Diffusion and osmosis
- 1. Diffusion, osmosis and active transport LO: To learn how substances get into and out of cells. Thinking question: How are oxygen and carbon dioxide transported in your body? Oxygen is transported by the red blood cells and carbon dioxide is transported in your blood plasma.
- 2. Learning outcomes • Describe the meaning of the term diffusion, osmosis and active transport. • Explain examples of where diffusion and osmosis occur in the human body • Suggest reasons why active transport is different to diffusion and osmosis. • Stretch: Create model answers to past exam style questions.
- 3. Diffusion • This is a process that is vital to all living organisms. • Diffusion is when molecules move from an area of high concentration to a lower concentration until equalibrium is reached. • We say the molecules diffuse along a concentration gradient.
- 4. Diffusion
- 6. Diffusion in your body • Task: On your paper, write down how oxygen moves from the lungs into the cells in the body that need it (e.g. brain cells). • Thinking prompts: • Where does it enter your body? • Where will the concentration of oxygen be highest? • Keywords: oxygen, concentration, red blood cells, diffuse, high, low, brain cells.
- 7. Your idea time On your paper write down what you think the term active transport means.
- 8. Active transport • Active transport is when cells move molecules in the opposite direction, against the concentration gradient. • This process requires energy. • If you are asked for an example in your exam, glucose is absorbed from the small intestine into the blood by active transport.
- 9. Learning check • Have a go at the two learning check questions to make sure you understand diffusion and active transport. • What is diffusion? • Diffusion is when molecules move from an area of high concentration to a lower concentration until equalibrium is reached. • What is active transport? • Active transport is when cells move molecules in the opposite direction, against the concentration gradient.
- 10. Osmosis • Osmosis is when water diffuses through a partially permeable membrane so that the concentration on each side becomes more equal. • So, the movement of water is from a dilute to more concentrated solution.
- 11. Lets look at it in detail A
- 12. What happens next? • A chip is placed into the following beakers. What will happen to the size of the potato chip? Explain your answer.
- 15. Gill and Jon
- 16. What have you learned today? • Describe the meaning of the term diffusion, osmosis and active transport. • Explain examples of where diffusion and osmosis occur in the human body • Suggest reasons why active transport is different to diffusion and osmosis. • Stretch: Create model answers to past exam style questions.
- 17. Extension • The cells in your body are surrounded by a liquid called tissue fluid, which contains dissolved substances. • If the tissue fluid is more dilute than the fluid inside the cells, what will happen?