What could sources of error be in an experiment where the aim is to investigate the effect of light and CO2 on photosynthesis of pelargonium (geranium) as measured by intensity of starch production?

Question

anonymous · Answer

well photosynthesis makes glucose not starch, so that might be the problem

anonymous · Answer

Thank you for your answer.
I know that, but in this experiment we investigated the factors that affect photosynthesis, measured by the presence of starch. If we remove one of the factors of photosynthesis, for an example light, there would be no photosynthesis --> no starch?