Biology Practical 1 Report

Hong Hui Jing

28379489

Post-lab question

1. A line of best fit should be draw. A line of best fit as it will give an accurate representation of the relationship between absorbance and concentration between the different samples. The more samples used, the closer the results would be to the line of best fit.

1. It’s not possible to determine the protein concentration of a solution from the standard curve. This is because the data gathered from the standard solutions is in a certain range. The concentration of the solution is outside the range that is higher than the highest y-value on the standard curve. Therefore, the relationship between absorbance and concentration cannot be determined for anything outside of this range.
2. One way in which the experimental procedure could be modified is diluting the sample. This involves decreasing the volume of BSA Protein solution and increasing the buffer volume by the same amount. We can dilute the sample about 5 times lover than the actual concentration of the solution. As the result the absorbance would be lower and fit on the graph. In this case, we can determine the actual concentration of the solution by calculate 5 times larger than the concentration of the diluted sample. Another way may be to extend the curve by increasing the concentration of the BSA Protein solution which would provide a greater range. We can extend the curve larger to make sure the concentration of the solution can be fit on the graph.
3. The hypothesis regarding the tissue samples was supported. The absorbance of the sun raised silverbeet plant was found to be 1.564, which was greater than the shaded silverbeet plant with an absorbance of 1.124.

1.  A possible error may be adding inaccurate amounts of buffer between samples, causing them to dilute either excessively or insufficiently, resulting in an inaccurate standard curve. Another error could be leaving the sample solutions for over 25 minutes, which could cause the protein to start degrading. Not zeroing the spectrophotometer or cleaning the tube properly can affect the absorbance value.
2. Biological errors involve using different parts the plant, such as a stem or leaf and one may have a higher or lower absorbance than the other. Another reason may be that different aged samples were used, such as a baby plant which may have a higher absorbance compared to an aging plant. Furthermore, the sun raised silverbeet plant could have had excessive exposure to the sun and was beginning to die, causing a lower absorbance.
3. Rubisco is not the only protein in the plant as it makes up 80% of the total protein in plant leaves. This means that there is 20% of other existing proteins that may have contributed to the results.

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