You can think of C3, C4 and CAM as interchangeable functions, yes. They take in CO2 and energy from sunlight, and they output sugar: def photosynthesis(co2,

You can think of C3, C4 and CAM as interchangeable functions, yes. They take in CO2 and energy from sunlight, and they output sugar: def photosynthesis(co2, energy) # C3, C4 or CAM return sugar end to your second question, plants absorb photons that are not converted to biomass because all the light harvesting machinery is saturated. But this is only true at the parts of the plant that are most exposed to light. The idea is that we could reduce the absorption in those parts and let some light through to other parts of the plant, where it could be absorbed at a different wavelength if we install that ability.