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12. Pair work. Ask and answer 6 questions to Text 1. ^ Retell one of the texts. Text 2 Pollination The transfer of pollen from the anthers to the stigma is called pollination. Cross-pollinating – when the pollen grains are carried away on the bodies of insects or simply blown by the wind and may land on the stigma of another flower. In self-pollinating plants the pollen comes from the same flower or another flower of the same plant. Wind-pollinated flowers are adapted to their method of pollination by producing the large quantities of light pollen. They have anthers and stigmas which project outside the flowers. Some grasses have anthers which are not rigidly attached to the filaments and can be shaken by the wind. The stigmas of grasses are feathery and act as a net which traps passing pollen grains. Grasses, cereals and many trees are pollinated not by insects, but by wind curents. The flowers are often quite small with inconspicuous leaf-like bracts, rather then petals. They produce no nectar. The anthers and stigma are not enclosed by the bracts but are exposed to the air. The pollen grains, being light and smooth may be carried long distances by the wind and some of them will be trapped on the stigmas of other flowers. Insect-pollonated flowers are considered to be adapted in various ways to their method of pollination. In the course of evolution the structure and physiology of a flower have been modified in ways which improve the chances of successful pollination by insects. Most insect-pollinating flowers have brightly colored petals and scent, which attract a variety of insects. Some flowers produce nectar. Text 3 ^ If other plants can thrive on gases in the air plus water from the soil, why do Venus Flytraps eat insects? Flytraps actually get a good deal of their sustenance like other plants do, through the process of photosynthesis. During photosynthesis, plants use the energy of the sun to drive a reaction that converts carbon dioxide and water to sugar and oxygen. The sugar produced is then converted to energy in the form of ATP, through the same processes used by our bodies to process carbohydrates. However in addition to synthesizing glucose, plants also need to make amino acids, vitamins and other cellular components to survive. To accomplish this, plants needs additional nutrients like: nitrogen - to make amino acids, nucleic acids, proteins ; phosphorus - as part of the energy-carrying ATP molecule; magnesium - as a co-factor that helps many enzymes function; sulfur - to make some amino acids ; calcium - as an enzyme co-factor and to make plant cell walls ; potassium - to regulate water movement in and out of the plant. In the bogs favored by Venus Flytraps, the soil is acidic, and minerals and other nutrients are scarce. Most plants can't survive in this environment because they cannot make enough of the building blocks necessary for growth. The Venus Flytrap has evolved the ability to thrive in this unique ecological niche by finding an alternate means of getting key nutrients like nitrogen. Living creatures like insects provide a good source of the nutrients missing from the soil, and they also contain additional energy-laden carbohydrates. Carnivorous plants have to be able to: attract insects capture bugs discriminate between food and non-food digest their prey All of these steps are accomplished through simple mechanical and chemical processes.In the case of the Venus Flytrap, the leaves forming the trap secrete a sweet nectar that draws in insects searching for food. When an insect lands or crawls on the trap, it is likely to run into one of six, short, stiff hairs on the trap's surface. These are called trigger hairs, and they serve as a primitive motion detector for the plant. If two of these hairs are brushed in close succession, or one hair is touched twice, the leaves close down upon the offending insect within half a second. Inanimate objects like stones, twigs and leaves that fall into the trap, or objects that are placed there , will not move around and fire the trigger hairs. If there is no further stimulation of the hair, the trap stays in its partially shut state until tension can be re-established in the leaves of the trap. This process takes about 12 hours, at which point the leaves spread apart again. The unwanted object