Ecosystems

3. Type of plant or animal that has died out completely.
4. A factor that controls populations in its environment.
5. Community of organisms interacting with their environment.
9. The study of the relationship between organisms and their environment.
10. An organism that floats on the water.
11. Type of animal that is in danger of becoming extinct.
15. Group of one or more species living in a certain habitat.
16. The protection of valuable things especially forests, wildlife, and natural resources.
17. Habitat that is suitable for a particular organism to live in.

1. Gradual growth of new organisms in an environment.
2. An organism that is bottom-dweller.
6. Group of living things that interact in an ecosystem.
7. Type of plant or animal that is in danger of becoming endangered.
8. Period of time in history when a large part of the earth was covered with ice.
12. An organism that swims in the water.
13. One of the groups into which animals and plants of the same genus are divided according to their characteristics.
14. Place or natural conditions in which an organism lives.