( ( On ( the ( other hand ) ) ) ( , ( photosynthesis ( also ( ( ( gave rise ) ( to ( ( a ( whole class ) ) ( of ( ( ( organisms ( that ( ( ( ate plants ) and ) ( consumed oxygen ) ) ) ) -- ) ( ( a form ) ( of ( negative feedback ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (PP (IN On) (NP (DT the) (JJ other) (NN hand))) (, ,) (NP (NN photosynthesis)) (ADVP (RB also)) (VP (VBD gave) (NP (NN rise)) (PP (TO to) (NP (NP (DT a) (JJ whole) (NN class)) (PP (IN of) (NP (NP (NP (NNS organisms)) (SBAR (WHNP (WDT that)) (S (VP (VP (VBD ate) (NP (NNS plants))) (CC and) (VP (VBD consumed) (NP (NN oxygen))))))) (: --) (NP (NP (DT a) (NN form)) (PP (IN of) (NP (JJ negative) (NN feedback))))))))) (. .)))
On the other hand, photosynthesis also gave rise to a whole class of organisms that ate plants and consumed oxygen -- a form of negative feedback.
(ROOT (S (NP (NNP Oxygen)) (VP (VBZ is) (VP (VBN made) (PP (IN by) (NP (NP (NNS trees)) (CC and) (NP (JJ other) (NNS plants)))) (PP (IN during) (NP (NN photosynthesis))))) (. .)))