Membranes Under Stress

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Membranes Under Stress
Properties of Cell Membranes

Investigate the effect of different substances on beetroot cell membranes. From the results, make some references about the structure of cell membranes.

Refer to sheet.

Refer to sheet

Table 1: Intensity of pigment colour in solutions
Time (from start)Distilled WaterpH
2 4 7 9 10 Alcohol
1% 25% 50%Detergent
1% 5%
Observation 113 2 1 0 01 2 3 2 1
Observation 2 14 3 0 1 11 3 4 4 1
Observation 323 4 1 2 1 1 2 3 5 2

1.Does pH have an effect on beetroot cell membranes? Was time a factor? Explain your observations. According to the results (above), the lower the pH the higher the effect on the beetroot cell membranes; there was a very low colour change in the surrounding medium when a pH level was greater than 7. This may have occurred because pH 7 is neutral and a pH greater than 7 is basic or alkaline. At a pH level greater than or equal to 7, the solution was unable to breakdown the beetroot cell membrane because it is a strong base, which does not have the properties to breakdown a cell membrane. The solutions with a pH level of less than 7 had a higher amount of red pigment in the surrounding medium. This is because a pH of less than 7 is acidic and therefore has a greater effect on the beetroot cell membrane. The acidic pH solution broke down the beetroot cell membrane, and therefore the red pigment leaked into the surrounding medium. From observations (above), it does not seem that time was a significant factor, in considering the effects of pH in the experiment. Throughout the whole experiment, there was not a big difference in pigment colour in the solutions, the results were constant.

2.Does alcohol (ethanol) have an effect on beetroot cell membranes? Was time and/or concentration a factor? Explain your observations. From the results (above) it is...
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