1. Section Review 18-1 Answers
Ecology is the study of the interactions of organisms with each other and with their environment.
An ecosystem is made up of biotic and abiotic parts.
A. Ecosystems are the highest level of environmental organization.
A community is made up of all of the populations that interact in an area.

2. 6. 19km + 9km = 28 km 1,000 m = 1 km Final answer: 28,000m
5. Temperature affects which animals can live in an ecosystem. Water and its abundance affect whether certain plants grow easily in an area.
6. 19km + 9km = 28 km
1,000 m = 1 km
Final answer: 28,000m
7. The populations of organisms that fed on the cordgrass would decrease. The populations of organisms that fed on the organisms that ate the cordgrass would also decrease.

3. 8. All living things depend on other living and non-living things to survive. 9. No, ecosystems do not have borders. Some ecosystems are partially contained, but water, light, and many organisms move freely from one ecosystem to the next.