Exercise 9 Study questions on TEXT A. Work in pairs practising questions and answers.

1. Could you speak on the importance of water as a constituent of protoplasm?

2. What element is present «in all organic compounds?

3. What are the three main clashes into which organic compounds are divided?

4. What is the name of (-NHg) group?

5. Could you name one of the simplest proteins?

6. What nucleic acids are important in cells? What nucleic acid is genetic material?

7. Who proposed the now-famous model of DNA?

8. Where is DNA found?

9. What is meant by the "genetic code"?

10. Could you explain the role of RNA in a cell?

PRE – TEXT NOTES

to mold = to shape =to form

studies in the wild =studies in nature

predators – хищники

аnimals that are preyed on as adults - животные, которые служат добычей хищников в зрелом возрасте

conversely – наоборот

...bear the brunt of... – несут на себе основной удар

hardier offspring – крепкое и выносливое потомство

to render ...dull =to make ....not bright

to bestow the offspring with =to give the offspring...

to come through with flying colors =to make a great success

TEXT B

Sex, predators and the theory of evolution

(Observing Darwin’s ideas in action)

What shapes a creature's life course and behavior? More than 130 years ago, Charles Darwin laid out his elegant and then shocking theory that it was natural selection, the survival of individuals most suited to the environment, that molded species over evolutionary time. But until very recently, Darwin's ideas remained unproved. Now, for the first time, studies in the wild are rigorously demonstrating the particulars of how evolution works.

Last month, David Reznick, an evolutionary ecologist at the University of California at Riverside, published the results of an 11-year experiment involving guppies living in the Aripo River of Trinidad. The experiment proved that predators are among the principal forces driving the evolution of species, just as predicted by a mathematical model that modern biologists had formulated to refine Darwin’s theme.

According to the model, animals that are preyed on as adults will evolve to produce as many babies as they can, as early in life as possible, "If your chances of dying young are good, then having babies yearly is important", says Reznick. However, the earlier a species reproduces, the sooner it bums out, so to speak, and the shorter its life span. Conversely, whose juveniles bear the brunt of predatory attacks, tend to have their young later in life, in effect choosing to bear hardier offspring over a longer adult life.

The experiment that Reznick devised, along with his colleagues, was delightfully uncomplicated. The researchers tested the mathematical model simply moving 200 guppies from the base of a 20-foot waterfall in the Aripo River, where predatory fish eat only adult guppies, to the top of the waterfall. There, the single predator is a killifish, a species that devours only young guppies.

After 60 generations, the experimental guppies had evolved in their new environment just as the model predicted. The fish now reach sexual maturity nine days later when they first give birth. What's more, they have fewer offspring in their first brood, apparently saving themselves for future breeding opportunities.

Reznick’s is only one of several recent studies verifying Darwin's grand theory in nature. In others, for instance, parasites are proving to be an even more potent agent of evolutionary change than predators. Marlene Zuk, a colleague of Reznick at Riverside, recently completed a study demonstrating that parasites affect how female jungle fowl, the wild ancestors of barnyard chickens, choose their mates. She found that nematode parasite, which lives in the gut, renders the eye and comb of the male fowl dull and consequently unattractive to females. The females prefer instead cocks bright of eye and comb, who will bestow their offspring with genes that will make them resistant to parasites.

Taken together, studies such as Reznick's and Zuk's, strike a resounding blow to all who would doubt veracity of evolution. It has taken more than a century, but Darwin's theory is finally being put to the test, as it is coming through with flying colors.

COMPREHENTION CHECK

Exercise 1.Read the text quickly and note its chief points by making a list of key words, topic sentences, names, places and numbers. Then re-read it for the specific information that will help you to answer the following questions.

1. Do we know in detail how evolution works?

2. Is "adaptation" the only factor contributing to evolution? Are there any other principal factors contributing to evolutionary changes in species?

3. Studies in the wild conducted by evolutionary ecologists are very helpful in understanding the particulars of evolutionary changes. How many experiments are described in the article and who conducted them?

4. What model is tested in the first experiment? Does it prove that there is a certain relationship between predatory attacks on a species and the period when it begins to reproduce?

5. What kind of fish was chosen for the first experiment?

6. How many generations of the experimental fish did it take to prove evolutionary changes?

7. Who conducted the second experiment which proved that sex relations among animals (the way they choose their mates) may affect the genetic composition of the offspring and may lead to evolutionary changes?

8. Which is the correct relationship established in the second experiment:

Rematode parasite → the specific genes → color of the eye and comb

Rematode parasite → color of the eye and comb → the specific genes

9. Do you think that Darwin's theory was successfully tested?

Exercise 2 .Highlight TEXT В taking the following steps:

Step 1:Read and translate TEXT В into Russian.

Step 2: Read carefully TEXT В making a list of key words and topic sentences.

Note 1: Key words and key terms are usually repeated; similarity of meaning or parts of meaning turns them into key words.

Note 2: Topic sentence summarizes the content of the whole paragraph.

Step 3: Look through the text quickly giving special attention to transitional words that help to connect ideas (but, though, despite, etc.).

Step 4: Look for such signals as the heading (Why is the text entitled the "Sex, predators and the theory of evolution"?), introductory and concluding paragraphs, names and numbers.

Step 5: Prepare for making an oral report in class on different aspects of the Darwin’s theory of evolution.

