Lab Report 1 : Instructions and Guidelines
The following pages provide a scrambled report of two (2) actual lab reports.
Your job is to unscramble the mess and extract the information to generate one (1) complete lab report.
The report also has no headings. You will need to put the correct paragraphs within the corresponding headings. In addition, the paragraphs need to be put in the correct order.
Here are the Headings you will use:
Introduction
Materials and Methods
Results and Discussion
In other words, when you are finished, it should read as one well organized and logical report.
In addition, you will need to provide TWO tables (2) and one (1) figure.
There are 4 data tables provided at the end, containing the raw data for this lab report. Only one (1) has the correct data that corresponds with the lab-report you decide to make. Your job is to find that correct table and generate a new table with the normalized data in it. Correlate the content of the lab report with the data in that table, and then generate a figure from it. The normalization process is explained above the tables found below.
Your lab report needs a Table with the original data ( just copy and paste the correct one from below) and a Table with the normalized data ( this is where you adjust the data so they can be graphed properly).
The tables need to come on a separate page with correct legends. Keep your tables at a similar size as shown below.
The Legend (heading) of the table needs to be on top of the table and be referred to as follows
Table 1 : The original data of…..
There should be enough information in the heading of the table so that the reader has a clue of what the table contains. The following is not a good example of such a heading since it does not provide enough information.
Table 1 : The data of the experiment.
The figure needs to be made from the normalized data and shown on a separate page as well, also with a correct legend. In this case the legend comes below the figure. Make sure that your figure has different data symbols for each different condition and that these symbols are explained in the figure legend.
Remember that figures require a labelled X-axis and Y-axis label in order to make sense of the figure.
A nice link on how to deal with Tables and figures are in the following link :
Scroll down this website to where it explains about Tables and figures.
When finished, add on a coversheet with a title to the paper and your name a few spaces below it. The title needs to be informative and needs to be at least 5 words long and maximum 10 words.
This is not a tough lab report since it is already done for you. Your job is to use your biology knowledge to extract the correct information and line it up accordingly.
Points will be earned for correctness of the paper, correctness of the tables and graph , and presentation. Make sure your Tables and Graph have the correct and informative legends with appropriate symbols. DO NOT USE COLORS IN FIGURES. IT SHOULD BE BLACK AND WHITE !
What follows below is the scrambled content of two lab-reports. Extract the paragraphs that belong to one such lab report and generate a paper from it.
These observations agree with our stated hypothesis and the laws of thermodynamics. The gain or loss in weight is a direct consequence of the water concentration gradient created by the experimental setup. Furthermore, no change was observed in our control setup ( a dialysis bag filled with distilled water placed in a distilled water environment) providing additional support that the weight changes were due to a net movement of water in or out of the bag.
We believe that this indicated that either the reaction was running out of substrate, or that the enzyme became denatured. Figure 1 clearly shows that the linear aspect of the reaction was affected after 30 seconds at pH 8.0 and after 1 minute at pH 7.0 .
The purpose of the experiment was to demonstrate the aspects of osmosis. Using dialysis bags filled with solutions containing different concentrations of a specific solute, data are presented indicating the movement of water from a high effective water concentration to a low effective concentration.
The original data with respect to the described experiment, displayed in Table 1, were normalized to time zero and are shown in Table 2 . A clear increase in the weight of the dialysis bags can be seen for dialysis bags 3 and 4. The weight of dialysis bag 1 did not change appreciably while the weight of dialysis bag 2 decreased over time. Figure 1, in which the relative weight gain with respect to time zero (0) is plotted versus time , shows this pattern clearly.
Changes in substrate concentration, enzyme concentration, temperature and pH all have been implicated in affecting the rate of the reaction in which the enzyme is involved in. The purpose of this experiment was to examine the influence of pH on the enzyme activity. The enzyme used for this experiment was catechol oxidase.
Four 250 ml beakers were filled with 200 ml distilled water ( beaker 1,3 and 4 respectively ) and 200 ml 30% sucrose (beaker 2). Each dialysis tube was carefully tied at the bottom with a 10 cm string and then filled with 10 ml of distilled water (dialysis bag 1 and 2), 10 ml of 15% sucrose (dialysis bag 4) and 10 ml 30% sucrose (dialysis bag 3) respectively using a 10 ml graduated cylinder. After filling, the dialysis bags were securely tied at the top.
Five test tubes were filled with 5 ml of pH 4, pH 5, pH 6, pH 7 and pH 8 respectively. To each test tube, 5 drops of 1 % catechol were added using a plastic pipette and the test tube was mixed by inversion. To the first test tube containing pH 4, 5 drops of enzyme solution was added, quickly mixed and a sample immediately added to a spectrophotometer cuvette.
