Final answer:
Adding paraquat to a plant decreases the concentrations of ATP, NADPH, and sugars because it disrupts the photosynthesis process, particularly photosystem I, which is crucial for the production of these molecules.
Step-by-step explanation:
When paraquat is added to a plant, it interferes with the photosynthesis process by causing the production of harmful oxygen radicals. This results in a decrease in the efficiency of photosystem I, leading to a reduced production of ATP and NADPH, which are essential for the Calvin cycle to produce sugars.
Therefore, the concentrations of ATP and NADPH will decrease, and because these molecules are essential in synthesizing sugars through the Calvin cycle, sugar concentrations will also decrease.