UNIT 5

PRE-TEXT TASK

Study carefully the meaning of the following phrases and word-combinations to avoid any difficulty in working through TEXT A.

	environmental protection	защита окружающей среды
	as well as	так же ... как
	agricultural pollution control	контроль за загрязнением в сельском хозяйстве
	genetic consequences of pollution	генетические последствия загрязнения окружающей среды
	indiscriminate dumping of materials on land	беспорядочное вываливание отработанных веществ и материалов на землю
	careless disposal of pesticides	небрежное использование пестицидов
	fall-out	выпадение в виде осадков
	...most of it being brought by winds	причем большая ее часть приносится ветрами
	eventually	в конечном итоге, в конце концов
	becomes upset	становится нарушенным
	an ever-thinning ozone layer	постоянно истончающийся озоновый слой
	ever-frozen	вечномерзлый
	evergreen	вечнозеленый
	ever-growing	постоянно растущий
	to allow	делать возможным, приводить к ...
	...speed and scale of change that human beings are inflicting on the world	скорость и масштабы тех отрицательных последствий /изменений/, которые люди наносят окружающей природе
	rain forests	тропические леса
	yet they only evolve to match -specific varieties of wheat	однако они развиваются только в том случае, если сочетаются с определенными сортами пшеницы
	conservative forecasts	заниженные прогнозы

TEXT A

The Science of Ecology

People all over the world are concerned about ecological and environmental protection1 problems. Ecology is the scientific study of how organisms interact with their environment. The word "ecology" comes from the Greek word "oikos" (house). The term was first introduced by the German biologist E.Hackel in 1870, and since the late 1960s it has become a subject of international interest. A key word in the definition of ecology is INTERACT. So numerous are each organism's interactions with other living things and the physical environment that biologists organize ecology the science of interactions, into a hierarchy of four levels: populations, communities, ecosystems and the biosphere. "Environment" describes the conditions surrounding an organism. Organisms interact with the other living things that collectively constitute their BIOTIC environment, as well as with the non-living physical surroundings (air, water, soil, light, temperature) that make up their ABIOTIC environment. A permanent change in any of these conditions, for example, a change in the intensity of the light, is a change in the environment.

Highly industrialized states cannot ignore the problems of environmental protection. The practical results of the state policy in environmental protection include agricultural pollution control, the study of man's influence on the climate, the biological and genetic consequences of pollution .protection of rare and vanishing plants and animals.

The main risks of land pollution lie in the indiscriminate dumping of materials on land, careless disposal of pesticides and chemicals, fall-out of materials from the atmosphere. For example, every day Sweden receives more than 1,000 tons of sulphur from the air, most of it being brought by the winds from other countries. This has been dropping on Swedish soil for the last 30 years and the results are shocking: 18,000 of the country's 85,000 lakes are now acidified, 4,000 have no fish left and about another 6,000 have been seriously damaged.

To understand how the process works, imagine a factory in Britain. It needs heat for its manufacturing, so it burns oil. This has a high sulphur content, which turns into sulphur dioxide (SO2) after the oil is burnt. The S02 can travel hundreds or thousands of kilometers, depending on the wind, and combining with oxygen it forms sulphur acid (H2SO4.). The acid becomes a cloud, and eventually falls to earth as rain. The water being polluted, the biological balance of lakes becomes upset .

Recent scientific research suggests that the growing industrial use of chlorine compounds: called chlorofluorocarbons (CFCs) is responsible for destroying the protective layer of ozone around our planet. CFC is a gas commonly used in aerosol sprays, air cooling systems in refrigerators and air-conditioning. Researchers suggest that the level of CPCs in the atmosphere is actually increasing by 5$ each year. An ever-thinning ozone layer could eventually allow a more harmful form of radiation, known as ultra Violet C. Laboratory experiments have shown that UVC can penetrate cells in the body and irreparably damage the nucleic acids and proteins which are the building blocks of life.

There is another aspect of the huge speed and scale of change that human beings are inflicting on the world . A powerful symbol of that change is the simple act of felling trees.

In the past 30 years, for example, people have been cutting down forests of Pakistan, Nepal and Tibet. This leaves fertile Himalayan hills naked, unprotected from the heavy rains. The Amazonian jungle is being destroyed at the rate of 29,000 square miles in a. year. Trees are vital part of the water cycle and of course they give us the oxygen that we breathe. And cutting down the rain forests kills the plants which help us fight diseases. 40% of our drugs, our medicines, are derived from plants and most of those come from the tropical rain forests. Those plants also help fight the diseases that threaten our food. The funguses and moulds that attack wheat, for example, are continually growing stronger. Yet they only evolve to match specific varieties of wheat. So plant breeders beat the funguses by changing the varieties. New genes which a plant breeder needs to change a variety come from wild plants. And if we lose those wild strains, the field could be devastated and mankind would starve.

The crucial ecological and environmental problems we face now are largely those of population which will really hit us in the middle of the next century. 80,000,000 new human beings are born each year. Even the most conservative forecasts project a total world population of around 6 billion by the turn of the century.

COMPREHENSION CHECK

Exercise 1.Explain in English or in Russian what is meant by:

1. …are concerned about ecological problems

2. ...that collectively constitute their biotic environment

3. ...vanishing plants and animals

4. ...85,000 lakes are now acidified

5. to understand how the process works...

6. ..which turns into sulphur dioxide

7. ...can penetrate cells in the body

8. ...irreparably damage the nucleic acids

9. our medicines are derived from plants...

10. plant breeders beat the funguses by changing the varieties