RPA Effect Of pH On Amylase

Question 1

Describe process

Answer 1

• place drop of iodine into each well of a spotting tile
• fill test tubes with 2cm of starch, amylase and pH 5 buffer solution
• place test tubes in water bath at 30C
• leave for 10 mins to reach correct temp
• combine solutions into one tube and mix with stirring rod
• return to water bath and start stopwatch
• after 30secs using rod to transfer one drop of solution to well in spotting tile which contains iodine
• iodine should turn blue black if starch present
• take sample every 30secs until orange
  = starch no longer present
• repeat using different pH buffers

Question 2

Problems with experiment and how to fix them

Answer 2

• only taking samples every 3 secs
  = only approximate time for reaction to complete
  = take samples every 10 secs
• not always obvious when iodine turns blue black
  = as colour change is gradual
  = ask several people to look at spotting tile and decide when reaction completed