ATS GCSE BIOLOGY - RP5 Effect of pH on Amylase Key words

• amylase alternative aim

  investigate the effect of temperature on amylase by placing starch and amylase at different temperatures

  
• amylase rate of reaction

  1/time (s)units = per second s-1this can be plotted on the y axis instead of time (s)

  
• amylase graph

  Time taken to break down starch (s) - on the y-axispH of solution - on the x-axis

  
• amylase results table

  pH of solutiontime taken for amylase to completely break down the starch in seconds (s)

  
• amylase method

  1. place one drop of iodine solution into each depression on the spotting tile2. place labelled test tubes containing the buffered pH solutions, amylase solution and starch solutions in to the water bath3. allow the solutions to reach 25 °C4. add 2cm3 of one of the buffered solutions to a test tube.5. use the syringe to place 2 cm3 of amylase into the buffered pH solution.6. use another syringe to add 2 cm3 of starch to the amylase/buffer solution.7. immediately start the stop clock and leave it on throughout the test. 8. mix using a glass rod.9. after 30 seconds, remove one drop of the mixture with a glass rodplace this drop on the first depression of the spotting tile with the iodine solution10. rinse the rod. 11. use the glass rod to remove one drop of the mixture every 30 seconds Put each drop onto the iodine solution in the next depression on the spotting tile. Rinse the glass rod with water after each drop. Continue until the iodine solution and the amylase/buffer/starch mixture remain orange.12. repeat the procedure with solutions of other pHs13. record results in a table

  
• amylase equipment

  1. test tubes2. a test tube rack3. water bath (electrical or Bunsen burner and beakers)4. spotting tiles5. 5cm3 measuring cylinder6. syringes7. a stop clock 8. starch solution9. amylase solution10. buffered solutions covering a range of pH, each with a labelled syringe/ plastic pipette11. iodine solution 12. syringes

  
• hazcards


  cards with information about using and disposing chemicals safely

  
• amylase risk assessment

  1. safety goggles should be worn in the presence of hot water in water baths2. safety goggles should be worn throughout3. take care with boiling water.4. all solutions, once made up, are low hazard (refer to Hazcard 33 for amylase)5. iodine solution may irritate the eyes so safety goggles should be worn (refer to Hazcards 54A and 54B)6. universal buffer solution is an irritant(refer to Hazcards 9, 14, 72, and 91)7. care should be taken with the use of naked flames in this experiment if you are using Bunsen burners to make water baths8. care should be taken with the presence of water and electrical equipment, if electrical water baths are being used9. some people are allergic to enzymes avoid contact with skin10. no eating or drinking in the laboratory
• amylase control variables

  volume of pH buffervolume of amylase solutionconcentration of amylase solutionvolume of starch solutionconcentration of starch solutiontemperature

  
• amylase dependent variable


  time taken for amylase to completely break down the starch in seconds (s)

  
• amylase independent variable


  pH of solution

  
• temperature

  must be controlled by use of a water bath or electric heatercontrol variable

  
• iodine solution


  is to be used to test for starch every 30 seconds

  
• continuous sampling technique


  used to determine the time taken to completely digest a starch solution at a range of pH values

  
• amylase aim

  investigate the effect of pH on the rate of reaction of amylase enzyme

  
• preliminary experiment


  it is best to check that the amylase breaks down the starch at an appropriate rateat around the optimum pH of 6 the end point should be reached within 1‒2 minutes