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AQA GCSE Biology Practical 5 REVISE RIGHT NOW
reviserightnow.org
Aim:
Investigate the effect of pH on the rate of reaction of amylase
enzyme.
Equipment:
Iodine Solution Starch solution Thermometer
Spotting tile Amylase solution Water bath
Measuring cylinder Different pH1 buffer solutions Pipette
Method:
1. Place a drop of iodine in each well of a spotting tile.
2. Fill a test tube with 3cm3 starch solution, fill another with 3cm3 amylase solution
and the last one with 3cm3 pH1 buffer solution. Take all the measurements using
a measuring cylinder.
3. Warm all 3 test tubes in a water bath so they reach same temperature. Take the
temperature using a thermometer.
4. Mix all three solutions together.
5. Every 30 seconds, put one drop of the solution into a well containing iodine using
a pipette.
6. The iodine solution will turn blue-black at the beginning. Continue putting drops
of the solution into the spotting tile. Eventually the iodine, will turn orange.
7. This means that all the starch has been broken down by the amylase and is no
longer present.
8. Repeat steps 1-7 with buffer solutions with different pHs.
Why?
You must use the same volume of starch and amylase to ensure it is a fair test
You must ensure all 3 test tubes are at the same temperature so it does not
affect the results.
The optimum pH of amylase is 7 – this can be identified by the solution that takes
the shortest time to change colour.
AQA GCSE Biology Practical 5 REVISE RIGHT NOW
reviserightnow.org
Aim:
Investigate the effect of pH on the rate of reaction of amylase
enzyme.
Equipment:
Iodine Solution Starch solution Thermometer
Spotting tile Amylase solution Water bath
Measuring cylinder Different pH1 buffer solutions Pipette
Method:
1. Place a drop of iodine in each well of a spotting tile.
2. Fill a test tube with 3cm3 starch solution, fill another with 3cm3 amylase solution
and the last one with 3cm3 pH1 buffer solution. Take all the measurements using
a measuring cylinder.
3. Warm all 3 test tubes in a water bath so they reach same temperature. Take the
temperature using a thermometer.
4. Mix all three solutions together.
5. Every 30 seconds, put one drop of the solution into a well containing iodine using
a pipette.
6. The iodine solution will turn blue-black at the beginning. Continue putting drops
of the solution into the spotting tile. Eventually the iodine, will turn orange.
7. This means that all the starch has been broken down by the amylase and is no
longer present.
8. Repeat steps 1-7 with buffer solutions with different pHs.
Why?
You must use the same volume of starch and amylase to ensure it is a fair test
You must ensure all 3 test tubes are at the same temperature so it does not
affect the results.
The optimum pH of amylase is 7 – this can be identified by the solution that takes
the shortest time to change colour.
