Loane L S Page3

1- To realise this experience : a transparent jar like a jar of jam.
2- No equipment is really necessary but we can wear gloves to protect hands of coal powder.
3- We need 2 green plants that we could find in a garden, some coal powder, water (enough to fill the jar) and sun of course!
4- The experience lasts arround 1 hour ;10 minutes to prepare it and 50 minutes of waiting.
5-The objective of this experience is to prove that plants need sun to do photosynthesis. This is why we need green plants. They contain chlorophyll which give them this green color. The chlorophyll absorbs light photons to convert it into a light energy and this is the start of photosynthesis process.
6-A hand contamination with plants that could be toxic is possible.
7-Wearing gloves for avoid hand contamination with plants or coal powder.
8- How can we prove that green plants need sun to do photosynthesis ?
9 - Experimental protocol
- First, fill the 2 jars entirely with water.
- Place one of the 2 plants in one of the 2 jars and close it.
- Take the second plant, cover her of coal powder, then put her in the second jar and close the jar .
- Verify that the 2 jars are close then turn them over (the lid must be on the floor).
- Wait 1 hour.
10- After one hour, we can see on the jar which contain the first plant (the plant without coal powder) that there are a lot of bubbles on the plant and on the ledge of the jar. While the second jar (plant covered with coal powder), there are no bubble, nothing has changed.
11- On the plant without the coal powder, the sun light penetrates more easily because there is nothing to block the light so the plant can do photosythesis. However, on the second green plant, the coal powder stop the light so the photosynthesis is not possible. That's explain why there are no bubbles on her.
12) In conclusion, this experience prove that plants need sun to do photosynthesis. This was verified by the presence of bubbles or no after one hour.

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