A primary producer in photosynthesis is typically a plant, algae, or cyanobacteria that converts sunlight into chemical energy. These organisms use chlorophyll to capture light energy and convert carbon dioxide and water into glucose and oxygen. Through this process, they play a fundamental role in the food web, serving as the basis for energy flow in ecosystems. As primary producers, they not only support their growth but also provide energy and nutrients for higher trophic levels, demonstrating their key importance in maintaining ecological balance.