( Plants ( ( are ( ( the ( ` ( producers ' ) ) ) ( ( on which ) ( ( all ( other life ) ) depends ) ) ) ) . ) )
(ROOT (S (NP (NNS Plants)) (VP (VBP are) (NP (NP (DT the) (`` `) (NNS producers) ('' ')) (SBAR (WHPP (IN on) (WHNP (WDT which))) (S (NP (DT all) (JJ other) (NN life)) (VP (VBZ depends)))))) (. .)))
Plants are the 'producers' on which all other life depends.
(ROOT (S (NP (DT All) (VBG living) (NNS organisms)) (VP (VBP are) (ADJP (JJ dependent) (PP (IN on) (NP (NNS plants)))) (SBAR (IN because) (S (NP (NNS plants)) (VP (VBP are) (NP (NNS producers)))))) (. .)))