photosynthesis1

photosynthesis1 - Transcript

09/17/11
Photosynthesis
光 光 光 光
光光光光光光光光光光光
光光光
09/17/11
Leaf 葉葉
X-section
葉葉葉 :
Palisade
mesophyll
葉葉葉葉
Chloroplast
葉葉葉
Quick Revision :
Where does photosynthesis occur 葉
葉葉葉葉葉葉葉葉葉葉
Chloroplast under electron microscope
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Warm-up Questions
The following microphotograph is a
transverse section of a
A. stem.
B. leaf.
C. root.
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Sorry, you’ve got the wrong answer!!!
Can you find cortex ( 葉葉 ), which is
very obvious in a cross-section of a
stem ?
Try again...
09/17/11
Sorry, you’ve got the wrong answer!!!
Are the vascular bundles( 葉葉葉 )
concentrated in the centre
of the section ?
Try again...
09/17/11
Congratulations!!!
You’ve got the
correct answer!!!
Go to next
question...
09/17/11
Warm-up Questions
Here is a transverse section of a leaf. It is a
leaf of
A. monocotyledonous xerophyte
B. dicotyledonous hydrophyte
C. dicotyledonous mesophyte
09/17/11
Sorry, you’ve got the wrong answer!!!
Xerophyte is a kind of plants
adapted in desert habitat.
Try again...
09/17/11
Sorry, you’ve got the wrong answer!!!
Hydrophyte is a kind of plants
adapted in aquatic habitat.
Try again...
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Congratulations!!!
You’ve got the
correct answer!!!
Bonus …….
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Bonus :
Give two reasons to support
your answer.

???
???
???
09/17/11
Definition of Photosynthesis
Photosynthesis is a process by which
green plants use sunlight trapped by
chlorophyll to produce organic
compounds (carbodyrate) from carbon
dioxide and water, oxygen is released as
by-product.
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Summary of Photosynthesis
Carbon
dioxide
葉葉葉葉
Water
葉
Oxygen
葉
Glucose
葉葉葉
Chlorophyll
葉葉葉
Sunlight
葉葉
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Experiments :
1.To show that starch is produced during
Photosynthesis.
light
6CO2 葉 6H2O C6H12O6 + 6O2 chlorophyll
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Four steps :
1.Boil the leaf in water, why ?
2.Boil the leaf in alcohol, why ?
3.Wash the leaf in warm water, why ?
4.Add iodine solution to the leaf, what
is the expected result ?
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Experiments :
Aim :
To show that light is necessary for Photosynthesis.
Control :
Do we need a Control for this experiment ?
light
6CO2 葉 6H2O C6H12O6 + 6O2 chlorophyll
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Experiments :
Aim :
To show that chlorophyll is necessary for
photosynthesis.
light
6CO2 葉 6H2O C6H12O6 + 6O2 chlorophyll
Control :
Do we need a Control for this
experiment ?Any Assumption ?
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Experiments :
Aim :
To show that carbon dioxide is necessary for
photosynthesis.
light
6CO2 葉 6H2O C6H12O6 + 6O2 chlorophyll
Any Criticism on the set-up ?
(Think about Variables.)
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Is it better ?
light
6CO2 葉 6H2O C6H12O6 + 6O2 chlorophyll
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Experiments :
Aim :
To show that oxygen is produced during
photosynthesis.
light
6CO2 葉 6H2O C6H12O6 + 6O2 chlorophyll
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Logics
In an experiment, think about :
Aim and objective
Control experiment
Dependent variables
Independent variables
Assumptions
Limitations
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Limitations of the summary
equation :葉 葉
1.Photosynthesis is a two phase process,
which cannot be shown in the equation.
2.Source of oxygen cannot be shown.
3.Glucose is not the first product of
photosynthesis.
6CO2 葉 6H2O C6H12O6 + 6O2
light
chlorophyll
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Photosynthesis involves two stages :
Light reaction
• light is necessary
• light split water into hydrogen and oxygen
Dark reaction
• light is not necessary
• hydrogen is used to reduce carbon dioxide to
carbodyrate
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Water
葉
Light
葉葉
Chlorophyll
葉葉葉
Oxygen
葉
Hydrogen 葉
葉葉葉葉
Released from
the plant Dark reaction
Light reaction
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Hydrogen 葉
葉葉葉葉
Carbon
dioxide
葉葉葉葉
Carbohydrate
葉葉葉葉葉
Dark reaction