( Respiration ( ( refers ( to ( ( ( how ( ( ( the cells ) ( of ( the ( body ( use oxygen ) ) ) ) ) ( to ( create energy ) ) ) ) and ) ( how ( they ( exhale ( ( carbon dioxide ) ( that ( is ( ( a ( waste product ) ) ( of ( this process ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Respiration)) (VP (VBZ refers) (PP (TO to) (SBAR (SBAR (WHADVP (WRB how)) (S (NP (NP (DT the) (NNS cells)) (PP (IN of) (NP (DT the) (NN body) (NN use) (NN oxygen)))) (VP (TO to) (VP (VB create) (NP (NN energy)))))) (CC and) (SBAR (WHADVP (WRB how)) (S (NP (PRP they)) (VP (VBP exhale) (NP (NP (NN carbon) (NN dioxide)) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (NP (NP (DT a) (NN waste) (NN product)) (PP (IN of) (NP (DT this) (NN process)))))))))))))) (. .)))
Respiration refers to how the cells of the body use oxygen to create energy and how they exhale carbon dioxide that is a waste product of this process.
(ROOT (S (PP (IN In) (NP (DT the) (NN body))) (, ,) (S (NP (NN oxygen)) (VP (VBZ is) (VP (VBN used) (PP (IN by) (NP (NP (NNS cells)) (PP (IN of) (NP (NP (DT the) (NN body) (POS 's)) (NNS tissues)))))))) (CC and) (S (NP (NN carbon) (NN dioxide)) (VP (VBZ is) (VP (VBN produced) (PP (IN as) (NP (DT a) (NN waste) (NN product)))))) (. .)))