Answer:
1) Organisms; ecosystem
2) Species
3) Niche; species
4) Biome; large; Examples of biomes: aquatic, grassland, forest, desert, and tundra
5) predator; prey
6) competition; ?
7) mutualism
8) mutualism; commensalism; parasitism.
9) Clownfish and anemones, Honeyguides and humans, Coral and algae
10) a bird making a nest in a tree, Orchids Growing On Branches, Tree frog on plants
11) mosquito biting a human, fleas on a dog