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Biology Laboratory Report

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F.3 Biology Laboratory Report Investigating the Effect of Temperature and pH on the Rate of Enzyme Activity Date: 20 February, 2009 Team members: Christy Choi (5), Kristy Chong (6), Chloe Chow (7), Jaime Chung (8) Purpose: To investigate the effect of temperature and pH on the rate of enzyme activity Materials and Apparatus: 2 spotting tiles, droppers, 2 beakers, water bath, warm water, ice water, amylase solution, starch solution, iodine solution, hydrochloric acid, sodium hydroxide Method: We can investigate by carry out a test. The rate of reaction can be measured by how quickly starch molecules, which act as the substrates, to disappear. Iodine test will be carried out to show the disappearance of starch. The starch solution will turn blue-black colour when starch is present. Prepare starch solution and amylase solution in different conditions. Then we have to mix the two solutions and return it back in the same conditions. For every specific time intervals, we have to transfer different mixtures to separate spotting tiles containing iodine drops. ...read more.


Record the time as zero immediately. 5. For every 1 minute, transfer a drop of each of the mixture to an iodine drop on the spot plates (6 separate spot plates for the 6 mixtures) 6. Repeat this cycle for each mixture until the blue-black colour disappears. Record the time for the blue-black colour to disappear for each mixture. Conditions Time for the starch to disappear (min) Ice bath (0 degree Celsius) 11 Boiling water bath (100 degree Celsius) No change Hydrochloric acid No change Sodium hydroxide No change Room temperature 4.5 With double amount of amylase solution 2 Results: Discussions: It takes 11 minutes for the starch in the mixture left in the ice bath to be broken down and 4.5 minutes for that left in tap water. From this we can see that enzymes work better at higher temperature. The kinetic energy of amylases is very low at around 0 degree Celsius. They become inactive and the reaction rate is very low. ...read more.


In order to ensure that the test is fair, we mixed the amylase solution and the starch solution of each mixture for the 6 beakers at the same time. Apart from this, we add a drop of the 6 mixtures on the spot plates at the same time for each minute. This is to ensure that the time for the disappearance of the blue-black colour is only due to the temperature of the mixture (enzymes) and is irrelevant to the period of time. However, the result for the mixture in ice bath may not be as accurate since the temperature of the mixture may increase during the test due to the melting of ice. So, the time taken is a bit different from our expected result. The time taken should be longer. Conclusion: Amylase works better at room temperature than at 0 degree Celsius, i.e. the rate of the enzymatic reaction is low at low temperature. More amount of amylase can further increase the rate of enzymatic reaction. However, Enzymes do not work at high temperature and extreme pH values as they are denatured under these conditions. ...read more.

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