Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

An Ecosystem is always .

Ecosystems will fail if they do not remain in [?].

A salt water aquarim is a ecosystem.

Ocean corals will usally flourish unless people .

The living part of an ecosystem is sometimes called a .