either falls out as the leaves re-open or is blown out by the wind. Once the trap fully closes, the leaves form an airtight seal so that: digestive fluids and insect parts are kept inside the trap bacteria and molds can't get in . To make sure that the insects are contained within the trap, the edges of the leaves have finger-like cilia that lace together when the leaves press shut. These long, hair-like projections make the plant look like it has spiny teeth; but the cilia are really only used to latch the trap shut. Once the insect is firmly ensconced in the trap, the process of digestion can begin. The trap secretes acidic digestive juices that: Dissolve the soft tissues and cell membranes of the food. Serve as an antiseptic to kill small amounts of bacteria inadvertently eaten or sealed in with the food . Enzymatically digest DNA, amino acids and other cellular molecules into small pieces that can be taken up by the plant . These digestive juices are secreted from glands on the inside surface of the trap, right onto the trapped prey. The insect is bathed in these juices over a period of five to 12 days, during which the insect is digested and nutrients are extracted.. The process continues until all that's left of the insect is its hard exoskeleton. Once the nutrients are depleted from the acidic bath, the plant reabsorbs the digestive fluid. This serves as a signal to reopen the trap, and the remains of the insect are usually either washed away in the rain or blown away by the wind. ^ Text 4 Странные хищники Растения-хищники представлены практически во всех экосистемах – от Арктики до тропиков. Особенно много их на юго-западе Австралии. Некоторые распространены довольно широко, в то время как ареал других ограничен. Венерина мухоловка, например, растет лишь в Северной и Южной Каролине. Особенно многочисленны "хищники" во влажной местности - на болотах и топях – здесь они испытывают постоянный дефицит минеральных веществ, в первую очередь, азота. Восполнить его удается благодаря способности ловить живую добычу. Впрочем, и традиционный для растений способ питания – фотосинтез – они также используют. Большинство насекомоядных растений – многолетники с прикорневой розеткой листьев, преобразованных в ловушки. Различают три вида ловушек: липкие, захлопывающиеся и ловушки-сосуды. При этом любая из них - это всегда только видоизмененные листья или их отдельные части, а не цветки, как может показаться на первый взгляд. Для привлечения насекомых у "хищников" существует множество средств: яркая окраска листьев, пьянящий аромат, сладкий нектар и другие. Оказавшись в ловушке-сосуде, насекомые тонут в жидкости, которая ее наполняет, или разлагаются под действием пищеварительных соков, попав на "липучку". Далее растения выделяют кислоту, разрушающую покровы жертвы, и пищеварительные ферменты, разлагающие ткани на более простые элементы. Всасывание питательных веществ происходит через клеточные стенки ловушек. В Тропической Азии, на Сейшельских островах, на Мадагаскаре, и в Северной Австралии обитают самые мощные из всех "хищников" – представители рода Непентес (Nepenthes). Они могут расти и в горах - на высоте до 2000 м, и на краю леса, и даже в зоне морского прибоя. Эта лиана чаще всего селится на стволах деревьев, обвивая их на десятки метров в высоту и вынося узкие соцветия к свету. Лист непентеса состоит из трех частей. В основании – широкая пластинка, поддерживающая фотосинтез. Средняя часть наделена чувствительностью, дающей возможность растению обвивать листья деревьев. И, наконец, верхушечная – кувшинчик с крышечкой – для ловли насекомых. Кувшинчики окрашены в яркие цвета: красные, молочно-белые и расцвечены пятнистым рисунком. Иногда в них попадает крупная добыча: грызуны, жабы и даже птицы. Однако основным источником питания все же остаются насекомые. Над устьем расположена неподвижная крышка, защищающая содержимое кувшина от дождевой воды и служащая посадочной площадкой для насекомых. Добыча, привлекаемая цветом, запахом и нектаром, соскальзывает в кувшин, так как его внутренняя поверхность очень скользкая. Здесь не удерживаются даже насекомые, способные передвигаться по вертикальному стеклу. Попадая в жидкость, содержащую ферменты и кислоты, и в течение 5-8 часов добыча полностью переваривается. Остается только хитиновый покров. Впрочем, непентес может выделять фермент, способный растворить даже хитин.
