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Beet Lab. Aim: To determine the effects of temperature on the permeability of the beetroot cell membrane.

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´╗┐Biology HL Lab Report Beet Lab Data Collection, Processing, Presentation Conclusion & Evaluation -Rashika Singh IB Yr 1 Aim: To determine the effects of temperature on the permeability of the beetroot cell membrane. Research Question: To investigate how different temperatures affect the beetroot pigment and finding out the absorbance and transmittance % using a visible spectrophotometer. Background Information: Beetroots contain betalains which are the red pigments present in the cell vacuole. Betalains are soluble in water and they contain nitrogen. Betalains extracted from beetroot is commonly used as food dye because it is not known to cause any allergic reactions. Cell membrane is the barrier that separates the inner environment of the cell from the outer environment. The membrane is selectively permeable. The cell membrane is made up of mainly lipids, carbohydrates and proteins. The lipids are the phospholipid bilayer which consists of a hydrophilic polar head and a hydrophobic tail. Among the proteins present in the cell membranes are integral proteins and peripheral proteins. {1} Lipids increase in fluidity as temperature increases. Once denatured, proteins start to unravel and are unable to carry out their function. Diffusion is the movement of molecules from high concentration to a low concentration down a concentration gradient. Facilitated diffusion and active transport requires assistance from proteins imbedded in the cell membrane to transport substances in and out of the cell. Any damage to the cell membrane will cause the cytoplasm to leak out of the cell. ...read more.


This may have an effect on the actual temperatures inside them and could mean a deviation from the originally planned temperatures. Apparatus: 1. Spectrophotometer 2. 5 test tubes 3. 5 water baths (20oC, 30oC, 40oC, 50oC, 60oC) 4. Hot water 5. Ice 6. Labels 7. Stopwatch 8. Glass stirring rod 1. Mounting needle/forceps to handle beetroot cores 2. Syringe 1. Thermometers for each water bath 2. 5 cuvettes Procedure: 1. Obtain the beetroot cores from the lab technician. 2. We put each of the beetroot cores in each of test tubes. 3. Using a syringe, we fill up 10 ml of water and pour it into the test tubes. 4. Meanwhile prepare the water baths (20oC, 30oC, 40oC, 50oC, 60oC). 5. When the water baths are ready, place each test tube in each of the water baths. Have your stopwatches ready. 6. Keep the test tubes for exactly 10 minutes in the water baths. 7. After 10 minutes, take out the test tubes, discard the beetroot cores and pour out its contents, the pigmented water, into the cuvette. 8. Ask the lab technician to help you calibrate and warm up the spectrophotometer to 480.5nm 9. Using one cuvette for each trial, measure out the absorbance and transmittance %. 10. Repeat steps 1-9 for all trials. 11. Record your observations in a table. Precautions: 1. Make sure you don?t spill out anything. 2. Beware of the hot water baths; use a test tube holder to take out the test tube from the hot water baths. ...read more.


2. Inability to maintain temperature of water baths Many times we were unable to follow the temperature trail, which would result in a varied membrane absorbance, with the temperature drop when all test tubes were put in the water baths, hence giving us inaccurate results. 3. Spilling of liquids Most if the coloured pigment water may spill out, hence not giving us the respective colours, and will result in inaccurate spectrophotometer readings which acts as major error instigator. Be more careful in handling the liquids to prevent spilling of anything. If anything does spill, redo the entire experiment again. 4.Timekeeping The test tubes of beetroot cores were places a little too early or a little too late. As the amount of time increases, the amount of diffused pigment will also increase. Overshooting of time for the test tubes in the water baths will have resulted in accumulated errors. Coordinate efforts and place the test tubes in the water baths at the same time to reduce errors as mentioned above. Stay to your time limit, and never overshoot the time. 5. Confusion to procedure Many times confusion in procedure will contribute lots of errors to the readings. Come prepared and read the procedure and precautions before you start the lab. If there is any confusion, do not hesitate to ask the lab assistant. 6. Large margins between different trials 7. The pH of the water Most of the times tap water is used, and tap water contains a lot of impurities, which affect the permeability of the membrane. Use of distilled water to prevent impurities that might alter the pH. ...read more.

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