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What is the process of changing the color of leaves in autumn called? Why do leaves change color in autumn? The strongest orange natural dyes

Yellow and red, orange and brown - all leaves have their own shade. Let's see where this color difference comes from.

In summer the leaves are green color because of a large number chlorophyll. This pigment is the breadwinner of the plant, since it is with its help that the plant in the world synthesizes glucose from carbon dioxide and water, and from it all the rest. nutrients. In the presence of light, chlorophyll in a living leaf is constantly destroyed and re-formed.

In addition to chlorophyll, the leaves also contain other dyes - yellow xanthophyll and orange carotene (the same one found in carrots). In summer, these pigments are invisible, as they are masked by a large amount of chlorophyll. In autumn, the vital activity in the leaf fades, and chlorophyll is gradually destroyed. This is where the yellows and oranges come in.

The destruction of chlorophyll is more intense in sunny weather. That is why in cloudy rainy autumn the leaves retain their green color longer. But if the Indian summer comes to replace the precipitation, then the crowns of the trees turn into the usual autumn colors in a couple of days.

In addition to gold, many crimson leaves fall at our feet. They are so because of a pigment called anthocyanin. Unlike chlorophyll, anthocyanin is not associated with intracellular plastic formations (grains), but is dissolved in cell sap.

With a decrease in temperature, as well as in bright light, the concentration of anthocyanin in the cell sap increases. In addition, stopping or delaying the synthesis of nutrients in the foliage also stimulates its synthesis. Thus, the red color of leaf fall simply indicates that the life processes in the leaves stop on the eve of winter.

The brightness of autumn colors depends on what the weather is like. If there is a lot of showers, the foliage from excess water and lack of light will be dull, inexpressive. If cold nights alternate with clear sunny days, then the colors will match the weather - juicy and bright. The leaves on the south side of the tree will also always be more saturated in color, as they receive more sunlight.

What dyes make leaves different colors.

Throughout the year, our planet plays with different colors. And all thanks to the plants for which it is rich. And, probably, many people had such a question: why are the leaves of one color or another? Especially, it interests our children, who are so fond of asking questions. And in order to answer them correctly, you need to properly understand yourself.

What pigment colors leaves green or red?

IN school curriculum Biology class should have a similar topic. Some may have already forgotten, and some just do not know yet. But the pigment that is responsible for the green color of the leaves is chlorophyll. Let's take a closer look at this aspect.

Leaf color green:

  • Chlorophyll is a substance that absorbs sunlight and, with the help of water and carbon dioxide, produces useful organic substances for plants. Or, as they say on scientific language, turns inorganic substances into organic.
  • It is this pigment that is fundamental in the process of photosynthesis. Thanks to him, all living organisms receive oxygen. Yes, this information is known to any student. But few have thought about how chlorophyll turns leaves green.
  • Yes, the element itself is also green. And since it prevails in plants, the color also depends on it. And you can draw a direct relationship between the color of foliage and the amount of chlorophyll.
  • But that is not all. If you delve in more detail into a similar topic, you can find out much more. The fact is that chlorophyll absorbs the spectra of colors such as blue and red. This is the very reason why we see green leaves.

Leaves red:

  • Based on the above reasons, you can find the answer to why the leaves are red. Even if you do not take into account the course of biology. From a logical point of view, the red color also, to some extent, depends on chlorophyll. Or rather, from his absence.
  • The pigment responsible for the red color in the leaf is anthocyanin. Also, this element is responsible for the blue and purple color of leaves, flowers and fruits.


  • Anthocyanin, like chlorophyll, absorbs certain color spectra. In this case, it's green.
  • By the way, there are plants that do not have green leaves or flowers. It depends on the fact that they lack chlorophyll. And in its place is anthocyanin.

How do you explain the change in color of tree leaves in autumn?

What a beautiful autumn we have. Despite the rain and cloudy sky, it is beautiful in its own way. It is autumn that the trees are painted in different colors. Of course, it depends on the weather and the nature of the tree. But everyone paid attention that even on one sheet there can be several shades or colors.

  • Previously, it was believed that all pigments are constantly present in the foliage. And when the amount of chlorophyll decreases, then other colors become visible. But this option is not entirely true. Specifically refers to anthocyanins.
  • This pigment begins to appear in the leaves only after the level of chlorophyll begins to decline.
  • Let's look at this process in more detail. In autumn, the sun is already not so warm, which means that there is less chlorophyll. Since it is he who is responsible for the nutrients in plants, their number is also reduced. So the leaves begin to prepare for the cold.
  • This process is very subtle and thoughtful. All those useful substances that the plant has accumulated over the summer slowly move into the branches and root. There they will be all the cold time. And in the spring they will use this stock so that new green leaves appear.


