( Oxygen ( ( ( gets ( into ( the atmosphere ) ) ) ( by ( photosynthesis ( of ( land ( and ( sea plants ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Oxygen)) (VP (VBZ gets) (PP (IN into) (NP (DT the) (NN atmosphere))) (PP (IN by) (NP (NP (NN photosynthesis)) (PP (IN of) (NP (NN land) (CC and) (NN sea) (NNS plants)))))) (. .)))
Oxygen gets into the atmosphere by photosynthesis of land and sea plants.
(ROOT (S (NP (NP (DT The) (NN process)) (ADJP (JJ responsible) (PP (IN for) (NP (NP (DT the) (NN presence)) (PP (IN of) (NP (NP (NN oxygen)) (PP (IN in) (NP (PRP$ our) (NN atmosphere))))))))) (VP (VBZ is) (NP (NN photosynthesis))) (. .)))