Why is the dark stage given the alternative name of the light-independent stage?

Why is the dark stage given the alternative name of the light-independent stage?

• A. Light dependent
• B. It occurs only at night
• C. It uses oxygen
• D. Light not required

Answer: (C)

The main idea is that this stage does not require light directly to run. In the Calvin cycle, plants take in carbon dioxide and build sugars, using energy in the form of ATP and the reducing power of NADPH that were generated by the light reactions. The reactions happen in the chloroplast stroma and can proceed in light or dark, as long as those energy carriers are available. Oxygen isn’t used in this stage—the oxygen you see coming from photosynthesis comes from the light-dependent reactions that split water. So the reason this stage is called light-independent is that photons aren’t directly driving its chemistry; the energy comes from ATP and NADPH produced earlier.

The main idea is that this stage does not require light directly to run. In the Calvin cycle, plants take in carbon dioxide and build sugars, using energy in the form of ATP and the reducing power of NADPH that were generated by the light reactions. The reactions happen in the chloroplast stroma and can proceed in light or dark, as long as those energy carriers are available. Oxygen isn’t used in this stage—the oxygen you see coming from photosynthesis comes from the light-dependent reactions that split water. So the reason this stage is called light-independent is that photons aren’t directly driving its chemistry; the energy comes from ATP and NADPH produced earlier.