  • But the coloring of the leaves, in addition to natural processes, is also affected by the weather. Usually in sunny weather, anthocyanins predominate more. If the autumn is cloudy and rainy, then there will be more yellow color trees.
  • But that's not all. The color of the leaves also depends on the breed of the plant itself. Everyone noticed that the maple often has reddish leaves, but the linden and birch always dress in a golden color.
  • Just before winter, when all the coloring pigments are completely destroyed, the leaves become Brown. They no longer have any nutrients left, the leaves dry up and fall off. At this stage, the cell walls of the leaves become visible.

What substance turns foliage yellow: plant pigments

Yellow color is very beautiful in autumn, especially on a clear and warm day. It is not for nothing that autumn is called golden. Almost any plant changes its color, starting with yellow. Yes, some have it single color, and some have it only as an additional one.

  • A specific pigment is responsible for each color. Carotene This pigment gives plants their yellow color. The word is familiar and can often be heard in advertising. Perhaps many did not know its meaning. Or they just didn't even know what it was.
  • This pigment belongs to the group of carotenoids. Found in all leaves and plants. Stays in them all the time. It's just that chlorophyll prevails over carotene, so the leaves are mostly green. And after its collapse, they begin to be painted in other colors.


  • This plant pigment is used as natural dye. It is mined chemically, but exclusively from natural raw materials. It is widely applied in Food Industry and other areas.
  • beta-carotene, which just overshadowed the advertising business, also apply to carotenoids. The fact is that there are about 600 subspecies of them. Almost all yellow, red, orange and even green vegetables and fruits have it. For example, green onion, tomato, pumpkin, persimmon, blueberry, sorrel carrot. The list is very long. It is also very important for the human body.

What substance colors foliage orange: plant pigments

Orange, like yellow, is constantly in the leaves, it's just overshadowed by chlorophyll. Thus, making the plants green. AND Orange color also begins to manifest itself when that same chlorophyll is destroyed.

  • The pigment responsible for the orange color is xanthophyll. It also belongs to the class of carotenoids, like carotene. After all, these colors are on fine line between themselves.
  • I would like to note that carrots color this particular pigment. It contains the most of it. Therefore, it is this pigment that is responsible for the orange color of all fruits and the color.
  • Xanthophylls, like other carotenoids, are essential human body. Other living beings too. Since they cannot synthesize it on their own, but can only get it with food.


  • It is no secret that carrots are rich in vitamin A. Accordingly, all these pigments are the main carriers of this vitamin. More precisely, the predecessors.
  • It is also worth noting that they are antioxidants in our body. Every girl knows about this aspect. After all, it directly depends appearance hair, nails and the body as a whole.

The strongest orange natural dyes

Each housewife faced such a problem in the kitchen when, after, for example, beets, her hands turned red. If you rub carrots a lot, then the same story can happen. It's just that the color is not as saturated, so it's not as noticeable. Also, by picking a certain flower, you can paint your hands in the appropriate color.

  • Natural dyes are widely used in cooking, for dyeing fabrics, in medicine and cosmetology.
  • Coloring pigments are produced by bacteria, corals, fungi, algae and plants. Naturally, the corresponding color. Of course, plants are the most accessible.
  • You can get them yourself, the main thing is to follow the technology. And you also need to know which ingredients are suitable for these purposes.


  • carrot
  • celandine leaves and flowers
  • tangerine and orange zest
  • paprika
  • onion peel
  • pumpkin

As you can see, all products are available and almost all are orange in color. You can also get such a dye by mixing yellow and red.

The leaves of which group of trees turn red in autumn?

Probably, many have noticed that not all trees are red in autumn. But what is the beauty of nature. Especially in combination with yellow and orange flowers. One gets the impression that the forest is shrouded in festive attire. But what kind of trees have exactly a red tint? Let's look at this issue in more detail.

  • This color is not permanent in the leaves, but begins to be produced only after the breakdown of chlorophyll.
  • Usually, those trees that grow on poor, unmineralized soil turn red.
  • An interesting fact is that trees use this color to repel insects and pests.
  • Anthocyanin, the presence of which stains the foliage red, helps to endure frosts and avoid hypothermia.
  • More common in trees such as maple, rowan, bird cherry and aspen

Changing the color of trees is a real miracle of nature, which is so pleasant to watch. Please yourself with pleasant emotions in the fall, because these are unforgettable pleasant sensations.

Video: Why do leaves change color?


"Forest, like a painted tower, purple, gold, crimson"

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

The leaves of plants, along with green chlorophyll, contain other pigments. To verify this, let's do a simple experiment. First of all, let's prepare the extract of chlorophyll, as we described above. Along with chlorophyll, alcohol also contains yellow pigments. To separate them, pour a small amount of alcohol extract (about two milliliters) into a test tube, add two drops of water and about 4 milliliters of gasoline. Water is introduced in order to facilitate the separation of the two liquids. After closing the test tube with a cork or finger, shake it vigorously. Soon you can see that the lower (alcohol) layer turned golden yellow, and the upper (gasoline) - emerald green. The green color of gasoline is due to the fact that chlorophyll dissolves better in gasoline than in alcohol, so when shaken, it usually completely passes into the gasoline layer.

The golden yellow color of the alcohol layer is due to the presence of xanthophyll, a substance insoluble in gasoline. Its formula is C40H56O2. By chemical nature, xanthophyll is close to carotene present in carrot roots - C40H56, therefore 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 do not see it: the intense green color of chlorophyll “clogs” the yellow color of carotene, and we do not distinguish it, as xanthophyll previously in alcohol hood. To see carotene, you need to convert green pigment into a compound insoluble in gasoline. This can be achieved with alkali. In the test tube where the separation of xanthophyll occurred, add a piece of alkali (KOH or NaOH). Close the vial with a cork and shake the contents thoroughly. After the separation of the liquids, it can be seen that the pigment distribution pattern has changed: the lower alcohol layers turned green, and the upper, gasoline, yellow-orange, characteristic of carotene.

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

The autumn forest is painted, however, not only in yellow tones. What is the reason for the purple and crimson color of the leaves? Along with chlorophyll and carotenoids, plant leaves contain pigments called anthocyanins. They are highly 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. This is easy to verify by experience.

First of all, prepare an extract of anthocyanins. For this purpose, the leaves of the euonymus or some other plant, painted in autumn in red or purple tones, chop with scissors, place in a flask, add water and heat on a spirit lamp. Soon the solution will turn reddish-blue due to the presence of anthocyanins. Pour the resulting extract of pigments into two test tubes. Add weak hydrochloric or acetic acid to one, and ammonia solution to the other. Under the action of an acid, the solution will turn pink, while in the presence of an alkali, depending on the amount and concentration of this alkali, it will turn 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. Researchers have found that the formation of anthocyanins is promoted by high content Sugars in plant tissues, relatively low temperature and intense lighting.

The increase in sugar content in autumn leaves occurs due to the hydrolysis of starch. This is essential for transporting valuable nutrients from dying leaves to the interior of plants. After all, starch itself is not transportable in the plant. However, the rate of outflow of sugars formed as a result of its hydrolysis from the leaves at low temperatures small. In addition, when the temperature drops, the respiration of plants is weakened and, consequently, only a small amount of sugars undergoes 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.

Other facts also testify to the conversion of excess sugars into anthocyanins. If in a vine by ringing (removing part of the bark in the form of a ring) to impede the outflow of photosynthesis products, then the leaves located above the ring become red in two to three weeks due to the accumulation of anthocyanins. At the same time, so many of them are formed 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 Bottom part leaves, as well as 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 a phosphoric acid residue, the sugar molecule remains inactive. Therefore, in plant tissues there is an accumulation of excess amounts of sugars, which are used for the synthesis of anthocyanins. An increase in the content of these substances leads to blue stems and leaves of plants experiencing a lack of phosphorus.

The formation of anthocyanins also depends on the intensity of light. If you look closely at the bright color of trees and shrubs in autumn, you will notice that the crimson color is mainly those leaves that are best lit. Move the euonymus bush blazing with fiery colors, and you will see yellow, pale yellow and even green leaves inside. During a rainy and cloudy autumn, the foliage lasts longer on the trees, but it is not as bright due to the lack of sun. Yellow tones predominate, due to the presence of carotenoids, and not anthocyanins. Low temperature also promotes the formation of anthocyanins. If the weather is warm, then the forest changes its color slowly, but as soon as the frost hits, the aspens and maples immediately blaze. MM. Prishvin wrote in the miniature “Lamps of Autumn”: “Lamps of autumn lit up in the dark forests, a different leaf on dark background it burns so brightly that it hurts to look at. The linden is already all black, but one bright leaf of it remains, hangs like a lantern on an invisible thread and shines.

