This document discusses energy flow through ecosystems. It begins with energy from the sun being converted to glucose through photosynthesis in producers like plants. Producers use some of this energy but pass the rest to primary consumers like herbivores. Primary consumers pass some energy to secondary consumers like carnivores. This transfer of energy from producers to primary and secondary consumers can be represented through food chains and energy pyramids, with less energy being available at each higher level. Food webs show the complex and interconnected feeding relationships between different organisms in an ecosystem.