Every organism in the biosphere plays important role in the environment and interacts with various physical and biotic factors, individually or collectively, hence an interacting system is formed in the environment. Ecology is the study of the relationship of plants and animals to their physical and biological environment. The physical environment includes light and heat or solar radiation, moisture, wind, oxygen, carbon dioxide, nutrients in soil, water, and atmosphere. The biological environment includes organisms of the same kind as well as other plants and animals.