suggest suitable experiments of show the raw materials required and product formed as a result of photosynthesis?
Carbon dioxide + Chlorophyll + light + water → Oxygen + Glucose
Starch test: After adding iodine solution to a leaf if blue-black colour develops, it indicates that starch is present.
The experiment to demonstrate the raw materials required for photosynthesis is:
Moll’s half-leaf experiment
Requirements: A potted plant, Caustic Potash, container, Iodine, split cork, water.
1. De-starch a potted plant by putting it in complete darkness for two days.
2. Fill a container partly with a strong solution of caustic potash and close it with a split cork.
3. Insert about half of the portion of a leaf of the de-starched plant into the bottle through the split cork.
4. Apply grease on the upper portion of split cork and place the whole apparatus in the light.
5. Test the leaf for starch after 10 hours.
1. Starch test on the portion of the leaf present inside the bottle shows negative which indicates that the process of photosynthesis is absent in this region. This portion of leaf gets, light, chlorophyll and water except for Carbon Dioxide because it is absorbed by the Caustic Potash. Thus, it can be concluded that Carbon Dioxide is necessary for this process.
2. The portion of the leaf present between the split of the split cork also shows negative, due to the lack of Carbon Dioxide and light, therefore indicating that both of them are essential requirements.
3. Only the portions of the leaf present outside the bottle show a positive starch test which indicates that photosynthesis has occurred because all the essential requirements, i.e., light, Chlorophyll, water and Carbon Dioxide are readily available to this portion.
To show that chlorophyll is also an important requirement for photosynthesis;Conduct starch test in a variegated leaf. Only green portions of the leaf show positive results for the test.
It is the process of formation of nutrients in plants in the ‘presence of sunlight’ from carbon dioxide and water. It occurs in the presence of ‘chlorophyll’ that is mainly found in leaves.
Hence we can say that here; ‘carbon dioxide’ and ‘water’ are raw materials whereas sunlight and chlorophyll are catalyst. The products formed are oxygen and sugar in this process.
The balance chemical equation can be written as: