Nerve cells Can carry electrical messages. Can pass the message to another nerve cell. This enables us to think, feel, move, taste, smell, see and hear.
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Plant cells Contain chloroplasts for photosynthesis. Have a cell wall to give support to the plant. Have a large vacuole to give shape to the cell.
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Activity Examine different types of cells using a light microscope: Examine a variety of prepared cells under the microscope. Note the difference in their structure. Make simple drawings of what you see.
Activity Movement across a semi-permeable membrane
The cell membrane is a structure that allows some but not all substances to move in and out of the cell. It is said to be semi-permeable. This experiment will demonstrate how substances can move through a membrane. The membrane used in the experiment is called ‘visking tubing’. It allows the movement of small molecules through it, similar to the cell membrane.
Apparatus Two lengths of visking tubing, approximately 25 cm long each Two beakers of water labelled A and B Starch solution Iodine solution Two glass rods
Method 1. Soak the visking tubing in warm water for two minutes to soften. 2. Remove the visking tubing and tie one end of each tube. 3. Two-thirds fill one tube with starch solution. 4. Two-thirds fill another tube with water. This is a control experiment. 5. Remove any air and make sure the tubes are not completely full before tying the ends. 6. Add a few drops of iodine solution to two beakers of water. Label A and B. 7. Place the visking tubing with starch solution into beaker A, and the visking tubing with water into beaker B. Leave for 20-30 minutes.
8. Remove and dry each tube and observe any changes in the tubes and in the water. Record your observations in the following table.
