( ( ( ( B -RRB- ) ( ( active transport ) ( of molecules ) ) ) ( against ( their ( concentration gradients ) ) ) ) . )
(ROOT (S (VP (VBD B) (-RRB- -RRB-) (NP (NP (JJ active) (NN transport)) (PP (IN of) (NP (NNS molecules)))) (PP (IN against) (NP (PRP$ their) (NN concentration) (NNS gradients)))) (. .)))
B) active transport of molecules against their concentration gradients.
(ROOT (S (NP (JJ Primary) (JJ active) (NN transport)) (VP (VBZ involves) (NP (NP (DT the) (NN forcing)) (PP (IN of) (NP (DT a) (NN substance)))) (PP (IN into) (NP (NP (DT a) (NN cell)) (PP (IN against) (NP (PRP$ its) (NN concentration) (NN gradient)))))) (. .)))