Final answer:
If Photosystem II stops working, ATP and NADPH production decreases and as a result, the synthesis of sugars in the Calvin cycle is slowed down, leading to a decrease in sugar production as well.
Step-by-step explanation:
If a part of photosynthesis stops working, specifically Photosystem II (PS2), the production of ATP and NADPH would be affected, resulting in a subsequent impact on sugar synthesis. During the light-dependent reactions of photosynthesis, PS2 plays a crucial role in splitting water to generate electrons, which contribute to the production of ATP and NADPH. If PS2 is not functioning, electrons wouldn't be provided to the electron transport chain, leading to a decrease in the production of ATP and NADPH.
Since both ATP and NADPH are utilized in the Calvin cycle for fixing carbon dioxide (CO2) into sugars, a reduction in their availability would slow down the Calvin cycle as well. This would lead to a decrease in sugar production because less CO2 would be fixed into organic molecules. Hence, the correct answer would be:
AT: Down, NADPH: Down, Sugar: Down