02C_Beetroot+Experiment

Biology lab report-Beetroot experiment __** Aim: **__ To explore the factors which affect the movement of materials in and out of the cells

__** Hypothesis: **__ The beetroot in tube C would lose the most pigments to the solution it is soaked in (50% alcohol) while the beetroot in tube A would lose the lease pigments to the solution it is soaked in (water). This is because the alcohol would cause the most damage to the cell membrane of the beetroots, causing more pigments to leak out.

__** Method: **__ Step 1: Use a ruler and scalpel to cut the cylinder of beetroot into 15 discs of 2mm each on a white tile. Use forceps to grip the beetroot while cutting.

Step 2: Take 3 discs of beetroot and cut them further into smaller pieces on a white tile. Use forceps to grip the beetroot discs while cutting.

Step 3: Rinse the beetroot discs and pieces in a beaker until the water is colourless. This is to prevent the beetroot from releasing pigments into the solutions immediately after being placed in them, as it would affect the results. (Pigments released would not be because of reactions between the cell membrane and solution)

Step 4: Label and prepare 5 test tubes. Use the droppers provided to measure the liquids, being sure to use each dropper for one kind of liquid only.

Label as follows:
 * 1) Test tube A- 4ml of water
 * 2) Test tube B- 4ml of 25% alcohol
 * 3) Test tube C- 4ml of 50% alcohol
 * 4) Test tube D- 4ml of hot water (90 degrees to 100 degrees)
 * 5) Test tube E- 4ml of water

Step 5: Place 3 discs of beetroot into tube A-D and all the chopped beetroot into tube E using forceps.

Step 6: Leave the tubes to stand in the test tube rack for 15 minutes. Use the stopwatch to time the experiment. Step 7: During the 15 minutes, set up the colorimeter. Step 8 - Fill a cuvette with water from the tap until the mark. Hold the cuvette by its rough sides (the sides with ridges) and not the smooth sides to prevent any fingerprints on the smooth sides that will affect the colorimeter and the results. Step 9 - Make sure that the sides of the cuvette are dry by wiping it with a cloth before placing the cuvette in the colorimeter and holding the cap close. Step 10 - Adjust the colorimeter by twisting the knob on the colorimeter and adjusting it until the screen registers 100%. This is to calibrate the machine by using water that allows 100% of the light to pass through. Step 11 - After 15 minutes, shake the test tube gently and hold it against the white tile to note the color. Record down the observations in a table. Step 12 - Using the dropper, decant a small amount of the liquid from test tube A into the cuvette and fill it up to the brim. Place the cuvette into the colorimeter. Step 13 - Click “run” to record the value of light transmission once the value is relatively steady into the table drawn. Step 14 - Repeat Steps 11-13 for all the test tubes and record the results in a table.

__** Results **__

** Test Tubes ** || ** Liquid in Test Tube ** || ** Size of Beetroot ** || ** Value on Data Logger / % ** || A || 4ml of Water || 2mm || 96.3 || B || 4ml of 25% alcohol || 2mm || 85.0 || C || 4ml of 50% alcohol || 2mm || 94.3 || D || 4ml of hot water (90-100 degrees) || 2mm || 93.8 || E || 4ml of Water || 1/4 of 2mm || 93.7 ||

__** Analysis **__ There is a mistake in the data. The value on the data logger for test tube C should be the lowest as the high concentration of alcohol would damage the cell membrane, and hence cause more pigments to leak out. This would make the solution a darker colour, allowing less light to pass through. However, the other results are quite reliable as the 25% alcohol has quite a low value on the data logger. This value should be higher than that of the value for test tube C as there is a lower concentration of alcohol, hence damaging the cell membrane less, allowing less pigment to leak out. The value for test tube A is also quite reliable as it is lower than 100%, but the highest out of all the other test tubes. This is correct as the water would damage the cell’s membrane the least, causing the least amount of pigment to leak out. The value for D is lower than that of A but higher than that of B and C. This is probably because the hot water would cause more pigments to leak out of the cells than the regular water in A would, but not as much as the water with varying alcohol concentrations in B and C would. Lastly, the value of E is lower than A but higher than the others. This is because when the beetroots are chopped up, there are more exposed surface areas, allowing the pigments to leak out of the cells more efficiently, hence causing the solution to turn darker than the solution in test tube A, resulting in a lower value on the data logger.

__** Discussion Questions **__ Test tube A.
 * 1) What was the control in this activity?

__** Scenario 1 **__ Control- test tube A Variable- test tube D  Independent variable- temperature of water __** Scenario 2 **__ Control- test tube A Variables- test tubes B and C  Independent variable- Concentration of alcohol __** Scenario 3 **__ Control- test tube A Variable- test tube E  Independent variable- Size of beetroot
 * 1) How do you analyse the results of this experiment on variable at a time?

It is to prevent the beetroot from releasing pigments into the solutions immediately after being placed in them, as it would affect the results. The pigments released would not be because of reactions between the cell membrane and solution
 * 1) Why was it necessary to wash the beetroot slices thoroughly before using them in the experiment?

We washed the beetroots before the experiment till the water turned colourless, implying that the excess pigments had been washed away, leaving each beetroot with only the amount of pigments it can contain (not excess pigments).
 * 1) The main source of error in any biological experiment is usually the natural variation of living things. What did you do to ensure that his variation was minimised?

Yes. It damages the beetroot cell membrane, allowing the pigments to leak out. The higher the concentration of alcohol, the more damage it will cause to the cell membrane, disallowing it from carrying out its function of holding substances in within the cell. Hence, more pigments will leak out. Tube D had a lower reading than tube A. This is because the temperature of the water had an effect on the amount of damage caused to the cell membrane. The hotter the water, the more damage there will be cause to the cell membrane, the more pigments will leak out. Tube E had a lower reading than tube A. This is because the chopped up beetroot had more exposed surface areas, allowing the pigments to be released faster and more efficiently through more “exits”.
 * 1) Does alcohol have an effect on beetroot cell membranes? Was the concentration of alcohol a factor too? Suggest an explanation for your observations
 * 1) Suggest an explanation for the observations of tube D & E too.


 * 1) What are factors can you think of that would affect the leaking of the pigment out of the beetroot cells?