakov A. The World. Textbook, Grade 2 - Moscow, "Enlightenment", 2012, p. 144

4. Internet resources:

/ 2010/11 / blog-post
   / wiki /