Понимание структурно-смысловых связей в тексте

The term ‘biosphere’ was coined in 1875 by the geologist, Eduard Suess, but it was Vladimir Vernadsky A ______. He believed that all living organisms together with their environments make up the biosphere. These environments include the air, land, rocks and water. The exact thickness of the biosphere on Earth is difficult to calculate, but most scientists would agree that it is from about 5,000 metres above sea level to around 9,000 metres below sea level. Thus, there is a 14-kilometre zone B ______.

The biosphere is important because it is all of life. Without the biosphere, Earth would be a lifeless planet like all the others in our solar system. Also, the biosphere could not exist without water. Water is essential for all living organisms on Earth and has played a very important role in the evolution of life on our planet. Life on Earth began approximately 3.5 billion years ago in the oceans. At that time, Earth was very different from C ______.

The biosphere is like a ladder. This ladder is known as the food chain, and all life depends on the first step of the ladder D ______. Animals eat the plants; bigger animals eat the smaller animals, and so on. In this way, all organisms are closely connected to their environment.

The biosphere is E ______. It gives us our food, water and the air that we breathe. Everything we need in order to grow and survive comes directly from the bio- sphere, so it is important to protect it. However, humans have had a huge impact on the biosphere. Sometimes this has been good, but at other times it has been very destructive.

Scientists are very concerned about the future, particularly F ______. It is very important to try and prevent any permanent damage, or we will destroy ourselves.

1. how people will affect the environment
2. within which life exists
3. who recognised its ecological importance
4. what keeps us alive
5. what it is today
6. which will cause environmental damage
7. which is made up of plants