Lesson Title: Testing a Leaf for Starch
Learning Intention:.
Name the solution used to test leaves
for starch and the colour change it
produces.
Activity:
I will be successful if I can :
Safely test a leaf for Starch and
remember the steps
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Photosynthesis recap
animation
• http://www.kscience.co.uk/animations/phot
osynthesis.swf
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Photosynthesis
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• GLUCOSE is produced
during photosynthesis and
stored as STARCH
• If a leaf has starch in it, it
means photosynthesis has
been taking place
• IODINE solution turns
blue/black if starch is present
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Testing a leaf for starch
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Method 1. Boil the leaf in water for 5 min
(to soften the leaf)
2. PUT OUT THE BUNSEN BURNER
3. Use the glass rod to transfer leaf into boiling tube
4. Place boiling tube back into the hot water to boil the leaf in alcohol
(to remove the green colouring)
5. Carefully lift the leaf out with glass rod and place in hot water to wash the leaf
6. Spread the leaf out on a dimple tile.
Animation
7. Test with Iodine solution
1. Boil in water
- (water in beaker)
2. Boil in alcohol
- (Bunsen switched off !! )
3. Rinse alcohol
off leaf
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4. Test leaf with
Iodine solution
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Starch
present
IF the iodine turns
blue/black THEN
the leaf has starch.
Starch
absent
In the presence of light green plants are
able to make starch (food) in their
leaves
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Aim
• To investigate the conditions
required for photosynthesis
What conditions
do you think are
needed for
photosynthesis?
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Condition
missing
Before
After
testing for testing for
starch
starch
Starch
present
(yes/no)
None
(control)
light
Chlorophyll
Carbon
dioxide
dark
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Method 1. Boil the leaf in water for 5 min
(to soften the leaf)
2. PUT OUT THE BUNSEN BURNER
3. Use the glass rod to transfer leaf into boiling tube
4. Place boiling tube back into the hot water to boil the leaf in alcohol
(to remove the green colouring)
5. Carefully lift the leaf out with glass rod and place in hot water to wash the leaf
6. Spread the leaf out on a dimple tile.
Animation
7. Test with Iodine solution
1. Boil in water
- (water in beaker)
2. Boil in alcohol
- (Bunsen switched off !! )
3. Rinse alcohol
off leaf
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4. Test leaf with
Iodine solution
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Condition
missing
None
(control)
light
Chlorophyll
Carbon
dioxide
Before
After
testing for testing for
starch
starch
Blue/black
Starch
present
(yes/no)
yes
Green
Green
white
Some
blue/black,
some brown
some
brown
no
brown
no
Green
dark
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Green
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Conclusion
• I found out that . . . . (refer
back to your aim)
• Carbon dioxide, light and
chlorophyll are needed for
photosynthesis to take place.
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Lesson 2 - Learning
Intentions
• Through practical work, name
the conditions required for
photosynthesis to take place
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POSTER
• Title – ‘Do plants need
chlorophyll / light / carbon
dioxide for photosynthesis’
• Method, including diagrams, of
how you carried out the
experiment
• Results – what colour did the
iodine test produce
• Conclusion, what do plants need
for photosynthesis.
• Word Equation
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