A student investigates the absorption of digested nutrients from the digestive tract into the bloodstream using a Visking tubing model.
Visking tubing is a selectively permeable membrane that allows small molecules to pass through but prevents large molecules from crossing. The water in the measuring cylinder represents blood, and the Visking tubing bag represents the gut.
The student places different active enzyme and substrate combinations into the bag. After 20 minutes, they test the surrounding water for the presence of starch and reducing sugars.
Complete the table below to predict the results (using yes or no) for each combination.
| Solutions in bag | Starch present in water | Reducing sugar present in water |
|---|---|---|
| starch only | no | no |
| starch and active amylase | ||
| starch and maltase | ||
| starch, active amylase, and active maltase |
Explain how and why the volume of the Visking tubing bag would change if it initially contains a concentrated starch solution and is left in a cylinder of pure water.
Describe the chemical test the student should use to detect the presence of reducing sugars in the water.
Explain how the student could use this model to investigate the effect of temperature on the rate of starch digestion by amylase.