Topic: Osmosis
Lesson 1: Introduction to Osmosis
| Section | Details |
|---|---|
| Objective | – Understand that water diffuses through partially permeable membranes by osmosis.– Describe the role of water as a solvent in organisms with reference to digestion, excretion, and transport. |
| Activities | Starter (5 mins): Show a simple animation of water molecules moving across a partially permeable membrane and ask students what they observe.Main (25 mins): 1. Define osmosis as the movement of water molecules through a partially permeable membrane.2. Explain the role of water as a solvent in biological processes (e.g., dissolving nutrients for digestion, transporting substances in blood, and aiding excretion).3. Provide real-life examples of osmosis, such as absorption of water by plant roots.Plenary (10 mins): Students summarize osmosis in one sentence and provide an example. |
| Resources | Animation of osmosis, diagrams of water movement, worksheets for labeling diagrams. |
| Time | 40 minutes |
| Homework | Write a paragraph explaining the importance of water as a solvent in digestion and transport. |
| Assessment | Students explain osmosis and its role in biological processes during class discussions. |
| Past Paper Practice | IGCSE Biology 0610/21/M/J/19 Q3(a). |
Lesson 2: Investigating Osmosis
| Section | Details |
|---|---|
| Objective | – Investigate osmosis using materials such as dialysis tubing.– Understand that water moves into and out of cells by osmosis through the cell membrane. |
| Activities | Starter (5 mins): Show a simple setup of dialysis tubing filled with sugar solution and ask students to predict what will happen when it is placed in water.Main (25 mins): 1. Set up an experiment using dialysis tubing to demonstrate osmosis: – Fill the tubing with sugar solution and submerge it in water. – Record observations of water movement and measure any changes in mass or volume.2. Discuss the movement of water molecules into or out of the tubing and relate it to osmosis in cells.Plenary (10 mins): Students summarize the experiment’s results and explain how it demonstrates osmosis. |
| Resources | Dialysis tubing, sugar solution, beakers, water, scales for measuring mass. |
| Time | 40 minutes |
| Homework | Write a report on the dialysis tubing experiment, including observations and conclusions. |
| Assessment | Students correctly describe the movement of water during the experiment and relate it to osmosis. |
| Past Paper Practice | IGCSE Biology 0610/22/O/N/18 Q4(b). |
Lesson 3: Osmosis and Plant Tissues
| Section | Details |
|---|---|
| Objective | – Investigate and describe the effects on plant tissues of immersing them in solutions of different concentrations.– Understand that plants are supported by water pressure inside cells pressing outward on the cell wall. |
| Activities | Starter (5 mins): Show an image of a wilted and a healthy plant and ask students what might cause the difference.Main (25 mins): 1. Perform an experiment with plant tissues (e.g., potato strips) in solutions of varying concentrations: – Place strips in distilled water, isotonic, and concentrated sugar solutions. – Record changes in length, mass, or appearance.2. Discuss terms like turgid, flaccid, and plasmolysis to describe the observed effects.3. Relate findings to water pressure supporting plant cells.Plenary (10 mins): Students explain why plants wilt in dry conditions. |
| Resources | Potato strips, sugar solutions of varying concentrations, beakers, rulers, scales. |
| Time | 40 minutes |
| Homework | Write an explanation of how osmosis affects plant cells in concentrated and dilute solutions. |
| Assessment | Students explain changes in plant tissues during the experiment using appropriate terms. |
| Past Paper Practice | IGCSE Biology 0610/32/M/J/20 Q3(b). |
Lesson 4: Water Potential and Osmosis in Organisms
| Section | Details |
|---|---|
| Objective | – Describe osmosis as the net movement of water from higher to lower water potential through a partially permeable membrane.– Explain the importance of osmosis in the uptake and loss of water by organisms. |
| Activities | Starter (5 mins): Show an animation of water potential gradients and ask students to explain the direction of water movement.Main (25 mins): 1. Define water potential and its role in osmosis.2. Discuss examples, such as water absorption by root hair cells and water loss in animal cells when placed in hypertonic solutions.3. Explain the importance of maintaining water balance in cells and organisms.Plenary (10 mins): Students summarize the importance of osmosis for living organisms. |
| Resources | Animation of water potential gradients, diagrams of osmosis in plant and animal cells. |
| Time | 40 minutes |
| Homework | Write a paragraph explaining the importance of water potential in maintaining water balance in the human body. |
| Assessment | Students correctly describe water potential and its effects during class discussions. |
| Past Paper Practice | IGCSE Biology 0610/41/O/N/19 Q2(a). |
Key Notes for Teachers:
- Use animations and practical demonstrations to explain osmosis visually.
- Encourage students to use terms like “turgid,” “flaccid,” and “plasmolysis” correctly when describing plant cells.
- Relate osmosis to real-life biological processes, such as water absorption and excretion.
Key Notes for Students:
- Remember: Osmosis is the movement of water molecules from a region of higher water potential to lower water potential through a partially permeable membrane.
- Be familiar with terms like turgid, flaccid, and plasmolysis.
- Understand the importance of osmosis in maintaining water balance in cells and organisms.
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