Question

Class 7 Chapter - 1 Nutrition in plants.
Describe an activity to prove that light is essential for photosynthesis.

Answer 1

take a potted plant
select a leaf
take a cardboard and cut a shape on it
place that cardboard on the selected leaf
now place it in sunlight
after 6 hours detach the leaf
perform iodine test to that leaf
the portion which turned blue on touching of iodine contain starch and the rest does not

Answer 2

Aim : to prove that sunlight is necessary for photosynthesis.
MATERIALS REQURIED : de starched plant,iodine solution,petri dish,black paper.
PROCEDURE:
1. take a plant with de stached leaves
2.cover one of its leaves with black paper on which a design is cut.Fix the paper on the leaf in such a manner that light doesnot enter the dark part.
3.place the in sun light.
4.after few hours of exposure to bright sun light,test the leaf which is covered by black paper for the presence of starch.
5.it will be observed that only the parts of the leaf,which could get light through the cut out design,turns blue - black showing the presence of starch.
OBSERVATION:the part which is covered with black paper does not turn blue black.
INFERENCE : we can infer that sun light is necessary for photosynthesis..