Final answer:
The isolated chloroplasts in the dark with an acidic interior transferred to a pH 8 solution will produce ATP due to an existing proton gradient, but cyclic photophosphorylation and the Calvin cycle will not occur due to the absence of light.
Step-by-step explanation:
If the interior of the thylakoids of isolated chloroplasts were made acidic and then placed in a pH 8 solution in the dark, what would likely happen is the isolated chloroplasts will make ATP. This process occurs because a proton gradient has been established across the thylakoid membrane, and ATP synthase uses this gradient to generate ATP, a phenomenon known as chemiosmosis. The critical detail in the question is that the chloroplasts are placed in darkness, which means there is no light to drive the light-dependent reactions of photosynthesis. Therefore, cyclic photophosphorylation will not occur, as it still depends upon light to generate an initial electron excitation within the photosystems.
Moreover, the Calvin cycle, which is the light-independent reaction, will not be activated because it requires products (ATP and NADPH) from the light-dependent reactions. Since the chloroplasts are in the dark, the necessary light-dependent reactions cannot supply these molecules, and hence, the Calvin cycle will not proceed. This cycle also depends on the presence of carbon dioxide and wouldn't automatically start simply because there is availability of ATP generated in the dark.