Cell Membranes and Transport
Beetroot cells contain a red pigment, called betalains, which is stored in the vacuole of the plant cells. This is to prevent the pigment leaking out of the cell.  The outer layer of the cell is also surrounded by a membrane, this also helps the pigment stay inside the cell. Normally the pigments cannot pass through the membranes but they leak out when the beetroot is cooked.  The aim of this experiment was to use beetroot to examine the effect of temperature on cell membranes and relate the effects observed to membrane structure. To function correctly, a cell needs to be able to control transport across the partially permeable cell membrane.  A membrane is important in cells because it helps substances pass through into the cell and prevents the pass through of harmful substances through the cell. This is known as diffusion. Diffusion can be done naturally or by increasing the temperature or the concentration of the substance. This is known as facilitated diffusion. Hypothesis – An increase in temperature will damage and denature the membrane and cause the red pigment to leak out of the cell.
All experiments include hazards that could harm you. For example, using a scalpel blade to cut the beetroot accurately also gives the problem of cutting yourself with the blade. To prevent this, hands were kept as far away as possible from the blade. Rubber gloves could come in handy whilst doing this as they give a protective layer to your hands. A cutting tile would helpful too as damage to the table is less likely. Also, the fact that dealing with hot water and heating apparatus is a safety precaution as extra care is needed to prevent burns.
• Size 4 cork borer
• White tile
• Water baths at 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C • Plastic beaker, about 250cm3
• 2 boiling tube racks
• Crushed ice
• 8 boiling tubes
• Thermometer (one per...
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