( It ( ( is ( ( the ( ( ( first and ) shortest ) part ) ) ( of ( ( the ( small intestine ) ) ( where ( ( most ( chemical digestion ) ) ( takes place ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ is) (NP (NP (DT the) (ADJP (JJS first) (CC and) (JJS shortest)) (NN part)) (PP (IN of) (NP (NP (DT the) (JJ small) (NN intestine)) (SBAR (WHADVP (WRB where)) (S (NP (JJS most) (NN chemical) (NNS digestion)) (VP (VBZ takes) (NP (NN place))))))))) (. .)))
It is the first and shortest part of the small intestine where most chemical digestion takes place.
(ROOT (S (PP (IN In) (NP (DT the) (NN body))) (, ,) (NP (NN chemical) (NN digestion)) (ADVP (RB mainly)) (VP (VBZ takes) (NP (NP (NN place)) (PP (IN in) (NP (DT the) (JJ small) (NN intestine))))) (. .)))
In the body, chemical digestion mainly takes place in the small intestine.