( Trichomoniasis ( ( is ( caused ( by ( ( ( ( ( a ( single-celled organism ) ) , ) ( a protozoan ) ) , ) ( that ( is ( ( much larger ) ( than ( a bacteria ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Trichomoniasis)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NP (DT a) (JJ single-celled) (NN organism)) (, ,) (NP (DT a) (NN protozoan)) (, ,) (SBAR (WHNP (WDT that)) (S (VP (VBZ is) (ADJP (ADJP (RB much) (JJR larger)) (PP (IN than) (NP (DT a) (NNS bacteria))))))))))) (. .)))
Trichomoniasis is caused by a single-celled organism, a protozoan, that is much larger than a bacteria.
(ROOT (S (NP (NNS Trichomoniasis)) (VP (VBZ is) (VP (VB cause) (PP (IN by) (NP (DT a) (NN protozoa))))) (. .)))