Carbon dioxide is an end product of cellular respiration in organisms that obtain energy by breaking down sugars, fats and amino acids with oxygen as part of their metabolism. This includes all plants, algae and animals and aerobic fungi and bacteria.arbon dioxide (CO 2) is a product of respiration of all aerobic organisms. It is returned to water via the gills of fish and to the air via the lungs of air-breathing land animals, including humans.