( ( ( Explain ( ( the action ) ( of ( ( lysozyme and ) penicillin ) ) ) ) ( on ( the ( bacterial ( cell wall ) ) ) ) ) . )
(ROOT (S (VP (VB Explain) (NP (NP (DT the) (NN action)) (PP (IN of) (NP (NN lysozyme) (CC and) (NN penicillin)))) (PP (IN on) (NP (DT the) (JJ bacterial) (NN cell) (NN wall)))) (. .)))
Explain the action of lysozyme and penicillin on the bacterial cell wall.
(ROOT (S (NP (DT A) (NN lysozyme)) (VP (VBZ destroys) (NP (NNS bacteria)) (PP (IN by) (S (VP (VBG digesting) (NP (PRP$ their) (NN cell) (NNS walls)))))) (. .)))