Considering our book knowledge on enzymes and pH, our working hypothesis is that pH indeed will have an effect on enzyme activity. More specifically, we hypothesize that the more acidic the environment, the more the enzyme will become denatured and the slower the enzyme will function.
Osmosis is a special case of diffusion since it involves the diffusion of water from a hypotonic area to a hypertonic area across a semi-permeable membrane. Since almost all cells bathe in an aqueous medium, the principle of osmosis is at the basis of most water exchange across a cell membrane.
Our conclusion from the data is that the enzyme thus has an optimal pH activity around pH 7, which most likely corresponds also with the intracellular pH of the cells where the enzyme is found. Increasing acidity or alkalinity on either side of pH 7 results in progressive denaturation, and progressive decline in activity of the enzyme catechol oxidase.
Diffusion is a physical phenomena resulting from the second law of thermodynamics which states that everything in the universe strives for maximal entropy. Diffusion is the movement of molecules move from a region of high order (a high concentration) to a region of low order (low concentration). Diffusion will proceed passively until all molecules involved are evenly distributed, reaching a state of maximal entropy, maximal chaos.
The enzyme catechol oxidase was extracted from a peeled potato. A 15 g piece of potato was homogenized for 1 minute in 150 ml of distilled water using a common blender. The mixture was allowed to settle on ice and subsequently filtered through a piece of cheesecloth. Once again this filtarte was allowed to settle and the top 50 ml was decanted and used as the source of substrate.
This procedure was repeated until each bag was weighed four times. The data with respect to the described experiment, were normalized to time zero such that all first data point read time zero and weight zero. All sequential data points thus reflected time change since the first time point and weight increase or decrease since the first measurement.
Enzymes are cellular proteins with a very specific action in that they function as biological catalysts. In other words, they speed up biochemical reactions in cells and thus significantly enhance the rate of substrate turnover. In addition, enzymes are very specific in that they catalyze only one specific reaction , using only one specific substrate. Cells contain hence an enormous amount of different enzymes, each involved in a very specific reaction. Without enzymes, most biochemical reactions would occur at a rate far too slow to maintain cells functional.
The initial slope of the line graph of each experiment provides the rate of the enzyme reaction. It is the Absorbance change per time unit, or an index of product formation per time unit. It thus provides us with an indication of the initial enzyme activity. The figure clearly shows that the enzyme has its lowest activity at pH 4, progressively increases at higher pH’s with its highest activity at pH 7. Beyond pH 7, the activity declines again due to the inactivation of the enzyme.
Although the changes at the molecular level cannot be seen, the use of weights of the bags as an index of water movement across the membrane of each dialysis bag provides us with an indirect but clear understanding of the mechanism at work.
Catechol oxidase is present in a variety of plants and uses oxygen and catechol as substrates to produce benzoquinone and water as products. The product benzoquinone has a brownish color and appears to function as an inhibitor for microbial growth. The formation of brown spots on peeled potatoes and bruised grapes are example due to the formation of benzoquinone upon exposure of cellular catechol to oxygen.
At time point 0, each bag was dipped in their respective beaker with solution, padded dry, weighed to the nearest 0.1 g using an electronic balance, the weight noted and immediately placed back in their respective beaker. At sequential 10 min. intervals, each bag was removed, padded dry and weighed again before returning to their container.
The cuvette was inserted into the spectrometer and the Absorbance was measured every 15 seconds for a total period of 90 seconds. This procedure was repeated for every pH condition. The data were normalized by assigning the first data point of each experiment a time of zero and an Absorbance of zero.
The absorbance was measured at 400 nm since at this wavelength, catechol does not absorb any light whereas the product of the reaction. Benzoquinone, does absorb light energy. According to Beer’s law, the amount of light absorbed is directly proportional to concentration, allowing us to obtain a relative index on product formation during the specific conditions of the reaction examined.
The actual absorbance data and normalized absorbance data of the experiment are tabulated in Table 1 and Table 2 respectively. The graph of the normalized data is shown in Figure 1. As can be seen in Table 2 , at each pH, the Absorbance increased over time., indicating that concentration of the product increased almost linearly with time. At several pH values, the product accumulation did not continue to increase linearly at all times. This indicated that the reaction was not proceeding anymore at the same rate.
The data indicate that the greatest increase in weight was obtained in the dialysis bag that contained the highest concentration gradient for sucrose (bag 3), with a corresponding lesser weight increase for bag 4 since this experiment contained a concentration gradient half of that of the bag 1 experiment. Inversely, a weight loss was observed in the bag filled with distilled water and placed in a sucrose environment ( bag 2) since in this case, the concentration gradient was reversed.
