Download photosynthesis resource

Plant nutrition
Method of nutrition used by plants is:
photosynthesis.
1. Raw materials needed:
•
CO2 and H2O
2. Conditions present:
•
chlorophyll and sunlight~
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Leaf Structure
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To show presence of stomata
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Section of leaf
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Structure of Stomata
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Stomata: open and close
close
open
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Photosynthesis
• Summary equation:
Light, chlorophyll
• CO2 + H2O
C6H12O6 + O2
Products of photosynthesis:
1 sugar (built up to starch for storage)
2 oxygen.
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How to show that plant is photosynthesising
1. Test for presence of starch .
Photosynthesis is the only way a plant can
produce this.
2. How to test for starch?
Use iodine solution.
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To test a leaf for starch
1.
2.
3.
•
Boil leaf in water.
Boil leaf in alcohol to remove chlorophyll
Wash in water .
Why must the leaf be boiled in water?
To allow I2 solution to penetrate cells.
• Why must the leaf be decolorised?
To allow blue black colour to show up.
• Why must the leaf be washed in water?
To soften it.
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To show that chlorophyll is needed
1 Destarch a potted plant with variegated
leaf by:
2 placing the plant in the light for 48 hrs.
3 Remove a leaf & test for starch.
4 Only the green parts of the leaf give a
dark blue (blue- black) colour with I2
solution.
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To show that light is needed
1.
2.
3.
4.
5.
6.
Destarch 2 potted plants.
Leave 1 in the dark (experimental).
Put one in the light (control).
All other conditions must be the same.
Leave the 2 plants for 48 hrs.
Take a leaf from each plant to test for
starch
In which plant will starch be present?
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To show that CO2 is needed for
photosynthesis
1. Destarch 2 potted plants.
2. Place 1 plant in a bell jar with a dish of
soda lime to absorb CO2.
4. Place the other in a bell jar without CO2
(Which plant is the control?)
5. All other conditions should be the same for both
plants.
6. Leave the plants for 48 hrs, then test the leaf for
starch (with I2 solution).
In which plant will starch be present?
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To show that O2 is given off during photosynthesis
1. Place some water plants eg hydrilla under an
inverted filter funnel in a beaker of H2O.
2. Dissolve some NaHCO3 in the H2O ( to provide
CO2 to the plant.
3. Place the apparatus in sunlight for 6 hrs.
4. Set up a control in the same way, but left in the
dark.
5. Gas bubbles will only be released from the plant
placed in sunlight.
6. This gas rekindles a glowing splint.
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What happens to sugar formed in photosynthesis
1
2
3
4
5
Broken down in respiration.
Built up into starch for storage.
Turned into fats for storage & other uses.
Combined with N2 to form proteins.
Moved to other parts of the plant.
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photosynthesis
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To test for presence of starch using I2 solution
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To show that CO2 is needed for photosynthesis
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To show that chlorophyll is needed.
Use variegated leaf.
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To show that O2 is given off
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To show that O2 is given off.
Glowing splint rekindles.
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