( ( ( ( ( ( The bacterium ) ( s ( ( preferred nutrient ) ( is ( the ( simpler ( sugar glucose ) ) ) ) ) ) ) , ) but ) ( ( when ( glucose ( is scarce ) ) ) ( , ( ( the cell ) ( can ( make ( do ( by ( living ( on lactose ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT The) (NN bacterium)) (VP (VBZ s) (NP (NP (JJ preferred) (NN nutrient)) (SBAR (S (VP (VBZ is) (NP (DT the) (JJR simpler) (NN sugar) (NN glucose)))))))) (, ,) (CC but) (S (SBAR (WHADVP (WRB when)) (S (NP (NN glucose)) (VP (VBZ is) (ADJP (JJ scarce))))) (, ,) (NP (DT the) (NN cell)) (VP (MD can) (VP (VB make) (VP (VB do) (PP (IN by) (S (VP (VBG living) (PP (IN on) (NP (NN lactose)))))))))) (. .)))
The bacterium s preferred nutrient is the simpler sugar glucose, but when glucose is scarce, the cell can make do by living on lactose.
(ROOT (S (NP (NP (NNS Monosaccharides)) (, ,) (ADJP (RB particularly) (JJ glucose)) (, ,)) (VP (VBP are) (NP (NP (JJ major) (NNS nutrients)) (PP (IN for) (NP (NNS cells))))) (. .)))