Answer;
1. In the light reactions, light energy is used to oxidize H2O to O2.
2. The electrons derived from this oxidation reaction in the light reactions are used to reduce NADP+ to NADPH.
3. The Calvin cycle oxidizes the light-reactions product NADPH to NADP+.
4. The electrons derived from this oxidation reaction in the Calvin cycle are used to reduce CO2 to G3P.
Explanation;
- In the light reactions, light energy is used to remove electrons from (oxidize) water, producing O2 gas. These electrons are ultimately used to reduce NADP+ to NADPH.
- In the Calvin cycle, NADPH is oxidized back to NADP+ (which returns to the light reactions). The electrons released by the oxidation of NADPH are used to reduce three molecules of CO2 to sugar (G3P), which then exits the Calvin cycle.
- As ATP and NADPH are used in the Clavin cycle, they produce ADP and NADP+, respectively, which are returned to the light reactions so that more ATP and NADPH can be formed.