( ( Active transport ) ( ( ( requires energy ) ( to ( ( move solute ) ( against ( ( ( an electrochemical ) or ) ( a ( concentration gradient ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Active) (NN transport)) (VP (VBZ requires) (NP (NN energy)) (S (VP (TO to) (VP (VB move) (NP (NN solute)) (PP (IN against) (NP (NP (DT an) (NN electrochemical)) (CC or) (NP (DT a) (NN concentration) (NN gradient)))))))) (. .)))
Active transport requires energy to move solute against an electrochemical or a concentration gradient.
(ROOT (S (NP (NNP Passive) (NN transport)) (VP (VP (VBZ requires) (NP (DT no) (NN energy))) (CC and) (VP (VBZ occurs) (SBAR (WHADVP (WRB when)) (S (NP (NNS substances)) (VP (VBP move) (PP (IN from) (NP (NP (NNS areas)) (PP (IN of) (NP (NP (JJR higher)) (PP (TO to) (NP (JJR lower) (NN concentration)))))))))))) (. .)))