Environmental Science 3

4. a measure of how acidic or basic a substance is.
7. the long-term prevailing weather conditions at a particular place.
8. the process of removing salt from salt water.
10. the distance from the equator measured in degrees north or south of the equator.
11. an organism that lives in or on another organism and feeds on it.
13. a relationship in which different individuals or populations attempt to use the same limited resource.
17. a relationship in which one species benefits and the other species is neither harmed nor helped.
18. are organisms that cause illness or disease.

1. the set of individuals within a species living in the same place at the same time.
2. the number of different species in a given area.
3. the movement of people from rural areas to cities.
5. water that safe for drinking.
6. the nonliving parts of the ecosystem, including air, water, rocks, sand, light, and temperature.
9. the intensity of sound is measured in units.
12. species a species that is likely to become extinct if protective measures are not taken immediately.
14. a mixture of smoke and fog.
15. a piece of DNA that codes for a specific trait that can be inherited by an organism’s offspring.
16. The clearing of trees from an area without replacing them.