Metabolic Waste
Metabolic wastes or excretes are substances left over from excretory processes, which cannot be used by the organism (they are surplus or have lethal effect), and must therefore be excreted. This includes nitrogen compounds, water, CO2, phosphates, sulfates, etc. Animals treat these compounds as excretes. Plants have chemical "machinery" which transforms some of them (primarily the nitrogen compounds) into useful substances, and it has been shown by Brian J. Ford that abscissa leaves also carry wastes away from the parent plant. In this way, Ford argues that the shed leaf acts as an excretory (an organ carrying away excretory products).
All the metabolic wastes are excreted in a form of water solutes through the excretory organs (nephridia, Malpighian tubules, kidneys), with the exception of CO2, which is excreted together with the water vapor throughout the lungs. The elimination of these compounds enables the chemical homeostasis of the organism.
Read more about Metabolic Waste: Nitrogen Wastes, Water and Gases, Solids
Famous quotes containing the word waste:
“For them it’s out-of-date and outmoded to perform miracles; teaching the people is too like hard work, interpreting the holy scriptures is for schoolmen and praying is a waste of time; to shed tears is weak and womanish, to be needy is degrading; to suffer defeat is a disgrace and hardly fitting for one who scarcely permits the greatest of kings to kiss the toes of his sacred feet; and finally, death is an unattractive prospect, and dying on a cross would be an ignominious end.”
—Desiderius Erasmus (c. 1466–1536)