Activity 1.1 Class 7 Science

Nutrition in Plants 

 Activity 1.1 Class 7 Science

Aim of activity

To find the presence of starch in plants kept in light.

Material used in the activity

1. Two potted plants

2. Iodine

3. Alcohol

4. Water bath

5. Burner

6. Watch glass or Dish

Procedure

We will take two potted plants of the same kind example and keep one plant in the dark and the other in sunlight for 72 hours.

After 72 hours we will pluck leaves from both plants and keep them separately.

 

Now we will perform an iodine test. We take plucked leaves and boil the leaves for 10 minutes in water, and then boil the leaves in alcohol.

The beaker containing alcohol should be placed in a water bath.

This process makes the leaves completely free of chlorophyll. Now we will wash the leaves.

Now place the leaves in iodine solution for a few minutes.

Now leave the pot which was earlier kept in the dark, in

the sunlight for 3 – 4 days.

Observation

After performing the iodine test, we see the leaf kept in the sunlight turns blue and black but the leaf kept in the dark does not change in colour.

Now, we will perform an iodine test again for the plant that we kept in sunlight (earlier that was kept in the dark). The leaves turn blue-black.

Explanation

When iodine is added to starch-containing items, it forms a complex blue-black substance.

This is a simple activity to test the presence of starch in green plants.

Conclusion

This activity shows that plants (mostly green plants) contain chlorophyll and perform photosynthesis in the presence of sunlight.

Starch is formed in this process.

 we can easily find the presence of starch in leaves through iodine test.