i) Take a de-starch potted plant.
ii) Put some potassium hydroxide in flask and put a cork on its mouth.
iii) Place the plant in light for photosynthesis.
iv) Select a leaf of plant but do not pluck it.
v) Place half of this leaf inside the flask.
vi) Put the pot of plant in light for 5-6 hours.
vii) Detach the leaf and test it for starch.
viii) Part of leaf outside flask turned blue while part of inside remain brown.
ix) KOH present inside flask stored all of the Carbon dioxide and due to
absence of carbon dioxide no photosynthesis takes place.