Across
4. organisms that produce their own food
5. network of related food chains
8. ecosystems where species are endangered
9. organisms that get nutrients by eating other organisms
10. a type of consumer that eats plant material
12. tiny plants and animals that break down dead materials into nutrients
14. the process plants use to make food from sunlight, water and carbon dioxide
16. a partnership between organisms that helps one or both of them survive
17. change of water from a liquid to a gas state
18. non-living factors that affect organism survival, such as water availability, pollution, and temperature range
19. the number of different organisms in an ecosystem
20. water vapor forms clouds and returns to Earth

Down
1. plants and animals in an area, functioning together with their surroundings
2. an animal killed for food
3. consumers that feed upon organisms that other organisms have killed
6. green material in plant leaves
7. a type of consumer that eats animal material
11. water lost to the atmosphere by the activities of plants
13. natural home of a plant or animal
14. an animal that kills other animals for food
15. living factors that directly or indirectly affect an organism in its environment, such as disease, predators, and parasites