Answer:
1. The overall chemical equation of the light-dependent reactions is given below:
12 H₂O + 12 NADP+ + 18 ADP + 18 Pi + light and chlorophyll ----> 6 O₂ + 12 NADPH + 18 ATP
2. The overall chemical equation for the light-independent reactions of the Calvin cycle is given below :
3 CO₂+ 6 NADPH + 5 H₂O + 9 ATP → glyceraldehyde-3-phosphate (G3P) + 2 H+ + 6 NADP+ + 9 ADP + 8 Pi
Explanation:
1. The light-dependent reactions convert light energy into chemical energy, producing ATP and NADPH which are used light-independent reactions to drive the synthesis of sugar molecules from inorganic CO₂ and water. Light-dependent reactions takes place in photosystem I and II. Photosystem I and Photosystem II ( PS I and PS II) are the two biochemical systems, active in chloroplasts, that serve as sites of electron transfer reactions in photosynthesis. Energy from sunlight is used to split water which releases electrons and hydrogen atoms which are transferred to NADP+ to produce ATP and NADPH and oxygen is produced as a waste product.
The overall chemical equation of the light-dependent reactions is given below:
12 H₂O + 12 NADP+ + 18 ADP + 18 Pi + light and chlorophyll ----> 6 O₂ + 12 NADPH + 18 ATP. Note that Pi refers to inorganic phosphate
2. The Calvin cycle refers to the light-independent reactions in photosynthesis. It occurs in three stages.
Stage 1 (Carbon fixation): In this first stage of the Calvin cycle, light-independent CO₂ is fixed by enzyme called ribulose bisphosphate carboxylase (RuBisCO) to ribulose bisphosphate (RuBP) to form glyceraldehyde-3-phosphate.
Stage2: ATP and NADPH are used to reduce 3-phosphoglycerate (3-PGA) into glyceraldehyde--phosphate (G3P). ATP and NADPH are used up in the process and are converted to ADP and NADP+, respectively.
Third stage: RuBP is regenerated, which enables the system to prepare for more CO2 to be fixed.
The overall chemical equation for the light-independent reactions of the Calvin cycle is given below :
3 CO₂+ 6 NADPH + 5 H₂O + 9 ATP → glyceraldehyde-3-phosphate (G3P) + 2 H+ + 6 NADP+ + 9 ADP + 8 Pi
