1. Total Earth’s surface covered by water is

2. Biotic component of the biosphere is not constituted by

3. An increase in carbon dioxide content in the atmosphere would not cause

4. Oxygen is returned to the atmosphere mainly by

5. Low visibility during cold weather is due to

6. Growth of lichens on barren rocks is followed by the growth of

7. Marked temperature changes in an aquatic environment can affect

8. Soil erosion can be prevented by

9. What happens when rain falls on soil without vegetational cover?

10. Oxygen is harmful for