Biology Core Practicals :2 - Investigate The Effect Of pH On Enzyme Activity Flashcards
Name a common enzyme
Amylase
Where is amylase made in a human?
Secretes from the saliva gland
Secretes from the pancreas
What does amylase do?
It catalyses the break down of starch into smaller molecules
What is the first step in this practical?
Drop one drop of iodine solution into each depression of the dimple spotting dial
Second Step: How much amylase solution do you measure?
2cm3 (cm cubed) using a syringe
Where do you deposit the 2cm3 amylase solution?
Into a test tube
What do you add to the test tube after adding the amylase solution?
1cm3 (cm cubed) of your pH solution, using a syringe
What should you record?
The pH of the solution you are using
After adding the amylase & pH solution, what else do you add?
2cm3 (cm cubed) of starch solution
After amylase, pH & starch solutions are added to the test tube, what do you do next?
Start the stopwatch and wait for 20 seconds
After 20 seconds what do you do?
Take a sample of the solution using you pipette and deposit one drop into the first ‘iodine filled dimple’
What does it indicate if the iodine turns black?
There is still starch in the mixture
If there is still starch in the mixture, how long should you wait until testing again?
10 seconds
How long should you leave in between adding each drop of mixture into the ‘iodine filled dimple’?
10 second intervals
What must you note and observe?
Iodine colour changes, noting the times of these changes
What does the colour change indicate?
That starch has been broken down by the amylase and is no longer present
When repeating the experiment, what must you change?
The different pH of solutions you are using
How many different pH solutions must you do? Minimum
4 different pH solutions
Why do you do 4 different pH solutions?
To have a range of data to anyalise
Why must you repeat the experiment?
To obtain a more accurate value at mean pH
In the presence of starch, what colour does iodine turn?
From yellow/brown to blue/black colour
