( ( The circulation ) ( then ( ( transfers ( ( oxygen ( rich blood ) ) ( to ( ( the tissues ) ( where ( it ( ( diffuses ( by ( simple ( concentration gradients ) ) ) ) ( into ( the tissues ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (DT The) (NN circulation)) (ADVP (RB then)) (VP (VBZ transfers) (NP (NP (NN oxygen) (JJ rich) (NN blood)) (PP (TO to) (NP (NP (DT the) (NNS tissues)) (SBAR (WHADVP (WRB where)) (S (NP (PRP it)) (VP (VBZ diffuses) (PP (IN by) (NP (JJ simple) (NN concentration) (NNS gradients))) (PP (IN into) (NP (DT the) (NNS tissues)))))))))) (. .)))
The circulation then transfers oxygen rich blood to the tissues where it diffuses by simple concentration gradients into the tissues.
(ROOT (S (NP (NNP Oxygen)) (VP (VBZ is) (VP (VBN transferred) (PP (IN into) (NP (DT the) (NN bloodstream))) (PP (IN by) (NP (JJ simple) (NN diffusion))))) (. .)))