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Tropical rain forests are home to half the worlds plant and animal species, and they play a critical role in purifying the Earths air and water. Land development in the past 30 years has destroyed great regions of the tropical rain forest.

Read the facts below about the rain forest. Use the question prompts to make complete sentences in the present perfect tense about the great environmental problems that we face if we lose the rain forest. The first problem has been done for you as an example.

1. Three thousand years ago, tropical rain forests covered three million square miles of the Earths surface; now they cover half that area.

(How much of the worlds tropical rain forest have we already lost?)

We have already lost one-half of the worlds tropical rain forests.

2. In Central America, the rain forest was formerly three times as large as it is today.

(How much of the rain forest in Central America has already disappeared?)

3. There may be 30 million different plant and animal species on Earth; scientists know about only 1.4 million.

(What percent of the Earths plants and animal species have scientists discovered? What percent have they not yet discovered?

4. The rain forest contains 2,500 kinds of edible fruits; most people know only a few of them.

(How many of the rain forest plants with possible medicinal value have scientists examined? How many have they not yet examined?)

5. About one quarter of all Western medicines have come from tropical plants.

(How many medicines have come from other than natural sources?

6. Scientists have found 70 plants from the rain forest to be possible cures for cancer; probably more have healing power that is still undiscovered.

(How many plants for cancer have scientists not yet discovered?)

7. The survival rate ( ) for leukemia (cancer of the blood) in 1980 was 20 percent; now the survival rate is 80 percent because of a drug found in the rain forest of Madagascar.

(How has the rain forest plant drug improved the survival rate for children with leukemia?

Exercise 3. Discuss the text answering the questions.

1. In what countries did early civilized people start cultivating plants?

2. Why did ancient people test different plants upon themselves?

3. Can garlic be used for the prevention and treatment of a wide range of health problems? Give the examples.

4. Does Valerian have fewer or more side effects than prescription sleeping pills?

5. What can you say about useful properties of Echinacea?

6. What plants contain cardiac glycosides used to treat heart problems?

7. Is it necessary to consult a doctor before taking herbal medicine. If, yes, why?

8. What other purpose may plants be used for? Illustrate your answer with the examples.

Read and translate without a dictionary.

There is a growing number of studies suggesting that animals use plants as drugstores. Biologists suspect that animals doctor themselves by using plants as preventive measure.

Chimpanzees often eat leaves of the shrub () Vernonia amygdalin when they are tired or sick. The plant is used by African tribes to cure the same symptoms. Similarly chimpanzees eat leaves of Aspilia, a member of a sunflower family. These leaves contain thiarurbine A, a red sulfur-containing oil that kills pathogenic bacteria and parasitic worms (). Humans use extracts of the oil as anticancer drugs.

World rhesus monkeys often eat dirt with their food. That dirt contains much kaolin, a clay that detoxifies many poisons and is active ingredient in Kopectate an antidiarrheal medicine




Test 1

From wild rose fruit The 1 of wild rose is one of the plant products which is the source of vitamin C. During investigations of the fruit of different 2 of wild rose growing in different geographical conditions it was found that some species were very rich in vitamin C, whereas others were very poor. The genus Rosae, perennial wild growing bush has high vitamin C 3. Particularly vitamin rich species are Rosae cinnamonia, containing up to 20 mg per cent of ascorbic acid, Rosae rugosae having 4 content of vitamin C up to 4 mg per cent. One of the causes of small yield of ascorbic acid from some species of wild rose is the presence of oxidation ferments in the 5. Ascorbic acid is not equally distributed in the fruit of the wild rose. Most of it is in the soft flesh and none in the 6. The time of 7 is an important factor influencing yield of vitamin C. When the fruit is orange red it contains as much ascorbic acid as when it is quite 8. By freezing, the fruit loses up to 51 per cent of ascorbic acid; by drying it is possible to 9 80-90 per cent of the original content. The 10 conditions of drying at 80-1000 C diminishes the loss of vitamin C.     1) a) bark; b) root; c) stem ; d ) branch 2) a) transhort ; b) vascular; c) productive; d) tube 3) a) flovers; b) seeds; c) roots; d) top 4) a) absorbing; b) maintaining; c) giving; d) transporting 5) a) growth; b) harvesting; c) collection; d) production. 6) a) dirt; b) earth; c) soil; d) region 7) a) produce; b) take; c) save; d) store 8) a) food; b) nutrients; c) water; d) food staff 9) a) fruits; b) inflorescences; c) leaves; d) branches 10) a) source; b) nucleus; c) fruit; d) seeds  


Test 2

Stems support leaves, the solar collector of plants. They produce carbohydrates. Parenchyma cells in 1 store large amounts of o starch () and water. The 2 system of stems maintains () the aquatic environment in leaves and transports sugars and other solutes between leaves and 3. Leaves are the most active organs of plants. The most important of their functions is 4 sunlight for photosynthesis. To do so they expose large amounts of surface area to the environment. We have long known that that roots are critical for plant 5 and most plants die when separated from roots. To locate water and minerals roots permeate () the 6. They 7 large amounts of energy reserves. Roots absorb large amounts of water and dissolved 8 from the soil and transport them to and from the shoot. The most familiar reproductive structures of plants are flowers, 9 and seeds. Flowers have 10 in their container, which become fruits.       4) a) slight; b) bigl; c) smaller; d) as small as 5) a) seeds; b) inflorescence; c) fruit; d) top 6) a) root; b) rhizovne; c) seeds; d) buds 7) a) maturing; b) ripening; c) growing; d)harvesting 8) a) ready;b) ripe; c)grown; d) harvested 9) a) preserve; b) store; c) collect; d) select 10) a) useful; b) possible; c) proper; d) effective  


Date: 2014-12-22; view: 1680

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