( Amphibians ( ( ( ( are ectothermic ) , ) ( depending ( upon ( external ( heat ( to ( regulate ( body temperature ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Amphibians)) (VP (VBP are) (ADJP (JJ ectothermic)) (, ,) (PP (VBG depending) (PP (IN upon) (NP (JJ external) (NN heat) (S (VP (TO to) (VP (VB regulate) (NP (NN body) (NN temperature))))))))) (. .)))
Amphibians are ectothermic, depending upon external heat to regulate        body temperature.
(ROOT (S (NP (NNP Ectothermic)) (VP (VBZ is) (NP (NP (DT the) (NN term)) (PP (IN for) (NP (NP (NNS animals)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (RB not) (VP (VB raise) (NP (PRP$ their) (NN body) (NN temperature)) (PP (IN on) (NP (PRP$ their) (JJ own))))))))))) (. .)))