Major objective of this lecture is to present on Feeding Relationships. Ecology is the study of living organisms in their environment. An ecosystem is a distinct area within earth’s environment and it includes organisms living there and interacting with one another as well as with the background non-living parts of the environment. The ultimate source of energy for most living organisms is the sun. Green plants are able to trap energy from the sun and use it to convert carbon dioxide and water into food energy in the form of sugar in a process known as photosynthesis.