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O LevelBiologyCambridge (CIE)Revision Notes13. Excretion in Humans13.1 ExcretionExcretion of Carbon Dioxide & Urea

Excretion of Carbon Dioxide & Urea (Cambridge (CIE) O Level Biology) : Revision Note

Lára Marie McIvor

Written by: Lára Marie McIvor

Reviewed by: Lucy Kirkham

Updated on

Excretion of Carbon Dioxide & Urea

  • Excretion can be defined as follows:

The removal of the waste products of metabolism and other toxic material from the body

  • Waste products of metabolism include:

    • Carbon dioxide

      • This is a waste product of respiration and is excreted via the lungs

    • Urea

      • Urea is produced in the liver during the breakdown of excess amino acids and is excreted via the kidneys

 Organs involved in excretion of urea and CO2 diagram

Organs involved in excretion

The lungs, liver and kidneys are involved in excretion

Examiner Tips and Tricks

Remember that waste products have to be excreted because they are toxic in some way. Allowing a buildup of toxic products would lead to cell damage and eventually organ failure and death. 

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    Author
    Reviewer
    Lára Marie McIvor

    Author: Lára Marie McIvor

    Expertise: Biology Lead

    Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

    Lucy Kirkham

    Reviewer: Lucy Kirkham

    Expertise: Head of STEM

    Lucy has been a passionate Maths teacher for over 12 years, teaching maths across the UK and abroad helping to engage, interest and develop confidence in the subject at all levels.Working as a Head of Department and then Director of Maths, Lucy has advised schools and academy trusts in both Scotland and the East Midlands, where her role was to support and coach teachers to improve Maths teaching for all.