flora rainbow

Since we are talking about plant pigments, we should also talk about the reasons for the diversity of flower colors. Why do flowers need their bright, juicy color? 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 which insects the color signals are intended for. The fact is that in relation to color, insects are quite capricious. Let's say bees, bumblebees, wasps prefer pink, purple and blue flowers, and flies usually huddle around yellow ones. Red is the color of many insects, endowed with not very perfect vision, confused with dark gray. Therefore, in our latitudes, pure red flowers are quite rare. The exception is poppy, but its petals also have an admixture of yellow; usually it is this shade that the bees notice. Butterflies distinguish red better than other insects - they, as a rule, pollinate the red flowers of our latitudes, for example, carnations. But among tropical plants, red is more common, and this is partly due to the fact that their flowers are pollinated not by insects, but by birds: hummingbirds or sunbirds, whose eyesight 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 lungwort plant: pink color its young flowers change to blue as it ages. The bees no longer visit the old flowers of the lungwort: they, as a rule, are pollinated and do not contain nectar. And in this case, the color change serves as a signal for insects - do not waste time! But in Gilia (USA) - a beautiful plant from the cyanotic family, a relative 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 hylia changes the color of the newly appearing 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 found only in flowers are as beautiful as the color they give: escholxanthin, petaloxanthin, gazaniaxanthin, auroxanthin, chrysanthemaxanthin, rubichrome.

Along with carotenoids, anthocyanins also determine the color of flowers. The shades of these pigments are very diverse - from pink to black-violet. Despite such a variety of colors, all anthocyanins are arranged according to the same type - they are glycosides, that is, sugar compounds with a non-carbohydrate part, the so-called aglycone. An example is the coloring matter contained in cornflower flowers - anthocyanin. Its aglycone - cyanidin - is one of the most common, formed as a result of the cleavage of two glucose molecules from an anthocyanin.

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

We have already said that the same lungwort plant can have flowers of different colors: pink - young and blue - old. The bluing of the 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, has an acidic reaction, 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 occur 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 point of view, take a bright red petal of some plant, such as a geranium, a rose, and crush it between your fingers. In this case, the contents of the cytoplasm and vacuole will also mix, as a result, the petal at the site of damage will turn blue. However, it would be wrong to associate the color of anthocyanins only with their indicator properties. Research recent years showed that it is also determined by some other factors. The color of anthocyanin pigments can change, for example, depending on which ions they are complexed with. When interacting with potassium ions, the complex acquires a purple color, and with calcium or magnesium ions - blue. If you cut off a flowering bluebell and place it in a solution containing aluminum ions, the petals will turn blue. The same is observed if we combine solutions of anthocyanin and aluminum salts.

Many readers may be familiar with the novel The Black Tulip by Alexandre Dumas, which tells in an action-packed form about the breeding of an unusual black tulip variety. Here is how the author of the novel describes it: “The tulip was beautiful, wonderful, magnificent; its stem is eighteen inches high. It stretched slenderly upwards between four green, smooth, even, like an arrow, leaves. Its flower was completely black and shone like amber. For almost five centuries, the failures of gardeners who tried to bring out the black tulip pursued. 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 successive crossing of two varieties - “Queen of the Night” and “Viennese Waltz”. Six Dutch research centers took part in the work. The resulting flower is ideal in its classic size.

Gardeners also strive to create black roses. Such varieties have been bred that, in dim lighting, really appear black (in fact, they are dark red). Wild black roses grow in the Hawaiian Islands. In honor of Goethe's immortal work Faust, gardeners have created a variety of black pansies called Doctor Faust. Pansies, as you know, were the favorite flowers of 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, petals can be colored by other substances, including flavones and flavonols. And what pigment paints cherry orchards in a milky color, turns bird cherry bushes into snow-white snowdrifts? It turns out that there are no white pigments in their petals. The white color gives them. air. If we look at the petal of a bird cherry or any other white flower under a microscope, we can see many transparent and colorless cells separated by vast empty spaces. It is thanks to these air-filled intercellular spaces that the petals strongly reflect light and therefore appear white. And if you crush such a petal between your fingers, then a transparent spot will appear at the place of compression: here the air will be forced out of the intercellular spaces.

And yet in nature there is White paint, for example, she is painted in elegant White color the bark of our beloved birch. This coloring matter is called - betulin, from the Latin name of birch - Betula. Those who believe that birch is the only plant with white bark are mistaken. This is wrong. In Australia, the flooded eucalyptus grows. It is so named because it grows in the beds of drying 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, effectively standing out against the background of the surrounding green thickets.

