Homeoostasis+Exploration+4A+(Beetroot)

Homeostasis Exploration 4A Movement In and Out of Cells (Beetroot)

Aim: To explore the factors which affect the movement of materials in and out of cells

Results:
 * Test tube || Colour observed after 15 minutes || Percentage registered in the data logger (%) ||
 * A (4 ml of water) (3 discs of beetroot) || Pink || 89.3 ||
 * B (4 ml of 25% alcohol) || Pink || 91.65 ||
 * C (4 ml of 50% alcohol) || Dark pink || 63.45 ||
 * D (4 ml of hot water between 90°C and 100°C) || Light pink || 103.93 ||
 * E (4 ml of water) (chopped beetroot) || Pink || 86.68 ||

Discussion Questions: Q1) What precautions did you take in this experiment? Ans: I made sure that the solutions all had an equal volume of 4 ml, and that the beetroot were evenly cut into slices of 2 mm each. Also, when handling a cuvette, I made sure that I didn't touch the smooth sides and all sides were dry.

Q2) How do you analyse the results of this experiment one variable at a time? Ans:

Q3) Why was it necessary to wash the beetroot slices thoroughly before using them in this exploration? Ans: It was important because there might be dirt on the beetroot and it would have affected the rate of diffusion.

Q4) The main source of error in any biological experiment is usually the natural variation of living things. What did you do to ensure that this variation was minimised? Ans: The main source of error and largest variation would be the level of betalain in each beetroot cell. Some beetroot stalks would have lower levels and some higher levels, resulting in the variation. So minimise this variation, I can take all 15 discs from the same stalk of beetroot.

Q5) Does alcohol have an effect on beetroot cell membranes? Was the concentration of alcohol a factor too? Suggest an explanation for your observations. Ans: Yes, alcohol had an effect on beetroot cel membranes. When the concentration of alcohol was 25%, the percentage registered in the data logger was 91.65% and when the concentration of alcohol was 50% the percentage registered in the data logger was 63.45%. So the concentration of alcohol was a factor. It was so because due to the high concentration of alcohol (50%), the concentration of water in the beetroot was higher than the concentration of water in the solution. As a result, osmosis, which is the net movement of water particles from regions of higher concentration to regions of lower concentration, occurs. When there is less water, less light can go through the solution sample, reducing the light transmission level. When the concentration of alcohol was lower, less osmosis occurred due to the reduced difference in the water levels between the beetroot and the solution. Hence, when there was relatively more water in the solution sample, more light could pass through and raised the light transmission level.

Q6) Suggest an explanation for the observations of tube D and E too. Ans: The light transmission levels were tube D and E were 103.93% and 86.68% respectively. The light transmission level for tube D was slightly higher than that of the control sample. This may be because that sine the water in tube D was heated and so the water molecules could move faster and more osmosis could occur, raising the water level. As a result, the solution sample from tube D had a slightly higher light transmission level. For E, there was a significant increase in total surface area, meaning that more osmosis could happen. However, the difference between the light transmission levels of tube E and the control is not large.

Q7) What are the factors can you think of that would affect the leaking of the pigment out of the beetroot cells?Ans: I think that temperature, concentration of alcohol and the total surface area involved would affect the leaking of the pigment out of the beetroot cells. Although the total surface area does not matter much.

Conclusion: Data shows that the temperature, concentration of alcohol would affect the movement of materials in and out of cells.