1. The document discusses energy flow through ecosystems, including trophic levels, producers, consumers, food chains, and energy pyramids. Producers, like plants, use photosynthesis to convert sunlight into chemical energy stored in glucose. 2. Consumers that eat producers are primary consumers, while those that eat other consumers are secondary or tertiary consumers. Much of the energy is lost at each trophic level, following the 10% rule. 3. Food chains show the transfer of energy between organisms, while food webs show complex interconnected feeding relationships within an ecosystem. Energy pyramids illustrate how available energy decreases with each trophic level.