( ( If ( ( the ( electron acceptor ) ) ( ( is not ) O2 ) ) ) ( ( the process ) ( ( is ( called ( anaerobic respiration ) ) ) . ) ) )
(ROOT (S (SBAR (IN If) (S (NP (DT the) (NN electron) (NN acceptor)) (VP (VBZ is) (RB not) (NP (NNP O2))))) (NP (DT the) (NN process)) (VP (VBZ is) (VP (VBN called) (NP (JJ anaerobic) (NN respiration)))) (. .)))
If the electron acceptor is not O2 the process is called anaerobic respiration.
(ROOT (S (NP (PRP You)) (VP (VBP call) (NP (NP (NNS prokaryotes)) (SBAR (WHNP (WDT that)) (S (VP (VBP do) (RB not) (VP (VB need) (NP (NN oxygen)) (PP (IN for) (NP (NN respiration) (NN anaerobic))))))))) (. .)))