Question

How would you test the presence of starch in leaves?

Answer 1

Experiment to test the presence of starch in leaves:

1. Take two healthy green potted plants of the same type.
2. Keep one potted plant in a dark room for one or two days in order to remove all the starch from the leaves.
3. Keep the other plant in sunlight.
4. Now, take one leaf from each potted plant and put a few drops of iodine solution on them.
5. Note down the change in the colour of both the leaves.

• Observation: No blue-black colour will be observed on the leaves of the plant kept in the dark room. This indicates the absence of starch. Blue-black colour will be observed on the leaves of the plant kept in sunlight. This indicates the presence of starch.
• Concept insight: Plants prepare glucose during photosynthesis which gets stored in plants in the form of starch. Iodine turns blue-black when reacted with starch.