Amylase practical - Bio

Question 1

how to investigate the effect of pH on enzyme activity

Answer 1

1. Put a drop of iodine into each spotting tile
2. Take 3 test tubes, add 2cm^3 of starch solution, in another, add 2cm^3 of amylase solution, and in the last, add 2cm^3 of H 5 buffer solution
3. place all 3 test tubes in a water bath at 30 degrees and leave them there for 10 minutes
4. Combine the three solutions into one test tube and mix with a stirring rod
5. Return the test tube to the waterbath and set a stopwatch
   6.After 30 seconds, use the stirring rod to transfer one drop of the solution to one of the spotting tiles which contain iodine
6. If starch is present, solution will go blue/black
7. Keep taking samples every 30 seconds until iodine remains brown/orange
8. Repeat the whole experiment again using different pH buffers

Question 2

what is iodine used for

Answer 2

to test for the presence of starch

Question 3

why do we put buffer solution in one of the test tubes

Answer 3

so it can control the pH

Question 4

why do we place the test tubes in a water bath for 10 minutes

Answer 4

to allow the solutions to reach the correct temperature for the enzymes to start working

Question 5

what does it mean when starch stays orange

Answer 5

starch is no longer present, which means the reaction is complete

Question 6

why does taking a sample every 30 seconds cause a problem

Answer 6

we only have an approximate time for the reaction to complete, we could fix this by taking samples every 10 seconds

Question 7

why might the iodine colour change cause problems

Answer 7

because the colour change is not always obvious, it tends to be gradual, so we might have a small amount of blue black mixed with orange
- to fix this, we could ask several people to look at the spotting tile and decide when the reaction is finished