To investigate the effect of temperature on the rate of enzyme activity

        PROCEDURE

1. Add yeast, water and pH 9 buffer to the cylinder.
2. Add hydrogen peroxide to a boiling tube.
3. Stand the cylinder and boiling tube in an ice-cold water bath until the desired temperature (0⁰C) is reached.
4. Add the hydrogen peroxide into the cylinder.
5. Note the volume in the cylinder immediately and record.
6. Read the volume again after 2 minutes and record.
7. Calculate the height of foam (activity of enzyme).
8. Repeat the procedure for other temperatures.
9. Record results

2007 Q7

2007

Q7

(a) i – An enzyme is a biological catalyst

ii – A structural protein is keratin

(b) i – enzyme used – catalase

ii – substrate used – Hydrogen Peroxide

iii – the pH was kept costant throught the experiment

iv – pH was kept constant using pH buffer (pH buffer 10)

v – temperature was varied by placing the cylinders in water baths of different temperatures and checking the temperature of each using a thermometer.

vi – the enzyme was added to the substrate

the stopwatch was started

the height of foam produced was measured at set time intervals

amount of foam produced in a set time indicated rate of activity

vii – Result – lower temperatures allowed less foam to form

- more foam was produced at temperatures closer to 37 degrees

- Less activity occured at higher temperatures due to denaturation of the enzyme

- therefore enzyme activity varies with temperature and as catalase is a biological vvvvvvvvvvvv

  catalyst, its optimum temperature is about 37 degrees.