Practical 1

Question 1

Name the factors that can affect the rate of an enzyme controlled reaction

Answer 1

Enzyme concentration, substrate concentration, pH, temperature and inhibitors

Question 2

How is a control set up in a practical measuring enzyme activity?

Answer 2

Replace enzyme solution with distilled water

Question 3

Outline the practical procedure used to measure the effect of temperature on enzyme activity, using trypsin + milk

Answer 3

-Immerse equal volumes of trypsin + milk (in different test tubes) in a water bath for 5 mins to get to same temp
-Mix together + immediately start timing, record time taken for milk to be hydrolysed ( colourless)
-Test at least 5 temps, with 3 repeats for each

Question 4

How is rate of reaction calculated from time?

Answer 4

Rate of reaction = 1/time

Question 5

What is the effect of temperature on enzyme activity?

Answer 5

-As temp increases, kinetic energy increases so more ES complexes form + the ROR increases up to optimum temp
-Beyond that, bonds in enzyme tertiary structure break, changing shape of active site. Substrate + enzyme no longer complementary so ROR decreases.

Question 6

Method limitations

Answer 6

• End point was subjective which leads to inaccurate ‘time taken’ measurements