The three-coniferous Bunge pine also white bark. This rare view, found in nature mainly in the mountains of Central China. The plant is bred throughout the country near palaces and temples. White-trunked 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 from all over the world. More than 30 years ago, the famous Indian scientist T.R. Seshadri, who studied natural dyes a lot, wrote: “The music of colors is more complex and changeable in nature than the music of sounds. It is even possible that in reality it is even more refined than we think.

Green animals - reality or fantasy!

In the works of the fantastic genre, one can often read about green humanoid creatures. The green color of these organisms, due to chlorophyll, allows them to independently synthesize organic substances from inorganic ones at the expense of light energy. Is this possible in nature? First of all, it should be noted that there are animals on Earth that eat in a similar way. For example, the green euglena, well known to all biologists, is often found in stagnant puddles. Botanists consider euglena an algae, and zoologists still traditionally classify it as an animal. What's the matter?

Euglena moves freely in the water with the help of a flagellum. This method of movement is characteristic both for a number of protozoa and for some botanical objects, such as zoospores. certain types algae. Euglena contains chlorophyll, therefore, with its intensive reproduction, the water in the puddles acquires an emerald green color. 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, then it loses its green color and, like animals, begins to feed on ready-made organic substances. Euglena still cannot be called a typical animal, so we will look for other representatives. feeding, like plants, with the help of chlorophyll.

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

Attempts to free mollusks from chloroplasts by placing them in the dark for a month and a half were unsuccessful, as well as removing them from eggs. Chloroplast-free mollusk larvae died at an early stage of development. Inside an animal cell, chloroplasts are densely packed and occupy a significant volume. Thanks to them, mollusks that do not have a shell turn out to be painted in an intense green color.

Why did siphon algae "fall in love" with mollusks? The thing is. that, unlike other green algae, they do not have a cellular structure. Their large, often bizarre body is one giant "cell". The word "cell" I put in quotation marks is not accidental. Although there are no cell walls in the body of siphon algae, one can hardly call them unicellular organisms; 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 were called siphon. Absence 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 an alga contains one or more chloroplasts. If there are many of them, they are disc-shaped or spindle-shaped. Single ones have a mesh structure. Scientists believe that the mesh structure is created as a result of the connection of small chloroplasts with each other.

Many scientists have observed the assimilation of carbon dioxide by chloroplasts in animal cells. In freshly harvested mollusks, green elision, the intensity of photosynthetic carbon dioxide assimilation was 55–67% of the value determined for the intact alga Codium brittle, from which the chloroplasts were “acquired” by the mollusks. It is curious that the content of chlorophyll per 1 gram of fresh tissue mass in algae and 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 was 20–40% of the initial one.

In 1971, scientists observed the release of oxygen during the photosynthesis of chloroplasts found in tridacna cells. Tridacna are typical inhabitants of tropical seas. They are especially widespread on the coral reefs of the Indian and Pacific Oceans. The giant among the mollusks looks like a giant tridacna, sometimes reaching a length of 1.4 meters and a total weight of 200 kilograms. Tridacna are interesting for us because of their symbiosis with unicellular algae. Usually they are located at the bottom so that their translucent mantle, protruding between the shell valves, is turned upwards and is strongly illuminated by the sun. In its intercellular space, green algae settle in large numbers. Despite its considerable size, the mollusk feeds only on those substances that are produced by symbiont algae.

In the Mediterranean Sea and off the coast of France in the Atlantic, a convolute worm is found, in which green algae also live under the skin, synthesizing organic substances from inorganic ones. Due to the activity of its “tenants”, the worm does not need additional sources of food, so its gastrointestinal tract has atrophied. At low tide, many convolutes leave their burrows to sunbathe. At this time, the algae under their skin photosynthesize intensely. Some species of these worms are completely dependent on their settlers. So, if the young worm does not “infect” with algae, then it will die of hunger. In turn, the algae that settled in the body of the convolute lose the ability to exist outside of its body. “Infection” occurs with the help of “fresh” algae that have not yet lived in symbiosis with worms at the moment when the larvae of the worm come out of the eggs. These algae are most likely attracted by some substance secreted by the eggs of the worms.

In connection with the consideration of the issue of the functioning of chloroplasts in animal cells, the experiments of the American biochemist M. Nass are of extremely great interest, in which it was shown that the chloroplasts of the siphon algae Caulerpa, Chara algae Nitella, spinach and African violet are captured by connective tissue cells (the so-called fibroblasts) of mice . Usually in fibroblasts that have swallowed foreign body(Scientists call this process phagocytosis), a vacuole is formed around the absorbed particle. Gradually, the foreign body is digested and absorbed - disappears. When chloroplasts were introduced into the cells, vacuoles did not appear, and fibroblasts did not even try to digest them.

