Difference between light and dark photosynthesis reactions?

Question

I've been wondering what the differences in the physical and chemical reactions of photosynthesis when exposed to light, and when in the dark are. Can you help me? Thanks!

Answer 1

The light and dark reactions both really need light to occur.

In the light reactions, sunlight splits H2O to produce H+ (for energy) and O2 (waste).  The end products are NADPH and ATP, which are both energy sources that drive the dark reactions.

The dark reactions don't need sunlight directly, but use the energy produced during the light reactions.  Here, CO2 is fixed from the air and converted into starches and sugars using NADPH and ATP to power the conversion.