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Evolution

Life, as it is currently understood, is known to exist only on the planet Earth. The origin of life is still a poorly understood process, but it is thought to have occurred about 3.9 to 3.5 billion years ago on the earth that had a substantially different environment than is found at present. These life forms possessed the basic traits of self-replication and inheritable traits. Once life had appeared, the process of evolution by natural selection resulted in the formation of ever-more diverse life forms. Species that were unable to adapt to the changing environment and competition from other life forms became extinct.

The appearance of photosynthesis in very basic forms of plant life worldwide allowed the sun's energy to create conditions allowing for more complex life. As a result oxygen accumulated in the atmosphere and gave rise to the ozone layer. The incorporation of smaller cells within larger ones resulted in the development of yet more complex cells called eukaryotes. Cells within colonies became increasingly specialized, resulting in true multicellular organisms. With the ozone layer absorbing harmful ultraviolet radiation, life colonized the surface of Earth.

1. Grammar Revision. Find in the text and translate the sentences with:

    1. Infinitive

    2. Infinitive constructions

2. Answer the questions.

  1. How would you define the biosphere?

  2. How much biomass does the entire Earth contain?

  3. How many species of plants and animals have been identified to date?

  4. What is the biota?

  5. What are the limits of the “film of life”?

  6. When did the idea of biosphere originate? Who was the first to propose the term biosphere?

  7. When did the life on Earth appear?

  8. Why did some species become extinct?

  9. When did more complex life emerge?

3. Ask your partner some more questions on the text.

4. Substitute the words in bold type for their synonyms:

covering, appeared, change, combining, accidentally, life,delicate, emerged, circle

  1. The biosphere is the part of Earth's outer shell.

  2. The idea of biosphere originatedrather casually more than a century ago.

  3. The biosphere is the global ecological system integrating all living beings and their relationships.

  4. Over nine-tenths of the total biomass on Earth is plants, on which animals depend very heavily for their existence.

  5. The number of individual species is constantly in some degree of flux.

  6. Part of the biosphere containing the highest concentration of living matter is the Earth’s thin and fragile“film of life”.

  7. The biosphere is a complex system of energy use and material cycling.

  8. The idea of biosphere originated rather casuallymore than a century ago.

  9. Life is thought to have occurredabout 3.9 to 3.5 billion years ago.

5. Finish the sentences using the text.

  1. The biosphere is the part of Earth's outer shell …

  2. From the broadest geophysiological point of view, the biosphere is …

  3. Currently the entire Earth contains …

  4. Over nine-tenths of the total biomass on Earth is …

  5. More than 2 million species of …

  6. The number of individual species is constantly …

  7. The total number of species is presently …

  8. Biosphere is a relatively thin life-supporting layer around the Earth …

  9. Part of the biosphere containing the highest concentration of living matter …

  10. The biosphere is a complex system of …

  11. We can divide the biosphere into …

  12. The biotic part of the biosphere consisting of fauna and flora …

  13. The idea of biosphere originated rather casually …

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