Normal and Plasmolyzed Cells Name: _______________________________
- What is diffusion?
- Diffusion of water is called ___________________________________________
Water loss in a cell is called plasmolysis. Plasmolysis occurs when the water concentration inside the cell is higher than the concentration of water outside the cell. You will observe this process in this lab.
Materials
Slide cover slip Red Onion 6% salt water tap water
Procedures:
- Put two drops of tap water on a slide and add a small piece of a red onion skin.
- Put two drops of salt water on a slide and add a small piece of a red onion skin.
- Add cover slips to both slides.
- Wait about two minutes.
- Observe each slide under low and high power.
- Diagram a single cell (about one inch in length). Label the cell membrane and cell wall in both cells.
- Hint: Can you clearly see the cell membrane in both cells or only one?
Tap Water Salt Water
Lab Analysis: Consider the following before answering the questions.
- Onion cells normally contain 1% salt and 99% water on the inside
- Tap water usually contains 1% sale and 99% water.
- Salt water used in this lab contains 6% salt and 94% water.
- Which has a high concentration of salt? (circle)
salt water fresh water onion cells
- Where are the red pigments located in the onion cell?
- Which cell has undergone plasmolysis? Explain.
- What is the percentage of water outside the cell in tap water?
5. What is the percentage of water inside the cell in tap water?
6. How do the percentages compare? Did the cell shape change?
- What is the percentage of water outside the cell in salt water at the beginning of the lab?
- What is the percentage of water inside the cell in salt water at the beginning of the lab?
- Is the percentage of water inside the cell higher or lower than the percentage outside (for salt water)?
- Did the inside of the cell change shape due to water loss? Explain: