AP BIOLOGY

Detailed explanation-1: -The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP+ to the light reactions. The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions. No worries!

Detailed explanation-2: -The Calvin cycle converts ATP to ADP and Pi, and it converts NADPH to NADP+. The ADP, Pi, and NADP+ can be reused as substrates in the light reactions.

Detailed explanation-3: -In the second stage, ATP and NADPH are used to reduce 3-PGA into G3P; then ATP and NADPH are converted to ADP and NADP+, respectively. In the last stage of the Calvin Cycle, RuBP is regenerated, which enables the system to prepare for more CO2 to be fixed.

Detailed explanation-4: -The immediate products of one turn of the Calvin cycle are 2 glyceraldehyde-3-phosphate (G3P) molecules, 3 ADP, and 2 NADP+. (ADP and NADP+ are not really “products". They are regenerated and later used again in the light-dependent reactions).

Detailed explanation-5: -The net effect of these steps is to convert light energy into chemical energy in the form of ATP and NADPH. The ATP and NADPH from the light-dependent reactions are used to make sugars in the next stage of photosynthesis, the Calvin cycle.