1. Plants and Photosynthesis
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Plants and Photosynthesis
W Richards
The Weald School

2. Things needed for photosynthesis
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SUNLIGHT
Gives the plant energy
CHLOROPHYLL
The green stuff where the chemical reactions happen
WATER
Travels up from the roots
CARBON DIOXIDE
Enters the leaf through small holes on the underneath

3. Photosynthesis equations
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Carbon dioxide + _____ glucose + _____
6CO H20 C6H12O O2
Sunlight
Chlorophyll
The GLUCOSE produced by photosynthesis is used by the plant for _______ (through ____________). It is stored in the plant as ___________.
Words – respiration, starch, water, oxygen, energy

4. Photosynthesis happens in the “palisade” cells in the leaf:
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Photosynthesis happens in the “palisade” cells in the leaf:
Source: BBC Bitesize
Palisade cells

5. Close up on a palisade cell:
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Cell wall
Cell membrane
Chloroplasts (containing chlorophyll)
Large vacuole
Nucleus
Cytoplasm

6. Method for starch test:
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1) Cover up part of the leaf using black card
What effect does this have on the plant?
2) Boil the leaf for a few minutes
What does this do to the leaf?
Soak the leaves in alcohol
What effect does this have on the leaf?
4) Dip the leaves in water
What effect does this have?
5) Drop some iodine onto the leaf
What do you see? Draw and explain your results

7. NO LIGHT, NO PHOTOSYNTHESIS, NO STARCH!
Results:
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The parts of the leaf which have been photosynthesising should have turned black.
This shows that the part of the leaf which was covered up has not been photosynthesising, because it had no light.
NO LIGHT, NO PHOTOSYNTHESIS, NO STARCH!

8. Root hair cells
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Plant roots are made of “root hair cells” which have two features that help them to take in water and nutrients:
Root hair cells
Large surface area
Thin cell membrane

9. Using water Plants need water to do the following: Produce glucose
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Plants need water to do the following:
Produce glucose
Enable transport of minerals
Form fruits
Enable growth
Keep the leaves cool

10. Photosynthesis and Respiration
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In earlier work we looked at respiration:
Glucose oxygen water carbon dioxide
Photosynthesis is the reverse of respiration:
Water carbon dioxide glucose oxygen