Plastids retained their structure and ability to photosynthesize for three weeks. The cells that turned green due to their presence were dividing normally. At the same time, chloroplasts were spontaneously distributed among daughter cells. Plastids, which were in fibroblasts for about two days, and then again isolated, remained intact. They assimilated carbon dioxide at the same rate as they photosynthesized fresh chloroplasts isolated from plants.

Suppose that in the course of evolution such beings arise or are found on other planets. What should they be? Scientists believe that in such an animal, chlorophyll will be concentrated in the skin, where light freely penetrates, which is necessary both for the synthesis of green pigment and for the formation of organic substances. The “Green Man” must do something the opposite: during the day, like a fairy-tale king, walk in clothes invisible to everyone, and at night, on the contrary, dress to keep warm.

The problem is whether such an organism can get enough food through photosynthesis. Based on the maximum possible intensity of plant photosynthesis in the most favorable conditions of existence, it is possible to 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 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. This mass will concentrate about 153 calories of energy. This amount is clearly not enough to meet the energy needs of the human body, which are 2000-4000 calories per day.

Let's take into account that the "green man" does not need to think about food and be too active, since food itself enters his body from the chloroplasts of the skin. It is easy to conclude that the absence physical activity and a sedentary lifestyle will make it look like an ordinary plant. In other words, the "green man" will be very difficult to distinguish from prickly pear.

Researchers' calculations show that in order to form a sufficient amount of organic matter, the "green man" in the course of evolution must increase the surface of his skin by 20 times. This can happen due to an increase in the number of folds and processes. To do this, he will need to acquire a semblance of leaves. If this happens, then it will become completely 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 Earth's biosphere, there must necessarily be plant-like organisms that provide food and energy for both themselves and animals. In the second half of the 19th century, it was found that the energy sunlight digested and transformed by the green pigment chlorophyll.

Based on the experiments, we can say 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 regarding the exceptional importance of the red rays of the solar spectrum for photosynthesis. It turned out that the coefficient of use 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 the universe and the creation of life.

As you know, plants absorb carbon dioxide, which is attached to a five-carbon substance called ribulose diphosphate, where it then further participates in many other reactions. The study of the features 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 most of modern plant fauna on the surface of the earth.



Why do leaves change color in autumn? Why does autumn happen different color? The leaves of plants are colored green because they contain chlorophyll, a pigment that is present in plant cells. A pigment is any substance that absorbs visible light. Chlorophyll absorbs sunlight and uses its energy to synthesize nutrients. In autumn, the leaves of plants lose their bright green color. For example, poplar leaves turn golden, while maple leaves seem to flash red. Some chemical transformations begin in the leaves, that is, something happens to chlorophyll. With the advent of autumn, plants prepare for winter. Nutrients slowly move from the leaves to the branches, trunk, root and are stored there during the severe cold. As spring arrives, plants use their stored energy to grow new green leaves. When the energy of the stored nutrients is exhausted, the synthesis of chlorophyll stops. The chlorophyll remaining in the leaves partially decomposes, and pigments of a different color are formed. Yellow and orange pigments appear in the leaves of some plants. These pigments consist mostly of carotenes, the substances that color carrots orange. For example, the leaves of birch and hazel become bright yellow as chlorophyll decays, the leaves of some other trees acquire various shades of red. The red, dark cherry and purple hues of some leaves are due to the formation of anthocyanin pigment. This pigment colors radish, red cabbage, rose and geranium. Under the influence of autumn cold, the leaves begin to chemical reactions that convert chlorophyll to red-yellow compounds. Unlike carotenes and other yellow pigments, anthocyanin is generally absent from green leaves. It is formed in them only under the influence of cold. Color autumn leaves, like human hair color, is genetically determined in each plant species. But whether this color will be dull or bright depends on the weather. The brightest, juiciest colors of the leaves occur in autumn, when the weather is cold, dry and sunny for a long time (at temperatures from 0 to 7 degrees Celsius, the formation of anthocyanin is enhanced). The beautiful coloring of the leaves in autumn happens in places like Vermont. But, for example, in the UK, where the climate is rainy and the weather is overcast almost all the time, autumn leaves are most often dull yellow or brown. Autumn passes, winter comes. Together with the leaves, the plants lose their colorful colors. The leaves are attached to the branches with special cuttings. With the onset of winter cold, the connection between the cells that make up the cuttings breaks up. After that, the leaves remain connected with the branch only by thin vessels, through which water and nutrients enter the leaves. A light puff of wind or a drop of rain can break this ephemeral connection, and the leaves will fall to the ground, adding another touch of color to the multicolored thick carpet of fallen leaves. Plants store food for the winter, like chipmunks and squirrels, but they accumulate it not in the ground, but in branches, trunks and roots. Leaves, into which water stops flowing, dry up, fall from trees and, picked up by the wind, circle in the air for a long time until they settle down on forest paths, lining them with a crisp path. The yellow or red coloration of the leaves may persist for several weeks after they have fallen off. But over time, the corresponding pigments are destroyed. The only thing that remains is tannin (yes, yes, it is he who colors the tea).

