Osmosis The diffusion of water molecules across a partially permeable membrane
Transcription
Osmosis The diffusion of water molecules across a partially permeable membrane
Osmosis The diffusion of water molecules across a partially permeable membrane Why do cells need water? Objectives by the end of this lesson • Describe osmosis • Explain how a model cell can gain or lose water by osmosis • Set up practical apparatus effectively to demonstrate osmosis Osmosis • Osmosis is the diffusion of water molecules across a partially permeable membrane. • What does partially permeable mean? • • What is diffusion? • What affects the rate of diffusion? Experiment to show osmosis This is left set up .What happens to the level of sucrose solution in the capillary tube? Water Explanation of results 1. Why does the sucrose solution move up the tube. 2. Where are there a lot of water molecules? 3. Where are there fewer water molecules? 4. In which direction do the water molecules move? Osmosis- Check your understanding • What will happen to a red blood cell if it is placed in a very dilute solution? • Explain your answer • What will happen to a red blood cell placed in a very concentrated solution? • Explain your answer