^ appearance habitat feeding habits way of reproduction. 16.Choose any of the following ideas ( or propose your own), find information and write an essay ( 150-250 words). Plants: Humans` best friends Plants: Humans` enemies Examples of adaptation among Plants Plants and Global Warming. Unit 10
Words
Make sure you know these words
Working with words ^
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^ Cap, ring, volva, gills, mycelium, stem, spores, hypha. ![]() 4.Choose the correct word to complete the sentences.
Unlike green plants, which use ........................... and light as sources of carbon and energy, respectively, fungi meet these two requirements by assimilating preformed organic matter; carbohydrates are the preferred nutrient ...................... Fungi can readily ....................... and metabolize a variety of soluble carbohydrates, such as glucose, xylose, sucrose, and fructose, but are also characteristically well equipped to use ..................... carbohydrates like starches, cellulose, ........................., and lignin. To do so, they must first digest these polymers .......................... Saprobic fungi ................................. their food from dead organic material; parasitic fungi do so by feeding on living organisms (usually plants), thus causing ........................... Working with word combinations and sentences ^ Составлять отдельное царство, общие характеристики, вегетативный рост, многочисленные грибы, широкое применение, хлебная плесень, разветвленные волокна, жесткие стенка клетки, размножаться почкованием, замедлять рост, неизбежное загрязнение, чашки петри подлежащие уничтожению, загадочное заболевание, потребление ржаного хлеба, уничтожить болезнь, зерно ржи, ядовитые органические соединения, собирать зерно, пасти скот, выпускать споры, сокращение урожайности, контролировать кровотечение, батон дрожжевого хлеба, кисть винограда, фундаментальные знания, пивные дрожжи, заложить основу. ^
^ contamination taxonomic kingdom alkaloid brewer mutant fetus hemorrhage Working with texts 8. Read and translate the text. Text 1 Fungus A plural fungi, any of about 50,000 species of organisms of the kingdom Fungi, or Mycota—including yeasts, rusts, smuts, mildews, molds, and mushrooms. They are among the most widely distributed organisms on Earth and are of great importance. Many fungi are free-living in soil or water; others form parasitic or symbiotic relationships with plants or animals, respectively. Historically, the fungi were included in the plant kingdom, but because they lack chlorophyll and the organized plant structure of stems, roots, and leaves, they are now considered to constitute a separate kingdom. Fungi are eukaryotic organisms having two common characteristics: anatomically, their principal mode of vegetative growth is through mycelium; physiologically, their nutrition is based on absorption of organic matter. They are the culmination of a major direction in evolution distinctly different from that of plants or animals, an evolutionary line established by organisms whose nutrition was based on absorption of organic matter. The mushrooms, by no means the most numerous or economically significant of the fungi, are the most conspicuous members of the group; thus, the Latin word for mushroom, fungus (plural fungi), has come to stand for the whole group. Similarly, the study of fungi is known as mycology. Fungi other than mushrooms are sometimes collectively called molds, although this term is better restricted to fungi of the sort represented by bread mold. B A typical fungus consists of a mass of branched, tubular filaments enclosed by a rigid cell wall. The filaments, called hyphae (singular hypha), branch repeatedly into a complicated, radially-expanding network called the mycelium, which makes up the thallus, or undifferentiated body, of the typical fungus. Some fungi, notably the yeasts, do not form a mycelium but grow as individual cells that multiply by budding or, in certain species, by fission. The mycelium grows by utilizing nutrients from the environment and, upon reaching a certain stage of maturity, forms—either directly or in special fruiting bodies—reproductive cells called spores. The spores are released and dispersed by a wide variety of passive or active mechanisms; upon reaching a suitable substrate, the spores germinate and develop hyphae that grow, branch repeatedly, and become the mycelium of the new individual. Fungal growth is mainly confined to the tips of the hyphae. C In 1928 a green mold accidentally grew in a culture dish of Staphylococcus bacteria that the bacteriologist Alexander Fleming was studying in a London hospital. The fungus colony that developed inhibited the growth of the bacteria. Such unavoidable