( Urea ( ( ( ( ( ( forms chiefly ) ( in ( the liver ) ) ) , ) and ) ( is ( ( eliminated mostly ) ( in ( the urine ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Urea)) (VP (VP (VBZ forms) (ADVP (RB chiefly)) (PP (IN in) (NP (DT the) (NN liver)))) (, ,) (CC and) (VP (VBZ is) (VP (VBN eliminated) (ADVP (RB mostly)) (PP (IN in) (NP (DT the) (NN urine)))))) (. .)))
Urea forms chiefly in the liver, and is eliminated mostly in the urine.
(ROOT (S (NP (NNP Urea)) (VP (VBZ is) (VP (VP (VBN made) (PP (IN in) (NP (DT the) (NN liver)))) (CC and) (VP (VBN excreted) (PP (IN in) (NP (NN urine)))))) (. .)))
Urea is made in the liver and excreted in urine.