( ( ( ( Gametes , ) ( ( ( the sperm ) and ) eggs ) ) , ) ( ( are ( produced ( by ( mitosis ( in ( the ( haploid gametophyte ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Gametes)) (, ,) (NP (NP (DT the) (NN sperm)) (CC and) (NP (NNS eggs))) (, ,)) (VP (VBP are) (VP (VBN produced) (PP (IN by) (NP (NP (NNS mitosis)) (PP (IN in) (NP (DT the) (JJ haploid) (NN gametophyte))))))) (. .)))
Gametes, the sperm and eggs, are produced by mitosis in the haploid  gametophyte.
(ROOT (S (NP (DT The) (JJ haploid) (NN gametophyte)) (VP (VBZ produces) (NP (NNS gametes)) (PP (IN through) (NP (NNS mitosis)))) (. .)))