contamination certainly had occurred many times before in laboratories throughout the world, but the people who may have seen such cultures probably regarded them as contaminated plates to be discarded as soon as possible. Fleming, however, carefully recorded his observation and in 1929 published a scientific report announcing the discovery of penicillin, the first of a series of antibiotics—many of them derived from fungi—that have revolutionized medical practice. D In 1951 a strange disease broke out in the small French village of Pont-Saint-Esprit, and several persons died. Doctors were baffled by the mysterious malady until it was recognized as a form of “St.Anthony's fire”—ergotism—that had resulted from eating bread made from contaminated flour. Ergotism was prevalent in northern Europe in the Middle Ages, particularly in regions of high rye-bread consumption; modern grain-cleaning and milling methods have practically eliminated the disease. The cause of ergotism is ergot—a fungus. More precisely, ergot is a sclerotium (plural sclerotia), a special part of a fungus that develops on grasses and especially on rye. The wind carries the fungal spores to the flowers of the rye, where the spores germinate, infect and destroy the ovaries of the plant, and replace them with masses of microscopic threads cemented together into a hard fungal structure shaped like a rye kernel but considerably larger and darker. This is ergot, and it contains a number of poisonous organic compounds called alkaloids. A mature head of rye may carry several ergots in addition to non infected kernels. When the grain is harvested, much of the ergot falls to the ground, but some remains on the plants and is mixed with the grain. If the ergot is not removed before milling, the ergotized flour would be converted into bread and other food products and consumed; St. Anthony's fire—for which no cure is known—is the result. The ergot that falls to the ground may be the source of more trouble. Cattle put to graze in the rye fields after harvest are likely to consume enough ergot to bring on abortion of fetuses or death. In the spring, when the rye is in bloom, the ergot remaining on the ground produces tiny, black, mushroomlike bodies that expel large numbers of spores to start a new series of infections. Among the many interesting chemicals in ergot is lysergic acid, the active principle of the psychedelic drug lysergic acid diethylamide ( LSD). Here, then, is a single fungus that can reduce crop yields, cause abortion in cattle, sicken and sometimes kill people, and be used as a source of LSD. On the credit side, ergot provides medical science with drugs useful in inducing labour in pregnant women and in controlling hemorrhage after birth. E The systematic study of fungi began 250 years ago, but humans have been indirectly aware of fungal activity since the first loaf of leavened bread was baked and the first tub of grape must was turned into wine. Yet, even now, few people realize that they are almost constantly either benefited or harmed by these organisms. Fungi are everywhere in very large numbers—in the soil and the air, in lakes, rivers, and seas, on and within plants and animals, in food and clothing, and in the human body; it is this that makes them so important in the human environment. Together with bacteria, fungi are responsible for the disintegration of organic matter and the release, into the soil or atmosphere, of the carbon, oxygen, nitrogen, and phosphorus that otherwise would be forever locked up in undecomposed organic matter. Fungi are essential to many household and industrial processes, notably the making of bread, wine, beer, and certain cheeses. They are used in the production of a number of organic acids, enzymes (biological catalysts), and vitamins and are the sources of a number of antibiotics besides penicillin. Fungi are also used as food: mushrooms, morels, and truffles are epicurean delicacies. Studies of fungi have greatly contributed to the accumulation of fundamental knowledge in biology. Current knowledge of biochemistry and cellular metabolism was derived in part from studies of ordinary baker's or brewer's yeast (Saccharomyces cerevisiae ). Some of these pioneering discoveries were made at the end of the 19th century and continued during the first half of the 20th. From 1920 through the 1940s, geneticists and biochemists who studied mutants of the red bread mold, Neurospora , established the one-gene–one-enzyme theory and laid the foundation of modern genetics. These and other fungi continue to be useful for studying cell and molecular biology, genetic engineering, and other basic disciplines of biology. ^ 10. Match a title with the passage.
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