| Biology demonstration manual |
Lesson: La nutrition des plantes
Rationale: Show presence of starch in leaves by boiling out the chlorophyll and then doing the iodine-starch test.
leaves (Peanut leaves work fairly well. It's easier to extract chlorophyll from younger leaves.)
alcohol (available in pharmacies)
iodine (MIF kit)
Positive controls (ie. bread, patate douce)
Negative controls (ie. wood, chalk)
Preparation a day before class:
1. Put a glass of alcohol in a pan of boiling water.
2. Put leaves, picked on a sunny day, in boiling water for 30 seconds.
3. Then boil leaves in alcohol for about 20 minutes till the leaves are light green.
4. Dry leaves on paper inside of a book.
5. De-chlorophylled leaves are good for a couple of days.
6. Save the green alcohol to show the class the chlorophyll.
7. Demonstrate the iodine-starch test using both positive and negative controls. (See "Test for Starch", p. 30.)
8. Then add a couple drops of iodine to the de-chlorophylled leaf. Wait a minute and the leaf will turn black.
Source: Mackean Class Experiments in Biology, p. 34.