answersLogoWhite

0

Excretion is the removal of a substance formed as a waste product of a metabolic pathway form an organism. It is for this reason the the respiratory system (removing CO2) and the urinary system (removing wasted like urea) are excretory systems whilst the GI tract is not (only allows the passage of unwanted food substnaces out and does not add waste products to it).

User Avatar

Wiki User

16y ago

What else can I help you with?