Enzymes - Questions.2 HKALE 1995 Biology Paper I 2 HKALE...

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Questions................................................................................................................2HKALE 1995 Biology Paper I...............................................................................2HKALE 1996 Biology Paper I...............................................................................3HKALE 1997 Biology Paper I...............................................................................5HKALE 1998 Biology Paper I...............................................................................6HKALE 1999 Biology Paper I B2.........................................................................6HKALE 1995 Biology Paper I...............................................................................9Temperature /°C............................................................................................................10HKALE 1996 Biology Paper I.............................................................................11HKALE 1997 Biology Paper I.............................................................................13HKALE 1998 Biology Paper I.............................................................................13
QuestionsQuestionsHKALE 1995 Biology Paper IHKALE 1995 Biology Paper I8.(a)An experiment was conducted to investigate the effect of temperature on the activities of amylases Iand II. These enzymes were obtained from the same type of tissue of vertebrate animals Iand IIrespectively. Similar pH, enzyme concentration and substrate concentration were used. The experimental data obtained are recorded in the following table :Temperature/Time for complete digestion of 1 unit of substrate / minuteAmylase IAmylase 102.05.0151.63.5201.52.5251.62.0302.01.6354.01.44010.01.5(i)Plot a graph to demonstrate the effect of temperature on the activities of amylases Iand II.(5 marks)(ii)Explain the results for amylase I.(2 marks)(iii)What are the optimum temperatures for amylase Iand amylase II? What thermoregulatory ability would the data for amylase Isuggest for vertebrate animal I?(2 marks)(b)The graph below shows the effects of two chemicals, A and B, on the activity of amylase I. Similar pH, temperature, enzyme concentration and chemical concentration were used in the experiment.II
Substrate concentration (arbitrary unit)Amylase IAmylase I+Chemical AAmylase I+Chemical BEnzyme activity (arbitrary unit)(i)Compare and contrast the effects of chemical A and chemical B on the activity of amylase I(3 marks)(ii)Explain how each chemical, A and B, exerts its effect on amylase I. (3 marks).(Total : 15 marks)Suggested Solution…HKALE 1996 Biology Paper IHKALE 1996 Biology Paper I10.(a)A student performed an experiment to monitor the progress of a simple enzyme-catalysed reaction involving one substrate and one product. He prepared replicate reaction tubes. In each tube, the concentration of only one reaction component, either the substrate or product, was measured. The results of three selected tubes are shown as curves A, B and C below :
(i)Identify which measured component, substrate or product, is represented by each curve.(1marks)(ii)It was realized that the reaction mixture in one of the three tubes had been wrongly prepared. This resulted in a different reaction condition.(1)State which curve represents the result of an error in the preparation. Give a reason for your choice. Suggest two possible mistakes in the student's preparation of this reaction mixture.(3marks)

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