The biosphere is the largest ecosystem, consisting of planet Earth and all living things inhabiting it. Within ecosystems, producers like plants generate food from sunlight, water and minerals, consumers eat other organisms, and decomposers break down dead plants and animals, returning minerals to the soil. Food chains show how species are connected through predator-prey relationships, while food webs combine multiple food chains. Human activities like climate change, pollution, overexploitation of resources and habitat alteration are responsible for most recent biodiversity loss through species extinction. National parks and biosphere reserves aim to protect endangered wildlife and environments.