O Levels/IGCSE Biology Lesson Plan 13.1

Section	Details
Objective	– Understand the process of excretion and its importance in removing metabolic waste.
Activities	Starter (5 mins): Ask students why organisms need to remove waste products. Main (25 mins): 1. Introduce excretion as the removal of waste products from metabolic activities. 2. Explain that carbon dioxide is excreted through the lungs and that urea, excess water, and ions are excreted by the kidneys. 3. Show diagrams of the human excretory system, identifying the kidneys, ureters, bladder, and urethra. Plenary (10 mins): Students summarize the main excretory organs and their functions in a table.
Resources	Diagrams of the human excretory system, whiteboard for notes.
Time	40 minutes
Homework	Write a paragraph explaining the role of the lungs and kidneys in excretion.
Assessment	Students correctly identify excretory organs and their roles during the class discussion.
Past Paper Practice	IGCSE Biology 0610/12/M/J/18 Q4(a).

Section	Details
Objective	– Identify the kidney structure and understand its role in filtration and urine formation.
Activities	Starter (5 mins): Recap the role of the kidneys in excretion. Main (25 mins): 1. Introduce the structure of the kidney, limited to the cortex and medulla. 2. Discuss the nephron as the functional unit of the kidney and outline its structure (glomerulus, tubules). 3. Explain filtration in the glomerulus and reabsorption of glucose, ions, and water. Plenary (10 mins): Students label a diagram of the kidney and nephron.
Resources	Kidney and nephron diagrams, whiteboard, markers.
Time	40 minutes
Homework	Write an explanation of how the nephron forms urine by filtration and reabsorption.
Assessment	Students correctly label the kidney and nephron diagrams and explain their functions.
Past Paper Practice	IGCSE Biology 0610/31/O/N/19 Q6(a).

Section	Details
Objective	– Understand the role of the liver in amino acid assimilation, deamination, and urea formation.
Activities	Starter (5 mins): Ask students why excess amino acids cannot be stored in the body. Main (25 mins): 1. Explain the liver’s role in converting amino acids into proteins. 2. Introduce deamination as the removal of the nitrogen-containing part of amino acids, forming urea. 3. State that urea is transported to the kidneys for excretion. Plenary (10 mins): Students summarize the process of deamination and urea formation in a flowchart.
Resources	Diagrams of the liver, flowchart templates, whiteboard.
Time	40 minutes
Homework	Research and describe the importance of the liver in maintaining amino acid balance in the body.
Assessment	Students create an accurate flowchart and explain the role of the liver during class discussion.
Past Paper Practice	IGCSE Biology 0610/22/M/J/18 Q5(b).

Section	Details
Objective	– Understand the importance of excretion in maintaining homeostasis and preventing toxicity.
Activities	Starter (5 mins): Ask students what would happen if metabolic wastes were not removed from the body. Main (25 mins): 1. Discuss the toxicity of urea and other wastes in the blood. 2. Explain how the excretory system maintains a balance of water, ions, and other substances. Plenary (10 mins): Students write a brief explanation of why excretion is vital for life.
Resources	Case studies of excretory system disorders, whiteboard.
Time	40 minutes
Homework	Write a short essay on how the excretory system contributes to homeostasis.
Assessment	Students provide accurate explanations of the importance of excretion during discussions.
Past Paper Practice	IGCSE Biology 0610/41/O/N/20 Q4(c).