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!

Heterotrophs are divided into
and decomposers. An
ecosystem exist without consumers
but cannot be sustained without
. Without the decomposers
the material would accumulate
causing degradation and
later death the living beings.