- Sunlight provides energy for most life on Earth through the process of photosynthesis, where plants, algae, and some bacteria use carbon dioxide, water, and sunlight to produce sugar and oxygen. - Producers are organisms that convert sunlight into chemical energy through photosynthesis. Consumers eat other organisms for energy and include herbivores, carnivores, and omnivores. Decomposers and detritivores break down dead organic matter. - Cellular respiration is the process where cells use sugar and oxygen to produce energy, carbon dioxide, and water. Energy transfers between organisms as they eat each other in food chains and food webs.