1You can measure the rate of an enzyme-controlled reaction. What is one way to measure how fast the product of the reaction is made?
By measuring the amount of oxygen produced when catalase breaks down hydrogen peroxide.
2What do you need to keep constant when measuring the rate of reaction with catalase?
pH
3How do you prepare the boiling tubes for the catalase experiment?
Fill them with the same volume and concentration of hydrogen peroxide and add equal volumes of buffer solution.
4What are the temperatures used in the catalase experiment?
10˚C, 20˚C, 30˚C, and 40˚C
5How is the average rate of reaction calculated in the catalase experiment?
By dividing the volume of oxygen produced by the time taken.
6What enzyme catalyses the breakdown of starch to maltose?
Amylase
7How do you test for the presence of starch in the amylase experiment?
By adding iodine, which turns blue-black in the presence of starch.
8What does it indicate when the iodine solution no longer turns blue-black?
It indicates that the starch has been broken down by amylase.
9What should be done to ensure accurate results in the amylase experiment?
Repeat the experiment three times at each amylase concentration.
10How do you interpret the initial rates of reaction from a graph?
Compare the rates of reaction at the start of the graph.
11What happens to the graph at 37˚C when the substrate has been used up?
The graph has plateaued.
12Why does the graph plateau earlier at 65˚C compared to 37˚C?
The high temperature causes the enzyme to denature, stopping the reaction sooner.
13What does a constant rate of reaction at 25˚C indicate?
It indicates that the volume of product is continuing to increase because not all of the substrate has been used up.
14How do you calculate the initial rate of reaction using a tangent?
By calculating the gradient of the tangent drawn at t=0.
15What is the formula for calculating the gradient of the tangent?
Gradient = change in y axis / change in x axis.