Photosynthesis is used by what organisms to provide food for zooplankton?

Phytoplankton are the correct answer because they are microscopic, photosynthetic organisms found in aquatic environments. These organisms utilize sunlight to convert carbon dioxide and water into glucose and oxygen through the process of photosynthesis. This production of organic matter serves as the primary food source for many aquatic organisms, including zooplankton, which are small, drifting animals in water that feed on phytoplankton.

Phytoplankton form the base of the aquatic food web, providing essential energy and nutrients that support a wide variety of aquatic life. Zooplankton consume phytoplankton, thereby transferring the energy captured during photosynthesis to higher trophic levels within the food web. This relationship emphasizes the crucial role that phytoplankton play in maintaining the health and balance of aquatic ecosystems.