Science Review Units 11-15

4. a kind of soil that is soft when it is wet and hard when it is dry, used to make pottery or bricks.
8. a flat, green plant that grows on rocks and tree trunks.
9. a chemical used to kill harmful insects.
11. the management of forests, including growing young trees and falling mature trees.
13. the gradual wearing of something by natural forces.
14. something that causes serious loss and great damage to many people, such as a flood or tornado.
15. a mixture of decayed plants that is used for enriching soil.

1. plants that do not have leaves or flowers and live on dead or decaying things.
2. very small living things which break down waste.
3. the top layer of earth in which plants grow.
5. the breakdown of rocks by wind, rain, snow, etc.
6. a soft, green plant that grows on stones in damp places.
7. being mixed in a liquid so it becomes part of the liquid.
10. a tunnel or hole in the ground made by an animal.
12. matter, a substance produced by living things.