Answer each question, using a word or expression from the box.

1. What happened to dinosaurs about 65 million years ago? They became extinct.
2. What is the name for a special layer in the Earth’s atmosphere which helps protect our planet? 
3. What word can be used to describe the increasing contact between countries that has a major impact on life today? 
4. What causes problems because it is difficult to dispose of safely? 
5. What have scientists shown to be melting worryingly fast at the North and South Poles? 
6. What does the chemical symbol CO2 represent? 
7. What has been happening in the Amazon area and in other tropical areas like Indonesia and Malaysia? 
8. What problem is a type of air pollution? 
9. What can cause harm to plant or other life when it falls on the land or sea? 
10. What is the Siberian tiger an example of? 
11. What has caused much plant and animal life in rivers in industrial areas to die out? 
12. What is the term for the phenomenon describing the rise in the Earth’s average temperature?