Biodiversity refers to the variety of living things found in different environments like mountains, water, and as microorganisms. Scientists have studied this variety over long periods. The environment consists of interconnected living and nonliving things like sunlight, air, water, soil, plants, and animals. There are many food chains in nature, with producers like plants using sunlight to make food, which is then eaten by herbivores, and subsequently carnivores, with each organism fulfilling a link. Multiple overlapping food chains make up a food web. Plants play a key role in nature by using sunlight, water and air to produce food that animals then eat. Decomposition of plant and animal residues by microorganisms returns nutrients to the soil