Chloroplast fragments without P700 were studied to understand Photosystem II activity. These fragments had chlorophyll a/b ratios of 1.7–1.9 and lacked P700, cytochrome f, and cytochrome b6. They couldn't reduce NADP+ with ascorbate and 2,6-dichlorophenolindophenol. However, they could perform electron-transfer reactions with water or diphenylcarbazide, sensitive to DCMU. They could also reduce NADP+ with ascorbate and plastocyanin, unaffected by DCMU, and more effective with 664-nm light than 715-nm light. These results suggest two Photosystem II reactions work together in electron transport.