Demonstrating Digestion & Absorption
This lab will be assessed on Conclusion & Evaluation.
Introduction
The human digestive tract prepares food for use by the body’s cells through 5 basic activities:ingestion, peristalsis, digestion, absorption and elimination. In this investigation you will observe the
effects of digestion on the ability to absorb carbohydrates.
Aim
To demonstrate the processes of digestion and absorption in humans.
Materials
Dialysis tubing 20cm3 long x 4
Beaker 250cm3 x 5
Distilled water
Amylase solution 1%
Starch solution 1%
Glucose solution 1%
Sticky labels
Stop clock
Measuring cylinder 100cm3
Pipettes x 4
Iodine solution
Benedict’s solution
Bunsen burner
Tripod
Gauze
Test tube x 8
Test tube holder (tongs)
Test tube rack
Goggles
Water bath set to 40°C
Diagram
Amylase
A
Starch
B
Dialysis tubing
Glucose
C
50% Amylase + 50%
starch solution
D
Distilled water
Procedure
1. Take 4 pieces of dialysis tubing and tie a knot in the end of each. You may need to wet the
tubing first.
2. Using a pipette measure an equal volume of solution and pour into the relevant tubing.
A
amylase solution
B
starch solution
C
glucose solution
D
half amylase and half starch solution
3. Carefully secure the unsealed end of the dialysis tubing using string.
4. Place each bag into a different beaker and label it accordingly.
5. Pour an equal volume of distilled water over the dialysis bags in each beaker.
6. Leave the set up on the side.
7. Remove the dialysis bags and pour the contents into 2 test tubes. You should now have 8
tubes.
8. Test the contents of one set of 4 for the presence of starch, using iodine.
9. Test the contents of the other set of 4 for the presence of sugar using Benedict’s solution.
Remember to heat.
10. Test the contents of the distilled water in the 4 beakers for the presence of starch and sugar.
Results
Record any qualitative observations. Present your findings in an appropriate manner.
Task

Conclusion and Evaluation (CE)


State a conclusion, with justification, based on a reasonable interpretation of the data
obtained.
Evaluate weaknesses and limitations in the procedure.
Suggest realistic improvements in respect of identified weaknesses and limitations.
c=2
p=1
n=0
Concluding
Evaluating procedure(s)
States a conclusion, with
justification, based on a
reasonable interpretation of
the data.
States a conclusion based
on a reasonable
interpretation of the data.
Evaluates weaknesses and
limitations.
States no conclusion or the
conclusion is based on an
unreasonable interpretation
of the data.
Identifies some weaknesses
and limitations, but the
evaluation is weak or
missing.
Identifies irrelevant
weaknesses and limitations.
Improving the
investigation
Suggests realistic
improvements in respect of
identified weaknesses and
limitations.
Suggests only superficial
improvements.
Suggests unrealistic
improvements.