The FORMATION and EXCRETION of UREA (CIE IGCSE Biology CORE & SUPPLEMENT)

This detailed and engaging lesson focuses on the importance of the excretion of carbon dioxide and urea in humans. It also looks at how the urea is formed as a result of deamination in the liver and as such covers the Core and Supplement content of the early section of topic 13 of the CIE IGCSE Biology specification.

The lesson begins with a “Crack the code” type task which will enable the students to learn the meaning of excretion and specifically how it relates to the products of metabolism. Excretion is often confused with egestion by students so this misconception is addressed immediately and as a result they will understand that carbon dioxide and urea have to be excreted whereas faeces is egested. Moving forwards, time is taken to explain why carbon dioxide needs to be excreted and links are made to the earlier topic of enzymes and how a fall in pH could affect their activity. The rest of the lesson focuses on the formation of urea in the liver. Whilst learning about deamination, students will also be introduced to the process of assimilation and the production of rge plasma protein fibrinogen is used to explain the importance of this function of the liver. In addition to understanding checks and prior knowledge checks, quiz competitions are included in the lesson to introduce key terms in a fun and memorable way.

This lesson has been designed for students studying the CIE IGCSE Biology course but is also suitable for older students who are starting the topic of excretion or the functions of the liver and want to recall the key facts.