PAG 4.3

Question 1

Equipment available

Answer 1

• 1% Starch solution
• 1% Amylase solution
• Iodine

Note: Iodine solution is orange/brown but in the presence of starch it turns blue/black in colour

• Thermometer
• 5 cm3 and 10 cm3 syringes
• 10 cm3 measuring cylinders
• 50 cm3 beakers
• Test tubes
• Dropping pipettes
• pH test strips
• Marker pen
• Spotting tile
• Stopwatch/timer
• Water baths at 40°C, 60°C and 80°C
• Ice
• Tap Water

Question 2

Method

Answer 2

1. Using your knowledge of enzymes and the factors that affect enzyme activity, suggest a hypothesis for this investigation.
2. Next, using all or some of the equipment and solutions provided, design an experiment to investigate the effect of temperature on amylase activity. Ensure you consider the control of variables in your experiment, the reproducibility of your method and the usefulness of replicates.
3. Check your method with your teacher and carry out your practical activity. Record your data appropriately. If you are working in a group, ensure each student has the opportunity to set up, measure and record readings.
4. Process and present your data appropriately.
5. Finally, draw a conclusion based on the results you obtained and relate this to your original hypothesis.

Question 3

1. Evaluate the method you designed to carry out this activity. Could it be improved? What were the limitations of your investigation?

Answer 3

Any reasonable response based on the students practical, for example related to timings, volumes, repeats etc.

Question 4

2. Why was it important to consider all the variables?

Answer 4

In order to maintain validity by keeping confounding variables constant or monitoring them. This means conclusions will relate to the intended independent variable i.e. temperature.

Question 5

3. Explain the shape of the graph you have drawn using biological ideas and relevant enzyme theory.

Answer 5

Graph should show an increase in the rate of reaction with an increase in temperature until the temperature is high enough to denature the protein ( ̴70°C and above depending on the source of the amylase). This is because the collision rate increases with increasing temperature so enzyme-substrate complexes form more frequently. Students could quote data from their table / graph.

Question 6

4. Discuss the success of this activity with the rest of your class. Consider what worked well and what did not for different individuals/groups in the class.

Answer 6

This will be dependent on the experiments designed and the results obtained by the class. Discussions might include comment on how measurements were taken, the frequency of measurements, the detail included in students’ methods etc.

Question 7

notes

Answer 7

Iodine is an irritant; eye protection (goggles) should be worn