( So ( , ( ( the sun ) ( ( is ( ( the ( ultimate source ) ) ( of ( energy ( for ( ( most living ) organisms ) ) ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB So)) (, ,) (NP (DT the) (NN sun)) (VP (VBZ is) (NP (NP (DT the) (JJ ultimate) (NN source)) (PP (IN of) (NP (NP (NN energy)) (PP (IN for) (NP (ADJP (RBS most) (JJ living)) (NNS organisms))))))) (. .)))
So, the sun is the ultimate source of energy for most living organisms.
(ROOT (S (ADVP (RB Ultimately)) (, ,) (NP (JJS most) (NN life) (NNS forms)) (VP (VBP get) (NP (PRP$ their) (NN energy)) (PP (IN from) (NP (DT the) (NN sun)))) (. .)))