( ( During ( sexual reproduction ) ) ( , ( ( a sperm ) ( ( fertilizes ( ( an ( egg ( ( cell or ) ovum ) ) ) ( to ( form ( a zygote ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN During) (NP (JJ sexual) (NN reproduction))) (, ,) (NP (DT a) (NN sperm)) (VP (VBZ fertilizes) (S (NP (DT an) (NN egg) (NN cell) (CC or) (NN ovum)) (VP (TO to) (VP (VB form) (NP (DT a) (NN zygote)))))) (. .)))
During sexual reproduction, a sperm fertilizes an egg cell or ovum to form a zygote .
(ROOT (S (NP (NP (DT The) (VBN fertilized) (NN egg)) (SBAR (WHNP (WDT that)) (S (ADVP (RB sexually)) (VP (VBG reproducing) (S (NP (NNS organisms)) (VP (VB begin) (NP (NN life)) (SBAR (IN as) (S (VP (VBZ is) (VP (VBN known) (PP (IN as) (NP (DT a) (-LRB- -LRB-) (NN n) (-RRB- -RRB-))))))))))))) (VP (VBP zygote)) (. .)))