2. ________________________ a relationship in which one species benefits and the other is unaffected.

3. Different species sharing resources tend to evolve ______________________________. 

4. A ______________________ is the role an organism plays in its ecosystem.  

5. _______________________ occurs when different species try to use the same resources. 

6. ________________________ is the process by which two or more species evolve in response to one another. 

7. Examples of coevolution include the interactions between flowering plants and _____________________.

8. ________________________ is a close, long-term relationship between species.  

9. ________________________ is when one species lives on or in another species (the host).

10. _______________________ is the ability of an ecosystem to resist change.  

11. Human impact on the environment cannot be avoided but must be _________________.

12. More diverse ecosystems are usually __________________ than less diverse ecosystems. 

13. Ecosystems develop by ___________________, whereby a progression of species replacements take place.  

14. Succession is driven by ________________________. 

15. The _______________ of species within an ecosystem is related to the size of the ecosystem and its latitude. 

16. ESSAY: How can humans have a negative impact on ecosystems?