Assertion: chloroplast's structure | /r/MadeOf | a calcium ion
Facets:
Source sentences:
text: The oxidation of water is catalyzed in photosystem II by a redox-active structure that contains four manganese ions and a calcium ion; this oxygen-evolving complex binds two water molecules and contains the four oxidizing equivalents that are used to drive the water-oxidizing reaction (Dolai's S-state diagrams).