2 Вариант

1. Read the text and translate the italised extract in written form.

Food Chains and Food Webs

A feeding relationship in an ecosystem is called a food chain, while the totality of the chains constitutes a food web. Often the food webs are quite complex with many different feeding relationships. In addition to primary producers, herbivores and carnivores, omnivores are common in some ecosystems. Many bird species, such as finches and sparrows are examples of omnivores. In autumn they feed on seeds and are herbivores, but in summer they feed their offsprings on insects and are then predators. However, it is often possible to differentiate between the levels described. They are called trophic levels. In an ecosystem there are normally four trophic levels but there might be more or fewer.

The biomass in an ecosystem is very unevenly distributed between the trophic levels. This is because not all of the biomass consumed is converted to the body mass on the next level; rather it is used as energy source for running, flying, swimming, for keeping the body temperature, etc. Thus, no more than 1- 10% of the mass of a lower level becomes biomass on the next level. This explains why an ecosystem normally does not support more than three or four trophic levels. So in the transfer between trophic levels, most energy is lost as heat (much like the engine in an automobile - much petrol is wasted as the

From this description we can see the distinct difference between the transfer of energy and nutrients in the ecosystem. Energy enters the ecosystem through photosynthesis and is gradually lost as heat through the trophic levels.

Nutrients circulate from plants to consumers and decomposers and back to plants. An important environmental issue is how closed this circulation is. With excessive addition of fertilizers to arable land

and by nitrogen added as an air-borne pollutant, the plants may be unable to take up all nutrients, and excess nutrients is then leaking to soil water. This water ends up in rivers and lakes and leads to eutrophication of these and, finally, of the Baltic Sea.

Human use of ecosystem resources, for instance by agriculture, forestry or fishing has had dramatic effects on energy flow, nutrient circulation and biological diversity, locally as well as globally. Sustainability has been suggested as an overall aim for environmental protection work. This implies that our use of ecosystems should not jeopardise central ecosystem functions in the short or long run. The role of the ecologists is to try to establish levels of resource use, for instance fishing quotas that lead to sustainable use of the ecosystems.

To really know if human use of ecosystems is sustainable we need environmental monitoring.

This means that we carefully measure long-term changes in species diversity, nutrient levels and vital ecosystem functions.

TASK1

A. TRANSLATE THE FOLLOWING COLLOCATIONS FROM ENGLISH INTO RUSSIAN:

1. artificial fertilizer;

2. to convert the energy;

3. organic compounds;

4. to fill the role;

5. living conditions;

B. TRANSLATE THE FOLLOWING COLLOCATIONS FROM RUSSIAN INTO ENGLISH:

6. поглощать питательные вещества;

7. получать энергию;

8. пищевая цепь;

9. воздействие на окружающую среду;

10. органическое вещество.

TASK2

FILL IN THE MISSING PREPOSITION:

1. In autumn omnivores feed … seeds and are herbivores, but … summer they feed their offsprings … insects and are then predators.

2. Human use … ecosystem resources, … instance … agriculture, forestry or fishing has had dramatic effects … energy flow, nutrient circulation and biological diversity.

3. Ecosystem ecology, sometimes referred … as system ecology, is concerned … the flow … energy and circulation … matter … a whole ecosystem.

4. Soils animals, such as earthworms make … the first stage … the decomposition … detritus, while fungi and bacteria take care … the final decomposition.

5. The study … ecology gives us an understanding … which basic principles man has to observe … order to create a society that is … the long term … harmony … the environment.

6. We may sum … four ecological principles … sustainability to be used as guidelines.

7. The violation … basic principles will bring us … pollution.

8. Nutrients circulate … plants … consumers and decomposers and back … plants.

9. The role … ecologists is to try to establish levels … resource use, … instance fishing quotas that lead … sustainable use … the ecosystems.

10. The intimate couplings … the environment and the species living there will influence the balance … the ecosystem and the living conditions … its members.

TASK3

CHOOSE THE BEST VARIANT TO COMPLETE THE SENTENCES AND TRANSLATE THEM INTO RUSSIAN:

1. The majority of plants (get, receive, obtain) their energy directly from sunlight using green chlorophyll and sometimes additional pigments.

2. Plants (transform, turn into, convert) the energy from sunlight into energy stored in carbohydrates and other organic compounds.

3. Earthworms (compose, make up, arrange) the first stage in the decomposition of detritus.

4. The food webs are quite (complex, composite, difficult) with many different feeding relationships.

5. Today the rate of species (extinction, disappearance, dying out) is very large and we are losing biodiversity at a high rate.

TASK 4.

MATCH THE WORDS WITH THEIR DEFINITIONSAND TRANSLATE THEM:

1. herbivore; 2. carnivore; 3. omnivore; 4. to graze; 5. biodiversity; 6. fertilizer; 7. detritus; 8. decomposer; 9. biomass; 10. photosynthesis;

a. the variety of plant and animal life in the world or in a particular habitat; b. a plant-eating and a flash eating animal or person; c. a flash-eating mammal; d. to feed on herbage or pasture; e. a plant-eating animal; f. loose material (as rock fragments or organic particles) that results directly from disintegration; g. a chemical or natural substance added to soil or land to increase its fertility; h. the process by which green plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water. i. the total quantity or weight of organisms in a given area or volume. j. any of various organisms (as many bacteria and fungi) that return constituents of organic substances to ecological cycles by feeding on and breaking down dead protoplasm;