They lay eggs because they don't have the genetics or things in their body to give birth.
Http://www.phschool.com/science/biology_place/biocoach/bioprop/folding.html hope it helpps
The light reactions produce ATP and NADPH thet the Calvin cycle uses to convert CO2 into carbohydrate. The light reactions in the thylakoid membranes of the chloroplast, and the reactions of the Calvin cycle take place in the stroma