What organ system breaks down chewed food to a form your cells can use.

the dark variety, as they are not visible on the dark tree barks

explanation:

there's the proffessional site that will you.

1. efficient use of space

2. elimination of groundwater contamination

3. energy generation

4. lower carbon footprint

more words for this could be abiotic and biotic

abiotic: living organisms within an ecosystem

biotic: non-living organisms within an ecosystem