Hint:Substances leftover from metabolic processes (such as cellular respiration) that can not be utilised by the organism (they are surplus or toxic) and must therefore be excreted are metabolic waste or excrement.
Complete Answer: Nitrogen compounds, water, $CO_2$, phosphates, sulphates, etc. are included. These compounds are handled as excrement by animals. Plants have chemical "machinery" that converts some of them into useful substances (primarily nitrogen compounds).All metabolic waste is excreted through the excretory organs in the form of water solutes (nephridia, malpighian tubules, kidney), with the exception of $CO_2$, which is excreted in the lungs along with water vapour. The elimination of these compounds helps the body to undergo chemical homeostasis. The excretion of excess nitrogen in the form of uric acid is uricotelism. Insects, birds and most reptiles contain uricotelic animals. While it takes more metabolic energy to manufacture than urea, the low toxicity and low water solubility of uric acid allow it to be condensed into small amounts of pasty white suspension compared to mammalian liquid urine.
Note:Uricotelic is classified as an animal that excretes its nitrogenous waste predominantly in the form of uric acid and urates. Uricotelism is known as this phenomenon. Uric acid is produced by all terrestrial animals, such as insects, reptiles and birds.