Which zone would you expect to find the majority of photosynthetic organisms such as phytoplankton?

Which zone would you expect to find the majority of photosynthetic organisms such as phytoplankton?

• A. Surface zone
• B. Deep zone
• C. Mesopelagic zone
• D. Bathypelagic zone

Answer: (A)

Photosynthesis needs light, so the organisms that perform it—the phytoplankton—live where sunlight can reach. The surface zone is the sunlit layer of the ocean (roughly the upper ~200 meters in clear water), the area where photosynthesis can occur. Deeper zones receive little to no light, making photosynthesis virtually impossible, so far fewer photosynthetic organisms are found there. That’s why the majority of phytoplankton are found in the surface zone.

Photosynthesis needs light, so the organisms that perform it—the phytoplankton—live where sunlight can reach. The surface zone is the sunlit layer of the ocean (roughly the upper ~200 meters in clear water), the area where photosynthesis can occur. Deeper zones receive little to no light, making photosynthesis virtually impossible, so far fewer photosynthetic organisms are found there. That’s why the majority of phytoplankton are found in the surface zone.