Hello, this question is incomplete. The complete question would be:
"How Light and Dark Photosynthesis Reactions Work Together"
Answer:
In short, the light reaction of photosynthesis provides ATP and NADPH for the dark reaction to form glucose.
Step-by-step explanation:
Photosynthesis is divided into two reactions the light phase and the dark phase. In short, the light reaction of photosynthesis provides ATP and NADPH for the dark reaction to form glucose.
The clear reaction occurs in membrane structures. In chloroplasts, it occurs in thylakoids, which present chlorophyll. In cyanobacteria the clear phase occurs in the plasma membrane. This is because in these membranes there are substances called cytochromes, which participate in the process through an electron transport chain. In this reaction, photophosphorylation occurs, that is, the production of ATP (ADP phosphorylation) with the participation of light (hence the name, photophosphorylation). The light stimulates chlorophyll, which releases electrons to a cytochrome transporter chain on the tilacoid membrane. Electron transfer between cytochromes is linked to ATP synthesis. The electrons may return to chlorophyll (cyclic photophosphorylation) or not (acyclic photophosphorylation).
In acyclic photophosphorylation, electrons transferred by chlorophyll do not return to this pigment and are captured by NADP. The water is broken which supplies electrons to the chlorophyll, releases oxygen gas and two protons, which will be captured by the NADP. Thus, acyclic photophosphorylation produces ATP (by the electron transport chain) and NADPH.
Thus, the light phase produces, in addition to oxygen, NADPH and ATP, and these two will be reactants in the next phase, the dark phase.
In the "dark" reaction, carbon dioxide is reduced to glucose, the endothermic process, in a process called the Calvin-Benson Cycle. The reducing agent is NADPH which transfers electrons to the cycle while ATP supplies energy to the process. Glucose is the product of the Calvin cycle.