The primary means of food energy production in most ecosystems is through photosynthesis. In this process, autotrophic organisms like plants, algae, and some bacteria convert sunlight into chemical energy. They absorb light using chlorophyll, transforming carbon dioxide and water into glucose and oxygen. This chemical energy not only fuels the producers themselves but also forms the foundation for the entire food chain, providing energy for herbivores and, subsequently, carnivores and decomposers within the ecosystem.