If the calvin cycle slows down, what will happen to the rate of o2 production in ps ii, and why? if the calvin cycle slows down, what will happen to the rate of o2 production in ps ii, and why? o2 production will not change because the calvin cycle is a separate process from the light reactions. o2 production will speed up because not as much nadph will be used in the calvin cycle and so it will accumulate in the chloroplast. o2 production will slow down because the chloroplast will need less light energy to send to the calvin cycle. o2 production will slow down because less nadp+ will be regenerated in the calvin cycle. o2 production will not change because light energy will still be absorbed by the pigment molecules and excite the ps ii chlorophyll a pair.