What is implied about the energy requirements of photosystems I and II by the fact that there is a difference in the minimum wavelength of light needed for them to operate $(700\mathrm{nm}\text{ for photosystem }\mathrm{I}\text{ and }680\mathrm{nm}$ for photosystem II )

Step by Step Solution: Step 1. Photosystems I and II are protein complexes found in the thylakoid membrane of chloroplasts that are involved in the light-dependent reactions of photosynthesis. Step 2. Photosystem I (PSI) has a reaction center chlorophyll a molecule that absorbs light at a wavelength of 700 nm while photosystem II (PSII) has a reaction center chlorophyll a molecule that absorbs light at a wavelength of 680 nm. Step 3. The difference in the minimum wavelength of light needed for PS I and PS II to operate suggested that they work together to a generate a range of energy that is needed to efficiently drive the process of photosynthesis. Step 4. PSII, which requires shorter wavelength light at 680 nm, functions first and passes the excited electrons to PSI. PSI requires longer wavelength light at 700nm and re-energizes the electrons it receives from PSII with this wavelength of light. Step 5. Therefore, the difference in the minimum wavelength of light needed for PS I and PS II to operate suggests that both photosystems work together in a complementary fashion to drive the process of photosynthesis.