RP 1 - Investigation into the effect of temperature on the rate of the reaction catalysed by trypsin

Question 1

What are the factors that affect enzyme activity (4)?

Answer 1

Enzyme concentration
Substrate concentration
Temperature
pH

Question 2

Suggest a suitable control for this practical, measuring enzyme activiry

Answer 2

Replace the enzyme solution with distilled water or boiled enzyme solution

Question 3

How can the results of the practical measuring enzyme activity be used to find the initial rate of reaction?

Answer 3

Plot results on a graph of ‘rate of reaction’ against ‘time’
Draw a tangent at time=0 to find the initial rate

Question 4

How is the rate of reaction calculated from time?

Answer 4

Rate of reaction =1/time

Question 5

You used a buffer in your investigation. Explain why buffers are used.

Answer 5

To maintain the same pH throughout the whole investigation

Question 6

You left the test tubes in the water bath for 10 mins before you added the enzyme to the milk powder solutions. Explain why you did this

Answer 6

so the milk powder solutions in each test tube are at the same desired temperature during the reaction

Question 7

Describe and explain what you did to make sure the temperatures of the water baths were as reliable as possible (2)

Answer 7

Used a thermometer to monitor the temperature of the water bath
make sure it stays constant by adding more hot water if needed

Question 8

Explain why you set up three experiments at each temperature

Answer 8

so a mean result can be calculated - more reliable
identify anomalies

Question 9

It is difficult to decide when the solution of milk powder goes clear. Suggest one better way of determining when the solution of milk powder goes clear.

Answer 9

Use a colorimeter to measure how much light can be transmitted through/absorbed

Question 10

In this experiment, you controlled the temperature of the water bath. List two other variables you controlled in this experiment

Answer 10

Volume of trypsin added
Volume of milk powder solution

Question 11

Describe how you could change the method to make it more reliable

Answer 11

Repeat the experiment and do it with more temperatures