Homeostasis+Experiment+4A+and+4B

Experiment 4A - Beetroot Experiment
__Results and Observations__

Predictions and Observations of colour of the solutions after the experiment:
 * Solution || Prediction || Observation ||
 * A (4ml of water) || The beetroot cells will turn turgid and the solution will remain colourless. || The solution remained colourless. ||
 * B (25% alcohol) || The beetroot cells will become slightly flaccid and solution will turn into a light shade of pink. || The solution turned slightly pinkish. ||
 * C (50% alcohol) || The beetroot cells will turn flaccid and solution will turn very pinkish/red. || The solution turned dark pinkish/red. ||
 * D (Hot water) || The beetroot cells will turn very soft and flaccid and the solution will remain turn pinkish. || The solution turned slightly pinkish. ||
 * E (4ml of water- chopped beetroot) || The beetroot cells will turn turgid and the solution will remain colourless. || The solution remained colourless. ||

Results of Spectroreadings of solutions:
 * ~ Solution ||~ Spectroreadings/nm ||
 * A || 95.82 ||
 * B || 87.62 ||
 * C || 30.79 ||
 * D || 83.26 ||
 * E || 91.86 ||

__Discussion:__ The spectroreadings that were taken using the data logger determine the amount of light that is able to pass through the solutions. Before the experiment, the data logger is calibrated by making sure that 100% of light is able to pass through clear water. The spectroreadings are then taken for the various solutions after the beetroot cells are soaked in them for 15 minutes. The results have shown that Solution A (4ml of water) allowed the most amount of light (95.82%) to pass through, followed by Solution E with 91.86%, Solution B with 87.62%, Solution D with 83.26% and Solution C (50% Alcohol) allowed the least amount of light (30.79%) to pass through after the beetroot is soaked in it. The colour of the solutions changes overtime when the beetroot is soaked in the solutions as the pigments from the beetroot cells diffuses into the solution through osmosis and the pigments in the solution reduce the amount of light that is able to pass through the solution. The higher the rate of diffusion, the greater the amount of pigments in the solutions and this causes lesser amounts of light to be able to pass through the solution.

In Solution A (water), the solution appeared to be colourless after the beetroot cells are soaked in it and allowed the most amount of light to pass through. This is because water has a higher water potential than the beetroot cells, causing water to enter the beetroot cells through osmosis in order to achieve dynamic equilibrium. Therefore, more water molecules enter than escape the cell. However, although the solution appeared to be colourless, the amount of light that can pass through is not 100% as some pigments of the beetroot cells diffused in the water as the molecules move in and out of the cells through osmosis dynamically. As a result, Solution A would be clear and allow the most light to pass through. Solution E (water) in which chopped beetroot cells were soaked in allowed slightly lesser amount of light to pass through as the chopped beetroot have a larger surface area to the same volume and this allows a higher rate of diffusion to occur.

Solution D (50% alcohol) was observed to be dark pinkish after the experiment and allowed the least amount of light to pass through. This is because alcohol has a lower water potential than the beetroot cells, causing more water to escape than enter the cell through osmosis in order to reach dynamic equilibrium. Therefore, more pigments of the beetroot cells diffuse into the solution, causing water to turn dark pinkish and as result, allows less amount of light to pass through. In addition. 90% of the Beetroot cell membrane is made up of fats. Lipids are soluble to organic solvents with low molecular weight molecules such as alcohol. Therefore, when beetroot is soaked in the alcohol, the lipids would diffuse into alcohol.

Experiment 4B - Agar Experiment
__Results__ Table: Comparison of rate of conductivity change for different surface area to volume ratios
 * No. of pieces of agar cubes || Length (cm) || Surface area (cm2) || Volume (cm3) || Surface area to volume ratio || Rate of conductivity change (ms/s) ||
 * 1 || 2 || 24 || 8 || 3:1 || 1.16 ||
 * 8 || 1 || 48 || 8 || 6:1 || 2.06 ||
 * 64 || 0.5 || 96 || 8 || 12:1 || 2.68 ||

__Discussion__ The agar is made of sodium chloride that is constituently made up of sodium and chloride ions. When salt dissolves, the ions which carry charges are able to weaken their bonds and diffuse into the solution. The conductivity sensor is capable of monitoring the total concentration of ions in a solution. Hence it is used in this experiment to measure the rate of diffusion. From the results, we can see that the greater the surface area to volume ratio of the agar, the higher the rate of conductivity change. Therefore, this shows that with a greater surface area, a higher rate of diffusion is able to occur. More sodium and chloride ions are found in the solution containing the 64 pieces of agar cubes with a surface area to volume ration of 12 : 1 as compared to the solution containing the 64 pieces of agar cubes with a surface area to volume ration of 1:16, causing a higher conductivity change to be measured. As a result, we can conclude that the greater the surface area to volume ratio of substances, the higher the rate of diffusion.

Sources: http://rambio.wikispaces.com/02B_Agar+Experiment