NCERT Solutions Class 7 Science Nutrition in Plants ch1

1. How are leaves tested for starch?

Ans: 

Iodine is used to test the starch in leaves by this scientific way: Chlorophyll from leaf should be removed by boiling it in alcohol, then two drops of iodine are added. If the colour changes to blue, then it indicates the presence of starch in the leaves.

2.Explain food synthesis in green plants by a proper brief description:

Ans:

Leaves do have chlorophyll in them. With the presence of sunlight, leaves use carbon dioxide and H2O to make food. The reaction goes like this:

“Carbon dioxide when added with water in presence of sunlight and chlorophyll gives carbohydrate which is nothing but glucose, and oxygen”.

3. How plants play the role of being the primary source of food?

Ans:

The reaction to show how the plants are the primary source of food:

Solar energy to the green plants. And Green plants to the Herbivores. And Herbivores to the Carnivores.  And all three Green plants, herbivores, Carnivores to Decomposers.