What is Excretion? Excretion is the elimination of metabolic wastes and excess materials from the interior of a cell, tissue, or animal body so as to maintain homeostasis. It excludes defaecation which is the egestion or removal of undigested food residue from the digested tract. Excretion is highly important as the accumulation of metabolic wastes and other excess substances can be toxic resulting in discomfort, disorders, and death. Waste materials excreted in animals are of many kinds- nitrogenous substances, carbon-dioxide, pigments, spices, drugs, excess of water, inorganic salts, hormones, and vitamins. These materials are grouped under two categories- CO2 is … Continue reading What is Excretion? Classify the animals on the basis of their excretory products