( ( In ( some algae ) ) ( , ( ( ( ( ( ( the ( haploid gametophyte ) ) ( is multicellular ) ) , ) and ) ( ( when ( gametes ( are ( produced ( -LRB- ( ( by mitosis ) -RRB- ) ) ) ) ) ) ( , ( they ( fuse ( to ( form ( a ( diploid ZYGOTE ) ) ) ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN In) (NP (DT some) (NN algae))) (, ,) (S (NP (DT the) (JJ haploid) (NN gametophyte)) (VP (VBZ is) (ADJP (JJ multicellular)))) (, ,) (CC and) (S (SBAR (WHADVP (WRB when)) (S (NP (NNS gametes)) (VP (VBP are) (VP (VBN produced) (PRN (-LRB- -LRB-) (PP (IN by) (NP (NNS mitosis))) (-RRB- -RRB-)))))) (, ,) (NP (PRP they)) (VP (VBZ fuse) (S (VP (TO to) (VP (VB form) (NP (DT a) (JJ diploid) (NN ZYGOTE))))))) (. .)))
In some algae, the haploid gametophyte is multicellular, and when gametes are produced (by mitosis), they fuse to form a diploid ZYGOTE.
(ROOT (S (NP (DT The) (JJ haploid) (NN gametophyte)) (VP (VBZ produces) (NP (NNS gametes)) (PP (IN through) (NP (NNS mitosis)))) (. .)))