BIOLOGY PRACTICAL QUESTION WITH ANSWERS PHOTOSYTHESIS
The purpose of this practical is to prove that chlorophyll is required for photosynthesis.
This is done by using iodine to test a variegated leaf for starch. The parts of the leaf containing chlorophyll are expected to contain starch, while the parts lacking chlorophyll are expected to lack starch.
This section contains the following:
_ Procedure
_ Materials
_ Sample photosynthesis practical with solutions
Procedure
1. Use iodine tincture from the pharmacy without dilution.
2. Prepare hot water bathes. The water should be boiling.
3. While the water gets hot, send the students to gather small leaves. The best have no waxy coating and are varigated (have sections without green).
4. The leaves should be boiled in the hot water bath for one minute.
5. Each group should then move its leaf into their test tube and cover it with methylated spirit.
6. Each group should then heat their test tube in a water bath. Over time, the leaf should decolorize and the methylated spirit will turn bight green.
The chlorophyll has been extracted and moved to the spirit. A well chosen leaf should turn completely white, although this does not always happen.
7. After decolorization, dips the leaves briefly in the hot water.
8. For leaves that turn white, students should test them for starch with drops of iodine solution.
BIOLOGY PRACTICAL QUESTION WITH ANSWERS PHOTOSYTHESIS