( ( ( ( ( Circadian rhythms ) , ) ( ( ( the patterns ) ( of activity ) ) ( that ( occur ( on ( a ( 24-hour cycle ) ) ) ) ) ) ) , ) ( ( are ( ( important ( biological regulators ) ) ( in ( virtually ( every ( living creature ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NN Circadian) (NNS rhythms)) (, ,) (NP (NP (DT the) (NNS patterns)) (PP (IN of) (NP (NN activity))) (SBAR (WHNP (WDT that)) (S (VP (VBP occur) (PP (IN on) (NP (DT a) (JJ 24-hour) (NN cycle))))))) (, ,)) (VP (VBP are) (NP (NP (JJ important) (JJ biological) (NNS regulators)) (PP (IN in) (NP (RB virtually) (DT every) (JJ living) (NN creature))))) (. .)))
Circadian rhythms, the patterns of activity that occur on a 24-hour cycle, are important biological regulators in virtually every living creature.
(ROOT (S (NP (NP (JJ Regular) (NNS changes)) (PP (IN in) (NP (NN biology) (CC or) (NN behavior))) (SBAR (WHNP (WDT that)) (S (VP (VBP occur) (PP (IN in) (NP (DT a) (CD 24) (NN hour) (NN cycle))))))) (VP (VBP are) (NP (NP (NN part)) (PP (IN of) (NP (DT the) (NN circadian) (NN rhythm))))) (. .)))