Investigating Photosynthesis
Demonstrating the conditions
needed for photosynthesis
to occur.
Normal,
in a light window
In the dark
Without chlorophyll
Without
carbon dioxide
Leave
Normal, in a light
window
plants
Without chlorophyll
in these
conditions
for a few
days.
In the dark
Without
carbon dioxide
Now test for starch in the leaves.
If there is starch in the leaf,
then photosynthesis must have happened.
If there is no starch in the leaf,
then there was no photosynthesis
Testing Leaves for Starch
Place leaf in
alcohol
Testing Leaves for Starch
Leave in
hot water
for 3 mins
Testing Leaves for Starch
Rinse in
the
hot water
Testing Leaves for Starch
Add 1 drop of iodine
Rinse in
the
hot water
Lay on a white tile
Testing Leaves for Starch
5
Add 1 drop of iodine
1
Place leaf in
alcohol
2
Leave in
hot water
for 3
minutes
3
Rinse in
the
hot water
4
Lay on a
white tile
Results of the Starch Test
No
Chlorophyll
Normal
No light
No CO2
Starch present
No starch
No starch
No starch in
the yellow bits
Photosynthesis
occurred
No
photosynthesis
without light
No
photosynthesis
without carbon
dioxide
No
photosynthesis
without
chlorophyll
Conclusions
For photosynthesis you must have:
carbon dioxide
water
chlorophyll
light