Rates Of Enzyme Controlled Reactions

Question 1

Investigating the effect of temperature on catalase activity: - method

Answer 1

2. Set up water baths at temperatures of 40°C, 60°C and 80°C. Also, set up an ice bath, try and keep this at a constant temperature. Use a thermometer to check the temperatures.
3. Set up 4 boiling tubes containing the same volume and concentration of hydrogen peroxide solution. Measure the volumes using measuring cylinders or 10cm​3​ syringes.
4. To keep pH constant, add equal volumes of a suitable buffer solution to each boiling tube.
5. Set up the apparatus with a bung attached to an upside-down measuring cylinder in a trough of water by a delivery tube (see diagram).
6. Put each boiling tube in a water bath/ice bath of a different temperature. Allow the apparatus to equilibrate for 5 minutes.
7. Use a 5cm3​ ​ syringe to add the same volume and concentration of catalase to each boiling tube.
8. Quickly put the bung on and start the timer.
9. Measure the amount of oxygen produced every 30 seconds for 3 minutes. Record this in a results table.

Question 2

Investigating the effect of enzyme (amylase) concentration on the rate of reaction:

Answer 2

Put a drop of iodine in potassium iodide solution into each well onto a spotting tile. Label the wells to help read the results.

2. Prepare boiling tubes with different concentrations of amylase using the ​serial dilutions​ method (see: serial dilutions).
3. Add the same concentration and volume of starch to the first boiling tube. At the same time, start the timer.
4. Use a dropping pipette to put a drop of this mixture into one of the wells containing the iodine solution at regular intervals (e.g. at every 10 seconds).
5. Observe the resulting colour.

Repeat at diff concentrations of amylase

Question 3

How to do a series dilution

Answer 3

1. Set up 5 boiling tubes.
2. Starting with a 2.00% catalase solution, add 4cm​3​ to the first boiling tube.
3. Using a syringe, add 2cm​3​ of the solution in the first tube to the next tube. This makes a 1.00% catalase solution.
4. Repeat this process to make 0.50%, 0.25% and 0.13% solutions.

Question 4

Four factors affecting rate of enzyme reaction

Answer 4

• temp
• enzyme concentration
• substrate concentration
• pH

Question 5

How can you measure rate of reaction using hydrogen peroxide + catalase

Answer 5

Measure volume of oxygen produced in a given time

Question 6

Word equation for action of catalase

Answer 6

Hydrogen peroxide -> oxygen + water

Question 7

control variables

Answer 7

enzyme volume

enzyme concentration

substrate volume

substrate concentration

pH