In smaller organisms there are different ways of excretion of waste materials. 

This depends on the arrangement of the body of the organism.


  • In unicellular organisms like amoeba, wastes (like CO 2 ) are let out directly by diffusion from the body. Nitrogenous wastes like ammonia and water are removed by the contractile vacuole .

  • In multicellular organism like fishes or birds, nitrogenous wastes are of different types : 
  • In Earthworms , tubular structures called nephridia are the excretory organs. It’s moist skin also expels CO 2
  • Fishes have ammonia as their waste product
  • Birds excrete waste in the form of uric acid
  • Human beings have urea as their nitrogenous waste 

  1. Class 10
  2. Chapter 6 Class 10 - Life Processes (Term 1)

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo