( Life ( ( begins ( at ( ( 12 weeks ) ( when ( ( the fetus ) ( develops ( a ( functional heartbeat ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Life)) (VP (VBZ begins) (PP (IN at) (NP (NP (CD 12) (NNS weeks)) (SBAR (WHADVP (WRB when)) (S (NP (DT the) (NN fetus)) (VP (VBZ develops) (NP (DT a) (ADJP (JJ functional)) (NN heartbeat)))))))) (. .)))
Life begins at 12 weeks when the fetus develops a functional heartbeat.
(ROOT (S (NP (NP (DT The) (NN development)) (PP (IN of) (NP (NP (DT the) (JJ respiratory) (NN system)) (PP (IN in) (NP (DT the) (NN fetus)))))) (VP (VBZ begins) (PP (IN at) (NP (QP (RB about) (CD 4)) (NNS weeks)))) (. .)))
The development of the respiratory system in the fetus begins at about 4 weeks.