Experiment investigating the effects of changing concentration of starch on the digestion of amylase

Plan

• In this experiment I will be using 5 different concentrations of starch
• I will place 2 drops of iodine solution into a dimple tray
• Then I will take 5cm³ of amylase solution and put it into a test tube
• To this I will add 5cm³ of starch solution
• Using a pipette I will immediately add 2-3 of the mixed solution onto the iodine in the dimple tray and start the stop clock
• After every 30 seconds I will stop the stop clock, note down any colour change and start it again
• I will do this for 240 seconds

Safety

To ensure this experiment is done in a safe way, the following points should be considered: -

• Work surfaces should be cleared
• All chemicals and solution should be treated with care and not swallowed
•  Test tubes should be placed in test tube racks
• Safety goggle should be worn

Fair test

Independent variable

- Concentration of starch

Dependant variable

• Time taken for effect

Control variables

• Same amount of amylase and starch solution
• Same amount of mixed iodine an starch solution out on the iodine for each concentration
• Same time measured
• Same time colour change noted (every 30 sec)
• Same temperature
• Same enzyme (amylase) concentration

Prediction

I predict that the higher the concentration of starch the faster it will change colour. This is because if concentration of starch is higher, it contains stronger starch and so the amylase has more starch to convert

Apparatus

• Starch solution
• Amylase
• Iodine solution
• Measuring cylinders
• Test tubes
• Dimple trays

Method

• Place 2 drops of iodine solution into the dimple tray
• Take 5cm³ of amylase solution into a test tube
• To this add 5cm³ of starch solution
• Immediately using a pipette add 2-3 drops onto the iodine solution in the dimple tray and start the stop clock
• Record the results after every 30 seconds and note down any colour change

Diagram

Results

Conclusion

By doing this experiment I have proved my prediction to be correct and that the higher concentration the less time it took for the starch to digest. This is because the starch was stronger and purer and so the amylase was able to act on it straight away easily digest it. The weaker concentration of starch took longer to digest because it was less concentrated and so the amylase took longer to digest it, as the starch wasn’t strong enough

This experiment has helped me learn the way amylase breaks starch down into smaller glucose molecules and what factors can affect this process.

Evaluation

         Overall I think this experiment went well. The results turned out a expected making them quite accurate and reliable, but I think it would have been better if we repeated the whole experiment at least 3 times to account for any anomalous results and to gain a wider set of results.

        I think the method was quite good but the temperature was not kept constant. This could have affected the results. If I repeat this experiment I will put the test tubes in a water bath and monitor the temperature regularly. The water will help keep the temperature the same throughout the experiment making it a fairer test.