insects would appear. The wind would blow the seeds of small trees. These trees would grow and birds and animals would appear.

Evolution. During long periods of time ecosystems evolve. The evolution of an ecosystem is caused by factors inside and outside it.

Consider the evolution of the atmosphere: when life began there was no oxygen in the atmosphere. Consequently, the sun's rays prevented life from developing on land. The first living organisms developed under the sea. Afier the evolution of photosynthesis, the oxygen in the atmosphere increased and life expanded. Complex living organisms developed. As the oxygen in the atmosphere increased, a layer of ozone was formed, life would be impossible without it on the surface of the Earth.

Today life on the Earth is in danger: man himself might destroy the equilibrium of ecosystem by pollution, extinction of wildlife and unreasonable utilization of the globe's material resource.

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Post-text exercises

I. Answer the questions:

What parts does an ecosystem consist of ?

How many major components are there in an ecosystem? How is an ecosystem defined?

What do the main processes include in ecosystems ? What process is called a food chain ?

What process do materials cycles include ?

What can you tell about development of an ecosystem? What can you tell about evolution of an ecosystem?

2.Decide whether the following statements are true or false.

1.There are seven major components in an ecosystem.

2.Only green plants are able to manufacture food from simple inorganic substance.

3.The first living organisms developed on the earth.

4.Decomposers enable chemical substances to return to the physical environment.

5.Material cycles include cycles of nitrogen, carbon, oxygen, water and mineral salts.

6.The proper transfer of energy through an ecosystem by the producers, the consumers and the decomposers is called a food chain.

3. Give definitions of the following words:

producers, substance, compound, nitrogen, carbon, decomposers, evolution, oxygen, layer, food chain, microorganisms.

1.One thickness of matter or substance.

2.Substance consisting of two or more elements chemically united in fixed proportions by weight.

3.A gas without colour, smell or taste, necessary for all life, which forms about one fifth of the air.

4.A gas without colour, which forms about four fifths of the air.

5.Non-metallic chemical element occurring in carbon-dioxide and carbonates and in all organic compounds.

6.Kind of material having more or less constant properties.

7.Organisms (specifically, plants) that can produce their own food.

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8.Figure of speech describing the dependence of heterotrophs on other organisms for food, progressing in a series beginning with primary producers (plants) and ending with the largest carnivores.

9.Living organisms so small they can only be seen through a microscope.

10.Organisms such as bacteria and fungi that decompose dead plants and animals.

11.The long-term process through which a population of organisms accumulats genetic changes that enable its members to successfully adapt to environmental conditions and to better exploit food resources.

4.Match the following English words with their Ukrainian equivalents:

5. Group the following words into synonym pairs:

various, utilization, chain, to obtain, to start, to affect, to improve, use, main, to manufacture, earth, link, to begin, to influence, to call, chief, species, to return, to travel, forest, to make better, to name, substance, to come back, to move, wood, matter, major, different, kind, to produce, globe, to get.

6. Group the following words into antonym pairs:

primary, unreasonable, secondary, to build, living, reasonable, composer, to increase, to disappear, outside, to narrow, possible, to break, proper, non-living, decomposer, to decrease, long, after, complex, impossible, improper, to die, to move, to appear, short, before, simple, with, to live, to stop, inside, to expand, without.

7. Translate the following word combinations in written form:

farm crop cultivation, farm crop cultivation improvement, plant protection measures, great soil erosion difficulties, industry and

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