( ( Renal excretion ) ( ( occurs ( by ( ( ( glomerular filtration ) and ) ( active ( tubular secretion ) ) ) ) ) . ) )
(ROOT (S (NP (JJ Renal) (NN excretion)) (VP (VBZ occurs) (PP (IN by) (NP (NP (NN glomerular) (NN filtration)) (CC and) (NP (JJ active) (JJ tubular) (NN secretion))))) (. .)))
Renal excretion occurs by glomerular filtration and active tubular secretion.
(ROOT (S (NP (NP (DT The) (JJ main) (NNS functions)) (PP (IN of) (NP (NN epithelia)))) (VP (VBP are) (NP (NP (NN protection)) (PP (IN from) (NP (NP (DT the) (NN environment) (, ,) (NN coverage) (, ,) (NN secretion) (CC and) (NN excretion)) (, ,) (NP (NN absorption)) (, ,) (CC and) (NP (NN filtration)))))) (. .)))