( ( ( Some animals ) ( -LRB- ( ( ( amphibians and ) reptiles ) -RRB- ) ) ) ( ( have ( ( ( a ( three-chambered heart ) ) , ) ( ( in which ) ( ( ( the blood ) ( from ( each atrium ) ) ) ( ( is ( mixed ( in ( the ( single ventricle ) ) ) ) ) ( before ( being ( pumped ( to ( the aorta ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (DT Some) (NNS animals)) (PRN (-LRB- -LRB-) (NP (NP (NNS amphibians)) (CC and) (NP (NNS reptiles))) (-RRB- -RRB-))) (VP (VBP have) (NP (NP (DT a) (JJ three-chambered) (NN heart)) (, ,) (SBAR (WHPP (IN in) (WHNP (WDT which))) (S (NP (NP (DT the) (NN blood)) (PP (IN from) (NP (DT each) (NN atrium)))) (VP (VBZ is) (ADJP (JJ mixed) (PP (IN in) (NP (DT the) (JJ single) (NN ventricle)))) (PP (IN before) (S (VP (VBG being) (VP (VBN pumped) (PP (TO to) (NP (DT the) (NN aorta)))))))))))) (. .)))
Some animals (amphibians and reptiles) have a three-chambered heart, in which the blood from each atrium is mixed in the single ventricle before being pumped to the aorta.
(ROOT (S (NP (EX There)) (VP (VBP are) (NP (NP (CD three) (NNS chambers)) (PP (IN in) (NP (DT an) (NN amphibian) (NN heart))))) (. .)))