Question

Given below is the figure of an experimental set-up, showing a physiological act of the plants. Study and answer the following questions:

1. What is the objective of this experiment?
2. Name and define the process shown here.
3. Why do we destarch the leaves before performing the experiment?
4. How do we destarch the leaves?
5. What will be the observation when we pour iodine solution over the bleached experimental leaf?
6. Write a well-balanced equation for the above process.

Answer 1

1. To demonstrate the need for sunlight for photosynthesis.
2. Photosynthesis. Photosynthesis is the process by which plants produce glucose using water, carbon dioxide, sunshine, and chlorophyll pigment in their leaves. Photosynthesis produces glucose and oxygen as its end products. Plants use glucose to power their cells, while other species require oxygen for respiration.
3. We remove starch from a plant to facilitate photosynthesis in the presence of sunlight. If starch is already present in the leaves, photosynthesis does not take place.
4. By keeping the leaves in a dark room for 24 to 48 hours, we can destarch them. This is because darkness inhibits photosynthesis and enables the plant to use up any stored starch.
5. If starch is present, the bleached experimental leaf will turn blue-black when iodine solution is applied. The leaf is said to be starch-free if there is no colour change and it stays brown.
6. \[\ce{6CO2 + 6H2O ->[Sunlight][Chlorophyll] C6H12O6 + 6O2}\]