Excretion in Plants and Humans

IGCSE Edexcel Biology
2.70-2.71 Excretion
Key Concept: Excretion removes metabolic waste products from organisms.

Section A: Humans

1. State the excretory products of the lungs, kidneys, and skin. [3]

Section B: Plants

2. Explain how plants remove $CO_2$ and $O_2$ as waste products. [2]

Section C: Key Terms

3. Explain the difference between excretion and egestion. [2]
4. State where urea is produced in the body. [2]
Total marks: 9

Mark Scheme

1. Lungs: $CO_2$; kidneys: urea and excess water/ions; skin: sweat (water, salts, urea) [3]
2. Gases diffuse through stomata to the air [2]
3. Excretion is removal of metabolic waste; egestion is removal of undigested food [2]
4. Urea is produced in the liver [2]