Lesson 9: Diffusion

An all-in-one presentation and worksheet pack designed to teach diffusion, surface area to volume ratio and the adaptations of exchange surfaces. Features clear explanations, accessible diagrams, worked calculations, and activities designed to develop students’ understanding of how substances move into and out of cells and how organisms exchange materials efficiently.

Key Features:

• Explains diffusion and the net movement of particles from high to low concentration
• Covers examples of diffusion, including oxygen, carbon dioxide and urea transport
• Describes how concentration gradient, temperature and surface area affect the rate of diffusion
• Explains why single-celled organisms have a large surface area to volume ratio
• Covers how surface area to volume ratio affects the need for exchange surfaces and transport systems in multicellular organisms
• Includes surface area to volume ratio calculations and comparison questions
• Explains how fish gills are adapted for exchanging materials
• Includes a core knowledge worksheet
• Includes starter, retrieval and exam-style tasks
• Complete answer keys included throughout