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A good way to illustrate the effects of Amylase on starch is to use benedict solution. Observe the picture to the right.

Pour glucose and benedict solution into a test tube. Heat the test tube till it starts to boil. You should see a colour change from blue to orange. (Test tube on the far left, test tube 1)

Press the magnify button

on the top corner to see

this video

Pour the starch and benedict solution into a test tube and heat it till boiling point. No change in colour should occur. (Test tube in the centre, test tube 2)

Pour the starch, amylase and benedict solution into a test tube. Leave it for about 2 - 3 minutes, allowing the enzymes to work. Heat the solution till it start to boil. The test tube should change colour. (test tube on the far right, test tube 3)

Click here for a PDF of the practical. This includes step by step instructions and detailed guide of what you will need, Graph paper, 21 follow up questions about the practical, enzymes and carbohydrates

The reason for the colour change in test tube one, is benedict solution changes colour in the presence of a simple sugar.

Benedict solution dose not change colour when exposed to a complex molecule such as starch (test tube 2).

When amylase is mixed with starch, it is broken down into glucose. This reacts with the benedict solution causing a colour change (test tube 3).

Starch, glucose, yeast and amylase activity

In this activity students will be required to observe the reactions between yeast, glucose, starch and amylase.

Glucose is a main component in energy creation, as shown by this equation:

For aerobic respiration the general equation is:

C6H1 2O 6 + 6O2 6CO2 + 6H2O + 36 ATP (38 in prokaryotes)

Glucose oxygen carbon dioxide water energy

For alcohol fermentation (a type of anaerobic respiration) the general equation is:

C6H1 2O 6 2C2H5OH + 2CO2 + 2 ATP

Glucose ethanol carbon dioxide energy

All living organisms, including yeast undergo these processes to get energy. By mixing glucose and yeast students are able to see the products of respiration (CO2).

Observe the video to the right. Notice the bubbles produced by the yeast with glucose.

When students add starch and amylase they can gain an understanding of:

enzyme activity, products and substrates, structure of carbohydrate molecules and their uses within the cell.