1)The nitrogen compounds through which excess nitrogen is eliminated from organisms are called nitrogenous wastes (/naɪˈtrɒdʒɪnəs/) or nitrogen wastes. They are AMMONIA, urea, uric acid, and creatinine. All of these substances are produced from protein metabolism.2)The two most important bile pigments are bilirubin, which is orange or yellow, and its oxidized form biliverdin, which is green. Mixed with the intestinal contents, they give the brown colour to the faeces (see urobilinogen).3)Excretory systems regulate the chemical composition of body fluids by removing metabolic wastes and retaining the proper amounts of water, salts, and nutrients. Components of this system in vertebrates include the kidneys, liver, lungs, and skin.4)In addition to the urinary system, the skin, lungs and liver of vertebrates are accessory excretory organs. (1) Skin: Human skin possesses glands for secreting two fluids on its surface, namely sweat from the sweat glands and sebum from sebaceous glands.5)A vitamin that can dissolve in water. Water-soluble VITAMINS are carried to the body's tissues but are not stored in the body. They are found in plant and animal foods or dietary SUPPLEMENTS and must be taken in daily. Vitamin C and members of the vitamin B complex are water-soluble.I hope it will be helpful to you friend