Question

what extra ingredient does the Calvin Cycle need that was not needed in light dependent reactions?

Answer 1

So the calvin cycle needs CO2 to function. This is not found in the light-dependent reaction.

Answer 2

This is because during the light-dependent reactions, plants breaks down water and essentially uses one of its protons and electrons to create energy. This energy then uses CO2 in the light-independent reaction to create glucose (a sugar stored within the plant, which also contains energy).