MATERIAL REQUIRED
Iodine Solution (Potassium Iodide), Ethanol, Beaker, Green Leaf of Sunny Place, Bunsen burner, Tripod stand with wire gauze.
THEORY
The process of preparation of food(Glucose/Starch) by green plant by using water and carbon dioxide in presence of sunlight absorbed by chlorophyll is called photosynthesis. The leaf is the chief parts of plant which involve in photosynthesis. The prepared glucose during photosynthesis is stored in leaf of green plant in the form of starch for certain time which is detectable in starch test.
During starch test green leaf of sunny place is boiled in alcohol water to remove green pigment( chlorophyll) and treated with potassium iodide solution. If there is starch in leaf it form starch iodine complex which is dark blue in colour.
PROCEDURE
- Take a green leaf growing in sunny place
- Then clean the leaf
- Take a beaker with alcohol solution (about 60%) then boil it for 5 minute for partial removal of chlorophyll i.e; until pale yellow colour.
- Then clean it by cold water
- Finally pour 2/3 drops of iodine in leaf and apply gentle pressure. Then wait for about 5 minutes.
- The watch the colour changes in leaf.
OBSERVATION
Iodine applied portion of leaf is changed into dark blue colour
RESULT
Starch is present in green leaf growing in sunny place.
CONCLUSION
Hence “green leaf contain starch ” is proved.
PRECAUTIONS
- Apparatus should be handle with care.
- Healthy leaf must be taken.
- Leaf should be taken from sunny place.
- Leaf should boiled till decolorization.