( Heterotrophs ( ( are ( ( all organisms ) ( that ( ( obtain ( their food ) ) ( from ( the environment ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Heterotrophs)) (VP (VBP are) (NP (NP (DT all) (NNS organisms)) (SBAR (WHNP (WDT that)) (S (VP (VBP obtain) (NP (PRP$ their) (NN food)) (PP (IN from) (NP (DT the) (NN environment)))))))) (. .)))
Heterotrophs are all organisms that obtain their food from the environment.
(ROOT (S (SBAR (IN Because) (S (NP (DT all) (NNS animals)) (VP (VBP require) (NP (NP (DT an) (JJ external) (NN source)) (PP (IN of) (NP (NN food))))))) (, ,) (NP (PRP they)) (VP (VBP are) (VP (VBN called) (S (ADJP (JJ heterotrophic))))) (. .)))