Edexcel IGCSE Biology · Spec 2.23
Photosynthesis Practical
Required practical: measuring the rate of photosynthesis in pondweed and how light intensity affects it.
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Photosynthesis Practical
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Spec 2.23
What you need to know
- Measure the rate of photosynthesis
- Describe the pondweed method
- Explain how light intensity affects the rate
Active recall
Quick check
Answer each question before opening the answer.
How can you show a leaf needs light to make starch?
Destarch the plant, cover part of a leaf, leave in light, then test with iodine — the covered part stays orange (no starch).
Why is the leaf boiled in ethanol during the test?
To remove the chlorophyll so the iodine colour change can be seen clearly.
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