( ( ( The ( oral cavity ) ) ( -LRB- ( ( the mouth ) -RRB- ) ) ) ( ( is ( where ( ( ( the ( mechanical ( and ( chemical digestion ) ) ) ) ( of food ) ) begins ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ oral) (NN cavity)) (PRN (-LRB- -LRB-) (NP (DT the) (NN mouth)) (-RRB- -RRB-))) (VP (VBZ is) (SBAR (WHADVP (WRB where)) (S (NP (NP (DT the) (JJ mechanical) (CC and) (JJ chemical) (NN digestion)) (PP (IN of) (NP (NN food)))) (VP (VBZ begins))))) (. .)))
The oral cavity (the mouth) is where the mechanical and chemical digestion of food begins.
(ROOT (S (NP (NNP Digestion)) (VP (VBZ begins) (PP (IN in) (NP (DT the) (NN mouth)))) (. .)))