About Lesson
Practical Activity: To show that chlorophyll is necessary for photosynthesis
Requirements
- A variegated leaf.
- Boiling tube
- Ethanol or methylated spirit
- Iodine solution
- Water bath
- White tile
- Means of heating
A variegated leaf is one that has some patches that lack chlorophyll. The parts have other colours such as yellow. These parts lack chlorophyll and therefore photosynthesis does not occur in them.
Procedure
- Detach or remove variegated leaf from a plant that has been exposed to light for at least 3 hours.
- Draw a large diagram to show the distribution of the chlorophyll pigment in the leaf.
- Test the leaf for starch.
- Record your observations in form of a diagram.
Expected Results
The green patches turned blue-black showing the presence of starch.
The white patches turned brown showing the absence of starch.
The green patches had cells that contained chlorophyll hence photosynthesis took place.
The white patches had no chlorophyll hence there was no photosynthesis.
Conclusion
Chlorophyll is necessary for photosynthesis.
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