The fact that the enzyme reaction proceed the fastest at pH 7.0 suggests that the decrease in linearity was due to the quick conversion of substrate into product and so that after 1 minute, the enzyme was running short on substrate. At pH 8.0, we believe that the enzyme became quickly denatured and ceased to work, thus ending the accumulation of product, and hence ceased a change in absorbance.
Since the movement of water cannot be seen directly, the relative changes in weights of dialysis tubes over time were used as indicators for the directional move of water in this experiment. In these experiments we hypothesized that any changes in weights will be a direct consequence of water movement from an area of high water concentration to one with a lower water concentration
End of paper writing aspect
Below are 4sets of data in tables. Only one belongs to the paper that you are re-constructing. It is your job to read attentively, use your biology knowledge and find the correct data set.
AbsorbanceAbsorbanceAbsorbanceAbsorbanceAbsorbance
TimepH 4pH 5pH 6pH 7pH 8
00.0150.055-0.0120.023-0.016
150.0190.061-0.0030.036-0.012
300.0240.0660.0050.044-0.009
450.0270.070.0130.056-0.008
600.030.0760.0210.068-0.008
750.0350.080.0280.078-0.008
900.0380.0850.0340.085-0.008
1050.0420.0890.0420.091-0.008
1200.0450.0940.0480.094-0.008
AbsorbanceAbsorbanceAbsorbanceAbsorbanceAbsorbance
TimepH 4pH 5pH 6pH 7pH 8
0-0.0160.023-0.0120.0550.015
15-0.0120.036-0.0030.0610.019
30-0.0090.0440.0050.0660.024
45-0.0080.0560.0130.070.027
60-0.0080.0680.0210.0760.03
75-0.0080.0780.0280.080.035
90-0.0080.0850.0340.0850.038
105-0.0080.0910.0420.0890.042
120-0.0080.0940.0480.0940.045
For the two tables above, times are in seconds since the start of the experiment.Data are the absorbance recorded at each time point.
Since they all start from a different starting absorbance, they can only be compared if at each pH value, the first data point has zero (0.000) absorbance.
Hence, adjust all data points in each column accordingly. For example, in the first Table, the Absorbance column at pH 4 starts at 0.015. We will make the first data at time 0 equal to 0.000 Absorbance (by subtracting 0.015). But you will have to do that same math for all other data in that specific column, and subtract 0.015. Do the same for each column, by making the first data point equal to 0.000, and adjusting the other data accordingly. This is called normalization.
Note : you can paste the data it into your Excel sheet and do the calculations there ! Once data are normalized, use them to make your graph in Excel.
When finished, grab the correct two tables and paste them in your lab report word file.
In the two tables below, the recorded times are actual day times ( am or pm), and the recorded weights of bags in grams.
Once again, recordings were done at different times of day and they can only be compared easily if we start a similar starting point for each experiment.
Convert times to relative times by referring each first time point in each time column as time zero (0) and adjusting all other time points accordingly. They thus become time passed since time zero ( thus 10:35 am in the first column becomes 0, and 10:45 becomes 10 min, 10:55 becomes 20 min, …and so on)
The bags also have different starting weights and comparison becomes much easier if they are adjusted so we can refer to all weights as weight changes since time zero.
Thus, the first measured weight in each bag column becomes zero, and all others become adjusted as the change in weight of that specific bag since time zero. Thus Bag 1 in the first table will get a value of 0 grams at the start (10:35 am, being time point zero) by subtracting 9.9. All other values of that specific column of Bag1 will then also need to have 9.9 subtracted. Thus, 10 minutes later ( at 10:45 am), the weight is the bag will be -0.1 grams ( the bag thus lost 0.1 grams in weight compared to the start). Do similar calculations for all columns in that table.
TimeBag 1TimeBag 2TimeBag 3Time Bag 4
10:35 am9.9 gr10:38am10.6 gr10:40am9.5 gr10:37am10.1 gr
10:45am9.8 gr10:48am10.0 gr10:50am10.1 gr10:47am10.4 gr
10:55am10.0 gr10:58am9.60 gr11:00am10.5 gr10:57am10.8 gr
11:05am10.0 gr11:08am9.00 gr11:10am11.2 gr11:07am11.0 gr
TimeBag 1TimeBag 2TimeBag 3Time Bag 4
2:50 pm10.2 gr2:52 pm9.0 gr2:55 pm9.9 gr2:58 pm11.6 gr
3:00 pm10.1gr3:02 pm9.6 gr3:05 pm10.2 gr3:08 pm11.1 gr
3:10 pm10.3 gr3:12 pm10.0 gr3:15 pm10.6 gr3:18 pm10.5 gr
3:20 pm10.3 gr3:22 pm10.7 gr3:25 pm10.8 gr3:28 pm9.80 gr
Final note: The graphs you make will have multiple lines in it. Watch the following video to see how this is done. One you complete a graph, it can be copied and pated into your word file.