Practical: Enzymes & pH Flashcards
All 6 cards in this deck
What are the steps to investigate the effect of pH on amylase activity?
e.g. testing pH 4, pH 7 and pH 10- Mix starch solution, amylase and a buffer of set pH in a tube in a water bath.
- Every 10 s, take a sample and add it to iodine on a spotting tile.
- Record the time taken for the iodine to stay orange-brown; repeat at each pH (4, 7, 10).
What colour is iodine solution when starch is present, and when it is absent?
Blue-black when starch is present; orange-brown when no starch is present.
In an investigation of the effect of pH on amylase activity, what are the independent and dependent variables?
Independent variable: pH. Dependent variable: time taken for the starch to be broken down (or rate of reaction).
Name three variables that must be controlled in an investigation of the effect of pH on amylase activity.
Temperature, volume and concentration of starch solution, and volume and concentration of amylase.
Why are buffer solutions used in the enzyme and pH practical?
To keep the pH of each mixture at a fixed, known value throughout the reaction.
True or false? In the amylase and iodine practical, the end point is when the iodine stays orange-brown.
True. Orange-brown iodine shows all the starch has been broken down.