CB1G Core Practical - pH and enzymes

Question 1

How is pH controlled

Answer 1

By adding buffer solutions with different pH values

Question 2

How is the rate of enzyme activity measured

Answer 2

By testing the enzyme-substrate solution for the presence of starch at fixed intervals, to find the time taken for all the starch to be digested
Rate = 1/time

Question 3

How is the presence of starch tested

Answer 3

Using iodine solution
If starch is present, the solution turns from brown to blue-black

Question 4

How can the reliability of the results be improved

Answer 4

By repeating the practical at each pH at least 3 times and take a mean of the time taken to find the rate

Question 5

How can the accuracy of the estimate of the optimum pH be improved

Answer 5

By repeating the practical at smaller pH intervals around the estimated optimum pH

Question 6

State a source of error in this practical

Answer 6

The time intervals between testing may be too long to accurately find the time taken for all the starch to be broken down

Question 7

State a hazard and safety precaution in this practical

Answer 7

Iodine solution is an irritant. Avoid contact with skin and eyes