Energy flows through an ecosystem in a circular pattern starting with plants, which grow by photosynthesis and taking water and minerals from the ground. They are then eaten by herbivores, which are, in turn, consumed by carnivores.
Omnivores eat both the plants and the other animals.
Once a creature dies, bacteria breaks down and decomposes the animal and turns it into minerals and nutrients for plants to consume. When respiration occurs, the carbon-carbon bonds are broken and the carbon is combined with oxygen to form carbon dioxide. This process releases energy by the organism or it is lost as heat. They are nutrients that do not contain carbon-carbon bonds. The ultimate fate of energy in ecosystems is for it to be lost as heat.