Question

Which of the following sequences correctly represents the flow of electrons during photosynthesis? Which of the following sequences correctly represents the flow of electrons during photosynthesis? NADPH → chlorophyll → Calvin cycle H2O → NADPH → Calvin cycle H2O → photosystem I → photosystem II NADPH → O2 → CO2 NADPH → electron transport chain → O2

Answer 1

H2O → NADPH → Calvin cycle

Step-by-step explanation:

During light-dependent reactions of photosynthesis, the water molecule serves as the ultimate electron donor. Splitting of water in presence of sunlight releases electrons which are channeled to the reaction center of PS II to electron transport chain and finally to NADP reductase via PS I. NADP reductase reduces NADP into NADPH.

Therefore, electrons released during the splitting of water are used in the reduction of NADP into NADPH. The NADPH is released in the stroma of chloroplasts where redox reactions of the Calvin cycle occur. NADPH serves as an electron donor for the reduction reactions of the Calvin cycle.