Here's what I came up with:
1. Scavengers
2. Community
3. Parasitism
4. Competition
5. Food chain
6. Predator-prey
7. Dominant species
8. Population
9. Parasitism
10. Commensalism
11. Mutualism
12. Predator-prey
13. Decomposer
14. Scavengers
15. Mutualism
16. Dominant species
17. Predator- prey
Necessary because it keeps heat in and keeps the planet at the right temperature for life.
It can harm the planet if more pollution occurs and the greenhouse gas effect traps too much heat and causes global warming
Some unicellular organisms are similar to animals because they have the ability to move.
Third option
Termites, koalas, field mice, and deer.