( ( ( ( The role ) ( of ( electron carriers ) ) ) ( in ( aerobic respiration ) ) ) . )
(ROOT (NP (NP (DT The) (NN role)) (PP (IN of) (NP (NN electron) (NNS carriers))) (PP (IN in) (NP (JJ aerobic) (NN respiration))) (. .)))
The role of electron carriers in aerobic respiration.
(ROOT (S (NP (NP (DT The) (NN structure)) (PP (IN of) (NP (NN mitochondrion)))) (VP (VBZ plays) (NP (NP (DT an) (JJ important) (NN role)) (PP (IN in) (NP (JJ aerobic) (NN respiration))))) (. .)))