Biology Lab: Osmosis (Onion Peel)
Explore the process of osmosis using a virtual onion peel lab. Order the steps of the experiment and match the cell diagrams to their corresponding osmotic states.
Help & Instructions
â–¼- Experiment Steps: Drag and drop the steps to put them in the correct order of the osmosis experiment.
- Cell States: Drag the correct labels to the corresponding images of the onion cells.
- Use the hint button if you need help with a puzzle.
- Try different challenges to reinforce your understanding.
- Describe the process of osmosis in plant cells.
- Understand the concepts of hypotonic, hypertonic, and isotonic solutions.
- Identify the effects of different solutions on onion peel cells.
- Explain the phenomena of plasmolysis and turgor pressure.
Experiment Steps: Order the Process
Arrange the steps of the onion peel osmosis experiment in the correct order.
Osmotic States: Match the Labels
Match the labels to the correct images of onion cells.
**Osmosis** is the movement of solvent molecules (like water) from a region of higher water potential to a region of lower water potential through a selectively permeable membrane. In the context of a plant cell, this movement is vital for maintaining turgor pressure. When an onion peel cell is placed in different solutions, water moves into or out of the cell, causing visible changes.
Key Concepts of Osmosis
- **Hypotonic Solution:** A solution with a lower solute concentration than the cell. Water moves into the cell, causing it to swell and become **turgid**.
- **Hypertonic Solution:** A solution with a higher solute concentration than the cell. Water moves out of the cell, causing the plasma membrane to shrink away from the cell wall, a process called **plasmolysis**.
- **Isotonic Solution:** A solution with an equal solute concentration to the cell. There is no net movement of water, and the cell remains in a **flaccid** state.
This classic experiment uses the thin, transparent epidermal peel of an onion. The cells are placed on a slide and observed under a microscope after adding drops of distilled water (hypotonic), a salt solution (hypertonic), or a neutral solution. The visible changes in the cell's turgidity or the onset of plasmolysis provide direct evidence of osmosis.
The cells of an onion peel are ideal for this experiment because they are large, have a distinct cell wall and cell membrane, and their transparency allows for easy observation of the changes under a microscope.