Regional competition research work And creative projects

preschoolers and junior schoolchildren"I am an explorer!"

Municipal budgetary educational institution

"Average comprehensive school"No. 18"

Engels municipal district

Saratov region

Individual project on the topic of:

"Why leaves

change color in autumn?

Vorfolomeeva Daria

1st grade student

project Manager

Eterevskaya Ludmila

Vladimirovna

teacher primary school

MBOU "Secondary School No. 18" EMR

Saratov region

Saratov, 2015

    Description of the project…………………………………………………………………. With. 3 - 5

    Introduction……………………………………………………………………… p. 3

    Stages of the project and expected results…………………………………... p. 4 - 5

Stage 1: choice of research method, research progress……………… …… p. 4

Stage 2: study of the literature on this topic, expected results ... p. 4

Stage 3: generalization and systematization of information……………………………p. 4-5

Stage 4: choosing a product of project activities…………………………… p. 5

    Conclusions (meaning of the project for use in practice)…………… … p. 5

    Reflection of project activity…………………………………………….p. 5

    Informational - methodological support…………………………………… With. 6

    Applications:………………………………………………………………………. With. 7 - 9

Why do leaves change color in autumn

Project Description

Here is a maple leaf on a branch.

It looks like new now!

All ruddy, golden.

Where are you, leaf? Wait!

V.D. Berestov

Introduction

Autumn is a wonderful time of the year. Leaf color change is one of the first signs of autumn. Lots of bright colors in the autumn forest! Birches, maples turn yellow, patterned rowan leaves turn crimson-red, aspen leaves turn orange and crimson. At this time of the year, together with my mother, I like to walk in the autumn park or forest, breathe fresh air, observe nature, collect bouquets from fallen leaves, admiring yellow, crimson, purple colors.

One autumn day, I was collecting beautiful leaves for technology lessons. Looking at them, I wondered: why did the leaves change color? Why did the color change from green to yellow and red? Why do trees need leaves at all?

I suggested that the leaves change color from a lack of light or a cold snap.

To answer these questions, I will do some research.

Target: find scientific evidence for the causes of leaf color changes.

Tasks:

    study specialized literature;

    find out what value the leaf plays for the tree;

    study the cause of the change in leaf color;

    answer the question: why do some leaves turn red, while others turn yellow;

    development and design of an information booklet on the topic of the project

Project type:

by completeness: interdisciplinary

by the number of participants: individual

Project milestones and expected results

Stage 1 - organizational . The main method of this stage is the observation of changes in nature. Systematic observation of the change in the color of the leaves on the trees led to the conclusion that the color of the leaves changes in different trees differently.

Observation results V application 1.

I also used the method of interviewing classmates. I found out - do they know why the leaves change color in autumn? Results in Appendix 2.

Stage 2 - theoretical . The main method is the study of literature and the search for information on the Internet.

Having studied the article in the encyclopedia for kids “A miracle is everywhere. The World of Animals and Plants” by T. D. Nuzhdina, and after reading articles with my mother on the Internet, I realized:

    what role does the leaf play in the life of the tree;

    recognized the parts of the sheet;

    discovered the reason for the change in color of leaves in autumn;

    found a lot of interesting additional information on this topic.

Stage 3 - practical. The main method is working with information.

Interest in this topic arose during walks on autumn forest. As a result of observations and study of literature, I learned new concepts and facts:

    The leaves work all summer long: they feed the tree, get it food from the air with the help of sunlight, protect it from sunburn branches and trunk. The leaves that fell in autumn and remained under the trees will not be wasted. They will conserve moisture and protect the roots from frost. Then they will decay, fertilize the earth and feed the tree.

During my research, I found Interesting Facts about changing the color of the leaves; picked up folk omens, proverbs, found the author's fairy tale about leaves, took photographs autumn trees, made crafts from fallen leaves for technology lessons.

