Final answer:
The intertidal zone is where organisms are intermittently submerged and exposed due to tides; it's where you'd find species adapted to a mix of wet and dry conditions. Photosynthesis mainly occurs in the intertidal and neritic zones, which are part of the photic zone where sunlight is sufficient.
Step-by-step explanation:
The organisms that are exposed to air and sunlight at low tide, but are underwater most of the time, especially during high tide, inhabit the intertidal zone. This zone is the area that sits between the high and low tide lines. Organisms living here are well-adapted to withstand the changing conditions of moisture, salinity, and temperature due to the tidal rhythms. In the intertidal zone, shore crabs such as Carcinus maenas and barnacles exhibit adaptations like tough exoskeletons to protect themselves from desiccation and wave damage.
When it comes to the location where you would expect to find the most photosynthesis in an ocean biome, the regions are the photic zone, which includes the intertidal and neritic zones, where adequate sunlight enables the process. The aphotic zone, on the other hand, is too deep for sufficient sunlight to penetrate, thus photosynthesis is not prevalent there.