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LR Biology liver enzyme

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LAB REPORT: BIOLOGY Title: Cow liver catalase experiment. Question: - Is there enzyme activity? -How is the rate of the following reaction with a low temperature compared to a normal temperature? 2H2O2 (catalase as an enzyme) --> 2H2O + O2 Materials: 1000ml of distilled water, 50g of Cow liver, 1x Bunsen burner, 1x Thermometer, 1x Syringe (1 ml � 0.1ml), Tap water, 1x Syringe needle, 50ml of water peroxide (10vol), 1x Stopwatch, 1x Erlenmeyer flask, 1x Measuring cylinder (ml � 1 ml), 2x Water bath, 1x Thin rubber tube. Variables: Independent: Time (by stopwatch, � 3s) Dependent: Amount of O2 released Controlled: Concentration of catalase solution (50g blended in 1000ml of distilled water), amount and concentration of Water Peroxide (50ml, 10vol), amount of catalase added (1ml in syringe � 0.1ml), initial temperature of the catalase solution, Temperature � 1�C, data values (by the same observer with equal/indifferent criteria of judging). Not controlled: Amount of tap water added and number of ice cubes. Diagram: Procedure: - A solution of 50g of catalase per 1000ml of water was prepared. ...read more.


Data processing: Graph 1.1: Results from the experiment plotted as Time vs. O2 produced This graph shows how at a low temperature, rate is slow due to the poor energy it provides. If this graph could continue (which wasn't possible due to the maximum measurement of the measuring cylinder (100ml)), it would show how the reaction comes to an end and the line stabilizes horizontally. It is correct to assume that the highest rate at the beginning of the experiment is due to the absence of substrate for the enzyme to work with. This means, that at the very first contact it has with the water peroxide, all enzymes start working at the same time as they are not affected by the concentration of the substrate since there is enough substrate for all the enzymes to react with. But as time passes, there is less substrate to react with and so the rate slows down. The cause of its instability is that at time 140s and 180s the reaction was shaken, so because of the energy given, the reaction fastened again. ...read more.


Conclusion: We found out experimentally that the reaction with the cow liver catalase was faster at a higher temperature, and that there was enzyme activity in both experiments, by watching how O2 was released in the measuring cylinder. Errors: - The flask was shaken only after 140s since the beginning of the experiment. - There might have been some air in the tube generating the oxygen before the experiment started. - The error for the time is quite large. This is due to the period between a person reading (or even re-reading) the values while the other one is recording the data. - Some air might have escaped back to the syringe. - The temperature inside the reaction was not actually measured, but the tap water outside it. - When putting the cylinder upside-down, some air remained in it and so made it difficult to measure well the O2 released. Improvements: - Shake the flask constantly to allow complete mixture of both reactants. - Re-do the experiment until there is no air at all in the measuring cylinder. - Be permanently watching the thermometer until the college tells you to tell him the data. ?? ?? ?? ?? Nicol�s Lamberti 1 ...read more.

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