4.1 effect of substrate conc

Question 1

How do we investigate the effect of substate concentration on enzyme activity

Answer 1

1. label 100cm3 beakers with 20,16,8,4 & 2
2. put 30cm of 20 vol hydrogen peroxide
3. add 16v of this and 4cm of distilled water
4. now create the rest of the dilutions by adding 10v from the previous beaker and 10cm of distilled water to get 8,4 and 2
5. set up the apparatus: Conical flask with a delivery tube attached to a measuring cylinder in a water through
6. Put 10cm3 20 vol. hydrogen peroxide into conical flask
7. Record the starting position of the water in the measuring cylinder in a table.
8. Place 20cm cylinder of potato puree into conical flask and quickly secure the bung and start the stopwatch
9. Record the volume of gas given off every 30 seconds for 3 minutes.
10. Repeat for other concentrations with a rinsed flask and a full measuring cylinder
11. Exchange data with others to get three values for each concentration for a mean.
12. calculate standard deviation and rate

Question 2

What is the reaction that is happening when potato puree is added to hydrogen peroxide

Answer 2

The enzyme catalase in the potato catalyses hydrogen peroxide to oxygen and water

Question 3

How is rate of reaction measured using hydrogen peroxide and catalase

Answer 3

volume of gas produced/a given time

Question 4

What are control variables for the hydrogen peroxide practical

Answer 4

Enzyme volume and concentration temperature

Question 5

What are the safety precautions involved in hydrogen peroxide

Answer 5

Hydrogen peroxide is an irritant where eye protection and avoid contact with skin

Question 6

How does the shape of the rate graph Makes sense using biological ideas and relevant enzyme theory

Answer 6

The rate is highest initially where most enzyme substrate complexes form therefore most oxygen is produced then rate decreases as less enzymes are available And the graph plateaus when it has reached saturation point where all enzymes are occupied

Question 7

Why is it important to keep the volume of potato puree the same

Answer 7

To ensure the volume of catalase was the same for all concentrations of hydrogen peroxide

Question 8

What are the limitations of this Experiment and how do we overcome them

Answer 8

There was no step that controlled the temperature, We have to use a water bath to keep it constant