All living things need some things in order to survive. Some of those things are supplied by other living things, and some are supplied by nonliving things. The interaction between living and nonliving in an area creates an ecosystem. The living elements of an ecosystem are water, soil, light and air. Animals, including people, need food, water and oxygen and plants need water, soil, light and air (carbon dioxide). Plants use water, light and carbon dioxide to produce food, called glucose, through the process of photosynthesis. The by-product of photosynthesis is oxygen which is released into the air.