Chapter 4 Lesson 4

5. What organisms do to survive changes to their ecosystem.
6. Car exhaust and cities dirty the air.
7. a man-made lake on the Colorado river that flooded the river and changed the environment.
8. Moving earth that slides down mountains and hills.
10. These change ecosystems over time. They can be caused by nature, animals, or humans, and can damage the environment.

1. After a fire, doing this can help animals return to their homes to live.
2. They can change the tops of mountains and create new land.
3. when trash and waste contaminate water and make it unsafe to drink.
4. People change ecosystems when they use the materials like trees to build houses and rocks and sand to build roads.
9. animals and people build them to store water. They also change the way rivers flow.