The information I received formed the basis of the speech, presentation and information booklet for classmates.

Stage 4 - final . The main method is the analysis of the results of the work performed.

At the beginning of the project, I suggested that the leaves change color from lack of light or cold weather. My assumptions were not confirmed.

I found out that in the fall, as the activity of the leaf fades, the formation of chlorophyll in it slows down, and then completely stops; the destruction of chlorophyll under the influence of sunlight continues. As a result, the leaf loses its green color and yellow-red pigments appear.

I found scientific evidence of the causes of leaf color changes, that is, my goal was achieved.

conclusions

Working on this project gave me the opportunity to read interesting material about nature, I acquired new knowledge - I learned what chlorophyll is and what it is for, trained my powers of observation, learned to work independently, tried my hand at working on a computer and creative work with dry leaves. I applied the acquired knowledge in the lessons of the world and technology. I spoke to my classmates and presented the results of my work.

Reflection

While working on the project, I learned how to work with various sources information, evaluate the quality of my work, which I consider good, work in collaboration with my mother and teacher, draw conclusions based on the data received. Also, working on the project helped develop my personal interest in the study of nature and natural phenomena.

I think that I have achieved my goal.

Information and methodological support:

    T.D. Nuzhdina Encyclopedia for kids “Miracle is everywhere. World of Animals and Plants, Yaroslavl Academy Holding 2003

Annex 1

The results of observing the change in foliage color

Appendix 2

Classmates survey results

Annex 3

Fairy tale

Why do leaves change color in autumn?

Autumn has come. The leaves on the trees began to turn yellow and fall.

Once Marinka was sitting under an oak tree, looking at the yellowed leaves and thinking:

The leaves turn yellow from the cold. They tremble, shrink, and the wind will fly - and the leaves fell off the branches, flew away. Only on the oak the leaves still remained, but even on it there were less and less of them every day.

Once Marinka - a kind soul - could not stand it: she took glue and threads at home and ran to her beloved old oak. She began to tie the last leaves to the branches and glue them so that the wind would not break them off. Maybe the girl tied and glued 20 leaves, or maybe all 30. And she would have saved it, but her hands were completely frozen. Marinka sat down, pressed her hands to her mouth, breathing into her fists: first one, then the other. Then the wind came up again - and suddenly it seemed to Marinka that the leaves above her head were whispering, rustling. Then the oak seemed to stretch with a creak, yawn, and say softly:

Wh-what are you doing here, silly-sh-sh? Why are you disturbing my sleep?

I didn't want to wake you up, - Marinka was embarrassed. - I'll glue the leaves for you, or even oversleep the last ones.

Eh, baby sh! I've finished my chores, it's time to relax. Look what acorns I have grown, beauty! Perhaps new oak trees will grow. But this is later, and now - the days are getting shorter, there is less and less light, which means it's time for the trees to sleep. In the leaves, tiny green grains, living plants, disappeared, dissolved, like sugar in water. There were no green grains, and the leaves turned yellow.

But why yellow and not white or transparent? Marina was surprised.

Because in addition to green grains in the leaves there are also others - yellow ones. While the green grains were working in the leaves, the yellow ones were not visible, but the green grains dissolved and only the yellow ones remained. Here the leaves turned yellow. And then they dry up and fall.

But how is it? ! - the girl got excited. - What will you do without these plants, without leaves? Who will feed you all winter?

But I don’t want to eat or drink, - the oak whispered and yawned with a long yawn. - Makes me sleepy. In winter, sleep like that - grace. In winter, we, the trees, do not grow, do not bloom. Oak sighed and fell silent.

Hey! - Marinka tapped softly on the wrinkled bark. -

I want to ask: maybe it would be better if the leaves remained? Although they are dry, yellow, the tree is much more beautiful with them.

No, - the oak yawned. - In winter, we are not up to beauty. We trees shed their own leaves. If all the leaves are left, in winter such snowdrifts will grow on the branches that they will not withstand, they will break from the weight.

And I thought that the wind breaks the leaves.

It is possible without wind, - the oak whispered. - We build a specially thin partition between the petiole of the leaf and the branch, which does not let juices or water through. A partition grows and separates the leaf from the branch. As soon as the leaf has nothing to hold on to, it will come off and fly. Leaves will fall to the ground and the roots will cover from frost ... Eh-heh-heh ...

The girl wanted to ask the oak for more about bark, about buds, about acorns, but then the wind blew again, and it seemed to her that the old tree was snoring softly.